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Shark attact in Natal
INJURY Volume G/Number
3
The British Journal of Accident Surgery
Shark attack
in Natal
J. A. M. White Principaf Surgeon, Department Addihgton H&pita/, Durban
of Hospital Services, Department
Summary
The injuries in 5 cases of shark attack in Natal during 1973-74 are reviewed. Experience in shark attacks in South Africa during this-period is discussed (1965% 73), and the value of protecting heavily utilized beaches in Natal with nets is assessed. The surgical applications of elasmobranch research at the Oceanographic Research Institute (Durban) and at the Headquarters of the Natal Anti-Shark Measures Board (Umhlanga Rocks) are described. Modern trends in the training of surf life-guards, the provision of basic equipment for primary resuscitation of casualties on the beaches, and the policy of general and local care of these patients in Natal are discussed.
INTRODUCTION DURING the period 1965-74 twenty-six cases of shark attack on humans were recorded in the
Shark Attack Files of the Oceanographic Research Institute (Durban) and the Natal AntiShark Measures Board. Five of these cases were recorded in Natal during 1973-74. The Shark Attack File was started by the late Professor David Davies and covered attacks from Mozambique to the Cape. The comprehensive data recorded on shark attacks were part of a research project on local elasmobranchs. In 1973 the file was taken over by the Anti-Shark Measures Board. Data from these sources regarding attacks have been used, together with personal observation in the series of 5 recent attacks in Natal (1973-74); evidence taken from voluntary life-guards, the records of local doctors who have given primary treatment to the victims, hospital records, and statements from the victims. HISTORY From 1940 to 1974 62 cases of shark attack on humans with a mortality of 40 per cent were
of Surgery,
recorded on the Indian Ocean coast of Southern Africa. Baldridge analysed data recorded in 1165 shark attacks throughout the world (Baldridge, 1973). The mortality rate has fallen in the last two decades to about 20 per cent (Gilbert, 1963a). Between 1944 and 1951 20 attacks took place on the beaches in the central city area of Durban. In 1952 the City of Durban began the present system of off-shore anti-shark nets which protect the popular beaches stretching for two miles north from the entrance to Durban Bay to the Umgeni River. The nylon mesh used to protect bathers and ‘ deep-water ’ surfers is suspended from off-shore buoys. Despite a continuing increase in the numbers using these beaches, no further major incidents have been recorded. In 1960 and 1962 a further series of attacks was reported from the 100 miles of beaches along the South Coast of Natal and led to most beaches being protected by nets. Between 1965 and 1973 only 1 major case of shark attack was reported from Natal, but 20 cases were recorded from unprotected areas in Zululand, Mozambique and the Cape. Campbell commented on the decrease of attacks along our coast despite a marked increase in the number of bathers, ‘ deep-water ’ surfers, skin and scuba divers (Campbell, 1968). During the abnormally wet summer (December, 1973-April, 1974) in Natal and Zululand, 5 cases were recorded of which 4 occurred on one unprotected beach 12 miles south of Durban. Two weremajor attacksand 3 were minor incidents. PREVENTIVE MEASURES AGAINST SHARK AlTACK Species of sharks known to be dangerous to man are found in large numbers along the coast of 187
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Southern Africa (Davies, 1960). Attacks have been reported from the cold waters of the Cape (15” C.) to the warm coral lagoons of Mozambique (21’C.). From 1965 to 1973 only 1 case was reported on a protected beach in Natal. Despite a heavier use of these beaches in the same period, 20 cases were reported from unprotected beaches in other sections of the Indian Ocean coast. In the present series (1973-74) 3 occurred on a ‘ protected ’ beach at a time when the net system was considered to be incomplete, and 2 were on ‘ open ’ beaches. Although the numbers involved are small, the remarkable decrease in shark attacks reported from Natal during the last two decades may be related to the rapid spread of efficient net systems throughout the Province. These net systems have replaced the fixed enclosures which were unsightly, liable to storm damage and corrosion, restrictive and potentially dangerous. Protective systems using submarine cables to produce repellent electrical fields have been developed locally but remain experimental. Preliminary work has been done on the use of acoustic techniques as a shark repellent (Davis, 1974). Nets are expensive, difficult to maintain and are not infallible, fatal attacks having been reported. The nets do not form a continuous barrier nor reach the sea bed. Approximately equal numbers of sharks are caught on the seaward and landward sides of the nets. Dangerous sharks therefore penetrate into the bathing areas. In the net systems of Natal, most sharks are trapped during rhe hours of darkness (Davis, 1974). The nets are thought to produce vibration patterns in the water which stimulate the highly sensitive vibration receptors of the sharks. Sharks are known to be attracted by certain vibration patterns in water, e.g. those set up by other sharks, hooked or injured fish. Sharks within the enclosed area turn out to sea and become entangled in the nets, are designed to trap sharks by their pectoral fins and tails. Once entangled they drown as they cannot move and breathe freely. FACTORS FAVOURING SHARK ATTACK Efficiently maintained nets reduced the number of sharks caught in the enclosed area by up to 80 per cent in a decade (Davies and Campbell, 1962). This fall is not matched by a corresponding fall in the numbers of sharks caught by local It is anglers in immediately adjacent areas. possible that sharks learn to avoid netted areas. Certain conditions are thought to predispose to shark attack (Gilbert, 1963a; Baldridge, 1973).
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a. Seasonal variation Numbers and species of sharks in the region are variable. Carcharinidue (Grey Sharks), Blue Pointers and others are attracted to the beach area of Durban during the autumn and winter months by the activities of the land-based whaling station at the entrance to Durban Bay. At other times there are fewer deep-water species in the inshore areas than indigenous Carcharinidae, which are present throughout the year. The Zambezi Shark (Curcharodon leucas) has been blamed for many attacks along the Natal coast, but there are many closely related species of Carcharinidae which are capable of inflicting injuries indistinguishable from those caused by Carcharodon leucas. In Natal swimming and surfing are possible throughout the year, but more people are at risk during the summer holidays (December to February). All cases reported during 1973-74 occurred during this period. b. Time of day/day of week Baldridge (1973) has indicated that the incidence of shark attack is related to the number of people at risk in the area at any one time. All our cases occurred in the afternoon. Three attacks were at dusk. There is a known tendency for our in-shore species to move toward net systems during a possible ‘ feeding surge ’ in the late afternoon, at a time when beaches are becoming deserted (Davis, 1974). c. Geographical and geomorphological features In Southern Africa the beaches of Natal have the highest numbers at risk throughout the year. Between 1965 and 1974 only 2 cases were reported from protected beaches, 1 on an open beach. Three were from a beach where the nets were temporarily suspect. In the same period 20 cases occurred elsewhere. All were from unprotected beaches and lagoons in Zululand, Mozambique and the Cape. All the recent attacks in Natal took place within 200 m. of the shore. One victim was actually sitting in very shallow water, the other 4 were attacked in an in-shore channel over 3 m. deep. Most Natal beaches shelve steeply to an in-shore channel which is separated from the open sea by a variable sandbar upon which the main surf starts to break. To reach the best surfing zone, this channel must be crossed. Even within promcted areas undetected sharks may come very close inshore by following these channels, and some become ‘ beached ’ during determined attacks.
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d.
Shark Attack in Natal
Meteorological
conditions
All the recent cases occurred in clear weather with good surface visability. All the victims were Caucasian; all were attacked from below; 4 were attacked in the late afternoon or at dusk; 3 had light coloured surf boards and it is possible that, as seen from below the surface of the sea by an attacking shark, 4 of the victims presented a clear colour-contrast with their background. e. Hydrographic features In the recent cases in Natal, sea temperatures were over 21” C. (70” F.) at the time of the attack. Attacks in the Cape (1965-1973) were recorded at water temperatures of 15” C. Wounds in major cold water attacks at the Cape suggest that the Cape Blue Pointer (Carcharodon carcharias) was probably responsible for fatalities. This species represents less than 2 per cent of sharks in Natal waters (Davis, 1974). In Southern Africa water temperatures influence the species of shark responsible for attacks more than the actual incidence of attacks in a given area. The warm water throughout the year in Natal encourages bathers as well as Grey Sharks, which were suspect for two recent attacks in Natal. Turbidity of the surf was noted by Davies (Davies and Campbell, 1962) in 80 per cent of their series and during all our recent cases (1973-74), especially in two major attacks. In summer months heavy rainfall in the catchment areas of Natal’s large rivers causes flooding, and large quantities of dirty water discharge into the sea, contaminating many of the adjacent bathing areas. In-shore species of shark are attracted to turbid water and its contained food within protected areas (Davies, 1961). They have poor distant vision but good near vision in dim light. Decreased salinity of the water favours a high resident population of Grey Sharks, of which Zambezi Shark (Carcharodon Zeucas) is well known for its aggressive tendencies. These are found in the estuaries and lagoons along the coast and they have been found more than 100 miles up the Zambezi River from the coast. Decreased salinity is commonly recorded along our beaches during the summer floods, with their high water temperatures, increased turbidity, and maximal beach use. Depth of water at the time of the attack influences the type of injury and the mortality. Commercial shark fishermen at the Cape, and divers, have a different kind of injury from that of bathers and surfers who are attacked from below. This accounts for the heavy predominance of injuries to the lower limb in reported
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series (Baldridge, 1973). Mortality rates in attacks less than 30 m. from the shore are lower because assistance is more readily available to the victim. However in Natal another factor may be that the Cape Blue Pointer (Carcharodon carcharias) and the Tiger Shark (Galeocerdo cuvieri) are rare in these in-shore waters. These are very aggressive species in the Cape and inflict terrible injuries. The smaller Grey Sharks have different jaw and dental characteristics which influence the type of wounds commonly seen in Natal. The heavy male preponderance in reported series (Baldridge, 1973) is because men swim in deeper water, go further out and engage in ‘ deep-water ’ surfing. Four of our present patients were surfers and male. f. Colour
factors
All our recent cases were male Caucasians, who are most at risk, but other races have been attacked on several occasions. These men venture far from the shore during ‘ deep-water ’ surfing, using light coloured surf boards and presenting a high colour contrast on the surface. All were attacked from below and received leg injuries only. All were wearing short bathing trunks of varying colours. In one case the primary attack was made on the surf board and not on the surfer. Sharks have cone-poor retinae and probably do not see colour as we do (Gilbert, 1963b). Nevertheless, they can appreciate colour contrast, reflectivity and differences in light intensity. Experimental evidence suggests that International Orange (survival equipment) is attractive, but red and black are not attractive to sharks (Baldridge, 1973). g. Other factors Vibration patterns attract and repel sharks. One victim was paddling his feet in very shallow water at the time of the attack. The other 4 victims were either swimming on the surface or paddling their boards. All were at or near favourite fishing spots in turbid water which was contaminated by bait, offal or excrement. Significant bleeding followed each attack but the initial injury or bite was not followed by a determined attack or ‘ frenzy ‘. Injuries recorded in the Shark Attack Files (Fig. 1) indicate that there is a very great difference between a determined attack by a shark using a human as a source of food, and the tentative attacks made on 3 of the recent victims. In this group the shark appeared to be attracted to a surfer swimmer, investigated the source of the attraction but rejected him as a source of
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Fig. I.-Fatal outcome of frenzied attack by Cape Blue Pointer. Coarsely serrated wound edges caused by the widely separated teeth of this species which have lateral serrations.
Fig. 2.-Recent cases with penetrating wound of knee joint. The wound edges are sharp. The diameters of the two curving wounds suggested that the shark (possibly Carcharodon /emus) gripped the flexed knee from below.
food. Two of our 5 cases must therefore be classified as ’ aggressive close passes ’ and not definitive bites. Their injuries are compatible with rough contact with the points of sharp teeth during the shark’s initial scrutiny. Despite the profuse bleeding at some distance from the shore, no further attack was made on 4 of our cases or upon their rescuers during transit to the shore. Human blood does not seem to have the same attraction for sharks as whale, fish or shark blood (Baldridge, 1973).
before they were seized by the leg. Both victims recall striking at the shark.
THE
SHARK
ATTACK
One victim was seized by the toes and forefoot in very shallow water. Two were seized from below and sustained definite bites. Two sustained glancing blows and lacerated wounds. The injuries in all the victims formed a single pattern. Two recent victims clearly described the ‘ bump ’ made by the initial contact with the shark as a sharp blow which threw them out of the water
Fig. 3.-Recent case showing loss of tissue from leg possibly caused by Carcharodon leucns. Fine serrations in the skin edge are seen.
SPECIES
OF SHARK
RESPONSIBLE
Direct identification was impossible. In two aggressive close passes the linear wounds could have been made by any species baring its teeth during scrutiny of a victim. In the two major attacks the character and the differing diameter of the upper and lower wounds suggested not only the direction of the attack but the species of shark responsible (Figs. 2 and 3). The finely serrated wound edges in the skin, tibia and knee joint of these cases suggested that the shark responsible was a Grey Shark (Carcharinus Ieucas or related species), because these sharks have very small pointed teeth set close together in a single row with very fine lateral serrations (Fig. 4). These teeth produce a relatively clean-cut wound of skin, fascia, muscle and bone which contrasts sharply with the rough edged wounds inflicted by
Fig. 4.-Teeth of Carchavodon /emus lateral serrations.
showing fine
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Fig. S.-Jaws and teeth of Carcharodon carcharias showing widely separated teeth with lateral serrations.
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damage to a limb, a small boat or a surf board, but the type of wound may vary from a tangential injury (’ close pass ‘) to a definitive bite. Tentative bites of the limbs account for more than 70 per cent of the wounds in the Shark Attack Files. In 70 per cent of surface swimmers the lower limb only was involved. A shark making an aggressive ‘ close pass ’ can be seen to bare the razor-sharp teeth of its upper jaw, which inflict lacerations, incised wounds and loss of tissue. Davies and Campbell (1962) discussed alternative causes of this type of wound by fish in Natal waters (snoek, barracuda or Spanish mackerel). In a recent case a large Saw Fish penetrated the netting system and inflicted a series of three parallel incised wounds on the anterolateral aspect of the thigh of a swimmer in deep water (Davis, 1974). The distance between the three parallel wounds corresponded exactly to the distance between the serrated edge of the bill of a large Saw Fish. Definitive wounds follow a determined attack. The appearance of the wound varies according to the part or parts of the body seized by the shark and the size of the species responsible. Severe lacerations, loss of soft tissue, amputations,
the Cape Blue Pointer, which has larger teeth, set widely apart (Fig. 5). These cause coarsely serrated wound edges (see Fig. 1). Elasmobranch teeth are cartilaginous but radio-opaque. They can be seen in radiographs as dense triangular opacities in the comminuted bones and adjacent soft tissues following severe injury. In the recent cases all radiographs were negative. Small fragments of finely serrated teeth were recovered from the amputated section of the tibia in one of our recent cases, but were too small for accurate identification of the species responsible for the attack (Davis, 1974). Campbell and others (Campbell, Davies and Copley, 1960) described the appearances of the wounds inflicted by the Ragged Tooth Shark (Curcharius taut-us) (Fig. 7). In one case in the Shark Attack File, the recovery of a single tooth from the femur of the victim enabled the species responsible to be identified as a Tiger Shark (Galeocerdo cuvieri)(Figs. 4,5,6 and 7.) LOCAL CHARACTERISTICS OF SHARK ATTACK WOUNDS Davies and Campbell (1962) indicated that a large Grey Shark has tremendous power in its jaws and is perfectly capable of throwing a young adult out of the water. Its jaws can inflict severe
Fig. 6.-Jaws and teeth of Galeocerdo cuvieri showing closely set teeth with characteristic recurving tip.
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Crushing of tissue is minimal. Profuse and continuing haemorrhage is common. Campbell and others (1960) described the only case of a Ragged Tooth Shark attack in Natal. The species is rare in these waters. Its long pointed teeth are set in irregular rows in both the upper and lower jaws (Fig. 7). These inflicted an avulsion type of injury on the pelvis and abdomen with visceral penetration. The long curved teeth have no lateral serrations and therefore do not cut. As might be expected the wounds were markedly irregular. Puncture wounds may be expected from this type of shark. Deep bacterial contamination is likely. Large Cape Blue Pointers (Cuvchavodon carcharius) inflict gross lacerated wounds with coarsely serrated edges caused by their widely spaced triangular teeth with sharp lateral serrations (Fig. 1). The wounds inflicted by the Tiger Shark (Galeocerdo cuvieri) have no special characteristics. The large teeth are closely set, laterally serrated but have a curving tip which incriminates the species if a tooth can be recovered from the victim. Fig. 7.-Jaws and teeth of Carcharias taitrus showing multiple rows of widely separated long backward curving teeth. comminuted fractures, etc., are recorded with muscle, tendon, nerve and vascular injuries. Injuries of the trunk form only 5 per cent of large series (Davis, 1974). Over 70 per cent of wounds are found to be single (Baldridge, 1973), suggesting one attack or bite. In wounds of the limbs a ‘ step-pattern ’ is sometimes seen. The common Grey Sharks of Natal (Curcharodon Zeucas and related species) have extremely sharp pointed teeth with fine lateral serrations set in a single row in the upper and lower jaws which have a different maximum diameter (Fig. 4). The tine lateral serrations impart a cutting edge resembling that of the Gigli saw. Although the wounds inflicted by these species have the gross characteristics of a lacerated wound, the wound edge in skin and bone is finely serrated (Fig. 3). In the more proximal injuries of the leg, thigh and buttock, the tissue is firmly gripped by the upper and lower jaws and marked accordingly (Fig. 2). The cutting action is effected by violent lateral movements of the body and tail, while the head is stabilized by the pectoral fins. A clean-cut edge to the wounds results with minimal damage to tissue which is not immediately adjacent to the line of severance.
BACTERIOLOGICAL CHARACTERISTICS AlTACK
IN SHARK
Davies and Campbell (1962) and other workers have investigated the bacterial flora in the mouths of local species. Bacillus co/i with its usual antibiotic sensitivity range was isolated. In our major cases primary healing followed the administration of broad-spectrum antibiotics (gentamycin, cephalosporin and tetracycline) after appropriate surgery. Shark attack wounds are liable to heavy contamination with beach sand. Cases of clostridial infection following shark attack have been reported. Prophylactic cover with penicillin, tetanus toxoid or human antitetanus globulin is advised.
TREATMENT
OF SHARK
ATTACK
In Natal the general principles of treatment are those of Davies and Campbell (1962) but modified slightly for major trauma. Close co-operation with marine biologists, the voluntary lifeguards of the Surf Lifesaving Association, its local medical advisers and local general practitioners is essential Adequate photographic records are required. A shark attack on a swimmer or surfer causes terror. Panic may ensue. An efficient rescue service with lifeguards adequately trained in the general care of the victims of shark attacks will
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Shark Attack in Natal
lower the mortality rate by providing good primary care on the beach. A major injury, accompanied by profuse haemorrhage and crippling damage to a limb, sustained in heavy surf and strong currents at some distance from the shore, places heavy demands on rescue teams. In the 1973-74 series only two attacks caused major injuries, and no victim died. The victims were rescued by members of the Surf Lifesaving Association of South Africa (S.L.A.S.A.) following the policy agreed upon by the Accident Service, the medical advisers of S.L.A.S.A., the Oceanographic Research Institute and the Natal Anti-Sharks Measures Board. Local general practitioners helped to control bleeding on the beach and prevent chilling. Blood loss was partially restored by intravenous therapy before transferring the victim to hospital. Local treatment of the wounds resulted in primary healing in all 5 cases. Limited excision with primary suture under antibiotic cover was employed. One penetrating wound of the knee joint and the one below-knee amputation healed perfectly following primary closure. The amputation was indicated because of extensive skin, bone and muscle loss, accompanied by loss of a considerable length of both the musculocutaneous and posterior tibia1 nerves.
DISCUSSION Eficient preventive measures have markedly reduced the incidence of shark attack in Natal during the last decade. If damage to the protective net is suspected, bathing should be banned completely. Bathing on unprotected beaches along the Indian Ocean coast can be dangerous. The risk is greater when local conditions favour shark attacks. Bathing in warm water with a high optical density in the late afternoon appears to have been a contributory factor in our recent cases. Bathing should be banned as soon as dirty water invades the protected area. Light coloured surf boards are possibly attractive to sharks. The falling incidence of shark attack in the province with the largest number of bathers at risk (1965-73) suggests that an efficient system of protection for beaches is worth while. Twenty out of 21 cases (1965-73) took place in other areas without protection. Three of the recent series occurred on a beach in which the net system was suspect. Adequate training of lifeguards has contributed to the falling mortality rate of shark attacks along our coast. These teams are highly proficient in surf rescue and cardiopulmonary resuscitation, but lack experience in digital pulse compression,
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the use of local compression dressings, of the Esmarch tourniquet to control profuse bleeding, and the need for elevation of limbs. Many more people die on our beaches from drowning and cardiac failure than from shark attacks. Supplementary oxygen therapy is used for severely shocked patients, and ‘ space-blankets ’ of compressed aluminium foil prevent hypothermia and serve as improvised stretchers. Adequate equipment for treating severe shock on the beach is essential. In 1962 Dr. S. Feinberg of Margate, Natal designed a shock-pack, the ‘ Feinberg pack ’ which was placed in the clubhouse of every lifesaving team in Natal. The main contents were ‘ vacolitres ’ of normal saline, plasma and plasma diluent; intravenous sets, drugs, bandages, syringes and tourniquets, and their use reduced the mortality rate. At the recent World Congress of the Surf Lifesaving Association in Durban, the medical panel acknowledged the value of these packs and recommended that a modern version should be placed on every protected beach. Modifications included plastic packs of Ringer’s lactate solution (’ Viaflex ‘), intravenous giving-sets with a pump, modern intravenous cannulae for the proximal infusion of intravenous fluid in severely vasoconstricted patients, 4 per cent albumin solution in lieu of dried plasma and diluent, large rolls of absorbent gauze for dressing large tissue defects, disposable haemostats, and ‘ space blankets ‘. The tourniquet provided is an Esmarch bandage because of the high mortality associated with major injuries of the lower limb. This equipment is brought to the beach in a specially designed container, which provides a work surface on the sand. The equipment is designed for use by local doctors and rescue workers at the edge of the surf Supplementary oxygen is available for all teams. Premature movement of the victim from the beach to clubhouses or vehicles is actively discouraged. Most of those injured by sharks are fit young people who compensate well for severe bleeding. Efficient haemostasis with early, rapid restoration of the blood volume is stressed. Transfer to the clubhouse or ambulance is delayed for 30-60 min. in order to allow time for stabilization of the circulation. Premature movement of a casualty from the beach up steeply inclined dunes, rough handling in transit, and transport in poorly equipped vehicles may be contributory to a fatal outcome. EfJicient liaison within the rescue service is essential. Rescue teams are taught to carry the victims out of the surf in the ‘ head-down ’ position, start resuscitation, stop bleeding by direct
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Injury:
pressure, prevent hypothermia and send for medical assistance. Essential telephone numbers are listed on the Shark Attack Pack in each clubhouse. Splintage for severe bone injuries is taught. Carefully supervised sedation with dilute intravenous morphine solutions is advised. Lifeguards accompany their patients to the ambulance and to hospital. Helicopter transport direct to the Accident Unit can be arranged. The hospital-based Accident Services provides 24 hours advisory assistance but its success is dependent upon efficient primary care at the scene of the incident. Prior notification to the Hospital Accident Service ensures that senior staff are available to
continue resuscitation and to plan definitive care. Complete control of bleeding, ventilatory assistance, and adequate replacement of blood volume precede any local measures. Antitetanic and antibiotic therapy are commenced immediately. Efficiently applied dressings are left undisturbed. Local care of the wounds should be preceded by the taking of adequate photographs for the Shark Attack Files. Before wound cleansing, swabs are taken for bacteriological examination, culture and antibiotic sensitivity. Wounds are frequently contaminated by beach sand and other foreign matter, and require careful exploration for this reason as well as to determine the exact extent of the damage. In the common injuries following shark attack in Natal by Carcharodon leucas and related species, excision should be limited to obviously devitalized tissues, and it should be remembered that these are incised wounds and that the crushing component is minimal. Careful haemostasis is required. Articular and vascular injuries need primary repair. Covering by soft tissue should be provided for major nerve and tendon injuries, for which secondary suture is advised. Primary skin closure is recommended. If there is a large tissue defect, delayed primary grafting is recommended because there may be considerable oozing from injured muscle. Immediate amputation of an irreparably damaged limb may be required, and primary closure of flaps is recommended. Requests for reprints South Africa.
should
be addressed
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A. M. White,
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Postoperative care should follow usual surgical principles, and suitable antibiotic therapy should be continued for at least 10 days. Acknowledgements Our present methods are based on the extensive research of the late Professor David Davies and Dr G. D. Campbell at the Oceanographic Research Institute (Durban). The Director of the Oceanographic Research Institute (Dr Alan Heydorn) and the Director of the Oceanarium, Port Elizabeth (Dr John Bass) have kindly permitted access to their records on elasmobranch research and to their Shark Attack Files with very helpful advice on the natural history of these The Director of the Natal Antipredators. Shark Measures Board (Mrs. Beulah Davies) has kindly permitted access to the files on shark attacks and given valuable advice on the use of protective nets, the netting of sharks and the natural history of local species. We are indebted to the lifeguards and local doctors who initially treated these patients and to colleagues who have been responsible for many aspects of their definitive care. The permission of the Senior Medical Superintendent, Addington Hospital, to make use of the clinical records is gratefully acknowledged.
REFERENCES
BALDRIDGE,D. (1973), ‘ Shark attack against man ‘. Report to U.S. Navy Office of Naval Research (Code 484). CAMPBELL,G. D. (1968), Documents Geigy Nautilis. New York: Ardsley. - - DAVIES,D. H., and COPLEY,A. C. (1960), Med. Proc., 6, 612. DAVIES, D. H. (1960), S. Afr. Ass. Mar. Biol. Res. BUN., No. 1, 11-15. - - (1961), Ibid., No. 2, 23. - - and CAMPBELL,G. D. (1962), Jl R. nav. med. Ser., 3,3. DAVIS, M. (1974), personal communication. GILBERT,P. W. (1963a), Sharks and Survival. Boston: D. C. Heath and Co. - - (1963b), Ibid., p. 283. Department
of Surgery,
Addington
Hospital,
Durban,
P.O. Box 977.
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The British Journal of Accident Surgery
Shark attack
in Natal
J. A. M. White Principaf Surgeon, Department Addihgton H&pita/, Durban
of Hospital Services, Department
Summary
The injuries in 5 cases of shark attack in Natal during 1973-74 are reviewed. Experience in shark attacks in South Africa during this-period is discussed (1965% 73), and the value of protecting heavily utilized beaches in Natal with nets is assessed. The surgical applications of elasmobranch research at the Oceanographic Research Institute (Durban) and at the Headquarters of the Natal Anti-Shark Measures Board (Umhlanga Rocks) are described. Modern trends in the training of surf life-guards, the provision of basic equipment for primary resuscitation of casualties on the beaches, and the policy of general and local care of these patients in Natal are discussed.
INTRODUCTION DURING the period 1965-74 twenty-six cases of shark attack on humans were recorded in the
Shark Attack Files of the Oceanographic Research Institute (Durban) and the Natal AntiShark Measures Board. Five of these cases were recorded in Natal during 1973-74. The Shark Attack File was started by the late Professor David Davies and covered attacks from Mozambique to the Cape. The comprehensive data recorded on shark attacks were part of a research project on local elasmobranchs. In 1973 the file was taken over by the Anti-Shark Measures Board. Data from these sources regarding attacks have been used, together with personal observation in the series of 5 recent attacks in Natal (1973-74); evidence taken from voluntary life-guards, the records of local doctors who have given primary treatment to the victims, hospital records, and statements from the victims. HISTORY From 1940 to 1974 62 cases of shark attack on humans with a mortality of 40 per cent were
of Surgery,
recorded on the Indian Ocean coast of Southern Africa. Baldridge analysed data recorded in 1165 shark attacks throughout the world (Baldridge, 1973). The mortality rate has fallen in the last two decades to about 20 per cent (Gilbert, 1963a). Between 1944 and 1951 20 attacks took place on the beaches in the central city area of Durban. In 1952 the City of Durban began the present system of off-shore anti-shark nets which protect the popular beaches stretching for two miles north from the entrance to Durban Bay to the Umgeni River. The nylon mesh used to protect bathers and ‘ deep-water ’ surfers is suspended from off-shore buoys. Despite a continuing increase in the numbers using these beaches, no further major incidents have been recorded. In 1960 and 1962 a further series of attacks was reported from the 100 miles of beaches along the South Coast of Natal and led to most beaches being protected by nets. Between 1965 and 1973 only 1 major case of shark attack was reported from Natal, but 20 cases were recorded from unprotected areas in Zululand, Mozambique and the Cape. Campbell commented on the decrease of attacks along our coast despite a marked increase in the number of bathers, ‘ deep-water ’ surfers, skin and scuba divers (Campbell, 1968). During the abnormally wet summer (December, 1973-April, 1974) in Natal and Zululand, 5 cases were recorded of which 4 occurred on one unprotected beach 12 miles south of Durban. Two weremajor attacksand 3 were minor incidents. PREVENTIVE MEASURES AGAINST SHARK AlTACK Species of sharks known to be dangerous to man are found in large numbers along the coast of 187
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Southern Africa (Davies, 1960). Attacks have been reported from the cold waters of the Cape (15” C.) to the warm coral lagoons of Mozambique (21’C.). From 1965 to 1973 only 1 case was reported on a protected beach in Natal. Despite a heavier use of these beaches in the same period, 20 cases were reported from unprotected beaches in other sections of the Indian Ocean coast. In the present series (1973-74) 3 occurred on a ‘ protected ’ beach at a time when the net system was considered to be incomplete, and 2 were on ‘ open ’ beaches. Although the numbers involved are small, the remarkable decrease in shark attacks reported from Natal during the last two decades may be related to the rapid spread of efficient net systems throughout the Province. These net systems have replaced the fixed enclosures which were unsightly, liable to storm damage and corrosion, restrictive and potentially dangerous. Protective systems using submarine cables to produce repellent electrical fields have been developed locally but remain experimental. Preliminary work has been done on the use of acoustic techniques as a shark repellent (Davis, 1974). Nets are expensive, difficult to maintain and are not infallible, fatal attacks having been reported. The nets do not form a continuous barrier nor reach the sea bed. Approximately equal numbers of sharks are caught on the seaward and landward sides of the nets. Dangerous sharks therefore penetrate into the bathing areas. In the net systems of Natal, most sharks are trapped during rhe hours of darkness (Davis, 1974). The nets are thought to produce vibration patterns in the water which stimulate the highly sensitive vibration receptors of the sharks. Sharks are known to be attracted by certain vibration patterns in water, e.g. those set up by other sharks, hooked or injured fish. Sharks within the enclosed area turn out to sea and become entangled in the nets, are designed to trap sharks by their pectoral fins and tails. Once entangled they drown as they cannot move and breathe freely. FACTORS FAVOURING SHARK ATTACK Efficiently maintained nets reduced the number of sharks caught in the enclosed area by up to 80 per cent in a decade (Davies and Campbell, 1962). This fall is not matched by a corresponding fall in the numbers of sharks caught by local It is anglers in immediately adjacent areas. possible that sharks learn to avoid netted areas. Certain conditions are thought to predispose to shark attack (Gilbert, 1963a; Baldridge, 1973).
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a. Seasonal variation Numbers and species of sharks in the region are variable. Carcharinidue (Grey Sharks), Blue Pointers and others are attracted to the beach area of Durban during the autumn and winter months by the activities of the land-based whaling station at the entrance to Durban Bay. At other times there are fewer deep-water species in the inshore areas than indigenous Carcharinidae, which are present throughout the year. The Zambezi Shark (Curcharodon leucas) has been blamed for many attacks along the Natal coast, but there are many closely related species of Carcharinidae which are capable of inflicting injuries indistinguishable from those caused by Carcharodon leucas. In Natal swimming and surfing are possible throughout the year, but more people are at risk during the summer holidays (December to February). All cases reported during 1973-74 occurred during this period. b. Time of day/day of week Baldridge (1973) has indicated that the incidence of shark attack is related to the number of people at risk in the area at any one time. All our cases occurred in the afternoon. Three attacks were at dusk. There is a known tendency for our in-shore species to move toward net systems during a possible ‘ feeding surge ’ in the late afternoon, at a time when beaches are becoming deserted (Davis, 1974). c. Geographical and geomorphological features In Southern Africa the beaches of Natal have the highest numbers at risk throughout the year. Between 1965 and 1974 only 2 cases were reported from protected beaches, 1 on an open beach. Three were from a beach where the nets were temporarily suspect. In the same period 20 cases occurred elsewhere. All were from unprotected beaches and lagoons in Zululand, Mozambique and the Cape. All the recent attacks in Natal took place within 200 m. of the shore. One victim was actually sitting in very shallow water, the other 4 were attacked in an in-shore channel over 3 m. deep. Most Natal beaches shelve steeply to an in-shore channel which is separated from the open sea by a variable sandbar upon which the main surf starts to break. To reach the best surfing zone, this channel must be crossed. Even within promcted areas undetected sharks may come very close inshore by following these channels, and some become ‘ beached ’ during determined attacks.
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Meteorological
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All the recent cases occurred in clear weather with good surface visability. All the victims were Caucasian; all were attacked from below; 4 were attacked in the late afternoon or at dusk; 3 had light coloured surf boards and it is possible that, as seen from below the surface of the sea by an attacking shark, 4 of the victims presented a clear colour-contrast with their background. e. Hydrographic features In the recent cases in Natal, sea temperatures were over 21” C. (70” F.) at the time of the attack. Attacks in the Cape (1965-1973) were recorded at water temperatures of 15” C. Wounds in major cold water attacks at the Cape suggest that the Cape Blue Pointer (Carcharodon carcharias) was probably responsible for fatalities. This species represents less than 2 per cent of sharks in Natal waters (Davis, 1974). In Southern Africa water temperatures influence the species of shark responsible for attacks more than the actual incidence of attacks in a given area. The warm water throughout the year in Natal encourages bathers as well as Grey Sharks, which were suspect for two recent attacks in Natal. Turbidity of the surf was noted by Davies (Davies and Campbell, 1962) in 80 per cent of their series and during all our recent cases (1973-74), especially in two major attacks. In summer months heavy rainfall in the catchment areas of Natal’s large rivers causes flooding, and large quantities of dirty water discharge into the sea, contaminating many of the adjacent bathing areas. In-shore species of shark are attracted to turbid water and its contained food within protected areas (Davies, 1961). They have poor distant vision but good near vision in dim light. Decreased salinity of the water favours a high resident population of Grey Sharks, of which Zambezi Shark (Carcharodon Zeucas) is well known for its aggressive tendencies. These are found in the estuaries and lagoons along the coast and they have been found more than 100 miles up the Zambezi River from the coast. Decreased salinity is commonly recorded along our beaches during the summer floods, with their high water temperatures, increased turbidity, and maximal beach use. Depth of water at the time of the attack influences the type of injury and the mortality. Commercial shark fishermen at the Cape, and divers, have a different kind of injury from that of bathers and surfers who are attacked from below. This accounts for the heavy predominance of injuries to the lower limb in reported
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series (Baldridge, 1973). Mortality rates in attacks less than 30 m. from the shore are lower because assistance is more readily available to the victim. However in Natal another factor may be that the Cape Blue Pointer (Carcharodon carcharias) and the Tiger Shark (Galeocerdo cuvieri) are rare in these in-shore waters. These are very aggressive species in the Cape and inflict terrible injuries. The smaller Grey Sharks have different jaw and dental characteristics which influence the type of wounds commonly seen in Natal. The heavy male preponderance in reported series (Baldridge, 1973) is because men swim in deeper water, go further out and engage in ‘ deep-water ’ surfing. Four of our present patients were surfers and male. f. Colour
factors
All our recent cases were male Caucasians, who are most at risk, but other races have been attacked on several occasions. These men venture far from the shore during ‘ deep-water ’ surfing, using light coloured surf boards and presenting a high colour contrast on the surface. All were attacked from below and received leg injuries only. All were wearing short bathing trunks of varying colours. In one case the primary attack was made on the surf board and not on the surfer. Sharks have cone-poor retinae and probably do not see colour as we do (Gilbert, 1963b). Nevertheless, they can appreciate colour contrast, reflectivity and differences in light intensity. Experimental evidence suggests that International Orange (survival equipment) is attractive, but red and black are not attractive to sharks (Baldridge, 1973). g. Other factors Vibration patterns attract and repel sharks. One victim was paddling his feet in very shallow water at the time of the attack. The other 4 victims were either swimming on the surface or paddling their boards. All were at or near favourite fishing spots in turbid water which was contaminated by bait, offal or excrement. Significant bleeding followed each attack but the initial injury or bite was not followed by a determined attack or ‘ frenzy ‘. Injuries recorded in the Shark Attack Files (Fig. 1) indicate that there is a very great difference between a determined attack by a shark using a human as a source of food, and the tentative attacks made on 3 of the recent victims. In this group the shark appeared to be attracted to a surfer swimmer, investigated the source of the attraction but rejected him as a source of
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Fig. I.-Fatal outcome of frenzied attack by Cape Blue Pointer. Coarsely serrated wound edges caused by the widely separated teeth of this species which have lateral serrations.
Fig. 2.-Recent cases with penetrating wound of knee joint. The wound edges are sharp. The diameters of the two curving wounds suggested that the shark (possibly Carcharodon /emus) gripped the flexed knee from below.
food. Two of our 5 cases must therefore be classified as ’ aggressive close passes ’ and not definitive bites. Their injuries are compatible with rough contact with the points of sharp teeth during the shark’s initial scrutiny. Despite the profuse bleeding at some distance from the shore, no further attack was made on 4 of our cases or upon their rescuers during transit to the shore. Human blood does not seem to have the same attraction for sharks as whale, fish or shark blood (Baldridge, 1973).
before they were seized by the leg. Both victims recall striking at the shark.
THE
SHARK
ATTACK
One victim was seized by the toes and forefoot in very shallow water. Two were seized from below and sustained definite bites. Two sustained glancing blows and lacerated wounds. The injuries in all the victims formed a single pattern. Two recent victims clearly described the ‘ bump ’ made by the initial contact with the shark as a sharp blow which threw them out of the water
Fig. 3.-Recent case showing loss of tissue from leg possibly caused by Carcharodon leucns. Fine serrations in the skin edge are seen.
SPECIES
OF SHARK
RESPONSIBLE
Direct identification was impossible. In two aggressive close passes the linear wounds could have been made by any species baring its teeth during scrutiny of a victim. In the two major attacks the character and the differing diameter of the upper and lower wounds suggested not only the direction of the attack but the species of shark responsible (Figs. 2 and 3). The finely serrated wound edges in the skin, tibia and knee joint of these cases suggested that the shark responsible was a Grey Shark (Carcharinus Ieucas or related species), because these sharks have very small pointed teeth set close together in a single row with very fine lateral serrations (Fig. 4). These teeth produce a relatively clean-cut wound of skin, fascia, muscle and bone which contrasts sharply with the rough edged wounds inflicted by
Fig. 4.-Teeth of Carchavodon /emus lateral serrations.
showing fine
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Fig. S.-Jaws and teeth of Carcharodon carcharias showing widely separated teeth with lateral serrations.
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damage to a limb, a small boat or a surf board, but the type of wound may vary from a tangential injury (’ close pass ‘) to a definitive bite. Tentative bites of the limbs account for more than 70 per cent of the wounds in the Shark Attack Files. In 70 per cent of surface swimmers the lower limb only was involved. A shark making an aggressive ‘ close pass ’ can be seen to bare the razor-sharp teeth of its upper jaw, which inflict lacerations, incised wounds and loss of tissue. Davies and Campbell (1962) discussed alternative causes of this type of wound by fish in Natal waters (snoek, barracuda or Spanish mackerel). In a recent case a large Saw Fish penetrated the netting system and inflicted a series of three parallel incised wounds on the anterolateral aspect of the thigh of a swimmer in deep water (Davis, 1974). The distance between the three parallel wounds corresponded exactly to the distance between the serrated edge of the bill of a large Saw Fish. Definitive wounds follow a determined attack. The appearance of the wound varies according to the part or parts of the body seized by the shark and the size of the species responsible. Severe lacerations, loss of soft tissue, amputations,
the Cape Blue Pointer, which has larger teeth, set widely apart (Fig. 5). These cause coarsely serrated wound edges (see Fig. 1). Elasmobranch teeth are cartilaginous but radio-opaque. They can be seen in radiographs as dense triangular opacities in the comminuted bones and adjacent soft tissues following severe injury. In the recent cases all radiographs were negative. Small fragments of finely serrated teeth were recovered from the amputated section of the tibia in one of our recent cases, but were too small for accurate identification of the species responsible for the attack (Davis, 1974). Campbell and others (Campbell, Davies and Copley, 1960) described the appearances of the wounds inflicted by the Ragged Tooth Shark (Curcharius taut-us) (Fig. 7). In one case in the Shark Attack File, the recovery of a single tooth from the femur of the victim enabled the species responsible to be identified as a Tiger Shark (Galeocerdo cuvieri)(Figs. 4,5,6 and 7.) LOCAL CHARACTERISTICS OF SHARK ATTACK WOUNDS Davies and Campbell (1962) indicated that a large Grey Shark has tremendous power in its jaws and is perfectly capable of throwing a young adult out of the water. Its jaws can inflict severe
Fig. 6.-Jaws and teeth of Galeocerdo cuvieri showing closely set teeth with characteristic recurving tip.
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Crushing of tissue is minimal. Profuse and continuing haemorrhage is common. Campbell and others (1960) described the only case of a Ragged Tooth Shark attack in Natal. The species is rare in these waters. Its long pointed teeth are set in irregular rows in both the upper and lower jaws (Fig. 7). These inflicted an avulsion type of injury on the pelvis and abdomen with visceral penetration. The long curved teeth have no lateral serrations and therefore do not cut. As might be expected the wounds were markedly irregular. Puncture wounds may be expected from this type of shark. Deep bacterial contamination is likely. Large Cape Blue Pointers (Cuvchavodon carcharius) inflict gross lacerated wounds with coarsely serrated edges caused by their widely spaced triangular teeth with sharp lateral serrations (Fig. 1). The wounds inflicted by the Tiger Shark (Galeocerdo cuvieri) have no special characteristics. The large teeth are closely set, laterally serrated but have a curving tip which incriminates the species if a tooth can be recovered from the victim. Fig. 7.-Jaws and teeth of Carcharias taitrus showing multiple rows of widely separated long backward curving teeth. comminuted fractures, etc., are recorded with muscle, tendon, nerve and vascular injuries. Injuries of the trunk form only 5 per cent of large series (Davis, 1974). Over 70 per cent of wounds are found to be single (Baldridge, 1973), suggesting one attack or bite. In wounds of the limbs a ‘ step-pattern ’ is sometimes seen. The common Grey Sharks of Natal (Curcharodon Zeucas and related species) have extremely sharp pointed teeth with fine lateral serrations set in a single row in the upper and lower jaws which have a different maximum diameter (Fig. 4). The tine lateral serrations impart a cutting edge resembling that of the Gigli saw. Although the wounds inflicted by these species have the gross characteristics of a lacerated wound, the wound edge in skin and bone is finely serrated (Fig. 3). In the more proximal injuries of the leg, thigh and buttock, the tissue is firmly gripped by the upper and lower jaws and marked accordingly (Fig. 2). The cutting action is effected by violent lateral movements of the body and tail, while the head is stabilized by the pectoral fins. A clean-cut edge to the wounds results with minimal damage to tissue which is not immediately adjacent to the line of severance.
BACTERIOLOGICAL CHARACTERISTICS AlTACK
IN SHARK
Davies and Campbell (1962) and other workers have investigated the bacterial flora in the mouths of local species. Bacillus co/i with its usual antibiotic sensitivity range was isolated. In our major cases primary healing followed the administration of broad-spectrum antibiotics (gentamycin, cephalosporin and tetracycline) after appropriate surgery. Shark attack wounds are liable to heavy contamination with beach sand. Cases of clostridial infection following shark attack have been reported. Prophylactic cover with penicillin, tetanus toxoid or human antitetanus globulin is advised.
TREATMENT
OF SHARK
ATTACK
In Natal the general principles of treatment are those of Davies and Campbell (1962) but modified slightly for major trauma. Close co-operation with marine biologists, the voluntary lifeguards of the Surf Lifesaving Association, its local medical advisers and local general practitioners is essential Adequate photographic records are required. A shark attack on a swimmer or surfer causes terror. Panic may ensue. An efficient rescue service with lifeguards adequately trained in the general care of the victims of shark attacks will
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lower the mortality rate by providing good primary care on the beach. A major injury, accompanied by profuse haemorrhage and crippling damage to a limb, sustained in heavy surf and strong currents at some distance from the shore, places heavy demands on rescue teams. In the 1973-74 series only two attacks caused major injuries, and no victim died. The victims were rescued by members of the Surf Lifesaving Association of South Africa (S.L.A.S.A.) following the policy agreed upon by the Accident Service, the medical advisers of S.L.A.S.A., the Oceanographic Research Institute and the Natal Anti-Sharks Measures Board. Local general practitioners helped to control bleeding on the beach and prevent chilling. Blood loss was partially restored by intravenous therapy before transferring the victim to hospital. Local treatment of the wounds resulted in primary healing in all 5 cases. Limited excision with primary suture under antibiotic cover was employed. One penetrating wound of the knee joint and the one below-knee amputation healed perfectly following primary closure. The amputation was indicated because of extensive skin, bone and muscle loss, accompanied by loss of a considerable length of both the musculocutaneous and posterior tibia1 nerves.
DISCUSSION Eficient preventive measures have markedly reduced the incidence of shark attack in Natal during the last decade. If damage to the protective net is suspected, bathing should be banned completely. Bathing on unprotected beaches along the Indian Ocean coast can be dangerous. The risk is greater when local conditions favour shark attacks. Bathing in warm water with a high optical density in the late afternoon appears to have been a contributory factor in our recent cases. Bathing should be banned as soon as dirty water invades the protected area. Light coloured surf boards are possibly attractive to sharks. The falling incidence of shark attack in the province with the largest number of bathers at risk (1965-73) suggests that an efficient system of protection for beaches is worth while. Twenty out of 21 cases (1965-73) took place in other areas without protection. Three of the recent series occurred on a beach in which the net system was suspect. Adequate training of lifeguards has contributed to the falling mortality rate of shark attacks along our coast. These teams are highly proficient in surf rescue and cardiopulmonary resuscitation, but lack experience in digital pulse compression,
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the use of local compression dressings, of the Esmarch tourniquet to control profuse bleeding, and the need for elevation of limbs. Many more people die on our beaches from drowning and cardiac failure than from shark attacks. Supplementary oxygen therapy is used for severely shocked patients, and ‘ space-blankets ’ of compressed aluminium foil prevent hypothermia and serve as improvised stretchers. Adequate equipment for treating severe shock on the beach is essential. In 1962 Dr. S. Feinberg of Margate, Natal designed a shock-pack, the ‘ Feinberg pack ’ which was placed in the clubhouse of every lifesaving team in Natal. The main contents were ‘ vacolitres ’ of normal saline, plasma and plasma diluent; intravenous sets, drugs, bandages, syringes and tourniquets, and their use reduced the mortality rate. At the recent World Congress of the Surf Lifesaving Association in Durban, the medical panel acknowledged the value of these packs and recommended that a modern version should be placed on every protected beach. Modifications included plastic packs of Ringer’s lactate solution (’ Viaflex ‘), intravenous giving-sets with a pump, modern intravenous cannulae for the proximal infusion of intravenous fluid in severely vasoconstricted patients, 4 per cent albumin solution in lieu of dried plasma and diluent, large rolls of absorbent gauze for dressing large tissue defects, disposable haemostats, and ‘ space blankets ‘. The tourniquet provided is an Esmarch bandage because of the high mortality associated with major injuries of the lower limb. This equipment is brought to the beach in a specially designed container, which provides a work surface on the sand. The equipment is designed for use by local doctors and rescue workers at the edge of the surf Supplementary oxygen is available for all teams. Premature movement of the victim from the beach to clubhouses or vehicles is actively discouraged. Most of those injured by sharks are fit young people who compensate well for severe bleeding. Efficient haemostasis with early, rapid restoration of the blood volume is stressed. Transfer to the clubhouse or ambulance is delayed for 30-60 min. in order to allow time for stabilization of the circulation. Premature movement of a casualty from the beach up steeply inclined dunes, rough handling in transit, and transport in poorly equipped vehicles may be contributory to a fatal outcome. EfJicient liaison within the rescue service is essential. Rescue teams are taught to carry the victims out of the surf in the ‘ head-down ’ position, start resuscitation, stop bleeding by direct
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pressure, prevent hypothermia and send for medical assistance. Essential telephone numbers are listed on the Shark Attack Pack in each clubhouse. Splintage for severe bone injuries is taught. Carefully supervised sedation with dilute intravenous morphine solutions is advised. Lifeguards accompany their patients to the ambulance and to hospital. Helicopter transport direct to the Accident Unit can be arranged. The hospital-based Accident Services provides 24 hours advisory assistance but its success is dependent upon efficient primary care at the scene of the incident. Prior notification to the Hospital Accident Service ensures that senior staff are available to
continue resuscitation and to plan definitive care. Complete control of bleeding, ventilatory assistance, and adequate replacement of blood volume precede any local measures. Antitetanic and antibiotic therapy are commenced immediately. Efficiently applied dressings are left undisturbed. Local care of the wounds should be preceded by the taking of adequate photographs for the Shark Attack Files. Before wound cleansing, swabs are taken for bacteriological examination, culture and antibiotic sensitivity. Wounds are frequently contaminated by beach sand and other foreign matter, and require careful exploration for this reason as well as to determine the exact extent of the damage. In the common injuries following shark attack in Natal by Carcharodon leucas and related species, excision should be limited to obviously devitalized tissues, and it should be remembered that these are incised wounds and that the crushing component is minimal. Careful haemostasis is required. Articular and vascular injuries need primary repair. Covering by soft tissue should be provided for major nerve and tendon injuries, for which secondary suture is advised. Primary skin closure is recommended. If there is a large tissue defect, delayed primary grafting is recommended because there may be considerable oozing from injured muscle. Immediate amputation of an irreparably damaged limb may be required, and primary closure of flaps is recommended. Requests for reprints South Africa.
should
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Postoperative care should follow usual surgical principles, and suitable antibiotic therapy should be continued for at least 10 days. Acknowledgements Our present methods are based on the extensive research of the late Professor David Davies and Dr G. D. Campbell at the Oceanographic Research Institute (Durban). The Director of the Oceanographic Research Institute (Dr Alan Heydorn) and the Director of the Oceanarium, Port Elizabeth (Dr John Bass) have kindly permitted access to their records on elasmobranch research and to their Shark Attack Files with very helpful advice on the natural history of these The Director of the Natal Antipredators. Shark Measures Board (Mrs. Beulah Davies) has kindly permitted access to the files on shark attacks and given valuable advice on the use of protective nets, the netting of sharks and the natural history of local species. We are indebted to the lifeguards and local doctors who initially treated these patients and to colleagues who have been responsible for many aspects of their definitive care. The permission of the Senior Medical Superintendent, Addington Hospital, to make use of the clinical records is gratefully acknowledged.
REFERENCES
BALDRIDGE,D. (1973), ‘ Shark attack against man ‘. Report to U.S. Navy Office of Naval Research (Code 484). CAMPBELL,G. D. (1968), Documents Geigy Nautilis. New York: Ardsley. - - DAVIES,D. H., and COPLEY,A. C. (1960), Med. Proc., 6, 612. DAVIES, D. H. (1960), S. Afr. Ass. Mar. Biol. Res. BUN., No. 1, 11-15. - - (1961), Ibid., No. 2, 23. - - and CAMPBELL,G. D. (1962), Jl R. nav. med. Ser., 3,3. DAVIS, M. (1974), personal communication. GILBERT,P. W. (1963a), Sharks and Survival. Boston: D. C. Heath and Co. - - (1963b), Ibid., p. 283. Department
of Surgery,
Addington
Hospital,
Durban,
P.O. Box 977.