- Email: [email protected]
Onchocerca Gutturosa (Neumann, 1910) Infection in Sudanese Cattle
Br. vet.
J.
(1975),
13 1 ,
76
ONCHOCERCA GUTTUROSA (NEUMANN, 1910) INFECTION IN SUDANESE CATTLE By M. F.
HUSSEIN,*
O.
ABDEL G.
S.
NUR,
M. S.
GASSOUMA,
t
AND
NELSON+
*Faculty of Veterinary Science, P.O. Box 32, Khartoum North, Sudan. t Ministry of Health, Khartoum, Sudan. tLondon School of Hygiene and Tropical Medicine, London WeIE 7HT, England
SUMMARY
Onchocerca gutturosa, previously unknown to exist in the Sudan, was found in I 70 of 248 male and female cattle examined at Omdurman Central Abbatoir. The parasite was confined to the connective tissue of the nuchal ligament, where it usu ally caused severe tissue reaction. Its microfilariae were found in different concentrations in the skin of the ear, tail, umbilicus, scrotum or udder. Sometimes, pathological lesions due to the latter larvae were encountered in the skin. Invariably, there was a mixed infection with O. armillata. INTRODU C TION
Onchocerca gutturosa (Neumann, I9IO) occurs in the nuchal and sometimes in the rumeno-splenic ligaments of cattle in many parts of the world (Eichler & Nelson, 1971 ). The adult parasites are unobtrusive, and usually pass unnoticed (Nelson, I966), but the microfilariae are blamed for causing severe dermatitis in cattle in the Far East (Niimi & Kuono, 1954) and some parts of Africa (H erin, Thrienpont & Fain, 1955). In the U.S.S.R., they are believed to be r esponsible for considerable damage to bovine hides (Gnedina, I959) ; by involving the skin of the udder, they are also said to cause lowering of milk yield and retention of milk, which may subsequently lead to mastitis (Balmichev 1966 ). Since O. gutturosa adults are found in ligaments not usually examined post mortem, their existence may not necessarily attract attention. This may well be one of the reasons for the absence of previous records of the parasite in the Sudan. In the following report, the occurrence of O. gutturosa in Sudanese cattle is recorded, and some data are given on the rate of infection, microfilarial densities in the skin and associated pathological lesions. Other investigations d ealing with the transmission of the parasite in the Sudan will be reported later.
ONCHOCERCA GUTTUROSA IN SUDANESE CATILE
77
MATERIALS AND METHODS
Random examination of 180 male and 68 female cattle of different age groups was made in order to d etermine the occurrence of O. gutturosa adults. At the same time, a search was made for the adults of O. armillata in the aortic wall. The animals were seen at Omdurma n Central Abbattoir during several visits extending between J anuary- D ecember 1972. It was not intended to study the morphology of O. gutturosa in d etail; in order to confirm identification, however, male worms and pieces of femal e worms, up to 40 em long, were removed from infected nuchal ligaments and examined while fresh using a dissecting microscope. Also, the general morphology of microfila riae was noted before estimating microfilarial skin d ensities, in order to exclude other filarial larvae. For this purpose, sufficient numbers of Microfilaria gutturosa were obtained from the uterus of worms and from the skins of parasitized cattle; these were examined by a light microscope either as fresh preparations or after staining with Leishman's stain or brilliant cresyl blue. Microfilariae ex utero were collected by placing teased parts of gravid female parasites in petri dishes containing physiological saline for periods of from 30 min to I h, followed by removal of the females' r emnants, centrifugation of saline, and examination of the sediments. "Skin" microfilariae, on the other hand, were collected after incubating finely sliced pieces of skin in physiological saline for several hours, centrifugation, and sedimentation. Both the adult worms and the microfilariae were found to conform in morphology with the accepted description of the species. The relative d ensities of microfilariae in different parts of the skin were subsequently determined. Since the objective was primarily to form an opinion on distribution patterns of these larvae, only a crude m ethod of counting was pursued. From each of 33 male and female cattle with known infection, measured areas, approximately I cm 2, were taken from the skin of the ear, tail, umbilicus and udder or scrotum. These areas were comparable in thickn ess, and were cut into smaller portions and incubated overnight in plastic containers with an appropriate quantity of physiological saline. The number of microfilariae in the whole quantity of saline was then counted, and several washes made to include any r emaining larvae. A study of the gross and the histopathological lesions in the infected animals was also made. Microscopical sections were prepared after processing in paraffin, and were stained with Haematoxylin and eosin, Gomori's reticulin stain and periodic-acid Schiff reagent. RE SU LT S
Parasitological findings Table I summarizes the results of the survey carried out to d etermine the incidence of onchocerciasis in Sudanese cattle. The overall incidence of O. gutturosa in male and female animals was found to be approximately 68'5 per cent. The worms were located exclusively in the connective tissue of the nuchal liga ment, and none was found in the rumeno-splenic ligament or elsewh ere,
BRITISH VETERINARY JOURNAL,
131,
1
T AB LE 1 INCIDENCE
OF
Onchocerca gutturosa
AND
O. arm illata
ADULTS
IN
SUDANESE
CATTLE
Number irifected
Males Females Total
Number examined
0. gutturosa
0. armillata
180 68 248
121 (67 .2%) 49 (72. 1 %) 170 (68·5%)
138 (76.7%) 61 (89·7%) 199 (80 ·2%)
Note: Percentage incidence is given between brackets.
despite a careful search. Similarly, the aortic parasite, O. armillata, was extremely common; it occurred in more than 80 per cent of the animals seen, including all of those infected with O. gutturosa. O. armillata was found in nodules and tunnels within the aortic wall, particularly at the region of the aortic arch; like O. gutturosa, its incidence was higher in female cattle. In both cases, there was apparently no seasonal variation in incidence of the parasites, and most of the non-infected animals were relatively young in age. In the skin, two types of microfilariae were encountered. One type, which was only rarely observed, was sheathed and had well-developed striations and other morphological features consistent with those of Setaria spp. It appeared that these microfilariae were released from broken blood vessels when the skin was cut. On subsequent examination of some animals, a low incidence of S. labiatopapillosa adults was noted in the peritoneal cavity. However, the parasite was not systemically searched for and was therefore excluded from this survey. The other type of micro filariae, which was far more predominant, was identified as that of O. gutturosa, and accordingly counted. It occurred in all parts of the skin examined, with the highest densities in the skin of the ear, followed by the scrotum (or udder), the tail and least in the umbilicus (Table II ) .
Pathological findings Nuchal ligament. The connective tissue of affected ligaments was reddish or pinkish, oedematous and sometimes haemorrhagic, showing irregular, roughened areas and engorged superficial venules, particularly on the inner surface where the worms were located. The parasites were almost invariably confined to the funicular part of the ligament, being either concealed in the connective tissue, or, less commonly, forming hard, raised nodules resembling lymph nodes. These nodules revealed a greyish core of necrotic tissue in which portions of the worms were found embedded. Sometimes, the parasites appeared thicker than normal as a result of surrounding tissue reaction. Calcified worms were also commonly encountered, and were easily recognized by virtue of their whitish calcareous appearance (Fig. I). In histopathological preparations, cross-sections of female worms were often seen in the connective tissue (Fig. 2). They were sometimes intact, showing no evidence of degeneration, and many of them revealed parts of their uteri filled with large numbers or microfi lariae and embryonated eggs. As a result
a
~
:J:: a
~ ~
Q
TABLE II
Onchocerca gutturosa
(Mean counts of microfilariae per
I
22 12
Sex
Ear
Umbilicus
M
38"6 ± 18"6 (7"9-7 6 "5) 26"4 ± 10"9 (7" 1-44 "2)
1"4 2"6 (0"0- 5"8) 2"3 ± 2"2
F
Note : ranges are given between brackets"
±
(O"O- H)
~
( ± S"D" )
Scrotum
Tail
±
3 "2 ± 4"1 (0"0- 17"8) 4"0 ± 2"9 (0 "5- 1 7"3 )
11 "5
c::: ...., ....,
cm2 of skin)
Mean cOllcentration of microfilariae Number of animals
G
INFECTION IN SUDANESE CATTLE
11"1
(0"2- 37"6)
Udder
a f;:: ::;'
6"9 ± 4"7 (0"4- 33"6)
en
c:::
~
>Z
t>1 en t>1
o
~
>-l t"" t>1
-..t
<.0
80
BRITISH VETERINARY JOURNAL,
131, I
Fig. I. Showing calcified parts of O. gutturosa adults in the connective tissue of nuchal ligament.
of fixation, the parasites were shrunken and appeared surrounded each by an empty crescentric space lined by a hyaline wall. It was obvious, however, that the worms occupied tortuous, intercommunicating tunnels, often surrounded by histiocytes, lymphocytes and eosinophils, and supported by a delicate reticulum of fibrous connective tissue (Fig. 3). Sometimes, multinucleated giant cells were found in the vicinity of the parasites, and, at other times, following disintegration and absorption of the latter, a dense core of degenerated eosinophils was seen in the centre of well-developed lesions (Fig. 4). Also, eosinophils
Fig.
2.
Showing cross-sections of parasites in the connective tissue of nuchal ligament.
H. & E. x 60.
ONCHOCERCA GUTTUROSA IN SUDANESE CATTLE
81
Fig. 3. A g ra nulomatous resection with fibrosis around O. gutturosa in nuchal ligament.
H. & E.
X 1 20.
were sometimes found accumulating on the cuticle of the parasites. In some sections, an interesting finding was the occurrence of faintly acidophilic areas of fibrinoid change containing few, vacuolated histiocytes and remnants of microfilariae, around worms (Fig. 5). In still other cases, only calcified parasites were foun d which were, nonetheless, surrounded by m arked tissue reaction . This reaction seemed to have been present even before mineralization of the parasites, a nd the lesions therefore exhibited calcified centres with surrounding often heavy, accumulation of inflammatory cells. Occasionally, such lesions lay adjacent to each other, giving a characteristic "follicular" appearance. Calcium deposits, topographically unrelated to worms, were also found in the
Fig. 4. Section showing intense, darkly-stained zone of degenerated eosinophils in the centre of granuloma in the connective tissue of nuchal ligament. H. & E. X 120.
BRITISH VETERINARY JOURNAL,
1 31, 1
Fig. 5. Section of connective tissue of nuchal ligament showing zone of fibrinoid reaction around parasite, beside accumulation of inflammatory cells. H. & E. X 120.
rest of the connective tissue, but the latter more often revealed a loose, oedematous and richly vascularized appearance, with some areas undergoing marked mucoid degeneration, and others showing an infiltration of histiocytes, eosinophils and large numbers of maturing fibroplasts. Similar infiltration was also seen around small blood vessles in the connective tissue. Within the substance of the ligament itself, however, neither worms nor PAS-positive material could be demonstrated, although a heavy accumulation of lymphocytes was occasionally seen, with cells being mainly found in the interstices between fibrou s bundles of the ligament.
Fig. 6. Skin showing patchy accumulation of inflammatory cells. H. & E.
X 120.
ONCHOCERCA GUTTUROSA IN SUDANESE CATTLE
Skin. Although pathological lesions that could be attributed to onchocerciasis were not seen on gross examination of the skin, microscopical sections often revealed an inflammatory reaction, associated with the presence of large numbers of microfilariae in the dermis (Fig. 6). The latter larvae were either found within the inflamed areas themselves or were free from local cellular reaction and lay intact, just below the germinal cell layer of the epidermis. Typically, however, there was patchy or widespread accumulation of round cells and eosinophils in the superficial dermal layer or more deeply and around hair [olicles and cutaneous blood vessels. DISCUSSION
It is difficult to make a true assessment of the significance of bovine onchocerciasis in the Sudan, owing to the limited observations recorded above, but there is no doubt that both O. gutturosa and O. armillata are common helminths of cattle in the country. As was pointed out by Eichler & Nelson (1971), however, there appears to be no definite clinical manifestations associated with the presence of adult stages of the former species in the nuchal ligament, despite the severity of the local tissue reaction. On the other hand, the possibility that th e microfilariae may account for severe lesions in the skin o[ infected cattle, as was found in some of the present cases, and previously recorded by others (Niimi & Kuono, 1954; Herin et al., 1955), indicates that a more thorough investigation of the problem should be undertaken. From a parasitological standpoint, it was interesting to note that O. gutturosa adults were confined to the connective tissue of the nuchal ligament. This degree of "site-specificity" was also observed by Clarkson (1964) in a study of O. gutturosa in East Africa, but Eichler & Nelson (1971) suggested that it may vary with different geographical strains of the parasite. In some countries, the worms are also found in the connective tissue between the spleen and the rumen of infected animals. On the other hand, some authors (Johnston, 192 I; Strong et al., 1937) regarded the latter form (i.e. the rumeno-splenic form) as a different species, for which the name O. linealis was retained, and others disagreed on account that no obvious dimorphism was seen (Caballaro, 1945). Recently, Eichler (1 973), studying the systematics of O. gutturosa in British animals, also suggested that difference in the morphology of nuchal and rumeno-splenic forms of the parasite were variable and inadequate to justify considering them as two distinct species. Yet, he proposed that the controversy could "only be resolved by an experiment to see whether or not microfilariae, whatever their origin, are equally capable of undergoing final development either in the neck or between the rumen and spleen of cattle" . The other species of Onchocerca mentioned in this report, O. armillata, was recorded in the Sudan by Malek (1958). Later, detailed investigations of its histopathological and histochemical aspects were carried out (Mostafa et al., 19 66 ; Cerny, Mostafa & Cerna, 1966). However, these authors made no mention of possible clinical effects the parasite might exert on the animals. In Indi a, Patnaik (1962) describ ed severe paralysis and ocular lesions, associated
BRITISH VETERINARY JOURNAL, 131, I
with aberpant localization of microfilariae in the spinal cord and eye respectively, in cattle heavily infected with this parasite. It is not unlikely that similar cases also exist in the Sudan without their real cause being demonstrated. REFERENCES BALMICHEV, N. P. (1966) . Veterinar~a, 43(2), 54 (in Russian) . CABALLERO, C. E. (1945). An Inst. Bioi. 16,367. CERNY, L., MOSTAFA, I. E. & CERNA, j. (1966) . Sudan Medical Journal, 4 (4), 187. CLARKSON, M. j. ( 1964). Ann. trop. Med. Parasit. 58, 153. EICHLER, D. A. & NELSON, G. S. (1971 ) . J. Helminth . X LV(2!3), 245. EICHLER, D . A. (1973) ' J. Helminth. XLVII( I), 89. GNEDINA, M. P. (1959) . Byuleten Nauchno-Teknicheskoi Informratsii Vsesoyuznugo I nstituta Gelminthologii im K. 1. Skryabina, NO.5, I I (in Russian). HERIN, V., THRIENPONT, D. & FAIN, A. (1955) . Annis. Soc. beige Med. trop. 35, 523. JOHNSTON, T. M. ( 192 1). Trans. R. Soc. S. Aust. 45, 231. MALEK, E. (1958). J. Parasit. 44 (4, Sect. 2), 30. MOSTAFA, I. E., EL HASSAN, A. M., CERNA, j. & CERNA, L. (1966). Sudan Med. J. 4, 147. NUMI, D. & KUONO, I. ( 1954), Bull. Fac. Agric. Kagoshima Univ. No. 3, 151 (in japanese; English summary, p .162). NELSON, G. S. ( 1966) . Helm. Abs. 35, 31 I. PATNAIK, B. (1962 ). J. Helminth. XXXVI(3), 313. STRONG, R. P., BECQ.UAERT, j. C. , SANGROUND, j. H. & MUNOZ, O . M. ( 1937). Onchocercosis With Special Riference to the Central American Form of the Disease, 234 pp. Harvard University Press. (Accepted for publication 2 I February 1974) Onchocerca gutturosa (Neuntann, 1910) infection chez Ie betail soudanais (Hussein et al.) ResUDle. On a decouvert Onchocerca gutturosa, jusqu'alors inconnu au Soudan, chez 170 des 248 animaux males et femelles examines au "Omdurman Central Abattoir". L e parasite ne se trouvait que dans Ie tissu connectif du ligament nucal, OU, d'habitude, il provoquait une reaction severe. On trouva les microfilaires, dans des concentrations variees, dans la peau de I'oreille, de la queue, de I'ombilic, du scrotum ou du pis. On rencontra parfois des lesions pathologiques dues aces larves dans la peau. Invariablement, I'infection etait compliquee par O. armillata . Infektion sudanesischer Rin der ntit Onchocerca gutturosa (NeUD1ann, 1910) (Hussein et al.) Zusantntenfassung. Onchocerca gutturosa friiher unbekannt im Sudan wurde bei 170 von 248 im Omdurman Zentralschlachthof untersuchten Ochsen und Kiihen gefunden. Das Vorkommen der Parasiten beschrankte sich auf das Bindegewebe des lig.nuchae, wo es meistens schwere Gewebereaktionen verursacthe. Mikrofilarien fanden sich in verschiedenen Konzentrationen in der Haut von Ohren, Schwanz, Nabe!, Scrotum und Euter. Zuweilen sah man auch pathologische Laesionen in d er Haut, infolge von spater sich entwickelnden Larven. In jedem Fall bestand eine Mischinfektion mit O. armillata. Infecciones debidas a Onchocerca gutturosa (NeUD1ann, 1910) en ganados sudaneses (Hussein et al.) ResUD1en. Se encontr6 Onchocerca gutturosa, previamente desconocida en el Sudan, en 170 de 248 toros y vacas examinados en el matadero central de Omdurman. EI paras ito se ha1l6 confinado en e! tejida conectivo del ligamento nucal, en que normal mente causa reacciones tisulares muy fuertes. Se encontraron sus microfilarias en distintas concentraciones en la piel de la oreja, cola, ombligo, escroto 0 ubre. A veces se encontraron en la piellesiones patol6gicas debidas a las larvas de estas ultimas. Invariablemente, la infecci6n estuvo unida a infecci6n por O. armillata.
J.
(1975),
13 1 ,
76
ONCHOCERCA GUTTUROSA (NEUMANN, 1910) INFECTION IN SUDANESE CATTLE By M. F.
HUSSEIN,*
O.
ABDEL G.
S.
NUR,
M. S.
GASSOUMA,
t
AND
NELSON+
*Faculty of Veterinary Science, P.O. Box 32, Khartoum North, Sudan. t Ministry of Health, Khartoum, Sudan. tLondon School of Hygiene and Tropical Medicine, London WeIE 7HT, England
SUMMARY
Onchocerca gutturosa, previously unknown to exist in the Sudan, was found in I 70 of 248 male and female cattle examined at Omdurman Central Abbatoir. The parasite was confined to the connective tissue of the nuchal ligament, where it usu ally caused severe tissue reaction. Its microfilariae were found in different concentrations in the skin of the ear, tail, umbilicus, scrotum or udder. Sometimes, pathological lesions due to the latter larvae were encountered in the skin. Invariably, there was a mixed infection with O. armillata. INTRODU C TION
Onchocerca gutturosa (Neumann, I9IO) occurs in the nuchal and sometimes in the rumeno-splenic ligaments of cattle in many parts of the world (Eichler & Nelson, 1971 ). The adult parasites are unobtrusive, and usually pass unnoticed (Nelson, I966), but the microfilariae are blamed for causing severe dermatitis in cattle in the Far East (Niimi & Kuono, 1954) and some parts of Africa (H erin, Thrienpont & Fain, 1955). In the U.S.S.R., they are believed to be r esponsible for considerable damage to bovine hides (Gnedina, I959) ; by involving the skin of the udder, they are also said to cause lowering of milk yield and retention of milk, which may subsequently lead to mastitis (Balmichev 1966 ). Since O. gutturosa adults are found in ligaments not usually examined post mortem, their existence may not necessarily attract attention. This may well be one of the reasons for the absence of previous records of the parasite in the Sudan. In the following report, the occurrence of O. gutturosa in Sudanese cattle is recorded, and some data are given on the rate of infection, microfilarial densities in the skin and associated pathological lesions. Other investigations d ealing with the transmission of the parasite in the Sudan will be reported later.
ONCHOCERCA GUTTUROSA IN SUDANESE CATILE
77
MATERIALS AND METHODS
Random examination of 180 male and 68 female cattle of different age groups was made in order to d etermine the occurrence of O. gutturosa adults. At the same time, a search was made for the adults of O. armillata in the aortic wall. The animals were seen at Omdurma n Central Abbattoir during several visits extending between J anuary- D ecember 1972. It was not intended to study the morphology of O. gutturosa in d etail; in order to confirm identification, however, male worms and pieces of femal e worms, up to 40 em long, were removed from infected nuchal ligaments and examined while fresh using a dissecting microscope. Also, the general morphology of microfila riae was noted before estimating microfilarial skin d ensities, in order to exclude other filarial larvae. For this purpose, sufficient numbers of Microfilaria gutturosa were obtained from the uterus of worms and from the skins of parasitized cattle; these were examined by a light microscope either as fresh preparations or after staining with Leishman's stain or brilliant cresyl blue. Microfilariae ex utero were collected by placing teased parts of gravid female parasites in petri dishes containing physiological saline for periods of from 30 min to I h, followed by removal of the females' r emnants, centrifugation of saline, and examination of the sediments. "Skin" microfilariae, on the other hand, were collected after incubating finely sliced pieces of skin in physiological saline for several hours, centrifugation, and sedimentation. Both the adult worms and the microfilariae were found to conform in morphology with the accepted description of the species. The relative d ensities of microfilariae in different parts of the skin were subsequently determined. Since the objective was primarily to form an opinion on distribution patterns of these larvae, only a crude m ethod of counting was pursued. From each of 33 male and female cattle with known infection, measured areas, approximately I cm 2, were taken from the skin of the ear, tail, umbilicus and udder or scrotum. These areas were comparable in thickn ess, and were cut into smaller portions and incubated overnight in plastic containers with an appropriate quantity of physiological saline. The number of microfilariae in the whole quantity of saline was then counted, and several washes made to include any r emaining larvae. A study of the gross and the histopathological lesions in the infected animals was also made. Microscopical sections were prepared after processing in paraffin, and were stained with Haematoxylin and eosin, Gomori's reticulin stain and periodic-acid Schiff reagent. RE SU LT S
Parasitological findings Table I summarizes the results of the survey carried out to d etermine the incidence of onchocerciasis in Sudanese cattle. The overall incidence of O. gutturosa in male and female animals was found to be approximately 68'5 per cent. The worms were located exclusively in the connective tissue of the nuchal liga ment, and none was found in the rumeno-splenic ligament or elsewh ere,
BRITISH VETERINARY JOURNAL,
131,
1
T AB LE 1 INCIDENCE
OF
Onchocerca gutturosa
AND
O. arm illata
ADULTS
IN
SUDANESE
CATTLE
Number irifected
Males Females Total
Number examined
0. gutturosa
0. armillata
180 68 248
121 (67 .2%) 49 (72. 1 %) 170 (68·5%)
138 (76.7%) 61 (89·7%) 199 (80 ·2%)
Note: Percentage incidence is given between brackets.
despite a careful search. Similarly, the aortic parasite, O. armillata, was extremely common; it occurred in more than 80 per cent of the animals seen, including all of those infected with O. gutturosa. O. armillata was found in nodules and tunnels within the aortic wall, particularly at the region of the aortic arch; like O. gutturosa, its incidence was higher in female cattle. In both cases, there was apparently no seasonal variation in incidence of the parasites, and most of the non-infected animals were relatively young in age. In the skin, two types of microfilariae were encountered. One type, which was only rarely observed, was sheathed and had well-developed striations and other morphological features consistent with those of Setaria spp. It appeared that these microfilariae were released from broken blood vessels when the skin was cut. On subsequent examination of some animals, a low incidence of S. labiatopapillosa adults was noted in the peritoneal cavity. However, the parasite was not systemically searched for and was therefore excluded from this survey. The other type of micro filariae, which was far more predominant, was identified as that of O. gutturosa, and accordingly counted. It occurred in all parts of the skin examined, with the highest densities in the skin of the ear, followed by the scrotum (or udder), the tail and least in the umbilicus (Table II ) .
Pathological findings Nuchal ligament. The connective tissue of affected ligaments was reddish or pinkish, oedematous and sometimes haemorrhagic, showing irregular, roughened areas and engorged superficial venules, particularly on the inner surface where the worms were located. The parasites were almost invariably confined to the funicular part of the ligament, being either concealed in the connective tissue, or, less commonly, forming hard, raised nodules resembling lymph nodes. These nodules revealed a greyish core of necrotic tissue in which portions of the worms were found embedded. Sometimes, the parasites appeared thicker than normal as a result of surrounding tissue reaction. Calcified worms were also commonly encountered, and were easily recognized by virtue of their whitish calcareous appearance (Fig. I). In histopathological preparations, cross-sections of female worms were often seen in the connective tissue (Fig. 2). They were sometimes intact, showing no evidence of degeneration, and many of them revealed parts of their uteri filled with large numbers or microfi lariae and embryonated eggs. As a result
a
~
:J:: a
~ ~
Q
TABLE II
Onchocerca gutturosa
(Mean counts of microfilariae per
I
22 12
Sex
Ear
Umbilicus
M
38"6 ± 18"6 (7"9-7 6 "5) 26"4 ± 10"9 (7" 1-44 "2)
1"4 2"6 (0"0- 5"8) 2"3 ± 2"2
F
Note : ranges are given between brackets"
±
(O"O- H)
~
( ± S"D" )
Scrotum
Tail
±
3 "2 ± 4"1 (0"0- 17"8) 4"0 ± 2"9 (0 "5- 1 7"3 )
11 "5
c::: ...., ....,
cm2 of skin)
Mean cOllcentration of microfilariae Number of animals
G
INFECTION IN SUDANESE CATTLE
11"1
(0"2- 37"6)
Udder
a f;:: ::;'
6"9 ± 4"7 (0"4- 33"6)
en
c:::
~
>Z
t>1 en t>1
o
~
>-l t"" t>1
-..t
<.0
80
BRITISH VETERINARY JOURNAL,
131, I
Fig. I. Showing calcified parts of O. gutturosa adults in the connective tissue of nuchal ligament.
of fixation, the parasites were shrunken and appeared surrounded each by an empty crescentric space lined by a hyaline wall. It was obvious, however, that the worms occupied tortuous, intercommunicating tunnels, often surrounded by histiocytes, lymphocytes and eosinophils, and supported by a delicate reticulum of fibrous connective tissue (Fig. 3). Sometimes, multinucleated giant cells were found in the vicinity of the parasites, and, at other times, following disintegration and absorption of the latter, a dense core of degenerated eosinophils was seen in the centre of well-developed lesions (Fig. 4). Also, eosinophils
Fig.
2.
Showing cross-sections of parasites in the connective tissue of nuchal ligament.
H. & E. x 60.
ONCHOCERCA GUTTUROSA IN SUDANESE CATTLE
81
Fig. 3. A g ra nulomatous resection with fibrosis around O. gutturosa in nuchal ligament.
H. & E.
X 1 20.
were sometimes found accumulating on the cuticle of the parasites. In some sections, an interesting finding was the occurrence of faintly acidophilic areas of fibrinoid change containing few, vacuolated histiocytes and remnants of microfilariae, around worms (Fig. 5). In still other cases, only calcified parasites were foun d which were, nonetheless, surrounded by m arked tissue reaction . This reaction seemed to have been present even before mineralization of the parasites, a nd the lesions therefore exhibited calcified centres with surrounding often heavy, accumulation of inflammatory cells. Occasionally, such lesions lay adjacent to each other, giving a characteristic "follicular" appearance. Calcium deposits, topographically unrelated to worms, were also found in the
Fig. 4. Section showing intense, darkly-stained zone of degenerated eosinophils in the centre of granuloma in the connective tissue of nuchal ligament. H. & E. X 120.
BRITISH VETERINARY JOURNAL,
1 31, 1
Fig. 5. Section of connective tissue of nuchal ligament showing zone of fibrinoid reaction around parasite, beside accumulation of inflammatory cells. H. & E. X 120.
rest of the connective tissue, but the latter more often revealed a loose, oedematous and richly vascularized appearance, with some areas undergoing marked mucoid degeneration, and others showing an infiltration of histiocytes, eosinophils and large numbers of maturing fibroplasts. Similar infiltration was also seen around small blood vessles in the connective tissue. Within the substance of the ligament itself, however, neither worms nor PAS-positive material could be demonstrated, although a heavy accumulation of lymphocytes was occasionally seen, with cells being mainly found in the interstices between fibrou s bundles of the ligament.
Fig. 6. Skin showing patchy accumulation of inflammatory cells. H. & E.
X 120.
ONCHOCERCA GUTTUROSA IN SUDANESE CATTLE
Skin. Although pathological lesions that could be attributed to onchocerciasis were not seen on gross examination of the skin, microscopical sections often revealed an inflammatory reaction, associated with the presence of large numbers of microfilariae in the dermis (Fig. 6). The latter larvae were either found within the inflamed areas themselves or were free from local cellular reaction and lay intact, just below the germinal cell layer of the epidermis. Typically, however, there was patchy or widespread accumulation of round cells and eosinophils in the superficial dermal layer or more deeply and around hair [olicles and cutaneous blood vessels. DISCUSSION
It is difficult to make a true assessment of the significance of bovine onchocerciasis in the Sudan, owing to the limited observations recorded above, but there is no doubt that both O. gutturosa and O. armillata are common helminths of cattle in the country. As was pointed out by Eichler & Nelson (1971), however, there appears to be no definite clinical manifestations associated with the presence of adult stages of the former species in the nuchal ligament, despite the severity of the local tissue reaction. On the other hand, the possibility that th e microfilariae may account for severe lesions in the skin o[ infected cattle, as was found in some of the present cases, and previously recorded by others (Niimi & Kuono, 1954; Herin et al., 1955), indicates that a more thorough investigation of the problem should be undertaken. From a parasitological standpoint, it was interesting to note that O. gutturosa adults were confined to the connective tissue of the nuchal ligament. This degree of "site-specificity" was also observed by Clarkson (1964) in a study of O. gutturosa in East Africa, but Eichler & Nelson (1971) suggested that it may vary with different geographical strains of the parasite. In some countries, the worms are also found in the connective tissue between the spleen and the rumen of infected animals. On the other hand, some authors (Johnston, 192 I; Strong et al., 1937) regarded the latter form (i.e. the rumeno-splenic form) as a different species, for which the name O. linealis was retained, and others disagreed on account that no obvious dimorphism was seen (Caballaro, 1945). Recently, Eichler (1 973), studying the systematics of O. gutturosa in British animals, also suggested that difference in the morphology of nuchal and rumeno-splenic forms of the parasite were variable and inadequate to justify considering them as two distinct species. Yet, he proposed that the controversy could "only be resolved by an experiment to see whether or not microfilariae, whatever their origin, are equally capable of undergoing final development either in the neck or between the rumen and spleen of cattle" . The other species of Onchocerca mentioned in this report, O. armillata, was recorded in the Sudan by Malek (1958). Later, detailed investigations of its histopathological and histochemical aspects were carried out (Mostafa et al., 19 66 ; Cerny, Mostafa & Cerna, 1966). However, these authors made no mention of possible clinical effects the parasite might exert on the animals. In Indi a, Patnaik (1962) describ ed severe paralysis and ocular lesions, associated
BRITISH VETERINARY JOURNAL, 131, I
with aberpant localization of microfilariae in the spinal cord and eye respectively, in cattle heavily infected with this parasite. It is not unlikely that similar cases also exist in the Sudan without their real cause being demonstrated. REFERENCES BALMICHEV, N. P. (1966) . Veterinar~a, 43(2), 54 (in Russian) . CABALLERO, C. E. (1945). An Inst. Bioi. 16,367. CERNY, L., MOSTAFA, I. E. & CERNA, j. (1966) . Sudan Medical Journal, 4 (4), 187. CLARKSON, M. j. ( 1964). Ann. trop. Med. Parasit. 58, 153. EICHLER, D. A. & NELSON, G. S. (1971 ) . J. Helminth . X LV(2!3), 245. EICHLER, D . A. (1973) ' J. Helminth. XLVII( I), 89. GNEDINA, M. P. (1959) . Byuleten Nauchno-Teknicheskoi Informratsii Vsesoyuznugo I nstituta Gelminthologii im K. 1. Skryabina, NO.5, I I (in Russian). HERIN, V., THRIENPONT, D. & FAIN, A. (1955) . Annis. Soc. beige Med. trop. 35, 523. JOHNSTON, T. M. ( 192 1). Trans. R. Soc. S. Aust. 45, 231. MALEK, E. (1958). J. Parasit. 44 (4, Sect. 2), 30. MOSTAFA, I. E., EL HASSAN, A. M., CERNA, j. & CERNA, L. (1966). Sudan Med. J. 4, 147. NUMI, D. & KUONO, I. ( 1954), Bull. Fac. Agric. Kagoshima Univ. No. 3, 151 (in japanese; English summary, p .162). NELSON, G. S. ( 1966) . Helm. Abs. 35, 31 I. PATNAIK, B. (1962 ). J. Helminth. XXXVI(3), 313. STRONG, R. P., BECQ.UAERT, j. C. , SANGROUND, j. H. & MUNOZ, O . M. ( 1937). Onchocercosis With Special Riference to the Central American Form of the Disease, 234 pp. Harvard University Press. (Accepted for publication 2 I February 1974) Onchocerca gutturosa (Neuntann, 1910) infection chez Ie betail soudanais (Hussein et al.) ResUDle. On a decouvert Onchocerca gutturosa, jusqu'alors inconnu au Soudan, chez 170 des 248 animaux males et femelles examines au "Omdurman Central Abattoir". L e parasite ne se trouvait que dans Ie tissu connectif du ligament nucal, OU, d'habitude, il provoquait une reaction severe. On trouva les microfilaires, dans des concentrations variees, dans la peau de I'oreille, de la queue, de I'ombilic, du scrotum ou du pis. On rencontra parfois des lesions pathologiques dues aces larves dans la peau. Invariablement, I'infection etait compliquee par O. armillata . Infektion sudanesischer Rin der ntit Onchocerca gutturosa (NeUD1ann, 1910) (Hussein et al.) Zusantntenfassung. Onchocerca gutturosa friiher unbekannt im Sudan wurde bei 170 von 248 im Omdurman Zentralschlachthof untersuchten Ochsen und Kiihen gefunden. Das Vorkommen der Parasiten beschrankte sich auf das Bindegewebe des lig.nuchae, wo es meistens schwere Gewebereaktionen verursacthe. Mikrofilarien fanden sich in verschiedenen Konzentrationen in der Haut von Ohren, Schwanz, Nabe!, Scrotum und Euter. Zuweilen sah man auch pathologische Laesionen in d er Haut, infolge von spater sich entwickelnden Larven. In jedem Fall bestand eine Mischinfektion mit O. armillata. Infecciones debidas a Onchocerca gutturosa (NeUD1ann, 1910) en ganados sudaneses (Hussein et al.) ResUD1en. Se encontr6 Onchocerca gutturosa, previamente desconocida en el Sudan, en 170 de 248 toros y vacas examinados en el matadero central de Omdurman. EI paras ito se ha1l6 confinado en e! tejida conectivo del ligamento nucal, en que normal mente causa reacciones tisulares muy fuertes. Se encontraron sus microfilarias en distintas concentraciones en la piel de la oreja, cola, ombligo, escroto 0 ubre. A veces se encontraron en la piellesiones patol6gicas debidas a las larvas de estas ultimas. Invariablemente, la infecci6n estuvo unida a infecci6n por O. armillata.