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Tularemia: Diagnosis and Treatment
Medical Clinics of North America May, 1937. Mayo Clinic Number
TULAREMIA: DIAGNOSIS AND TREATMENT
THOMAS B. MAGATH ALTHOUGH tularemia has been studied as such but little more than a decade, more is known about the causative organism, its transmission, the lesions it produces, the symptoms it causes, and about the prophylaxis, treatment, and incidence of the disease, than practically any other infection. When the disease was known only in the western states, the difficulties of diagnosis were restricted; but now that it has been reported from every region of the United States, many parts of Canada, and from other continents as well, geographic factors no longer serve to prod the clinician's threshold of suspicion; he may encounter the disease in a patient from any locality. DIAGNOSIS
The occupation of the patient is important. If he is one who by the nature of his work must handle wild game, or ride the western or middle-western prairies or farm land, he is more liable to contract tularemia than otherwise; and if he is a hunter who bags and skins his own game, he is also liable to infection. Men are much more often infected than women, but women who clean and cook rabbits and certain other game are also liable to become infected. Of fundamental importance in the diagnosis of tularemia is the history of contact with one of the susceptible mammals, birds, insects or ticks. While it is by no means certain that all the transmitting agents have been discovered, it is known that the disease is naturally present in the wild rabbit, grouse, coyote, cat, fox, muskrat, squirrel, woodchuck, range sheep, meadow mouse, rats and horned owl. Wilbur and Leser recently reported a case contracted from handling a ringneck pheasant. Insects known to transmit tularemia are the deer 855
THOMAS B. MAGATH
fly (Chrysops discalis), the wood ticks (Dermacentor andersoni, Dermacentor variabilis, and Dermacentor occidentalis) , the rabbit tick (H (Emaphysalis leporispalustris) , and the grouse tick (H (Emaphysalis cinnabarina). Failing to elicit the history of contact with one of these mammals or birds, as by handling, dressing, cooking, or caring for their pelts or skins, or of being bitten! by one of these insects or ticks or by contact with the body juices of such insects, as by slapping the insect and spattering its contents into the eye, one must inquire into the possibility of the patient's having handled cultures of the organism or experimented with animals inoculated with Pasteurella tularensis. The history of contact with a valid source of infection is so important that the possibility must be thoroughly explored and, failing to obtain a positive history, the probability of tularemia must be only remotely considered. The Lesions.-The time of the appearance of the local lesion after exposure is significant and, as a rule, is from one to four days, rarely as long as twelve days. A limited group of cases have been reported in which no local lesion occurred and these, for the most part, have been among laboratory workers. Although, experimentally, the organism can be made to invade the body through the unabraided skin, it has been suggested that the so-called typhoidal type of tularemia occurs as a result of accidental ingestion or insufflation of the organism. Occasionally one may swallow a tick and, if infected, it might conceivably cause the disease. The location of the lesion is most frequently on the hands or arms, but lesions of the eye are by no means uncommon. If the disease is acquired from ticks, the location of the initial lesion might be any place on the body, but it is most often on the lower extremities. The lesion begins as a papule,- and by necrosis an ulcer forms during the second week. Such ulcers are of the punchedout type with diffuse necrosis, polymorphonuclear cell infiltration and nuclear fragmentation; the ulcers break down early and drain. There is an early (often in forty-eight hours) lymphangitis and lymphadenitis, affecting the regional lymph 1 Some have suggested the bacteria are transmitted by the feces of the tick a~d not by its bite.
TULAREMIA: DIAGNOSIS AND TREATMENT
857
nodes. These are tender and painful and usually proceed rapidly to suppuration. The general symptoms, which begin abruptly, are like those of any other severe infection. The fever curve shows an abrupt rise, often to 103° or 104° F., and remains at a high level with but slight fluctuations. There are often distinct periods of remission followed by recurrence of the fever. After two weeks or a month of such bouts the fever usually subsides, but the symptoms of fatigue and even prostration continue for some time, even for a year. Not uncommonly one observes physical and subjective signs of bronchitis, bronchopneumonia or even pleural effusion, and indeed these may be very prominent. In certain cases in which no local lesion is found the whole course may be one of bronchopneumonia. In some cases without local lesions the disease simulates typhoid fever, and in any particular case leukocytosis, enlargement of the spleen and skin lesions, such as macules, papules, vesicles and pustules, may occur. LABORATORY FINDINGS
The laboratory investigation of tularemia is of paramount importance. If the patient is observed during the first two weeks of the infection, one may be successful in isolating the organisms from the lesion either by culturing on cystine agar, as recommended by Frances, or by modification of this medium, as proposed by Rhamy and by Foshay. The organism may also be isolated from a draining lymph node or from the blood stream. One is more likely to succeed if a guinea-pig is first inoculated with the material to be tested. Within five or six days the animal will show the typical lesions, from which Pasteurella tularensis can be readily obtained if the organism is present in the material. Pasteurella tularensis is a gramnegative, nonmotile, pleomorphic bacillus, growing scantily as a rule. It ferments glucose and glycerol, and most strains ferment mannose, levulose and maltose. In the presence of these sugars, acid is first produced, then alkali. Hydrogen sulfide is produced by its action on cystine. Skin Test.-A skin test developed by Foshay is reported to be very useful and reliable in the early diagnosis of the disease, in fact, as early as the third day after infection. The
THOMAS B. MAGATH
antigen is prepared by killing and treating a suspension of bacteria with 1 per cent formaldehyde for twenty-four hours, then treating it with hydrogen peroxide for forty-eight hours, followed by 1 per cent sodium ricinoleate in distilled water for twenty-four hours. The preparation may be made by treating organisms with nitrous acid for twenty-four hours, then suspending them in 1 per cent sodium ricinoleate and treating with 0.5 per cent phenol. If the disease is of recent origin, a test is made by injecting a small amount of antigen intracutaneously, enough to make a wheal 2 mm. in diameter; if the disease has been present for some time, enough antigen is injected to make a wheal 4 mm. in diameter. When read at forty-eight hours, a positive reaction has an erythematous wheal 5 to 6 cm. in diameter, with a hard indurated center about 1 cm. in diameter. The reaction lasts five days and a brown patch remains for several weeks. The test will be positive at least as long as five years after infection; it must be interpreted, therefore, in light of the patient's symptoms. Agglutination Test.--After the patient has suffered from the disease about two weeks, the blood serum exhibits both a positive complement-fixation reaction and a positive agglutination test. The complement-fixation test is performed along standard lines using as antigen a suitable suspension of the organism. The test is of scientific interest, but on account of its complexity it is not recommended for routine use. Of greater practicality, the agglutination test is to be preferred. A suitable, killed suspension of the organism is treated with varying dilutions of the patient's serum and the reading is made after incubation. At first the titer is low, 1 :40 to 1 :80, but it rises rapidly and, by the third week, it is usually quite high, even as high as 1: 5,000. The reaction persists for months or even years. A rising titer is perhaps the -most perfect corroborating test, next to actual isolation of the organism from the lesion, a very much more difficult task. In cases without a local lesion or exact history of exposure, especially when the chief findings are in the chest, a rising titer in the agglutination test may be the chief basis for establishing a diagnosis. If one must make the diagnosis at necropsy, it must rest on the fi'nding of typical lesions in the lung, liver and spleen,
TULAREMIA: DIAGNOSIS AND TREATMENT
859
miliary necrotic areas, essentially caseous. The lesions in the lungs are characterized by thrombosis of small arterioles' with necrosis, and surrounding mononuclear cell infiltration. One may isolate the organism from the lesions; or better, inoculate a guinea-pig with the material. It may be possible to obtain enough serum with which to perform an agglutination test. TREATMENT
Prophylaxis.-One may fairly successfully avoid the disease by handling no susceptible animals and by avoiding ticks and deer flys. In dressing game, rubber gloves should be worn, and sick wild rabbits, squirrels and mice should be avoided. Certainly after handling any of these animals the hands should be carefully scrubbed with soap and water and washed in an antiseptic solution. If one has received scratches or wounds while handling susceptible animals, the wound should be treated by thorough washing and application of a good antiseptic. Foshay has advocated immunizing laboratory workers and those engaged in the wild rabbit industry with a detoxified vaccine he has developed, but as yet no extensive use of it has been reported. Active Treatment.-Aside from general supportive measures and surgical drainage of liquefied lymph nodes, there is no particular remedy to advise except certain specific procedures. In a limited number of cases, two having been reported by Baer, the local lesion has been treated with roentgen rays. Both of Baer's patients were treated before the fourth day; one had lymphadenitis but the other did not, and a positive agglutination test developed in both cases, although at first i,t was negative. The patients were treated with one-half unit ( erythema) of unfiltered roentgen rays applied to the lesion and both showed marked improvement the next day. The disease was apparently aborted. After the disease has advanced, various forms of treatment have been suggested. Fisher reported treating three patients with neoarsphenamine, although the first case was diagnosed on the basis of the history and clinical manifestations only. Three doses, 0.45 gm., 0.6 gm., and 0.75 gm., were given at five-day intervals. He reported that all the patients were well
860
THOMAS B. MAGATH
after the third dose. Some isolated instances of beneficial resuIts following the use of certain dyes have been reported, but these reports and the lack of confirmation leave one doubtful as to the value of such remedies. Foshay's Serum.-The greatest progress in treatment has been made by Foshay. He has immunized goats and horses over long periods of time with detoxified antigens of Pasteurella tularensis. The serum is obtained and administered intravenously, usually in two doses of 15 c.c. each on successive days. In cases in which the lymph nodes are greatly involved, a third dose is indicated. It should be given as early as possible and with the usual precautions against reactions. Improvement is usually noted on the third day. He has reported on 240 cases treated with striking effects. The duration of fever was not shortened, being 26.44 days on the average. The d4ration of adenopathy was lessened by nearly half, or to 2.41 months. The duration of the disease and the disability due to it was shortened to 2.78 months, or about half the time of untreated cases, and the freedom from subjective symptoms was effected almost immediately. The mortality was reduced to about a third the usual mortality of 6 to 8 per cent. The best and most striking results are obtained when patients are treated during the first three weeks and, after eight weeks, it is questionable whether the risk of serum treatment and the uncertain benefit to be gained justify its use. Sharp and Dohme have placed on the market a serum made after the manner of Foshay, and Flinn reported favorably on its use in two cases. One patient was given 30 c.c., the other 90 c.c., followed by 30 C.c. of Foshay's immune goat serum. Since these are the only reports available, one must reserve opinion on the commercial product until more cases are reported. It would be advisable to develop some means of concentrating the serum, ~s has been done with better known immune serums. It can be seen that specific treatment of tularemia is still somewhat in an experimental· stage, but the brilliant results which have attended work on this interesting infection foreshadow a solution to the problem of treatment in the not too distant future.
TULAREMIA: DIAGNOSIS AND TREATMENT
THOMAS B. MAGATH ALTHOUGH tularemia has been studied as such but little more than a decade, more is known about the causative organism, its transmission, the lesions it produces, the symptoms it causes, and about the prophylaxis, treatment, and incidence of the disease, than practically any other infection. When the disease was known only in the western states, the difficulties of diagnosis were restricted; but now that it has been reported from every region of the United States, many parts of Canada, and from other continents as well, geographic factors no longer serve to prod the clinician's threshold of suspicion; he may encounter the disease in a patient from any locality. DIAGNOSIS
The occupation of the patient is important. If he is one who by the nature of his work must handle wild game, or ride the western or middle-western prairies or farm land, he is more liable to contract tularemia than otherwise; and if he is a hunter who bags and skins his own game, he is also liable to infection. Men are much more often infected than women, but women who clean and cook rabbits and certain other game are also liable to become infected. Of fundamental importance in the diagnosis of tularemia is the history of contact with one of the susceptible mammals, birds, insects or ticks. While it is by no means certain that all the transmitting agents have been discovered, it is known that the disease is naturally present in the wild rabbit, grouse, coyote, cat, fox, muskrat, squirrel, woodchuck, range sheep, meadow mouse, rats and horned owl. Wilbur and Leser recently reported a case contracted from handling a ringneck pheasant. Insects known to transmit tularemia are the deer 855
THOMAS B. MAGATH
fly (Chrysops discalis), the wood ticks (Dermacentor andersoni, Dermacentor variabilis, and Dermacentor occidentalis) , the rabbit tick (H (Emaphysalis leporispalustris) , and the grouse tick (H (Emaphysalis cinnabarina). Failing to elicit the history of contact with one of these mammals or birds, as by handling, dressing, cooking, or caring for their pelts or skins, or of being bitten! by one of these insects or ticks or by contact with the body juices of such insects, as by slapping the insect and spattering its contents into the eye, one must inquire into the possibility of the patient's having handled cultures of the organism or experimented with animals inoculated with Pasteurella tularensis. The history of contact with a valid source of infection is so important that the possibility must be thoroughly explored and, failing to obtain a positive history, the probability of tularemia must be only remotely considered. The Lesions.-The time of the appearance of the local lesion after exposure is significant and, as a rule, is from one to four days, rarely as long as twelve days. A limited group of cases have been reported in which no local lesion occurred and these, for the most part, have been among laboratory workers. Although, experimentally, the organism can be made to invade the body through the unabraided skin, it has been suggested that the so-called typhoidal type of tularemia occurs as a result of accidental ingestion or insufflation of the organism. Occasionally one may swallow a tick and, if infected, it might conceivably cause the disease. The location of the lesion is most frequently on the hands or arms, but lesions of the eye are by no means uncommon. If the disease is acquired from ticks, the location of the initial lesion might be any place on the body, but it is most often on the lower extremities. The lesion begins as a papule,- and by necrosis an ulcer forms during the second week. Such ulcers are of the punchedout type with diffuse necrosis, polymorphonuclear cell infiltration and nuclear fragmentation; the ulcers break down early and drain. There is an early (often in forty-eight hours) lymphangitis and lymphadenitis, affecting the regional lymph 1 Some have suggested the bacteria are transmitted by the feces of the tick a~d not by its bite.
TULAREMIA: DIAGNOSIS AND TREATMENT
857
nodes. These are tender and painful and usually proceed rapidly to suppuration. The general symptoms, which begin abruptly, are like those of any other severe infection. The fever curve shows an abrupt rise, often to 103° or 104° F., and remains at a high level with but slight fluctuations. There are often distinct periods of remission followed by recurrence of the fever. After two weeks or a month of such bouts the fever usually subsides, but the symptoms of fatigue and even prostration continue for some time, even for a year. Not uncommonly one observes physical and subjective signs of bronchitis, bronchopneumonia or even pleural effusion, and indeed these may be very prominent. In certain cases in which no local lesion is found the whole course may be one of bronchopneumonia. In some cases without local lesions the disease simulates typhoid fever, and in any particular case leukocytosis, enlargement of the spleen and skin lesions, such as macules, papules, vesicles and pustules, may occur. LABORATORY FINDINGS
The laboratory investigation of tularemia is of paramount importance. If the patient is observed during the first two weeks of the infection, one may be successful in isolating the organisms from the lesion either by culturing on cystine agar, as recommended by Frances, or by modification of this medium, as proposed by Rhamy and by Foshay. The organism may also be isolated from a draining lymph node or from the blood stream. One is more likely to succeed if a guinea-pig is first inoculated with the material to be tested. Within five or six days the animal will show the typical lesions, from which Pasteurella tularensis can be readily obtained if the organism is present in the material. Pasteurella tularensis is a gramnegative, nonmotile, pleomorphic bacillus, growing scantily as a rule. It ferments glucose and glycerol, and most strains ferment mannose, levulose and maltose. In the presence of these sugars, acid is first produced, then alkali. Hydrogen sulfide is produced by its action on cystine. Skin Test.-A skin test developed by Foshay is reported to be very useful and reliable in the early diagnosis of the disease, in fact, as early as the third day after infection. The
THOMAS B. MAGATH
antigen is prepared by killing and treating a suspension of bacteria with 1 per cent formaldehyde for twenty-four hours, then treating it with hydrogen peroxide for forty-eight hours, followed by 1 per cent sodium ricinoleate in distilled water for twenty-four hours. The preparation may be made by treating organisms with nitrous acid for twenty-four hours, then suspending them in 1 per cent sodium ricinoleate and treating with 0.5 per cent phenol. If the disease is of recent origin, a test is made by injecting a small amount of antigen intracutaneously, enough to make a wheal 2 mm. in diameter; if the disease has been present for some time, enough antigen is injected to make a wheal 4 mm. in diameter. When read at forty-eight hours, a positive reaction has an erythematous wheal 5 to 6 cm. in diameter, with a hard indurated center about 1 cm. in diameter. The reaction lasts five days and a brown patch remains for several weeks. The test will be positive at least as long as five years after infection; it must be interpreted, therefore, in light of the patient's symptoms. Agglutination Test.--After the patient has suffered from the disease about two weeks, the blood serum exhibits both a positive complement-fixation reaction and a positive agglutination test. The complement-fixation test is performed along standard lines using as antigen a suitable suspension of the organism. The test is of scientific interest, but on account of its complexity it is not recommended for routine use. Of greater practicality, the agglutination test is to be preferred. A suitable, killed suspension of the organism is treated with varying dilutions of the patient's serum and the reading is made after incubation. At first the titer is low, 1 :40 to 1 :80, but it rises rapidly and, by the third week, it is usually quite high, even as high as 1: 5,000. The reaction persists for months or even years. A rising titer is perhaps the -most perfect corroborating test, next to actual isolation of the organism from the lesion, a very much more difficult task. In cases without a local lesion or exact history of exposure, especially when the chief findings are in the chest, a rising titer in the agglutination test may be the chief basis for establishing a diagnosis. If one must make the diagnosis at necropsy, it must rest on the fi'nding of typical lesions in the lung, liver and spleen,
TULAREMIA: DIAGNOSIS AND TREATMENT
859
miliary necrotic areas, essentially caseous. The lesions in the lungs are characterized by thrombosis of small arterioles' with necrosis, and surrounding mononuclear cell infiltration. One may isolate the organism from the lesions; or better, inoculate a guinea-pig with the material. It may be possible to obtain enough serum with which to perform an agglutination test. TREATMENT
Prophylaxis.-One may fairly successfully avoid the disease by handling no susceptible animals and by avoiding ticks and deer flys. In dressing game, rubber gloves should be worn, and sick wild rabbits, squirrels and mice should be avoided. Certainly after handling any of these animals the hands should be carefully scrubbed with soap and water and washed in an antiseptic solution. If one has received scratches or wounds while handling susceptible animals, the wound should be treated by thorough washing and application of a good antiseptic. Foshay has advocated immunizing laboratory workers and those engaged in the wild rabbit industry with a detoxified vaccine he has developed, but as yet no extensive use of it has been reported. Active Treatment.-Aside from general supportive measures and surgical drainage of liquefied lymph nodes, there is no particular remedy to advise except certain specific procedures. In a limited number of cases, two having been reported by Baer, the local lesion has been treated with roentgen rays. Both of Baer's patients were treated before the fourth day; one had lymphadenitis but the other did not, and a positive agglutination test developed in both cases, although at first i,t was negative. The patients were treated with one-half unit ( erythema) of unfiltered roentgen rays applied to the lesion and both showed marked improvement the next day. The disease was apparently aborted. After the disease has advanced, various forms of treatment have been suggested. Fisher reported treating three patients with neoarsphenamine, although the first case was diagnosed on the basis of the history and clinical manifestations only. Three doses, 0.45 gm., 0.6 gm., and 0.75 gm., were given at five-day intervals. He reported that all the patients were well
860
THOMAS B. MAGATH
after the third dose. Some isolated instances of beneficial resuIts following the use of certain dyes have been reported, but these reports and the lack of confirmation leave one doubtful as to the value of such remedies. Foshay's Serum.-The greatest progress in treatment has been made by Foshay. He has immunized goats and horses over long periods of time with detoxified antigens of Pasteurella tularensis. The serum is obtained and administered intravenously, usually in two doses of 15 c.c. each on successive days. In cases in which the lymph nodes are greatly involved, a third dose is indicated. It should be given as early as possible and with the usual precautions against reactions. Improvement is usually noted on the third day. He has reported on 240 cases treated with striking effects. The duration of fever was not shortened, being 26.44 days on the average. The d4ration of adenopathy was lessened by nearly half, or to 2.41 months. The duration of the disease and the disability due to it was shortened to 2.78 months, or about half the time of untreated cases, and the freedom from subjective symptoms was effected almost immediately. The mortality was reduced to about a third the usual mortality of 6 to 8 per cent. The best and most striking results are obtained when patients are treated during the first three weeks and, after eight weeks, it is questionable whether the risk of serum treatment and the uncertain benefit to be gained justify its use. Sharp and Dohme have placed on the market a serum made after the manner of Foshay, and Flinn reported favorably on its use in two cases. One patient was given 30 c.c., the other 90 c.c., followed by 30 C.c. of Foshay's immune goat serum. Since these are the only reports available, one must reserve opinion on the commercial product until more cases are reported. It would be advisable to develop some means of concentrating the serum, ~s has been done with better known immune serums. It can be seen that specific treatment of tularemia is still somewhat in an experimental· stage, but the brilliant results which have attended work on this interesting infection foreshadow a solution to the problem of treatment in the not too distant future.