Synonyms. Definition: Acute protozoan remittent fever, of rainy season or after, with destruction of red globules, anæmia, emaciation, dropsy, icterus and cutaneous or mucous eruption or discharge. Distribution: India, Burma, Cochin China, Persia, Phillipines, etc. Trypanosoma Evansi: a fusiform flagellate infusorian with undulating membrane, attacking the red globules: agency of flies as carriers, infection of dogs; of crows; feeding, licking; rats; open sores; stables; yards; pastures; pickets; stagnant water; manure or rubbish heaps; abattoirs. Lesions: anæmia; trypanosoma swarms during relapses; leucocytosis; œdemas; effusions; blood extravasations; splenic enlargement; emaciation; gastric and intestinal congestions; gastric ulcers; kidneys petechiated, swollen; brain effusion. Incubation, 2 to 8 days. Symptoms: local swelling, 2 to 4 inches by 4th day; decreases to 14th day; the general symptoms; hyperthermia 102° to 104° F., night highest; dulness; sluggishness; inappetence; icterus; cutaneous eruption; remission in 1 or 2 days; exacerbation after 3 to 10 days; catarrhs; petechiæ; stocked legs; pectoral swelling; encreasing anæmia and emaciation; ulcers on mucosa or skin; generative excitement; fœtid diarrhœa; urine profuse, bilious, albuminous or with casts; thirst; intestinal rumbling; debility; marasmus; hair erect; skin dry, rigid. Duration variable. Diagnosis: based on above, confirmed by finding blood parasites, constantly fatal in horses. Surra in camel, ox, buffalo, rabbits, rats, mice, dogs, cats, apes. Treatment: unpromising; mercurials, iodides, chromates, arsenates, terebinthinate, phenic acid, santonin. Dry, clean, airy stable, dry grain, tonics. Prevention: keep horse and mule from infecting locality; use oxen rather: stables, pickets, etc., apart from marshes, pools, manure and rubbish heaps; disinfectants, insecticides, seclude all surra-affected animals: smudges. Sanitary police.
Synonyms. Sar, Zahrbad, Gumzahrbad, Kushkzaharbad, Sokra, Sokhra, Tap, Tapdik (Punjab): Phitgya, Purana (Meerut): Berbag (Bombay): Tarai, Tebersa, Wabai-ki-bokhar, Pernicious Anæmia, Trypanosomosis, Relapsing Fever, etc.
Definition. An acute, relapsing, protozoan fever of equines, camels and elephants, inoculable on other animals, occurring during or after the rainy season, and characterized by hyperthermia which is liable to be intermittent, remittent or relapsing, anasarcous swellings, petechiæ of the mucosæ, icterus, cutaneous eruption, nasal, ophthalmic, vaginal and other mucous discharges, rapidly advancing anæmia, emaciation and debility, and above all, by the presence in the blood, at intervals from one to six days, of swarms of protozoa, analogous to those found in dourine or nagana.
Geographical Distribution. Surra has long been known to the English veterinarians in India, occurring during or just after the rainy season, and especially on the low flooded lands, along canals, rivers, lakes, etc., and later in Burma, Cochin China, the Persian Gulf, Persia. Lingard claims its existence in East Africa, North and South America, Australia and Southern Europe, but he has evidently confounded it with nagana and other affections. The discovery of the disease by Dr. Slee in 1901, among American, Australian and Chinese ponies in the Philippines is suggestive of a very wide diffusion of the infection in Southern Asia and adjacent islands, with which an American work on veterinary medicine must deal.
Cause. Parasite. Trypanosoma Evansi. The essential cause of the disease, Trypanosoma Evansi, discovered by Dr. Griffith Evans, Inspecting Veterinary Surgeon, British Army, in 1880, is a flagellate infusorian, pointed at one end, near which is a dark centrosome, and from this a flagellum running along the free border of the broad undulating membrane to the extreme opposite end of the parasite and extended beyond this as a waving lash. The length of the Trypanosoma Evansi is 20 to 50μ, (10 to 14μ, Smith and Kinyoun, Manila), its breadth 1 to 1.5μ. By reason of its large size and active motion it is easily detected in a film of fresh blood under ⅙th inch objective, and no less easily when dried and stained on a cover glass. It must be borne in mind that the mature parasite appears in the blood at intervals in swarms, so that examination at one time of day, or on a particular day, may fail to detect it, while examinations made earlier or later are successful. The general structure and successive stages of growth of the parasite appear to be the same as described for the Trypanosoma Equiperdum of Dourine, to which accordingly the reader may turn for description. The distinction from that parasite is to be found mainly in the pathogenesis. In this respect it should be noted that the parasites are strongly attracted by the red globules, upon which they fasten themselves by the blunt ends, shaking the cell in the most vigorous manner and even breaking pieces off and carrying them away. They are most strongly attracted by the concave part of the disc, and when there are rouleaux they will bore between the globules and even push them apart (Evans).
The appearance of the disease at the conclusion of the rainy season when the waters dry up and become foul, has led to the idea that the parasite lives in waters, but as this is also the time of the great swarming and activity of flies, and as the trypanosoma is found in the bodies of tabanidæ and hippoboscidæ that have bitten affected animals (Lingard), and as horses crowded together so that the fly with piercing apparatus still wet can pass from horse to horse (Evans), the opinion has grown that it is a compulsory parasite which is transmitted through the bites of insects. In 1880, Griffith Evans found that the native Hindoos attributed the disease to the bites of a very large brown fly which was active in July (probably a tabanus), in 1897, Pease identified the incriminated fly as the tabanus tropicus. Finally, Rodgers, in 1901, took flies that had been on surra horses, kept them 4 days or longer and found that their bites failed to produce surra; whereas those that were allowed to go directly from the sick to the healthy animal produced the disease in the latter. The direct experimental inoculation from horse to horse infallibly conveys the disease so that the flies are not needed to pass the parasite through an intermediate stage of its existence, but merely to carry it. It follows that no particular fly is the bearer but any insect may carry the infection from a bite or sore to inoculate it on a sore or by a bite on a fresh animal. Different observers have noticed the tendency to the infection of dogs and other animals that fed from rubbish heaps, or upon the carcasses of animals dead of surra, suggesting at once the intervention of the swarms of flies that congregate at such places. This is probably another example of the shrewd insight of the common mind, as in the case of the tick-borne Texas fever.
Lingard finds another bearer in the crow which sits on the backs of affected horses, pecking at the wounds, and passes at once to other healthy horses to peck their sores.
Experiments in feeding the infested blood to sound animals, have apparently succeeded, and the observation that dogs and cats suffer from eating the carcasses is in favor of this view. Horses that lick the infested sores, or the blood drawn by the flies may readily infect themselves, and especially if the mouth bears scratches caused by fibrous food, leech bites, or sores from bits, or if the pharynx or stomach has been wounded by bots or spiroptera.
The water and food are blamed by the natives in some quarters, but Pease’s observations on the Bombay tramway horses, which all perished though kept on boiled water and carefully picked fodder from sound regions, would suggest that this if a channel of infection at all, is not the main one.
The bowel excretions of rats harboring trypanosoma, when mixed experimentally with the food of the horse, have been charged with causing surra, but there are objections to the acceptance of this as a common cause. The alleged period of incubation in the horse in such cases was 40 days in place of the usual 7 or 8 days, when inoculated from a horse first affected in this experiment on a second the usual incubation of 7 or 8 days was shown, and though the horse fed on rat’s dung in the infected region of Bombay contracted the disease, the experiment failed when the same dung was fed in a high dry region unaffected by surra. The natural inference is that Bombay experimental horses contracted the affection in the usual way, probably through insects.