Tropical liver fluke-induced stress in experimentally infected and immunised buffaloes.
Disease-related stress associated with Fasciola gigantica infection was investigated in 16 male, yearling Murrah buffaloes. The animals were randomly assigned to one of four groups. Animals in groups 1 and 2 were vaccinated subcutaneously with 4.8 mg of excretory-secretory antigen (group 1) or 1300 μg infection-specific antigen (group 2), in three doses. Subsequently, all the animals in groups 1, 2 and 3 were infected orally with 800 viable F gigantica metacercariae (bubaline origin) on week 6 of the experiment. The animals in group 4 served as healthy controls. The clinical progress of the disease with respect to the adrenocortical response to infection was assessed periodically. The infected animals in group 3 developed characteristic signs of the disease and had the highest in situ fluke population (mean [se] 331.8 [19.5] ). One of the four animals in group 3 died on day 110 postinfection (PI). Animals that had been immunised before infection (groups 1 and 2) acquired adequate levels of immunity, were comparatively healthier and had significantly lower (P<0.05) fluke populations (mean [se] 194.3 [11.8] in group 1 and 164.5 [9.2] in group 2). Throughout the course of the disease, the group 3 animals had significantly higher cortisol levels than those in groups 1 and 2 (P<0.01) from week 4 PI onward. Although animals in the immunised groups (groups 1 and 2) had increased hormone levels, they were not significantly different from those in the control animals in group 4. Cortisol levels were higher during the early prepatency phase (weeks 1 to 6 PI) than during the late prepatency and/or patency phases of the disease. Cortisol levels in the healthy control animals in group 4 remained within the normal range.
Division of Parasitology, Indian Veterinary Research Institute, Izatnagar-243122, Uttar Pradesh, India.
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Edith
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Thilagar
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Godara
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Sharma
D000818:Animals; D000947:Antigens, Helminth / Q000008:administration & dosage / Q000276:immunology; D002020:Buffaloes / Q000097:blood / Q000276:immunology / Q000469:parasitology; D005210:Fasciola hepatica / Q000254:growth & development; D005211:Fascioliasis / Q000097:blood / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D006854:Hydrocortisone / Q000097:blood*; D008297:Male; D011897:Random Allocation; D013312:Stress, Physiological; D014611:Vaccination / Q000662:veterinary*
D000947:Antigens, Helminth; D006854:Hydrocortisone