ETIOPATHOLOGICAL STUDIES ON SPIROCHETOSIS IN COMMERCIAL LAYER BIRDS
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Date
2012
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AAU, Anand
Abstract
The present study was carried to know the etio-pathology of spirochetosis from natural outbreaks occurred in five different flocks belonged to three different commercial layer farms in Anand district during the period of February to July 2011. Epidemiological information like flock strength, system of management, age of birds and mortality were recorded. Blood samples were collected from clinically ailing birds for haematological studies. The blood/impression smears prepared were stained with both field stain containing eosin and methylene blue as well as giemsa stain. A detailed necropsy examination was performed on dead birds from the affected flocks and gross lesions were recorded. Tissue samples like liver, spleen, heart, kidney, lung, intestine, proventriculus and ovaries were collected in 10% neutral buffered formalin solution for histopathological examination. The natural outbreaks of spirochetosis occurred in layer flocks reared in cage system of management and in between the age group ranging between 14 to 74 weeks. Majority of the outbreaks were recorded in laying flocks. Only one outbreak was recorded in a growing flock. Mortality between the flocks varied from 3.98 to 16.51 percent. The overall mortality was 10.87 percent. The mortality was observed over a period of 2 to 6 weeks. The clinical symptoms observed in affected flocks were pale and anemic skin and visible mucus membrane, loss of appetite, cyanosis of comb and wattles, sickness, ruffled feathers, fever, weakness, droopy huddled-up appearance and greenish diarrhoea. The larval and adult stage tick especially Arguspersicus was found in clinically ailing birds in all the five affected flocks. The haematological data like Hb, PCV, TEC, MCV, MCH and MCHC were found significantly decreased in affected flocks and morphological type of anaemia based on erythrocytic indices was normocytic normochromic anaemia. The hematological findings relating to leucocyte count (TLC, DLC and absolute leucocyte count) were suggestive of leukocytosis with heterophilia and monocytosis. The spirochete organisms could be detected in abundant numbers in buffy coat smears rather than in blood smears from the same affected bird. The organisms were observed with difficulty and seen in very less numbers in blood smears. The organisms could be detected either in less or abundant numbers fi-om the heart blood smears prepared from plasma clot rather than red blood clot from the same bird while organisms could not be detected in impression smears made from liver or spleen showing typical gross lesions of spirochetosis. The characteristic gross pathological lesions were appeared in the liver and spleen. The gross lesions appeared in the liver were enlargement, paleness, focal to diffuse coagulative necrosis and mild petechial haemorrhages on the surface. There was characteristic enlargement and mottled of spleen with diffuse grayish areas of necrosis. Kidneys were pale and swollen in majority of the affected birds. Some of the birds from affected flocks I and III showed gross lesions of mild to moderate fibrinous pericarditis. The characteristic histopathological lesions in liver were mild to severe congestion, focal to diffuse areas of haemorrhages and multifocal areas coagulative necrosis along with infiltrations of mononuclear leucocytes mainly lymphocytes and macrophages and presence of spirochete organisms in the blood vessels in majority of the cases. The lesions in the spleen were characterized by multifocal areas of lymphoid necrosis along with hyperplasia of macrophages and teeming number of spirochete organisms in the blood vessels of splenic parenchyma. Kidney revealed mild to moderate infiltration of mononuclear cells mainly lymphocytes in the intertubular space along with tubular degeneration in some of the birds belong to flocks I and IV. Some of the birds from affected flocks I and III showed fibrinous pericarditis i.e. infiltration of mononuclear cells along with fibrin deposition.
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VETERINARY PATHOLOGY, A STUDY