PATHOLOGICAL STUDIES ON NECROTIC ENTERITIS ASSOCIATED WITH CLOSTRIDIUM PERFRINGENS IN COMMERCIAL CHICKEN
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Date
2021-04
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
Necrotic enteritis is caused by infection with and toxin production by
Clostridium perfringens (type A and C), a gram positive, spore forming
anaerobe. Perusal of available literature revealed a very few reports on necrotic
enteritis in chicken in the area under study. Hence, the present study was
undertaken to know the occurrence of necrotic enteritis associated with
C. perfringens in commercial chicken in natural cases, to study the gross and
histopathological lesions, to carry out isolation and identification of
C. perfringens by conventional bacteriological techniques and confirmation by
PCR.
In the present study, a total of 180 commercial chicken were collected
from private poultry diagnostic centres showing lesions suggestive of necrotic
enteritis at necropsy. Based on the pathological, bacteriological and molecular
studies, the overall occurrence of necrotic enteritis associated with
C. perfringens was found to be 37.8% in commercial chicken that comprised of
26.7 % in broilers and 11.1% in layers. Among the C. perfringens positive birds,
concurrent infection with coccidia was noticed in 41.17% of birds.
The clinical signs commonly reported in the necrotic enteritis affected
birds were loss of appetite, bloody or whitish diarrhoea and sudden death. On bacteriological isolation and identification, a total of 68 isolates of
C. perfringens were obtained and were confirmed by PCR with primers targeting
the 16S rRNA of C. perfringens. Further, the isolates were also found positive
for the alpha toxin gene of C. perfringens by PCR.
At necropsy, the birds were found dehydrated and had foetid odour. The
lesions were limited to intestines particularly jejunum while duodenum and ileum
were affected in few cases. Extraintestinal lesions were seen only in liver in few
cases.
Grossly, jejunum showed ballooning with gas and blackish
discolouration. Whitish foci visible through serosa were seen in some cases. Cut
section revealed brownish, foul smelling fluid and necrotic debris along with
sloughing of mucosa. An adherent brownish / greyish white diphtheritic
membrane covered the mucosa. Histopathologically, in less severe cases,
jejunum showed coagulation necrosis at apices of villi with viable deeper layers
of mucosa. In more severe cases, the lumen contained mixture of erythrocytes,
fibrin and desquamated epithelial cells. Extensive necrosis of villus epithelium,
an adherent necrotic diphtheritic membrane over the mucosa and infiltration of
mononuclear cells were the other changes noticed. The common finding in all the
birds was presence of gram positive rod shaped bacteria along the tips of villi, on
exposed lamina propria and in necrotic areas. Sections of duodenum and ileum
showed mild coagulative necrosis. Hepatic lesions consisted of congestion and
multifocal, greyish white, coalescing foci scattered on the surface of liver
grossly. Coagulative necrosis, congestion and mononuclear cell infiltration were
seen microscopically.
In birds with concurrent coccidiosis, three species of Eimeria viz. E.
acervulina, E. necatrix and E. maxima were identified. The intestinal lesions
were more severe and consisted of ballooning and haemorrhages grossly.
Haemorrhages and necrosis were found on the mucosa. Lumen contained blood
clots and necrotic debris. Histopathologically, developmental stages of coccidia
and extensive haemorrhages were seen in the lumen and in the mucosa, along
with rod shaped bacteria in the surrounding necrotising debris.
The present study revealed an overall occurrence of 37.8% of necrotic
enteritis associated with C. perfringens in commercial chicken in the area under
study indicating the impact of necrotic enteritis on poultry production leading to
economic losses.
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