Molecular epidemiology of echinococcosis in northern India and its public health significance
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Date
2011
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GADVASU, Ludhiana
Abstract
The present study was undertaken keeping in view the importance of echinococcosis in India. Out of a total of 4130 animals examined, 66 were positive for hydatid cysts with overall prevalence rate of 1.59 per cent. The prevalence of hydatid cysts was highest in cattle (5.39%) followed by buffaloes (4.36%), pigs (3.09%), sheep (2.23%) and goat (0.41%). Irrespective of the species, the disease was found to be positively correlated with increase in age in cow (r = +0.98), buffalo (r = +0.83), sheep (r = +0.99), goat (r = + 0.99) and pigs (r = +1.0). The disease was found to be non significant in relation to the sex of the species viz. buffalo (p=0.88), pigs (p=0.97), sheep (p=0.90), goat (p=0.82) and cow (p=0.49). In buffalo, the disease was found to be non significantly high (p=0.26) in necropsied when compared with slaughtered animals. In pigs, the disease was non significantly high (p=0.30) in stray/wild/desi pigs than farm/crossbred pigs with the relative risk of 2.15 in stray/wild/desi pigs. The arrangement of hooks in rostella was alternate with large and small hooks in two rows in all the samples and the shape of the hooks was smooth in their outline. Strong positive correlations were found between LHTL, LHBL with NUH (0.24, 0.34) whereas very weak/no correlation was found between LHTL, LHBL with SHBL (0.0, 0.009). The results indicate that morphological analysis can be used as a valid criterion for differentiation of different strains of E. granulosus. All the tested 50 samples (10 from each species) of hydatid cysts were found positive using PCR. Nine samples were got sequenced in both the directions. Clear and readable sequences were obtained and phylogenetic analysis was performed (NCBI, Blast). In total, 7 (77.7%) isolates, from cattle (2), pigs (2), buffaloes (1) and goat (2) were clustered with the Indian Buffalo (G3) strain of E. granulosus, while 2 (22.2%) isolates from sheep were clustered with the sheep strain (G1) of E. granulosus. Histopathologically, there was slight hemorrhage, leucocyte infiltration and mild hepatocellular degeneration in the liver. The parenchyma around the cyst was hard due to fibrous capsule. Around the hydatid cyst there was marked cellular reaction characterized by proliferation of fibroblasts, infiltration of mononuclear cells and eosinophils. Out of a total of 212 dogs examined, 3 were positive for eggs of the Taeniidae family (Prevalence 1.41%). The prevalence of the eggs was highest in stray dogs (9.09%) having access to condemned meat/offalâ s (living near slaughter shops/post mortem areas) followed by stray dogs catched by Dogy Lane Veterinary Hospital from residential areas in Ludhiana (1.23%). None of the sample was found positive from 109 pet dogs visiting small animal clinic GADVASU. The disease was found to be significantly high (p=0.004) in stray dogs having access to condemned meat/offalâ s (living near slaughter shops/post mortem areas). None of the 3 samples were found positive using PCR indicating less than 0.47% prevalence of E. granulosus in this study. Out of total of 92 serum samples examined, 15 (16.30%) were positive for human hydatidosis. Among different occupational risk groups, non significantly high sero prevalence was recorded in dog handlers (30%), followed by dairy farmers/farm labour (26.66%), HIV positive subjects (25%), persons with liver disorders (14.81%), veterinary doctors (6.25%) and control group (6.25%). The results indicate emergence of human hydatidosis in north India. The sero prevalence was positively correlated with increase in age (r=+0.47) viz. highest in persons more than 60 years of age and no subject was found positive in persons less than 20 years old. The sero prevalence was found to be non significantly high viz. 18.03 per cent (11/61) in male subjects when compared with female subjects where low sero prevalence of 12.90 per cent (4/31) was recorded.