Impact of treatment of gastrointestinal nemathelminths on body weight of sheep and goats.

Gastrointestinal nemathelminths affect productive as well as reproductive performance of a wide range of ruminants. To assess the impact of anthelmintic treatment on gain in body weight (b. wt.) of sheep and goat, a study was conducted using two different flocks of sheep and goats each maintained in semi intensive system. Infected animals in both the flocks were divided into three groups each. Group I and II in each flock were treated with levamisole (@7.5 mg/kg b. wt. subcutaneously) and fenbendazole (@5 mg/kg b. wt. orally), respectively. Animals of group III were kept as untreated control. Individual b. wt. and faecal egg count were recorded up to 42nd day post treatment. Results showed 100 % reduction in faecal egg count of sheep on day 7 after treatment with levamisole and on day 10 after treatment with fenbendazole. In goats, the reduction in faecal egg count was 82.60 % after treatment with levamisole and 78.87 % after treatment with fenbendazole on day 14 post treatment. The study also revealed mean increase of 29.57 and 22.67 % in b. wt. of sheep treated with levamisole and fenbendazole respectively 42nd day post treatment whereas mean b. wt. of infected untreated control groups decreased by 7.14 %. Similarly, there was an increase of 10.71 and 14.47 % in mean b. wt. of goats 42nd day post treatment with levamisole and fenbendazole, respectively whereas mean b. wt. of untreated control group decreased by 15.38 %. More weight gain was recorded in sheep as compare to goats after treatment as compared to the untreated control group, which may be due to some drug resistance in goat and required clarification by further studies in these ecological zones of Udham Singh Nagar.

Detection of benzimidazole resistance in gastrointestinal nematodes of sheep and goats of sub-Himalyan region of northern India using different tests.

The present investigation was planned with the objective of studying the status of benzimidazole (BZ) resistance in gastrointestinal nematodes (GIN) of sheep and goats of different agro-climatic zones of sub-Himalyan region of northern India using in vivo faecal egg count reduction test (FECRT) and in vitro tests namely egg hatch assay (EHA) and larval development assay (LDA). Out of fourteen flocks, FECRT detected resistance in eight flocks (two sheep flocks and six goat flocks) with FECR% ranging from 54.95 to 90.86. Pre treatment coproculture contained predominantly Haemonchus contortus, followed by Trichostrongylus spp., Oesophagostomum and Strongyloides, while post treatment coproculture results showed that only H. contortus survived fenbendazole (FBZ) (in FECRT) or thiabendazole (TBZ) (in LDA) treatment except in three flocks of Tarai region {one sheep flock (Us1), and two goat flocks (Ug1 and Ug5)} where BZ resistant Trichostrongylus were also detected. The GIN of those eight farms which were found resistant by FECRT were also detected resistant by EHA. Arithmetic mean and range of ED50 value of susceptible group was found to be 0.059 µg/ml and 0.037-0.096 µg/ml, respectively, and the same for the resistant group were found to be 0.119 µg/ml and 0.101-0.147 µg/ml, respectively. With LDA, the arithmetic mean and range of LC50 value of susceptible group was found 0.0030 µg/ml and 0.001-0.005 µg/ml, respectively, and those of resistant group was found 0.0105 µg/ml and 0.009-0.012 µg/ml, respectively. The values of Spearman rank correlation coefficient indicated that negative correlation was found between FECR% and ED50 and between FECR% and LC50 while positive correlation existed between ED50 and LC50 value and the p-values indicated that these correlations were statistically highly significant. In the present study, FECRT and EHA gave comparable results with regard to detection of BZ resistance in GIN in sheep and goats. Although with LDA, the threshold LC50 value could not be established as for EHA but LDA indicated the presence of low level of resistance in GIN of both sheep and goats. For effective worm control, regular monitoring for anthelmintic resistance is important to know the status of anthelmintic efficacy in a particular agro-climatic zone. The baseline information thus generated will enable timely management of benzimidazoles resistance in GIN.

Prevalence of gastrointestinal helminth infections in rodents of Tarai region of Uttarakhand.

The present work was aimed to investigate helminth biodiversity among rodents in order to evaluate the threat for helminth transmission to humans since they act as a potential source of parasitic zoonoses. In this study, faeces of 43 black rats (Rattus rattus) and 35 house mice (Mus musculus) were collected from various habitats viz. domestic places and agricultural fields of different parts of tarai region of Uttarakhand. These faecal samples were examined for the presence of parasitic eggs, adult and segments of the worms. The study revealed that the rodents were infected with 5 genera of helminth parasites, i.e. Hymenolepis nana, Hymenolepis diminuta, Syphacia muris, Capillaria hepatica, Trichuris muris and other strongyle eggs (2 species of cestodes and 4 species of nematodes). Adult Syphacia muris and segments of Hymenolepis nana were also recovered from faecal droppings. Of the 43 samples of black rat, all (100 %) and of the 35 samples of mice 9 (25.71 %) were found positive for one or more than one species of parasitic infections. Greater infection of H. diminuta 19 (44.18 %) followed by H. nana 17 (39.53 %) was seen in rat whereas mice were mostly infected with H. nana. The diversity and prevalence of various parasites reported here within domestic habitats may suggest that these can pose a high risk of helminth transmission to human population and are thus of considerable public health importance.

Esterase profile of Rhipicephalus (Boophilus) microplus populations collected from Northern India exhibiting varied susceptibility to deltamethrin.

Rhipicephalus (Boophilus) microplus is an economically important ectoparasite of cattle. Chemical acaricides remain the most practical method for control of these pests. During past two decades there have been increasing reports of resistance development against synthetic pyrethroids in tick populations of this species throughout the world. A study was conducted to determine the level of susceptibility of R. (B.) microplus to deltamethrin collected from different geographical locations of northern India. LPT bioassay results revealed LC(50) values of deltamethrin ranging from 0.035 to 0.00037 % A.I. Esterase profile of the tick larval extracts using native PAGE, revealed 5 bands of esterase activity designated EST-5 to EST-1A. Inhibitory tests recognized EST-1, EST-2 and EST-3 as Acetylcholinesterases (AchEs), EST-4 and EST-5 as Carboxylesterases (CaEs). The band intensity varied between tick populations of various locations, being more intense in case of the resistant populations. An extra band of esterase activity (EST-1A) was obtained in larval extracts of ticks from 3 locations. This increased esterase activity may be involved in the resistance development in these tick populations. Acaricide resistance is a multi-factorial phenomenon, thus other causes of increased resistance like sodium channel mutation and reduced drug penetration (e.g. cuticle thickening) and behavioural changes (e.g. avoiding the pesticides) are to be tested in future in order to confirm the basic cause of the resistance development in these acaricide resistant tick populations.

Immune responses against recombinant tick antigen, Bm95, for the control of Rhipicephalus (Boophilus) microplus ticks in cattle.

Immune responses against Bm95 recombinant cattle tick antigen and its protective efficacy for control of Rhipicephalus (Boophilus) microplus ticks were determined in experimental crossbred cow calves. Anti-Bm95 antibody titers, as assessed by indirect ELISA, in immunized calves ranged from 196.1+/-13.7 on day 0 to 7979.9+/-312.5 on day 110 post-primary immunization. The rise in antibody titer was statistically significant (p<0.01) throughout the study period. Besides this, constantly higher lymphoproliferative response (LPR), as assessed by lymphocyte stimulation test, was observed from 10 days post-immunization, but a positive LPR of antigen stimulated cells in immunized animals was recorded only on day 50 and day 70 post-immunization. Following challenge of immunized calves with larvae of R. microplus, significant increase (p<0.01) in rejection percentage, mean number of damaged ticks, mean percentage of dead ticks, and decrease in engorgement weight were recorded in immunized animals. Also, there were significant differences (p<0.01) in preoviposition period, oviposition period, egg mass weight and percent hatchability between the immunized and control calves. The percent reduction in number of adult females in vaccinated calves, reduction in mean weight of egg masses, percent reduction in mean weight and reduction in fertility of engorged females collected from vaccinated calves were determined and the efficacy of Bm95 recombinant cattle tick antigen was 81.27%.

The epidemiology of fasciolosis in ruminants in different geo-climatic regions of north India.

Epidemiological studies were conducted on Fasciola giagntica infection in different geo-climatic zones (hills, tarai and plains) in six states of north India during January 2001 to December 2004. Prevalence rates of 10.79, 13.90, 2.78 and 2.35 percent were recorded in cattle, buffaloes, sheep and goats, respectively. Animals in the tarai had the highest prevalence of fasciolosis followed by those in the hills and plains, respectively. The prevalence of infection in cattle and buffaloes was highest during the winters (11.84% cattle, 15.57% buffaloes) followed by summers and rains, respectively. However, the seasonal trends in sheep and goats were the reverse, with the peak prevalence during the rains (4.60% sheep, 2.71% goats). Abattoir studies revealed a higher prevalence in buffaloes (31.14%) than in sheep and goats. Screening of Lymnaea auricularia snails revealed that 5.48% of the snails harboured larval stages of F. gigantica. Also, the snails in the tarai had a higher prevalence (7.28%) of infection compared to those in the plains (1.57%). The results of the present study may help to devise an effective control strategy against fasciolosis in north India.