Epidemiology of Haemonchosis in Goats Under Different Management Practices in Bangladesh

Abstract

The present study was designed to evaluate the prevalence of haemonchosis of goats at greater Rajshahi (Rajshahi and Noagon district), and was conducted at the parasitological laboratory in the Department of Animal Husbandry and Veterinary Science, University of Rajshahi, Bangladesh for the epidemiological and morphological studies of Haemonchus spp during the period from March, 2011 to December 2013. In this cross-sectional study, a total 720 goats were randomly selected from the villages, farms, pastures, veterinary hospitals, abattoirs and examined for Haemonchus infection. The aim of this study was to determine the occurrence of haemonchosis in relation to host factors like age, sex, breed, body condition as well as management factors like husbandry system, de-worming status, housing system, feeding system and herd-size of the goats, environmental factors like month, season and other factors like study area, examination procedure and vulvar morphology of adult female Haemonchus spp. A total of 720 goats examined, of which 416 goats were found positive for Haemonchus spp infection and the overall prevalence of haemonchosis in goat was 57.8%. The prevalence was compared with age, sex, breed, and body condition of the goats. There was statistically significant (P<0.001) difference observed among the risk factors of age, sex and body condition of goat. However, there was no significant difference (P>0.05) observed in breed of goats. In the present study, the prevalence of haemonchosis was also compared with husbandry system, floor of housing, de-worming status, feeding system and herd-size of goats. All the management factors were observed statistically significant (P<0.001) difference in the epidemiology of haemonchosis in goats of the study area. During this study, the highest prevalence was observed in the month of July (82.1 %) followed by August (79.7 %) and lowest in the January (28.3 %) followed by February (38.7 %). Among the season, the peak level of Haemonchus infection was recorded in rainy (76.6%) season followed by summer (56.0%) and lowest in winter (40.5%) season. The prevalence among different month and season when compared statistically (Chi-square test and ANOVA) was revealed significant differences (P<0.001). Prevalence of haemonchosis did not vary significantly (P>0.05) between the study sites. The prevalence of haemonchosis was higher in necropsy (65.5%) compared to coproscopy (50.1%) findings and statistically (P<0.01) influenced by the examination procedure of the present study. It was also noted that light infection (48.4%) were higher followed by moderate (41.2%) compared to (10.4%) heavy infection of the affected goats. In necropsy, moderate infection was higher (54.2%) than light (28.6%) degree infection followed by heavy (17.0%) degree of infection was identified by counting of adult Haemonchus spp in the abomasum of slaughtered goats. In both examination procedure, chi-square test result was highly significant (P<0.001) difference among the degree of infection of affected goats.

From the collected stomach worms, the percentage of female were 63.0% significantly (P<0.001) higher than adult male (37%) Haemonchus spp. The result also revealed that sex ratio of adult Haemonchus spp were found 1:0.59. The knobbed type of vulvar flap was the predominant (46.1%) type of Haemonchus spp compared to other morphs. In the statistical analysis, significant (P<0.001) fluctuation was observed among three major vulvar flap morph types in both of the study area. Among the linguiform subtypes, linguiform-B (LB) was the higher (96.6%) compared to linguiform-A (LA) but there was no found in LC, LD, LI linguiform subtypes of Haemonchus spp in the study area. The present work showed the widespread occurrence of polymorphism in vulvar morphology of female Haemonchus spp of goats in the study area of Bangladesh. The present study suggests that young aged group, female, poor body conditioned goats and management practices like husbandry system, floor of housing, de-worming status, feeding system and herd-size of goats were more susceptible to haemonchosis in the study area but cross-bred goats was least susceptible to haemonchosis and requires special attention for its control. Therefore, the epidemiological evidence of the present investigation showed that haemonchosis is considerably prevalent disease of goats in the study area. Hence, strategic control method and good management practices are recommended. Prevalence, epidemiology, morphological, molecular and genetic characterization of Haemonchus spp with biology and significance of different vulvar flap types, subtypes and identification of Haemonchus in all species in different agro-ecologies, animal species and breeds on management system in other districts of Bangladesh and other countries will need to be pursued.