Vulvar flap morphology of Haemonchus contortus in naturally infected slaughtered goats in Northern area of Bangladesh

Abstract

Background: Haemonchus contortus is regarded as one of the most prevalent and highly pathogenic parasite of ruminants. Vulvar flap morphology of female Haemonchus worms is useful to understand the biology of this nematode. Traits of vulvar morphology are considered as markers of ecological adaptation. A study was carried out to determine the types of vulvar flap present in female Haemonchus worms in naturally infected slaughtered goats in Northern area of Bangladesh. Methods: Abomasa of 520 goats (260 from Rajshahi and 260 from Noagon District) collected from January, 2013 through December, 2013 from different slaughter houses of northern area of Rajshahi, Bangladesh. Female Haemonchus worms were collected under a dissecting microscope and then washed under tap water to remove adhered feed residues from their body. All Haemonchus worms from each animal were preserved in 70% ethanol inside individually labeled universal bottles, until they were examined for the types of their vulvar flap. The statistical package SPSS 19 for Windows was used for data analysis. Parameters such as major vulvar morphotypes of Haemonchus spp were compared by Chi-square test in both study areas. Results: The major vulvar morph types was knobbed like (46.1%) followed by linguiform (33.5%) and smooth (20.4%). Out of 260 adult female Haemonchus worms collected from goats of Rajshahi district, 43.0% linguiform, 21.1% smooth and 35.8% knobbed vulvar morphs were identified. In Noagon district, 23.8% linguiform, 19.6% smooth and 56.5% knobbed vulvar morphs were observed. Linguiform type vulvar morphs were predominant in Rajshahi whereas knobbed type in Noagon district. Statistically significant (P<0.001) fluctuation was observed among three major vulvar flap morph types in the study areas. Sub-linguiform B (LB) was most common (96.6%) compared to Sub-linguiform A (LA); 3.4% type vulvar flap. There were no Sub-linguiform C (LC) and Sub-linguiform D (LD) types vulvar flap of Haemonchus spp detected in the study area. Conclusions: The study showed polymorphism in vulvar morphology of female Haemonchus spp of goats in selected area of Bangladesh. The morphological characters of female Haemonchus spp can help in the identification of type of species that occurs in study area.