Morphological identification of adult male Haemonchus species in goats from Thailand and Lao PDR.

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Haemonchus spp. or barber's pole worms are one of the most highly pathogenic nematodes of ruminants causing economic losses in livestock worldwide. The current study was a first attempt to identify Haemonchus spp. from goats in Thailand and Lao PDR. Utilizing the inexpensive tools of the discriminant function (DF) combined with synlophe patterns is fundamental for understanding their epidemiological aspects. In total, 255 randomly chosen adult male Haemonchus worms from goats in various areas in each country were identified individually. For both these countries, about 94% based on the DF values, and 99%, 98%, and 97% based on synlophe patterns in the region of the esophageal intestinal junction (EI), 4 mm from the anterior end, and at both these positions, respectively, were identified as H. contortus. Other identified specimens defined as H. placei and hybrids as well as unclassified species based on synlophe patterns were proved using polymerase chain reaction (PCR); this also included some randomly chosen H. contortus by DF and synlophe patterns. All those specimens were confirmed as H. contortus being strongly supported by some genetic evidences and UPGMA analysis. Thus, it was assumed that all specimens in the current study were H. contortus. The morphological differences of this predominant species (H. contortus) in goats between the two countries were: body length, gubernaculum length, and left spicule barb length, while almost all characters of male worms individually measured appeared to overlap, mostly in H. contortus and H. placei, which may lead to misclassification. Therefore, using the DF along with synlophe patterns can assist in increasing the accuracy of Haemonchus spp. identification from goats in some areas where funding is limited, particularly in Lao PDR. The present results revealed that synlophe patterns in the EI region seemed to be promising for the identification of Haemonchus spp., while molecular techniques are also required to address ambiguous identification with some specimens.