Molecular identification of abomasal nematodes (Haemonchus spp. and Ostertagia ostertagi) in naturally infected calves

Abstract

Clear variation in the pathogenicity and epidemiology of gastrointestinal nematodes and sensitivity to anthelminthic drugs require precise epidemiological information for such worms. Our work is the first effort to detect the abomasal nematodes (Haemonchus spp, Ostertagia ostertagi) in calves in Mosul, Iraq through amplification of rDNA ITS1 and ITS 2 regions. Four hundred and eighty (480) faecal samples were collected from 35 private calf herds between October 2021 and April 2022. Ages, origins of the herds, size of the herds, and gender were recorded. Microscopic examination and larval culture were conducted. Specified primers were used for molecular identification. The study showed a 50.6% total prevalence of gastrointestinal nematodes in calves. Haemonchus spp. and Ostertagia ostertagi rates were 62.13%, and 60.9%, respectively. The percentages of L3 of Haemonchus spp. and Ostertagia spp. were 32% and 14% respectively. Polymerase chain reaction (PCR) showed reaction products of 321 bp, and 257 bp for studied parasites, respectively. In conclusion, classical laboratory tools may be unable to identify precisely the species and subsequently, minimise the comprehension of parasitic species that circulate in animal populations. Molecular detection is a rapid, highly sensitive, specific and cost-effective procedure that accurately identifies parasite species.