Phylogenetic analysis of Eimeria tenella isolated from the litter of different chicken farms in Mymensingh, Bangladesh.

BACKGROUND: Eimeria tenella is the most pathogenic intracellular protozoan parasite of seven Eimeria species causing chicken coccidiosis around the world. This species is particularly responsible for caecal coccidiosis leading to serious morbidity-mortality and financial loss in poultry production. METHODS: The present study explored the genetic diversity of E. tenella. Litter slurry was collected from 18 broiler farms located in Mymensingh district, Bangladesh. Litter samples were processed for oocyst isolation-identification using parasitological techniques followed by genomic DNA extraction from sporulated oocysts. For molecular analysis, the internal transcribed spacer 1 gene of E. tenella was amplified using species-specific primers and sequenced. After editing and alignment, 263 bp sequences were used for analysis. RESULTS: Genetic analysis showed seven distinct genotypes and detected six single nucleotide polymorphisms among the 18 E. tenella isolates. The nucleotide and genotype diversity were 0.00507 and 0.8235, respectively. A phylogenetic tree was constructed with 66 sequences (seven studied genotypes and 59 reference sequences from GenBank database). The neighbour-joining tree represented that the studied E. tenella isolates were grouped with reference E. tenella isolates with strong nodal support (100%) and the nucleotide sequences of E. tenella, E. necatrix, E. acervulina, E. brunetti, E. maxima, E. mitis and E. praecox formed separate clusters without any geographical boundaries. CONCLUSIONS: This is the first study on the genetic analysis of E. tenella from Mymensingh district, Bangladesh. These findings will provide baseline data on the species conformation and genetic variations of E. tenella. Further extensive investigation will be needed to reveal the population genetic structure of this parasite and thus will facilitate the planning of effective control strategies.

Frequency of benzimidazole resistance in Haemonchus contortus populations isolated from sheep and goats in Bangladesh.

Anthelmintic resistance against gastrointestinal nematodes especially H. contortus of sheep and goat is a global issue. To address the gravity and extension of AR in Bangladesh, genotyping of 160 adult H. contortus parasitesw ere performed to confirm benzimidazole resistance allele from different geographic zones of Bangladesh based on allele specific PCR (AS-PCR). The genotype frequencies were 9.4% for homozygous resistant (rr), 61.2% for heterozygous (rS) and 29.4% for homozygous susceptible (SS) among the selected areas. The allelic frequency of the mutation conferring resistance (r) ranged from 27.5% to 52.5% indicating substantial existence of benzimidazole resistance in H. contortus in small ruminant nematodes. Therefore, it can be concluded that genotyping the F200Y polymorphism can be used to monitor the resistance and thereby to enhance the control on the development of anthelmintic resistance against H. contortus in small ruminant nematodes.