Cryptic Eimeria genotypes are common across the southern but not northern hemisphere

Abstract

Graphical abstract

Mitochondrial genomes of Australian chicken Eimeria support the presence of ten species with low genetic diversity among strains

“…Phylogenetic trees based on ribosomal ITS2 sequences have suggested OTU-Z might be sister to E. necatrix and E. tenella (Fornace et al, 2013), however Schwarz et al,(2009) andClark et al, (2016) published a different topology using the same marker which highlights the importance of outgroup selection and sequence alignments. Chicken Eimeria display high within individual variability in the ribosomal internal transcribed spacers and length differences make sequence alignments for phylogenetic comparisons difficult for this marker (Lew et al, 2003).…”

“…In Australia a further three operational taxonomic units (OTU) were characterized by Cantacessi et al, in 2008(Cantacessi et al, 2008. Little is known about the prevalence or distribution of these OTU although all three cryptic species have now been identified in flocks from Africa (Clark et al, 2016;Fornace et al, 2013) and a recent global survey of Eimeria suggests they may be widespread in the southern hemisphere, but not the northern (Clark et al, 2016) . It is unlikely that the OTU, or any of the chicken infecting Eimeria species, originated in Australia as chickens have only been present in the country since European settlement in the late 18 th century.…”

Application of a new PCR-RFLP panel suggests a restricted population structure for Eimeria tenella in UK and Irish chickens

“…In contrast, E. tenella populations sampled north of this latitude presented limited haplotype diversity with significant disequilibrium (Blake et al, 2015). More recent analysis of internal transcribed spacer (ITS) sequence diversity for E. tenella has confirmed this apparent variation in population structure, with notably limited diversity detected in the United States of America (USA) (Clark et al, 2016). While these data are informative, expanding research to E. tenella populations in other regions and laboratories requires a more accessible technique.…”

Eimeria species occurrence varies between geographic regions and poultry production systems and may influence parasite genetic diversity

“…In recent studies of E. tenella occurrence around the world, the parasite was found to be common in all regions that were sampled (Clark et al, 2016). However, detailed investigation of E. tenella recovered from Egypt, India, Libya and Nigeria, demonstrated dramatically different levels of genetic diversity and population structures between regions (Blake et al, 2015).…”