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Nematodes of the genus Ascaridia are known to infect many species of birds and result in fatal diseases. A. galli damages the intestinal mucosa of chickens leading to blood loss, secondary infection and occasionally the obstruction of small intestines due to high worm burden. This study investigated the gene expression profiles in chickens from two different provinces of South Africa naturally exposed to A. galli infestations and tested either positive or negative for the parasite. The study further investigated gene expression profiles of the A. galli infected duodenum, jejunum and ileum tissues of the small intestines. The A. galli positive intestines displayed hypertrophy of the intestinal villi with accumulation of inflammatory cells and necrosis of the crypts of Lieberkühn glands, lesions that were absent in the uninfected intestines. Total RNA isolated from small intestines of infected and non-infected intestines was sequenced using Illumina HiSeq technology to generate up to 23,856,130 reads. Between any two-way comparisons of the intestines, 277 and 190 transcripts were significantly expressed in Limpopo and KwaZulu-Natal (KZN) chickens, respectively. Gene ontology analysis of the differentially expressed genes (DEGs) revealed an enrichment of genes reported to function in the immune response, defense response, inflammatory response and cell signalling genes. T cell receptor signalling pathways and arachidonic acid metabolism pathways were among the most significantly impacted pathways. Overall, the study provided insights into adaptative mechanisms for chickens extensively raised in parasite infected environments., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

A longitudinal study was conducted in low-input low-output farming systems to determine the prevalence of gastrointestinal parasitic infections in different age groups, sex and associated risk factors in goats. A total of 580 indigenous goats were randomly selected in areas representing the five agro-ecological regions of Zimbabwe in the dry and wet seasons. Blood and faecal samples were collected from each animal and egg/oocyst per gram of faeces (epg/opg), larval culture, and packed cell volumes (PCV) were determined. Factors affecting parasitic infections were evaluated. Highest prevalence was determined for Eimeria oocysts (43%), strongyles (31%) and lower levels in trematodes and cestodes. Parasites identified were Haemonchus, Strongyloides and Oesophagostomum. Area, season, sex and age significantly influenced patterns of gastrointestinal infections ( P   <  0.05). Cannonical correlations indicated that parasite species composition varied by area and impacts of risk factors also differed. Risk of infection was very high for goats sampled in Natural regions (NR) I, II, III (OR = 6.6-8.2; P  < 0.05) as compared to those in NR IV and V. Highest helminths and Eimeria infections were observed in the wet vs. dry season ( P   <  0.05). Young animals were more susceptible to parasitic infections ( P   <  0.05). Prevalence was higher in males than females, with odds of infection for males being almost three times to that for females ( P   <  0.0001). Knowledge concerning gastrointestinal helminth biology and epidemiological infection patterns caused by these parasites is essential in the development of appropriate control strategies and this has a potential to reduce production losses.

The control of gastrointestinal nematodes (GIN) is mainly based on the use of drugs, grazing management, use of copper oxide wire particles and bioactive forages. Resistance to anthelmintic drugs in small ruminants is documented worldwide. Host genetic resistance to parasites, has been increasingly used as a complementary control strategy, along with the conventional intervention methods mentioned above. Genetic diversity in resistance to GIN has been well studied in experimental and commercial flocks in temperate climates and more developed economies. However, there are very few report outputs from the more extensive low-input/output smallholder systems in developing and emerging countries. Furthermore, results on quantitative trait loci (QTL) associated with nematode resistance from various studies have not always been consistent, mainly due to the different nematodes studied, different host breeds, ages, climates, natural infections versus artificial challenges, infection level at sampling periods, among others. The increasing use of genetic markers (Single Nucleotide Polymorphisms, SNPs) in GWAS or the use of whole genome sequence data and a plethora of analytic methods offer the potential to identify loci or regions associated nematode resistance. Genomic selection as a genome-wide level method overcomes the need to identify candidate genes. Benefits in genomic selection are now being realised in dairy cattle and sheep under commercial settings in the more advanced countries. However, despite the commercial benefits of using these tools, there are practical problems associated with incorporating the use of marker-assisted selection or genomic selection in low-input/output smallholder farming systems breeding schemes. Unlike anthelmintic resistance, there is no empirical evidence suggesting that nematodes will evolve rapidly in response to resistant hosts. The strategy of nematode control has evolved to a more practical manipulation of host-parasite equilibrium in grazing systems by implementation of various strategies, in which improvement of genetic resistance of small ruminant should be included. Therefore, selection for resistant hosts can be considered as one of the sustainable control strategy, although it will be most effective when used to complement other control strategies such as grazing management and improving efficiency of anthelmintics currently., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)

Ascaridia galli is one of the most common nematode affecting chickens. This study characterized A. galli parasites collected from South African village chickens of Limpopo (n=18) and KwaZulu-Natal (n=22) provinces using the 510bp sequences of cytochrome C oxidase subunit 1 gene of the mitochondrial DNA. Fourteen and 12 polymorphic sites were observed for Limpopo and KwaZulu-Natal sequences, respectively. Six haplotypes were observed in total. Haplotype diversity was high and ranged from 0.749 for Limpopo province to 0.758 for KwaZulu-Natal province isolates. There was no genetic differentiation between A. galli from Limpopo and KwaZulu-Natal provinces. The six South African haplotypes were unique compared to those published in the GeneBank sampled from Hy-line chickens raised under organic farming in Denmark. The utility of cytochrome C oxidase subunit 1 gene as a potential genetic marker for studying A. galli in village chicken populations is presented., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The objectives of this study were to analyze the genetic diversity and structure of South African conserved and field chicken populations and to investigate the maternal lineages of these chicken populations. Four South African conserved chicken populations (n = 89), namely, Venda (VD&#95;C), Ovambo, Naked Neck, and Potchefstroom Koekoek from the Animal Production Institute of the Agricultural Research Council, and 2 field populations, the Venda and Ovambo (OV&#95;F), from which the Ovambo and the Venda conservation flocks were assumed to have been sampled, were genotyped for 460 bp of the mitochondrial DNA (mtDNA) D-loop sequence. Haplotypes of these chickens were aligned to 7 Japanese and 9 Chinese and Eurasian chicken mtDNA D-loop sequences taken from GenBank and reflecting populations from presumed centers of domestication. Sequence analysis revealed 48 polymorphic sites that defined 13 haplotypes in the South African chicken populations. All 6 South African conserved and field chicken populations observed were found to be polymorphic, with the number of haplotypes ranging from 3 for VD&#95;C to 8 for OV&#95;F. The lowest haplotype diversity, 0.54 ± 0.08, was observed in VD&#95;C chickens, whereas the highest value, 0.88 ± 0.05, was observed in OV&#95;F chickens. Genetic diversity between the 4 South African conserved and 2 field chicken populations constituted 12.34% of the total genetic variation, whereas within-population diversity constituted 87.66% of the total variation. The median network analysis of the mtDNA D-loop haplotypes observed in the South African conserved and field populations and the reference set resulted in 5 main clades. All 6 South African chickens were equally represented in the major clade, E, which is presumed to be of Indian subcontinent maternal origin and may have its roots in Southeast Asia. The results showed multiple maternal lineages of South African chickens. Conservation flocks and field chicken populations shared the major haplotypes A, D and E, which were presumed to be of Chinese, Southeast Asian, and Indian subcontinental origin.