INTRODUCTION
Livestock contribute to the food supply of humans on a daily basis. They provide a major source of proteins and vitamins that are important for normal health and sustenance but livestock faces several health challenges in the environment. They feed on several varieties of substances; food particles – earthworms, snails, ants, cockroaches, which may be infected by microorganism and parasites leading to debilitating consequences. Although livestock includes ruminants and birds, birds especially chicken show more proximity to man and get plagued too often by gastrointestinal parasites (Abebe et al., 2016; Wuthijaree et al., 2019; Van et al., 2020; Bandi et al., 2020).
This parasitic infections of the gastrointestinal tract, although caused by a number of parasites; Eimeria species, cestodes, nematodes their prevalence is quite alarming (Nematodes and cestodes 65.5%; Ascaridia galli 65 (32.5%), Heterakis gallinarum 38 (19.0%), and Capillaria spp. 29 (14.5%), Cestodes; Raillietina spp. 19(9.5%), Choanotaenia infundibulum 2.5%, Prosthogonimus spp. 1.5%) and has impacted substantially, the production of chickens. Every community has poultries for the rearing of chickens, markets for their sale and abattoirs for their slaughter, studies on post-mortem analysis of chickens are widely available and they have portrayed the tremendous losses caused by infections due to gut parasites which reduce the body size (35%), decreases egg production and fertility (22%) andeventual death (40%) (Opara et al., 2014; Abebe et al., 2016; Wuthijaree et al., 2019; Imam et al., 2017; Ola-Fadunsin et al., 2019; Van et al., 2020; Bandi et al., 2020).
Studies are also available on the enumeration of parasites from the gastrointestinal tract (Agishi et al., 2016; Adelusi et al., 2018; Wokem and Obiyor, 2018; Ogbaje et al., 2019; Abah et al., 2019). This review intends to asses these studies in other to identify the background surrounding the prevalence of gastrointestinal parasites of chicken, although the review is limited to gastrointestinal parasites of chicken, the findings will be valuable as a contribution to knowledge; it will impact poultry management systems; environmental agencies and provide a background for future studies.