The domestic pig, Sus scrofa domesticus, is reared in most parts of the world for provision of pork, biomedical raw materials and manure. Pork constitutes about 44% of meat consumed globally (FAO, 2015). Nigeria is the leading producer of pig in the West African Sub-region, responsible for about nine million pigs, which represent 64.3% of the 14 million pigs reared in the Sub-region (Ajibo et al., 2020). In Nigeria, pig production activities are concentrated in the southern and middle-belt regions, due to religious or cultural restrictions to pig farming and consumption of pork in most parts of the North (Nwanta et al., 2011; Ajibo et al., 2020).
Consequently, pig farming is the second largest agribusinesses in Enugu State, where pig rearing is undertaken as an alternative source of income or precautionary measure against crop failure (Njoga et al., 2018a; Njoga et al., 2019). The polytocous nature, high feed conversion efficiency, early maturing nature, short gestation length and ability to thrive under sub-optimal tropical conditions confer pig comparative advantages over other food-producing animals. In addition, pig farming has the advantage of economy of space compared to ruminant productions. Moreover, the ease in the marketability of pork in most parts of the world seems to guarantee speedy returns on any investment in the swine industry (Nwanta et al., 2011).
Despite these comparative advantages, pig production in Enugu State, Nigeria is not thriving as expected, due to the endemicity and high burden of helminths that greatly limit productivity and profitability in swine production (Abonyi and Njoga, 2020). Helminthiasis has continued to constrain pig production in Nigeria due to abundance and interconnectivity of epidemiological factors and farm practices enhancing survival and transmission of the parasites (Ajibo et al., 2020). Pigs are at risk of gastrointestinal worm infections (GWI) due to their gluttonous appetite and omnivorous feeding habit (Onunkwo et al. 2011) especially when farmers are ignorant of biosecurity practices or do not prioritize them. One major problem associated with GWI in the pig industry is that it limits pork production and hence contributes to diminution of animal protein, especially in developing countries where the demand lags behind the supply (Ekere et al., 2018; Njoga et al., 2018b).
In both humans and animals, the symptomatology or clinical manifestations of helminthiasis may be similar. Low GWI may present no clinical sign or symptom. However, heavy or even mild infections may give rise to malnutrition, diarrhoea, dysentery, abdominal pain, emesis, in-appetence, thriftiness, general malaise, tiredness, impaired cognitive development and growth retardation in children (Ojha et al., 2014; Mulambalah and Ruto, 2016; Ajibo et al., 2020). Anaemia as a result of petechial hemorrhage and decreased intestinal iron absorption due to the attachment sites of the parasites can result following chronic hookworm infections (Cross, 1996).
Helminthiasis in piggeries connotes economic losses, specifically as regards costs of anthelmintics and veterinary services. In addition, the sequelae of GWI such as poor weight gain, emaciation, infertility problems, reduced liter size and delay in maturity or attainment of market weight imply economic wastages (Roesel et al., 2017); since the pigs have to be reared and fed for a longer period (Abonyi and Njoga, 2020). Furthermore, some pig parasites especially the Ascaris spp damage visceral organs, and hence may cause substantial financial losses due to condemnation of the damaged organs, during meat inspection in abattoirs (Ajibo et al., 2020).
Apart from the financial losses, some pig worms are zoonotic. Irrespective of host preferences, A.suum and A.lumbricoides have been shown to spread from pigs to humans and vice versa (Peng and Criscione, 2012). These parasites make pork unsafe for human consumption and deter the sale or consumption of such pork or the products. High infection with Ascaris spp is characterized by anorexia, stunted growth, pot-belly syndrome, intestinal obstruction and impaired cognitive function in children (Mulambalah and Ruto, 2016; Ajibo et al., 2020). Cases of ascariasis are common in the Sub-Saharan Africa due to the synergy of climatic factors, unhygienic practices and high fecundity of the parasite (Abonyi and Njoga, 2020), capable of releasing over 200,000 eggs per matured female per day (Vlaminck et al., 2014).
Despite the importance of GWI, epidemiological data on the occurrence of the infection and the transmission dynamics are sparse in Enugu State; notwithstanding wide-spread pig farming activities in the area. These data are imperative for effective control strategies against the infections. Therefore, this study determined the epidemiology of GWI in pigs reared in Enugu State and their effects on the production parameters. The findings will help to limit spread of the infections, boost pig production and hence the availability of safe and wholesome pork for human consumption.