Association Between Helminth Burden, Helminth Species Richness, Body Condition, Haematological Profile and Spleen Morphometrics in Domestic Guinea Fowl (Numida meleagris)

Abstract

The economic, physiological and immunological costs of endo-parasitism are documented to be higher in poultry with greater parasite intensities and diversity. The current study was undertaken to determine the effects of helminth burden in domestic guinea fowls at quantified natural infestation levels on body condition, haematological profile and spleen morphometrics. We hypothesized that the spleen size and haematological parameters would be correlated to both total helminth burdens and species richness per host. All guinea fowls were infected with gastrointestinal nematodes (147/147). Mean intensity of nematode infection was 113.7 (CI 98.9-128.6) and the average species richness was 4.17 species/host (Range 1 to 7). Although helminth species richness was positively associated with spleen size and weight, the study showed no compelling evidence (p<0.05) of association with total worm count per host. There was no association between body weight and helminth species richness but a positive association between total worm counts per host and body weight with heavier guinea fowls having more worms per host. Packed cell volume (PCV) was mildly negatively associated with helminth species richness but total worm count was paradoxically positively associated with PCV in male guinea fowl. All haematological values at different worm burdens and species richness were however, within reference values. Collectively, these findings may suggest that the most common helminths at natural infection levels in free-living guinea fowl populations have minimal or symbiotic effect on the immune system of the host. However, experimental trickle infections with different helminth species to reach natural infestation levels, up to clinical disease levels, are required to better understand the progression of immune responses to helminths in guinea fowls and evaluate the potential consequences on their health. Research studies leading to a comprehensive understanding of the effects of helminths on the host's immune system will have a bearing on the pre-requisite preparations preceding and the responses to, immunization in poultry.