The Role of Host Demographic and Environmental Factors in Gastrointestinal Parasites in (…)

ABSTRACT

The giraffe (Giraffa spp.) is an iconic mega-herbivore native to sub-Saharan Africa. Historically, its range cuts across 22 countries in sub-Saharan Africa. Since the 1990s, giraffe populations in Kenya have declined by approximately 25%–30%, dropping from an estimated 155,000 individuals to around 90,000 individuals by 2020. The primary drivers of this declining trend are habitat loss and fragmentation, poaching, civil unrest, disease and climate change. Rothschild's giraffes (Giraffe camelopardalis rothschildi) now a subspecies of the Northern giraffe (Giraffe camelopardalis) is listed as globally Near Threatened by the IUCN with a national population of less than 2500 individuals left. Host demographic factors such as age, sex, social structure, together with environmental variables including temperature, rainfall and vegetation cover play a critical role in shaping the occurrence, transmission and intensity of gastrointestinal parasites in wildlife populations. The aim of this study was to assess the occurrence of intestinal helminths in Rothschild's giraffes (Giraffa camelopardalis rothchildi) populations in Kenya. Specifically, this study determined the relationship between host demographic factors (sex, age, social structure), temperature, rainfall, NDVI (normalized difference vegetation index), management regimes and the infection levels within the Rothschild's giraffe populations. Faecal samples were collected opportunistically from giraffes and stored in 10% formalin for preservation. The samples were then processed under a microscope during floatation, Mc Master and sedimentation techniques. A high gastrointestinal parasite prevalence among giraffes was observed across all study sites (92.8% at Ruma, 100% at Giraffe Centre and 85.4% at Soysambu Conservancy) with no statistically significant differences detected among locations (χ ² = 5.42, df = 2, p = 0.066). Strongyle-type parasite had the highest prevalence of 95.2%, whereas Taenia spp had the lowest prevalence of 0.3%. Despite the lack of association between parasite infection (diversity and load) and age, sex and social structure, male individuals in family groups had higher parasite load compared to male individuals in bachelor herds. The chi-square test indicated no significant difference in prevalence across the three study sites (χ ² = 5.42, df = 2, p = 0.066). GLM analyses revealed that three-month mean NDVI, temperature and rainfall positively influenced the load and diversity except for temperature that did not have a significant effect on the parasite diversity. Therefore, our results will assist to understand the dynamics of parasites in the Near Threatened Rothschild's giraffes and allow for the development of appropriate measures towards conserving the subspecies.