Prevalence of Gastro-intestinal Helminths in African Elephants (Loxodonta Africana Africana) From Tsavo and Laikipia-samburu Ecosystems, Kenya

Abstract

African elephants host high numbers of helminths within their digestive tracts without them developing symptoms of disease. This has been attributed to a well-developed parasite host equilibrium. However, in times of stress, these high numbers of helminth within the gut pose a serious threat to the survival of the elephants, especially young ones. They do this by abrading the epithelial lining of the intestines, to gain access to the rich microvasculature, and unrestricted access to host ingested nutrients. Some of the helminths identified which affect elephants including Protofasciola sp and Grammocephalus sp, contribute to nutrition deprivation and serious damage to gut mucosa, during stressful conditions. This study sought to compare helminth infection patterns in elephant populations from Tsavo East National Park (TENP) and Laikipia-Samburu Ecosystem (LSE) through coprological evaluations. Helminth eggs and adult worms were identified and classified into genera using morphological and morphometric characteristics. General Linear Model (GLM), ANOVA and Chi squared test of independence were used to test for significant differences in variations of infection patterns observed, and to identify the effect of sex, age and location as risk factors in elephant populations with regard to helminth infections. Analyses in this study revealed that elephant populations from TENP and LSE have high prevalence rates for helminth infections. The populations are infected by nematodes, mostly belonging to the strongyle families; (Quilonia sp, Murshidia sp, Grammocephalus sp) and a few trematode species(Fasciola hepatica, Protofasciola robusta). Overall prevalence rates between TENP (95.62%) and LSE (98.53%) were not significantly different (χ2 =2.03, p= 0.15). Prevalence of nematode infections was 97.1% which is relatively high while trematode prevalence was lower at 32.6% (χ2 = 248.84, p<0.001). There were no significant differences in prevalence levels observed across ages; TENP (χ2 = 1.54, p= 0.46) and LSE (χ2 = 1.75, p=0.42). Family social group in LSE exhibited (100 %) prevalence rates while the male social group (93.3%), (χ2 = 4.72, p= 0.007) while there was no significant differences observed in the elephant social groups in TENP (93.9% for male social group and 97.2% for family social group) (χ2 = 0.93, p=0.335). Using Generalized Linear Model, the results indicated that age alone (p= 0.375 CI 95%) and location alone (p= 0.620, CI 95%) had no significant effect on the observed mean worm burdens as indicated by eggs per gram (EPG). Sex had a significant effect on the observed mean worm burden (p= 0.016, CI 95%), with females exhibiting higher EPGs than males. The interaction between age and location (p<0.0005, CI 95%) and age and sex (p= 0.028, CI 95%) did have significant effect on mean EPGs observed. This information should assist wildlife authorities in developing appropriate, evidence-based health monitoring and translocation protocols for proper management of the African elephant species to ensure their sustainability.