Grooming and its effect on the prevalence of tick borne diseases: a case study of wild yellow baboons (papio cynocephalus cynocephalus)

Abstract

Behavioral studies on grooming in nonhuman primates have been carried out by several primatologists over the years. Nonhuman primates spend a lot of time grooming for various reasons which include health and social functions. These nonhuman primates are exposed to ectoparasites in the wild which include ticks that act as vectors in the transmission of several diseases including haemoparasitic infections in animals. This study aimed at determining whether there is a relationship between the frequency of grooming received by a baboon and its ectoparasite load. It also aimed to find out whether reduced ectoparasite load results in lower prevalence of haemoparasitic infections transmitted by ticks. The study focused on a population of wild yellow baboons (papio cynopcephalus cynocephalus), and examined the relationship, in each study subject, between grooming behavior, tick load, and haemoprotozoan infection status. The methodology included ad libitum and focal sampling methods of measuring grooming behavior; it also included darting and physical examination of animals for disease indicators, haematological laboratory examination of samples such as blood smears, packed cell volume (PCV) determination, and molecular diagnosis of haemoparasites using polymerase chain reaction (PCR). Data management and analysis was carried out using STATAl 0 statistical software. The results showed that the frequency of grooming received was influenced by the age, rank, sex and the social group to which an individual animal belonged. The ectoparasite load was influenced mainly by the age of the animal such that older animals were more likely to have a higher tick load compared to the younger ones (p = 0.025, Odds Ratio = 1.118, n = 59), and to a lesser extent it was also influenced by the frequency of grooming received (p = 0.083, Odds Ratio = 0.968, n = 59) and dominance rank (p = 0.056, Odds Ratio = 0.870, n = 59). The results also showed a low prevalence of Babesia species in this population of animals. The physical examination did not reveal any signs of acute infection by this parasite. Other physiological x indices of the presence of infection such as packed cell volume were affected by the ectoparasite load, age and sex. The data strongly suggested a relationship between grooming and tick load, such that animals that were groomed more had fewer ticks. The effect was significant in a fnonparametric bivariate test of total tick count versus grooming (p = 0.0036), and showed a strong trend in a multivariate analysis using a categorical variable (ticks present vs ticks absent; p = 0.086). However, the results did not reveal any significant relationship between haemoprotozoan infections verses grooming.