By J. Bleecker, resources from A. Plumptre (WCS) and ESA Globcover 2009
My doctoral research occurred in Kibale National Park, an evergreen rainforest in southwestern Uganda. Kibale is unique for several reasons. First, it is situated within the Albertine Rift - one of the most biodiverse regions on the planet. As a result, Kibale is rich in species, many of which remain taxonomically unclassified. This includes a high diversity and biomass of primates, with thirteen species occurring sympatrically within the park. Additionally, Kibale is surrounded by one the densest congregations of human settlements in eastern Africa, with nearly 300 people per km2 in some areas. The potential for unidentified species, the complex non-human primate community, and their close proximity to human settlements set the stage for my thesis, which examined neglected tropical parasite diversity and their potential for zoonotic transmission in and around Kibale.
The species that I studied include red colobus, black and white colobus, red-tailed monkeys, blue monkeys, l'hoest monkeys, mangabeys, baboons, and chimpanzees.
PARASITE TRANSMISSION IN A COMPLEX PRIMATE COMMUNITY
Using molecular methods, I investigated the host specificity and transmission patterns of blood parasites (hemoparasites) and parasitic worms that commonly infect both humans and non-human primates. This research is particularly interesting in the context of the Kibale community of primates, since these hosts all overlap spatially, but differ in niche occupation and degree of relatedness to one another. Therefore, I could infer what dictates the host specificity of a parasite, whether it be similarity in lifestyle or phylogenetic history.
The image below shows a summary of my findings for four parasites I investigated: the parasitic worms Trichuris (green) and Oesophagostomum (blue), and the blood parasites Hepatocystis (yellow/orange) and Plasmodium (purple). Each column of dots represents a parasite lineage that I discovered within the primate community. A dot next to the primate indicates that the parasite lineage was found in that host species. Hosts are organized by their phylogenetic relationships to one another, so that we can visualize if parasite infection breadth follows host relatedness. Overall, I found remarkable diversity in the breadth of hosts that parasites can infect -- one lineage of Trichuris was found in all species of primate sampled (including humans), while in contrast, all but one species of Heptocystis and Plasmodium were specific to a single host. This indicates that the "risk" associated with contracting parasites via contact with other species depends heavily on the parasite being investigated.
Black and white colobus (Colobus guereza)
Photo credit: D. Mills
RELATIONSHIP BETWEEN PARASITE INFECTION AND BEHAVIOR
While it seems clear that end result of an extremely virulent pathogen is death for its host, the consequences of sub-lethal parasitic infections on wildlife populations is still unclear. Using a group of red colobus monkeys that have been monitored continuously for nearly a decade, I investigated the relationship between individual behavior and their infection status. My research showed that these wild primates seemed to demonstrate "sickness behaviours", such as increases in lethargy over energetic activity. They also ate potentially medicinal plants, perhaps to expel parasitic worms or alleviate the pain of infection. Overall, this indicates that non-lethal, seemingly harmless parasites do impose consequences that may impact the fitness of hosts. Please click here to view this paper.
Cover Image: a red colobus (Procolobus rufomitratus) eating bark. Proceedings of the Royal Society B: Biological Sciences
HUMAN HEALTH & CONSERVATION
The area outside of Kibale National Park harbors a dense congregation of human settlements. We believe that the reason for this may be that people preferentially move nearer to national parks because it affords them greater opportunity for employment, and more fertile growing conditions for their crops. However, there may be a dark side to this story - it also puts them in close contact with wildlife, with whom they may share diseases. In collaboration with the Kibale Ecohealth Project and others, I investigated the implications of living adjacent to Kibale by examining disease burdens carried by the local population. This research examined the link between human health and conservation, which are two areas I am extremely interested in marrying as my research progresses.
To see some of our published work supporting unity between public health and conservation, please click here.
Many thanks to my funding sources and conservation partners