Spatial and Temporal Dynamics of a Mortality Event among Central African Great Apes

Abstract

In 2006–2007 we observed an unusual mortality event among apes in northern Republic of Congo that, although not diagnostically confirmed, we believe to have been a disease outbreak. In 2007–2011 we conducted ape nest surveys in the region, recording 11,835 G. g. gorilla nests (2,262 groups) and 5,548 P. t. troglodytes nests (2,139 groups). We developed a statistical model to determine likely points of origin of the outbreak to help identify variables associated with disease emergence and spread. We modeled disease spread across the study area, using suitable habitat conditions for apes as proxy for local ape densities. Infectious status outputs from that spread model were then used alongside vegetation, temperature, precipitation and human impact factors as explanatory variables in a Generalized Linear Model framework to explain observed 2007–2011 ape nest trends in the region. The best models predicted emergence in the western region of Odzala-Kokoua National Park and north of the last confirmed Ebola virus disease epizootics. Roads were consistently associated with attenuation of modeled virus spread. As disease is amongst the leading threats to great apes, gaining a better understanding of disease transmission dynamics in these species is imperative. Identifying ecological drivers underpinning a disease emergence event and transmission dynamics in apes is critical to creating better predictive models to guide wildlife management, develop potential protective measures for wildlife and to reduce potential zoonotic transmission to humans. The results of our model represent an important step in understanding variables related to great ape disease ecology in Central Africa.

Status of Road Ecology Research in Africa: Do We Understand the Impacts of Roads, and How to Successfully Mitigate Them?

“…Our review revealed many more road ecology publications from Africa than we expected, with a significant increase in the number of publications since 2006. Most of the publications were from the more affluent and politically stable regions (e.g., southern and East Africa), particularly pre-2006 publications (Drews, 1995;Dean and Milton, 2000), whilst post-2006 publications saw an increase in the number of papers from Central Africa (Hicks et al, 2012;Tompkins et al, 2015;Cameron et al, 2016).…”

Assessment of in situ nest decay rate for chimpanzees (Pan troglodytes ellioti Matschie, 1914) in Mbam-Djerem National Park, Cameroon: implications for long-term monitoring

“…As a consequence of all these factors, great ape populations have experienced a precipitous decline within the last 40 years (Fruth and Hohmann 1996;Walsh et al 2003;Williamson et al 2013). Thus, large-scale conservation measures are needed urgently in order to avoid further decline of great ape populations as well as to mitigate the various threats (Spehar et al 2010;Cameron et al 2016).…”

Ebola in great apes – current knowledge, possibilities for vaccination, and implications for conservation and human health

“…, Cameron et al. ). Identification of the virus's true reservoir and infection pathways in nature remains important research (Leendertz ).…”

“…Such monitoring has been shown to be a prerequisite for the early detection and effective sampling of suspected cases of EVD (Leendertz et al 2006, Travis et al 2008; laboratory analysis is the only way to confirm Ebola infection. Antibody testing of non-invasively collected great ape samples can show which populations have been exposed to the virus, and surveys to estimate group density and population numbers may provide information about population declines possibly caused by Ebola (Campbell et al 2008, Kouakou et al 2009, Olson et al 2012a,b, Reed et al 2014, Cameron et al 2016). Identification of the virus's true reservoir and infection pathways in nature remains important research (Leendertz 2016).…”