Role of monkeys in the sylvatic cycle of chikungunya virus in Senegal

Abstract

Athropod-borne viruses (arboviruses) pose the greatest risk of spillover into humans of any class of pathogens. Such spillover may occur as a one-step jump from a reservoir host species into humans or as a two-step jump from the reservoir to a different amplification host species and thence to humans. Despite the widespread havoc wreaked by emerging arboviruses, little is known about their transmission dynamics in reservoir and amplification hosts. Here we used serosurveillance and mathematical modeling to elucidate the role of monkeys in the sylvatic, enzootic cycle of chikungunya virus (CHIKV). Over three years, 219 African green monkeys, 78 patas monkeys, and 440 Guinea baboons were captured in the region surrounding Kédougou, Senegal. The age of each animal was determined by anthropometry and dentition, and exposure to CHIKV was determined by detection of neutralizing antibodies. We estimate age-specific * To whom correspondence should be addressed. Email: balthouse@idmod.org † These authors contributed equally to this work.CHIKV seroprevalence, force of infection (FoI), and basic reproductive number (R 0 ) in each species. Among the different species, CHIKV FoI ranged from 0.13 to 1.12 (95% CI, 0.81-2.28) and R 0 ranged from 1.5 (95% CI, 1.3-1.9) to 6.6 (95% CI, 5.1-10.4). CHIKV infection of infant monkeys was detected even when the virus was not detected in a concurrent survey of primatophilic mosquitoes and when population seropositivity, and therefore immunity, was too high for monkeys themselves to support continuous CHIKV transmission. We therefore conclude that monkeys in this region serve primarily as amplification rather than reservoir hosts of CHIKV. Additional efforts are needed to identify other vertebrate hosts capable of supporting continuous circulation. keywords: chikungunya virus -sylvatic arbovirus -non-human primate -age-stratified serosurvey

Potential for Zika Virus to Establish a Sylvatic Transmission Cycle in the Americas

“…We explore three per-bite infection probabilities (0.3, 0.6, 0.9) with an average of 0.5 bites per day. This gives forces of infection 0.15, 0.3, 0.45, which is in line with observed sylvatic DENV forces of infection from primate collections in Kedougou, Senegal in 2010-2012 [59]. These forces of infection ranged from 0.09 (95% CI: 0.07, 0.11) for Guinea baboons ( Papio papio ) in 2012, to 0.41 (95% CI: 0.26, 0.76) for African green monkeys ( Chlorocebus sabaeus ) in 2012.…”