Human coronavirus OC43 outbreak in wild chimpanzees, Côte d´Ivoire, 2016

Dear Editor, A number of pathogens have been described to circulate between humans and non-human primates. The close relatedness between these hosts is thought to support pathogen transmission. Due to their rapid spread and difficult containment, airborne pathogens raise the greatest concerns. Common human respiratory viruses such as the human respiratory syncytial virus (HRSV), the human metapneumovirus (HMPV) and the human rhinovirus C, have caused lethal outbreaks in wild habituated great apes. Strict prevention measures have been adopted to mitigate the risk of disease introduction at great ape research sites, allowing habituation programmes to maximize positive effects on wildlife conservation. However, transmission of infectious agents may still occur. Here we report the transmission of the human coronavirus (HCoV) OC43 to wild chimpanzees (Pan troglodytes verus) living in the Taï National Park, Côte d ́Ivoire. These chimpanzees are habituated to human presence, and are in the focus of long-term observatory studies since the ’80s. All members of the three communities (North, South and East) are individually known. Between late December 2016 and early January 2017, a mild respiratory outbreak was observed in the East chimpanzee community (currently composed of 33 individuals). Daily monitoring by trained personnel identified sporadic coughing and sneezing throughout the group, mainly in morning hours. No other symptom was observed. Factors such as forest density, chimpanzee group fission–fusion and amount of time spent on the ground vs. on trees strongly influence whether individuals can be observed on a daily basis. In such conditions, the detection of disease onset and follow-up of symptoms’ course over time as well as the collection of samples is very complicated. During this outbreak, symptoms were reported once in at least nine individuals; of these, six were consistently identified as symptomatic on three consecutive days (Fig. 1, bold names). Fecal samples were collected as part of a continuous non-invasive health monitoring program and shipped to the Robert Koch Institute for analyses. To expand our window of investigation to non-outbreak times, a total of 59 samples collected from 18 individuals of this community between November 2016 and February 2017 were tested. This number reflects all available samples for the time frame of interest. We performed a PCR screening targeting major respiratory viruses including HRSV and HMPV, adenoviruses (AdVs), coronaviruses, enteroviruses, influenza A and B viruses, parainfluenza viruses and rhinoviruses. PCR and sequencing identified the HCoV-OC43 in 14/ 59 samples, collected from 11 individuals, including those where symptoms were consistently reported (Fig. 1). HCoV-OC43 positive samples were collected within the time frame of observed respiratory disease outbreak, whereas samples collected before and after were negative. The detection in feces exclusively during the outbreak supports the hypothesis of this coronavirus being responsible for the observed mild respiratory symptoms. With the exception of AdVs, all other tests were negative. Adenoviruses were however detected in 49/59 samples across outbreak and non-outbreak times. Along with the evidence of AdVs being widely carried by wild great apes and shed in feces, the continuous detection points towards an unlikely involvement in this outbreak. Since 2008, the Taï Chimpanzee Project has implemented a mandatory quarantine for any individual intending to approach the chimpanzees. To control for