Epidemiological study of zoonoses derived from humans in captive chimpanzees

Abstract

Emerging infectious diseases (EIDs) in wildlife are major threats both to human health and to biodiversity conservation. An estimated 71.8 % of zoonotic EID events are caused by pathogens in wildlife and the incidence of such diseases is increasing significantly in humans. In addition, human diseases are starting to infect wildlife, especially non-human primates. The chimpanzee is an endangered species that is threatened by human activity such as deforestation, poaching, and human disease transmission. Recently, several respiratory disease outbreaks that are suspected of having been transmitted by humans have been reported in wild chimpanzees. Therefore, we need to study zoonotic pathogens that can threaten captive chimpanzees in primate research institutes. Serological surveillance is one of several methods used to reveal infection history. We examined serum from 14 captive chimpanzees in Japanese primate research institutes for antibodies against 62 human pathogens and 1 chimpanzee-borne infectious disease. Antibodies tested positive against 29 pathogens at high or low prevalence in the chimpanzees. These results suggest that the proportions of human-borne infections may reflect the chimpanzee's history, management system in the institute, or regional epidemics. Furthermore, captive chimpanzees are highly susceptible to human pathogens, and their induced antibodies reveal not only their history of infection, but also the possibility of protection against human pathogens.

Fig. 1

Seroprevalence and titres of B. pertussis and MV antibodies, obtained by use of BAT and HI, respectively, for 14 chimpanzee serum samples. The range of antibody titre against B. pertussis was broad (40–5120×), and the average titre for the SB group (chimpanzees reared in KUPRI since birth) was higher than that for the AB group (chimpanzees reared in KUPRI after birth). MV antibody titre ranged from 16× to 64×, and most positive chimpanzees were in the AB group (in the SB group only one chimpanzee was positive: 64×). The hollow box indicates SB, and the solid box indicates AB. The bars indicate the average (Av.)

Fig. 2

Seroprevalence and titres of hPIV-3, hMPV, and RSV antibodies obtained by use of HI and ELISA (second two) for 14 chimpanzee serum samples. The titre against hPIV-3 for SB chimpanzees ranged from 20× to 80×, and that for the AB chimpanzees ranged from 80× to 160×. The average titre for the SB group was lower than that for the AB group. The titre against hMPV for SB chimpanzees ranged from 400× to 800×, which was lower than that for AB chimpanzees (3200–12800×). The average titre for the SB group was also lower than that for the AB group. The titre against hRSV ranged broadly from 800× to 12800× for both SB and AB chimpanzees. Average titres for SB chimpanzees were not much higher than those for AB chimpanzees. The hollow box indicates SB, and the solid box indicates AB. The bars indicate the average (Av.)

Fig. 3

Seroprevalence and titres of CMV, VZV, EBV, and HHV6 antibodies obtained by use of EIA for 14 chimpanzee serum samples. The antibody titre against CMV ranged from 17× to 32× for SB chimpanzees and from 26× to 51× for AB chimpanzees. The average titres in SB chimpanzees were lower than those in AB chimpanzees. The antibody titre against VZV in SB chimpanzees ranged from 5.0× to 42.7×; that in AB chimpanzees ranged from 5.1× to 13.6×. The antibody titre against EBV ranged from 5.5× to 12× for the SB group, which was not much higher than that for the AB group (5×–14×). The antibody titre against HHV6 ranged from 20× to 160× for SB chimpanzees and from 20× to 40× for AB chimpanzees. Differences in the average titres of VZV, EBV, and HHV6 were not statistically significant between SB and AB chimpanzees. The hollow box indicates SB, and the solid box indicates AB. The bars indicate the average (Av.)

Fig. 4

a Seroprevalence of antibodies against picornaviruses, CVB-2, CVB-3, CVB-6, echovirus-3, echovirus-6, CVA-5, CVA-6, CVA-7, CVA-9, and PV-1 for each chimpanzee. The antibodies in serum were detected by use of NT. The AB female Mari had antibodies against four picornaviruses (CVB-3, CVB-6, CVA-5, and CVA-7); the AB male Akira had antibodies against CVB-2, echovirus-6, and CVA-7. Abbreviations of each chimpanzee name are listed in Table 1. b The seroprevalence of antibodies against HAV and JEV for each chimpanzee detected by use of CLIA for HAV and CF for JEV. Antibody against JEV was detected in both SB and AB chimpanzees, but HAV was detected in AB chimpanzees only