Vector incrimination and transmission of avian malaria at an aquarium in Japan: mismatch in parasite composition between mosquitoes and penguins.

BACKGROUND: Captive populations of penguins outside of their natural distributions are often maintained in outdoor facilities, such as zoos and aquariums. Consequently, such penguins in captivity are constantly exposed to mosquito vectors and risk of avian malarial infection during their active period from spring to autumn, which can be lethal to these naïve birds. Previous studies have investigated parasite prevalence in mosquitoes or penguins, but simultaneous investigations, which would be crucial to monitor the transmission dynamics and cycle within a facility, have not been done. To identify dominant lineages and trends, multiple-year surveys are recommended. METHODS: Avian malaria parasites (Plasmodium spp.) and related haemosporidia were tested in penguins and mosquitoes at an aquarium in Japan through multiple years from 2011 to 2018. Prevalence and dynamics were confirmed, and molecular analyses targeting the protozoal cytb gene were used to reveal the transmission cycle. Blood meals of mosquitoes were also identified using molecular methods. RESULTS: Parasite detection in penguins tended to fluctuate within an individual. Two Plasmodium lineages were consistently detected in mosquitoes that had fed on penguins and wild birds observed around the aquarium. Plasmodium lineage CXPIP09 was detected from both mosquitoes and penguins, suggesting active transmission at this facility. However, Plasmodium cathemerium PADOM02 was only detected in mosquitoes, which may be due to host, vector or parasite-related factors, or detection methods and their limits. Additionally, Haemoproteus larae SPMAG12 was detected from penguins, suggesting active transmission via biting midges. CONCLUSIONS: The mismatch in parasite composition between penguins and mosquitoes shows that multiple aspects such as captive birds, wild birds and vector insects should be monitored in order to better understand and control avian malarial infection within ex-situ conservation facilities. Furthermore, morphological analyses would be needed to confirm competency and infection dynamics of avian malaria parasites.

Detection of avian haemosporidia from captive musophagid birds at a zoological garden in Japan.

One captive musophagid bird at a zoological garden in Japan showed clinical symptoms and was found to be infected with avian haemosporidia. We subsequently collected blood from all musophagid birds kept in the garden and examined for avian haemosporidia using both microscopic and molecular examination. Only Haemoproteus gametocytes were observed in the blood of two Guinea turaco (Tauraco persa). Three genetic lineages of Haemoproteus were identified from three Guinea turacos and one genetic lineage of Leucocytozoon was identified from a grey plantain-eater (Crinifer piscator). Detected Haemoproteus lineages were all identical and completely different from those previously reported in Japan, suggesting that these birds were infected in their original habitat. This is the first record of Haemoproteus infection in Guinea turacos.