Malaria outbreaks in Humboldt penguins and haemosporidian infections in avian hosts in zoos across Thailand
1
Issued Date
2026-01-01
Resource Type
eISSN
2667114X
Scopus ID
2-s2.0-105027397397
Journal Title
Current Research in Parasitology and Vector Borne Diseases
Volume
9
Rights Holder(s)
SCOPUS
Bibliographic Citation
Current Research in Parasitology and Vector Borne Diseases Vol.9 (2026)
Suggested Citation
Rahmah S.A., Jairak W., Thanee S., Saedan A., Mahadthai P., Novianto D., Saiwichai T., Kaneko O., Pattaradilokrat S., Kaewthamasorn M. Malaria outbreaks in Humboldt penguins and haemosporidian infections in avian hosts in zoos across Thailand. Current Research in Parasitology and Vector Borne Diseases Vol.9 (2026). doi:10.1016/j.crpvbd.2026.100352 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/114703
Title
Malaria outbreaks in Humboldt penguins and haemosporidian infections in avian hosts in zoos across Thailand
Corresponding Author(s)
Other Contributor(s)
Abstract
Haemosporidian parasites are increasingly being recognized as emerging threats to avian populations, with the potential to cause severe morbidity, leading to population decline, and even extinction in susceptible species. In February 2022, a Humboldt penguin (Spheniscus humboldti) housed at a zoo in northeastern Thailand died, later confirmed to be due to avian malaria infection. The same year, four more deaths occurred between July and November. This study aimed to (i) determine if these infections extended beyond the affected penguins to other avian species housed at the same or at other zoos across Thailand, and (ii) explore the potential genetic relationships between the parasite lineages detected in this study and those reported previously across the world. A total of 406 blood and tissue samples from 146 Humboldt penguins and 260 individuals representing ten avian orders (38 species) were collected from six zoos nationwide. Nested PCR assays amplifying the mitochondrial cytochrome b gene (cytb) were performed, and the positive amplicons were confirmed by Sanger sequencing and BLASTn similarity searches. Phylogenetic analyses and tripartite network visualizations of parasite lineages, host species, and sample origins were used to assess the inter-lineage correlations. Exoerythrocytic meronts were observed within the cytoplasm of the Kupffer cells, consistent with an active haemosporidian infection. Molecular screening detected haemosporidian DNA in 40 of the 146 penguin samples (27.4%) and in 125 of the 260 samples from other avian species (48.0%). These included taxa listed on the International Union for Conservation of Nature (IUCN) Red List, most notably the Malayan peacock-pheasant (Polyplectron malacense), the green peafowl (Pavo muticus), and the white-rumped vulture (Gyps bengalensis), classified as critically endangered. The identified parasites comprised four confirmed Plasmodium species (P. collidatum, P. relictum, P. juxtanucleare, and P. gallinaceum) as well as seven Plasmodium lineages. In addition, Haemoproteus sacharovi, four Haemoproteus lineages, and Leucocytozoon caulleryi were detected. Several of these parasites have been reported in domesticated and wild birds in Thailand and other countries, suggesting an ongoing circulation among avian populations. These findings emphasize the urgency for implementing surveillance, vector control, and strengthened biosecurity measures to safeguard avian populations in ex situ conservation programmes.