Study Finds Bird Malaria Spreading Via Global Hotspots
BRISBANE, Australia — The answer to why bird species across the globe are suffering and dying from a type of malaria has been found through new research.
The findings of the study were published in the journal “Global Ecology and Biogeography.” It is a bimonthly peer-reviewed scientific journal that was established in 1991. It covers research in the field of macroecology.
An international team, including The University of Queensland’s Nicholas Clark, has been researching where and why the disease has been spreading so rapidly. While these strains are not infectious to humans, they are spreading quickly through global transmission hotspots.
Avian malaria is a mosquito-borne disease of birds caused by a protozoan parasite. The parasite reproduces in avian red blood cells. If the parasite load is sufficiently high, the bird loses red blood cells (anemia).
This sudden release of parasites and the loss of red cells trigger the acute phase of infection. In susceptible birds are characterized primarily by anemia, with symptoms of weakness, depression, and loss of appetite; some birds become comatose and die.
“Avian malaria now affects somewhere between 13 and 14 percent — on average — of all wild birds worldwide,” said Clark. “It’s caused by a group of blood parasites — known as haemosporidian parasites — and, much like human malaria, is transmitted via blood-feeding insects like mosquitos.”
“It can’t harm humans but is known to have significant impacts on bird populations. For example, when avian malaria was introduced into Hawaii in the late 1800s to early 1900s, it was one of the major causes of extinction of about one-third of the 55 known species of Hawaiian honeycreepers.”
He said they found that hotspots are transmitting these parasites across the world.
“The most significant hotspot was in the Sahara-Arabian region, with local hotspots in North America, Europe, and Australia, depending on different parasite variants,” Clark said.
“In fact, here in Australia, some of these blood parasites are causing high infection rates in our songbirds, including silvereyes (Zosterops lateralis) and many species of honeyeaters (the Meliphagidae family).”
The honeyeaters are a large and diverse family, Meliphagidae, of small to medium-sized birds.
The research team compiled and analyzed what is likely the most extensive data set of wild bird infections with avian malaria parasites to date, with more than 53,000 wild birds examined.
They combined infection data with remotely sensed environmental data, such as climate or forest conditions, and birdlife history information, such as body size and migration patterns, into computer models to identify which factors best described the infection risk with avian malaria parasites.
Konstans Wells, who leads the Biodiversity and Health Ecology research group at Swansea University, said predicting which conditions facilitate the infection of wild birds with avian malaria is crucial for understanding infectious disease hazards.
“Global avian malaria prevalence of 12-14 percent with local hotspots all over the world estimated from ~53000 wild birds with hierarchical modeling,” said Wells in a tweet.
“Glad to be part of the team with @AlanFecchio and many others.”
He said that since each bird species is unique in its ecological niche and is differently exposed to disease-transmitting insects during breeding and migration, infection risks are different for different bird species.
Wells said that the conditions that enable infection in different areas across the world are entirely context-dependent. For example, long-distance migrating birds were more likely to be infected in some continents but less likely in others.
“There’s no easy answer with so many factors at play, but we’re going to continue to research to find out how to best protect the world’s bird species from this deadly disease,” he said.
In 2019, the Western Pacific region had an estimated number of malaria cases amounting to around 1.7 million, as per reports by Statista.
(With inputs from ANI)
Edited by Saptak Datta and Ritaban Misra