Scientists race to find genetic clues as malaria decimates rare Hawaiian honeycreepers

In Animals, Earth Science, Research News, Science & Nature / 9 January 2018 / 0 comments

By Michelle Z. Donahue

As average annual temperatures increase, mosquitoes have also been on the move—up the mountains of the Hawaiian islands. Once a refuge for native birds susceptible to mosquito-transmitted avian malaria, altitude no longer guarantees safety from a disease that can kill them in a matter of days.

The question of what may happen to these endangered birds as their environments continue to shift due to climate change is key to their ultimate survival. The answer may lie in their genes.

Over the next several years, bird, malaria and mosquito experts from Rutgers University, the Smithsonian, and other research organizations will be working to sequence genomes of the amakihi, a species of Hawaiian honeycreeper with populations that appear to be developing resistance or tolerance to avian malaria. They’ll also be sequencing genomes of the southern house mosquito (Culex quinquefasciatus) and the malaria parasite it carries, Plasmodium relictum, both invasive to Hawaii.

The National Science Foundation awarded the team a four-year, $2.5 million grant to conduct the work.

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Malaria family tree has bird roots

Date:March 24, 2016

Source:Cornell University

Extensive testing of malarial DNA found in birds, bats and other small mammals from five East African countries revealed that malaria has its roots in bird hosts. It then spread from birds to bats and on to other mammals.

A study published this week in the journal Molecular Phylogenetics and Evolution reveals a new hypothesis on the evolution of hundreds of species of malaria -- including the form that is deadly to humans.

Extensive testing of malarial DNA found in birds, bats and other small mammals from five East African countries revealed that malaria has its roots in bird hosts. It then spread from birds to bats and on to other mammals.

"We can't begin to understand how malaria spread to humans until we understand its evolutionary history," said lead author Holly Lutz, a doctoral candidate in the fields of Ecology and Evolutionary Biology and Population Medicine and Diagnostic Sciences at Cornell University. "In learning about its past, we may be better able to understand the effects it has on us."

Lutz and her colleagues took blood samples from hundreds of East African birds, bats, and other small mammals and screened the blood for the parasites. When they found malaria, they took samples of the parasites' DNA and sequenced it to identify mutations in the genetic code. From there, Lutz determined how different malaria species are related based on differences in their genetic code. Having large sample sizes from many species was key.

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Birds catching malaria in Alaska

Birds can catch malaria at least as far north as Fairbanks, Alaska, a new study confirms. And at the rate climate is expected to change, the risk zone for avian malaria might stretch beyond the Arctic Circle by 2080.

Throughout much of continental North America, malaria-causing Plasmodium parasites have been hitchhiking inside mosquitoes from bird to bird for eons. But many long-exposed bird species don’t get particularly sick because they’ve developed some degree of tolerance over time. What’s worrisome about the northward creep of malaria risk is that parasites might reach bird populations that haven’t been exposed, explains disease ecologist Ravinder Sehgal of San Francisco State University.

People aren’t at risk: The 80-plus species of Plasmodium that cause avian malaria don’t infect humans, nor do the five that cause human malaria affect birds. Climate may also change transmission risk for the human form of the disease, but with its own pattern.

Genuine made-in-Alaska malaria transmission showed up in several Fairbanks birds, Sehgal and his colleagues report September 19 in PLOS ONE. The researchers could tell the parasites had attacked locally because one bird, an infected myrtle warbler, was too young to have migrated yet and the remainder, all black-capped chickadees, stay in Alaska year-round.

Read on:  http://www.sciencenews.org/view/generic/id/345337/title/Birds_catching_malaria_in_Alaska