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New species of avian blood parasites related to malaria discovered
Dr. Ravinder Sehgal PhD, Department of Biology - San Francisco State University |
Avian malaria is a common parasite found throughout the world. Aside from polar species such as penguins, gyr falcons and snowy owls, it does not kill birds. It can, however, affect their reproductive abilities. Studies have shown that these blood parasites can negatively affect clutch size, hatching and fledging success. Avian malaria is a caused by species of the genus Plasmodium , but there are other closely related parasites that have similar life cycles. Haemoproteus is a blood parasite that looks almost identical to Plasmodium when it is found in red blood cells. Leucocytozoon is somewhat different in that it can enter both red and white blood cells. Mosquitoes spread Plasmodium , biting midges spread Haemoproteus and blackflies spread Leucocytozoon. All three types of these parasites are commonly found in birds. |
 Since 2002, Dr. Ravinder Sehgal has been studying the blood parasites from samples collected at Lindsay Wildlife Museum, Golden Gate Raptor Observatory and the University of California Davis Raptor Center. A drop of blood from each bird is put on a microscope slide for visual inspection and another drop is collected in a special buffer for DNA studies. The slides are examined to determine the prevalence of these parasites in wild birds. Of 591 birds tested so far, 177 (29.9%) were infected with Leucocytozoon. Of 273 birds tested, nearly 50%, 134 had either Plasmodium or Haemoproteus . Cooper's hawks had the highest infection rates. |
 A second study is being published in the Journal of Parasitology. Based on traditional taxonomy, Leucocytozoon toddi is the sole valid species of Leucocytozoon parasites in diurnal raptors worldwide. However, DNA sequence analyses show that red-tailed hawks and Cooper's hawks have very different strains of this parasite . Even though the parasites have the exact same morphology in the two hawk species, their DNA sequences are very different. Moreover, Leucocytozoon from accipiter species in Europe resemble the parasites found in Cooper's hawks from California more closely than the California Cooper's hawk parasites resemble those found in California red-tailed hawks. Similarly, a Leucocytozoon strain from a common buzzard from Kazakhstan resembled the strain found in red-tailed hawks in California. This is an example of cryptic speciation-two or more species that look exactly the same but are actually quite different. The big question now is how do red-tailed hawks and Cooper's hawks that live so near to each other get such different strains of parasites? Either the insects bite preferentially or the birds have immunity against certain strains but not others. Much more research needs to be done on these subjects. |
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