Host specificity of avian malaria parasites
Birds are hosts of a stunning diversity of malaria (Plasmodium) and related haemosporidan parasites (Haemoproteus and Leucocytozoon). The life cycles of these parasites are similar to human malaria parasites; the asexual replication takes place in blood or tissues of the vertebrate host whereas the sexual phase takes place in various blood-sucking insects such as mosquitoes, biting midges and blackflies. A few hundred species of bird haemosporidians have been described morphologically but the molecular analyses suggest that the true number of species probably counts in thousands. The species diversity is higher in the tropics but transmission commonly happens as far north as in Sweden. A particular concern is that a warmer climate may allow tropical parasites to expand their ranges and infect European resident species which have not encountered these parasites before, potentially posing substantial threats to these populations.
Identification of parasites and host specificity
We are primarily interested in understanding why the parasites vary in their levels of host specificity. Most of the parasites are specific to one or a few closely related host species but some are able to infect more than 100 species of birds. The parasites are identified by BarCoding (PCR and DNA sequencing of their cytochrome b gene) and the records are deposited to the on-line database MalAvi which provide information of host range and geographic distribution. Population structure, species limits and phylogeny of the parasites are studied by using transcriptome sequencing and sequence capture developed from whole genome sequencing.
Virulence and population studies
To find out the virulence of the parasites we carry out controlled infection experiments with wild birds in captivity in collaborations with researchers at the Nature Research Centre in Vilnius, Lithuania. In these studies, we can monitor the complete infection episode from the primary infection to chronic stages, measuring host responses in multiple ways including telomere loss rate. We also study the impact and dynamic of bird malaria in several species in the wild, particular in a long-term study of great reed warblers at lake Kvismaren and in a community of forest living passerine birds at lake Krankesjön.