For the first time, scientists were able to confirm that Plasmodium, the parasite that causes malaria, exists and is transmissible in the frigid temperatures of the Alaskan arctic, according to a study published in PLoS last week.
A group of California and Alaska-based researchers collaborated on this study to determine how changes in environmental conditions affect the distribution of Plasmodium in the North American arctic. They discovered that one type of malaria parasite- Plasmodium Circumflexum (P43)- is able to complete its transmission cycle in much higher altitudes than previously thought. The parasite P43 causes avian malaria and is not a threat to humans. Nevertheless, these findings may help researchers and scientists better understand how human malaria is affected by the global climate crisis.
The parasite was discovered in resident and migratory birds in two of the three research sites, in Anchorage and Fairbanks. With the help of satellite imagery and classification models, the researchers were able to create a predictive map of Plasmodium transmission. The results showed that by 2080, the malaria parasite will have spread past Coldfoot, the northernmost research site, which is approximately 600 miles north of Anchorage. This could have a devastating impact on both resident and migratory bird species in the area.
Plasmodium Circumflexum is a generalist parasite, meaning it can thrive in a wide variety of environmental conditions. Unfortunately, generalist parasites are most able to adapt to new hosts and areas, making widespread transmission a potential concern. This worry is further exacerbated by the complete immunological naivety of arctic bird species. Most, possibly all, resident arctic bird populations have never encountered avian malaria, and therefore have no resistance to the disease. This makes them exceedingly vulnerable to infection.
“Now that Alaska has been identified as an area with suitable climatic conditions for the completion of the avian malaria transmission cycle, a long-term monitoring of Plasmodium occurrence as it relates to climate variation in this region is essential,” remark study authors Claire Loiseau, et al. This will include monitoring mosquito species to determine the actual vector of parasite P43. Preparations for this are already underway, as over 6,000 captured mosquitos are currently being investigated at a California laboratory.
It is difficult to assess the impact of climate change on human malaria transmission and distribution due to the many conflicting socioeconomic variables, such as poverty or access to services, that affect the pandemic. This study therefore serves as an integral first step towards creating similar predictive models for other types of malaria, potentially human malaria, in the future.