Climate Change Promotes the Emergence of Serious Disease Outbreaks of Filarioid Nematodes

Abstract

Filarioid parasites represent major health hazards with important medical, veterinary, and economic implications, and considerable potential to affect the everyday lives of tens of millions of people globally (World Health Organization, 2007). Scenarios for climate change vary latitudinally and regionally and involve direct and indirect linkages for increasing temperature and the dissemination, amplification, and invasiveness of vector-borne parasites. High latitude regions are especially influenced by global climate change and thus may be prone to altered associations and dynamics for complex host-pathogen assemblages and emergence of disease with cascading effects on ecosystem structure. Although the potential for substantial ecological perturbation has been identified, few empirical observations have emanated from systems across the Holarctic. Coincidental with decades of warming, and anomalies of high temperature and humidity in the sub-Arctic region of Fennoscandia, the mosquito-borne filarioid nematode Setaria tundra is now associated with emerging epidemic disease resulting in substantial morbidity and mortality for reindeer and moose. We describe a host-parasite system that involves reindeer, arthropods, and nematodes, which may contribute as a factor to ongoing declines documented for this ungulate species across northern ecosystems. We demonstrate that mean summer temperatures exceeding 14°C drive the emergence of disease due to S. tundra. An association between climate and emergence of filarioid parasites is a challenge to ecosystem services with direct effects on public health, sustainability of free-ranging and domestic ungulates, and ultimately food security for subsistence cultures at high latitudes.

Standardized monitoring of Rangifer health during International Polar Year

“…Emerging diseases are of increasing global importance, and are also of considerable concern for northern ungulates (Kuiken et al, 2003;Kutz et al, 2004;Laaksonen et al, 2010). Northward range expansion of domestic and wild animals, together with various pathogen vectors, may allow introduction of new pathogens into Rangifer range.…”

“…Northward range expansion of domestic and wild animals, together with various pathogen vectors, may allow introduction of new pathogens into Rangifer range. Concurrently, a warming climate is removing some of the environmental constraints on existing arctic pathogens, resulting in range expansion of pathogens and emergence of disease (Hoberg et al, 2008;Kutz et al, 2009;Laaksonen et al, 2010). Establishing comprehensive baselines for pathogen biodiversity and abundance is necessary if we are to detect emergence of new pathogens and disease syndromes.…”

On Being A Bird in the Arctic.

“…Studies of ptarmigan parasite loads have revealed a wide variety of blood parasites, including those transferred by mosquito vectors (Holmstad et al 2003), the prevalence of which is expected to increase with warming. There is evidence even now of increased outbreaks of mosquito-borne filaroid nematodes among ungulates in subarctic Fennoscandia, and with apparent demographic consequences (Laaksonen et al 2010). Mosquito habitats may multiply with increased rain and melting permafrost, and the lengthening summers may allow greater development and plasticity within the life cycles of many parasites and pathogens, promoting their prevalence, transmission, and the diversity and longevity of their vectors (see Laaksonen et al 2010).…”

“…There is evidence even now of increased outbreaks of mosquito-borne filaroid nematodes among ungulates in subarctic Fennoscandia, and with apparent demographic consequences (Laaksonen et al 2010). Mosquito habitats may multiply with increased rain and melting permafrost, and the lengthening summers may allow greater development and plasticity within the life cycles of many parasites and pathogens, promoting their prevalence, transmission, and the diversity and longevity of their vectors (see Laaksonen et al 2010). Bennett et al (1992) reported that blood parasites were "…virtually absent in bird species nesting in the open tundra," with the inference that vectors were lacking, and one wonders what their predicted arrival may portend for avian populations.…”

Culex pipiens as a potential vector for transmission of Dirofilaria immitis and other unclassified Filarioidea in Southwest Spain

“…Filarioid nematode parasites affect millions of people and animals worldwide, and represent a major health hazard with significant economic implications (Laaksonen et al, 2010). Canine dirofilariosis is a major veterinary health problem in tropical, subtropical and temperate regions of the world (Simón et al, 2012), with at least 70 species of mosquitoes being considered as potential vectors .…”