Roundworm infection linked to deforestation, say researchers
Recent findings published in the current issue of the Journal of Parasitology examine the ways in which land development could affect the prevalence of a parasitic roundworm in mice.
Researchers studied the parasite, Baylisascaris procyonis, to determine whether animals living near areas where land was being developed showed a pattern of high infection rates.
According to the report, B. procyonis is usually found in raccoons but also infects small rodents when they eat undigested seeds, such as corn, contained in raccoon scat.
Humans can become infected with the parasite when the roundworm's eggs are accidentally ingested - for example when children put dirt into their mouths - according to authors of the report.
While human infections are rare, scientists emphasise the importance of furthering understanding when it comes to any parasite that can transmit from animals to humans. B. procyonis has reportedly been discovered in the US, Europe and Japan, and is believed to have infected animals in south America.
The recent study involved trapping and testing 353 white-footed mice from 22 patches of forest in a mainly agricultural part of northern Indiana. The risk of disease, researchers say, is increased by the large numbers of raccoons and mice usually found in such areas.
Models were developed to predict how common and intense the infection is in this environment. Infection from the parasite was found in all areas they sampled, but the intensity and prevalence of disease varied widely.
Scientists found that the larger and more connected to forested areas the environment was, the less prominent the infection became.
Raccoons, according to the research report, thrive in small patches of wild land with easy access to grain fields. This means that in large forest patches, mice found fewer raccoon latrines to use as a food source, thereby lowering infection levels. In addition, researchers concluded that mice are likely to have small populations in these areas, accounting for the lower disease rates.
The study also found that the size of the forested area, particularly the length of its perimeter, could affect the prevalence of disease as well as the severity of the infection.
Researchers say that more refined results could be obtained through further research into the movements of racoons within their home range and the affect this has on the parasite's spread, as well as further research on the types of landscapes preferred by animals.
