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February 24, 2024

Animal Antics: Lemurs endangered by aggressive parasites

By MELANIE HSU | January 31, 2013

Don’t you just hate it when you hear the distinctive buzzing sound of a mosquito right as you’re about to fall asleep? As annoying as your situation seems, the climate change-related challenges that many species of animals have to deal with are far, far worse.

As temperatures continue to heat up, parasites such as mosquitoes will become more aggressive in their efforts to colonize new land, becoming pests of many other species that inhabit the land. Studies such as the one published on Dengue fever last July suggest that the mosquitoes’ plan of attack is not strictly restricted from higher latitudes and altitudes.

A recent study on lemurs, a group of primates endemic to Madagascar (and also featured in the eponymous, animated movie), examined the effects of rising temperatures and shifting rainfall patterns on the spread of lemur parasites.

By analyzing data on six parasite species, gathered from ongoing surveys of lemur health, as well as data about Madagascar’s environment as a whole,  a research team from Duke University created probability maps of lemur parasite distributions on the island.

By combining this information with climate projections for the year 2080, the team was able to make estimates of what parasite distributions might look like in the near future. Lead author Meredith Barrett, who conducted the study during her graduate years at Duke, says that these models can potentially be used to protect both lemur survival and human health by assessing where the risk of lemur-human disease transmission may be highest.

But these poor lemurs have more than parasites to be concerned about. As of now, more than 90 percent of the lemurs’ forest habitat has been devastated by logging, farming, and grazing. Lemur hunting (which is of course illegal, so don’t think about putting eating bushmeat as one of your ultimate life goals) is also a rampant issue.

As hospitable land becomes increasingly scarce for these primates, it is crucial that we find a way to keep these lemurs healthy. For one, the weather is not going to be in their favor. The models predict that annual temperatures in Madagascar will rise by 1.1 to 2.6 degrees Celsius by 2080. In addition, rainfall, drought and cyclone patterns are bound to change.

In a study published in this month’s issue of the journal Biological Conservation, Barrett and her colleagues examined the implications of these changes for lemur health by studying the cues of their parasites.

The assortment they tested was quite appetizing: a total of six species of mites, ticks, and intestinal worms that are commonly found in lemur fur and feces.

You may have heard of some of these lovely little creatures – pinworms, whipworms, and tapeworms are known to cause diarrhea, dehydration, and weight loss in humans. Do not ever use them as a diet tool – yes, some people actually try. Others, such as mites and ticks, are capable of transmitting diseases such as plague, typhus or scabies.

When the researchers compared their present-day maps with their predicted future parasite distributions, they found that the lemur parasites could expand their already formidable territory by as much as 60 percent. For instance, whipworms, which are currently confined to the island’s northern and western coasts, may make a successful migration to the southeastern coast as well.

Anne Yoder, senior author of the study and Director of the Duke Lemur Center, says that the research is especially important since the International Union for the Conservation of Nature (IUCN) has identified lemurs as the most endangered mammals on earth.

As the weather warms up, parasites could – yes, you guessed it right – grow and reproduce at faster rates, or move to higher latitudes and elevations that were once inhospitable to their ranks. As the parasites conquer more and more land, their diseases will also show up in new places. If these parasites were to infect lemur populations that have never encountered them before, and thus lack any defenses against them, the consequences will be disastrous.

Of course, the changing parasite distributions could affect humans as well. As the population growth forces more and more people (and their livestock) to move into previously uninhabited areas, the chances of sharing diseases with wildlife become increasingly high.

Hopefully, the results of this research can help people to neutralize disease hotspots before the parasites make their move.

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