New Research
Potentially lethal parasite can be transmitted by mosquitoes
Archived article from Sep 20, 2004
By Mike Sutton
Brush, then squash. Remember those three words and that technique the next time you catch a mosquito dining on your arm or leg, and you’ll go a long way to protecting yourself from a potentially lethal parasitic microorganism that may be in the mosquito and is especially dangerous to those with weakened immune systems.
A study by Ann Cali, biology professor on the Newark campus, and others published in the “New England Journal of Medicine” in July indicates that microsporidia, a group of opportunistic single-celled microorganisms that can invade and devour virtually any kind of human cell, may have entered and broken down the muscle tissue of a Pennsylvania woman when she crushed a mosquito over the site where it had been drawing blood. The woman later died as a type of microsporidia called B. algerae, known to reside in the tissues of mosquitoes.
Cali, who serves as a consultant for the Centers for Disease Control (CDC) and the Armed Forces Institute of Pathology at Walter Reed Army Hospital, theorizes that the B. algerae in the mosquito may have been ground into the wound left by the insect’s hypodermic-like feeding tube. Mosquitoes secrete an anticoagulant to keep blood from clotting as they drink, temporarily leaving a clear passage directly into the bloodstream.
New research by Cali and one of her graduate students will be aimed at identifying how prevalent B. algerae is in mosquitoes in New Jersey through the collection and examination of specimens across the state. “Microsporidia kill people because they stay below the radar,” Cali observed.
Studies spearheaded by Cali have identified many of the dozen kinds of microsporidia now known to infect humans. About 1,500 species of microsporidia have been found infecting a wide variety of life forms. Their spores inhabit virtually every surface water source, becoming active microsporidia once they have been ingested by an animal susceptible to infection by that particular species.
Until recent research by Cali and her co-authors proved otherwise, the conventional scientific wisdom was that B. algerae could only invade cells on the surface of the human body because it couldn’t survive in the higher temperatures of deep tissue.
Several types of microsporidia can be lethal in human beings, although a healthy immune system is usually an adequate defense. Cali notes that AIDS patients, organ-transplant recipients and cancer patients undergoing chemotherapy need to take extra care to avoid ingesting microsporidial parasites. She recommends that they always boil tap water before consuming it or stick to bottled water. “Prevention is so much better than cure,” Cali said, adding that treatment for some types of microsporidia shows promise. “Whenever we start dealing with parasites in our cells, it’s very difficult to kill them without upsetting our body’s other processes.”
Cali recommends some simple, common-sense approaches to avoid mosquito bites and resultant infections in addition to her brush-then-squash technique, which moves any B. algerae in a mosquito’s body away from the vulnerable wound site. If people are concerned about spraying insect repellents containing DEET on their skin, they can wear lightweight, long-sleeved shirts and long pants, and spray the DEET on the fabric instead.
Taking garlic capsules, which cause the release of an odorless vapor through the pores that insects find unappetizing, also can be effective. Another approach involves coating exposed skin areas with a bath oil product called Skin So Soft, which has proven so effective that U.S. armed forces operating in swampy, mosquito-rich areas now routinely carry it with their other gear.
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