Insecticide-Treated Mosquito Nets (ITMNs) Helps Prevent Japanese Encephalitis

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A new study reveals that using treated mosquito nets could drastically reduce the transmission of Japanese Encephalitis (JE) to humans.

The study, conducted by the Regional Medical Research Centre (RMRC), Dibrugarh, North East Region (NE), Indian Council of Medical Research and released in the March issue of the American Journal of Tropical Medicine and Hygiene, showed that the use of insecticide-treated mosquito nets (ITMNs) on humans and pigs reduced transmission of JE 72 percent in humans.

The study looked at the effectiveness of using ITMNs to protect both pig and human populations. It evaluated the efficacy of reducing the transmission of JE in areas where high virus activity has been reported. The JE virus multiplies rapidly in pigs, considered by experts to be a key element in the natural cycle of the virus and its transmission to humans.

Sharp drops in infection rates were found in three locations following the use of ITMNs. In one location, the nets were used to protect both humans and pigs which resulted in the greatest drop in infection rates (72 percent), compared with areas where treated mosquito nets protected only humans (67 percent) or pigs (56 percent).

“We are pleased that the results of this study show that ITMNs are extremely effective against JE,” said Prafulla Dutta, Scientist, RMRC, NE, “Educating people in JE-prone areas that using ITMNs will help reduce the transmission of the disease without disturbing social customs in these communities. We believe that this will, in turn, reduce mortality associated with JE while keeping communities healthy and productive, further improving the global economy.”

JE is a viral disease transmitted by mosquitoes that infects both animals and humans. It is the leading cause of viral encephalitis (infection of the brain) in Asia and is estimated to be fatal in 30 percent of cases. Death as a result of JE is particularly high among children, killing approximately 8,000 children yearly.

“Increasingly, ITMNs have been shown to be an easy-to-use and effective tool in preventing mosquito-borne diseases such as JE, lymphatic filariasis and malaria,” said Peter J. Hotez, MD, PhD, President, American Society of Tropical Medicine and Hygiene. “This simplicity of action, combined with its low cost, drives the absolute necessity for distribution of these life-saving devices on a much larger scale.”

The researchers note that insecticide components, particularly pyrethroids, are gaining importance in mosquito control because of their low toxicity towards mammals and the strong repellant impact on mosquitoes.

Source: American Society of Tropical Medicine and Hygiene (ASTMH)

The Effects of Maternal Helminth and Malaria Infections on Mother-to-Child HIV Transmission

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Objective: To investigate the effect of helminth and/or malaria infection on the risk of HIV infection in pregnant women and its transmission to their offspring.

Design: A retrospective cohort study of pregnant Kenyan women and their offspring from term, uncomplicated vaginal deliveries (n = 936) with a nested case-control study.

Methods: We determined the presence of HIV, malaria, schistosomiasis, lymphatic filariasis, and intestinal helminthes in mothers and tested for HIV antibodies in 12-24 month-old offspring of HIV-positive women. We related these findings to the presence of cord blood lymphocyte activation and cytokine production in response to helminth antigens.

Results: HIV-positive women (n = 83, 8.9% of all women tested) were 2-fold more likely to have peripheral blood and/or placental malaria (P < 0.025) and a 2.1-fold greater likelihood of lymphatic filariasis infection (P < 0.001) compared to location-and-parity matched HIV-negative women. Women with HIV and malaria tended to show an increased risk for mother-to-child-transmission (MTCT) of HIV, although this difference was not significant. MTCT of HIV, however, was significantly higher in women co-infected with one or more helminthes (48%) verses women without helminth infections (10%, P < 0.01; adjusted odds ratio, 7.3; 95% confidence interval, 2.4-33.7). This increased risk for MTCT of HIV correlated with cord blood lymphocytes production of interleukin-5/interleukin-13 in response to helminth antigens (P < 0.001).

Conclusion: Helminth co-infection is associated with increased risk for MTCT of HIV, possibly by a mechanism in which parasite antigens activates lymphocytes in utero. Treatment of helminthic infections during pregnancy may reduce the risk of MTCT of HIV.

Author Information

Gallagher, Maureena; Malhotra, Indua; Mungai, Peter La,b; Wamachi, Alex Nc; Kioko, John Mb; Ouma, John Hd; Muchiri, Ericb; King, Christopher La,e

From the aCenter for Global Health and Diseases and Center for AIDS Research, Case Western Reserve University, Cleveland, OH, USA

bDivision of Vector Borne Diseases, Nairobi, Kenya

cKenyan Medical Research Institute, Kenya

dMaseno University, Maseno, Kenya

eDepartment of Veteran’s Affairs Medical Center, Cleveland, OH, USA.

Correspondence to C. L. King, Center for Global Health and Diseases, Case Western Reserve University, 2103 Cornell Rd, WRB Rm 4132, Cleveland, OH 44106-7286, USA. Tel: +1 216 368 4817; fax: +1 216 368 4825; e-mail: christopher.king@case.edu

Citation: AIDS: Official Journal of the International AIDS Society, Nov. 4, 2005, – Volume 19 – Issue 16 – p 1849-1855

More information: Full text – The Effects of Maternal Helminth and Malaria Infections on Mother-to-Child HIV Transmission (PDF)