Screening Mosquito House Entry Points as a Potential Method for Integrated Control of Malaria

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Partial mosquito-proofing of houses with screens and ceilings has the potential to reduce indoor densities of malaria mosquitoes. We wish to measure whether it will also reduce indoor densities of vectors of neglected tropical diseases.

Methodology: The main house entry points preferred by anopheline and culicine vectors were determined through controlled experiments using specially designed experimental huts and village houses in Lupiro village, southern Tanzania. The benefit of screening different entry points (eaves, windows and doors) using PVC-coated fibre glass netting material in terms of reduced indoor densities of mosquitoes was evaluated compared to the control.

Findings: 23,027 mosquitoes were caught with CDC light traps; 77.9% (17,929) were Anopheles gambiae sensu lato, of which 66.2% were An. arabiensis and 33.8% An. gambiae sensu stricto. The remainder comprised 0.2% (50) An. funestus, 10.2% (2359) Culex spp. and 11.6% (2664) Mansonia spp. Screening eaves reduced densities of Anopheles gambiae s. l. (Relative ratio (RR) = 0.91; 95% CI = 0.84, 0.98; P = 0.01); Mansonia africana (RR = 0.43; 95% CI = 0.26, 0.76; P<0.001) and Mansonia uniformis (RR = 0.37; 95% CI = 0.25, 0.56; P<0.001) but not Culex quinquefasciatus, Cx. univittatus or Cx. theileri. Numbers of these species were reduced by screening windows and doors but this was not significant.

Significance: This study confirms that across Africa, screening eaves protects households against important mosquito vectors of filariasis, Rift Valley Fever and O’Nyong nyong as well as malaria. While full house screening is required to exclude Culex species mosquitoes, screening of eaves alone or fitting ceilings has considerable potential for integrated control of other vectors of filariasis, arbovirus and malaria.

Author Summary: Mosquito vectors that transmit filariasis and several arboviruses such as Rift Valley Fever, Chikungunya and O’Nyong nyong as well as malaria co-occur across tropical Africa. These diseases are co-endemic in most rural African countries where they are transmitted by the same mosquito vectors. The only control measure currently in widespread use is mass drug administration for filariasis. In this study, we used controlled experiments to evaluate the benefit of screening the main mosquito entry points into houses, namely, eaves, windows and doors.

This study aims to illustrate the potential of screening specific house openings with the intention of preventing endophagic mosquitoes from entering houses and thus reducing contact between humans and vectors of neglected tropical diseases. This study confirms that while full house screening is effective for reducing indoor densities of Culex spp. mosquitoes, screening of eaves alone has a great potential for integrated control of neglected tropical diseases and malaria.

Citation: Ogoma SB, Lweitoijera DW, Ngonyani H, Furer B, Russell TL, et al. (2010) Screening Mosquito House Entry Points as a Potential Method for Integrated Control of Endophagic Filariasis, Arbovirus and Malaria Vectors. PLoS Negl Trop Dis 4(8): e773. doi:10.1371/journal.pntd.0000773

Editor: Neal D. E. Alexander, London School of Hygiene and Tropical Medicine, United Kingdom

Funding: SBO was supported by a scholarship kindly provided by Valent Bioscience Corporation. This study was also supported by the Centers for Disease Control and Prevention and the United States Agency for International Development through the U.S. President’s Malaria Initiative (Award Number 621-A-00-08-0007-00), the Addessium Foundation (Reenwijk, The Netherlands) and a Research Career Development Fellowship (076806) provided to GFK by the Wellcome Trust. The funders of this study had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Copyright: © 2010 Ogoma et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

More information: Full text: Screening Mosquito House Entry Points as a Potential Method for Integrated Control of Endophagic Filariasis, Arbovirus and Malaria Vectors (PDF)

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)