Malaria Co-infection with Other Diseases of Global Public Health Importance

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Effects of co-infection on human health, the need for further research and steps towards integrated control

Introduction

Standley Adriko malaria Uganda 2010

Claire Standley and Moses Adriko surveying for malaria infections in a community in Uganda. Photo: Courtesy Dr Claire Standley

In large parts of the world, the Plasmodium protozoans that cause malaria co-exist alongside a number of other pathogens and parasites, many of which are also infectious to humans. One of the foremost challenges in tackling the huge burden of malaria around the world, and particularly in developing countries, is understanding the dynamics between malaria and these other infections. For example, researchers are seeking to understand the effects of co-infections on a patient’s health and well-being, while at the same time, deciphering how best to provide treatment and disease control regimes in regions with high co-infection prevalence. Moreover, of course, the effects and intricacies of co-infection may vary between regions, or between the types of infectious found alongside malaria. This blog gives a quick introduction to some of the common diseases often found alongside malaria, and especially in the developing world, where significant research resources are directed but also where treatment and control needs are greatest.

Malaria and HIV

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Soil-Transmitted Helminths and Malaria in Pregnant Women on the Thai-Burmese Border

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Background: Deworming is recommended by the WHO in girls and pregnant and lactating women to reduce anaemia in areas where hookworm and anaemia are common. There is conflicting evidence on the harm and the benefits of intestinal geohelminth infections on the incidence and severity of malaria, and consequently on the risks and benefits of deworming in malaria affected populations. We examined the association between geohelminths and malaria in pregnancy on the Thai-Burmese border.

Methodology: Routine antenatal care (ANC) included active detection of malaria (weekly blood smear) and anaemia (second weekly haematocrit) and systematic reporting of birth outcomes. In 1996 stool samples were collected in cross sectional surveys from women attending the ANCs. This was repeated in 2007 when malaria incidence had reduced considerably. The relationship between geohelminth infection and the progress and outcome of pregnancy was assessed.

Principal Findings: Stool sample examination (339 in 1996, 490 in 2007) detected a high prevalence of geohelminths 70% (578/829), including hookworm (42.8% (355)), A. lumbricoides (34.4% (285)) and T.trichuria (31.4% (250)) alone or in combination. A lower proportion of women (829) had mild (21.8% (181)) or severe (0.2% (2)) anaemia, or malaria 22.4% (186) (P.vivax monoinfection 53.3% (101/186)). A. lumbricoides infection was associated with a significantly decreased risk of malaria (any species) (AOR: 0.43, 95% CI: 0.23–0.84) and P.vivax malaria (AOR: 0.29, 95% CI: 0.11–0.79) whereas hookworm infection was associated with an increased risk of malaria (any species) (AOR: 1.66, 95% CI: 1.06–2.60) and anaemia (AOR: 2.41, 95% CI: 1.18–4.93). Hookworm was also associated with low birth weight (AOR: 1.81, 95% CI: 1.02–3.23).

Conclusions / Significance: A. lumbricoides and hookworm appear to have contrary associations with malaria in pregnancy.

Author Summary: Intestinal worms, particularly hookworm and whipworm, can cause anaemia, which is harmful for pregnant women. The WHO recommends deworming in pregnancy in areas where hookworm infections are frequent. Some studies indicate that coinfection with worms and malaria adversely affects pregnancy whereas other studies have shown that coinfection with worms might reduce the severity of malaria. On the Thai-Burmese border malaria in pregnancy has been an important cause of maternal death. We examined the relationship between intestinal helminth infections in pregnant women and their malaria risk in our antenatal care units. In total 70% of pregnant women had worm infections, mostly hookworm, but also roundworm and whipworm; hookworm was associated with mild anaemia although ova counts were not high. Women infected with hookworm had more malaria and their babies had a lower birth weight than women without hookworm. In contrast women with roundworm infections had the lowest rates of malaria in pregnancy. Deworming eliminates all worms. In this area it is unclear whether mass deworming would be beneficial.

Citation: Boel M, Carrara VI, Rijken M, Proux S, Nacher M, et al. (2010) Complex Interactions between Soil-Transmitted Helminths and Malaria in Pregnant Women on the Thai-Burmese Border. PLoS Negl Trop Dis 4(11): e887. doi:10.1371/journal.pntd.0000887

Editor: Simon Brooker, London School of Hygiene & Tropical Medicine, United Kingdom

Copyright: © 2010 Boel 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.

Funding: This study was part of the Wellcome Trust Mahidol University Oxford Tropical Medicine Research Programme funded by the Wellcome Trust of Great Britain. The funders 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.

More information: Full text: Complex Interactions between Soil-Transmitted Helminths and Malaria in Pregnant Women on the Thai-Burmese Border (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)