Malaria
Malaria and HIV co-infection is a critical public health problem that may fuel the spread of both diseases in countries where both diseases are endemic.
Malaria seems to be more common and more severe for people living with HIV (Kublin et al., 2005; Hoffman et al., 1999; Mermin et al., 2006; French et al., 2001; Francesconi et al., 2001; Grimwade et al., 2004; and Ladner et al., 2003 cited in Mermin et al., 2006). Men and women living with HIV with CD4 counts below 300 have both a higher risk of experiencing early treatment failure for malaria and a recurrence of malaria symptoms than HIV-positive people with CD4 counts over 300 or HIV-negative people (Van geertruyden et al., 2006).
Clinical malaria has also been associated with an increase in HIV viral load and a fall in CD4 cell count, potentially worsening the clinical outlook for people living with HIV. Repeated and transient increases in HIV viral load resulting from co-infection can amplify HIV prevalence, suggesting that malaria may be an important factor in the rapid spread of HIV infection in sub-Saharan Africa (Abu-Raddad et. al., 2006 cited in Sepulveda et al., 2007).
In areas where malaria occurs, malaria prevention should be part of basic HIV care (Whitworth et al., 2005 cited in Mermin et al., 2006).
Malaria and HIV Co-Infection is of Special Concern to Pregnant Women
Malaria during pregnancy can result in maternal death, anemia, miscarriage and premature birth, as well as other adverse effects for the infant. The first pregnancies are the most critical, as women develop pregnancy-specific immunity against placental parasites over successive pregnancies as a consequence of repeated exposure (Fried et al., 1998 cited in Gamble et al., 2007).
However, increasing evidence suggests that women who are living with HIV have the same low immunity to malaria in subsequent pregnancies as they do in their first pregnancy and are twice as susceptible to clinical malaria, which can increase the risk of adverse outcomes (Van Eijk et al., 2003 cited in Brentlinger et al., 2006). For example, co-infection increases women’s risk of developing severe anemia. It can also restrict fetal growth, reduce the transfer of maternal immunities to other infectious diseases from mother to child, and cause pre-term delivery and low birth weight.
There is recent evidence that shows a link between HIV and malaria co-infection in pregnant women and low birth weight newborns. At the same time, low birth weight infants have been shown to have significantly higher risks of mother-to-child transmission of HIV compared with infants of normal birth weight. However, studies evaluating the impact of HIV and malaria co-infection on mother-to-child transmission have revealed mixed results, with some showing greater risk, and others reporting no change (Ter Kuile et al, 2004; Kublin et al., 2005 cited in Brentlinger et al., 2006; Desai et al., 2007; WHO, 2005; UNICEF, 2003a; WHO, 2008c; UNICEF, 2009).
Significant gaps remain in how to treat HIV-positive women who are sick with malaria, especially during pregnancy. “Studies of the synergy or antagonism between antiretrovirals and antimalarials are …essential to ensure effective and safe malaria case management…and HIV treatment for pregnant women” (Ward et al., 2008: 141). Further evidence on malaria and pregnancy is available at: www.mip-consortium.org.
The Interactions Between HIV and Malaria Are Not Well Understood
“Although the consequences of co-infection with HIV and malaria parasites are not fully understood, available evidence suggests that the infections act synergistically and together result in worse outcomes” (Skinner-Adams et al., 2008: 264). “Despite the wide prevalence of malaria and HIV in many parts of the tropics, knowledge of how these two important diseases interact is still hampered by lack of knowledge in many key areas…drug interactions form only a very small part of the potentially massive number of ways in which HIV and malaria interact to the detriment of human health” (Khoo et al., 2005).
Countries with Unstable Rates of Malaria Transmission Require Special Attention
In areas where malaria occurs at regular intervals, those who survive repeated malarial infections acquire partial immunity by the age of five and carry it into their adult lives. Adults in areas with regular malaria usually experience mild infections. However in areas where malaria occurs at irregular rates (regions with unstable malaria transmission), immunity is not acquired and malaria can more easily result in death. Countries with high HIV prevalence and unstable malaria transmission include: Botswana, Namibia, South Africa, Swaziland and Zimbabwe (Idemyor, 2007). In a study of an area of South Africa with unstable malaria transmission, HIV-positive adults with malaria were significantly more likely to die (Grimwade et al., 2004 cited in Slutsker and Marston, 2007). “Unfortunately, the link between the current prevention and control programs for HIV is weak… All those involved in control activities for malaria and HIV… should approach the control of these two diseases in a more integrated way” (Van geertruyden and D’Alessandro, 2007: 467).
Bednets and Indoor Spraying Can Dramatically Reduce Malaria Transmission
Effective interventions exist which can dramatically reduce the prevalence and incidence of malaria among both women living with HIV and women who are HIV-negative. A critical intervention is insecticide-treated bednets (ITNs). To be effective, ITNs should be distributed to whole communities in order to achieve area-wide reductions in malaria transmission. As of 2006, the number of ITNs produced was sufficient to protect just 26% of the population at risk in Africa (WHO, 2008b). Long-lasting insecticidal nets have been developed in response to low re-treatment rates of conventional ITNs. These are pre-treated nets that require no further re-treatment during their expected lifespan of three to five years. Use of long-lasting insecticidal nets reduces both human exposure—most of the insecticide is hidden in the net and not bioavailable—and the risk of environmental contamination (Yartey, 2006).
The method and timing of providing bednets should be considered. ITNs distributed through outpatient HIV care programs can result in greater use. A rural community-based outpatient HIV care program in Uganda found that among 131 people who stated they received at least one net, 98% stated they still had the program-provided net and 91% reported having slept under the ITN the night prior to the survey and 88% reported sleeping under the ITN seven days a week (Cohee et al., 2008). However, ITNs distributed only to people living with HIV may become stigmatizing. In addition, because approximately 65% of African women do not present for antenatal care until the second or third trimester, distributing ITNs through antenatal care programs may not be effective, as malaria parasites may be well established by the time the woman presents for antenatal care (Brentlinger et al., 2006).
Indoor residual spraying is another vector control option that involves the application of a liquid insecticide. Insects absorb a lethal dose when they come in contact with the sprayed surfaces. The effectiveness of indoor residual spraying depends on coverage in the community and the level of acceptance. The World Health Organization recommends 12 insecticides for the use of indoor residual spraying, including DDT. DDT is one of the most widely used pesticides as it is the most affordable (Robson, 2009). However, resistance is developing to DDT and new pesticides are needed for indoor residual spraying (Feacham, 2009; Robson, 2009).
In addition, a review of 494 peer reviewed studies from 2005 to 2008 on the health impacts of DDT found that “…exposure to DDT and its breakdown product DDE may be associated with adverse health outcomes such as breast cancer, diabetes, decreased semen quality, spontaneous abortion and impaired neurodevelopment in children” (Eskenazi et al., 2009). A recent study of DDT and breast cancer found that pre-pubertal and pubertal years are critical periods of exposure to DDT that may result in increased risk for breast cancer, requiring longitudinal studies of many years (Cohn et al., 2007 cited in Eskanazi et al, 2009). Studies found that indoor residual spraying results in high DDT exposure in humans, including pregnant women and fetuses (Eskanazi et al., 2009). However, no data were found on use of indoor residual spraying for HIV-positive women who are at risk for malaria and on the impact of DDT on immunocompromised women. “Additional research is needed to understand the effects of DDT/E on the immune system and associated diseases, especially since DDT is used in areas where there are often high rates of HIV” (Eskanzi et al., 2009: 25). ITNs are as effective as indoor residual spraying (Yartey, 2006), as long as ITNs are used consistently and appropriately (Robson, 2009).
Intermittent Preventive Treatment (IPT) Is An Important Strategy in Reducing Malaria in Pregnant Women
A Cochrane review of six trials involving 2,495 pregnant women having their first or second babies found that antimalarial medications given routinely to women in their first or second pregnancy reduced parasite prevalence and placental malaria. The treatment also had positive effects on birth weight and possibly on perinatal death. Treatment must be balanced, however, against drug adverse effects, and against risks of the malaria parasite developing resistance to these drugs (Garner and Gülmezoglu, 2006). More research is also needed on the potential interactions of IPT and antiretroviral medications, particularly during pregnancy (Uneke and Ogbonna, 2009).