Tropical Health Matters

Debate has gone back and forth as to whether malaria is a serious urban health problem or not. This issue itself is important to consider since the world’s population continues to urbanize, making it very necessary to understand the nature of urban health problems for better planning.

The key issue is the anopheles mosquito, which likes relatively clean collections of water, like puddles, exposed to sunlight. The crowding and pollution characteristic of urban areas does not favor anopheles mosquitoes, and yet studies continue to document some degree of malaria prevalence in urban communities of endemic countries.

Lagos, Nigeria represents anopheles scarcity. As far back as 1946 Muirhead Thomson observed an inhospitable environment for the breeding of anopheles. USAID partners revisited three neighborhoods in Lagos in 1998 and found malaria parasites in only 0.9% of over 900 children between 6 and 60 months of age. A. gambiae mosquitoes were not found in knockdown and human baiting studies, and a larval breeding density of only 0.3 was detected. The predominant mosquitoes were culex. Ironically in these neighborhoods, local shops were selling over US$ 3,000 per week in antimalarial drugs. Residents still perceived that they had ‘malaria’ and expressed similar cultural beliefs and perceptions as the outlying rural communities from where they had emigrated.

Clearly some level of malaria prevalence in the cities arises from traveling back and forth between rural and urban areas for economic and social obligations, for example the traders who travel back and forth guaranteeing food supplies for the cities. Urban health services therefore do need some stocks of antimalarial drugs to treat people coming in from the rural areas who are incubating a malaria infection.

A more complex issue is the nature and extent of urban malaria transmission. A recent study in Ghana found that malaria in urban areas displayed a heterogeneity and complexity that differed from the rural environment. Marked intra-city variation indicated the need for targeting specific areas, especially neighborhoods of the urban poor. A major contributory factor to malaria prevalence in many cities is urban agriculture, an informal economic activity of the urban poor.

Urban areas present a special challenge for ITN distribution. Epidemiological and entomological studies are recommended to map each city to determine target areas, and yet such targeting may be seen as discrimination by the general population who do not distinguish among types of mosquitoes and febrile illnesses. It may be politically necessary to provide ITNs in all poor neighborhoods regardless of mosquito ecology. In the area of treatment, health providers can be a bit more focused through using laboratory or rapid diagnostic tests to reduce inappropriate use of expensive antimalarials. As cities grow, are urban planners and health policy makers ready for the problem of urban malaria?

In a Washington Post book review, “Buyer Beware: Are we training our kids to be consumers rather than citizens?” Barry Schwart ( Sunday, April 8, 2007; Page BW08) noted that, “Viagra and Botox become readily available here while drugs to combat life-threatening malaria and diarrhea are not in developing countries.”

An opinion piece in The Nation entitled “Pigs in Space” (7 April 2007) observed that a millionaire Hungarian-American software programmer paid $20 million to be escorted to the Kazakh steppes, packed into a Russian Soyuz rocket and blasted towards the international space station. The Nation suggested that, “Simonyi might have spent his money fighting AIDS, or building housing for Hurricane Katrina survivors, or providing clean water to developing nations, or mosquito netting and medicine for malaria patients, or musical instruments for needy, photogenic, musically-gifted inner city school children or…well, depressingly, the list goes on and on.”

The Associated Press reported from the recently concluded climate change conference in Brussels that, “Two distinctly different groups, data-driven scientists and nuanced offend-no-one diplomats, collided and then converged this past week. At stake: a report on the future of the planet and the changes it faces with global warming.” The meeting reported that, “Malaria, diarrhea diseases, dengue fever, tick-borne diseases, heat-related deaths will all rise with global warming.”

In an upcoming issue of Newsweek International Jason Overdorf reports that along with global warming there is an increased movement of malaria bearing mosquitoes into highland regional of Asia, Latin America and Asia. He quotes another study that states, “temperature increases from 0.5 degrees to 3 degrees can double the population of Anopheles mosquitoes, which carry malaria.” Economic conditions that enable people in northern countries to afford window screens and air conditioning may stave off the spread of disease.

The World Bank has been operating a program and website that focuses on indigenous knowledge of communities and cultures where health and development projects take place. While this website explores obvious issues such as indigenous medicine and farming practices, it also looks at how local knowledge and practices can contribute to improving program management and evaluation.

Nearly 100 issues of IK Notes have been published since 1998.  For example, IK Notes #51 reminds us that quinine was derived from the chincona tree, and now artesunate drugs come from the Chinese herb, Artemisia annua.  This issue goes further to how the Tanga AIDS Working Group is enlisting the ready availability, knowledge and skills of indigenous healers to enhance home based care.

The economics of indigenous healing are examined in IK Notes #32. This issue notes that because of the local perception that malaria is relatively easy to diagnose, community members seek the most readily available and least expensive forms of treatment, often leading to the choice of indigenous medicine instead of going to hospital.

IK Notes #52 addresses the relation between indigenous perceptions of disease/illness and the knowledge of local plants for treatment.  A study in Ethiopia found that where there were no local equivalents of the term ‘malaria’, specific plants for treatment could not be isolated.

Mali is the focus of IK Notes #47 where a local plant has multiple uses. “Traditionally, rural women used Jatropha curcas for medicine (seeds as a laxative, latex to stop bleeding and against infections, leaves against malaria) and for soap production.”

Indigenous knowledge has been documented in the preventive realm. In IK Notes #73 focus groups in Malawi found that, “Malaria stands out as the single largest health problem in all of the study communities. A local wild shrub cited as an effective mosquito repellent, is used to varying extents among the study communities.”

Explore the IK website and think about how you can ensure that indigenous knowledge in other malaria endemic areas can be documented and put into use to save lives.

A few hours ago the Associated Press reported from a meeting in Paris that leading scientists from 113 countries agreed, that “global warming has begun, is ‘very likely’ caused by man, and will be unstoppable for centuries.”  Their 20-page report will be available soon.  “Very likely” was translated statistically as 90%. The panel of scientists was created by the United Nations in 1988 and has been reporting every 5-6 years.

Malaria as a disease is quite climate dependent.  Altitude and temperature are factors. Reports from highland areas of Africa indicate that changes in weather patterns, such as the El Niño, mean that, “these areas will experience more epidemics as a result of global warming” according to Koenraadt et al. (2006). This is supported by the Roll Back Malaria Partnership/WHO in their publication on malaria epidemics: “It is now better documented that important malaria epidemics in certain locales have been linked to El Niño/La Niña unusual events (the cyclical El Niño Southern Oscillation – ENSO phenomenon), which may lead to better prediction in terms of the magnitude of malaria epidemics and their health implications.”  For example, Ayamba et al. (2006) discussed the implications of El Niño conditions heating the ocean waters of the tropical Pacific Ocean during 2006-07 would lead to, “Increased risk for RVF (Rift Valley Fever) and malaria resulting from elevated mosquito vector populations, and cholera caused by flooding due to heavy rainfall in dry land areas.”

Patz and Olson (2006) indicate that a little temperature change can become a lot of mosquitoes: “Those who argue that we need not worry about small shifts in temperature should pause after considering the findings of Pascual et al. that a mere half-degree centigrade increase in temperature trend can translate into a 30–100% increase in mosquito abundance, in other words ‘biological amplification’ of temperature effects.”

Earlier this year, the Harben Lecture, printed simultaneously by The Lancet and Public Health, looked at the evidence for climate change induced disease pattern changes. More so, they expressed concern about the ability of malaria control programs to cope: “It is likely that additional populations put at risk by climate change will be in low-income countries, since it is generally assumed that more developed countries, which currently control malaria, will remain able to do so. Malaria in poorer countries is currently only restricted by climate factors in specific arid and highland regions. The ability of these countries to manage any climate-induced increase in malaria will depend on their capacity to develop and sustain malaria control programmes.” (Haines et al., 2006)  This is the crux of the matter – vulnerable populations are still vulnerable unless major progress is made in terms of health system reform, which in turn will be jeopardized if climate effects on agriculture and economic development also reduce the ability of countries to progress.