Tropical Health Matters

Kenya is facing at least two major and seemingly opposing changes in its malaria epidemiological profile.  SciDev.net reports on an article from The Lancet that confirms, “An analysis of data collected over 18 years from malaria-infected children at Kilifi District Hospital, on Kenya’s Indian Ocean coast, found that paediatric admissions for malaria had fallen by 75 per cent over a period of just five years.”

At the same time, “In recent years malaria has also appeared in the highland areas where it was previously unheard of,” according to Inter Press Service (Johannesburg).  Keeping pace with these changes is essential if the national malaria control services and its malaria donor partners are to provide appropriate interventions for each part of the country.

In the highlands where people are less used to malaria, Sumba and colleagues found that. “A significant proportion of this highland population chooses local shops for initial malaria treatment and receives inappropriate medication at these local shops, resulting in delay of effective treatment.”

Because highland residents, for example those in Kibera, Nairobi, travel back to their home villages in malaria endemic areas, they bring the parasites back. With the potential of global warming making the highlands more favorable to malaria transmitting mosquitoes, the highlands will face increasing risk, according to an IRIN news release. Furthermore, “As 20 percent of Kenya’s population — eight million people — living in the highland areas are now exposed to malaria, new plans for preparing and responding to an epidemic are needed” (Inter Press Service News).

In The Lancet article O’Meara and colleagues believe that the reduction in transmission in coastal Kilifi is multi-factorial and could be related to bednet use and changes in malaria drug policy among others. They conclude that, “Our results are consistent with comparisons between multiple sites and provide further evidence that reduction of trans mission leads to a change in pattern of severe disease but might not lead to immediate reductions in disease burden.” This means that …

Emphasis on use of insecticide-treated bednets, early treatment, and other control measures must be increased to maintain reductions in disease burden and prevent a potential resurgence of malaria in a population with far less immunity than before.

The experience in Kenya shows that changing climatic conditions and increasing effectiveness of malaria control interventions may in the short run put more people at risk of severe malaria due to reduced immunity levels.  The need for sustaining efforts in some parts of the country and focusing new interventions on others makes the elimination of malaria a challenging and ever shifting target.

Malaria “vectorial capacity was estimated to be 77.7% higher in the deforested site than in the forested site” in western Kenya according to a new study by Afrane and colleagues. Deforestation created micro-climates and micro-habitats. They concluded that “deforestation in the western Kenyan highlands could potentially increase malaria risk,” and unfortunately, “In African highlands where temperature is an important driving factor for malaria and the human population generally has little functional immunity.”

Generally, “Kenya’s forests are rapidly declining due to pressure from increased population and other land uses,” as explained by the World Rainforest Movement (WFM). The process has been long standing from including early establishment of large agricultural plantations in the last Century to continued agricultural expansion based on population growth and logging. WFM advocates for community involvement in forest conservation.

Kenya is making progress on reducing malaria deaths through successful LLIN and treatment efforts, but this may be offset if communities do not see the connection between malaria and their environment.  Intersectoral collaboration in malaria control is crucial so that gains in malaria intervention coverage are not counteracted through expanding endemic areas.

Malaria is a disease with strong links to the environment. Here are a few thoughts on malaria in observance of Earth Day.

• Washing Long Lasting Insecticide-treated Nets infrequently will not only preserve their effectiveness longer but might save water
• Integrating agriculture – e.g. coffee production – into existing forest ecology saves trees, whose clearing would have opened more mosquito breeding sites
• Appropriate and safe use of insecticides during indoor residual spraying can prevent environmental contamination

People alter the environment in many ways that make mosquito breeding possible and in the process create other environmental problems. We may thereby make the environment less economically viable – as people lose income they are less able to afford malaria treatment and preventive interventions or buy or build housing that protects them from disease. We need to look beyond medicines and nets and think about the broader social, economic and environmental factors that contribute to the spread or control of malaria.

Please feel free to add your own ideas and help celebrate Earth Day.

The Cape Times has issues a warning that greatr than normal malaria transmission is expected during the current rainy season in southern Africa. They quote a WHO official as syaing, “Malaria transmission from November 2007 to May 2008 is expected to be above normal in most parts of southern Africa. In East Africa, October to May is an important part of the rainy season, when malaria transmission and epidemics can occur. In southern Africa, the heavy rains and likelihood of flooding in certain areas from December may lead to an increase in malaria transmission.” This prediction links with US Weather Service reports for early December that state, “In southern Africa, consistent with the current moderate La Nina episode, rainfall was overall above average across much of southern Africa.”

Jones et al., (2007) tested a model for understanding forecasting malaria in the highlands of Tanzania, Such highland areas, like much of southern Africa are subject to epidemics as opposed to the year round transmission found in the lowlands of much of Africa. They addressed the issue of Malaria Early Warning Systems (MEWS) based on climate variations that have been proposed to warn ministries of health of the potential of increased risk of malaria epidemics and drew attention to the The El Niño Southern Oscillation cycle. this builds on suggestions for creating such a system by Thomson and Connor (2001).

Jones et al., found that “malaria incidence is positively correlated with rainfall during the first season (Oct-Mar). For the second season (Apr-Sep), high malaria incidence was associated with increased rainfall, but also with high maximum temperature during the first rainy season.” Chaves and Pascual (2007) built on the malaria early warning experience to propose and discuss early warning systems for other neglected tropical diseases. They concluded that, “EWS are a feasible ecological application for neglected tropical diseases,” and recommended that “Forecasts can be useful in planning services for the populations affected, allowing estimates of approximate number of hospital beds, vaccine shots, drug doses and vector control measures.”

The increasing ability to understand weather and climate and their effects on malaria, especially in epidemic regions of the world is extremely helpful for planning timely deployment of malaria treatment and prevention interventions. This presents a big challenge to countries dependent on large scale donor project funds, which are not always dispersed in a timely manner or on a regular schedule and are thus, not always in tune with general national health and development planning cycles.

Malaria control activities need to be planned with specific local conditions in mind. This is the lesson derived from three articles which appear in the January 2008 issue of Acta Tropica.

Reporting from Burkina Faso Ouedraogo et al. observed that, “The gametocyte prevalence was significantly higher at the start and peak of the wet season compared to the dry season when corrected for asexual parasite density and age.” In fact they estimated only one infective mosquito bite a month during the dry season. While malaria control programs must clearly have their major interventions in place before the rainy season, they should also educate people to be on their guard during the dry season when people traditionally slack off on ITN use because of heat.

The man-made environment was the focus of concern for malaria transmission in western Kenya. Howard and Omlin went searching for fish ponds and found that 29% of 261 in Kisi Central District of Nyanza Province had been abandoned. Without the fish these a unused ponds became better mosquito breeding sites. The link with economic development was important since access to markets and agricultural extension services may influence whether ponds are abandoned or stocked. Thus, sustaining efforts to improve economic development through aquaculture may help prevent mosquito breeding.

Meissner et al., looked at another geo-environmental concern, variations in chloroquine resistance in urban and rural areas of Burkina Faso. They propose that higher drug pressure in urban areas may explain greater chloroquine resistance in urban communities. This has implications for phasing in changes of national malaria drug policies and well as targeting health education about malaria drug regimen adherence.

These three studies show that one size does not fit all communities when it comes to malaria control. The economic, ecological and epidemiological characteristics of each location should be considered for optimal program implementation.

We can include malaria among the various environmental problems created when humans destroy forests. Yesterday’s Guardian International looked at the problem in the Peruvian Amazon and reported that, “Climate change and deforestation are behind the return of malaria in the Peruvian Amazon. Off-season rain is altering the pattern of mosquito development, leaving puddles containing the lethal larvae in areas where malaria had been nonexistent.” Unfortunately, this forces “the mosquito to move to new areas and spreading the disease to places where people are not aware of the disease, where villagers lack the means to get hold of mosquito nets and preventive medicines, and where health authorities have no presence.”

Similarly, Afrane et al., reported that, “Significant increases in net reproductive rate and intrinsic growth rate for mosquitoes in the deforested area suggest that deforestation enhances mosquito reproductive fitness, increasing mosquito population growth potential in the western Kenya highlands.”

Yasuoka and Levins have reviewed “60 examples of changes in anopheline ecology and malaria incidence as a consequence of deforestation and agricultural development.” They found that, “sun preference was significantly associated with an increase in (anopheline) density,” although they did insert the caveat that the changes are complex and not necessarily linked directly with increased malaria incidence. They conclude that, “Because deforestation is a process that cannot be readily controlled for a variety of political and economic reasons, investigations and assessments of possible impacts of future deforestation will be crucial to minimize the ecological degradation caused by human activities and to prevent epidemics of malaria and other vector-borne diseases.

Another challenge of deforestation to malaria control is loss of plants that could provide new treatments for malaria and other diseases. Kayode demonstrates in Ekiti State, Nigeria how botanicals used by local populations for treating malaria are becoming rarer. The problem arises because of a land tenure system that pushes the boundaries of farms into the forests.

As if there were not already enough competition for scarce malaria control funding, such changes in climate and mosquito breeding can make the problem worse. In looking at the economic burden of malaria we talked about the need to integrate malaria control and development planning. Now we can see that environmental management must also be a strong part of that picture.

The World Development Report 2008: Agriculture for Development. points out starkly that agriculture has been neglected. Evidence exists that rural poverty has actually increased in Sub-Saharan Africa and South Asia, two areas of high malaria endemicity. Therefore the World Bank calls for greater investment in agriculture in developing countries. According to

Jaques Diouf in the International Herald Tribune, rising agricultural commodity prices, climate related disasters, and population increase are among factors threatening food security in the developing world. “World Bank studies show that a 1 percent price rise for staple food products leads to a drop of around 0.5 percent in calorie intake for the world’s poorest.” At the same time Diouf sees opportunities for African agricultural development if past neglect cited in the World Development Report is addressed. One needs to throw malaria into this equation.

The World Development Report identifies several ways in which malaria affects agriculture and agriculture affects malaria. Production systems, particularly irrigation and micro dams facilitate mosquito breeding. Generally the siting of villages and farms near water sources increases the likelihood of malaria, and malaria in turn is a major drain on agricultural production. The neglect of agriculture and the farming population over the years has rendered them less able to purchase or access malaria prevention and treatment services.

On the other hand some practices like keeping livestock near the house may deflect mosquitoes from humans. Even better, the Report identified that improved income from agricultural investments actually makes it possible for people to buy ITNs and obtain treatment in a timely manner. The key lesson from the report is that rural development – both in terms of health and agriculture – must be planned together for optimal benefits.

A recent WHO publication, Preventing Disease through Health Environments, addresses environmental factors responsible for malaria spread and control. Malaria contributed 10% to the environmental burden of disease for children aged 0-14 years worldwide. Specifically, “An estimated 42% of the global malaria burden, or half a million deaths annually, could be prevented by environmental management.” According to the document, There are three main approaches to the environmental management of malaria:

• Modify the environment. This approach aims to permanently change land, water or vegetation conditions, so as to reduce vector habitats.
• Manipulate the environment. This approach temporarily produces unfavourable conditions for vector propagation and therefore needs to be repeated.
• Modify or manipulate human habitation or behaviour. This approach aims to reduce contact between humans and vectors

Although some elements of individual and household behavior are involved in environmental control, it would be be an exercise in victim blaming to assume that individuals and households can take the main responsibility for taking environment measures. Water supply, drainage, road construction, river and stream control and other environmental measures are the responsibility of institutions and governments. Unfortunately such infrastructural improvements are costly, and one does not see them addressed in major malaria control programs like GFATM and PMI.

The World Bank has noted that, “Malaria affects millions in the East Asia and Pacific (EAP) region and impedes economic development, particularly affecting the rural poor. In the early 1900s malaria was controlled in many parts of the region using environmental management (EM) for vector control. EM is where the environment is modified or manipulated to reduce malaria transmission by attacking local vector mosquitoes and requires an understanding of the ecology of these species. Today malaria control is based on drugs and insecticides…” Because of questions of sustainability and resistance, the possibility of a return to environmental management is raised.

The World Bank’s Malaria Booster Program document does consider some elements of environmental management, but many of these fall more in line with integrated vector control measures in country examples like IRS, larviciding, and larvivorous fish. Some mention is made of filling spots of standing water. The larger infrastructural issues are not addressed. This is not to say that wider World Bank projects don’t address such issues, but what is needed is a more integrated approach that the malaria control potential of infrastructural projects is assessed and planned. Other development partners need to join in this effort.

Kenya is not only facing increased budget demands to treat malaria using the newer effective antimalarial drugs, it also must deal with expanding habitats for the malaria carrying anopheles mosquitoes.

The East African media organization reported, “The money used last year for malaria was the largest amount ever spent in one year in Kenya on a single disease other than HIV/Aids, and analysts say this reflects both the growing commitment of donors and the government to combat the country’s leading killer.” While donor support such as that from the Global Fund to Fight AIDS, TB and Malaria, can make child doses of Coartem available to the country at cost – about one US dollar – the country must cope with market pricing to meet its total malaria drug needs. This may range upwards to $US 8 per treatment for the consumer. If countries do not forecast and fund their total antimalarial drug needs for both children and adults, cheaper medicines from donor funds may be misused for adult clients who have malaria.
The article also implied that countries may feel resentment because they perceive that that WHO and other donors have forced their hand in adopting new drug policies that favor Coartem among other combination therapies.  Apparently the Pharmaceutical Society of Kenya (PSK) protested that the drug was too expensive. The PSK was worried that this decision to promote Coartem could not be sustained when donor funds wound down.  If countries decide to return to cheaper but less effective alternatives, the small headway made in recent years will be lost. Clearly this should be a wakeup call to donors and the pharmaceutical industry to find cheaper AND effective alternatives.

If the $US 58 price tag for antimalarials in one year was not enough of a challenge, Kenya is also faced with expanding mosquito habitats.  According to The Standard “The discovery of malaria-causing mosquito (Anopheles gambiae) in the Central highlands may have been a surprise to many, but not to climate change experts.” People living in these new malaria territories do not have the acquired immunity that those in endemic areas have, and hence the impact will be great.  While Kenya itself cannot control global climate change, being the home of the UN Environmental Agency, it should be a major advocate for encouraging global cooperation on the issue. In the meantime Kenya will have to budget even more scarce funds for malaria drugs, insecticide treated nets and IRS.

Finally, a third challenge is program management. Although one can empathize about the dilemmas facing Kenya, one needs to draw attention to the fact that the Global Fund does have concerns about how Kenya is managing the support it is receiving to provice malaria treatment. According to the Round 2 Malaria Grant Score Card (2005) which states: “The Program has failed to meet targets inseveral important service delivery areas (SDAs) including distributionof insecticide-treatednets (ITNs) (0% of target) and no data is available for number of people receiving treatment for Malaria, pregnant women receiving IPT (Intermittent Preventive treatment) or Case fatality rate.” the progress report of November 2006 shows some progress on IPT, but not nets and treatments received.

A concerted donor-country effort is needed to meet these triple challenges in a timely manner.

The issue of DDT for malaria control continues to raise emotions. Even though the World Health Organization has endorsed the use of DDT for indoor residual spraying (IRS), people make emotional claims that the banning of DDT has causes millions of deaths, because of political wrangling over its safety. A common response to the situation is to blame Rachel Carson.

The WHO position paper on IRS traces the history of its use in malaria control dating back to the 1950s, a time of optimism for eradicating malaria. While acknowledging that changing opinion about DDT safety was involved in its discontinued use, the position paper points out other serious constraints including “lack of government commitment and financing to sus­tain these efforts over the long term and to concerns about insecticide re­sistance and community acceptance.” A major reason why malaria eradication efforts of the 1950s and 1960 failed in Africa was the lack of health system infrastructure to maintain continued IRS.

The early success of IRS was not just a matter of health infrastructure, but also of epidemiology. Greater success was recorded in areas where malaria was seasonal/epidemic – areas where IRS did not have to be maintained year round.

Issues of epidemiology and entomology, not emotion are leading groups like the Malaria Consortium to encourage dialogue on appropriate use of IRS, especially in highly endemic areas with year round transmission. In particular, Kolaczinski et al. note “In high transmission settings, IRS must be implemented indefinitely and at high quality to achieve control. As current infrastructure limitations and unpredictable funding make this unlikely, each country must carefully consider the role of IRS.” In short each country must examine its own financial and epidemiological situation and make a rational choice. A combination of strategies, including ITNs, is available as no one intervention fits all circumstances. Kolaczinski and colleagues also point to the need for better costing data to aid national malaria programs in making such hard decisions.

There are donors who can help make the financial decisions easier in the short run. PMI is pledging to make IRS available in all 15 of its countries in an appropriate manner based on “environmental assessments.” The Global Fund also acknowledges the use of IRS. The GFATM malaria grant to Liberia is an example of a grant proposal that includes IRS, and IRS is being implemented in Yemen. Now that IRS has been added to the current arsenal of anti-malaria weapons, it is time to stop complaining and start fundraising to guarantee adequate supplies as well as well trained and equipped malaria control staff who will apply IRS in a safe and epidemiologically sound manner.