Malaria is a major health problem in the world. Despite several global initiatives and intensified efforts to fight the disease in the last decade, the burden of disease remains high.1,2 In Tanzania, every year 14-18 million new malaria cases are reported, resulting in 120,000 deaths, more then half in children under five years of age.3,4
This essay is about malaria in Tanzania. The central question is: what role can local non-governmental organizations (NGO) play in the fight against malaria in Tanzania? To answer this question, information about factors contributing to the magnitude of the problem and influencing control measures is required. Using the same approach as Lalonde, the focus will be on different determinants of health.5 Environmental, economical and demographical factors will be discussed, as the impact of the Human Immunodeficiency Virus (HIV), followed by information on different control measures. Recommendations to NGOs will be made in conclusion.
To understand the different factors contributing to the malaria problem in Tanzania, some background knowledge about both malaria and Tanzania is required.
Tanzania
The United Republic of Tanzania, formed in 1964, is a very low-income country in East-Africa (Box 1). Primary Health Care (PHC) services form the basis of the structure of the national health sector and 90% of the population lives within 5km of a primary health care facility.4 With dispensaries and health centres as a basis, general hospitals, referral hospitals and specialized hospitals are higher in the pyramidal system. Many Tanzanian government functions are decentralized, with local government authorities responsible for local health services. About 40% of the health services is owned by the public sector, mainly faith-based and community-based organizations. Policy strategies and guidelines on malaria control are developed for the Ministry of Health and Social Welfare by the National Malaria Control Program (NMCP).
Box 1: Tanzania
Population of 43 million, of which 90% at risk of malaria3
Rank 151 (of 182) of Human Development Index
88.5% of population income below 1.25US$,
36% below national poverty line7
Life expectancy at birth 53 years4
Three main causes of death4
Adults: malaria, HIV/AIDS, tuberculosis
Children below 5 years: malaria, pneumonia, anaemia
Figure 1: malaria cycle9
Malaria
Malaria is a disease caused by parasites of the genus Plasmodium. Of the five species that can cause human illness, P. falciparum is the most dangerous. In the malaria cycle humans are the only host, the vector for parasite transmission are Anopheles mosquitoes (Figure 1). After being bitten by an infected mosquito symptoms can develop in a week. Clinical malaria occurs as the parasite reproduce in red blood cells. Various clinical manifestations are possible, with cerebral malaria and anaemia as the most prominent ones. Partial immunity can be acquired, though this effect is temporarily and depended upon the transmission intensity. In malaria epidemiology areas can be classified as stable and unstable, with high transmission and immunity characterizing the former.8 In Tanzania endemic areas with stable malaria are most prominent, but there are areas of unstable transmission where epidemics occur.
Search Method
A search for relevant research was conducted in Medline and Scopus.10,11 Separate searches for different determinants of health were conducted (Box 2). References and the 'related articles' function were used to identify other articles, sometimes concerning East-Africa. Reports of the Tanzanian government and inter-governmental organizations were found through their websites.
Box 2: Search Strategy [example]
malaria AND Tanzania
AND
agriculture OR "land use" OR
ecological OR environmental
Limits: English language
Excluded: not available in full-text
Figure 2: malaria map of Tanzania17
(white: no transmission, red: high transmission)
Results
Environmental factors
Tanzania is situated in the 'malaria belt'. The climate in most areas is favorable to malaria transmission (Figure 2). The most common vectors in Tanzania are A. gambiae and A. funestus, two highly anthropophilic and the most effective malaria vectors in the world.12 Temperature is a major component for the development of the parasite as well as the mosquito.12 Living nearby swamps and forests is also shown to increase the risk of malaria.12 The effects of agriculture and urbanization on malaria transmission are poorly understood.13-15 Land irrigation can increase the number of mosquitoes, but an anthropophilic vector is often replaced by a zoophilic mosquito, causing a decrease in transmission. In an area with stable transmission the effect on transmission either way will be minor. The wealth gained by irrigation schemes probably will have a bigger impact on malaria control.16
Economical factors
While acknowledging the environmental factors described above, it cannot be ignored that countries of the malaria belt are among the poorest in the world. The rise of malaria deaths from 100 to 160 per 100,000 since the late 1970s up to 1999 coincided with a drop of 40% per capita gross domestic product (GDP) in sub-Saharan Africa.18 The relation is complex and the causality probably works both ways.19 Poor households (or countries) experience a higher malaria prevalence that in turn maintains them in poverty.19,20 In a 2005 study Jowett and Miller found that 39% of all health expenditures were on malaria, 1% of the GDP. Approximately 75% is borne by households, 20% by the government and development partners contributing 5%. Individuals allocate 0.7% of their income to the disease.21
As for most communicable diseases, the vicious circle of poverty and ill health holds up for malaria as well.3
Demographical factors
Usually when calculating the costs of malaria, as described in the paragraph above, the focus is on (private or non-private) health expenditures. Often foregone income due to morbidity or mortality is taken into account extrapolating from the costs of individual episodes of illnesses. These methods do not take into account the effect of changes in behavior, whether on the microeconomic level (e.g. schooling, migration), or macroeconomic costs (e.g. impact on trade and tourism).20 The high prevalence of sickle cell disease and α-thalassemia in malaria endemic areas is a sign of the historical impact of the disease on population characteristics.22-24
HIV and Acquired Immunodeficiency Syndrome (AIDS)
Malaria and HIV highly overlap in geographical distribution. An estimated 6% of Tanzanian adults are currently infected with HIV.25 Co-infection is very common in Tanzania and understanding the possible interactions is therefore key for the control of both diseases.26 Immunodepression caused by HIV doubles the chances of severe malarial disease, especially in areas with unstable transmission.27,28 This is an obvious risk increase, but not as great as in classical opportunistic infections.29,30 A reverse relation, i.e. the impact of malaria on HIV disease progression, is not yet well established.26 Better understood are the effects of HIV status and malaria in pregnancy.31 In seronegative women in areas with stable malaria transmission, an increased malaria risk is observed only during the first pregnancy. HIV increases the risk of malaria, especially in multigravid women.32,33 This increased malaria risk is not only a danger to the mother, but also dangerous for the neonate.31,34 The effect of malaria on HIV progression and mother to child transmission of HIV is unclear.35
A conservative 2005 estimate attributed a 5% increase in malaria deaths to HIV.36
Control
With the widespread resistance to cheap antimalarials hope for an easy solution has diminished. Effective control measures, however, do exist and in the past years global commitment to fight malaria has been growing.3 Stimulated by the Roll Back Malaria Partnership there has been in an increase in funding for research and control.2 The HIV epidemic is another cause of increased availability of resources in developing countries. On the one hand there was an obvious shift of resources from malaria to HIV control. Even though malaria is the leading cause of morbidity and mortality, HIV was declared a national disaster in 2003.3 On the other hand the increased attention to health problems in poor-resource countries led to more funding specifically for malaria programs, most notably by the Global Fund to fight AIDS, tuberculosis, and malaria.
In accordance with the Roll Back Malaria Partnership strategy the NMCP has adopted four focus areas for operational strategies:6,37,38 case management, vector control, prevention of malaria in pregnancy and epidemic preparedness.
Case management
Early treatment of malaria is important, with appropriate health seeking behavior being the first step. Many factors causing delays are well recognized, such as economic restraints, failing to recognize the seriousness of the situation and seeking care in the informal sector.25,39-42 The majority of episodes of febrile illnesses are still presented in the formal and informal private sector, with a higher risk of inappropriate treatment.41,43
The latest guidelines of the World Health Organization place a higher emphasis on laboratory confirmation.37,44 Approximately 40% of fevers are due to malaria and overtreatment is dangerous and expensive, making up an estimated one-eight of malaria expenditures.43 Since 2006 the first-line therapy is artemisinin-based combination treatment (ACT). However very effective and with few side effects, the costs are 20 times higher than that of conventional therapies, putting high pressure on malaria control.
Vector control
The effectiveness of insecticide-treated bed nets (ITN) is well studied.45 The fear that use of bed nets increases mortality by lowering immunity in areas of stable transmission proved unwarranted.46 In Tanzania the objective is to have 60% of the vulnerable population (young children and pregnant women) sleeping under and ITN. A subsidy scheme for the distribution of Long Lasting Insecticidal Nets (LLIN) was started in 2008.6 Vouchers can be exchanged in designated private outlets. This public-private partnership was designed to improve coverage of services.47 In a 2007-2008 survey 38% of the mainland population owned at least one ITN, but consistent use is much lower.25
Another intervention for vector control is the use of indoor residual spraying (IRS) with insecticides to reduce mosquito densities. To complement the scaling up of ITNs, IRS was implemented in selected regions.6,25
Prevention of malaria in pregnancy
Pregnant women are more vulnerable to malaria. There is an increased risk of severe malaria and placental infection is a major cause of neonatal mortality. Intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) is effective in reducing maternal and neonatal mortality, especially in combination with the use of ITNs.48-51 IPTp is still effective with resistance to SP and HIV-infection, but in the latter case more frequent dosages are required.48,52 The major problem in implementation of IPTp is low coverage of the antenatal clinics and women presenting late in pregnancy. An estimated 57% of pregnant women in mainland Tanzania received at least one dose of IPTp, but only 30% two or more doses.25
Malaria epidemics prevention and control
Twenty-five percent of the districts in Tanzania are epidemic prone.53 A malaria warning system is in place in most of these districts. This system has to be monitored and evaluated to improve.53
Challenges in implementing control
Different obstacles have been identified that stand in the way of implementing control measures in Tanzania.3,6,53 Not surprisingly financial constraints form a major impediment.3 Another challenge is the human resource crisis in the health sector.54 Only 35% of qualified staff is available.6 Especially in remote areas incentives are too low to attract staff. The burden of HIV/AIDS exacerbates this situation.
Another problem is the weak health system, unable to deliver interventions and health care.3 Since the 1980s the national policy is to implement malaria control as part of the PHC approach.53,55 Many times malaria is given low priority, so many districts do not develop effective control programs.3 A study by Alilio showed that the weak district health system was the cause of the burden of malaria remaining high in Muheze district.56 A positive development are recent policies giving high priority to strengthen and decentralize district health services.6
Discussion
The high burden of malaria in Tanzania can be attributed to some extend to factors that are not easily controlled. Ecologic and climatic factors favor malaria transmission. A high level of poverty and the HIV-epidemic make the population extra vulnerable. This does not mean however, that control is impossible. A century ago malaria was endemic in moderate climates as well as in the tropics. The Global Malaria Eradication Campaign in the 1960s eliminated malaria was successful in many of the temperate regions. In Tanzania, this success was marred by the emergence of resistance to cheap insecticides and antimalarials, together with a general weakening of health systems.19 In these days a number of evidence-based control measures are successfully implemented in sub-Saharan Africa. The Zanzibar anti-malaria program, which comprised of free ACT and ITNs, proved very successful, causing a reduction of 90% in malaria deaths.1 These facts show that it is indeed possible to interrupt the malaria cycle when there is enough commitment. The challenge lies in implementing control measures in the entire population. Although not having reached the level of success of Zanzibar, mainland Tanzania saw a small trend in improved child health indicators over the past ten years, in which the improved prevention and treatment of malaria probably were important contributors.6 The small reduction should be seen in the context of increased HIV-related child mortality, thus can be a cause for some optimism in regard to malaria control.
Recommendation
How can NGOs help to combat malaria in Tanzania? Scaling up vector control (IRS in conjunction with increased LLIN coverage) and availability of ACT will rapidly reduce malaria transmission and these measures should be the backbone of malaria control. As explained before these clear objectives face multiple challenges. In a public-private partnership NGOs can improve the coverage of care while being in line with the national strategies. This worked well with ITN distribution and could be used in IRS as well. Furthermore NGOs can help strengthening the district health system by assisting in PHC programs. Of course the availability of control measures should be accompanied by education and information campaigns, preferable on the district level. Partnerships with NGOs can provide a more attractive working environment and draw extra healthcare workers.
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