The Epidemiology of malaria in Burundi

Malaria, the disease

Malaria is the most prevalent mosquito-transmitted disease in the world. Each year between 300 to 500 million people are infected by this disease, and 1 to 2 million of people die from it (Meade & Earickson, 2005, p. 77). Malaria is caused by a parasite of genus Plasmodium. The four species of Plasmodium are P. falciparum, P.malariae, P.ovale and P.vivax. In Africa the predominant species of malaria parasite is P. falciparum. A person becomes infected when he is bitten by a female Anopheles mosquito which has previously been infected. Uninfected Anopheles mosquitoes become infected if they feed on an infected person. The incubation period of the parasite in the vector takes 13 days to complete at 24°C for P.falciparum. Malaria is therefore closely bound to the conditions which facilitate the survival of the mosquito such as habitat and breeding sites and which favor the life cycle of the malaria parasite by providing suitable temperatures. Researches on the epidemiology of malaria suggest that these conditions are determined by climatic and environmental factors. Malaria is a serious and often fatal disease. However, the disease is not contagious, and cannot be transmitted from person to person like the flu. The most dangerous form of malaria is caused by Plasmodium falciparum, which if it"„¢s not treated, can cause anemia, jaundice, kidney failure, seizures, coma, and death. In fact, P. falciparum kills up to 40% of the infected persons (Humphreys, 2001, p. 9). Approximately 90% of all malaria deaths in the world occur in Africa [5, 6]. Major factors that are responsible of this high mortality from malaria in Africa include poor access to health services, low quality of health services, and the increased resistance of malaria parasites to affordable first-line drugs such as chloroquine and sulphadoxinepyrimethamine [7,8]. Moreover, the elimination of malaria from most of Europe and North America and the failure of global malaria eradication programme led to a loss of interest in malaria for a period of about 25 years from the early 1970s to the late 1990s. For instance, only 3 of 1.223 new drugs developed during the period 1975-1996 were antimalarials [25]. Industry lost interest in the development of insecticides for public health use and support for research on malaria declined. Furthermore in many malaria-endemic countries, national malaria control programmes, established during the colonial period and sustained during the period when elimination of malaria was considered to be an achievable goal, collapsed [3]. Another very important factor is the suitable climate to malaria transmission.

Climatic influence

Temperature is a very important environmental factor that influences malaria transmission. Anopheles mosquitoes need temperatures between 25°C and 27°C for optimum breeding, feeding, and cellular metabolism. Likewise, warm temperatures are also crucial for the development of the Plasmodium parasite. In this case optimal temperature is be between 20°C and 30°C (Service, 2008, p. 37). The effect of an increase in temperature on the parasite is to shorten the sporogony (reproduction process) cycle and hence to accelerate transmission. Increasing temperature also increases transmission by increasing the frequency with which the vector takes blood meals, which increases the growth rate of vector populations through a shortening of the generation time. Higher temperatures reduce the longevity of adult vectors, and hence fewer of them will survive the sporogony cycle to become infective. There are thus upper and lower thresholds outside which malaria transmission is very inefficient or impossible. Below 16°C parasite development ceases. The intensity with which malaria is transmitted often depends on the minimum and maximum temperature ranges in which the vector and parasite reside.

Another factor influencing the multiplication of mosquitoes is rainfall. Mosquitoes breed in water. Therefore, right quantity of precipitation is required in order for the mosquito to complete its life-cycle. Too much, or too little rainfall have negative impact on mosquitoes population. In general, rainfall needs to be in the range of 50mm and 80mm each month to create of adequately-sized pools of standing water (Kovats et al., 2001, p. 1066). Increasing rainfall and vegetation density generally have a positive impact on malaria transmission through the provision of breeding sites and habitat for the vector. However, heavy rainfall may be harmful to mosquito and malaria production. Sometimes too much rain can reduce mosquito populations by washing away developing eggs and larvae, thus reducing the potential for a malaria transmission. Humidity is also of significant effect on the malaria transmission as it facilitates adult mosquito life spans of adequate length. If the average monthly relative humidity is below 60%, the life of the mosquito is so shortened that there is no malaria transmission (Ref see these India Pampana, 1969).

The burden of malaria in Burundi

Jefferey and Malaney:

In general, where malaria have hit most, human societies have prospered least(Ref). Studies have found that malaria and poverty are highly correlated. These studies have shown that malaria-endemic countries are not only poorer than non-malarious countries, but they also have lower rates of economic growth (Ref). Malaria may cause poverty by inhibiting economic growth; or causality may run in both directions. Undoubtedly poverty can be held responsible for some of the intense malaria transmission recorded in the poorest countries. There are at least two broad categories of mechanisms through which malaria can impose economic costs well beyond direct medical costs and foregone incomes. These include the impact of malaria on trade, tourism and foreign direct investment. The evidence suggests that malaria decreases household savings as families are forced to hire labor to compensate for days lost to morbidity39. In resource-poor countries in Africa, malaria prevention and treatment consume large proportions of health budgets, and since it poses a threat to indigenous populations as well as visitors, it acts as a deterrent to tourism and foreign investment in these countries. Malaria therefore not only affects the health status of African population, but also has far-reaching economic consequences inhibiting economic development (Wernsdorfer and Wernsdorfer 1988). Investors from non-malarious regions tend to evoid malarious regions for fear of contracting the disease. Industries such as tourism are particularly hard hit by malaria transmission. Investments in all sorts of production -? in mining, agriculture and manufacturing -? may similarly be crippled if the labor force faces a heavy disease burden, or if the burden raises the costs of attracting the needed labor to a malarious region.

In Burundi, malaria is a major public health issue with around 2.5 million clinical cases and more than 15.000 deaths each year. In late 2000, an epidemic of malaria from Plasmodium falciparum occurred in Burundi, with reported attack rates exceeding 200% and an estimated annual malaria-specific mortality of 1.6% in children under five years of age [Ref]. In 2001, Burundi was the world"„¢s most affected country(Ref). In 2002, malaria accounted for 46% of consultations in health facilities and 47% of deaths among children under five years of age (source: National Epidemiology and Statistics Service). For more than a decade, prevalence of malaria in Burundi has been increasing, for example from 548201 cases in 1991 to 3 047 319 cases in 2000(Ref). This malaria situation has been aggravated by the increasing appearance of resistance of P. falciparum to first-line (Chloroquine) and second-line (Sulfadoxine Pyrimethamine) drugs and by a particularly severe malaria epidemic at the end of 2000 and in early 2001 (Ref: Akadiri Inoussa: Malaria Control in Burundi).

Clinical manifestations

Clinical malaria manifests itself in its mild form as a febrile illness associated with other non-specific symptoms (Bruce-Chwatt 1980, ch.3). The first clinical signs will only appear after the incubation period, which varies between nine and fourteen days for falciparum malaria. Clinical diagnosis is usually confirmed by a blood test, involving microscopic evidence of parasites in the blood, or by rapid diagnostic kit (Craig and Sharp 1997). Severe life threatening malaria is usually due to P.falciparum malaria Once transmitted to humans the parasite infects the liver and red blood cells, impairing the blood flow to vital organs. Your head and body aches, you sweat, shiver and feel as if you are dying. Acute and chronic malaria infections can alter the immune system and the body"„¢s response to vaccines, and increase vulnerability to other infections.

Furthermore, chronic malaria is an important causal factor in anaemia27,43, which has been shown to have direct physical effects, lowering worker productivity and output44,45..

(Jeffrey and Malaney)

Why is Burundi one of the most affected countries by malaria.

war: Wars and social unrest further exacerbate the transmission of malaria by collapsing public health infrastructures, public works facilities, destroying countless homes, and displacing large numbers of people (Reiter, 2001. p. 150).

Most of Burundi is rural, promiscuity, bad sanitation

Most people in rural setting rely on traditional healers as their primary health care.

Misuse of the bed net (they are some times for wedding, they were targeted by rate (Ref)

Poverty: most of people are not able to pay the consultation cost (a good news is that by the time we are writing this thesis, the government of Burundi has decided to provide free care against malaria).

Poor transportation system in rural area. In most areas suffering people are curried at tens of kilometers on a traditional stretcher. This requires the cooperation of neighbors and it may take some days to gather enough people for this activity. limited transportation (such that health care workers may have difficulty distributing drugs or vaccines

Malnutrition weakening the immunology of the population: due to 15 years of war, malnutrition has increased among children especially in the displaced people,

New rice and fish pools.

Poor drainage of wastewater providing suitable breeding pools.

Insufficient health workers especially in rural area.

Suitable climatic condition for mosquito development.

Lack or insufficient lighting.

Night temperature. When the night in-house temperature is high many people prefer to spend a big part of the soiree out-of-house on open air before going to bed. Further, people don"„¢t cover themselves and there is no cooling system in the majority of houses. Most children and adult don"„¢t are barefoot, this increase the risk of biting by mosquito

Most children in some rural areas walk bare-chested until the age of five or plus, increasing the likelihood of contact with mosquito.

Drug resistance (find the reference)

Insufficient therapy, in situation of epidemic, where a lot of people are infected, people in rural area share the cure. For example a cure of quinine is 21 tablets but it may be shared by 2,3 or more persons depending on the number of infected.

Inadequate treatment and care services

In addition, some areas lack the infrastructure, facilities, and trained personnel necessary to provide and deliver even minimal levels of health services and goods.

Lack of education.48.4% of the whole population in Burundi is illiterate (, This may cause a breach of the rules of hygiene and neglecting of medical prescriptions-This has been attributed to several causes, including population movements into malarious regions, changing agricultural practices including the building of dams and irrigation schemes, deforestation, the weakening of public health systems in some poor countries, and more speculatively, long-term climate changes such as more pronounced El Niño cycles and global warming. Furthermore, resistance to drugs and insecticides used to counter this disease has been evolving in tandem with growing caseloads.

Wars and social unrest further exacerbated the transmission of malaria by collapsing public health infrastructures, public works facilities, destroying countless homes, and displacing large numbers of people (Reiter, 2001. p. 150).

Alberto et al: These populations are exposed to factors that strongly influence the origin and magnitude of malaria epidemics, such as weakened immunity of the population associated with famine and massive displacements, failures of control measures and epidemiologic disease surveillance, and unstable environmental factors such as rainfall, temperature and vegetation [3].

What can be done ( for Malaria control)?

Personal expenditures on prevention methods such as bednets or insecticides, increased funding for government control programmes, and general development such as increased urbanization can reduce malaria transmission.

Therefore, in order to decrease the extent to which humans influence the spread of mosquito-borne diseases such as malaria, there needs to be better public health awareness, as well as a stronger political will from African governments to help reduce the amount and intensity to which future anthropogenic activities will occur.

Although the last century witnessed many successful programmes at country level to eliminate the parasite, much has to be done to disease malaria burden5.

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