Malaria epidemiology and demographics: Difference between revisions
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Overview
Malaria is a vector-borne infectious disease caused by protozoan parasites. It is widespread in tropical and subtropical regions, including parts of the Americas, Asia, and Africa. Each year, it causes disease in approximately 650 million people and kills between one and three million, most of them young children in Sub-Saharan Africa. Malaria is commonly associated with poverty, but is also a cause of poverty and a major hindrance to economic development.
Distribution and impact
File:Malariageodistribution.png Malaria causes about 400–900 million cases of fever and approximately one to three million deaths annually [2] — this represents at least one death every 30 seconds. The vast majority of cases occur in children under the age of 5 years;[3] pregnant women are also especially vulnerable. Despite efforts to reduce transmission and increase treatment, there has been little change in which areas are at risk of this disease since 1992.[4] Indeed, if the prevalence of malaria stays on its present upwards course, the death rate could double in the next twenty years.[2] Precise statistics are unknown because many cases occur in rural areas where people do not have access to hospitals or the means to afford health care. Consequently, the majority of cases are undocumented.[2]
Although co-infection with HIV and malaria does cause increased mortality, this is less of a problem than with HIV/tuberculosis co-infection, due to the two diseases usually attacking different age-ranges, with malaria being most common in the young and active tuberculosis most common in the old.[5] Although HIV/malaria co-infection produces less severe symptoms than the interaction between HIV and TB, HIV and malaria do contribute to each other's spread. This effect comes from malaria increasing viral load and HIV infection increasing a person's susceptibility to malaria infection.[6]
Malaria is presently endemic in a broad band around the equator, in areas of the Americas, many parts of Asia, and much of Africa; however, it is in sub-Saharan Africa where 85– 90% of malaria fatalities occur.[7] The geographic distribution of malaria within large regions is complex, and malarial and malaria-free areas are often found close to each other.[8] In drier areas, outbreaks of malaria can be predicted with reasonable accuracy by mapping rainfall.[9] Malaria is more common in rural areas than in cities; this is in contrast to dengue fever where urban areas present the greater risk.[10] For example, the cities of the Vietnam, Laos and Cambodia are essentially malaria-free, but the disease is present in many rural regions.[11] By contrast, in Africa malaria is present in both rural and urban areas, though the risk is lower in the larger cities.[12] The global endemic levels of malaria have not been mapped since the 1960s, however, the Wellcome Trust, UK, has funded the Malaria Atlas Project[13] to rectify this, providing a more contemporary and robust means with which to assess current and future malaria disease burden.
Socio-economic effects
Malaria is not just a disease commonly associated with poverty, but is also a cause of poverty and a major hindrance to economic development. The disease has been associated with major negative economic effects on regions where it is widespread. A comparison of average per capita GDP in 1995, adjusted to give parity of purchasing power, between malarious and non-malarious countries demonstrates a fivefold difference (US$1,526 versus US$8,268). Moreover, in countries where malaria is common, average per capita GDP has risen (between 1965 and 1990) only 0.4% per year, compared to 2.4% per year in other countries.[14] However, correlation does not imply causation, and the prevalence is at least partly because these regions do not have the financial capacities to prevent malaria. In its entirety, the economic impact of malaria has been estimated to cost Africa US$12 billion every year. The economic impact includes costs of health care, working days lost due to sickness, days lost in education, decreased productivity due to brain damage from cerebral malaria, and loss of investment and tourism.[3] In some countries with a heavy malaria burden, the disease may account for as much as 40% of public health expenditure, 30-50% of inpatient admissions, and up to 50% of outpatient visits.[15]
References
- ↑ "Malaria: Geographic Distribution". CDC Malaria website. Retrieved 2007-06-15.
- ↑ 2.0 2.1 2.2 Breman J (2001). "The ears of the hippopotamus: manifestations, determinants, and estimates of the malaria burden". Am J Trop Med Hyg. 64 (1-2 Suppl): 1–11. PMID 11425172.
- ↑ 3.0 3.1 Greenwood BM, Bojang K, Whitty CJ, Targett GA (2005). "Malaria". Lancet. 365: 1487–1498. PMID 15850634.
- ↑ Hay S, Guerra C, Tatem A, Noor A, Snow R (2004). "The global distribution and population at risk of malaria: past, present, and future". Lancet Infect Dis. 4 (6): 327–36. PMID 15172341.
- ↑ Korenromp E, Williams B, de Vlas S, Gouws E, Gilks C, Ghys P, Nahlen B (2005). "Malaria attributable to the HIV-1 epidemic, sub-Saharan Africa". Emerg Infect Dis. 11 (9): 1410–9. PMID 16229771.
- ↑ Abu-Raddad L, Patnaik P, Kublin J (2006). "Dual infection with HIV and malaria fuels the spread of both diseases in sub-Saharan Africa". Science. 314 (5805): 1603–6. PMID 17158329.
- ↑ Layne SP. "Principles of Infectious Disease Epidemiology /" (PDF). EPI 220. UCLA Department of Epidemiology. Retrieved 2007-06-15.
- ↑ Greenwood B, Mutabingwa T (2002). "Malaria in 2002". Nature. 415: 670–2. PMID 11832954.
- ↑ Grover-Kopec E, Kawano M, Klaver R, Blumenthal B, Ceccato P, Connor S (2005). "An online operational rainfall-monitoring resource for epidemic malaria early warning systems in Africa". Malar J. 4: 6. PMID 15663795.
- ↑ Van Benthem B, Vanwambeke S, Khantikul N, Burghoorn-Maas C, Panart K, Oskam L, Lambin E, Somboon P (2005). "Spatial patterns of and risk factors for seropositivity for dengue infection". Am J Trop Med Hyg. 72 (2): 201–8. PMID 15741558.
- ↑ Trung H, Van Bortel W, Sochantha T, Keokenchanh K, Quang N, Cong L, Coosemans M (2004). "Malaria transmission and major malaria vectors in different geographical areas of Southeast Asia". Trop Med Int Health. 9 (2): 230–7. PMID 15040560.
- ↑ Keiser J, Utzinger J, Caldas de Castro M, Smith T, Tanner M, Singer B (2004). "Urbanization in sub-saharan Africa and implication for malaria control". Am J Trop Med Hyg. 71 (2 Suppl): 118–27. PMID 15331827.
- ↑ Hay SI, Snow RW (2006). "The Malaria Atlas Project: Developing Global Maps of Malaria Risk". PLoS Medicine. 3 (12): e473.
- ↑ Sachs J, Malaney P (2002). "The economic and social burden of malaria". Nature. 415: 680–5. PMID 11832956.
- ↑ Roll Back Malaria. "Economic costs of malaria". WHO. Retrieved 2006-09-21.