Microsoft word - malaria.doc

Malaria is an infectious disease that is widespread in tropical and subtropical regions. It infects between 300 and 500 million people every year and causes between one and three million deaths annually, mostly among young children in Sub-Saharan Africa. Malaria is not just a disease commonly associated with poverty, but is also a cause of poverty and a major hindrance to economic development. Malaria is one of the most common infectious diseases and an enormous public-health problem. The disease is caused by protozoan parasites of the genus Plasmodium. The most serious forms of the disease are caused by Plasmodium falciparum and Plasmodium vivax, but other related species (Plasmodium ovale and Plasmodium malariae) can also infect humans. This group of human-pathogenic Plasmodium species are usually referred to as malaria parasites. Malaria parasites are transmitted by female Anopheles mosquitoes. The parasites multiply within red blood cells, causing symptoms that include symptoms of anemia (light headedness, shortness of breath, tachycardia etc.), as well as other general symptoms such as fever, chills, flu-like illness, and in severe cases, coma and death. Malaria transmission can be reduced by preventing mosquito bites with mosquito nets and insect repellents, or by mosquito control by spraying insecticides inside houses and draining standing water where mosquitoes lay their eggs. Unfortunately, no vaccine is currently available for malaria. Instead preventative drugs must be taken continuously to reduce the risk of infection. These prophylactic drug treatments are simply too expensive for most people living in endemic areas. Malaria infections are treated through the use of antimalarial drugs, such as chloroquine or pyrimethamine, although drug resistance is increasingly common. Malaria has probably infected humans for over 50,000 years, and may have been a human pathogen for the entire history of our species. Indeed, close relatives of the human malaria parasites remain common in chimpanzees, our closest relatives. References to the unique periodic fevers of malaria are found throughout recorded history, beginning in 2700 BC in China during the Xia Dynasty.The term malaria originates from Medieval Italian: mala aria — "bad air"; and the disease was formerly called ague or marsh fever due to its association with swamps. Scientific studies on malaria made their first significant advance in 1880, when a French army doctor working in Algeria named Charles Louis Alphonse Laveran observed parasites inside the red blood cells of people suffering from malaria. He therefore proposed that malaria was caused by this protozoan, the first time protozoa were identified as causing disease For this and later discoveries, he was awarded the 1907 Nobel Prize for Physiology or Medicine. The protozoan was called Plasmodium by the Italian scientists Ettore Marchiafava and Angelo Celli.A year later, Carlos Finlay, a Cuban doctor treating patients with yellow fever in Havana, first suggested that mosquitoes were transmitting disease to humans. However, it was Britain's Sir Ronald Ross working in India who finally proved in 1898 that malaria is transmitted by mosquitoes. He did this by showing that certain mosquito species transmit malaria to birds and isolating malaria parasites from the salivary glands of mosquitoes that had fed on infected birds. For this work Ross received the 1902 Nobel Prize in Medicine. After resigning from the Indian Medical Service, Ross worked at the newly-established Liverpool School of Tropical Medicine and directed malaria-control efforts in Egypt, Panama, Greece and Mauritius. The findings of Finlay and Ross were later confirmed by a medical board headed by Walter Reed in 1900, and its recommendations implemented by William C. Gorgas in the health measures undertaken during construction of the Panama Canal. This public-health work saved the lives of thousands of workers and helped develop the methods used in future public-health campaigns against this disease. The first effective treatment for malaria was the bark of cinchona tree, which contains quinine. This tree grows on the slopes of the Andes, mainly in Peru. This natural product was used by the inhabitants of Peru to control malaria, and the Jesuits introduced this practice to Europe during the 1640s where it was rapidly accepted. However, it was not until 1820 that the active ingredient quinine was extracted from the bark, isolated and named by the French chemists Pierre Joseph Pelletier and Joseph Caventou. In the early twentieth century, before antibiotics, patients with syphilis were intentionally infected with malaria to create a fever. By accurately controlling the fever with quinine, the effects of both syphilis and malaria could be minimised. Although some patients died from malaria, this was preferable than the almost-certain death from syphilis. Although the blood stage and mosquito stages of the malaria life cycle were established in the 19th and early 20th centuries, it was not until the 1980s that the latent liver form of the parasite was observed. The discovery of this latent form of the parasite finally explained why people could appear to be cured of malaria but still relapse years after the parasite had disappeared from their bloodstreams. Distribution and impact Further information: Diseases of poverty, Tropical disease Areas of the world where malaria is endemic (coloured blue). Malaria causes about 350–500 million infections in humans and approximately one to three million deaths annually — this represents at least one death every 30 seconds. The vast majority of cases occur in children under the age of 5 years; 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.Indeed, if the prevalence of malaria stays on its present upwards course, the death rate could double in the next twenty years. 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. 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 tuberculosis most common in the old.However, in areas of unstable malaria transmission, HIV does contribute to the incidence of severe malaria in adults during malaria outbreaks. There is also a high correlation between HIV and malaria. This correlation has lead to scientific research that suggests that malaria itself is a major contributor to the spread of HIV. This study shows that, "Higher viral load causes more HIV transmission, and malaria causes high HIV viral load." Malaria is presently endemic in a broad band around the equator, in areas of South America, South and Southeast Asia, parts of the Middle East and Oceania, and much of Africa; however, it is in sub-Saharan Africa where 85– 90% of malaria fatalities occur. The geographic distribution of malaria within large regions is complex, and malarial and malaria-free areas are often found close to each other. In drier areas, outbreaks of malaria can be predicted with reasonable accuracy by mapping rainfall. Malaria is more common in rural areas than in cities; this is in contrast to dengue fever where urban areas present the greater risk. For example, the cities of the Philippines, Thailand and Sri Lanka are essentially malaria-free, but the disease is present in many rural regions. By contrast, in West Africa, Ghana and Nigeria, malaria is present throughout the entire country, though the risk is lower in the larger cities. Social and 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 demonstrate 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. 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.[14] 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.

Source: http://www.globalefforts.org/downloads/malaria.pdf