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Malaria prophylaxisMalaria prophylaxis is the prevention of malaria. Malaria is thought to be one of the oldest infectious diseases, evolving around 10,000 years ago. The development of virulence in the parasite has been demonstrated using genomic mapping of samples from this period, confirming the emergence of genes conferring a reduced risk of developing the malaria infection. References to the disease can be found in manuscripts from ancient Egypt, India and China, illustrating its wide geographical distribution. The first treatment identified is thought to be Quinine, one of four alkaloids from the bark of the Cinchona tree. Originally it was used by the tribes of Ecuador and Peru for treating fevers. Its role in treating malaria was recognised and recorded first by an Augustine monk from Lima, Peru in 1633. Seven years later the drug had reached Europe and was being used widely with the name ‘the Jesuit's bark’. From this point onwards the use of Quinine and the public interest in malaria increased, although the compound was not isolated and identified as the active ingredient until 1820. By the mid-1880’s the Dutch had grown vast plantations of cinchona trees and monopolised the world market. Quinine remained to be the only available treatment for malaria until the early 1920’s. During the First World War German scientists developed the first synthetic antimalarial compound – Atabrin and this was followed by Resochin and Sontochin derived from 4-aminoquinoline compounds. American troops, on capturing Tunisia during the Second World War, acquired, then altered the drugs to produce Chloroquine. The development of new antimalarial drugs spurred the World Health Organization in 1955 to attempt a global malaria eradication program. This was successful in much of Brazil, the US and Egypt but ultimately failed elsewhere. Efforts to control malaria are still continuing, with the development of drug-resistant parasites presenting increasingly difficult problems. Additional recommended knowledge
Basic preventionThe ABCD of malaria prevention are:
Suppressive prophylaxisChloroquine, proguanil, mefloquine, and doxycycline are suppressive prophylactics. This means that they are only effective at killing the malaria parasite once it has entered the erythrocytic stage (blood stage) of its life cycle, and therefore have no effect until the liver stage is complete. That is why these prophylactics must continue to be taken for four weeks after leaving the area of risk. Causal prophylaxisCausal prophylactics target not only the blood stages of malaria, but the initial liver stage as well. This means that the user can stop taking the drug seven days after leaving the area of risk. Malarone® and primaquine are the only causal prophylactics in current use. ChemoprophylaxisPrior to the emergence of widespread chloroquine resistance, malaria prophylaxis was very simple: one chloroquine tablet a week was sufficient cover. The aims of malaria treatment, in broad terms are to alleviate symptoms (caused by the erythrocytic phase), to prevent relapses (caused by the hypnozoites of vivax and ovale) and to prevent further transmission of the parasite (occurs through gametocytes using the anopheles mosquito as a vector). The principals of treatment depend on four factors, these being: the type of infection, [i|140|the severity of infection], the status of the host and any associated conditions or diseases present in the host. There are approximately 14 antimalarials that are advised for use in the prevention and treatment of uncomplicated malaria. These will be discussed individually with particular attention to the specific recommended usage for each drug. Antimalarial drugsAntimalarial drugs are designed to prevent or cure malaria. Some antimalarial agents, particularly chloroquine and hydroxychloroquine, are also used in the treatment of rheumatoid arthritis and lupus associated arthritis. There are many of these drugs currently on the market. This is a partial list.
Drug regimensThe following regimens are recommended by the WHO, UK HPA and CDC:
What regimen is appropriate depends on the country or region travelled to. This information is available from the UK HPA, WHO or CDC (links are given below). Doses depend also on what is available (e.g., in the US, mefloquine tablets contain 228 mg base, but 250 mg base in the UK). The data is constantly changing and no general advice is possible. Doses given are appropriate for adults and children aged 12 and over. Other chemoprophylactic regimens that are available:
See alsoReferences
HPA and WHO advice are broadly in line with each other (although there are some differences). CDC guidance frequently contradicts HPA and WHO guidance. |
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Malaria_prophylaxis". A list of authors is available in Wikipedia. |