Malaria prophylaxis
From Wikipedia, the free encyclopedia
Malaria prophylaxis is the prevention of malaria.
Contents |
[edit] Rationale
In the UK, there are between 1500 and 2000 cases of malaria reported every year; with 5 to 15 deaths from malaria every year.
[edit] Basic advice
The ABCD of malaria prevention are:
- Awareness of risk;
- Bite prevention;
- Chemoprophylaxis; and
- rapid Diagnosis and treatment.
A lot of emphasis is placed on chemoprophylaxis, but it must be remembered that the other basics of malaria prevention are just as important.
[edit] Bite prevention
Travellers to malarious areas are advised to wear long clothes that cover as much of the skin as possible. Exposed parts of the body should be treated with insect repellant. When sleeping, insecticide-impregnated bed nets should be used.
[edit] Chemoprophylaxis
Chemoprophylaxis is the practise of taking regular anti-malarial medication in order to stop a traveller from becoming unwell with malaria.
Travellers should always seek advice from a specialist. It should be remembered that all national and international guidelines are just that: guidelines. The circumstances for each visit are different and therefore varying advice will be given for each traveller. Sometimes, the advice given is that no chemoprophylaxis is given.
Prior to the emergence of widespread chloroquine resistance, malaria prophylaxis was very simple: one chloroquine tablet a week was sufficient cover.
[edit] Drug regimens
The following regimens are recommended by the WHO, UK HPA and CDC:
- chloroquine 300 to 310 mg once weekly, and proguanil 200 mg once daily(started one week before travel, and continued for four weeks after returning);
- doxycycline 100 mg once daily (started one day before travel, and continued for four weeks after returning);
- mefloquine 228 to 250 mg once weekly (started two-and-a-half weeks before travel, and continued for four weeks after returning);
- Malarone® 1 tablet daily (started one day before travel, and continued for 1 week after returning).
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:
- Dapsone 100 mg and pyrimethamine 12.5 mg once weekly (available as a combination tablet called Maloprim® or Deltaprim®): this combination is not routinely recommended because of the risk of agranulocytosis;
- Primaquine 30 mg once daily (started the day before travel, and continuing for seven days after returning): this regimen is not routinely recommended because of the need for G-6-PD testing prior to starting primaquine (see the article on primaquine for more information).
- Quinine sulphate 300 to 325 mg once daily: this regimen is effective but not routinely used because of the unpleasant side effects of quinine.
[edit] Suppressive prophylaxis
Chloroquine, 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.
[edit] Causal prophylaxis
Causal 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.
[edit] References
- 2007 guidelines are available from the UK Health Protection Agency website as a PDF file and includes detailed country-specific information for UK travellers.
- The World Health Organisation provides country-specific advice on malaria prevention.
- The Centers for Disease Control and Prevention website hosts constantly updated country-specific information on malaria. The advice on this website is less detailed, is very cautious and may not be appropriate for all areas within a given country. This is the preferred site for travellers from the US.
HPA and WHO advice are broadly in line with each other (although there are some differences). CDC guidance frequently contradicts HPA and WHO guidance.
