Protection against malariaBMJ 1998; 317 doi: http://dx.doi.org/10.1136/bmj.317.7171.1508 (Published 28 November 1998) Cite this as: BMJ 1998;317:1508
Malaria can be prevented. Unfortunately, travellers to areas where malaria is common often put themselves at risk of contracting the disease by ignoring the key steps in malaria prevention. The steps are simple but if ignored can result in unnecessary morbidity and, in some cases, death. The key steps to protect against malaria are:
A—Awareness: know about the risk of malaria
B—Bites by mosquitoes: prevent or avoid
C—Compliance: with appropriate drug regimen
D—Diagnosis: diagnose malaria swiftly and obtain treatment promptly.
Incidence of side effects from prophylactic drugs
The number of cases of malaria imported into the United Kingdom is rising (figure), and over half of them are potentially fatal (falciparum malaria). The risks from the disease must be compared sensibly with the risks associated with the drugs recommended for prophylaxis. Obtaining true figures for the incidence of side effects is difficult and in some cases controversial. This is partly because as doctors become more aware of potential side effects, more side effects are looked for and then reported. Also, it is virtually impossible to perform anything other than observational studies on side effects because sending people to malarious areas with placebo drugs only would be unethical.
Two other factors make it difficult to determine the incidence of side effects. Firstly, of the huge number of people taking antimalaria drugs some will get concurrent symptoms and diseases while abroad, and deciding whether to attribute these to the antimalaria drugs is difficult. Secondly, attributing subjective side effects to drugs is a common phenomenon, even for placebo drugs.
With short acting drugs (for example, proguanil, which is taken daily) side effects usually occur after just one dose. With longer acting drugs (for example, mefloquine, which is taken weekly), side effects may not become apparent until after the third dose.
Two large studies have reported the incidence of side effects of mefloquine compared with chloroquine and proguanil. Barrett et al found that both regimens had similar rates of any side effect occurring (40%), although most side effects were trivial.1 About 0.7% of travellers taking mefloquine reported severe, disabling neuropsychiatric symptoms compared with 0.09% of people taking chloroquine and proguanil. Also a significantly higher number of moderate neuropsychiatric symptoms occurred in mefloquine users compared with travellers who took chloroquine and proguanil. Steffen et al found that 18.8% of travellers taking mefloquine had experienced side effects while 30.1% of the chloroquine and proguanil group reported problems.