Protecting travelers against malaria has becomeever more important as the number travelling overseas is constantly rising, with a disproportionate surge in visits to tropical areas where probability of malaria transmission is much higher compared to elsewhere. Each year around 1700 cases of malaria are reported in the UK, 1300 in the US, and 3000 in France.In the United Kingdom, about 3/4thof these cases are caused by Plasmodium falciparum, which causes the most severe form of malaria; five to 16 deaths happen annually and are almost always in cases of falciparum malaria.

If you think that among the infected most would be those visiting UK from abroad then you are absolutely wrong, in fact most infections are reported in travelerswho are residents of the UK. This reality makes antimalarials (chemoprophylaxis) a necessity for UK residents going abroad. Chemoprophylaxis is most important element of “ABCD” approach of malaria prevention, other elements are awareness of risk, bite avoidance and prompt diagnosis of malaria. Malaria becomes a major risk for travelers if they avoid chemoprophylaxis or if they take incorrect chemoprophylaxis. He a traveler needs help from a good travel clinic prior to embarking on a foreign tour.

“ABCD” approach to preventing malaria

Factors determining individual risk

A detailed itinerary needs to be presented to the travel clinic for assessing risk. The degree of transmission fluctuates markedly between different regions, even within a nation, and at different times of the year. For instance, the risk of contracting malaria in West Africa may reach as high as 6% per month of travel but on the Kenyan coast is considerably low at 1% per month; in Nairobi (the Kenyan capital), transmission is very low.

Apart from geographical factors, an individual’s risk depends on the length of stay in the endemic area and also activities undertaken: camping in a jungle for three weeks and three day stopoverin an urban area can’t be expected to pose same level of risk. Camping activity will pose much higher risk understandably.

P falciparum, P vivax, P ovale and P malariae are the fourspecies of malaria parasites that usually infect humans after the bite of an infected Anopheles spp mosquito, most common being P falciparum and P vivax. Falciparum malaria prevails in sub-Saharan Africa, and on the other hand vivax malaria prevails in the Indian subcontinent, China,Mexico, and Central America; both species are present in South America and South East Asia and.

Groups at particular risk

More than half of travellers who acquire malaria are found to have not taken advice before travelling. Scrutiny of imported malaria indicates that certain groups are at risk more than others. For instance, those taking rushed holidays and VFR travellers(those visiting friends and relatives abroad). VFR travellersaccount for 70% of malaria imported into the UK. Such groups need antimalarials badly.

How can bites be prevented?

Evading mosquito bites is critical and doubly beneficial as it helps to prevent other vector borne diseases like yellow fever or dengue as well. Dusk to dawn period is peak time for malaria mosquitoes to bite.

How do antimalarials work?

All malarial parasites advance in the liver after mosquitoinjects sporozoites. After at least seven days, merozoites emerge from the liver and infect RBCs (red blood cells), causing clinical symptoms of malaria to show up. Most antimalarial drugs eliminate parasites when they are present in the RBCs rather than in the liver.

How a drug regimen is chosen?

The choice of a particular drug for prophylaxis depends on (a) individual factors (health problems or medications, previous experience with antimalarials, and length of stay); and (b) the region visited (which gives information about the predominant malaria species and drug sensitivity).

Conclusion

Adherence to chemoprophylaxis (antimalarial regimen) is a vital component of success in preventing malaria. Malaria in travelers who have returned home is almost always linked with the failure to take any chemoprophylaxis, taking wrong chemoprophylaxis, or not honoring the drug regimen. Travelersneed to be counseled by pharmacist about the importance of completing the course of antimalarials.

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