It is estimated that around 70 million non-immune adults travel each year to areas where they are at risk of contracting malaria. The Plasmodium protozoa (Malaria) is divided into different families ie. Plasmodium Falciparum, Vivax, Ovale and Malariae. Falciparum is the most lethal and kills more people every year from 1-2 million a year (WHO 1990) to 2-3 million a year (WHO 1995 ; PRISM 1996). The protozoa is carried by the anopheline mosquito that breeds in stagnant non-running fresh water.
Often advice regarding malaria may differ from country to country as local malarial strains differ and also change or mutate with time, thus you may find that advice you get from your own doctor at home differ when you actually arrive at your destination. If in doubt, heed the local medical recommendations. Since the antigenic structure of Plasmodium changes and differ from place to place and also from time to time, scientists have long been trying to get a malaria vaccine with limited success. It is rather like trying to hit a moving target all the time. To date, the malaria vaccine SPf66 is still in its very early stages of evaluation and not available for general use.
Apart from antimalarials, one cannot overemphasise the importance of applying insect repellants and adopting general clothing sensibilities where situation permits like wearing long trousers and sleeves to avoid bites. Especially so at dawn and dusk when the anopheline mosquito is most active.
Diving while on any sort of medication is always advised with caution since research into these interactions are scanty. It would also be rather difficult to get past an ethics committee to set up any meaningful double blind prospective study of significance.
Chloroquine was one of the first few effective treatments and prophylaxis that man had against malaria for the past 40 years but unfortunately it is not uncommon anymore to find chloroquine resistant strains esp. P. Falciparum in many parts of SE Asia, East Africa and the northerly countries of S.America.
Lariam or Mefloquine first emerged from the US Army malaria research programme at the time of the Vietnam war (1963-1976) and became available to the European traveller in 1985. It is still one of the more effective antimalarial agents generally available to the public, though it may not be the most tolerable of all medications. Its use has certainly been increasing recently. This also means more adverse reactions are being reported too. But the more ominous reality is that with more use, resistant strains are going to appear before long if not already.
They have been a few other new agents but are still in its early stages of research or been withdrawn because of toxic reactions to individuals. Amodiaquine is one example. This is no easy task as the antimalarial has to be both effective and also well tolerated with minimal side effects.
There is always a risk of side-effects with any medication. Neuropsychological and Gastrointestinal ones are well recognised in Lariam / Mefloquine.
Recent media publicity in the West has intensified worries concerning the safety profile of Lariam / Mefloquine after a few individuals suffered permanent psychological seqealae from taking it. Parliamentary and scientific debates has been at it for years but only come up with promises of more stringent guidelines when what we really need is a safer and effective alternative. This has been particularly acute in the UK, Canada and The Netherlands.
There is to date no other safer and more effective prophylactic alternative other than Lariam / Mefloquine in heavily endemic areas unless you want to go on vacation in a full sized spacesuit with its own life support systems! Well, I guess then you can leave your scuba-gear at home.
Protection comes at a price and often it is the more common side effects like dizziness, gastric upsets and vomiting that stops the traveller from taking it. Thus it is advisable to take it at least 2 weeks before travel and if a problem does arise, you still have time to see your doctor to discuss an alternative. It is imperative that an antimalarial be taken for 4 weeks after leaving the area as some protozoa go into a dormant stage (hypnozoites) in the liver for up to 10 years or more and flare up later.
At time of print the Department of Health in HK and UK has not issued any memos regarding Lariam / Mefloquine and I believe it is still widely available and has not been withdrawn despite some bad reports.
Until such a time the Department of Health in HK, UK or the US FDA decides to withdraw its use or when pharmaceutical firms are able to come up with a safer and more effective agent or regimen, Lariam / Mefloquine will continue to be my choice of an effective convenient prophylactic antimalarial in heavily endemic areas if tolerated.
There are other drug combinations of Chloroquine, Maloprim, Doxycycline and Proguanil for different geographical areas and one needs to make an informed decision rather than follow the herd instinct as to the flavour of the week in the local media.
If in doubt discuss your travel plans with your doctor and weigh up the risks of contracting malaria against the potential side effects of any medication.
Dr. Kim Chen
MB BCh BAO ( Belf )
MRCGP ( Lond )
DRCOG ( Lond )