Getting Ready: Malaria
|Malaria is a serious parasitic infection of the bloodstream. It is the most important infectious threat to travellers to the tropics. Nearly two million people die each year of malaria, most of whom are children in Africa. Several hundred cases occur in Canadian travellers each year. For some reason, we tend to get more cases per capita than in the U.S. A few Canadians die each year.|
The factors which will affect your risk of acquiring malaria include:
- Your destination
- The duration of your stay
- The time of year
- The precautions you take
- ...and once again... luck!
It is transmitted through the bite of the female anopheles mosquito. The symptoms of malaria may occur in as little as 10 days after infection, but sometimes may not occur for several weeks or months after exposure.
|Malaria resembles the flu, and may in fact mimic many illnesses. The classical symptoms include headache, chills, feeling hot and cold and muscle aches and pains. The most important sign of malaria is FEVER. Classically the fever recurs every 48 hours, but this is not always the case.|
There is a fair bit of controversy and misinformation regarding both malaria and its prevention. Here are the facts!
- There are four strains, and only four strains, of human malaria
- Plasmodium falciparum is the most serious strain, and the only one that may be fatal. This same strain is the one responsible for most of the drug resistance around the world. Drug-resistant malaria is not a new thing. It has been around since the 60's, but its distribution has been expanding. Chloroquine-resistant malaria is now found in all malarious areas of the world with the exception of The Middle East, Haiti / Dominican Republic and Central America.
- Personal measures such as DEET- containing repellents and mosquito nets are extremely important in preventing malaria
- Malaria is often misdiagosed and mistreated in travellers who return home
- Malaria is probably overdiagnosed, though hopefully properly treated in the tropics
- Malaria is a treatable infection, as long as it is treated promptly and properly (sort of like a heart attack)
- It is a myth that once you have malaria, you have it for life. There are two strains of malaria which may persist in the liver and recur, Plasmodium vivax and Plasmodium ovale. However, this "dormant" stage can be eradicated with the drug primaquine.
- Malaria is usually a preventable infection. There are good drugs to prevent malaria. Unfortunately, there are no perfect ones.
- Many people say that antimalarials are worse than the disease. Ask someone who has had cerebral malaria!
Personal Preventive Measures
These precautions will greatly reduce your risk of developing malaria, as well as other insect-borne infections. Consider the following:
DEET-containing repellents are available in different concentrations, ranging from about 6% to 95%. The higher the concentration, the longer its protection. 95% DEET will give about 95% protection for up to 10 hours. 30% provides protection for up to 7 hours, and 10% - for 3 to 4 hours. Use no more than 30% DEET under the age of 12
- Use up to 10% DEET three times daily under the age of 12
- Use up to 10%DEET once daily only in kids 6 months to 2 years of age
- No DEET under 6 months of age
- DEET should be used cautiously in small children, as it may be absorbed through the skin. Keep it away from the child’s eyes, hands and mouth. Wash it off after going back indoors.
- Microencapsulated products (e.g. Ultrathon) are slow-release and result in less absorption at lower concentrations
- Others useful and perhaps more natural preparations include citronella, soybean oil (Blocker Liquid Lotion) , Autan (Bayrepel) , and Picardin (not available in Canada)
- Buzzers, garlic, vitamin B1 and reruns of I Love Lucy are likely less effective!
- If you are in an area where there is also dengue fever, take precautions during the day as well.
Many people tell me that they are concerned because their DEET ate away at their shoes/ watch band/ car upholstery, etc. This is unfortunate, BUT IT WILL NOT DO THAT TO YOUR SKIN! As I tell my patients, don’t put it in your eyes, don’t drink it, don’t bathe your kids in it, keep it off your iPod, and apply it where it is supposed to go!
Distribution of malaria
Malaria occurs in many, but not all countries in the tropics. Sometimes it is only a rural problem, but in most of Africa and Asia, it occurs in both urban and rural areas. It may be seasonal as well. For example, if you visit New Delhi in January you’ll probably need a scarf at night, so there is little or no risk of malaria. Later in the year, when it is warm and wet, the risk is significant. For a great resource to find about the malaria risk at your destination, go to CDC’s Malaria Risk Map Application.
Antimalarial medications do not prevent infection with the malaria parasite, rather, they suppress the symptoms of the infection by killing the parasites either in the liver or as they leave the liver and enter the bloodstream. This should be considered a good thing when one realizes that headache, coma and death are three of the symptoms. There is no perfect antimalarial - i.e. one that is 100% effective, and always without side effects. The choice of antimalarial depends upon the destination and the patient, i.e. medical problems, medications and past experience with antimalarials.
For parts of the world where the strains of malaria are sensitive to chloroquine, then chloroquine is the drug of choice. Unfortunately, these areas have shrunk over the past few decades. The only areas where chloroquine-sensitive falciparum malaria still occurs include Haiti, some rural parts of Mexico and Central America, and some rural part of the Middle East. Most travellers do not visit these areas. Dominican Republic is the main chloroquine-sensitive destination for most North Americans.
Chloroquine has been used for many years to prevent malaria. Like some other antimalarials, it is started the week before entering the malarious area, taken weekly while away, and continued for four weeks after leaving the malarious area. It tastes quite bitter and so should be taken quickly with food and lots of water. In tropical countries, but not here, it is available as a liquid that might be easier to take for children. It must be kept out of the reach of these same children as accidental ingestion can prove fatal. Other antimalarials such as Malarone are also effective in chloroquine-sensitive areas.
There are now three good drugs that can be used to prevent chloroquine-resistant falciparum malaria. Your choice might depend upon your age, medical history, the duration of your trip, the possibility of pregnancy, your past history with antimalarials, and last but not least … your budget!
We could write volumes on this drug! To say that it has been the subject of some controversy would be an understatement. It was first developed in the 60s during the Vietnam War because of the emergence of chloroquine-resistant falciparum malaria.
Mefloquine is taken weekly, also beginning the week before travel, weekly while away, and for four weeks after travel. It must be taken with food, preferably in the evening, and preferably not with a bucket of alcohol.
Minor side effects occur in up to 15% of people. These include stomach upset, dizziness, vivid (good, bad, erotic and otherwise) dreams, insomnia and anxiety. More serious side effects, such as seizures and psychosis, are relatively rare. These side effects are usually transient, and may dissipate with time. Remember, most side effects do not occur in most people most of the time. Many of the same adverse effects are reported with chloroquine.
I have heard just about everything there is to hear about mefloquine. I have also had a few disastrous experiences in overseas volunteers. All of these, however, have occurred when the drug was taken with alcohol and other drugs.
Mefloquine should not be used in those with a history of epilepsy, depression, anxiety, panic disorder, cardiac rhythm abnormalities, and perhaps those who have had a problem on it in the past. It is safe in children, and may also be used in pregnant women who have no choice but to travel to malarious areas. Mefloquine is a touch expensive ($5.30 in Canada, up to $10.00 in the USA), so some people may chose a cheaper alternative. It may often be purchased for less in some tropical countries. A less expensive generic brand is available in many countries.
The dosage varies with body weight. The pill is scored, so it can usually be easily broken into quarters, and even less. For children, it can then be crushed up and taken with something tasty and hopefully non-infectious.
Doxycycline is an antibiotic, which is quite effective in preventing chloroquine-resistant falciparum malaria. It can be used in those who can not take mefloquine, and those who do not want to take mefloquine. It must be taken on a daily basis, starting the day before entering the malarious area, daily while away, and for four weeks after departure.
It must be taken with lots of water, or it may irritate the esophagus. You’ll get heartburn from hell! As it can cause photosensitivity, sun precautions must be used. It will also predispose women to yeast infections. It is contraindicated in pregnancy and children under the age of 8, as it can cause staining of the teeth. The commonest complaint I hear about this drug is “stomach ache” and diarrhea. It is effective along the borders of Thailand and Cambodia / Burma, where mefloquine isn’t.
Malarone, the newest antimalarial, is a combination of proguanil and atovoquone. Proguanil has been around for years, and is an alternative to chloroquine for malaria prophylaxis. Atovoquone has been in use for the treatment of Pneumocystis carinii and Toxoplasma gondii in patients infected with HIV. This drug is started the day prior to arrival in the malarious area, taken on a daily basis while there, and continued for only 7 days after leaving the malarious area. It is known as a “causal” prophylactic, that is, it actually kills the malaria parasites while they are still in the liver, before they get into the bloodstream.
Thankfully, this antimalarial is almost free of side effects. It may cause an upset stomach, and mouth ulcers can occur secondary to the proguanil component. I have only seen this happen in kids with braces on their teeth. It should not be used in pregnant women. Its main drawback is its price – almost 5 dollars a pill in Canada, and much more in the U.S. Therefore, it is an extremely useful pill for those taking short trips, those with good private medical plans, those with lots of money, and those who cannot take mefloquine or doxycycline.
This is perhaps an underused antimalarial option. It has been used for decades to eliminate the liver stage of the parasite. Taken prophylactically in a dose of 30 mg/day, and for 7 days after leaving the malarious area, it is very effective. One catch – you need to do a blood test – a G6PD level, to make sure it is safe for you to take primaquine.
This may be appropriate for someone who thinks that they might have malaria, but cannot receive prompt, good medical attention. A variation of that is that even if you can find reasonable medical care, it behooves you to be acquainted with the proper choices for the treatment of malaria. In many cases in the tropics, malaria is diagnosed clinically, and not with bloods smears. Also remember, that "local" people might have some immunity to malaria. You do not. The treatment that might suffice for them will not be adequate for you.
There are a few medications that would be appropriate for the treatment of malaria. In most cases, one should assume that he or she has chloroquine-resistant falciparum malaria …. remember, that potentially deadly strain! They include:
- quinine sulfate taken 3 times daily for 5 to 7 days
- Malarone - 4 tablets daily for 3 days
- Artemesinin derivatives – these medications are available throughout most of the malarious world
ACT refers to artemesinin-combined therapy,that is, a form of artemesinin in combination with a second drug, such as amodiaquine or lumefantrine. By using combination drugs, it is hoped that the inevitable drug resistance can be delayed.
There are several different preparations of artemesinin that are available under various names, including Riamet, Cotexcin, Artenam, Alaxin, Arsumax and Coartem. These drugs are widely available over there. There is some concern about counterfeit malaria drugs in Africa. Shop carefully! Artenam has recently become available in the USA.
Travellers occasionally die from malaria, both while away and in "civilized" places like Canada! This happens because of delayed or incorrect diagnosis (the fault of the patient or the doctor), or inadequate or incorrect treatment (usually the fault of the doctor). As I mentioned, you will hear lots about malaria and antimalarials. Much of it will be untrue, and some of it, downright dangerous. It is up to you to be well-informed before you leave. Trying to search the internet for information in rural Ghana with a temperature of 40 degrees Celsius and a slow-speed connection can be difficult to say the least!
Should you visit the local doctor because of your fever, in Africa, Asia or other parts of the tropics, you will likely be diagnosed with malaria. This may be because of positive test, or just because malaria is common, so they will treat you for it. If you don’t get better, you may then be diagnosed with and treated for typhoid fever. Sometimes you will get treated for both infections at the same time. That approach is not ideal, but again, as I tell my volunteers, I don’t think the doctor will kill you with his 7 different pills. But it is up to you to know which ones are worthwhile.
There are some real concerns about the overdiagnosis of malaria in the tropics, such as:
- It gives many who allegedly suffered with malaria the impression that it is only a mild illness.
- It perpetuates the impression that antimalarials do not work.
- Other important diagnoses may be missed.
- Travellers are exposed to unnecessary and potentially dangerous medications.
- The overuse of drugs for the treatment of malaria may speed up the development of drug resistance.
Malaria is now a greater threat to travellers than ever before. Drug resistant falciparum malaria is spreading, and unfortunately, there is no effective vaccine on the horizon. Several myths regarding this infection seem to persist amongst both medical and non-medical personnel alike. Let's try to dispel the most popular ones.
Once you have malaria... you have it for life
Not true. While I have seen numerous patients who are convinced that they have suffered relapses on a yearly basis since World War II, this is rarely the case. There are two strains of malaria, P. vivax and P. ovale, which may persist in the liver as hypnozoites for months and even years and cause such recurrences, but they can easily be eradicated by the use of the drug primaquine. This is usually administered following a course of chloroquine. Having said that, there are now some interesting strains of P. vivax in Irian Jaya and Papua New Guinea which are displaying varying degrees of resistance in both chloroquine and primaquine.
There is no longer an effective antimalarial.
Not true. While there is no perfect antimalarial, drugs such as mefloquine, doxycycline and Malarone offer excellent protection if used properly. When combined with personal measures such as insect repellents and mosquito netting, the risk of malaria to most travellers is very small. While we do see cases of malaria due to drug failure, the great majority of patients who develop malaria do so because they have either stopped their antimalarial, or are on the wrong one.
Taking antimalarials only masks the disease.
Not exactly a myth, but a misunderstanding. In fact, it is true. Most antimalarials do not prevent infection following a mosquito bite. Rather, they kill the parasites as they enter our red blood cells. This prevents them from multiplying, invading other red blood cells, and clogging arteries to our brain and other vital organs. As a result we don't suffer the fevers, chills, headaches and other joys of malaria. We continue our antimalarials for four weeks after leaving a malarious area in the hope that they will continue to mask, or suppress any symptoms until the risk of disease has likely passed. Malarone, as I mentioned, kills the parasites while they are still in the liver, so only needs to be taken for seven days after leaving the malarious area.
The drugs are worse than the disease.
Tell that to someone who has almost died of malaria. Antimalarials do have side effects…in some people, some of the lime. All drugs may. Between 15-20% of travellers will experience stomach upset, dizziness, vivid dreams or emotional symptoms such as anxiety while taking mefloquine, the most commonly prescribed antimalarial. That means that 80-85% of people will be fine. The side effects are usually transient and tolerable. Serious adverse reactions such as psychosis or seizures are rare. Don’t mix mefloquine with alcohol or other drugs, and take doxycycline with lots of water during the day. Compare that to the real thing, which may be fatal. No contest!
I am immune to malaria.
Usually not true. People who grew up in malarious areas such as in tropical Africa do develop a relative immunity to the parasite. This does not mean that they don't get infected. Rather, their symptoms of malaria maybe milder than a non-immune person or they may even have circulating parasites in the absence of any symptoms. However this immunity is mostly lost after living through several Stanley Cup playoffs in Canada due to the lack of constant exposure to the parasite. Therefore, most Canadians and Americans returning to their native countries are quite susceptible to malaria, and in fact account for the majority of our imported cases.
If I take antimalarials, there will be nothing left to treat me if I do get malaria.
Wrong again. There are several drugs used to treat malaria, including quinine, Malarone and derivatives of artemesinin. The drug of choice may depend upon where you are, i.e. downtown Toronto versus Timbuktu, and how sick you are. Sometimes a drug such as quinine will have to be used with extra caution if the patient has recently been on mefloquine, as all can have cardiac side effects. But having been on an antimalarial certainly doesn't leave a malaria sufferer without additional treatment options. Malaria is a treatable disease when treated quickly and correctly. When travellers die of malaria, it is usually because of delayed or inadequate treatment.
FEVER IN A RETURNING TRAVELLER IS MALARIA UNTIL PROVEN OTHERWISE. YOU SHOULD SEEK IMMEDIATE MEDICAL ATTENTION.
Do not count on the doctor to ask if you have recently been to Nigeria. Most people haven’t! Tell him or her. Demand a malaria smear and proper treatment and followup.