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Malaria is the bully of the world, causing suffering, misery and death since time immemorial. It can be considered among the most important of all infections on this planet. Malaria was once common in the US and other temperate areas--for example, it was in the Tennessee Valley until WWII; it was common in Boston at the turn of the century; it was even present in Northern Europe; and Rome used to be one of the most malarious areas in the world. In the past decades this disease has made a most unwelcome comeback. Malaria in fact comes from Italian, meaning bad air, which is what malaria was once attributed to.
Over 2.5 million people die from this disease each year and nearly one-quarter billion people are infected with malaria. Spread by the bite of the female anophelene mosquito, there are 4 species of this parasite that infect humans: Plasmodium vivax, P. ovale, P. malariae and P. falciparum. They have an extremely complicated life-cycle but we can simplify it somewhat: when an infective mosquito bites you and starts sucking blood, parasites gets into your system. Within 30 minutes they invade the liver and go through a maturation phase (in the cases of ovale and vivax, some hibernate only to awaken years to decades later). When the parasite is ready, it breaks out of the liver and reenters the blood. Then they invade your red blood cells. Then the parasites eat the contents of our red blood cells to make more of themselves. The red blood cell will burst when it is full of new parasites, and these will then invade other red blood cells. The timing of the invasion and replication is specific for each type of malaria and accounts for the cyclical patterns of symptoms. After several cycles of invasion and multiplication, some malaria organisms turn into sexual forms which, when taken up by the next mosquito fishing for its a blood meal, renews the cycle for the next person bitten.
The incubation time varies between species: between 12-30 days in general, but P. malariae & P.vivax can take months--even more than a year. Victims feel tired, weak, have muscle aches, and a mild headache which is followed in 1-2 days by a three-stage attack: shaking chills (cold stage); high fever (hot stage); marked diaphoresis (sweating stage). A full attack takes 4-8 hours, often occurring during mid-day. Other signs and symptoms include severe headache, fatigue, dizziness, fast pulse, loss of appetite, dry cough, crampy abdominal pain, even diarrhea, cold sores or sore throat in some cases (Sounds like the flu, doesn't it?). The spleen--an organ in our bellies which manages blood--enlarges, and you can turn jaundiced (a yellow or orange hue to the skin and eyeballs from the chemicals released by the ruptured red blood cells). Classically, there is a pattern to the fevers: every other day with P. vivax, ovale, falciparum and every third day pattern with P. malariae, but up to 1/3 patients have irregular patterns and this is notoriously so with the worst type of malaria, P. falciparum.
While all four species can make you very ill, Falciparum Malaria is the worst and is the most likely to kill. Complications include Cerebral Malaria (the deadliest type--malaria inside the blood vessels of the brain); hyperpyrexia (extremely high body temperature); Blackwater Fever (intravascular hemolysis--which means blood cells burst open in large numbers and can cause Kidney Failure); gastrointestinal disease (either a hepatitis-like syndrome but without liver failure, or a dysentery-like diarrhea syndrome); Algid Malaria (which is a superimposed septicemia--bacteria in the blood--with adrenal gland failure); pulmonary edema (fluid in the lungs); and hypoglycemia or low blood sugar. In addition, pregnancies often abort or mothers develop premature labor: there is also an increased risk of dying for mothers in their first pregnancy.
In regions where malaria is endemic (constantly present) children suffer the most, and if they survive through childhood they become semi-immune which gives a some protection against serious attacks as long as that person is repeatedly exposed to malaria; however, if a semi-immune person leaves a malarial area area for more than a couple of years, they lose all their immunity.
Diagnosis is made on clinical grounds--signs and symptoms--and by blood smears looking for the parasites in the red blood cells. Finding the parasite in the blood is the most important. A thick and thin blood smear are both necessary--the thick is used to see if any parasites are present and the thin is used to identify the species. This latter smear is very important as falciparum malaria needs to be ruled out. There is also a new blood test card that rapidly looks for malaria using antibodies and it looks like it will become very useful but is not yet approved for use in the United States.
There are different ways of treating malaria, and the medications used varies between countries, between the regions where the parasite was picked up, by the species of malaria, and by the resistance pattern to medications the malarial organism may have. Some of the available drugs include quinine (which may be why British expatriates seem to favor gin and tonic! Tonic water has quinine...), quinidine, mefloquine, chloroquine, atabrine, tetracycline, doxycycline, primaquine (to eradicate the hibernating forms of ovale and vivax), proguanil, malarone, and artemesenin compounds which Chinese physicians have been prescribing for millennia to treat fevers. The last one in this list is not yet available in the USA. Many of the medications used to treat malaria have potentially serious side effects. Medication is not the only tool needed to treat malaria--supportive care is essential (often inside an intensive care unit), and treating falciparum complications is critical.
There is good news: malaria is preventable! The formula to avoid malaria has two equally important parts: avoid mosquito bites and take malaria protective medications (AKA chemoprophylaxis). By avoiding mosquito bites (especially between dusk and dawn--this includes sleeping under a net or in a screened room, wearing insect repellents on clothing and exposed skin as well as wearing long sleeves/pants when outside). The medication you need depends on where you are going, but unfortunately this is complicated. The old standby, chloroquine, hardly works anymore. The main alternatives in the USA are malarone and mefloquine. Both offer excellent protection, but mefloquine has a reputation for causing sleep and emotional problems in a minority of users: in addition, it is absolutely forbidden for use by people who have seizures or psychiatric history. Doxycycline is another choice, but it is not as convenient, and it too has potential side-effects: yeast infections in women, gastric problems, cannot be given to children or taking during pregnancy and rarely sun reactions.
There is no vaccine, despite years of hard work by scientists to develop one.
Malaria is a serious disease. Like many others we once thought we had nearly conquered, it has come back to haunt us. In the 1960s when the war against malaria looked like a certain victory, research into vaccines and medications faltered because money was diverted elsewhere (the same sad story is true for TB). Today, most of the people suffering from malaria are poor and can barely afford treatment. Pharmaceutical companies are unlikely to invest much effort and money into such a non-profitable endeavor, but as malaria spreads again, and invades the once secure zones of the developed world things may change and funding may once again appear. Until then, for travelers, avoidance is of the essence--with personal protective measures and chemoprophylaxis. Before you travel to to a developing country, seek expert guidance from specialists in travel and tropical medicine--don't rely on regular doctors, because when it comes to travel, you want someone who spends time and energy keeping up to date in the field. A list of such specialists can be had from the American Society of Tropical Medicine and Hygiene (astmh.org) as well as the International Society of Travel Medicine (istm.org).
Healthy Travels!
© 2003 Alan Spira M.D., DTM & H, FRSTM
The
Travel Medicine Center
131 North Robertson Blvd.
Beverly Hills, CA 90211
USA
310.360.1331 phone 310.360.1333 fax
Document Date: Revised, January 23, 2003
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