PROTECTING YOURSELF AGAINST MALARIA IS IMPERATIVE
ON A TRIP TO SOUTHERN AFRICA
HERE'S WHAT YOU SHOULD KNOW
by John Langone
A dreaded word coined in 1690 by Italian physician Francesco
Torti. He based it on the Italian malaria, or bad air - allusion
to the belief that noxious marsh gases were behind the often deadly
Today we know that malaria is caused by parasites transmitted
by mosquitoes. But anti-malarial drugs are still not 100 percent
effective, mosquitoes are becoming increasingly resistant to insect
repellents and insecticides, and a malaria vaccine has not yet
been developed. Moreover, it's residents of Africa who suffer
from malaria the most-90 percent of the annual 2.1 million malaria-induced
deaths occur there.
"However, there is not as much malaria in southern Africa
because of longstanding programs for hitting mosquito-breeding
sites," says Dr. Michele Barry, professor of medicine at
the Yale University School of Medicine and a staff member of its
Health and International Travelers Clinic. Indeed, the major cities-Harare,
Bulawayo, Johannesburg, and Cape Town-are malaria-free. "But
there are malaria trouble spots," continues Barry, "including
Zimbabwe; the Mozambique border parks, such as Kruger National
Park; and around Victoria Falls. In these places you have to be
This is also true for some of the other major areas of interest
to visitors: Ovamboland and the Caprivi Strip in northern Namibia;
the Okavango Delta in northwestern Botswana; the Zambezi River
Valley in northern Zimbabwe; and game parks and rural areas in
northern, eastern, and western low-altitude areas of Northern
Transvaal, Province of Northwest, Gauteng, and Mpumalanga in South
Africa. In short, the real risk is in rural regions and game parks.
Peak malaria seasons vary from country to country within southern
Africa but are generally highest during and right after the rainy
season (November to May, peaking between February and April),
as mosquitoes require water to breed. However, it's important
to remember that malaria isn't seasonal.
"The prevalence of Anopheles gambiae-the mosquito capable
of carrying malaria-depends on local breeding conditions and varies
with rainfall," explains Dr. William Trager, a parasitologist
at Rockefeller University in New York. "In temperate zones
mosquitoes hibernate in winter and transmit actively in warm weather.
In the tropics mosquitoes are around most of the time, and so
are infected people. Mosquitoes draw blood from them and pass
on the infection when they bite someone else. So the potential
to pick it up is always there."
There are 60-odd types of mosquitoes that can transmit malaria,
which is actually caused by parasites carried within the female
insect's body. When the mosquito bites, she injects the parasites
into the victim's bloodstream. One thing that makes the disease
particularly insidious is the fact that the parasites reproduce
within the mosquito's body. Thus one mosquito can infect many,
There are four malaria parasites that cause the disease in
humans: Plasmodium vivax, P. malariae, P. ovale, and P. falciparum.
The last named is the most dangerous and the one you're most likely
to encounter during your trip. "Ninety-six percent of the
malaria in Africa is Plasmodium falciparum," says Dr. Jay
Keystone of the Center for Travel and Tropical Medicine at Toronto
General Hospital, "and it's the deadliest."
You're most at risk for malaria-carrying mosquitoes in the
evening and at night, which are the only times the female anopheles
is normally active. Thus it's important to wear long-sleeved shirts
and long pants after dark and to use the mosquito netting that
game lodges provide
It's not easy to identify malaria symptoms because they can
easily be mistaken for those of other tropical diseases, such
as yellow and dengue fevers. In its early stages malaria mimics
the flu, causing fever, headache, chills, lethargy, and muscle
aches. If the disease persists untreated, non-flu-like symptoms
can appear, including mild jaundice and an enlarged liver; hypoglycemia,
or decreased blood glucose; and blackwater fever, which generally
occurs in patients with chronic falciparum malaria. Eventually
malaria can cause anemia, kidney failure, coma, and even death.
Prevention There are some powerful anti-malarial drugs available,
all of which must be taken on a strict regimen that begins before
travel, continues throughout, and lasts for several weeks after
returning home. None of the drugs, however, are 100 percent effective.
"There's no question that the drugs lower the risk dramatically,"
says Dr. Bradley Connor, medical director of Travel Health Services
in New York, "but there's also no worldwide consensus as
to what's best for malaria prevention." Even worse, the side
effects of the drugs can be extremely unpleasant.
Which drug you should take depends largely on which one your
body can tolerate. For trips to southern Africa, most doctors
prescribe mefloquine, also known as Lariam. Developed by the U.S.
Army, it is widely considered the most effective drug against
P. falciparum. It is taken once a week on the same day, starting
one week before entering the malarious area; while there; and
for four weeks after leaving. Some specialists caution that side
effects are likely, including gastrointestinal and sleep disturbances,
anxiety attacks, irritability, depression, nausea, and dizziness.
More severe effects-seizures, hallucinations, and psychosis-are
less common but are the reason travelers with a known hypersensitivity
to the drug, a history of epilepsy, or psychiatric disorders should
not take it. "Only one person in ten to thirteen thousand
experiences the most severe side effects," says Dr. Keystone,
"and only one in two hundred fifty to five hundred experiences
lesser ones. Just three percent of patients stop taking the drug
because of them."
For those who can't take , the Centers for Disease Control
(CDC) in Atlanta recommends doxycycline, an antibiotic. It is
taken every day for the same amount of time as mefloquine. Possible
side effects include stomach upset, esophagitis (inflammation
of the esophagus), vaginal yeast infection, and skin photosensitivity,
which can result in extreme sunburn. The drug cannot be used by
pregnant women, children under eight, and travelers with known
Chloroquine, the drug which replaced quinine in the 1940s
and is now marketed in the United States under the brand name
Aralen, is used in some areas of Africa-mainly Egypt and northern
Africa-because of its low cost. But it isn't recommended for trips
to southern Africa. "Chloroquine just doesn't work against
P. falciparum in most parts of Africa," says Dr. Keystone.
Dr. Trager concurs: "It doesn't work very much anymore against
P. falciparum. Vivax malaria still responds to it, despite some
reports of resistance, so there's some value in taking it if you're
going to parts of Africa where P. vivax is present." (That
means mainly the northeast part of the continent.)
Fansidar, or pyrimethamine sulfadoxine, a drug developed in
the 1960s, is also prescribed widely by doctors in Botswana and
Namibia because it is inexpensive. The CDC recommends it for self-treatment
if medical help is not available. But doctors with whom we spoke
say that, in general, self-treatment isn't recommended except
in the most dire situations. "If you come down with malaria
symptoms and can't get to medical care within forty-eight hours,"
says Keystone, "a single dose of Fansidar can be taken so
that you have time to get to a doctor. But it should not be used
as a preventative measure in general." The main risk from
a one-time dose of Fansidar is a severe skin reaction, but taking
it weekly can be fatal. It also shouldn't be taken by pregnant
women or anyone with a sulfur allergy.
Two combinations of anti-malarials are also sometimes prescribed.
One is chloroquine taken simultaneously each day with Proguanil,
or Paludrine. It isn't available in the United States but is obtainable
in Canada, Great Britain, Europe, and many African countries.
"Unfortunately there's a schism between British and U.S.
recommendations regarding this combination," says Dr. Connor.
"The CDC just doesn't believe that it offers adequate protection."
But even Dr. Keystone in Toronto is against it. "We advise
against this combination," he says. "Sure, it is safer
than mefloquine, only it doesn't work."
The other combination sometimes given is Malarone, a mixture
of proguanil and atovaquone, which has been licensed in Great
Britain. It is expected to be available in the United States and
Canada later this year but, according to some authorities, is
less effective than mefloquine alone. The real advantages are
that side effects are limited to upset stomach, itchiness, and
cough and that it must be taken daily for only one or two weeks.
A number of drugs are effective in treating malaria among
them primaquine, antibiotics, quinine, quinidine, and mefloquine.
Chloroquine is also used, but only if the malaria was acquired
in locales where parasites aren't resistant to the drug, which
excludes southern Africa. "The good thing about falciparum
malaria is that once it's been treated it usually never comes
back, unless you're reinfected," says Dr. Trager. "With
P. vivax this is not true-even after ordinary treatment, it may
relapse." An effective malaria vaccine has not yet been developed,
mainly because the complex parasite-mosquito relationship makes
it difficult for researchers to pinpoint the stage at which a
vaccine could intervene. Trager, the first to culture P. falciparum
in red blood cells (a key step in vaccine development), says that
back in 1976 he believed a vaccine would be available in 10 years.
"Here it is 1998," he says, "and it's turned out
to be more difficult than we thought."
Recently, however, a couple of promising new advances have
surfaced. One of them, the DNA vaccination, involves injecting
the DNA coding for a specific component of the malaria parasite
into the patient's body through a hypodermic needle or special
"gene gun." With the other, mosquitoes rendered genetically
incapable of carrying or transmitting malaria parasites would
be introduced into the environment to propagate. The problem,
according to Dr. Greg Lanzaro, a medical entomologist at the Center
for Tropical Diseases of the University of Texas Medical Branch
at Galveston, is that little is known about the mating behavior
of African mosquitoes.
Because a malaria infection can be life-threatening, the best
advice is to seek prompt medical assistance if you develop any
flu-like symptoms. "Here in the United States we don't appreciate
the magnitude of the disease," says Dr. Connor. "We
advise travelers to consider any fever as malaria until proven
This is true both during the trip and up to a year or more
after returning home. Says Dr. Barry: "Most times malaria
doesn't present itself when you're on holiday. It's usually when
you're back home. The majority of falciparum cases show up within
four months, vivax as much as years later. You really need a blood
test to tell." Because of the risk, travelers to malaria-prone
regions may not donate blood for three years after returning home.
Dr. Trager learned the hard way. Years ago he caught malaria
while in Nigeria. But he didn't come down with symptoms until
three years later. "P. vivax has dormant stages that weren't
affected by the chloroquine I was taking," he says. "Once
they're activated and infect red cells, that stage can be cured
with the drug. I think I hold the record for the longest period
risks and precautions