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Malaria is a serious disease that causes a high
fever and chills. You can get it from a bite by an infected mosquito. Malaria
is rare in the United States. It is most often found in Africa, Southern Asia,
Central America, and South America.
Malaria is caused by a bite from a mosquito
infected with parasites. In very rare cases, people can get malaria
if they come into contact with infected blood. A developing fetus may get the disease from its mother. You cannot
get malaria just by being near a person who has the disease.
Most malaria infections
cause symptoms like the flu, such as a high fever, chills, and muscle pain.
Symptoms tend to come and go in cycles. Some types of malaria may cause more
serious problems, such as damage to the heart, lungs, kidneys, or brain. These types can
Your doctor will order a blood test to check for
the malaria parasite in your blood.
Medicines usually can treat the illness. But some
malaria parasites may survive because they are in your liver or they are
resistant to the medicine.
Get medical help
right away if you have been in an area where malaria is present, were exposed
to mosquitoes, and get symptoms that are like the flu. These include a high
fever, chills, and muscle pain.
You may be able to prevent malaria by taking
medicine before, during, and after travel to an area where malaria is present.
But using medicine to prevent malaria doesn't always work. This is partly due
to the parasites being resistant to some medicines in some parts of the
Learning about malaria:
A bite from a parasite-infected
malaria. There are five species of Plasmodium (P.) parasites that infect
Malaria is spread when an infected Anopheles mosquito bites
a person. This is the only type of mosquito that can spread malaria. The
mosquito becomes infected by biting an infected person and drawing blood that
contains the parasite. When that mosquito bites another person, that person
In the United States, people who develop malaria almost always got infected while traveling in parts of the world
where malaria is common. For more information, see the topic
Malaria can begin with flu-like symptoms. In the early stages, infection
from P. falciparum is similar to infection from
P. vivax, P. malariae, and
P. ovale. You may have no symptoms or symptoms that are
less severe if you are partially immune to malaria.
The time from the initial
malaria infection until symptoms appear (incubation
period) typically ranges from:2
Symptoms can appear in 7 days. And the time
between exposure and signs of illness may sometimes be as long as 8 to 10 months with
P. vivax and P. ovale.
The incubation period may be longer if you are taking medicine to prevent
infection (chemoprophylaxis) or because you have some
immunity due to previous infections.
In regions where malaria is present, people who get infected many times may have the disease but have few or no symptoms.3 Also, how bad malaria symptoms are can vary depending on your general health,
what kind of malaria parasite you have, and whether you still have your
In the early stages, malaria symptoms are sometimes similar to those of
many other infections caused by bacteria, viruses, or parasites. Symptoms may
Symptoms may appear in cycles. The time between episodes of
fever and other symptoms varies with the specific parasite you are infected
with. Episodes of symptoms may occur:
P. falciparum does not usually cause a regular, cyclic fever.
The cyclic pattern of malaria symptoms is due to the
life cycle of malaria parasites as they develop, reproduce, and are released from
the red blood cells and liver cells in the human body. This cycle of symptoms
is also one of the major signs that you are infected with malaria.
symptoms of malaria include:
In rare cases, malaria can lead to impaired function of
the brain or spinal cord, seizures, or loss of consciousness.
Infection with the P. falciparum parasite is
usually more serious and may become
other conditions with symptoms similar to a malaria
infection. It is important that you see your doctor to find out the cause of
When you're bitten by a
malaria-infected mosquito, the parasites that cause
malaria are released into your blood and infect your liver cells. The parasite
reproduces in the liver cells, which then burst open. This allows thousands of new
parasites to enter the bloodstream and infect red blood cells. The parasites
reproduce again in the blood cells, kill the blood cells, and then move to
other uninfected blood cells.
After the early stages,
life-threatening complications may develop rapidly with P. falciparum and P. knowlesi. If the infected person is not treated, serious complications or death can occur.
But you may recover in a week to a
month (or longer) after being infected with P. vivax,
P. malariae, or P. ovale, even without treatment.
Malaria can be a very serious disease for a
pregnant woman and her developing fetus, for people without a spleen, and for
young children. Medicine choices are limited for a pregnant woman or a
child. Infection with P. falciparum can lead to death
for a pregnant woman and her fetus. For these reasons, a pregnant woman should
not travel to an area where she could get P. falciparum
malaria. Visit the CDC website (www.cdc.gov/malaria/travelers/index.html) to find
out whether malaria is a problem in the country where you will be traveling.
Malaria caused by
P. falciparum may come back (recur) at irregular
intervals for up to 2 years if treatment is not complete.
caused by P. vivax and P. ovale
may recur at irregular intervals for up to 3 to 4 years, but medicine can prevent relapses.
can remain in the blood of an infected person for more than 30 years, usually
without causing any symptoms.
Risk factors (things that increase your
risk) for getting
Your risk of getting malaria depends on your age, history
of exposure to malaria, and whether you are pregnant. Most adults who have
lived in areas where malaria is present have developed partial immunity to
malaria because of previous infections and so almost never develop severe
disease. But young children who live in these areas and travelers to these
areas are especially at risk for malaria because they have not developed this
Pregnant women are more likely than nonpregnant women
to get severe malaria, because the immune system is suppressed during
Also, pregnant women,
young children, older adults, and people with other health problems are more
likely to have serious complications if they get malaria.
take measures to reduce the risk of malaria if you live in areas where the
disease is present or if you are traveling in these areas.
Malaria is more severe in people who have had their spleen removed
Call a doctor immediately if you have been in an area where
malaria is present, were exposed to mosquitoes, and
develop flu-like symptoms (such as fever, chills, headache, and nausea).
Watchful waiting is a wait-and-see approach. If
you get better on your own, you won't need treatment. If you get worse, you and
your doctor will decide what to do next.
Do not wait to call a
doctor if you think you have malaria. Call a doctor immediately.
For people who live for many years in countries where malaria is common
and have some immunity to malaria, watchful waiting is okay for mild malaria
symptoms. Flu-like symptoms may also be caused by many other diseases or health
conditions. Watchful waiting is not appropriate for most travelers. If you have
a question about your symptoms, call your doctor.
Health professionals who can check out
symptoms that may be caused by malaria include:
In the United States,
call the Centers for Disease Control and Prevention (CDC) toll-free at
1-800-232-4636 (1-800-CDC-INFO) or visit the CDC's malaria website
(www.cdc.gov/malaria) to receive the most current
information about malaria and appropriate travel precautions. Your doctor or
local health department may also have this information.
To prepare for your appointment, see the topic Making the Most of Your Appointment.
thick and thin blood smears to find out whether
malaria-causing parasites are in your blood.
These tests should be done if you have been in a region where malaria is present,
you were exposed to mosquitoes, and you have flu-like symptoms.
A blood test that can diagnose malaria rapidly also is available. If this rapid test indicates a person has malaria, the results are usually confirmed with a blood smear.
Other useful tests that may be done
Other tests being developed to diagnose malaria
include genetic tests or other blood tests that highlight parasites by using
special stains. These experimental tests are not as easy to do and are not as
frequently used as blood smears.
In the United
States, malaria is an infectious disease that must be reported to the local or
state health department.
Medicine can prevent
malaria and is needed to treat the disease. Several
things influence the choice of medicine, including:
Malaria is rare in the United States. But it
is widespread in other parts of the world. Find out about the risk for malaria
before you travel internationally. The most accurate information about malaria
risk and medicine resistance in specific countries is from the Centers for
Disease Control and Prevention (CDC) and the World Health Organization (WHO).
If you have malaria, medicine choice is based on:
If you have been in an area where malaria occurs, were
exposed to mosquitoes, and have flu-like symptoms, but tests do not show the
malaria parasite in your blood, the tests should be repeated 3 or 4 times to
confirm that you do not have a malaria infection. During treatment,
tests are repeated to follow the course of the infection and to check whether
the number of parasites is decreasing.
Your age and health
condition are important factors in selecting a medicine to prevent or treat
children, people who are very old, people who have
other health problems, and those who did not take medicine to prevent
malaria infection require special consideration.
malaria involves protecting yourself against mosquito
bites and taking antimalarial medicines. But public health officials strongly
recommend that young children and pregnant women avoid traveling to areas where
malaria is common.
The most current information about
malaria is available from the Centers for Disease Control and Prevention (CDC)
and the World Health Organization (WHO). If you are planning international
travel, you can learn about the risk of malaria in that geographic area and the
medicines recommended to prevent infection by contacting:
To prevent mosquito bites,
follow these guidelines:
Other steps that may be helpful in reducing the risk of
malaria include using air conditioning and electric fans, wearing protective
clothing, using aerosol insecticides in your house, and taking certain
The selection of
medicines to prevent malaria depends on the
geographic region where you may be exposed to malaria
and your health condition (such as being pregnant, being elderly or young,
being sick, or having immunity or resistance to malaria, or having allergies or
sensitivity to the medicine).
If you are going to a location
where malaria is present, it is very important to take preventive medicines and
to follow the correct schedule for taking them. The majority of people who
become infected with malaria do not take preventive malaria medicines or do not
follow the correct dosing schedule.
Scientists are studying
malaria vaccines to see whether the vaccines are
effectively preventing malaria infection. But no vaccine has been approved to prevent malaria.1, 5 Work continues on improving vaccines for preventing
If you plan to travel in remote areas
malaria is present, it is very important to take
preventive medicines and to follow the correct schedule for taking them. The
majority of people who become infected with malaria did not take preventive
malaria medicines or did not follow the correct dosing schedule.
If you are going to areas where there is no medical care available, you
can get medicine before you leave and carry it with you while you travel. Your
doctor will give you instructions on how to use the medicine if you should
develop malaria symptoms. This is a temporary measure until you can get medical
care. Seek medical care as soon as possible (ideally within 24 hours).
The most current
information about the prevention and treatment of malaria is from the Centers
for Disease Control and Prevention (CDC) and the World Health Organization
(WHO). Contact the CDC at its toll-free phone number (1-800-232-4636) or website (www.cdc.gov/malaria). The WHO website is www.who.int/malaria.
You can take medicines called
antimalarials to prevent and treat
malaria. Malaria is a very serious disease, and its
presence in many regions of the world is well known. So if you are traveling to an area where malaria is present, it is important to reduce the risk of infection by taking medicine before you travel, while you are in the area, and after you return home. Which medicine you take is based on:
It is important to know which species of parasite is
present, because serious complications may develop rapidly in a person who is
infected with Plasmodium (P.) falciparum. Drug treatment
is based on:
During malaria treatment, your doctor may
do daily blood smears to follow the course of the infection. Most
medicines for malaria are ones you take by mouth. But you might get intravenous
(IV) medicines if there are complications or your condition gets worse. If there
are no complications, your fever will clear in 36 to 48 hours. And most
parasites will disappear from your blood within 2 or 3 days.
The medicines used may change as malaria parasites develop resistance and as new medicines are developed.
There are several medicines for preventing and treating
A doctor or local health department can consult the CDC for
specific treatment guidelines for your travel destination. Standard medicines
for preventing malaria include:
When a malaria infection is caused by
resistant strains of P. falciparum or P. vivax, treatment may be more
difficult. When treatment with chloroquine does not work, you must take other
medicines. These medicines may include:
You can get antimalarials intravenously (IV) if you are unable to take pills. IV delivery is also used for severe malaria. In the United States,
quinidine is the medicine typically used in these
have recurring flu-like symptoms for years after the initial malaria
infection. Relapses from infection of P. vivax or
P. ovale are the most common and can be prevented by
transfusions may be considered for treating severe cases of
Exchange blood transfusion is the quickest way to remove
parasites. This procedure involves withdrawing blood from you at the same time
that donor blood is being injected. During this exchange, the amount of blood
in your body stays constant. Quinine is given by needle into a vein
(intravenously) at the same time as the blood transfusion. Parasite density is
checked every 12 hours until it is less than 1%.6
Suh KN, et al. (2004). Malaria. Canadian Medical Association Journal, 170(11):
American Public Health Association (2008). Malaria. In
DL Heymann, ed., Control of Communicable Diseases Manual, 19th ed., pp. 373–393. Washington, DC: American Public Health
Fairhurst RM, Wellems TE (2010). Plasmodium species (malaria). In GL Mandell et al., eds., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 7th ed., vol. 2, pp. 3437–3462. Philadelphia: Churchill Livingstone Elsevier.
Asidi A, et al. (2012). Loss of household protection from use of insecticide-treated nets against pyrethroid-resistant mosquitoes, Benin. Emerging Infectious Diseases, 18(7): 1101–1106. Also available online: http://wwwnc.cdc.gov/eid/article/18/7/12-0218_article.htm.
Croft AM (2010). Malaria: Prevention in travellers,
search date November 2009. Online version of Clinical Evidence (7).
Centers for Disease Control and Prevention (2011).
Treatment of malaria (guidelines for clinicians).
Other Works Consulted
Day N (2008). Malaria. In M Eddleston et al., eds.,
Oxford Handbook of Tropical Medicine, 3rd ed., pp.
31–65. Oxford: Oxford University Press.
Freedman DO (2008). Malaria prevention in short-term
travelers. New England Journal of Medicine, 359(6):
Current as of:
June 4, 2014
E. Gregory Thompson, MD - Internal Medicine & W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
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