Malaria

Malaria is a disease caused by a parasite. The parasite is transmitted to humans through the bites of infected mosquitoes. People who have malaria usually feel very sick, with a high fever and shaking chills. Each year, approximately 210 million people are infected with malaria, and about 440,000 people die from the disease. Most of the people who die from the disease are young children in Africa.

While the disease is uncommon in temperate climates, malaria is still common in tropical and subtropical countries. World health officials are trying to reduce the incidence of malaria by distributing bed nets to help protect people from mosquito bites as they sleep. Scientists around the world are working to develop a vaccine to prevent malaria.

If you're traveling to locations where malaria is common, take steps to prevent mosquito bites by wearing protective clothing, using insect repellants and sleeping under treated mosquito nets. Depending on the area you are visiting and your individual risk factors for infection, you may also want to take preventive medicine before, during and after your trip. Many malaria parasites are now resistant to the most common drugs used to treat the disease.

Malaria
Common symptoms of malaria include:

A malaria infection is generally characterized by the following signs and symptoms:

  • Fever
  • Chills
  • Headache
  • Nausea and vomiting
  • Muscle pain and fatigue

Other signs and symptoms may include:

  • Sweating
  • Chest or abdominal pain
  • Cough

Some people who have malaria experience cycles of malaria "attacks." An attack usually starts with shivering and chills, followed by a high fever, followed by sweating and a return to normal temperature. Malaria signs and symptoms typically begin within a few weeks after being bitten by an infected mosquito. However, some types of malaria parasites can lie dormant in your body for up to a year.

Causes

Malaria is caused by a type of microscopic parasite. The parasite is transmitted to humans most commonly through mosquito bites.

Mosquito transmission cycle

  • Uninfected mosquito. A mosquito becomes infected by feeding on a person who has malaria.
  • Transmission of parasite. If this mosquito bites you in the future, it can transmit malaria parasites to you.
  • In the liver. Once the parasites enter your body, they travel to your liver — where some types can lie dormant for as long as a year.
  • Into the bloodstream. When the parasites mature, they leave the liver and infect your red blood cells. This is when people typically develop malaria symptoms.
  • On to the next person. If an uninfected mosquito bites you at this point in the cycle, it will become infected with your malaria parasites and can spread them to the other people it bites.

Other modes of transmission

Because the parasites that cause malaria affect red blood cells, people can also catch malaria from exposure to infected blood, including:

  • From mother to unborn child
  • Through blood transfusions
  • By sharing needles used to inject drugs

Risk factors:

The biggest risk factor for developing malaria is to live in or to visit areas where the disease is common. There are many different varieties of malaria parasites. The variety that causes the most serious complications is most commonly found in:

  • African countries south of the Sahara Desert
  • The Asian subcontinent
  • New Guinea, the Dominican Republic and Haiti

Risks of more-severe disease

People at increased risk of serious disease include:

  • Young children and infants
  • Older adults
  • Travelers coming from areas with no malaria
  • Pregnant women and their unborn children

Poverty, lack of knowledge, and little or no access to health care also contribute to malaria deaths worldwide.

Diagnosis

To diagnose malaria, your doctor will likely review your medical history, conduct a physical exam and order blood tests. Blood tests are the only way to confirm a malaria diagnosis. Certain blood tests can help your doctor by showing:

  • The presence of the parasite in the blood, to confirm that you have malaria
  • Which type of malaria parasite is causing your symptoms
  • If your infection is caused by a parasite resistant to certain drugs

Other blood tests help determine whether the disease is causing any serious complications.

Some blood tests can take several days to complete, while others can produce results in less than 15 minutes.

Treatment

Malaria is treated with prescription drugs to kill the parasite. The types of drugs and the length of treatment will vary, depending on:

  • Which type of malaria parasite you have
  • The severity of your symptoms
  • Your age
  • Whether you're pregnant

Medication:

The most common antimalarial drugs include:

  • Artemisinin-based combination therapies (ACTs). ACTs are, in many cases, the first line treatment for malaria. There are several different types of ACTs. Examples include artemether-lumefantrine (Coartem) and artesunate-amodiaquine. Each ACT is a combination of two or more drugs that work against the malaria parasite in different ways.
  • Chloroquine phosphate. Chloroquine is the preferred treatment for any parasite that is sensitive to the drug. But in many parts of the world, the parasites that cause malaria are resistant to chloroquine, and the drug is no longer an effective treatment.

Other common antimalarial drugs include:

  • Combination of atovaquone and proguanil (Malarone)
  • Quinine sulfate (Qualaquin) with doxycycline (Vibramycin, Monodox, others)
  • Mefloquine
  • Primaquine phosphate