Malaria Vaccine: An End to Fatal Mosquito Infections?

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Mosquito bites can result in malaria – could a new vaccine be the end of the dangers of getting bitten? Image by James Gathany, courtesy of the U.S. CDC

A new Malaria vaccine could save millions of lives, based on a recent study.

Mosquitoes carry malaria – a potentially-fatal disease that affected 26 million people worldwide in 2011, says the World Health Organization.

According to the Centers for Disease Control and Prevention there are about 1,500 cases of malaria in the United States every year; however, this is mainly due to travelers who are returning from countries where malaria transmissions occur – most malaria transmissions occur in the sub-Saharan Africa and South Asia.

Malaria is serious – but there is no vaccine to prevent this life-threatening disease… that is until recently.

Malaria Vaccine to Prevent Infection

Researchers make the vaccine, called  PfSPZ, by using samples of Plasmodium falciparum, the parasite that causes the malaria infection. These samples, although still live, were weakened by using radiation and then they were frozen.

The researchers gave the vaccine intravenously in either four or five doses. Three weeks after getting the vaccine, volunteers were bitten by mosquitoes that were infected with malaria.

Six volunteers received five doses of the vaccine – none of these volunteers contracted malaria.

Nine volunteers received four doses of the vaccine, only three of these volunteers contracted malaria.

The downside of the study is that is had only a small population of volunteers, and the vaccine needs to be able to ward off malaria for years, not just three weeks. However, the researchers didn’t set out to study how long the vaccine would be effective, what they set out to do was to develop a vaccine to protect people from malaria. In their study, although it was a small group, those who received the five doses of the vaccine were 100 percent protected.

Nets are treated with insecticide to prevent malaria. Photo by Presidents Mosquito Initiative a component of the U.S. Government's Global Health Initiative

Nets are treated with insecticide to prevent malaria. Photo by Presidents Mosquito Initiative a component of the U.S. Government’s Global Health Initiative

Severe Malaria Infection

Severe malaria occurs when infections are complicated by organ failure or abnormalities in the patient’s blood or metabolism. Manifestation of severe malaria include:

  • Cerebral malaria: abnormal behavior, seizures, coma, and other brain abnormalities. 
  • Severe anemia due to the destruction of red blood cells from the parasite
  • Acute respiratory distress which is an inflammatory response in the lungs that prevents oxygen exchange.
  • Hyperparasitemia occurs when more than five percent of the patient’s red blood cells are infected by the parasite.
  • Acute kidney failure in the patient.
  • Abnormalities in ability for the patient’s blood to form clots.
  • Metabolic acidosis can occur when there is excessive acid in the blood and tissue fluids.

Malaria can relapse even after months or years without any further symptoms, because the parasite has a dormant stage that can be reactivated.

Preventing Malaria

Controlling the mosquitoes is currently the main way to prevent the spread of malaria. According to the World Health Organization, there are two forms of vector control: Insecticide-treated nets and indoor spraying with insecticides. The insecticide nets are the preferred method and the WHO recommends that everyone at risk for contracting malaria sleep under these nets at night when mosquitoes are most likely to bite. Spraying insecticide indoors is good for three to six months, and DDT can be effective between nine to 12 months.

There are also medications, called antimalarial medications that can be given to travelers as well as chemoprophylaxis to prevent malaria among travelers. Other types of medications can be given to pregnant women who are at risk as well as infants.

Malaria Vaccine Could Save Lives

Malaria is a serious disease that can sometimes be fatal. The only protections we currently have against malaria infection are insect repellent, netting, and medications.  According to NPR, however, if all goes well with further testing, the vaccine could be ready for widespread use by late 2017 or early 2018.

Resources:

Seder,R., Chang, L., Enama1,M., et al. Protection Against Malaria by Intravenous Immunization with a Nonreplicating Sporozoite Vaccine. (2013). Science. Accessed August 9, 2013.

Centers for Disease Control and Prevention. About Malaria. (2012). Accessed August 8, 2013.

CNN News. U.S. reports a breakthrough in malaria vaccine. (2013). Accessed August 8, 2013.

NPR. Experimental vaccine shows promise in early trial. (2013). Accessed August 8, 2013.

World Health Organization. Malaria. Accessed August 8, 2013.

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