Covering the mosquito-borne disease malaria

By Bara Vaida

Malaria has staged a comeback in U.S. hospitals, where about 1,700 people are hospitalized annually with the disease, according to NPR. All of those hospitalized had become infected overseas, but as the climate warms and more people travel, public health experts worry about the resurgence of malaria.

The disease is transmitted by the Anopheles mosquito. Malaria existed in the U.S. until the early 1950s, when an aggressive public health campaign, including the use of insecticides, drainage ditches and window screens, helped to eliminate the disease.

But the disease remains rampant in much of world. The World Health Organization estimates that 219 million people were infected with malaria in 2017 and 435,000 people, mostly young children, died for the disease. About 70% of the malaria transmission is occurring in 11 countries: 10 in Africa, plus India.

The disease is also occurring in more urban areas in Africa, like Djibouti and Ethiopia, where international travel is prevalent – hence the concern that more people may show up in U.S. hospitals with malaria.

Malaria has been on the planet for thousands of years. Mosquitos carrying the parasite lurked in the smelly marshes and swamps of ancient Rome, which is how it got its name “mal aria,” or bad air in Italian.

It is a complicated disease to treat and to prevent because it has several forms and doesn’t always behave the same way in each person.

The disease is caused when an Anopheles mosquito carrying a Plasmodium parasite bites a person. There are four kinds of Plasmodium parasites that are most dangerous to humans, and at least one kind causes swift illness and potential death without treatment.

When a mosquito with malaria bites a human, the parasite enters the bloodstream and heads to the liver where it can reproduce explosively. The parasites feed off liver and red blood cells, and can lead to death without treatment. Symptoms usually take several weeks to appear. Sometimes, the parasite decides not to reproduce and remains in the liver where it lies dormant for years, and then becomes active, sickening the individual.

The Plasmodium parasite and the Anopheles mosquito are also wily organisms that have developed resistance to elimination efforts. After World War II, the WHO launched an effort to eliminate malaria worldwide with insecticides, agriculture programs to eliminate standing water where mosquitos breed, bed nets to prevent mosquitos from feeding on humans at night and treating malaria patients so that they can’t pass on the disease to others.

But malaria parasites have evolved and developed resistance to two of the most powerful treatments for malaria – chloroquine and quinine – and the mosquitos developed resistance to insecticides.

With increasing deforestation, urban populations, international travel, shifts in agriculture practices and climate change, malaria could worsen. With climate change, more areas of the world are hospitable to the Anopheles mosquito and the warmer temperature speeds up the development of the parasite in mosquitos so that it can spread to humans.

An effective vaccine for the four kinds of parasite that sicken humans has remained elusive. The first malaria vaccine is being rolled out in Ghana, Kenya and Malawi this year, though the vaccine is only about 40% effective. GlaxoSmithKline developed the vaccine over 32 years, at the cost of $700 million. The Bill & Melinda Gates Foundation, the WHO and Gavi, the vaccine alliance, helped to support its development. Time will tell how effective the vaccine will be.

Though U.S.-based journalists may not see malaria as a local threat, public health experts urge journalists to get up to speed on covering the disease, because it is a global threat and it is showing up in more often in U.S. hospitals.

Story ideas to consider:

Has there been a case of malaria in your local hospital? Is your hospital prepared if someone does show up with the disease?
Has anyone in your community been diagnosed with malaria and survived to tell as a story about its impact on the body?
Are there any researchers in your community working on malaria vaccines, diagnostic tools or new insecticides for killing mosquitos?
How might climate change increase the risks of mosquito-borne diseases? There are many mosquito-borne diseases, malaria, Zika, dengue fever, yellow fever, Rift Valley Fever are just a few of those diseases, and as the climate warms, the geography of mosquito habitats will change.
How can travelers learn where malaria is endemic and what can they do to prevent getting sick?