A serial killer lurks behind a series of secured doors in a building on Johns Hopkins University’s East Baltimore campus.

Actually, 50,000 killers. That’s how many mosquitoes researchers are breeding every week in the Malaria Research Institute in an effort to understand the inner workings of the world’s deadliest animal.

The goal is to learn how to fend off bites, develop more effective treatments and vaccines, and even build a “better mosquito” — a genetically modified variant that could someday be released into the wild to replace mosquitoes that transmit parasites, viruses and other dangers.

The work that goes back a quarter century is taking on new importance now that malaria — thought eliminated from the United States in the 1950s — has again been detected. There were 10 cases of locally acquired malaria last year, including one in Maryland that public health officials couldn’t fully explain.

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“We have vectors for malaria here, so we can have malaria here,” said Conor McMeniman, an assistant professor of molecular microbiology and immunology in Hopkins’ Bloomberg School of Public Health. “We’ll be watching what happens in the next couple of years.”

The insectary at the Johns Hopkins Bloomberg School of Public Health houses thousands of mosquitos in efforts to study malaria.
The insectary at the Johns Hopkins Bloomberg School of Public Health houses thousands of mosquitoes for research on malaria and other diseases they spread. (Kaitlin Newman/The Baltimore Banner)
Transgenic mosquito pupa, or larvae, are shown under a microscope at the Johns Hopkins Bloomberg School of Public Health insectary. This stage of life is akin to the chrysalis stage of a butterfly. They have a fluorescent glow to mark which pupa have been genetically modified. This protein comes from jellyfish.
Genetically modified larvae are shown under a microscope at the Johns Hopkins Bloomberg School of Public Health insectary. This stage of life is akin to the chrysalis stage of a butterfly. (Kaitlin Newman/The Baltimore Banner)
Doctor Conor McMeniman studies transgenic mosquitos under a microscope.
Doctor Conor McMeniman studies mosquitoes under a microscope that have been injected with a protein from coral or jellyfish, giving them a fluorescent glow. (Kaitlin Newman/The Baltimore Banner)

The vectors are anopheles mosquitoes that transmit malaria, said McMeniman on a recent tour of the Hopkins institute’s insectary to increase awareness on World Malaria Day. The mosquitoes, in need of a blood meal to make eggs, spread malaria when they bite a person infected with the parasite. Then they bite another person, passing it on.

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Mosquitos at the Johns Hopkins Bloomberg School of Public Health Malaria Research Institute Insectary.
Mosquitoes bred at the insectary are injected with malaria and other deadly diseases so researchers can study how the illnesses spread. (Kaitlin Newman/The Baltimore Banner)

With so few Americans infected at any given time, the cycle largely broke decades ago.

But researchers say the U.S.-borne cases might be explained by more post-coronavirus pandemic travelers bringing malaria home, and even climate change. More rain means more mosquitoes, and warmer temperatures could mean a longer mosquito season, explained a panel of experts from Hopkins, the University of Maryland, and the state health departments in New York and Maryland.

The experts said there are challenges as some parasites have become resistant to drugs, and mosquitoes also have become resistant to insecticides. Another issue in the United States is that few have been keeping tabs on the anopheles mosquitoes since malaria was deemed eliminated in the United States.

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Mosquitoes transmit more than malaria, but it’s this parasite that is one of the world’s biggest public health threats.Malaria infects close to 250 million a year and kills more than 600,000, many of them children under 5, according to a report last year from the World Health Organization.

Most deaths are in African countries, a tragic yet, until recently, distant problem for most Americans. There are usually 2,000 to 2,500 malaria cases in the United States linked to people who visit areas where malaria is endemic.

The locally acquired Maryland case last year involved a strain called Plasmodium falciparum, which is most common in sub-Saharan Africa and is among the most deadly. It was a different strain from the cases in other states, making it all the more vexing. The patient, who lives in the Washington, D.C., suburbs, recovered after being hospitalized.

It’s critical that medical providers recognize the symptoms early and don’t confuse them with other maladies, said one of the panelists, Dr. David Blythe, director of the Maryland Department of Health’s Infectious Disease Epidemiology and Outbreak Response Bureau. Symptoms include high fever, body aches, diarrhea and vomiting. Providers also need to alert the state health department of suspected cases so there can be proper testing.

“The system worked like it was supposed to,” he said of the one malaria case. “But it’s important to make sure everyone is aware.”

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He said that includes medical providers but also travelers, who can get preventive medications. For people who visit mostly their backyards and other local outdoor spaces, experts also say they should use repellent with DEET, cover exposed skin with clothing, close doors and windows or use screens, and empty standing water weekly to prevent mosquitoes from laying eggs.

Back in the Hopkins insectary, Chris Kizito, the facility manager, demonstrated how researchers breed the mosquitoes in trays of water. They are fed mouse blood to encourage them to produce eggs. They grow into larvae and feed on cat food. They mature and are given sucrose, a sugar, to keep them going for more than a month.

Entomologist Christopher Kizito, the facility manager at Johns Hopkins Bloomberg School of Public Health Malaria Research Institute Insectary, explains the process the mosquitos go through.
Entomologist Christopher Kizito, the facility manager at Johns Hopkins Bloomberg School of Public Health Malaria Research Institute Insectary, grew up in Uganda and suffered from malaria as a child. Most deaths from malaria are in African countries, many of them children under 5. (Kaitlin Newman/The Baltimore Banner)
Entomologist Christopher Kizito, the facility manager at Johns Hopkins Bloomberg School of Public Health Malaria Research Institute Insectary, holds a cup of mosquito eggs.
Kizito holds a cup of mosquito eggs, which the insects lay in standing water. (Kaitlin Newman/The Baltimore Banner)
Mosquitos and their eggs, the little black specks, at the Johns Hopkins Bloomberg School of Public Health Malaria Research Institute Insectary.
Mosquitoes and their eggs, the little black specks, are carefully cultivated in the insectary. (Kaitlin Newman/The Baltimore Banner)

Researchers study the insect’s development and determine what smells attract them to humans. They inject them with malaria and a bunch of nasty viruses, including dengue, chikungunya and Zika.

Some mosquitoes are genetically modified in the lab in an attempt to understand the role of each gene and to potentially disrupt the mosquitoes’ ability to pass on diseases. As a safety measure, they are injected with a protein from coral or jellyfish so they glow and can be distinguished from other mosquitoes.

Kizito and McMeniman said there also are strict no-biting and no-escaping policies for the insectary, one of the largest in North America with 32 full-time faculty and 13 labs.

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Mature mosquitoes are vacuumed into boxes. (Kaitlin Newman/The Baltimore Banner)

Kizito shows some of the standard operating procedures, carefully replacing screening on water trays full of mosquitoes during their growth cycles and vacuuming mature critters with a hose to move them into boxes.

Kizito said he’d had malaria infections as a child in Uganda, and seeing the disease ravage other children has been a big motivator for his career in entomology.

“It knocks you down,” he said. “If you get drugs in time you feel better. If you don’t, it’s rough. A lot of kids die.”

Meredith Cohn

meredith.cohn@thebaltimorebanner.com

Meredith Cohn is a health and medicine reporter for The Baltimore Banner, covering the latest research, public health developments and other news. She has been covering the beat in Baltimore for more than two decades.

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