Why this matters: A resurgence in travel could lead to more cases.
The United States eradicated malaria decades ago, but so did the global about 250 million cases of malaria According to the World Health Organization, in 2021, the vast majority will be in Africa. The CDC said that before the COVID-19 pandemic, there were about 2,000 cases of malaria reported each year in the United States, almost all of which were from people who contracted the disease abroad. (Pregnant women can transmit the parasite to their babies, and the disease can also be spread through blood transfusions, although such occurrences are rare in the United States, according to the CDC. The country commonly sees this.) One case related to blood transfusion Every two years, the agency says.)
But when infected people in other countries return to the United States, local mosquitoes can feed on them and pass on the parasites. “These kinds of things happen all the time,” said biologist Colin Carlson of Georgetown University. “That’s what you would expect in a country that has achieved disease eradication: from time to time you will have reinfection, and a little bit of local transmission.”
Dr. Carlson said he does not think the country is on the verge of a major malaria outbreak. But the CDC said that as international travel increases this summer, the number of imported malaria cases could increase.
Background: The role of climate change is unclear.
Malaria is most common in warmer climates, and a recent study by Dr. Carlson found that some Anopheles mosquitoes have already adapted to climate change.
But it’s hard to say whether the new US cases are linked to climate change. It’s possible that weather conditions in the southern United States have become more favorable for malaria transmission, but the region was already warm enough for the disease to spread, Dr. Carlson said.
Still, climate may be contributing to these cases in more subtle ways, he said, perhaps by making the disease more prevalent in places Americans are traveling to. This could result in more imported cases, giving the parasite more opportunities to spread within the United States.
“If travelers are returning from places that are on the front lines of climate impacts, malaria transmission will be more likely,” Dr Carlson said. “We live in a connected world, and the effects of climate change in other countries can be health problems in our country.”
What next: Officials will monitor more cases.
CDC is working with state health officials to investigate the new cases. The agency said authorities are actively monitoring for more possible cases and working to control local mosquito populations.
People can protect yourself By using insect repellent, wearing long pants and long sleeves, and using window screens, among other precautions. The CDC said that people who plan to travel should research the risk of malaria in their destinations and talk to their doctors about preventive measures.