United States: Malaria is back in the country and scientists want to understand why

United States: Malaria is back in the country and scientists want to understand why

For at least four people in Florida — and one in Texas — it has been Diagnosed with malaria Which they must have contracted near where they live because, according to health officials, none of them had traveled outside the United States or their home state. Because of the unusual discovery, infectious disease specialists are asking many questions: Who else could be sick? Will local doctors be able to identify the problem?

malaria It’s not entirely new to the United States: Every year, about 2,000 residents contract it but always because of it They have traveled to a place where the disease is endemicShe was bitten by an infected mosquito and fell ill when she got home. Locally contracted malaria is extremely rare. It arises from a chain of transmission that likely begins with an American mosquito biting a tourist, migrant or refugee who was in an infected country. Which carries the infection in the blood. Then the insect transmits it by biting another person. But in the United States, this has not happened since 2003.

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According to the World Health Organization, approx 247 million cases of malaria And in each Mosquitoes are just a vector (There is a difference to this from Covid-19 and other diseases.) Humans are the host Natural disease mosquitoes carry it between people. So when experts know someone has been diagnosed and can be sure they haven’t traveled, the first question is: Who else was injured and not reported?

Good and bad news

“If there are five cases right now, that means there are a lot more infected mosquitoes and there may be more people infected than we know.”he claims Ross BoyceMD, a physician and assistant professor at the University of North Carolina at Chapel Hill School of Medicine who directs a malaria research program in Uganda,

The five people identified by health authorities in Sarasota County on Florida’s west coast and Cameron County on the southern tip of Texas have He has already received treatment and is recoveringAccording to the Centers for Disease Control and Prevention. In both regions, mosquitoes were captured, analyzed and in control areas They spray pesticides to demolish the local colonies.

These mechanisms are familiar in parts of the United States, where they were instrumental in the defense against the Zika epidemic that swept through North and South America in 2016 and reached Brownsville, Texas, in Cameron County, at the end of the same year. Florida has battled an outbreak of dengue fever, another mosquito-borne virus, for more than a decade after it took hold. Featured in Key West And the next step north to Miami.

But malaria has not been present consistently in the United States since it has been around It was eliminated in 1951in a campaign that led to the emergence of CD. (The agency was originally called Office of Malaria Control in War Zonestasked with minimizing the impact of disease on soldiers heading into World War II and on bases producing tanks and ships). For this reason, malaria experts fear that doctors, especially general practitioners, may not recognize it when they see it.

“malaria It often has non-descriptive symptomsYou have a fever or feel like you have the flu and not all doctors get there right away. When local transmission begins, clinicians need to keep this possibility in mind.” He claims Amy Bayan epidemiologist and assistant professor at the Yale School of Public Health, for an interview at a research center in Senegal.

If there is one good newsIn these recent discoveries, it is the parasite species that causes it. All five types of malaria parasites fall into the genus plasmodium And they all destroy red blood cells. But the species in these new cases are P. vivax, which are geographically distributed more widely, But it is often less deadlyfrom the prevailing form Plasmodium falciparum. However, the Vifax He continues to make people seriously ill and has an evolutionary stunt that sickle Does not have a. After the initial infection, it can lie dormant in the liver, causing no symptoms and not showing up on blood tests until activated: the person who thinks they are cured He may not know that he is still a danger to others.

The dangers posed by dengue, Zika, and also the West Nile virus prompted Americans to do so Think about the impact of climate change on diseases spread by mosquitoes. The species that spread these viruses – Aedes aegypti Dengue, Zika and more somewhat Colex As for the West Nile – they seem to be expanding their ranges, and severe storms and warm nights brought on by climate change could make areas more mosquito-friendly than before.

But malaria is transmitted by species of a different genus, anophelesThese already exist in most parts of the United States. climate change him Regions expanded in which they spread Anopheles In Africa and some modeling studies indicate that climate change It will increase the risk in more countries where mosquitoes already existfor example by promoting greater numbers of insects or by extending the number of months that mosquitoes live.

However, in the United States, the places where these new cases occurred are the same places where malaria is found It would infect people before it was eliminated locally; In these places there are already mosquitoes anopheles And it’s already hot enough to support them. So perhaps climate change hasn’t made these people more vulnerable than before.

This makes it even more important for municipalities in risk areas to adopt strict control measures. It is an important request. In the United States, mosquito control is local and very partial: some Florida cities might use the equivalent of a small air force of spray planes, but elsewhere in the South, funding is scarce. “I hope this is a wake-up call that resources are needed for vector surveillance and control. So you report bedbugs before you have a human caseBoyce explains.

Prevention at home and abroad

definitely, Preventing the spread of malaria in the United States is simple, but not easy. It’s simple, because it is only necessary that people do not bring infection into the country. But it is not easy, because any malaria prevention plan You must take into accountHuge number of persons entering the United States from endemic areas, such as tourists, economic migrants, asylum seekers and refugees. The human movement spreads malaria and has done so since prehistoric times. This motion is not likely to be stopped, but the risk of infection can be reduced.

Travelers can prevent malaria by taking one dose daily or weekly drugs Which kills the parasite because it circulates in the blood or multiplies in the liver. However, almost all antimalarials have some side effects, from minor side effects like upset stomach and headache to lucid dreams and flashes of psychosis, and so people often give up on them. with the “Boom on “Voyage Voyages” After covid-19, more Americans than ever are venturing into endemic tropics and, without protection, can take home malaria as an “involuntary souvenir.”

“We already have 2,000 cases a year, and many of them are because people are not taking precautions.”he claims Joanna Dailya senior malaria researcher, professor at Albert Einstein College of Medicine and physician at Montefiore Health System. “If people are traveling to endemic areas, please see a travel clinic and take antimalarials. This may prevent malaria here in the United States.”.

This article originally appeared on Wired USA.

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