Miami, Fla., June 29, 2023. Miami-Dade County Mosquito Control Inspector Barrington Sanders sprays insecticide to kill adult mosquitoes.

Joe Raeder | Getty Images

U.S. public health officials say there is a risk locally transmitted malaria still at a low level in the country seven new cases Florida and Texas raised questions.

The Florida Department of Health said Friday two cases Locally infected malaria was reported in Sarasota County, bringing the state’s total to six cases.

Last week, the U.S. Centers for Disease Control and Prevention issued a national consultation In response to the initial four cases in Florida and one case in Texas, health care providers, local health departments, and the public are alerted to the possibility of: local malaria transmission.

The five patients “have been treated and are improving,” the CDC said. “Despite these cases, the risk of local malaria infection in the United States remains extremely low,” the agency added.

Seven people This is the first known case of ‘locally acquired’ malaria in the country country since 2003. That means the new cases of infection have nothing to do with foreign travel and appear to be transmitted by U.S. mosquitoes that carry the parasite that causes the disease.

malaria is a serious and potentially fatal disease that is usually spread through the bite of an infected person female anopheles, according to the CDC. It used to be endemic in the United States, which means it happened frequently and required widespread public health interventions.

In regions with warmer climates, where mosquitoes can survive most of the year, the risk of the disease is higher, the agency said.

The United States records approximately 2,000 cases of malaria each year, nearly all of which are acquired abroad rather than domestically.

New locally acquired cases should not raise alarm about widespread malaria in U.S., health experts say

But they also point to the importance of public vigilance at a time when climate change and a resurgence in international travel are increasingly exacerbating the spread of insect-borne diseases.

U.S. public health authorities and healthcare providers should also be prepared to step up malaria surveillance, the experts added.

Here’s what you need to know about cases of malaria in the United States, and why the risk of transmission remains low right now.

The cause of the case remains unclear

Miami, Fla., June 29, 2023. Miami-Dade County Mosquito Control Inspector Barrington Sanders sprays insecticide to kill adult mosquitoes.

Joe Raeder | Getty Images

Plasmodium vivax isn’t the deadliest form of malaria, but it’s harder to treat than other forms of malaria daniel parkerAssociate Professor of Population Health and Disease Prevention, UC Irvine Public Health Program.

Like other forms of malaria, Plasmodium vivax causes symptoms ranging from fever to difficulty breathing shortly after infection.

But the parasite can also lie dormant in the liver for days, months or years before reappearing in the blood and causing symptoms to return, Parker said. During its dormant period, P. vivax does not cause any symptoms and is undetectable in blood tests.

A resident of Florida or Texas may become infected with P. vivax abroad and return to the United States without realizing he has malaria because he has no symptoms. sadie ryanProfessor of Medical Geography at the University of Florida and director of the Florida Climate Institute.

When P. vivax becomes active again in the blood of local mosquitoes, the local mosquitoes may pick up malaria from unsuspecting travelers, and those mosquitoes may spread malaria to others in the area.

“It could be that a case of malaria came into the U.S. from somewhere else. Then the local mosquitoes infect that case and bite the local people,” Ryan said.

But experts say it is difficult to provide a definitive explanation without more details about the case.

Major U.S. gear equipped to contain local transmission

Sarasota, Fla., June 30, 2023. Health officials at the Sarasota County Mosquito Management Services study samples of malaria-causing Anopheles mosquitoes.

Chandan Khanna | AFP | Getty Images

UC Irvine’s Parker also said U.S. case-tracing protocols have made the country better prepared to contain the spread of the virus.

Health care providers must report all laboratory-confirmed cases of malaria to local or state health departments, making it easier to track potential spread of the disease, the CDC said.

Parker added that public health authorities also investigate cases after they are confirmed to better understand their origins, in a way “similar to the contact tracing efforts we are more used to now because of Covid-19. “

“The CDC was born in part out of our efforts to eliminate malaria. While I think we’ve overlooked some of the public health infrastructure, there are systems in place … to act quickly when a case is detected,” Parker said. said, referring to the Centers for Disease Control and Prevention Established in 1946.

The agency is announcing disease elimination 1951 in the United States.

But the U.S. toolkit for combating local malaria transmission is not perfect. Not all regions of the country have the local public health infrastructure to track and combat the disease, leaving local infections a step behind when cases spread.

The overall threat of malaria remains on the rise

A number of factors also make the country in general increasingly vulnerable to malaria, both locally and imported.

Climate change is causing changes in weather patterns that are exacerbating malaria. Dr Rajiv ChowdhuryGlobal Health Specialist at Florida International University. Global warming could lead to “increased mosquito migration and numbers” in areas of the country that were previously uninhabitable by Anopheles mosquitoes, he said.

Existing evidence suggests that rising temperatures can Increase growth rate and spread ability It is the parasite that causes malaria, Chaudhry added.

He also said climate change could lead to excess rainfall and rising sea levels in the U.S., creating more open spaces with waterlogged “effective breeding grounds” for mosquitoes.

It was not immediately clear whether the new local cases in Texas and Florida were linked to rising temperatures. Ryan of the Florida Climate Institute pointed out that the temperatures in these states are already hot enough for the disease to spread.

Choudhury agrees: “It’s really difficult to pinpoint a causal link between a particular case and the broader environmental changes that are taking place. We need more research to establish that link in the US.”

A CDC spokesperson told CNBC that “it is unclear whether the recently reported cases are due to climate change,” although changes in weather conditions do affect the spread of diseases such as malaria.

But a rebound in foreign travel this year could also increase the number of imported malaria cases in the country, the agency said.The agency emphasized last week “Concerns over potential rise” In those cases associated with an increase in summer international travel, those trips may return to pre-COVID levels.

Parker said the increase in international travel could lead to more imported and local infections.

“We may have more imported cases, and since we already have mosquitos locally, they may infect some and there may be more local transmission,” he said.

But he added: “I wouldn’t say I’m not too worried. As long as we stay vigilant.”

There are ways to manage risk

Public health authorities, healthcare providers and people can do more to control the country’s rising malaria risk, experts say.

Ryan said U.S. public health authorities should consider which areas of the country have become more suitable for malaria transmission and how those areas can build or strengthen the infrastructure needed to deal with the disease.

“That’s the area we need to focus on — thinking about where people should be anticipating this and what they can do to build the capacity needed to control the disease through vector control, public health messaging and other difficult issues, ” she says.

Stephen de Sakutin | AFP | Getty Images

Clinicians can also increase surveillance for the disease by considering a diagnosis of malaria in anyone with an unexplained fever, regardless of their travel history, the CDC said.

“Someone can get malaria and their doctor has never seen a case of malaria before. So they’re not used to dealing with this disease,” Parker said. “But public health agencies are releasing reports of local cases, so doctors should be wary of malaria .”

have no malaria vaccine available Not yet available to the U.S. public, but travelers can use antimalarial medications to prevent malaria infection during international travel. These drugs appear to be underutilized: only a quarter of travelers reported taking so-called drugs malaria prevention 2018.

It’s easy to mistake malaria for a common viral infection because the disease often causes flu-like symptoms.But the CDC says “The most important step” One step people can take if they are sick and have currently or recently traveled to an area with malaria is to see a doctor.

Early diagnosis ensures that malaria infections are treated before they become severe and life-threatening, the agency said.

“Now, we should not panic,” Choudhry said. “But we absolutely need to keep an eye on malaria and take these preparedness steps.”

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