Florida and Texas are seeing some locally acquired cases of malaria – the first spread of the mosquito-transmitted disease inside the US in 20 years, officials warn in a health alert.
Active surveillance for more cases is continuing, the Centres for Disease Control says.
The risk of catching malaria in the US remains extremely low, it says.
All five patients – four in Florida, one in Texas – have now had treatment.
Malaria is caused by being bitten by an infected mosquito. People cannot catch it from each other. But the insects catch it from infected people – and the cycle continues.
It is common in large areas of Africa, Asia and Central and South America but not the US.
However, Anopheles mosquitoes, found throughout many parts of the US, can transmit malaria, if they have fed on an infected person.
The risk is higher in areas where:
- the climate means insects survive during most of the year
- travellers from malaria-endemic areas are found
Infected people can suffer fever, sweats and chills. Malaria is an emergency and must be treated quickly with drugs to kill the parasite that causes the infection.
Using insect repellent and covering up can help protect against mosquito bites.
The CDC says it is working with the Florida and Texas health departments and those recently diagnosed and treated “are improving”.
US doctors are being advised to consider malaria in any person with an unexplained fever, regardless of international travel history, particularly if they have visited or live in the affected areas of Florida or Texas.
Florida has issued a mosquito-borne illness alert after cases were discovered in Sarasota County and Manatee County, warning residents to drain standing water where mosquitoes can breed and wear long-sleeved shirts and pants.
Mosquito-borne diseases becoming increasing risk in Europe
Mosquitoes that carry viruses like dengue and chikungunya have moved into new parts of Europe, increasing the risk of illness, top experts warn.
European scientists say more frequent heatwaves and flooding, and longer, warmer summers, have created more favourable conditions for the bugs.
They are calling for better measures to control and protect against mosquitoes.
Without these, more illness and deaths from mosquito-borne diseases are likely, they say.
The report, by the European Centre for Disease Prevention and Control (ECDC), tracks the spread of different species of mosquitoes that can carry and transmit a number different of viruses to humans.
These include dengue and Zika – which can cause a range of symptoms such as fevers and muscle aches, and in the worst cases make people extremely ill.
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The ECDC report suggests this year, the Aedes albopictus mosquito (known to carry dengue and chikungunya) “established” itself in 13 countries in Europe – meaning it has developed a self-sustaining population that is reproducing – compared with eight European countries a decade ago.
Meanwhile, last year, Aedes aegypti, which can spread diseases such as yellow fever, Zika and West Nile virus, became established in Cyprus, and scientists warn it may continue to spread to other countries.
According to the report, in 2022:
- there were 1,133 human cases of West Nile virus and 92 deaths, with the majority of cases acquired in Europe – the highest since the peak of about 1,548 cases in 2018
- cases were reported in Italy, Greece, Romania, Germany, Hungary, Croatia, Austria, France, Spain, Slovakia and Bulgaria
- 71 cases of locally acquired dengue were recorded in mainland Europe – equivalent to the total number reported between 2010 and 2021
- cases of dengue were seen in France and Spain
Andrea Ammon, ECDC director, said: “In recent years we have seen a geographical spread of invasive mosquito species to previously unaffected areas in the EU/EEA.
“If this continues, we can expect to see more cases and possibly deaths from diseases such as dengue, chikungunya and West Nile fever.
“Efforts need to focus on ways to control mosquito populations, enhancing surveillance and enforcing personal protective measures.”