TITLE: 'A warmer, sicker world': Mosquitoes carrying deadly diseases are on an unstoppable march across the US
https://www.bbc.com/future/article/20240925-why-mosquitoes-are-thriving-in-a-warmer-world
EXCERPT: Once rarely seen outside of East Africa and parts of the Middle East, West Nile virus is establishing an increasing hold in New York and more broadly across the US. In 2023, the virus was detected in more than 1,100 mosquito pools, mostly in Queens. To date in 2024, cases of West Nile fever have been detected in 39 states. An estimated 70-80% of West Nile infections are very slight or entirely asymptomatic, but severe infections can lead to permanent neurological complications.
An even more concerning trend is the rise of Eastern equine encephalitis (EEE), another mosquito-borne virus which is far more dangerous, with a reported 30% fatality rate. EEE was first identified as a public health threat back in 1938, but over the past 20 years, sporadic outbreaks in the north-east of the US have reoccurred with increasing frequency, with cases appearing steadily further north.
While EEE infections are thankfully still rare, the largest US outbreak in recent history took place in 2019, with a record 38 cases detected across the country. In 2024, a total of 10 EEE cases have been reported to date across six states, leading to mosquito spraying regimes in Massachusetts, where the most cases were, to prevent infection.
According to infectious disease experts, unusual patterns with mosquito-borne pathogens are becoming the norm. Earlier in September 2024, a man in New Hampshire was reported by his family to have been hospitalised with not one but three mosquito-borne illnesses at the same time: West Nile fever, EEE and St Louis encephalitis.
"What we're seeing more and more is people infected with multiple mosquito-borne diseases at the same time," says Chloé Lahondère, a biologist who studies blood-sucking insects at Virginia Tech.
Within the US, and around the globe, mosquito-borne diseases are popping up in increasingly atypical places. "Last year, we had locally acquired cases of malaria in the US for the first time in 20 years," says Desiree LaBeaud, a professor of paediatrics and infectious disease at Stanford University.
Locally acquired dengue fever has also been detected in California and Arizona. Meanwhile, record numbers of dengue cases have been reported across Europe while unprecedented deadly outbreaks have occurred in Peru.
Much of this is related to shifting climate patterns, which are allowing various mosquito populations that carry these viruses, such as various sub-species of the Aedes genus of mosquitoes and the species Culex coronator, to spread into new areas. As temperatures rise, mosquitoes can invade and thrive in habitats which once represented hostile environments. Since it was first detected in Louisiana in 2004, C. coronator has spread to almost of the south-eastern states, bringing diseases such as West Nile and St Louis encephalitis, while other mosquito species are finding that they can comfortably survive even further north.
"People have been surprised by Aedes-borne diseases like dengue popping up in California," says Sadie Ryan, a professor in medical geography at the University of Florida. "But once they examined all the mosquito surveillance data, they were finding these species in traps even quite [far] north in the state, which hadn't been seen before. They're not very well established there yet, but it's a warning."
TITLE: Four more health care workers reported illnesses after caring for bird flu case in Missouri
https://www.statnews.com/2024/09/27/bird-flu-missouri-four-more-healthcare-workers/
EXCERPTS: An investigation into the still unexplained human H5N1 bird flu infection in Missouri has turned up four additional health care workers who developed mild respiratory illness symptoms after caring for the patient in hospital in August, the Centers for Disease Control and Prevention reported on Friday.
It is not clear if any of these people were actually infected with H5N1; they were not tested at the time when they were ill. But the fact that they became ill after treating this patient raises the specter of person-to-person spread of the virus — a possibility that flu experts say needs further exploration. Testing their blood for antibodies to H5N1 should answer the question.
“CDC continues to closely monitor available data from influenza surveillance systems, particularly in affected states, and there has been no sign of unusual influenza activity in people, including in Missouri,” the agency said in the update, posted to its website.
The CDC continues to characterize the risk posed to the general public by the H5N1 outbreak as “low.”
This marks the third time that Missouri has revealed that it had found health workers who had flu-like illness after treating the unnamed H5N1 patient, who was hospitalized on Aug. 22. No details have been released about where in Missouri this took place, nor is it known how long the patient — who has recovered — was in hospital.
To date a total of seven people who were in contact with the confirmed case have been identified as having been ill — a household member and six health care workers. One of the health workers tested negative for influenza when he or she was ill.
The fact that the Missouri Department of Health and Senior Services is still finding such individuals weeks after the H5N1 patient was released from hospital is raising concerns about the rigor of the investigation that the state is running. The CDC cannot send investigators to a state unless its help is requested, and that hasn’t happened.
The Missouri case is one of 14 that have been detected in the U.S. this year, while the country has been in the grips of an H5N1 outbreak in dairy cattle that was first recognized in late March.
As of Friday, 239 herds in 14 states have tested positive for H5N1, though that is believed to be an underestimate of the true scope of the outbreak. Many farmers have refused to test their animals and few states have forced the issue. Exceptions are Colorado, which is doing bulk tank testing on dairy farms, and California, which is doing bulk tank testing of farms that are located close to or have interactions with affected dairies. Since the start of the outbreak, Colorado has found 64 infected herds. California, which declared its first positive herd in late August, has to date confirmed 41 affected farms.
TITLE: Experiment confirms that bird flu in the US is spread by milking procedures
https://english.elpais.com/health/2024-09-25/experiment-confirms-that-bird-flu-in-the-us-is-spread-by-milking-procedures.html
EXCERPTS: American and German scientists experimentally infected calves and dairy cows in a level 3 security laboratory to determine the transmission route of the highly pathogenic avian influenza, which is affecting animals on 231 farms in 14 U.S. states. The results confirm that the H5N1 virus accumulates in the udders and milk of cows, and is probably being transmitted by industrial milking systems.
American and German scientists experimentally infected calves and dairy cows in a level 3 security laboratory to determine the transmission route of the highly pathogenic avian influenza, which is affecting animals on 231 farms in 14 U.S. states. The results confirm that the H5N1 virus accumulates in the udders and milk of cows, and is probably being transmitted by industrial milking systems.
The study also infected dairy cows with a variant of H5N1 isolated from wild birds in Europe. The animals also became ill, showing that the American variant is not the only one capable of causing a large epidemic in cattle. The symptoms were so severe that some animals had to be euthanized early. Although the experiment cannot exactly reproduce the conditions found on farms, its results are consistent with the fatality rate of up to 5% of animals observed on livestock farms, the authors explain.
The origin of this epidemic is probably a single jump of H5N1 from a wild bird to a cow late last year or early this year, the study says. The movement of cattle between states is believed to have been responsible for the spread of the virus, which circulated for weeks without being detected.
Juergen Richt, a researcher at Kansas State University, where the study was conducted, told EL PAÍS: “Our experiments show that the virus spreads mainly through milking and probably through milking equipment.” “It seems that the replication of the virus in cows is limited to the mammary glands. It is worrying that H5N1 continues to be transmitted between dairy cows, because it may allow it to adapt even more,” he added.