2023-10-20 20:17:00
FRIDAY, Oct. 20, 2023 (HealthDay News) — A potentially deadly mosquito-borne infection may be more prevalent than previously thought, U.S. health officials report.
Named the Cache Valley virus after the area of Utah where it was first discovered in 1956, it has caused seven serious infections nationwide. But it could have infected up to 18% of the population, according to an expert from the US Centers for Disease Control and Prevention (CDC).
“We don’t know much about it, there have only been seven documented cases,” said CDC research microbiologist Amanda Calvert. Of these, three died and the others have had lasting effects, she said.
In all seven people, the virus caused an infection of the brain called encephalitis or an infection of the membranes that cover the brain and spinal cord, called meningitis, Calvert said. All of the patients had conditions that affected their immune system, which appears to be the reason they developed a serious infection.
Calvert mentioned that the last known case was in a patient who contracted it through an infected blood transfusion.
Most people who contract the virus have mild or no symptoms, he added. Symptoms are nonspecific and may include fever, headache, nausea, vomiting, fatigue, and rash.
There is no known specific treatment for the virus. Care consists of relieving symptoms with pain relievers.
Cache Valley virus is mainly seen in sheep. It causes stillbirths and congenital defects in lambs. Whether the virus can cause birth defects in humans is unknown, Calvert said.
The virus is not contagious and can only be spread by the bite of an infected mosquito, he said.
It is not even known which mosquitoes transmit it.
To learn more about the virus, the CDC has developed a new test to quickly identify antibodies in the blood. The agency is now validating the test and hopes to have it available to state health departments in the near future, Calvert added.
The hope is that the new test will allow for broader surveillance to determine whether recent infections are an indication of a growing threat.
The research was scheduled to be presented Thursday at the American Society of Tropical Medicine and Hygiene meeting in Chicago. Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.
“We don’t know much about it,” Calvert said. “So we don’t yet know if it is a growing public health threat, but everyone should always be aware of protecting themselves and their loved ones from mosquito and tick bites.”
He offered these tips:
“Before you go out, make sure you put on bug spray,” Calvert said. “Always wear loose-fitting clothing, and you can treat your clothing with permethrin as well to prevent insect bites.”
He said people who have compromised immune systems or are taking medications that compromise their immune system should be particularly careful during the warmer months to protect themselves from mosquito and tick bites.
Dr. Bruce Farber, an infectious disease specialist at Northwell Health in Manhasset, NY, said the Cache Valley virus does not appear to be a serious threat to most people.
“It illustrates one more thing that everyone knows now, which is that more and more viruses are zoonotic, which means that whether it’s COVID or this virus, or West Nile virus, or eastern or western equine or in St. Louis, they all tend to have reservoirs in animals,” he said. “Clearly, for me, the biggest threat by far would be avian influenza.”
Farber said there are many more serious health risks than the Cache Valley virus.
“There are so many landmines we can step on, so from a practical standpoint, it’s much more important to buckle up and treat your hypertension,” he advised.
He said many viruses circulating are not even known to doctors, so the “vast majority” of viral encephalitis cases have gone undiagnosed. Farber said doctors should be aware of the Cache Valley virus when faced with an unexplained case of encephalitis.
More information
For more information about Cache Valley virus, visit the US Centers for Disease Control and Prevention.
SOURCES: Amanda Calvert, PhD, research microbiologist, US Centers for Disease Control and Prevention, Fort Collins, Colo.; Bruce Farber, MD, infectious disease specialist, Northwell Health, Manhasset, NY; presentation, meeting of the American Society of Tropical Medicine and Hygiene, Chicago, October 19, 2023.
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