Brain-swelling disease carried by mosquitos is surging with highest numbers so far in 22 years

The US is seeing surging numbers of a virus that can cause life-threatening swelling in and around the brain and spinal cord.And cases will continue to climb, as August has historically been the month where most cases appear.This summer, the country saw the earliest start of the West Nile virus season — and the most cases in early summer since 2004.On average over the last 22 years, only about 10 cases are reported by the end of June.This year, the CDC counted 48.Cases have shot up since then.

As of Wednesday, total cases in the US reached 143.As much as 69% of them had an infection that spread to their nervous system.An estimated 80% of people with the virus won’t see symptoms or don’t have severe enough symptoms to go to a doctor.Most people who do get symptoms get a sudden fever and may experience fatigue, headache, muscle aches, joint pain, a skin rash, vomiting or diarrhea.About 1% of people experience neuroinvasive disease, or an infection that reaches the nervous system.

This requires immediate hospitalization.The virus could cause meningitis, or swelling of the membrane around the brain and spinal cord.People with meningitis get a sudden high fever, headache, stiff neck, and are sensitive to light.

They might also be confused or struggle to stay awake and be nauseous or vomit.People with similar symptoms might have a more severe condition — encephalitis, or swelling of the brain itself.Someone with encephalitis might also be agitated or get hallucinations, experience movement changes like twitching and tremors, and have trouble balancing.Acute flaccid myelitis (AFM) might happen at the same time as meningitis or encephalitis.

AFM affects the spinal cord, causing sudden muscle weakness in the arms or legs, loss of reflexes, facial drooping, and in severe cases, respiratory failure.This condition mainly affects young children.People who catch West Nile virus are more likely to develop serious neuroinvasive disease if they’re older or are immunoc...