A look at EEE, West Nile, malaria

Buzzing insects are more than annoying – they spread disease. When they bite and drink blood from a person or animal, they can also pick up viruses or germs. If they can continue to bite someone or something, they deposit the germ just under the skin.

People in some areas of Massachusetts have been warned to stay indoors when mosquitoes are most active after a rare case of eastern equine encephalitis was discovered and a New Hampshire resident recently died from an EEE infection. And Dr. Anthony Fauci, America’s former top infectious disease expert, was recently hospitalized after contracting the West Nile virus.

Both are nasty mosquito-borne diseases – though thankfully relatively rare.

The best way to avoid getting sick is, of course, to avoid being bitten, which means taking steps like using repellants, wearing long-sleeved clothes and long pants, and staying indoors when mosquitoes are out. Local health departments are also working to reduce mosquito numbers, including spraying neighborhoods with insecticide. Authorities in Massachusetts are using trucks and planes this week to spray vulnerable areas.

Here’s a look at some common — and less common — mosquito-borne diseases.

Most people infected with eastern equine encephalitis do not develop symptoms, but some may come down with fever or swelling of the brain, and about one-third of infected people die. There have been four cases of eastern equine encephalitis in the U.S. this year, according to the U.S. Centers for Disease Control and Prevention, with one each in Massachusetts, New Jersey, Vermont and Wisconsin. The worst year for the disease was 2019, with 38 cases. It is caused by a virus and is not very common around the world. The virus typically spreads in certain swamps, including red maple and white cedar swamps in Massachusetts.

About 2 in 10 people infected with West Nile virus develop symptoms, which can include fever and swelling of the brain. About 1 in 10 people who develop severe symptoms die. There have been 216 West Nile cases so far this year. West Nile virus was first reported in the US in 1999 in New York. It gradually spread throughout the country. In 2003, there were almost 10,000 cases.

Malaria infected nearly 250 million people globally in 2022 and killed more than 600,000, mostly children. It is caused by a parasite carried by mosquitoes and mainly infects people in tropical regions, especially Africa. A vaccination campaign has been launched in recent months that health officials hope will help reduce cases and deaths.

Also known as “bone-breaking fever” because it can be so painful, dengue is becoming more common. The World Health Organization says about half the world’s population is at risk of contracting the disease, and there are between 100 and 400 million infections each year. Not everyone has symptoms, which can include fever, severe headaches, and muscle and joint pain. Most U.S. cases are in people who have traveled to other countries, although the CDC says there have been about 2,600 locally acquired cases so far this year.