WASHINGTON — The world's deadliest animal can be squashed flat with a quick slap: It's the mosquito. The buzzing insects are more than annoying — they spread disease. When they bite and drink blood from a person or animal they can pick up viruses or germs too.

If they can go on to bite someone or something else, they deposit the germ right 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 Dr.

Anthony Fauci, the former top U.S. infectious disease expert, was recently hospitalized after he came down with West Nile virus.

Both are nasty diseases spread by mosquitoes — though thankfully they are relatively rare. The best way to avoid getting sick is of course to avoid getting bitten, which means taking steps like using repellent , wearing clothing with long sleeves and long pants and staying indoors when the mosquitoes are out. Local health departments also work 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 not so common — mosquito-borne diseases. Eastern equine encephalitis Most people infected with eastern equine encephalitis don't develop symptoms, but some can come down with fever or swelling of the brain and about one third of people infected die.

There have been three c.