Don’t let the bed bugs bite.

If you live in the Baltimore-Washington metropolitan area, that might be difficult to do.

That’s because the two cities earned the distinction of topping Orkin’s top 50 bed bug cities list, with Baltimore taking the number one spot and Washington coming in second place.

The list is just the latest reminder that bed bug infestations have been on the rise in the United States for the past two decades.

However, although bed bugs are persistent pests, they are not considered a public health risk.

Experts say their bites might stink or itch, but they don’t transmit disease.

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But this information may not comfort the folks in Baltimore and Washington.

Or Chicago, New York, and Columbus, Ohio. They too appeared at the top of the list.

The five largest cities in the country — New York, Los Angeles, Chicago, Houston, and Philadelphia — appeared on the list.

The pest control company Orkin gathered its data between Dec. 1, 2015, and Nov. 30, 2016, basing its rankings on the number of residential and commercial bed bug treatments it performed in each city during this time period.

Read more: Get the facts on bed bug bites »

Not a disease risk

Although bed bugs can be a major annoyance and are tough to exterminate, they do not spread disease.

According to the , bed bugs “should not be considered as a medical or public health hazard.”

While they don’t spread disease, bed bug bites can cause irritation and in some cases, an allergic reaction.

It’s possible that the irritation caused by a bite could prompt excessive scratching, leading to a secondary skin infection.

Ron Harrison, Ph.D., Orkin entomologist, and director of technical services, told Healthline that only a small percentage of the population will notice when they’re initially bitten by a bed bug.

“We did a study at Orkin, showing that the first time you’re bitten, there’s a 3.7 percent chance you’ll react at the time of the bite, and then there’s another 1 percent chance that you’ll have a delayed reaction,” said Harrison. “So less than 5 percent of people in the United States — and this goes across gender and race — will react the first time they’re bitten. And then there’s a population — probably about 30 percent in this country — that never has a reaction to bed bug bites at all.”

Read more: Bed bugs may now be resistant to insecticides »

Making a comeback

Bed bugs have plagued humans for thousands of years, but they were mostly wiped out in the United States decades ago — only to come back with a vengeance.

A 2008 publication from the World Health Organization (WHO) noted that there were only two reported bed bug infestations in the United States in 1997. By 2004, infestations were reported in 40 states.

“We know that in the 40s and 50s and prior, bed bugs were a major issue,” said Harrison. “And we know that in the 50s and 60s, chemicals were available to everyone — at the local drug store you could pick up products that were highly effective against bed bugs. About the turn of the millennium, somewhere in that range, they were reintroduced — more than likely from Eastern Europe or Asia. And the products that were readily available to the common person were no longer available.”

International travel, bans on powerful pesticides, and pesticide resistance have all factored into the resurgence of bed bugs in the United States.

In a 2015 survey from the National Pest Management Association, 99 percent of pest professionals said they’d treated bed bugs in the past year — an increase compared with statistics from five, 10, and 15 years ago.

To fight the problem, the city of Chicago — ranked third on the Orkin list — passed a series of ordinances in 2013 aimed at curbing the spread of bed bugs. These rules include mandating that landlords and tenants make a concerted effort to document and deal with any infestations.

Read more: Indoor pesticide use linked to childhood cancers »

Banish the bugs

To keep your home free of bed bugs, it’s important to be able to recognize the signs of an infestation.

The bugs are tiny, wingless, reddish-brown insects that range in length from 1 millimeter to 7 millimeters.

Vigilance is the best way to stay one step ahead of the bugs, says Harrison.

“I believe that we should all be inspecting our beds every time we wash the sheets, so the one or two bed bugs that may get introduced are dealt with quickly, and then the treatment is relatively easy,” he said.

Harrison says that if you suspect you have bed bugs, or want to inspect a hotel room for the pests, it’s best to inspect the edges of the mattress, the area behind the headboard, and areas around nearby furniture to look for the fecal smears that bed bugs leave behind.

If you’re in a hotel room, Orkin recommends elevating your luggage, saying the safest place to put it is in the bathroom.

If there are signs of bed bugs, Harrison recommends calling in a professional to assess the situation.

“If you pull back your sheets and see a bed bug, that might be the only bed bug you have,” he said. “So therefore, to do a lot of pulling up things, changing things, may not be worth it. A professional can come very quickly and say, ‘You’ve got an infestation,’ ‘You’ve got hundreds,’ or ‘You’ve just got one.’ I would encourage folks to, first of all, collect the bed bug that you found and place it in a vial or bag and call the pest control company.”