Deadly tropical disease spread by sandflies gains a foothold in US: new report

Doctors are sounding the alarm on a deadly tropical disease spreading into the US — it was once so rare that most doctors have never seen a single case of it.

But now, leishmaniasis — a potentially lethal disease spread by tiny sand flies — is endemic in the US. It used to be seen only in people who had traveled to tropical countries.

“Most doctors, if you ask them, ‘Is there leishmania in the US?’ They’ll say ‘no way’ or ‘What is that?’” Dr. Gideon Wasserberg, professor of disease ecology at the University of North Carolina at Greensboro, told CNN.

Sand flies are much smaller than mosquitoes — so small they can slip through most window screens — and spread the parasite that causes leishmaniasis by biting a person or animal.

“Sometimes you don’t even notice that you’ve been bitten,” said Dr. Mary Kamb, a medical epidemiologist at the Centers for Disease Control and Prevention.

Kamb presented evidence at this week’s annual meeting of the American Society of Tropical Medicine and Hygiene that leishmaniasis has now been found in people who haven’t traveled outside the country, proving that the disease is now part of living in the US.

A warming climate makes it likely that sand flies will continue to expand their territory, experts say, and spread diseases like leishmaniasis farther north.

The only cases of leishmaniasis in the US thus far have been reported from Texas — possibly because other states don’t require doctors to report the disease to public health officials — but sandflies can now be found as far north as New Jersey, Delaware and Ohio.

Other diseases once confined to the tropics are now creeping northward into the US: Malaria, for example, might now be endemic in places like Florida and Texas.

“If the average temperature increases in northern states, which is expected, then sand flies will be able to establish themselves there and then you only need the parasites to have transmission,” said Dr. Pedro Cecilio of the National Institutes of Health.

What is leishmaniasis?

There are two main types of leishmaniasis: the cutaneous form affects the skin, while visceral leishmaniasis affects internal organs and kills up to 20,000 people annually.

After a bite from an infected sand fly, people who develop symptoms (not everyone does) will have skin sores, bumps or lumps that may end up as ulcers with a raised edge and central crater.

Leishmaniasis, if caught early, can usually be treated with anti-parasitic medications. The skin sores typically heal on their own, even without treatment. But this can take months or even years, and the sores can leave ugly scars, according to the CDC.

People with visceral leishmaniasis usually have fever, weight loss, swelling of the spleen and liver and abnormal blood tests. If not treated, severe cases of visceral leishmaniasis are usually fatal.

Dogs carry leishmaniasis

One unusual means of spreading visceral leishmaniasis is man’s best friend: An estimated one million dogs are imported into the US, and they can be a means of spreading the disease to other animals — and to humans.

There is no human vaccine for leishmaniasis, but vaccines are available for dogs in Europe and Brazil.

“There’s been a slow trickle of [infected] dogs being imported into the US” from countries where visceral leishmaniasis is endemic, Christine Peterson, director of the Center for Emerging Infectious Diseases at the University of Iowa, told Live Science.

There have been past reports of visceral leishmaniasis-carrying dogs being imported to the US and Canada, and it’s known that some breeds can pass the parasite to their puppies during pregnancy.

The CDC advises people in regions with sand flies to avoid outdoor activities, especially from dusk to dawn, when sand flies are most active.

Also, minimize the amount of exposed skin, and apply insect repellent that contains the chemical DEET to exposed skin and under the ends of sleeves and pant legs.