A disfiguring parasitic infection, not unusual in the tropics, has found refuge in Texas and Oklahoma and is expanding its diversity to the United States. The parasite, Leishmania mexicana, is transmitted through tiny sandflies, which have now been discovered in Maryland, Delaware. and the state of New York, Jersey, and Ohio.
The researchers analyzed 2,100 skin samples. Of those, 1,222 had leishmania and, as expected, nearly all of the patients had traveled to endemic spaces (where the organism is commonly present), according to a recent report from the Centers for Disease Control and Prevention. However, 86 patients had not traveled, meaning they contracted the infection in the United States.
There are other strains of leishmania and they cause other types of diseases. The Mexican L discovered in Texas and Oklahoma causes the mildest form, cutaneous leishmania, which affects only the skin. It usually doesn’t require any treatment, explained Dr. David Freedman, professor emeritus of infectious diseases at UAB Birmingham. L brasiliensis (among other species) causes mucocutaneous leishmania, which I observed in my studies in Peru. At the time, he was being treated with a nasty antimonial antibiotic called Pentostam, with many side effects.
The most severe form of leishmania often occurs in the Middle East, Asia, and North Africa, but it can also occur in Latin America or elsewhere in immunocompromised people. The species L. donovani causes this systemic disease called kala-azar. It is visceral, infecting organs throughout the body, adding to the liver and spleen, and effects on death.
Everyone in the U. S. The U. S. skin is for a smoother skin shape.
The scientists also conducted special genetic studies on L mexicana in Texas and discovered two distinct genotypes. They called a type “CCC” and discovered it in 94% of non-travelers. While the “American strain” was discovered in samples such as 18 years ago, Freedman said Leishmania probably “existed forever. “He was aware of his presence in Texas in the 1980s. It was “under the CDC’s radar” because skin lesions regularly disappear without any remedy and because it is not a reportable disease.
Leishmania is transmitted through sandfly bites. Your general guests in the U. S. The U. S. rats are wood rats (not the usual Norway or city rats). Anne Straily (a veterinarian at the CDC) said in an email: “There is some debate about whether other wildlife, such as armadillos, or opossums, can also serve as reservoir hosts. In some cases, inflamed humans can transmit the parasite to sandflies.
For visceral leishmania, the most severe form, dogs are the main reservoir. Although dogs are a reservoir, no transmission of the parasite from dogs to humans has been identified. According to Anne Straily, a veterinarian at the CDC, L. infantum (the species responsible for the visceral form of the disease) “is already applied to some dogs in the United States, primarily hunting dogs. “
Many dogs are imported into the U. S. They are not expected to be rescued from Southeast Asia and pose a potential threat here. “No sandflies inflamed with L. infantum have been discovered in the United States, nor human cases of acquired visceral leishmaniasis caused by L. infantum has not been identified, not even among other people who were in contact with inflamed dogs,” Kamb and Cama said in an email interview.
An interdisciplinary group of runners, including CDC and public fitness veterinarians, has developed a new “operational threat assessment tool” to help veterinarians recognize and assess the dogs that pose the greatest threat. This tool was presented at the recent meeting of the American Society for Tropical Medicine and Hygiene and will be published in Emerging Infectious Diseases. Christine Petersen, director of the Center for Emerging Infectious Diseases at the University of Iowa, explained that most veterinarians are unfamiliar with this parasite by nature. The threat control tool helps them where the dog came here and what condition it will be in. For example, if a dog travels from Italy (or Southeast Asia) to Texas, there is some threat. But “if the dog comes from Sweden and goes to New Hampshire, the threat is very, very low and we’re not worried. “
There is also concern that a fifth of the 2. 7 million troops deployed in Iraq or Afghanistan show symptoms of asymptomatic visceral leishmania, adding parasites to their blood, for up to 10 years after their return. They may transmit their infection through insects. bites, pregnancy, transfusions, or intravenous drug use. A 27-month-old boy from North Dakota, who had never left the state, had an L-skin infection. donovani, which explains the visceral form of the disease (like L. infantum ). It is not known exactly how the transmission occurred; his mother from Nepal, but there is no evidence that he was tested.
Sandflies are much smaller than mosquitoes, so unless the nets are the right size, mosquito nets are less effective at preventing bites. Knowledge of their performance is mixed, but insecticide-treated nets have some advantages. They are used in rooms that are also sprayed with insecticides.
For use, DEET and permethrin are effective preventatives.
The first hurdle is getting doctors to diagnose leishmania. Many will probably never have noticed or suspected it. Even in a biopsy, this can go unnoticed because the organisms are so small and a special Giemsa stain is required. The species may not be known through its appearance, Freedman explained. Diagnosis is made periodically by molecular testing (PCR) at the CDC. Testing can now also be done at the University of Washington or the Walter Reed Army Research Institute, which are reserved for military personnel.
The other main factor is that there’s no need to file reports with the states, unless it’s Texas or the CDC. Without consistent reporting to the CDC, we have no ability to track how and where this happens.
The extent of climate change’s role in the spread of leishmania is still unknown, which explains why careful monitoring is needed.
Insecticide resistance is a concern. The Covid-19 pandemic has reduced investment in leishmaniasis programs and surveillance and led to fumigation.
We also want to make sure that the visceral type of leishmania is not endemic to the United States and is built up through sandflies that feed on inflamed dogs. This hasn’t happened yet (as far as we know), but it does require ongoing follow-up.
For many rare infections, it’s vital for doctors to thoroughly review exposure and history and have a maximum index of suspicion. It is also vital that doctors are informed on how to recognize cutaneous leishmaniasis and are aware that it can occur in other people. who have never led overseas.
The publication was updated with data from Christine Petersen related to the Risk Assessment Tool for Veterinarians.