A tropical disease is spreading in the US; here's everything you need to know

Cutaneous leishmaniasis, once referred to as a "traveller's disease," is becoming a more significant health concern in the southern United States. This tropical infection is transmitted through the bites of tiny sand flies that carry a single-celled parasite known as Leishmania, with various varieties that can infect mammals. Previously considered an ailment primarily found in tropical regions, India, and Central and South America, it has now been identified within the U.S. as an endemic disease, indicating a worrisome shift in its prevalence. The World Health Organization estimates that between 600,000 and one million new cases are reported each year.

Data from the Centers for Disease Control and Prevention (CDC) reveals that cases of cutaneous leishmaniasis have been detected in individuals with no travel history within the United States. This finding suggests that the disease is being transmitted locally, raising concerns among health experts. While Texas is the only state currently mandating national reporting of leishmaniasis cases, experts believe that the disease is underreported nationwide. Globally, the World Health Organization also acknowledges the underreporting of this disease, making it vital to raise awareness and enhance surveillance to address this growing public health issue.

Leishmaniasis can manifest in various forms, but the most common is cutaneous leishmaniasis, which causes skin sores. These sores usually appear a few weeks or months after being bitten by an infected sandfly. The sores can change in size and appearance over time, beginning as papules or nodules and evolving into ulcers with raised edges and central craters, sometimes covered by scabs or crusts. Although these sores are typically painless, they can become painful. In some cases, individuals may develop swollen glands near the sores, such as under the arm if the sores are on the arm or hand.

To diagnose leishmaniasis, clinical signs are combined with parasitological or serological tests. For cutaneous, serological tests have limited value, and the diagnosis is confirmed through clinical manifestations with parasitological tests. Treatment depends on factors like the type of disease, concurrent illnesses, parasite species, and geographic location. Leishmaniasis is treatable but not always curable, the parasite may not be completely eliminated from the body, leading to a risk of relapse, especially if the immune system becomes compromised.

Several factors increase the risk of leishmaniasis. Poverty and poor living conditions contribute to sandfly breeding and biting, while malnutrition weakens the body's ability to fight infection. Population mobility can lead to epidemics, especially when non-immune individuals move to high-transmission areas. Environmental changes, including urbanisation and climate variations, can impact the spread of the disease.

As per the US CDC, currently, there are no vaccines or drugs to prevent leishmaniasis. Travellers can reduce the risk of infection by protecting themselves from sandfly bites. Avoiding outdoor activities during peak sandfly activity (dusk to dawn) is advisable. When outdoors, wear long-sleeved shirts, long pants, socks, and apply insect repellent to exposed skin. Repellents containing DEET are often the most effective. Stay in well-screened or air-conditioned areas to keep sandflies at bay. Use insecticide to eliminate insects in living and sleeping areas. If not in a screened or air-conditioned environment, use bed nets, preferably treated with insecticide. The same treatment can be applied to screens, curtains, sheets, and clothing. These measures are essential to protect against leishmaniasis, especially when travelling to endemic areas.