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Emerging Threat: Skin Infections in the US Linked to Tropical Parasite Spread by Sand Flies


Заголовок: "Rising Threat: Sand Flies in the US Transmitting Leishmaniasis, a Silent Skin Menace"

Text: In the realm of blood-sucking insects, move over mosquitoes; there's a new contender that demands Americans' attention — the sand fly. These diminutive tan insects, about a quarter of the size of their mosquito counterparts, thrive in warm, rural, and forested areas. While notorious for transmitting a parasitic single-celled organism responsible for the infectious disease leishmaniasis in other parts of the world, they've now set their sights on the United States.

Operating under the cover of darkness, these minuscule sand flies pose a unique challenge as they can easily slip through conventional mosquito nets on tents or window screens. Dr. Mary Kamb, a medical epidemiologist at the US Centers for Disease Control and Prevention in Atlanta, emphasizes the inconspicuous nature of their bites, stating, "Sometimes you don't even notice that you've been bitten."

Alarmingly, the CDC has identified cases of leishmaniasis in patients who claim to have never traveled outside the United States. A groundbreaking study, presented at the annual meeting of the American Society of Tropical Medicine and Hygiene, details the genetic analysis of tissue samples collected from these patients. Strikingly, these individuals exhibited leishmaniasis skin infections, marked by small bumps evolving into ulcerous sores days to weeks post-sand fly bites.

Dr. Kamb elucidates, "People could be asymptomatic and not develop anything, but when people are symptomatic, they develop ulcers on their skin and sometimes it starts like a little tiny volcano with a crater in it." While these sores aren't typically painful due to the parasite disabling nerves in the skin, they often scar and can be disfiguring, especially if located on a person's face.

The insidious nature of leishmaniasis doesn't end with skin infections; it can also infiltrate internal organs, including the liver, spleen, and bone marrow. The more severe form, visceral leishmaniasis, though not thought to be transmitted within the United States, poses a fatal threat if left untreated, often acquired through travel to tropical countries.

Most skin samples in the CDC study originated from Texas, currently the sole US state mandating doctors to report leishmaniasis cases. However, a 2021 research review reveals locally acquired cases in southeast Oklahoma, signaling the potential for the infection's wider reach. As we confront this emerging threat, understanding and vigilance become our allies in safeguarding against this silent skin menace.

Заголовок: "Beyond Borders: The Unseen Threat of Locally Acquired Leishmaniasis in the United States"

Text: In a surprising revelation, approximately six cases of leishmaniasis skin infections are annually reported in non-travelers across the United States, shedding light on an under-acknowledged public health concern. Dr. Luiz Oliveira, a staff scientist at the National Institutes of Health, underscores the shift, stating, "It's not just a traveler's disease anymore." Despite the World Health Organization categorizing leishmaniasis as endemic in the U.S., widespread awareness among both the public and medical professionals remains limited.

The threat extends beyond leishmaniasis, with a locally acquired malaria case recently reported in Arkansas, signaling an evolving landscape of infectious diseases within the country. Sand flies, carriers of the parasite responsible for leishmaniasis, have been identified in various southern and southwestern states. The expansion of their habitat, influenced by climate changes, has led some species of these biting flies to venture as far north as Delaware, New Jersey, Ohio, and Maryland. While it remains uncertain whether sand flies in these states have transmitted infections to humans, the potential risk looms.

Dr. Pedro Cecilio, a postdoctoral researcher at the NIH specializing in leishmaniasis transmission, emphasizes the correlation between rising temperatures in northern states and the establishment of sand flies. "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," warns Dr. Cecilio.

The revelations emerge from a comprehensive study presented at the annual meeting of the American Society of Tropical Medicine and Hygiene in Chicago. Researchers meticulously analyzed over 2,100 skin samples submitted to the CDC between 2005 and 2019, representing all 50 states, Puerto Rico, and the Virgin Islands. Among these, approximately half tested positive for leishmaniasis. Astonishingly, 86 positive samples were from patients with no travel history, highlighting the emergence of locally transmitted cases.

The most prevalent parasite among non-travelers was identified as Leishmania mexicana, with the CDC detecting two distinct genotypes. One genotype, named CCC, dominated nearly 94% of non-traveler infections, suggesting a potential endemic nature within the United States. This unforeseen development raises urgent questions about the unrecognized spread of leishmaniasis and the need for heightened vigilance in combating this stealthy, locally acquired threat.

Заголовок: "Unveiling the Silent Threat: Leishmaniasis Transmission in the U.S. Confirmed by Recent Study"

Text: In a groundbreaking development, Dr. Gideon Wasserberg, a distinguished professor of disease ecology and medical entomology at the University of North Carolina at Greensboro, sheds light on the concerning transmission of leishmaniasis in the United States. Although not directly involved in the recent research, Wasserberg acknowledges the study's significance in confirming suspicions held by entomologists for the past 5 to 10 years.

The study, which reveals the transmission of a species of leishmania within the U.S., showcases the complex interplay between sand flies, the parasitic leishmania, and their unsuspecting hosts. Wasserberg notes that in addition to the previously identified mexicana species, two other types of leishmania have been reported in patients with no recent travel history outside the United States. Intriguingly, Wasserberg suggests that rats may serve as carriers of the parasite. When sand flies bite infected rats, they become vectors for the leishmania parasite, capable of transmitting it to humans.

While there's much to be learned about the geographical spread of leishmaniasis by sand flies in the U.S., Wasserberg urges caution, especially in warm, rural areas. Offering practical advice, he recommends the use of bug sprays containing DEET as sand flies are repelled by them. Additionally, treating camping equipment and clothing with permethrin can provide added protection by eliminating sand flies.

Wasserberg emphasizes the importance of seeking medical attention for new skin sores that persist after a bug bite. Leishmaniasis treatment involves a month-long course with medications like amphotericin B, an antifungal drug approved by the FDA for treating leishmaniasis. Acknowledging the low awareness of leishmaniasis among U.S. doctors, Wasserberg commends the recent study for bringing attention to a disease that has long been under the radar.

As the silent threat of leishmaniasis becomes clearer, Wasserberg encourages proactive measures, underscoring the significance of public awareness, early detection, and informed medical responses to curb the spread of this emerging health concern in the United States.

In conclusion, the recent study on leishmaniasis transmission in the United States, as discussed by Dr. Gideon Wasserberg, illuminates a previously underestimated public health concern. The findings provide solid confirmation that a species of leishmania is now being transmitted within the country, aligning with suspicions held by entomologists over the past decade. Notably, the study reveals the presence of leishmania species in patients who have not recently traveled abroad, hinting at potential local transmission.

Dr. Wasserberg's insights into the role of rats as carriers of the leishmania parasite, transmitted to humans through sand fly bites, add a new dimension to understanding the dynamics of this disease. The complexity of the transmission cycle emphasizes the need for increased awareness and research to comprehend the geographical spread of leishmaniasis in the U.S.

The practical recommendations provided by Wasserberg underscore the importance of proactive measures, especially in warm, rural areas. Bug sprays containing DEET and permethrin-treated camping equipment and clothing are suggested as effective preventive measures against sand fly bites. Additionally, early medical attention is emphasized for individuals experiencing persistent skin sores after bug bites, as prompt diagnosis and treatment are crucial in managing leishmaniasis.

The study serves as a wake-up call, revealing a gap in awareness among U.S. doctors regarding leishmaniasis. Dr. Wasserberg's commendation of the study reflects the urgent need for increased education within the medical community and the general public. As the silent threat of leishmaniasis becomes more apparent, fostering awareness, early detection, and comprehensive medical responses are essential in mitigating the potential impact of this emerging health issue in the United States.