Some of the roughly 1 million cases a year of the parasitic disease leishmaniasis don't fit with the standard definition of the disease--the patients have unusual symptoms and front-line medicines don't work. Now, researchers have discovered why many of these cases are so different--they're caused by parasites with distinct genetic variations. The finding, reported in PLOS Neglected Tropical Diseases, was made by studying patients in northeast Brazil but may hold true elsewhere around the world.
Leishmania impression smear. Courtesy of Michael Wunderli, Flickr
Some of the roughly 1 million cases a year of the parasitic disease leishmaniasis don't fit with the standard definition of the disease--the patients have unusual symptoms and front-line medicines don't work. Now, researchers have discovered why many of these cases are so different--they're caused by parasites with distinct genetic variations. The finding, reported in PLOS Neglected Tropical Diseases, was made by studying patients in northeast Brazil but may hold true elsewhere around the world.
Leishmaniasis is a parasitic disease caused by infection with Leishmania parasites, which are spread by sand flies in the tropics, subtropics, and southern Europe. Bites from flies carrying the parasite may turn into skin lesions which can become infected with bacteria. Brazil is one of six countries where 90 percent of new cases occur. However, a small percentage of these cases don't fit into the most commonly recognized subtypes of the cutaneous disease. Previously, researchers have attributed these atypical cases (ACL) to the patients themselves, who may have chronic diseases or be pregnant. However, many patients don't fit this pattern, suggesting there are other factors at play. Between 2005 and 2012, Luiz Henrique Guimarães, Albert Schriefer, of the Universidade Federal da Bahia in Brazil, and colleagues, followed 51 patients with ACL and 51 matched cutaneous leishmaniasis (CL) patients. The researchers collected not only clinical data, but blood and skin samples to study both the genetics of the parasite infecting each patient, as well as their body's immune response to the disease.
The team found that patients with ACL had significantly more lesions, particularly above the waist, than those with standard CL. Moreover, their disease typically lasted longer and was more likely to be resistant to antimony, the front-line treatment used in Brazil. While 98% of CL patients healed after one or two courses of the drug, only 35% of ACL patients were treated after two courses. The researchers went on to show that the ACL found in the northeast of Brazil is caused by a genetically distinct strain of Leishmania braziliensis; the parasites from 62.5% of ACL patients studied had genetic variations seen only in ACL. Finally, levels of inflammatory cytokines, produced by the immune system, were higher in ACL.
"Precise identification of ACL is important because it usually does not readily respond to drugs commonly used to treat leishmaniasis in Brazil, but readily responds to other treatment options available," the researchers write. "These findings may contribute to our understanding of the pathogenesis of ACL, and ultimately to a more logical approach to management of this and other unusual forms of [leishmaniasis]."
Reference: Guimarães LH, Queiroz A, Silva JA, Silva SC, Magalhães V, Lago EL, et al. (2016) Atypical Manifestations of Cutaneous Leishmaniasis in a Region Endemic for Leishmania braziliensis: Clinical, Immunological and Parasitological Aspects. PLoS Negl Trop Dis 10(12): e0005100. doi:10.1371/journal.pntd.0005100
Source: PLOS
Stay prepared and protected with Infection Control Today's newsletter, delivering essential updates, best practices, and expert insights for infection preventionists.
Reducing Hidden Risks: Why Sharps Injuries Still Go Unreported
July 18th 2025Despite being a well-known occupational hazard, sharps injuries continue to occur in health care facilities and are often underreported, underestimated, and inadequately addressed. A recent interview with sharps safety advocate Amanda Heitman, BSN, RN, CNOR, a perioperative educational consultant, reveals why change is overdue and what new tools and guidance can help.
New Study Explores Oral Vancomycin to Prevent C difficile Recurrence, But Questions Remain
July 17th 2025A new clinical trial explores the use of low-dose oral vancomycin to prevent Clostridioides difficile recurrence in high-risk patients taking antibiotics. While the data suggest a possible benefit, the findings stop short of statistical significance and raise red flags about vancomycin-resistant Enterococcus (VRE), underscoring the delicate balance between prevention and antimicrobial stewardship.
What Lies Beneath: Why Borescopes Are Essential for Verifying Surgical Instrument Cleanliness
July 16th 2025Despite their smooth, polished exteriors, surgical instruments often harbor dangerous contaminants deep inside their lumens. At the HSPA25 and APIC25 conferences, Cori L. Ofstead, MSPH, and her colleagues revealed why borescopes are an indispensable tool for sterile processing teams, offering the only reliable way to verify internal cleanliness and improve sterile processing effectiveness to prevent patient harm.
The Next Frontier in Infection Control: AI-Driven Operating Rooms
Published: July 15th 2025 | Updated: July 15th 2025Discover how AI-powered sensors, smart surveillance, and advanced analytics are revolutionizing infection prevention in the OR. Herman DeBoard, PhD, discusses how these technologies safeguard sterile fields, reduce SSIs, and help hospitals balance operational efficiency with patient safety.
Targeting Uncertainty: Why Pregnancy May Be the Best Time to Build Vaccine Confidence
July 15th 2025New national survey data reveal high uncertainty among pregnant individuals—especially first-time parents—about vaccinating their future children, underscoring the value of proactive engagement to strengthen infection prevention.