Epidemiology of the leishmaniases
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1Department of Immunology, Walter Reed Army Institute of Research, Washington, D.C., USA.
Abstract:
The leishmaniases are a group of zoonotic infections caused by protozoan parasites of the genus Leishmania. These infections produce a variety of different clinical diseases depending on the virulence or tropism of the parasite and differential host immune responses. Newly recognized clinical presentations, such as viscerotropic leishmaniasis in American military veterans of Operation Desert Storm, continue to challenge clinicians. Epidemics of classic visceral leishmaniasis leading to thousands of deaths are ongoing in Brazil, India, and the Sudan. Epidemics of localized cutaneous leishmaniasis are ongoing in many areas of South America, North Africa, and Central Asia. A marked increase in cases is often associated with an influx of nonimmune populations into newly cleared agricultural populations into newly cleared agricultural areas or population expansion into previously unsettled areas surrounding cities. The emergence of leishmaniasis as an important opportunistic infection in AIDS patients portends an ominous future as the HIV pandemic sweeps into the hyperendemic areas of South America, Africa, and the Indian subcontinent. Parenteral transmission via needle sharing in HIV coinfected individuals in Spain is an epidemiologically significant new mode of transmission. Finally, recent work has elucidated an enzootic transmission cycle involving L. mexicana in Texas.
Insights
Leishmaniases are zoonotic infections caused by Leishmania parasites, presenting diverse clinical forms and challenging global public health. Emerging transmission routes and opportunistic infections in immunocompromised individuals highlight ongoing concerns.
Area of Science:
- Parasitology
- Infectious Diseases
- Public Health
Background:
- Leishmaniases encompass zoonotic infections caused by Leishmania parasites, manifesting in varied clinical presentations influenced by parasite virulence and host immunity.
- Recent outbreaks and novel clinical forms, including viscerotropic leishmaniasis in military veterans, underscore the dynamic nature of these diseases.
- Epidemics of visceral and cutaneous leishmaniasis persist globally, exacerbated by population movements and environmental changes.
Purpose of the Study:
- To review the diverse clinical spectrum and epidemiological patterns of leishmaniases.
- To highlight emerging challenges, including opportunistic infections in HIV/AIDS patients and novel transmission routes.
- To discuss the enzootic transmission cycle of Leishmania mexicana in Texas.
Main Methods:
- Literature review of clinical presentations and epidemiological trends.
- Analysis of emerging transmission dynamics, including parenteral and vector-borne routes.
- Examination of the impact of co-infections, particularly with HIV.
Main Results:
- Leishmaniases exhibit a wide range of clinical manifestations, from cutaneous to visceral forms.
- Increased incidence is linked to population migration into endemic areas and agricultural development.
- Leishmaniasis is a significant opportunistic infection in AIDS patients, with parenteral transmission noted in coinfected individuals.
Conclusions:
- Leishmaniases remain a significant global health threat, with evolving epidemiology and clinical challenges.
- The interplay between HIV and Leishmania presents a critical public health concern, necessitating integrated control strategies.
- Understanding enzootic cycles and novel transmission routes is crucial for effective leishmaniasis prevention and control.