Leishmaniasis Overview Quiz

Leishmaniasis Overview

• Leishmaniasis is a significant vector-borne disease caused by various Leishmania species, mostly zoonotic.
• Different Leishmania species cause diverse disease forms in humans.
• Many species cause skin ulcers and nodules. Some affect mucous membranes, potentially causing disfiguring lesions.
• Other species lead to visceral leishmaniasis, a life-threatening condition damaging internal organs.
• Domestic dogs are a crucial epidemiological factor for the disease.
• Over 90 sandfly species transmit Leishmania parasites.

Learning Objectives

• Understand different types of Leishmaniasis (Cutaneous, Mucocutaneous, Visceral)
• Identify risk factors for Leishmaniasis (Socioeconomic conditions, Malnutrition, Population mobility, Environmental changes).
• Understand Visceral Leishmaniasis (VL) (Causative agent, incubation period, reservoir, mode of transmission, occurrence, prevention and control methods)
• Understand Cutaneous Leishmaniasis (Causative agent, incubation period, reservoir, mode of transmission, occurrence, prevention and control methods)

Leishmania Morphology

• In vertebrate hosts: Amastigotes (Leishman body)
• In sandfly vectors: Promastigotes (Leptomonad)
• Leishmania promastigotes (culture form)

Life Cycle

• Sandfly stages: sandfly takes a blood meal (injects promastigote stage into skin); promastigotes divide and migrate to proboscis
• Human stages: promastigotes are phagocytized by macrophages; transform to amastigotes; amastigotes multiply in various tissues including macrophages

Risk Factors

• Socioeconomic: Poverty correlates with increased risk due to poor housing, sanitation, and access to humans.
• Malnutrition: Protein-energy deficiencies, iron, vitamin A, and zinc deficiencies increase disease progression.
• Population mobility: Migration often accompanies epidemics, exposing non-immune populations.
• Environmental changes: Urbanization and human encroachment into forested areas affect disease incidence.
• Climate change: Changes in temperature, rainfall, and humidity affect vector & reservoir host distributions/survival impacting disease.

Visceral Leishmaniasis (VL)

• Chronic systemic disease caused by intracellular Leishmania protozoa.
• Characterized by fever, hepatosplenomegaly, lymphadenopathy, anemia, leukopenia, thrombocytopenia, progressive emaciation, and weakness.
• Known as Kala-azar.
• Untreated VL is often fatal (over 95% of cases).
• Post-kala-azar dermal leishmaniasis (PKDL) is a possible sequel (rash on face, arms, trunk).
• PKDL usually occurs months to years after initial treatment but can occur sooner.
• People with PKDL are considered potential sources of infection.
• Symptoms include spleen and liver enlargement, night sweats, bouts of temperature, bleeding, skin darkening, scaly skin, cough, weakness, and substantial weight loss.

Cutaneous Leishmaniasis (CL)

• Most common form causing skin lesions (ulcers, scars).
• High incidence in the Americas, Mediterranean basin, Middle East, and Central Asia.
• Over 87% of CL new cases in 2019 were concentrated in 10 countries (Afghanistan, Algeria, Brazil, Colombia, Iran, Iraq, Libya, Pakistan, Syria, and Tunisia.)
• Approximately 600,000 to 1 million new cases worldwide annually.

Mucocutaneous Leishmaniasis

• Leads to partial or total destruction of mucous membranes (nose, mouth, throat).
• Primarily found in Bolivia, Brazil, Ethiopia, and Peru with over 90% of cases concentrated there.

Diagnosis

• VL: Demonstration of intracellular amastigotes in stained smears from bone marrow, spleen, liver, or lymph nodes; PCR is sensitive but costly. Serological diagnosis (IFA and ELISA). Urine antigen detection test. Recombinant k 39 immunochromatographic strip test
• CL: Microscopic identification of amastigotes in stained specimens. Intradermal test (Montenegro) using leishmanin. Serological testing (IFA or ELISA).

Infectious Agents

• Eastern Hemisphere: Leishmania tropica, Leishmania major, Leishmania aethiopica.
• Western Hemisphere: Leishmania braziliensis, Leishmania mexicana.

Reservoirs

• Humans, wild canids (foxes, jackals), and domestic dogs are common reservoirs. Reservoir distribution varies regionally.

Incubation Period

• Generally varies from 2-6 months to even years, ranging from 10 days to years.

Communicability

• Not usually transmitted between people. Infectious to sandflies if parasites are present in blood or skin. Infectivity may persist post-clinical recovery.

Transmission

• Leishmania is transmitted via the bite of infected female phlebotomine sandflies ( P. papatasi and P. sergenti).
• Transmission may rarely occur through blood transfusion.

Susceptibility

• General but Kala-azar induces lasting homologous immunity.

Treatment

• Antimony-containing compounds (meglumine antimoniate, sodium stibogluconate) are frequently used as first-line treatment.
• Amphotericin B or amphotericin B deoxycholate may be used for non-responding cases; liposomal amphotericin B is most effective but expensive.

Control Measures

• Case management: rapid detection and treatment.
• Vector control: applying residual insecticides, especially in breeding locations (rubbish, animal houses) and insecticide-treated bed nets. Eliminate gerbils and other reservoir animals via plowing & removing plants.
• Control of animal reservoirs (dogs, other animals).
• Environmental management: clearing overgrown areas.
• Preventative measures: Although vaccination is in development, no current vaccines exist.

Epidemic Measures

• Case detection and treatment.
• Vector control using indoor residual spray, insecticide-treated bed nets.
• Control of animal reservoirs.
• Surveillance and program monitoring

Leishmania-HIV Coinfection

• HIV increases the chance of developing full-blown leishmaniasis, relapses, and mortality
• Treatment of HIV reduces disease development, delays relapses, and improves survival in co-infected patients.
• Brazil, Ethiopia, and the Bihar region of India have significant rates of this co-infection.

Summary

• Leishmaniasis has 3 forms (visceral, cutaneous, mucocutaneous).
• It is a zoonotic disease mostly transmitted by sandfly bites.
• It disproportionately affects impoverished populations linked to malnutrition, displacement, poor housing, immune weakness, and lack of resources.

This quiz covers the essential aspects of Leishmaniasis, including its various forms and transmission factors. You will learn about cutaneous, mucocutaneous, and visceral leishmaniasis, as well as risk factors and prevention methods. Test your understanding of this significant vector-borne disease caused by Leishmania species.