Leishmania Species and Transmission

Leishmania Species

• Leishmania species are parasites affecting human blood and tissues.
• They cause leishmaniasis.
• Leishmania species belong to the Protozoa group, specifically Flagellates.

Key Groups of Parasites

• Parasites affecting humans include Metazoan parasites (Helminths) and Protozoan parasites (Protozoa).

Leishmania Development

• Leishmania exists in two developmental stages: amastigote (develops inside the patient's body) and promastigote (develops outside the patient's body).
• Species differentiation can be determined through isoenzyme analysis, molecular methods, or monoclonal antibodies.
• All Leishmania species are spread to humans through an infective female sand fly bite.

Sand Fly Transmission

• Sand flies (Phlebotomus papatasii) transmit Leishmania infection by extracting amastigotes from a patient's skin, transforming them to promastigotes within the sand fly, and then injecting the promastigotes into the bite wound of a healthy person.

Leishmaniasis Types

• Cutaneous leishmaniasis: Infection affecting human skin, characterized by an ulcer with a sharply demarcated, hard, and rough margin. The ulcer typically takes about a year to heal, leaving a disfiguring scar.

  • The parasite multiplies within skin macrophages, eliciting a characteristic granuloma formation.
  • Leishmania tropica, major, and aethiopica are common species associated with skin ulcers.

• Visceral leishmaniasis (Kala-azar): Infection affecting human internal organs (viscera—e.g., liver, spleen, bone marrow).

  • Caused by the Leishmania species infantum, chagasi, and donovani.
  • Characterized by: high fever, intermittent, double daily rise (spiking fever), spontaneous bleeding from the gums, massive splenomegaly and hepatomegaly, lymphadenopathy, weight loss, possible death from intercurrent infections (e.g., pulmonary and gastrointestinal).

Geographic Distribution of Leishmania Infections

• Leishmania infections occur globally.
• Specific locations experience different types of Leishmania infections.
  • Middle East and Africa: Leishmania tropica (dry ulcer), Leishmania major (wet ulcer), and Leishmania aethiopica (nodular lesions that don't ulcerate)
  • South America: Leishmania species that cause dry ulcer, diffuse lesion, and mucocutaneous leishmaniasis.
• Central America: Leishmania species with ulcers that cause cartilage damage.

Leishmaniasis Diagnosis

• Cutaneous: Detect amastigotes microscopically at the ulcer edge. Samples are collected via aspiration, scraping, or biopsy. Culturing on a suitable medium to identify promastigotes is also possible.
• Visceral: The initial step is a complete blood count (CBC) with reduced red blood cell, white blood cell, and platelet counts to detect infection. Confirmation occurs with Bone marrow aspiration/biopsy, or biopsies from other affected viscera. Culture of materials harvested from the affected viscera is also used.
• Molecular Techniques: DNA detection through PCR is used for diagnosis, showing rapid results.
• Serological Tests: Detecting anti-Leishmania antibodies.

Treatment

• Cutaneous Leishmaniasis: Treatment includes sodium stibogluconate (intra-muscularly) or liposomal amphotericin B. Ulcer treatment includes different methods of injection or topical applications (e.g., heating/freezing or surgery).
• Visceral Leishmaniasis: Treatment also often includes sodium stibogluconate or liposomal amphotericin B.

Prevention & Control

• The ministry of health is tasked with treating patients, controlling sand fly vectors, and vaccinating people in endemic areas.
• Individuals should use protective measures like wire screens, repellents, and bed nets.

Additional Information

• The protozoa's location in the patient's body is in the reticuloendothelial cells.

This quiz covers essential knowledge about Leishmania species, their developmental stages, and the transmission method through sand flies. Learn about the life cycle of these protozoan parasites and their impact on human health. Test your understanding of leishmaniasis and its causative agents.