Covers the genus Leishmania, the protozoan parasites behind leishmaniasis, starting with its taxonomy and sand fly transmission. It describes the amastigote and promastigote forms, the animal and human hosts, and the transmission cycle, then the cutaneous, mucocutaneous and visceral clinical forms. Diagnosis by microscopy, culture, serology and PCR, and prevention measures close the note. A recap question set and four mnemonics for forms, clinical types, sand fly genera and visceral symptoms are included.
Topic 80 of 105 in the MU Sofia syllabus for Biology (Medicine, Year 1). The free AceMed note covers it in 9 sections, about 1,323 words (9 min of reading), with 18 flashcards.
In this note
Genus Leishmania
Introduction to Leishmania
Morphological Forms of Leishmania
Host Range and Reservoirs
Vector and Transmission
Life Cycle in Detail
Clinical Forms of Leishmaniasis
Diagnosis Methods
Prevention and Control Measures
Introduction to Leishmania
Leishmania is a genus of protozoan parasites that cause a group of diseases collectively known as leishmaniasis.
These parasites are obligate intracellular organisms, meaning they must live inside host cells to survive and reproduce.
The genus belongs to the family Trypanosomatidae and order Kinetoplastida, characterized by the presence of a kinetoplast, a unique DNA-containing structure inside their single large mitochondrion.
They are transmitted by the bite of infected female sand flies and affect both humans and a variety of animal hosts.
Morphological Forms of Leishmania
A. Amastigote Form
Location: Found within the cells of the vertebrate host, particularly macrophages and dendritic cells.
Structure:
Small, oval to round-shaped form.
Lacks an external flagellum, making it non-motile.
Has a nucleus and a kinetoplast, but the flagellum is internal and not visible.
Function:
This is the replicative form inside the host.
Amastigotes multiply by binary fission inside the host's phagocytic cells.
When infected cells rupture, they release more amastigotes that infect nearby cells.
Transformation:
Promastigotes injected by the sand fly transform into amastigotes after being engulfed by host immune cells.
B. Promastigote Form
Location: Found in the gut of the sand fly vector.
Structure:
Slender, elongated, spindle-shaped.
Possesses a single anterior flagellum for motility.
Contains both a nucleus and a kinetoplast near the base of the flagellum.
Function:
This is the infective form for the vertebrate host.
Promastigotes are actively motile and attach to the sand fly gut lining.
They transform into amastigotes once injected into the host and taken up by phagocytic cells.
Continue reading free
The whole note, all 9 sections, is free with an AceMed account, with its 18 flashcards. Premium adds flashcard recall, highlights and Ask AI.
