Protozoa 2b): Cutaneous Leishmaniasis Flashcards
Which species of leishmania cause cutaneous lesions and where does CL most commonly occur?
90% occur in Afghanistan, Algeria, Brazil, pakistan, peru, Saudi Arabia and Syria
1.5M cases reported annually
90% of muco-cutaneous leishmania occur in Bolivia, Brazil, peru.
L. tropica, L. major and L. aethiopica are important causes of Old World CL whereas New World disease is caused by leishmania which are named after a local country or area, e.g. L. mexicana, L. peruviana, L. amazonis, L. viannia (L. Braziliensis) Common ‘Old World’ hosts for CL include dogs, rodents, foxes, jackals and wolves. Common New World hosts include rodents, sloths, anteaters, and monkeys. Old World CL is found in the Middle East, the Indian subcontinent, Asia, the Mediterranean, East Africa, and in the Republics of the former Soviet Union. Large numbers of travellers and military personnel returning from these areas are nowadays presenting with CL (Oriental sore, Aleppo sore, Baghdad boil).
What are the different types of cutaneous leishmania?
- Cutaneous Leishmanisis
- Mucocutaneous Leishmaniasis
- Diffuse Cutaneous Leishmaniasis
- Leishmania Recidivans
How does CL present clinically?
Papule → nodule → ulcer [typically raised edge/crater], usually painless
- Either a single lesion or other satellite cutaneous lesions
- Mucuocutaneous Leishmaniasis can be an early or late complication of some cutaneous infections in the New World species. The parasites disseminate to the naso-oralpharyngeal mucosa where they destroy the mucosa.
- Diffuse Cutaneous Leishmaniasis is a rare complication usually of L Mexicana + Aethiopica – failure of immunity leads to diffuse parasites resulting in a nodular appearance [it can look lepromatous]. Poor response to treatment.
- Leishmania Recividans is a rare form of disease seen in Syria/Iran/Iraq. Typically causes recurrent facial lesions and can persist for decades.
The Koebner phenomenon (isomorphic reaction) occurs when new lesions appear on healthy skin which has suffered a trauma. It is found also in psoriasis, molluscum contagiosum, warts, and vitiligo and in lichen planus.
Leishmania species are morphologically identical and are differentiated on the basis of their isoenzymes and nucleic acid composition. The skin lesions of CL are usually painless.
How do the lesions by the different CL protozoa differ?
Picture mucocutaneous leishmaniasis
Espundia is mucocutaneous leishmaniasis (ML). It is a dreaded disfiguring mucocutaneous complication of New World CL usually due to L. viannia (L. braziliensis). It may occur while the primary lesion is still present or appear years after the initial CL has healed. The oropharyngeal mucosa is attacked by amastigotes, which gradually erode the nasal cartilage resulting in gross deformity.
ML causes multiple painful ulcers affecting the larynx and oral mucosa and is due L. infantum. Approximately 90% of all cases of ML occur in Bolivia, Brazil and Peru with the remaining 10% occurring in the Old World, chiefly in southern Europe, the Middle East and central Asia.
Picture diffuse leishmaniasis
Treatment for CL?
Treatment is complex and depends on the clinical type and infecting organism
Local therapy • Some cases of cutaneous leishmaniasis might be candidates for local therapy, such as cryotherapy (with liquid nitrogen), thermotherapy, intralesional administration of SbV and topical paromomycin
Some lesions do not need treatment at all. Others can use:
Pentavalent antimonial therapy (Pentostam); Miltefosine
Amphotericin B
Pentamidine
What is the Leishmanin skin test?
Normally a positive Leishmanin test is maximal at 48 h. However diagnosis is better made by clinical observation and better still by culture of amastigotes or by use of PCR and isoenzyme studies.
In endemic areas a positive test using cultured promastigotes is found in a high proportion of the population as well as in those with established disease. This limits the usefulness of the Leishmanin test. It is further limited by the fact that the test is negative during an acute leishmanial infection.
The Leishmanin test uses a killed promastigote suspension as antigen (area and species specific). It is read after 48h.It is usually positive in established CL and ML.
What other disease to sandflies transmit?
Sandflies are mainly known for transmitting leishmania. But they can also transmit viral sandfly fever and bartonellosis. Sandfly fever is due to a virus and is generally a self-limiting 3-day illness.
Bartonellosis (Bartonella bacilliformis) is transmitted by lutzomyia sandflies and is found only in hilly areas of Peru, Ecuador and Colombia. Bartonellosis is also called Oroya Fever or Carrion’s disease. Daniel Carrion was an heroic Peruvian medical student who died from self-inflicted bartonellosis while investigating the disease in 1885.
Sandflies do not bite through clothing because of their small mouthparts. They are crepuscular and darkness feeders and seldom disperse more than 100 m.
What are the differences between diffuse CL and disseminated CL?
