Leishmania braziliensis, Leishmania mexicana- Laboratory diagnosis, Treatment, Prevention, Control

Laboratory diagnosis of Leishmania braziliensis, Leishmania mexicana

The laboratory diagnosis of Leishmania braziliensis, Leishmania mexicana begins with the collection of samples.

Specimen

The lab diagnosis of Leishmania braziliensis Complex and Leishmania mexicana Complex includes:

• skin- biopsy

• ulcer edge aspirates

• nodule aspirates

Microscopy

• stains such as Leishman stain, Giemsa stain, Brown-Hopps stain, or Wright stain can be used for microscopy

• presence of amastigotes confrims the diagnosis

Culture

Leishmania braziliensis and Leishmania mexicana can be cultured in the laboratory both in lab animals and in-vitro culture.

In-vitro culture

• media used includes NNN, Schneider Drosophila medium, or any biphasic medium

• samples are inoculated into the water of condensation or into the fluid of a liquid medium

• incubated at 22° C - 26° C for 1-4 weeks

• at the end of each week, a drop of culture is microscopically examined for promastigotes

• motile promastigotes can be observed in positive cultures

• has a sensitivity of 50% - 75%

• Leishmania mexicana complex grows well in culture while Leishmania braziliensis braziliensis grow poorly or do not grow at all in media cultures

Animal inoculation

• laboratory animals such as Chinese and golden hamsters are inoculated intraperitoneally

• skin biopsy, lesion aspirations are stained and visualized under a microscope

• Leishmania mexicana complex grows fast and produces lesions on the skin while Leishmania braziliensis braziliensis grows slowly and takes time to produce a pathological lesion

Serodiagnosis

The serodiagnosis of Leishmania braziliensis and Leishmania mexicana includes the following methods.

Indirect Immuno-fluorescent (IFA)

• uses fixed amastigotes as antigen

• positive in 89% - 95% of cases

• used to evaluate the response if the patient is treated with chemotherapy as IFA titers fall after successful chemotherapy

Enzyme-Linked Immunosorbent Assay (ELISA)

• uses fixed amastigotes as antigen

• sensitivity of up to 85%

Leishmania skin test (Montenegro test)

Leishmania braziliensis and Leishmania mexicana can also be diagnosed by the Leishmania skin test (Montenegro test).

• delayed hypersensitivity test and is a helpful test

• positive skin test results are also seen in cutaneous and mucocutaneous leishmaniasis

• negative in cases of diffuse cutaneous leishmaniasis

• 0.2 ml of Leishmania antigen is injected intradermally and read after 48-74 hours

• induration and erythema of 5mm diameter or larger are seen in positive cases

Molecular test

Following molecular methods are used for the diagnosis of Leishmania braziliensis, and Leishmania mexicana.

• DNA probes

• PCR

Treatment of Leishmania braziliensis, Leishmania mexicana

Drugs used for the treatment of Leishmania braziliensis, and Leishmania mexicana infection include:

• Pentavalent antimonials

  megalumine antimonate

  sodium stibugluconate solution

• Pentamidine

  pentamidine isethionate

  pentamidine dimethane

• Amphotericin B

• Miltefosine

• Interferon

Prevention, Control of Leishmania braziliensis, Leishmania mexicana

Prevention, Control of Leishmania braziliensis, and Leishmania mexicana can be done by:

• reduction of sand-fly population by using insecticides

• evade contact with potential animal vectors such as dogs, foxes, and rodents

• use of bed nets, window nets, or insect repellents