Diagnosis of Visceral Leishmaniasis may
require taking a blood sample and/or taking a biopsy from the bone
marrow or splenic puncture to show the parasite.
Diagnosis of Cutaneous Leishmaniasis
will require a small biopsy or scrapping of ulcer.
Diagnosis of Mucocutaneous
Leishmaniasis requires a biopsy of the affected tissues.
Biopsy samples are examined by
microscopy, culture and other methods to look for the parasite and
identify the specific kind of leishmania causing the ulcer.
Sample for Visceral Leishmaniasis
- Blood:Blood film/Blood Culture and Serological Tests.
- Bone Marrow: Biopsy material obtained by sternal or iliac crest puncture.
- Splenic Pulp: Biopsy material obtained by splenic culture.
As the clinical presentation of
Visceral Leishmanisis (Kala azar) lacks specificity, confirmatory
tests are required to decide which patients should be treated. Such
tests should be highly sensitive (>95%) as VL is a fatal
condition, but also highly specific because the current drugs used to
treat VL are toxic. Ideally, a test should be able to make the
distinction between acute disease and asymptomatic infection, because
none of the drugs currently available is safe enough to treat
asymptomatic infections. Moreover, such tests should be simple and
affordable.
Non Leishmanial Test:
a. Detection of reduction in the
number of red and white blood cells and platelets (pancytopenia) in
VL suspected clinicla patients. This test is highly specific but
sensitivity is very low.
b. Aldedhyde Test (also called Formal
Gel Test: FGT): Polyclonal hypergammaglobulinemia (the production of
high titres of non-specific antibody) is detected in this test.
Sensitivity of this test is poor, as low as 34%.
In this test 1-2 drops of serum from a case of kalaazar is taken and a drop or two of formalin is added. A positive test is indicated by jellification to milk white opacity like the white of a hard boiled egg so that in ordinary light, newsprint is invisible through it.
In this test 1-2 drops of serum from a case of kalaazar is taken and a drop or two of formalin is added. A positive test is indicated by jellification to milk white opacity like the white of a hard boiled egg so that in ordinary light, newsprint is invisible through it.
Leishmanin Test:
A killed culture (0.1-0.2 ml) of a
suspension containing 6 to 10 promastigotes per ml is injected
intradermally. A positive reaction (an area of induration after 72
hours) is produced in cured kala azar cases 6 to 8 weeks after
recovery and represent a delayed hypersensitivity reaction
accompanied by cell-mediated immunity. The test is positive in
African Kala azar but not in indian and mediterranean kala-azar and
post kala azar dermal leishmaniasis.
Parasite detection
For the detection of parasite
visualization of the amastigote form of the parasite by microscopic
examination of aspirates from lymph nodes, bone marrow, or spleen is
done. It is the classic confirmatory test for Visceral Leishmaniasis.
Although the specificity is high, the sensitivity of microscopy varies, being higher for spleen (93% to 99%) than for bone marrow (53-86%) or lymph nodes aspirates (53-65%) .
Although the specificity is high, the sensitivity of microscopy varies, being higher for spleen (93% to 99%) than for bone marrow (53-86%) or lymph nodes aspirates (53-65%) .
The detection of parasites in the blood
or organs by culture or by using molecular techniques such as PCR is
more sensitive than microscopic examination.
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