On March 2nd 2017, Dr. Peter Veldkamp hosted a meeting of the Infectious Disease ‘Bug Club’. A number of medical students, fellows and Infectious Disease faculty attended the meeting. The discussion revolved around the protozoan parasite Leishmania, and Alex Linn and Akshaya Arjunan, two 2nd year medical students at the University of Pittsburgh Medical School, discussed their research involving methods to more rapidly and accurately diagnose this pathogen in order to streamline care and improve clinical outcomes, particularly in resource-limited settings where this parasite is endemic.
Akshaya’s research involved obtaining the sensitivity and specificity of diagnosing visceral leishmaniasis through analysis of the leukoconcentration layer of peripheral blood. This was done by sampling 5-10 mL of peripheral blood from infected patients and looking for amastigotes in Giemsa stained blood smears. Currently, the gold standards for diagnosing this disease in patients are PCR and bone marrow aspirations. However, PCRs are costly and bone marrow aspirations are invasive, thus her project aim was to see if this noninvasive method could potentially replace the invasive diagnostic techniques currently available. In addition, she worked with another post-doc in order to jumpstart a project involving xenodiagnosis. In this study, laboratory-bred sandflies were used to feed on infected patients for about 30-45 minutes, in the hopes of obtaining circulating amastigotes. Once the sandflies were allowed to mature for about 10 days, they were dissected to see if promastigotes could be visualized in the sandfly gut. This project was another method in attempting to uncover noninvasive diagnostic methods and potentially open the door for artificial xenodiagnostic methods.
Alex’s research aimed to identify if a centrifuged traditional culture method was a more sensitive and rapid method of diagnosing Visceral leishmaniasis (VL) than the traditional culture method currently employed. In Brazil, traditional culture is the gold standard for diagnosing VL, but requires a long incubation period (7-30 days) which often postpones initiation of treatment. Alex conducted a pilot study where she enrolled 16 participants between 3-66 years with clinical suspicion of VL, and created traditional and centrifuged cultures of their bone marrow. The results showed that the centrifuged culture methods had better sensitivity and produced positive results faster than the traditional culture method, with identified parasites in 2-5 days compared to 5-14 days. Her research is being continued by Brazilian students to further investigate this potential diagnostic method.
Both Alex and Akshaya were mentored by Drs. Fernanda Silveira and Peter Veldkamp from the Division of Infectious Disease.
During their discussion, samples of various species of sandflies known to harbor the parasite were passed around for observation:
The meeting concluded with a talk from a Veterinarian that the students had interacted with during their time in Brazil, who interestingly was working on a vaccine against Leishmania for dogs, which are known to carry the parasite and promote its transmission into humans.
Some key points regarding Leishmaniasis were reviewed during the meeting as well:
- It is caused by the protozoan parasite of the genus Leishmania
- Spread of infection occurs via Sandflies
- There are 3 primary forms of the disease: cutaneous, mucocutaneous, and visceral (known also as Kala-Azar); each type is caused by different species of Leishmania, and each is endemic to a different area of the world
- Cutaneous disease involves the skin, while mucocutaneous disease involves the mucous membranes of the nose and mouth
- Visceral leishmaniasis is often associated with pancytopenia, fevers, and hepato-splenomegaly
- Diagnosis is achieved primarily through DNA testing or culturing of bone marrow or skin lesions
- Treatments include sodium stibogluconate, amphotericin B, and miltesfosine, which was most recently approved for mucocutaneous disease
A link to the slides from the presentation is here: Leishmaniasis PDF