Shaden Kamhawi, Ph.D.

The research program is focused on basic and translational aspects of leishmaniasis, a neglected vector-borne disease (NTD) transmitted by phlebotomine sand flies.

For basic research, the team uses Leishmania-infected sand flies as a natural transmission model for the study of leishmaniasis. Findings from the work emphasized the critical contribution of vectors in the initiation and establishment of vector-borne disease. Recently, the group demonstrated that vector-derived factors lead to acute inflammation found to be key to Leishmania parasite establishment and dissemination. The group also showed that bleeding at the site of bites, that is prolonged due to the anti-hemostatic effects of saliva, triggers the cell stress response and heme oxygenase-1 induction, which dampens inflammation. These bite-specific immune events shape the early response to Leishmania parasites and govern disease outcome. The group continues to investigate the host immune response to vector bites, using it in combination to known risk factors for disease development. Currently, in collaboration with Dr. Peter Melby, University of Texas Medical Department at Galveston, the group is investigating the effect of malnutrition on the course of sand fly transmitted visceral leishmaniasis.

For preclinical research, the team is involved in investigating the efficacy of promising vaccines against leishmaniasis using infected sand flies as challenge. We are currently validating a live attenuated vaccine developed by Hira Nakhasi (US Food and Drug Administration), Abhay Satoskar (Ohio State University) and Greg Matlashewski (McGill University), and working towards developing a human challenge model of cutaneous leishmaniasis.

For translational research, Dr. Kamhawi has a keen interest in field-oriented studies based in leishmaniasis foci. The group has made fundamental discoveries of factors controlling vector competence under laboratory conditions that have yet to be demonstrated in field settings. Currently, Dr. Kamhawi is collaborating with multiple international partners in the Indian subcontinent, East Africa, West Africa and Brazil looking at drivers of transmission in cutaneous and visceral leishmaniasis foci and assessing the relevance of sand fly gut microbiota and longevity in disease prevalence and pathogenicity. The group is also developing markers of exposure to specific vectors and will assess their efficacy as a surveillance tool to be used in monitoring human-vector contact in endemic populations during interventions. Main collaborators are Caryn Bern (UCSF), Sridhar Srikantiah (Care India), Abhay Satoskar (OSU), Seydou Doumbia (University of Bamako), Damaris Matoke (KEMRI), Asrat Hailu, (Addis Ababa University), Ahmed Musa (University of Khartoum) and Claudia Brodskyn (FIOCRUZ).

Dr. Kamhawi is a strong advocate for promoting science in NTD countries and has been serving the community as co-editor-in-chief for PLOS Neglected Tropical Diseases since 2019.

A tridimensional view of a macrophage (IBA-1, yellow; DAPI, blue) from mouse skin expressing heme oxygenase-1 (HO-1, red) after ingesting a red blood cell (TER-119, white) 18 hours after sand fly bites.

Credit: NIAID