The Laroche Lab studies the epidemiology, transmission and pathogenesis of bacteria infecting the endothelium. The current main projects are listed below:

• Investigate the ecology of Rickettsia rickettsii in the U.S. and Latin America. Rocky Mountain spotted fever is a life-threatening, yet neglected, bacterial vector-borne disease transmitted by ticks in the Americas. The fatality rates are significantly higher in Latin America. We use tick/animal transmission models, virulence studies etc. to explore the bases of this observation and explain whether these disparities in mortality rates are due to the tick vectors, the rickettsial clades or other factors.
• Acute febrile illnesses in displaced populations. Refugee camps are a favorable environment for the emergence, maintenance and spread of human pathogens. We determine the burden of vector-borne bacterial diseases among other etiologies of acute undifferentiated fevers in refugee populations from East-Africa and migrant populations from South America. Isolates from febrile patients, arthropods and animals are fully characterized and transmission models are performed in order to confirm vector transmission. Rickettsia and Bartonella spp. isolates are further used for pathogenesis studies.
• Pathogenesis of Bartonella species. Bartonella species are vector-borne bacteria commonly associated with domestic animals and small wild rodents and transmitted by fleas and lice. They are highly sensitive to antibiotics and rarely cause severe infections in immunocompetent patients. In immunocompromised patients, they can cause a wide range of clinical manifestations that include endocarditis, bacillary angiomatosis, bacillary peliosis, encephalopathy, neuroretinitis etc. We study the pathogenesis of Bartonella species in the endothelium using in vitro and in vivo models of severe bartonellosis.