Laboratory Training for Field Epidemiologists Cultivation of parasites Investigation strategies and methods May 2007

Laboratory Training for Field Epidemiologists Learning objectives At the end of the presentation, participants should: Understand the principle of cultivating parasites Understand the methods and problems with cultivating parasites

Laboratory Training for Field Epidemiologists Common parasite diagnostics Detection of parasites in clinical specimen by Morphologic criteria rather than culture Biochemical tests Physical growth characteristics Final identification Based upon microscopic examination of unstained/stained preparations Provides information up to species level in most cases

Laboratory Training for Field Epidemiologists Methods of cultivation Offered by very few laboratories Complex methods, difficult quality control Ordered only after consultation with laboratory Few parasites can be cultured: E histolytica, N fowleri, Acanthomoeba spp., T vaginalis, T gondii, T cruzi, Leishmani spp., Plasmodium spp., certain life forms of more complex parasites

Laboratory Training for Field Epidemiologists In vitro cultivation Xenic cultures Culture of parasites grown in association with an unknown microbiota (i.e. microbial population) Cultivation of E histolytica Monoxenic cultures Parasite grown in association with a single known bacterium Acanthomoeba culture from corneal biopsy with E coli Axenic cultures Pure culture without bacterial associate Leishmania culture

Laboratory Training for Field Epidemiologists Other methods of cultivation Animal inoculation Xenodiagnosis Use of arthropod host as an indicator of infection Reduvid bug in the diagnosis of Chagas’ disease

Laboratory Training for Field Epidemiologists When do we culture parasites? Obtain definitive identification Repeated microscopy fails, indirect evidence (e.g., antibody response) not conclusive Test antimicrobial susceptibility Measure response to treatment Characterize the agent Strain bank for future use Vaccine development, antigen production, research Rapid antigen detection tests are increasingly becoming useful

Laboratory Training for Field Epidemiologists Developed by the Department of Epidemic and Pandemic Alert and Response of the World Health Organization with assistance from: European Program for Intervention Epidemiology Training Canadian Field Epidemiology Program Thailand Ministry of Health Institut Pasteur Investigation strategies and methods