Investigation strategies and methods
Cultivation of parasites
May 2007
P I D E M I C A L E R T
Laboratory Training for FieldEEpidemiologists
A N D
R E S P O N S E
Learning objectives
At the end of the presentation, participants should:
• Understand the principle of cultivating parasites
• Understand the methods and problems with cultivating parasites
P I D E M I C A L E R T
Laboratory Training for FieldEEpidemiologists
A N D
R E S P O N S E
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
P I D E M I C A L E R T
Laboratory Training for FieldEEpidemiologists
A N D
R E S P O N S E
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
P I D E M I C A L E R T
Laboratory Training for FieldEEpidemiologists
A N D
R E S P O N S E
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
P I D E M I C A L E R T
Laboratory Training for FieldEEpidemiologists
A N D
R E S P O N S E
Other methods of cultivation
Animal inoculation
Xenodiagnosis
• Use of arthropod host as an indicator of infection
• Reduvid bug in the diagnosis of Chagas’ disease
P I D E M I C A L E R T
Laboratory Training for FieldEEpidemiologists
A N D
R E S P O N S E
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
P I D E M I C A L E R T
Laboratory Training for FieldEEpidemiologists
A N D
R E S P O N S E
Investigation strategies and methods
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
P I D E M I C A L E R T
Laboratory Training for FieldEEpidemiologists
A N D
R E S P O N S E