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Evaluating measures to control intestinal parasitic infections
D A Bundy1, A Hall, G F Medley
1WHO Collaborating Centre for the Epidemiology of Intestinal Parasitic Infections, Imperial College, London, United Kingdom.
World Health Statistics Quarterly. Rapport Trimestriel De Statistiques Sanitaires Mondiales
|January 1, 1992
Summary
Evaluating intestinal parasitic infections requires different metrics for helminths versus protozoa. Intensity of infection is key for helminths, while prevalence is crucial for protozoa to ensure cost-effective control.
Area of Science:
- Public Health and Epidemiology
- Infectious Diseases
- Parasitology
Background:
- Intestinal parasitic infections are prevalent in developing countries, necessitating cost-effective control measures.
- Evaluating control efficacy requires understanding distinct epidemiological patterns of helminths and protozoa.
Purpose of the Study:
- To highlight the critical differences in evaluating control strategies for intestinal helminths and protozoa.
- To emphasize the importance of selecting appropriate epidemiological parameters for accurate assessment.
Main Methods:
- Analysis of epidemiological patterns for major helminth (e.g., Ascaris lumbricoides, Trichuris trichiura, hookworms) and protozoan (e.g., Entamoeba histolytica, Giardia duodenalis, Cryptosporidium parvum) infections.
- Comparison of the utility of infection intensity versus prevalence as key evaluation parameters for each parasite group.
- Consideration of factors influencing parameter estimation, including age-dependency, spatial clustering, and strain pathogenicity.
Main Results:
- For helminths, infection intensity (mean egg density) is crucial for assessing morbidity and transmission, as prevalence can be misleading.
- For protozoa, prevalence is the primary parameter, though species/strain identification is critical due to the presence of commensals.
- Accurate estimation of intensity for helminths is sensitive to sample size and structure due to overdispersed distributions.
Conclusions:
- Effective evaluation of intestinal parasite control hinges on using infection intensity for helminths and prevalence for protozoa.
- Accurate diagnosis and targeted approaches, especially for pathogenic protozoan strains, are vital for cost-effective interventions.
- Understanding parasite-specific epidemiological patterns is essential for successful public health strategies in endemic regions.