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Published on: January 3, 2011
Parasite density in severe malaria in Colombia
Julio Cesar Padilla-Rodríguez1, Mario J Olivera2, Bryan David Guevara-García1
1Ministerio de Salud y Protección Social, Bogotá, D.C., Colombia.
Insights
Severe malaria parasite density in Colombia is lower than WHO standards, particularly in low transmission areas. Current parasite density criteria are not suitable for diagnosing severe malaria in Colombia.
Area of Science:
- Medical Entomology
- Infectious Diseases
- Public Health
Background:
- Colombia adopted WHO severe malaria parasite density thresholds (>50,000 parasites/μl).
- These WHO thresholds are based on high-transmission African settings, not Colombia's low and unstable transmission dynamics.
- This discrepancy necessitates evaluating local parasite density levels in severe malaria cases.
Purpose of the Study:
- To determine observed parasite density values in severe malaria patients in Colombia.
- To analyze the distribution of these parasite densities across Colombia's ecoepidemiological regions.
Main Methods:
- Retrospective and descriptive study of confirmed severe malaria cases (2014-2017).
- Data sourced from Subnational Programs of Malaria Prevention and Control.
- Analysis included univariate and bivariate statistics of person, place, and time variables.
Main Results:
- Overall geometric mean parasite density was 5,919 parasites/μl.
- Plasmodium falciparum: 6,151 parasites/μl; Plasmodium vivax: 5,815 parasites/μl.
- Highest densities in the Amazon (8,177 parasites/μl), lowest in the Andean region (5,026 parasites/μl).
Conclusions:
- Severe malaria parasite densities in Colombia are lower than WHO-established values.
- The parasite density criterion is not a relevant or reliable indicator for defining severe malaria in Colombia.
- Clinical decisions regarding malaria severity should not rely solely on parasite density thresholds in this context.
Background:
Colombia has officially adopted the parasite density levels of severe malaria established by the WHO (>50,000 parasites/μl). These values have been inferred from areas of high transmission in Africa and are not consistent with the dynamics of low and unstable transmission in Colombia. The objective of this study was therefore to determine the parasite density values observed in patients with severe malaria and their distribution in the different ecoepidemiological regions of Colombia.
Methods:
A retrospective and descriptive study of confirmed cases of severe malaria was conducted in endemic areas of malaria in Colombia over the period 2014-2017. Data were collected from secondary sources of the Subnational Programs of Malaria Prevention and Control. Person, place, and time variables were selected. The official definition of severe malaria was adopted, and compliance with these criteria was determined. Univariate and bivariate analyses were conducted with absolute and relative frequency measures, and the relevant statistical tests were applied.
Results:
The overall parasite density values in Colombia showed a geometric mean of 5,919 parasites/μl (95% CI: 5,608-6,248). By parasite species, the values were 6,151 (95% CI: 5,631-6,718) for Plasmodium falciparum and 5,815 (95% CI: 5,428-6,230) for Plasmodium vivax. The highest parasite density values were recorded in the Amazon ecoepidemiological region (8,177; 95% CI: 6,015-11,116), and the lowest values were recorded in the Andean region (5,026; 95% CI: 2,409-10,480).
Conclusions:
In endemic areas of low and unstable malaria transmission in the Colombian territory, the parasite density levels observed in populations with severe malaria are lower than the officially established values. The parasite density criterion is not really a relevant criterion for the definition of severe cases in Colombia and it certainly not be used to make a clinical decision about the severity of the disease.
