Parasite density in 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.