Rapid Fire Presentation 8th International Conference on Plasmodium vivax Research 2022

Malaria transmission structure in the Peruvian Amazon through antibody signatures to Plasmodium vivax (#317)

Jason Rosado 1 , Gabriel Carrasco-Escobar 2 3 , Oscar Nolasco 3 4 , Katherine Garro 4 , Hugo Rodriguez-Ferruci 5 , Mitchel Guzman-Guzman 4 , Alejandro Llanos-Cuentas 3 , Joseph M. Vinetz 3 6 7 , Narimane Nekkab 1 , Michael T. White 1 , Ivo Mueller 8 , Dionicia Gamboa 4 7
  1. Infectious Disease Epidemiology and Analytics G5 Unit, Institut Pasteur, Paris, Ile de France, France
  2. School of Public Health, University of California San Diego, La Jolla, California, USA
  3. Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
  4. Laboratorio de Malaria, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
  5. Universidad Nacional de la Amazonía Peruana, Iquitos, Loreto, Peru
  6. Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
  7. Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofía , Universidad Peruana Cayetano Heredia, Lima, Peru
  8. Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia

Background:

The landscape of malaria transmission in the Peruvian Amazon is temporally and spatially heterogeneous, presenting different micro-geographies with particular epidemiologies. Most cases are asymptomatic and escape routine malaria surveillance based on light microscopy (LM). Following the implementation of control programs in this region, new approaches to stratify transmission and direct efforts at an individual and community level are needed. We aimed to evaluate the benefits of adding serology to the detection of Plasmodium vivax infections in areas of the Peruvian Amazon where malaria transmission is rapidly reduced.

Methods:

We measured antibody responses against 8 serological exposure markers (SEM) to P. vivax to identify recently exposed people and determine the transmission dynamics of P. vivax in peri-urban (Iquitos) and riverine (Mazán) communities of Loreto, Peru. Socio-demographic, geo-reference, LM and qPCR diagnosis data were collected from two cross-sectional surveys. Spatial and multilevel analyses were implemented to describe the distribution of seropositive cases and the risk factors associated with exposure to P. vivax.

Results:

Low local transmission was detected by qPCR in both Iquitos (5.3%) and Mazán (2.7%); however, seroprevalence indicated a higher level of (past) exposure to P. vivax in Mazán (56.5%) than Iquitos (38.2%). Age and being male were factors associated with high odds of being seropositive in both sites. Higher antibody levels were found in individuals >15 years old. Antibody levels in younger populations (<15 years old) could be a better indicator of recent exposure to P. vivax.

Conclusion:

The large number of current and past infections detected by SEMs allows for detailed local epidemiological analyses, in contrast to data from qPCR prevalence surveys which did not produce statistically significant associations. Serological surveillance will be increasingly important in the Peruvian Amazon as malaria transmission is reduced by continued control and elimination efforts.