1. Recurrence patterns and evolution of submicroscopic and asymptomatic Plasmodium vivax infections in malaria-endemic areas of the Peruvian Amazon.
- Author
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Garcia Castillo, Stefano S., Abanto Alvarez, Caroline, Rosas-Aguirre, Ángel, Acosta, Carlos, Corder, Rodrigo M., Gómez, Joaquín, Guzmán, Mitchel, Speybroeck, Niko, Llanos-Cuentas, Alejandro, Castro, Marcia C., Rosanas-Urgell, Anna, Ferreira, Marcelo U., Vinetz, Joseph M., Gamboa, Dionicia, and Torres, Katherine
- Subjects
DISEASE relapse ,PLASMODIUM vivax ,SOCIODEMOGRAPHIC factors ,MALARIA ,FACTOR analysis - Abstract
Background: In the Peruvian Amazon, Plasmodium vivax malaria transmission is maintained due to the high frequency of recurrences. By understanding the recurrence rates of submicroscopic and asymptomatic cases, we can develop informed strategies to prevent transmission more efficiently and disrupt the silent transmission cycle. Methods: A three-year, population-based cohort study was conducted in two sites, Cahuide and Lupuna, within the Loreto region in Peru from 2013 to 2015. The study included 385 individuals and aimed to examine the temporal dynamics of malaria recurrences and their impact on transmission and control. Results: Individuals from Lupuna presented a higher risk of P. vivax infections compared to Cahuide, where most recurrences were asymptomatic and submicroscopic. It is estimated that a great proportion of these recurrences were due to relapses in both communities. The application of molecular diagnostic method proved to be significantly more effective, detecting 2.3 times more episodes during the follow-up (PCR, 1068; microscopy, 467). PCR identified recurrences significantly earlier, at 151 days after an initial infection, compared to microscopy, which detected them on average after 365 days. Community, occupation and previous malaria infections were factors associated with recurrences. Finally, potential infection evolution scenarios were described where one frequent scenario involved the transition from symptomatic to asymptomatic infections with a mean evolution time of 240 days. Conclusions: This study explores the contrast in malaria recurrence risk among individuals from two endemic settings, a consequence of prolonged exposure to the parasite. Through the analysis of the evolution scenarios of P. vivax recurrences, it is possible to have a more complete vision of how the transmission pattern changes over time and is conditioned by different factors. Author summary: The emergence of asymptomatic and lower parasitemia cases has reduced the detection of P. vivax with conventional surveillance methods. This situation raises questions about whether people without symptoms or with low levels of the parasite can still spread the disease and act as sources of infection. In regions with low transmission, like the Peruvian Amazon, our three-year cohort study can help understand how the pattern of transmission changes over time due to various factors. These factors include the time of recurrences detection, factors associated with recurrence development, and evolution and resolution of infections over time. The analysis of the sociodemographic factors has an important contribution to the understanding of the heterogeneous transmission of malaria in the Amazon. By studying malaria endemic communities over an extended period, we have uncovered a high proportion of people experiencing repeated recurrences of the infection, often without showing any symptoms. We have also confirmed that molecular diagnosis methods are more effective. Additionally, our results emphasize the significance of factors such as community, occupation, and previous malaria infection in recurrence cases. Finally, our findings provide valuable insights into the evolution of infections over time and how external factors influence transmission in endemic areas. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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