Figure 2.
Age-specific relative frequency of patent vs. sub-patent and symptomatic vs. asymptomatic Plasmodium vivax infections diagnosed by polymerase chain reaction across six studies in the Amazon. Patent (red symbols) and sub-patent (blue symbols) infections are shown in A; symptomatic (red symbols) and asymptomatic (blue symbols) P vivax infections are shown in B. Error bars indicate 95% confidence intervals of proportions We pooled data from cross-sectional surveys carried out in six sites. CAH: villages of Cahuide, La Habana, and Doce de Abril, all in Loreto, Peru.11,14 LUP: villages of Lupuna, Santa Rita, and San Pedro, all in Loreto, Peru.11,14 ACR: 7 farming settlements in Acrelândia, Acre, Brazil.12 GRA: Granada farming settlement, Acre, Brazil.17 JAU: 14 riverine villages in Jaú National Park, Amazonas, Brazil.8 REM: Remansinho farming settlement, Amazonas.10 The number of observations in each age group was as follows: CAH, 0–5 years, 1,421; 6–15 years, 3,017; 16–40 years, 3,082; 41 years and older, 2,261; total, 9,781. LUP, 0-5 years, 986; 6–15 years, 2,006; 16–40 years, 3,021; 41 years and older, 2,443; total, 8,456. ACR, 0–5 years, 261; 6–15 years, 715; 16–40 years, 856; 41 years and older, 737; total, 2,569. GRA, 6–15 years, 427; 16–40 years, 627; 41 years and older, 304; total, 1,358. (Under-five children from GRA were removed, as this age group has not been systematically sampled during the community-wide surveys.) JAU, 0–5 years, 238; 6–15 years, 280; 16–40 years, 373; 41 years and older, 152; total, 1,043. REM, 0–5 years, 205; 6–15 years, 454; 16–40 years, 605; 41 years and older, 515; total, 1,779. The symptom-free period used to define asymptomatic parasite carriage was at least 7 days before sample collection in CAH, LUP, ACR and REM, at least 30 days before and 30 days after blood collection in GRA, and at least 30 days before and 15 days after blood collection in JAU. Error bars indicate 95% confidence intervals of proportions.