The development of clinical immunity toPlasmodium falciparummalaria is thought to require years of parasite exposure, a delay often attributed to difficulties in developing protective antibody levels. In this study, we evaluated severalP. falciparumvaccine candidate antigens, including apical membrane antigen 1 (AMA-1), circumsporozoite protein (CSP), erythrocyte binding antigen 175 (EBA-175), and the 19-kDa region of merozoite surface protein 1 (MSP1₁₉). After observing a more robust antibody response to MSP1₁₉, we evaluated the magnitude and longevity of IgG responses specific to this antigen in Peruvian adults and children before, during, and afterP. falciparuminfection. In this low-transmission region, even one reported prior infection was sufficient to produce a positive anti-MSP1₁₉IgG response for >5 months in the absence of reinfection. We also observed an expansion of the total plasmablast (CD19⁺CD27⁺CD38^high) population in the majority of individuals shortly after infection and detected MSP1-specific memory B cells in a subset of individuals at various postinfection time points. This evidence supports our hypothesis that effective antimalaria humoral immunity can develop in low-transmission regions.

The pandemic generated by SARS‐Cov‐2 has caused a large number of cases and deaths in the world, but South America has been one of the continents that were most hard hit. The appearance of new variants causes concern because of the possibility that they may evade the protection generated by vaccination campaigns, their greater capacity to be transmitted, or their higher virulence. We analyzed the circulating variants in Peru after improving our Genomic Surveillance program. The results indicate a steep increase of the lambda lineage (C.37) until becoming predominant between January and April 2021, despite the cocirculation of other variants of concern or interest. Lambda lineage deserves close monitoring and could probably become a variant of concern in the near future.

Emergencia del genotipo Cosmopolitan del virus dengue serotipo 2 (DENV2) en Madre de Dios, Perú, 2019

Objectives. This study aimed to evaluate the prevalence and distribution of dengue virus genotype V serotype 1 (DENV-1) and cosmopolitan genotype serotype 2 (DENV-2) in Peru between 2019 and 2022. Materials and methods. The envelope (E) gene region was amplified from 79 serum samples by polymerase chain reaction (PCR) and sequenced by next-generation sequencing (NGS) technology. The obtained sequences were subsequently analyzed with bioinformatics tools. Results. The study generated envelope gene sequences of DENV-1 and DENV-2 serotypes. Our study revealed a rapid dispersal and wide distribution of the cosmopolitan DENV-2 genotype in several regions of Peru in 2022, as well as the spread of DENV-1 genotype V to new Peruvian regions, along with the cosmopolitan DENV-2 genotype. Conclusions. Our findings suggest the urgent need to strengthen epidemiological and genomic surveillance systems to understand and control the spread of circulating DENV genotypes in Peru. This will allow a more rapid response, as well as the monitoring of its potential dissemination to other countries in the Americas.

As has occurred in many regions worldwide, in 2012 the incidence of pertussis increased in Perú. This epidemiologic situation has been associated with a waning vaccine-induced immunity and the adaptation of Bordetella pertussis to vaccine-induced immunity along with improved diagnostic methods. The study comprised a total of 840 pertussis-suspected cases reported in Perú during 2012. We summarize here the distribution of pertussis cases according to age and immunization status along with the immunization-coverage rate. Laboratory diagnosis was performed by culture test and real-time polymerase-chain reaction (PCR). B. pertussis bacteria recovered from infected patients were characterized by pulsed-field gel electrophoresis (PFGE), and the DNA sequencing of the pertussis-toxin (promoter and subunit A), pertactin, and fimbriae (fim2 and fim3) genes. From the total pertussis-suspected cases, 191 (22.7 %) infections were confirmed by real-time PCR and 18 through cultivation of B. pertussis (2.1 %), while one infection of B. parapertussis (0.11 %) was also detected by culture. Pertussis was significantly higher in patients that had had 0–3 vaccine doses (pentavalent vaccine alone) than in those who had had 4–5 vaccine doses (pentavalent plus DwPT boosters) at 94.3 vs. 5.7 %, respectively (p < 0.00001). The relative risk (RR) for patients with 4–5 doses compared to those with fewer than 4 doses or no dose was 0.23 (95 % Confidence Interval: 0.11–0.44), while the vaccine effectiveness was 77 % and coverage 50.5 %. Genetic analysis of B. pertussis isolates from different Peruvian regions detected two clonal groups as identified by PFGE. Those two groups corresponded to the B. pertussis genotypes emerging worldwide ptxP3-ptxA1-prn2 or 9-fim3-1 and ptxP3-ptxA1-prn2 or 9-fim3-2. Two emerging B. pertussis genotypes similar to isolates involved in worldwide epidemics were detected in Perú. Low vaccine coverage (<50 %) and genetic divergence between the vaccine-producing strain and the local isolates could contribute to this pertussal epidemic.