In the early 2015, several cases of patients presenting symptoms of mild fever, rash, conjunctivitis and arthralgia were reported in the northeastern Brazil. Although all patients lived in a dengue endemic area, molecular and serological diagnosis for dengue resulted negative. Chikungunya virus infection was also discarded. Subsequently, Zika virus (ZIKV) was detected by reverse transcription-polymerase chain reaction from the sera of eight patients and the result was confirmed by DNA sequencing. Phylogenetic analysis suggests that the ZIKV identified belongs to the Asian clade. This is the first report of ZIKV infection in Brazil.

A panel of national experts was convened by the Brazilian Infectious Diseases Society in order to organize the national recommendations for the management of zika virus infection. The focus of this document is the diagnosis, both clinical and laboratorial, and appropriate treatment of the diverse manifestations of this infection, ranging from acute mild disease to Guillain-Barré syndrome and also microcephaly and congenital malformations.

In immunocompromised patients, visceral leishmaniasis (VL) can present with atypical clinical symptoms that include poor response to treatment. No optimal therapeutic regimen is available for such cases. In a splenectomized male patient, we observed a disseminated form of the disease in the liver, bone marrow, lymph nodes, and gastrointestinal tract. There was an apparent clinical improvement when he was initially treated with liposomal amphotericin B (L-AmB), but this was followed by a relapse involving severe clinical symptoms. He was finally treated successfully with a combination of L-AmB, meglumine antimoniate, and pentamidine isethionate. It is important to include asplenia as an immunosuppressive condition that induces exotic VL pathologies. In such cases, combination anti-Leishmania drug therapy should be considered.

A phase III dengue vaccine trial including 9- to 16-year-olds in Latin America (NCT01374516) was ongoing at the time of a Zika outbreak. We explored interactions between dengue and Zika, in the context of dengue vaccination. Symptomatic virologically confirmed Zika (VCZ) was evaluated using acute-phase sera from febrile participants (January 2013–March 2018). Neutralizing antibody geometric mean titers (GMTs) were evaluated pre- and post-Zika outbreak (months 25 and 72) in 2,000 randomly selected participants. Baseline dengue serostatus was determined using the plaque reduction neutralization test or inferred post hoc using nonstructural protein 1 IgG ELISA at M13 (case–cohort analysis). Vaccine efficacy against VCZ and serologically suspected Zika (SSZ) was estimated. Overall, 239/10,157 (2.4%) acute-phase samples were VCZ positive during the study. Dengue vaccine efficacy against VCZ was 27.8% (95% CI: 0.3; 47.7) among baseline dengue-seropositive participants. No vaccine effect was evident against SSZ. Zika antibody GMTs increased from pre- to post-Zika epidemic, with smaller increases observed for participants who were dengue seropositive at baseline than for those who were dengue seronegative: post-/pre-Zika GMT ratios for baseline dengue-seropositive participants were 21.5 (vaccine group) and 30.8 (placebo); and for dengue seronegatives, 88.1 and 89.5, respectively. Dengue antibody GMTs post-Zika were higher in dengue vaccine and placebo recipients with SSZ than those without SSZ in both dengue seropositives and seronegatives. Dengue vaccine did not enhance symptomatic Zika illness in dengue-seropositive individuals, rather it reduced the risk of VCZ. Zika infection boosted preexisting vaccine-induced or naturally occurring dengue-neutralizing antibodies.

The emergence and continued geographic expansion of arboviruses and the growing number of infected people have highlighted the need to develop and improve multiplex methods for rapid and specific detection of pathogens. Sequencing technologies are promising tools that can help in the laboratory diagnosis of conditions that share common symptoms, such as pathologies caused by emerging arboviruses. In this study, we integrated nanopore sequencing and the advantages of reverse transcription polymerase chain reaction (RT-PCR) to develop a multiplex RT-PCR protocol for the detection of Chikungunya virus (CHIKV) and several orthoflaviviruses (such as dengue (Orthoflavivirus dengue), Zika (Orthoflavivirus zikaense), yellow fever (Orthoflavivirus flavi), and West Nile (Orthoflavivirus nilense) viruses) in a single reaction, which provides data for sequence-based differentiation of arbovirus lineages.

Yellow fever remains a major public health threat in endemic and re-emerging regions of Africa and South America, with recent outbreaks highlighting persistent gaps in prevention and surveillance. Pregnant women represent a particularly vulnerable population, yet the epidemiology, clinical impact, and preventive strategies for yellow fever in pregnancy are insufficiently characterized. Physiological and immunological changes during gestation may influence host responses to infection; however, current evidence does not demonstrate increased susceptibility to or severity of yellow fever during pregnancy. Adverse materno-fetal outcomes, including miscarriage, stillbirth, preterm birth, and, in rare cases, perinatal transmission, have been reported but remain poorly characterized. Diagnostic challenges, overlapping clinical presentations with other arboviral and hepatic diseases, and limited access to specialized care further complicate clinical management in many endemic settings. This perspective provides a comprehensive overview of yellow fever in pregnancy during the 2024–2026 outbreak in the Americas, including a risk-stratification framework for prevention. We summarize current evidence on epidemiology, pathophysiology, diagnosis, and supportive care, and examine prevention strategies with particular emphasis on vaccination. Accumulated observational evidence and substantial real-world experience have not demonstrated an increased risk of serious adverse events and generally support the effectiveness of yellow fever vaccination during pregnancy when administered with appropriate clinical judgment. In high-risk settings, the benefits of maternal immunization clearly outweigh theoretical concerns, supporting a flexible, risk-based approach, despite relatively limited evidence. We also discuss national and international policies, post-pregnancy booster recommendations, and the importance of integrating vaccination assessment into antenatal care. Finally, we highlight critical knowledge gaps and research priorities, including the need for prospective registries and strengthened pharmacovigilance. Coordinated clinical and public health strategies are essential to protect maternal and neonatal health and to reduce the burden of yellow fever in endemic and re-emerging settings.