Sistema FMUSP-HC: Faculdade de Medicina da Universidade de São Paulo (FMUSP) e Hospital das Clínicas da FMUSPKANUNFRE, Kelly AparecidaROCHA, Mussya CisottoMALTA, Maira BarretoSOUZA, Rodrigo Medeiros deCASTRO, Marcia CaldasBOSCARDIN, Silvia BeatrizSOUZA, Higo Fernando SantosWITKIN, Steven S.CARDOSO, Marly AugustoOKAY, Thelma Suely2022-06-202022-06-202022REVISTA DO INSTITUTO DE MEDICINA TROPICAL DE SAO PAULO, v.64, article ID e25, 8p, 20220036-4665https://observatorio.fm.usp.br/handle/OPI/47200The prevalence of immunity to Chikungunya virus (CHIKV) in pregnant women and newborns in the Western Brazilian Amazon was assessed at a time when previous studies did not report chikungunya fever in the area. In 435 asymptomatic pregnant women and 642 healthy unrelated newborns, the presence of IgM and IgG antibodies to CHIKV were determined by a commercial ELISA. All participants were negative to IgM anti-CHIKV. Anti-CHIKV IgG was identified in 41 (9.4%) pregnant women and 66 (10.3%) newborns. The presence of anti-CHIKV IgG was positively associated with the lowest socioeconomic status in pregnant women (OR 2.54, 95% CI 1.15-5.62, p=0.021) and in the newborns' mothers (OR 5.10, 95% CI 2.15-12.09, p< 0.001). Anti-CHIKV IgG was also associated with maternal age in both, the pregnant women (OR 1.06, 95% CI 1.00-1.11, p=0.037) and the newborns'mothers (OR 1.08, 95% CI 1.03-1.12, p=0.001). Pregnancy outcomes in which the mother or the newborn was anti-CHIKV IgG positive proceeded normally. Negative CHIKV serology was associated with being positive for DENV antibodies and having had malaria during pregnancy. These findings showed that there was already a silent circulation of CHIKV in this Amazon region before the first outbreak of chikungunya fever. Furthermore, seropositivity for CHIKV was surprisingly frequent (10%) in both, pregnant women and newborns, affecting mainly low-income women.engopenAccessCHIKVSeroprevalenceAsymptomatic infectionIgG antibodiesPregnancyNeonatesAmazon regionseroprevalenceimmunoglobulinarticleCopyright INST MEDICINA TROPICAL SAO PAULO10.1590/S1678-9946202264025Biochemistry & Molecular BiologyChemistry, MedicinalFood Science & Technology1678-9946