Silent circulation of Chikungunya virus among pregnant women and newborns in the Western Brazilian Amazon before the first outbreak of chikungunya fever

• Published in: Revista do Instituto de Medicina Tropical de São Paulo
• Main Authors: Kelly Aparecida Kanunfre, Mussya Cisotto Rocha, Maíra Barreto Malta, Rodrigo Medeiros de Souza, Marcia Caldas Castro, Silvia Beatriz Boscardin, Higo Fernando Santos Souza, Steven S. Witkin, Marly Augusto Cardoso, Thelma Suely Okay
• Format: Article in Journal/Newspaper
• Language: English
• Published: Universidade de São Paulo (USP) 2022
• Subjects: CHIKV; Seroprevalence; Asymptomatic infection; IgG antibodies; Pregnancy; Neonates; Amazon region; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1590/s1678-9946202264025; https://doaj.org/article/e704237165964e3db00ff406172088a5

ABSTRACT The 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.