Presence of Flavivirus Antibodies Does Not Lead to a Greater Number of Symptoms in a Small Cohort of Canadian Travelers Infected with Zika Virus

Abstract

Zika virus (ZIKV) is a mosquito-borne flavivirus associated with a febrile illness as well as severe complications, including microcephaly and Guillain-Barré Syndrome. Antibody cross-reactivity between flaviviruses has been documented, and in regions where ZIKV is circulating, dengue virus (DENV) is also endemic, leaving the potential that previous exposure to DENV could alter clinical features of ZIKV infection. To investigate this, we performed a retrospective case-control study in which we compared Canadian travellers who had been infected with ZIKV and had serological findings indicating previous DENV or other flavivirus exposure (n = 16) to those without any previous exposure (n = 44). Patient samples were collected between February 2016 and September 2017 and submitted to Public Health Ontario for testing. ZIKV infection was determined using real-time RT-PCR and antibodies against DENV were identified by the plaque-reduction neutralization test. The mean time from symptom onset to sample collection was 5 days for both groups; the magnitude of viremia was not statistically different (Ct values: 35.6 vs. 34.9, p-value = 0.2). Clinical scores were also similar. Our findings indicate that previous DENV or other flavivirus exposure did not result in greater viremia or a higher illness score.

Zika virus screening during pregnancy: Results and lessons learned from a screening program and a post‐delivery follow‐up analysis (2016–2022)

“…In spite of this, there is no clear correlation between the intensity of ZIKV infection symptoms among exposed pregnant women and the risk of fetal microcephaly. Cases of newborns with microcephaly whose mothers were asymptomatic or experienced only mild infections are not rare (Kozak et al, 2020; Sornjai et al, 2018; Wilson et al, 2017). Consequently, serology‐based screening programs for pregnant women exposed to ZIKV based on IgM/IgG serology have been implemented in most of the European Union countries, irrespective of the presence of symptoms (Agència de Salut Pública de Catalunya, 2015; Ministry of Health from Spain, 2016).…”