Dengue seroprevalence among asymptomatic blood donors during an epidemic outbreak in Central-West Brazil

Abstract

Dengue virus (DENV) transmission by blood transfusion is an important route of viral acquisition during outbreaks. The prevalence of DENV markers (viral RNA, NS1, anti-DENV IgM, and IgG) among blood donors in Central-West Brazil has never been evaluated. Our aim was to evaluate the full set of serological and molecular markers for DENV among blood donors of the Federal District of Brazil during an extensive outbreak in 2016. We found an anti-DENV IgM prevalence of 6.74% (n = 32/475). Of 475, 20 samples (4.21%) were also anti-DENV IgG positive. All samples were non-reactive for NS1 and DENV RNA. Our results imply that a significant proportion of the tested donors had experienced asymptomatic infection. More studies are necessary to evaluate the real prevalence of DENV viremia in blood donors from the Federal District of Brazil and if specific measures are needed to routinely test the blood donors for DENV RNA during outbreaks.

High seroprevalence of anti-DENV IgM in blood donors in an early outbreak in the Federal District of Brazil, 2019

“…We observed a prevalence of 16 % of anti-DENV IgM. In 2016, the prevalence observed in the same region for anti-DENV IgM was 6.7 % [8]. In 2019, the Federal District of Brazil had 47 393 probable cases of DENV, according to the Epidemiological Surveillance Bulletin, versus 24 019 probable cases of DENV in 2016.…”

“…In a previous study, we evaluated the prevalence of DENV markers in blood donors during an outbreak in the Federal District of Brazil in 2016 [8]. In this study, we re-evaluated some DENV markers in a representative number of blood donors during the outbreak of 2019, the largest outbreak after 2016 to date.…”

“…An online epidemiology calculator for test proportions was used (https://www.openepi.com/) to calculate an appropriate sample size to be tested [confidence interval (CI): 95 %; desired precision ±3 %]. Considering a study of DENV seroprevalence in blood donors from the Federal District of Brazil during a previous outbreak [8], we adopted a maximum true estimated prevalence of 6.75 % for anti-DENV IgM and 0.63 % for DENV NS1. We calculated that minimum sample sizes of 264 for anti-DENV IgM and 27 for DENV NS1 analyses were required.…”

Zika virus RNA surveillance in blood donors in the Federal District of Brazil during the 2016 outbreak

“…This might have contributed to the lower number of asymptomatic infections in blood donors and a negative PCR result in our study. During the study period, a higher DENV circulation was also reported as evaluated by the high anti-DENV IgM prevalence detected among blood donors, 11 an infection which might have played a prominent role during the study period. Our results may also mean that when our study took place, the ZIKV outbreak may not have fully affected the Federal District of Brazil, thus differing from the ZIKV outbreaks reported in Southeast and Northeast Brazil.…”

Using the intrinsic growth rate of the mosquito population improves spatio-temporal dengue risk estimation

“…people tested after onset of symptoms, and therefore ignores the characteristics and patterns of dengue infections (ascertained from a serosurveillance campaign by Li and colleagues ( Li et al., 2019 )). In fact, a great proportion of infections are likely to be asymptomatic ( Slavov et al., 2019 ) and the incidence of dengue cases doesn't necessarily correlate with the underlying transmission intensity ( Perkins et al., 2014 ). In addition, we cannot unrealistically assume that all the infections originated at household location/proximity without considering other important variables that may have played a role in the geographic ranges of dengue transmission, such as house quality and socioeconomic conditions ( Farinelli et al., 2018 ; Lippi et al., 2018 ) or human behaviour and mobility (shopping, schooling for example)( Stoddard et al., 2013 ; Chuang et al., 2018 ; Kraemer et al., 2018 ; Sanna et al., 2018 ; Wen et al., 2018 ).…”