Lack of Zika virus antibody response in confirmed patients in non-endemic countries

Zika Virus Antibody Titers Three Years after Confirmed Infection

Background: In 2015–2016, a large Zika virus (ZIKV) outbreak occurred in the Americas. Although the exact ZIKV antibody kinetics after infection are unknown, recent evidence indicates the rapid waning of ZIKV antibodies in humans. Therefore, we aimed to determine the levels of ZIKV antibodies more than three years after a ZIKV infection. Methods: We performed ZIKV virus neutralization tests (VNT) and a commercial ZIKV non-structural protein 1 (NS1) IgG ELISA in a cohort of 49 participants from Suriname who had a polymerase-chain-reaction-confirmed ZIKV infection more than three years ago. Furthermore, we determined the presence of antibodies against multiple dengue virus (DENV) antigens. Results: The ZIKV seroprevalence in this cohort, assessed with ZIKV VNT and ZIKV NS1 IgG ELISA, was 59.2% and 63.3%, respectively. There was, however, no correlation between these two tests. Furthermore, we did not find evidence of a potential negative influence of DENV immunity on ZIKV antibody titers. Conclusions: ZIKV seroprevalence, assessed with two commonly used serological tests, was lower than expected in this cohort of participants who had a confirmed previous ZIKV infection. This can have implications for future ZIKV seroprevalence studies and possibly for the duration of immunological protection after a ZIKV infection.

Rapid decline of Zika virus NS1 antigen-specific antibody responses, northeastern Brazil

Zika virus (ZIKV) is a positive-stranded RNA virus within the Flaviviridae family. After decades of circulation in Asia, ZIKV was introduced to Brazil in 2014–2015, associated with a rise in congenital malformations. Unlike the genetically related dengue virus (DENV), ZIKV constitutes only one serotype. Although assumed that ZIKV infection may engender lifelong immunity, the long-term kinetics of ZIKV antibody responses are unclear. We assessed long-term kinetics of ZIKV NS1-IgG response in 144 individuals from 3 different subpopulations: HIV patients, tuberculosis patients and healthy individuals first tested in 2016 and retested 1.5–2 years after the 2015–2016 ZIKV epidemic in Salvador de Bahia, Brazil, using a widely distributed NS1-based commercial ELISA. The seropositivity in 2016 reached 59.0% (85/144, 95% confidence interval (CI) 50.7–66.7%), and decreased to 38.6% (56/144, CI 31.3–47.0%) 1.5–2 years later. In addition, the median ZIKV NS1-ELISA reactivity for individuals that remained positive in both timepoints significantly decreased from a ratio of 4.4 (95% CI 3.8–5.0) to 1.6 (95% CI 1.6–1.9) over the 2-year interval (Z: − 6.1; p < 0.001) irrespective of the subpopulation analyzed. Initial 2016 DENV antibody response was non-significant between groups, suggesting comparable DENV background. The high 20.6% seroreversion suggest that widely used serologic tests may fail to account a considerable proportion of past ZIKV infections in flavivirus endemic countries. In addition, ZIKV immunity might be shorter-lived than previously thought, which may contribute to local ZIKV resurgence once individual immune responses wane sufficiently to reduce community protective immunity in addition to birth and migration.

Performance of Zika Assays in the Context of Toxoplasma gondii, Parvovirus B19, Rubella Virus, and Cytomegalovirus (TORCH) Diagnostic Assays

Infections during pregnancy that may cause congenital abnormalities have been recognized for decades, but their diagnosis is challenging. This was again illustrated with the emergence of Zika virus (ZIKV), highlighting the inherent difficulties in estimating the extent of pre- and postnatal ZIKV complications because of the difficulties in establishing definitive diagnoses. We reviewed the epidemiology, infection kinetics, and diagnostic methods used for Toxoplasma gondii, parvovirus B19, rubella virus, and cytomegalovirus (TORCH) infections and compared the results with current knowledge of ZIKV diagnostic assays to provide a basis for the inclusion of ZIKV in the TORCH complex evaluations. Similarities between TORCH pathogens and ZIKV support inclusion of ZIKV as an emerging TORCH infection. Our review evaluates the diagnostic performance of various TORCH diagnostic assays for maternal screening, fetal screening, and neonatal screening. We show that the sensitivity, specificity, and positive and negative predictive value of TORCH complex pathogens are widely variable, stressing the importance of confirmatory testing and the need for novel techniques for earlier and accurate diagnosis of maternal and congenital infections. In this context it is also important to acknowledge different needs and access to care for different geographic and resource settings.

Clinical and neurodevelopmental features in children with cerebral palsy and probable congenital Zika

OBJECTIVE

To describe the neurological and neurodevelopmental features at 1 year of age in children with cerebral palsy (CP) related to probable congenital Zika (CZ), followed in a referral neurorehabilitation hospital.

METHODS

Data on 82 children with CP associated with probable CZ, who consecutively attended the neurodevelopmental and neurological assessment around one year of age, were collected. For neurodevelopmental evaluation, Bayley-III Scales of Infant and Toddler Development was used. Descriptive statistical analysis was performed.

RESULTS

The children were admitted into the rehabilitation program at a young age (mean age: 4.8 months, SD 3.1), followed beyond the first year of life (mean age of follow up: 13.2 months, SD 2.1), born to young mothers (mean age: 28.1 years, SD 5.9), in their first pregnancy (62.2%). The majority had severe congenital microcephaly (62.0%), spastic CP (96.3%), epilepsy (63.4%), absent expected postural reactions (93.2%), abnormal persistence of primitive reflexes (94.7%), and severe neuroimaging abnormalities, predominantly calcifications (97.6%). Extremely low performances on cognitive (95.1%), language (97.6%) and motor (97.6%) developmental composite scores were observed. There was a correlation between the cognitive score with the birth head circumference (HC) (r = 0.3, p = 0.01) and with the follow up HC (r = 0.4, p < 0.01), as well as between the follow up HC with the motor score (r = 0.2, p = 0.03).

CONCLUSION

Congenital Zika may be associated with a severe form of CP, mainly bilateral spastic, with a severe global neurodevelopmental impairment and early signs of a poor prognosis for independent walking. Head circumference may be a prognostic marker among those children. These results may help establish goals for the rehabilitation program and identify priority health services.

Whole-Blood Testing for Diagnosis of Acute Zika Virus Infections in Routine Diagnostic Setting

We evaluated the benefit of whole blood versus plasma to detect acute Zika virus infections. Comparison of Zika virus quantitative reverse transcription PCR results in single timepoint whole blood–plasma pairs from 227 patients with suspected Zika virus infection resulted in confirmation of 8 additional patients with Zika virus infection.

Incidence of Zika virus infection in a prospective cohort of Belgian travellers to the Americas in 2016

BACKGROUND

The incidence rate of Zika virus (ZIKV) infection in travellers from non-endemic areas to the Americas during the ZIKV outbreak in 2016 is unknown.

METHODS

Belgian adults who planned to travel to South America, Central America, and the Caribbean were recruited prospectively to study the incidence and characteristics of ZIKV. Demographic data and sera were collected at baseline. Participants were trained to collect capillary blood on filter paper (BFP). When ill during travel, the participants completed a questionnaire and they sampled BFP for post-hoc analysis. All symptomatic participants were screened for ZIKV using ZIKV-specific RT-PCR on serum or urine, or BFP, and antibody detection assays (ELISA). Follow-up sera of asymptomatic travellers, obtained at least 20 days post travel, were tested by ZIKV ELISA only. All positive ELISA results were subject to confirmation by virus neutralization testing (VNT).

RESULTS

Forty-nine participants completed follow-up: 38 women and 11 men, with a median age of 32 years (range 19-64 years). Travel destinations were countries in South America (n=20), Central America (n=24), and the Caribbean (n=5). The total travel duration was 67.8 person-months. Illness was reported by 24 participants (49.0%). ZIKV infection was confirmed in nine cases, by RT-PCR (n=5) and by VNT (n=4). Only one of nine ZIKV cases (11.1%) was asymptomatic. The ZIKV incidence rate was 17.0% (95% confidence interval 7.8-32.2%) per month of travel.

CONCLUSIONS

The ZIKV incidence rate in adult travellers from non-endemic countries to the epidemic territories during the 2016 outbreak was high. Asymptomatic ZIKV infection was rare in this population.

Zika virus and Guillain-Barré syndrome in Bangladesh

Objective

Previous studies have associated Guillain–Barré syndrome (GBS) with Zika virus (ZIKV) outbreaks in South America and Oceania. In Asia, ZIKV is known to circulate widely, but the association with Guillain–Barré syndrome is unclear. We investigated whether endemic ZIKV infection is associated with the development of GBS.

Methods

A prospective study was conducted from 2011 to 2015 in Bangladesh. A total of 418 patients and 418 healthy family controls were included in the study. Patients were diagnosed with GBS prior to inclusion according to established criteria. Detailed information on the epidemiology, clinical presentation, electrophysiology, diagnosis, disease severity, and clinical course were obtained during a follow‐up of 1 year using a predefined protocol.

Results

ZIKV‐neutralizing antibodies were detected in our study from 2013 onwards. The prevalence of ZIKV‐neutralizing antibodies was not significantly higher in patients with GBS compared to healthy controls (OR 2.23, P = 0.14, 95% CI 0.77–6.53). Serological evidence for prior ZIKV infection in patients with GBS was associated with more frequent cranial, sensory, and autonomic nerve involvement compared to GBS patients with Campylobacter jejuni, the predominant preceding infection in GBS worldwide. Nerve‐conduction studies revealed that ZIKV antibodies were associated with a demyelinating subtype of GBS, while C. jejuni infections were related to an axonal subtype.

Interpretation

No significant association was found between ZIKV infection and GBS in Bangladesh, but GBS following ZIKV infection was characterized by a distinct clinical and electrophysiological subtype compared to C. jejuni infection. These findings indicate that ZIKV may precede a specific GBS subtype but the risk is low.