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The Zika pandemic sparked intense interest in whether immune interactions among dengue virus serotypes 1 to 4 (DENV1 to -4) extend to the closely related Zika virus (ZIKV). We investigated prospective pediatric cohorts in Nicaragua that experienced sequential DENV1 to -3 (2004 to 2015), Zika (2016 to 2017), and DENV2 (2018 to 2020) epidemics. Risk of symptomatic DENV2 infection and severe disease was elevated by one prior ZIKV infection, one prior DENV infection, or one prior DENV infection followed by one ZIKV infection, compared with being flavivirus-naïve. By contrast, multiple prior DENV infections reduced dengue risk. Further, although high preexisting anti-DENV antibody titers protected against DENV1, DENV3, and ZIKV disease, intermediate titers induced by previous ZIKV or DENV infection enhanced future risk of DENV2 disease and severity, as well as DENV3 severity. The observation that prior ZIKV infection can modulate dengue disease severity like a DENV serotype poses challenges to development of dengue and Zika vaccines.

Dengue virus (DENV) is the most prevalent human vector-borne viral disease. The force of infection (FoI), the rate at which susceptible individuals are infected in a population, is an important metric for infectious disease modeling. Understanding how and why the FoI of DENV changes over time is critical for developing immunization and vector control policies. We used age-stratified seroprevalence data from 12 years of the Pediatric Dengue Cohort Study in Nicaragua to estimate the annual FoI of DENV from 1994 to 2015. Seroprevalence data revealed a change in the rate at which children acquire DENV-specific immunity: in 2004, 50% of children age >4 years were seropositive, but by 2015, 50% seropositivity was reached only by age 11 years. We estimated a spike in the FoI in 1997-1998 and 1998-1999 and a gradual decline thereafter, and children age

Zika virus (ZIKV) is a mosquito-borne flavivirus that is responsible for recent explosive epidemics in the Americas. Notably, ZIKV infection during pregnancy has been found to cause congenital birth defects, including microcephaly, and ZIKV has been associated with Guillain-Barré syndrome in adults. Diagnosis and surveillance of Zika in the Americas have been challenging due to similar clinical manifestations and extensive antibody cross-reactivity with endemic flaviviral diseases, such as dengue. We evaluated four serological and two reverse transcription-PCR (RT-PCR) methods in acute-phase (mean day, 1.8), early-convalescent-phase (mean day, 16.7), and late-convalescent-phase (mean, ~7 months) samples from the same individuals in a long-term pediatric cohort study in Nicaragua. Well-characterized samples from 301 cases of Zika, dengue, or non-Zika, nondengue febrile illnesses were tested. Compared to a composite reference, an in-house IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) and the NIAID-Biodefense and Emerging Infections (BEI) MAC-ELISA measuring IgM yielded sensitivities of 94.5% and 70.1% and specificities of 85.6% and 82.8%, respectively. The NS1 blockade-of-binding ELISA measuring anti-ZIKV NS1 antibody levels yielded sensitivities of 85.0% and 96.5% and specificities of 91.4% and 92.6% at early and late convalescence, respectively. An inhibition ELISA detecting total anti-ZIKV antibodies had sensitivity and specificity values of 68.3% and 58.3% for diagnosis and 94.0% and 98.6% for measuring annual infection incidence. Finally, the ZCD and Trioplex real-time RT-PCR assays detecting Zika, chikungunya, and dengue viruses both yielded a sensitivity of 96.1% and specificity of 100%. Together, these assays resolve the urgent need for diagnostic and surveillance tools for countries affected by Zika virus infections.

Background Zika virus (ZIKV) emerged in northeast Brazil in 2015 and spread rapidly across the Americas, in populations that have been largely exposed to dengue virus (DENV). The impact of prior DENV infection on ZIKV infection outcome remains unclear. To study this potential impact, we analyzed the large 2016 Zika epidemic in Managua, Nicaragua, in a pediatric cohort with well-characterized DENV infection histories. Methods and findings Symptomatic ZIKV infections (Zika cases) were identified by real-time reverse transcription PCR and serology in a community-based cohort study that follows approximately 3,700 children aged 2-14 years old. Annual blood samples were used to identify clinically inapparent ZIKV infections using a novel, well-characterized serological assay. Multivariable Poisson regression was used to examine the relation between prior DENV infection and incidence of symptomatic and inapparent ZIKV infection. The generalized-growth method was used to estimate the effective reproduction number. From January 1, 2016, to February 28, 2017, 560 symptomatic ZIKV infections and 1,356 total ZIKV infections (symptomatic and inapparent) were identified, for an overall incidence of 14.0 symptomatic infections (95% CI: 12.9, 15.2) and 36.5 total infections (95% CI: 34.7, 38.6) per 100 person-years. Effective reproduction number estimates ranged from 3.3 to 3.4, depending on the ascending wave period. Incidence of symptomatic and total ZIKV infections was higher in females and older children. Analysis of the effect of prior DENV infection was performed on 3,027 participants with documented DENV infection histories, of which 743 (24.5%) had experienced at least 1 prior DENV infection during cohort follow-up. Prior DENV infection was inversely associated with risk of symptomatic ZIKV infection in the total cohort population (incidence rate ratio [IRR]: 0.63; 95% CI: 0.48, 0.81; p < 0.005) and with risk of symptomatic presentation given ZIKV infection (IRR: 0.62; 95% CI: 0.44, 0.86) when adjusted for age, sex, and recent DENV infection (1-2 years before ZIKV infection). Recent DENV infection was significantly associated with decreased risk of symptomatic ZIKV infection when adjusted for age and sex, but not when adjusted for prior DENV infection. Prior or recent DENV infection did not affect the rate of total ZIKV infections. Our findings are limited to a pediatric population and constrained by the epidemiology of the site. Conclusions These findings support that prior DENV infection may protect individuals from symptomatic Zika. More research is needed to address the possible immunological mechanism(s) of cross-protection between ZIKV and DENV and whether DENV immunity also modulates other ZIKV infection outcomes such as neurological or congenital syndromes., Author(s): Aubree Gordon 1, Lionel Gresh 2, Sergio Ojeda 2, Leah C. Katzelnick 3, Nery Sanchez 2, Juan Carlos Mercado 2,4, Gerardo Chowell 5, Brenda Lopez 2, Douglas Elizondo 2, [...]

Myopathy caused by steroids is a serious and unusual side effect related with administration of high doses of steroids. In this article we had reported a possible deleterious and serious effect on the mother health when steroids are used in the treatment of preterm childbirth. The case of a pregnant patient of 28 gestational week that consults to the emergency department with signs of preterm birth, receives tocolysis and lung maturation with Betametasona (12 mg the first day and 12 mg at 24 hours after first dose); thereafter, patient refer dizziness and blurry vision, which progress rapidly to pain in lower limbs, with weakness, being generalized then to four limbs, for acute weakness and imminence of respiratory failure the patient was transferred to the intensive care unit (ICU) for respiratory vigilance, possible ventilatory support and study of this weakness. Myopathy caused by steroids is generally related with high doses of steroids. These patients, present a clinical typical picture characterized by widespread weakness of four extremities, muscular atrophy, normal CK or moderately high and myopathic changes in the EMG, the clinical presentation improves slowly. This report invite us to questioning the apparent innocuousness of steroids in pulmonary maturity and the dose of the same one, as well as to using them well in agreement to the indication of the same one keeping in mind the risk - benefit of the medicine.RESUMENLa miopatía causada por esteroides es un efecto secundario grave muy poco frecuente asociado a la administración de dosis altas de esteroides. Se reportan los posibles efectos deletéreos sobre la salud materna que puede tener la administración de corticosteroides frente al riesgo de un parto pretérmino. Se presenta el caso de una paciente gestante de 28 semanas que consulta al servicio de urgencia por infección de vías urinarias y amenaza de parto pretérmino, que recibe uteroinhibicion y maduración pulmonar con Betametasona (12 mg primer día y 12 mg a las 24 horas de primera dosis); luego de segunda dosis de maduración pulmonar la paciente refiere vértigo y visión borrosa, la cual progresó rápidamente a dolor, con pérdida de fuerza muscular en miembros inferiores, generalizándose luego a las cuatro extremidades, por lo que ante la inminencia de falla respiratoria se traslada a unidad de cuidados intermedios para vigilancia ventilatoria y estudio de miopatía.Discusión: La miopatía por esteroides, se produce con dosis altas de corticoides. Estos pacientes, presentan un cuadro clínico típico caracterizado por debilidad generalizada de las cuatro extremidades, atrofia muscular, CK normal o moderadamente elevada y cambios miopáticos en el EMG, el cuadro clínico mejora aunque de forma lenta. Conclusiones: Este reporte nos invita a cuestionar la aparente inocuidad de los esteroides en maduración pulmonar y la dosis de la misma, así como a utilizarlos bien de acuerdo a la indicación del mismo teniendo en cuenta el riesgo – beneficio del medicamento.

Tetanus is a potentially life-threatening infection characterized by muscle spasms. Cephalic tetanus is limited to muscles and nerves in the head and can occur after trauma to this area. Because of the rarity of cephalic tetanus clinicians may be unfamiliar with the clinical presentation unsuspecting of the diagnosis.