Patients with acute dengue who present with high serum chymase levels are at greater risk of dengue hemorrhagic fever or dengue shock syndrome. The chymase level is a prognostic biomarker of severe dengue for adult and pediatric patients before they develop clinical warning signs.

The prognosis of dengue remains a challenge in the early, objective triage of patients with dengue fever of differing severity. Circulating immuno-modulating proteins have brought new possibilities as prognostic markers of severe dengue (SD). This systematic review is devoted to understanding the potential utility of blood-based cytokines and chemokines as prognostication markers of SD based on the current literature. PubMed and Embase were searched. Of 794 candidate articles, 685 abstracts were screened against our exclusion/inclusion criteria and 25 (3.6 %) studies met the quality assessments. A total of 18 studies were retrospective observational and 2 were prospective cohort studies. Elevated IL-10, up to day 7 of fever onset, stood out as a candidate prognostic marker for SD using the 1997 and 2009 World Health Organization (WHO) case definitions. IFNg was another potential prognostic marker of SD (1997 WHO case definition), but its levels varied between studies. Significant heterogeneity in methodologies and patient cohorts prevent ready application of IL-10 and IFNg as prognostic markers to other dengue populations. Our results suggest that the current non-randomized studies are delivering inconsistent messages and higher-quality studies, with consistent methodologies and validation in independent patient cohorts, are needed to delineate confounding variables. Major gaps identified were full accounting and transparency of sampling days, dengue virus type, infection status and age group.

Mobility patterns and travel volumes can help to identify the most likely origin of importation, and also in predicting further propagation. Studies on pregnant returning travellers have contributed to a better understanding of the risk estimates of congenital Zika syndrome/microcephaly as a result of maternal ZIKV infection, and the relative contribution of sexual transmisison.

Rapid increase in trade and a growing air passenger market encourages high travel volume between the regions associated with increasing risks of such importations including China. Eleven Chinese workers infected during the 2016 yellow fever (YF) outbreak in Angola imported YF into China highlighting the potential for spread into Asia. Using outbound and inbound travel data, we assessed travel patterns from and to YF endemic countries in relation to China. Among YF endemic countries, Angola has the second highest number of travellers into China and also receives the second highest number of Chinese visitors. We estimated that China needs around half a million YF vaccine doses to cover their population travelling to YF endemic countries. The recent importation cases into China also unmasked the low YF vaccination coverage among Chinese travellers and workers to Angola, indicating the need to ensure better adherence to the International Health Regulations.

To investigate to what extent asymptomatic vs symptomatic prenatal Zika virus infections contribute to birth defects, we identified 3 prospective and 8 retrospective studies. The ratio varied greatly in the retrospective studies, most likely due to recruitment and recall bias. The prospective studies revealed a ratio of 1:1 for asymptomatic vs symptomatic maternal Zika infections resulting in adverse fetal outcomes.