Relevance of Non-communicable Comorbidities for the Development of the Severe Forms of Dengue: A Systematic Literature Review

Abstract

Patients with dengue fever and comorbidities seem to be at higher risk of developing complications and/or severe dengue compared to healthier individuals. This study systematically reviews the evidence related to comorbidities and dengue. A systematic literature review was performed in five databases (EMBASE, PUBMED, Global Health, SciELO, Cochrane) and grey literature for full-text articles since its inceptions until October 10, 2015. A total of 230 articles were retrieved. Sixteen studies were analysed after applying all inclusion and exclusion criteria. Seven case control studies and nine retrospective cohort studies showed that comorbidities may contribute to severe dengue, especially 1) cardiovascular disease, 2) stroke, 3) diabetes, 4) respiratory disease and 5) renal disease, as well as old age. However, due to heterogeneity in studies, the real estimate effect of comorbidities as modifiers of dengue severity could not be established. Further research in regions with high prevalence of dengue infection would contribute to a better understanding of the relevance of comorbidities in severe dengue, especially with a standardised protocol, for outcomes, specific comorbidities, study design—best using prospective designs—and sample sizes.

Increased Hospitalizations for Neuropathies as Indicators of Zika Virus Infection, according to Health Information System Data, Brazil

“…First, we can assume that the virus entered Brazil mainly in this region ( 12 , 20 ) and that, with the spread of the epidemic to other regions, the number of cases of neuropathies will increase in the rest of the country. On the other hand, the theory persists that other risk factors, such as chronic diseases ( 21 ) and co-infections ( 22 , 23 ) might interact with and potentiate neurologic manifestations in individuals infected by the Zika virus. The region had one of the worst droughts in its history during 2010–2013, resulting in contamination of drinking water, food insecurity ( 24 ), and outbreaks of diarrhea across the region ( 25 ), which could have affected the immunity status of the population.…”

The reintroduction of DENV-2 in 2011 in Panama and subsequent outbreak characteristic

“…However these are likely influenced by both specific host and viral factors that act in concert 5 . Severe disease has been associated with: secondary infection with a different serotype 6–8 , host genetic susceptibility 9 , patient co-morbidities 10,11 , specific DENV serotypes and genotypes 8,12–14 , viral load 15 and the immune response induced by the DENV-NS1 protein 16–19 .…”

Prevalence of comorbidities in the Middle East respiratory syndrome coronavirus (MERS-CoV): a systematic review and meta-analysis

“…The cytokine overload related to the Th1 to Th2 shift in severe viral infection when accompanied by the cytokine synthesis that arises from metabolic diseases, both can be detrimental to the endothelium and lead to a range of subsequent complications 22. The potential role of altered innate immunity and the shift in the Th1 (microbicidal action of IFN-γ) to Th2 (anti-inflammatory IL-4, -5, -10 and -13) responses in linking metabolic diseases to severe viral presentation, may be also supported by the high prevalence of allergy observed in fatal viral infections24 and the eosinophilic responses in other infections 25. Furthermore, metabolic disorders impair macrophage and lymphocyte functions with a subsequent status of reduced immune response26 which may render individuals more susceptible to infectious disease…”