Seroprevalence of dengue in blood donors in an outbreak: experience of a blood bank in north India

Asymptomatic dengue infection rate: A systematic literature review

Objectives

Dengue infection is spreading worldwide. The clinical spectrum is broad and includes asymptomatic infections. This review provides an overview of the different proportions of asymptomatic infections described in epidemiological studies according to definitions, study designs, and detection methods.

Methods

Medline and Embase databases were searched without restriction of date or language. Studies were included if they reported data on the incidence or prevalence of asymptomatic dengue infections. The data were summarized and classified according to the definitions of the term 'asymptomatic'.

Results

A total of 74 studies were included. The mean proportion of asymptomatic infections among dengue-infected persons was 54% in 50 included studies. The prevalence of dengue infections detected in healthy persons was 0.2% in 24 included studies. The term 'asymptomatic' has been used to refer to 'clinically undetectable infection', but also to 'undiagnosed infection' or 'mild infection'. Only 8% were clinically undetectable laboratory-confirmed dengue infections.

Conclusion

The proportion of asymptomatic dengue infections varied greatly. Studies proving data on clinically undetectable laboratory-confirmed dengue infections were very few, but provided consistent results of low proportions of asymptomatic infections. These data challenge the assumption that the majority of dengue cases are asymptomatic.

Epidemiology of Indigenous Dengue Cases in Zhejiang Province, Southeast China

Objective

Autochthonous transmission of the dengue virus (DENV) occurred each year from 2014 to 2018 in Zhejiang province, and became an emerging public health problem. We characterized the autochthonous transmission of the DENV and traced the source of infection for further control and prevention of dengue.

Methods

Descriptive and spatiotemporal cluster analyses were conducted to characterize the epidemiology of autochthonous transmission of the DENV. Molecular epidemiology was used to identify the infection source.

Results

In total, 1,654 indigenous cases and 12 outbreaks, with no deaths, were reported during 2004–2018. Before 2017, all outbreaks occurred in suburban areas. During 2017–2018, five out of eight outbreaks occurred in urban areas. The median duration of outbreaks (28 days) in 2017–2018 was shortened significantly (P = 0.028) in comparison with that in 2004–2016 (71 days). The median onset-visiting time, visiting-confirmation time, and onset-confirmation time was 1, 3, and 4 days, respectively. The DENV serotypes responsible for autochthonous transmission in Zhejiang Province were DENV 1, DENV 2, and DENV 3, with DENV 1 being the most frequently reported. Southeast Asia was the predominant source of indigenous infection.

Conclusions

Zhejiang Province witnessed an increase in the frequency, incidence, and geographic expansion of indigenous Dengue cases in recent years. The more developed coastal and central region of Zhejiang Province was impacted the most.

Prevalence of dengue NS1 antigenemia among healthy blood donors in a tertiary care hospital in Southern India

INTRODUCTION:

Transmission of dengue by transfusion of blood products has been documented, although the frequency of these occurrences and the level of viremia required to cause clinical dengue are unknown. The primary objective was to assess the prevalence of dengue NS1 antigen among healthy blood donors at our blood center.

METHODOLOGY:

This was a cross-sectional study conducted in the Department of Transfusion Medicine, a tertiary care hospital in South-eastern India, from February 2019 to January 2020. A total of 968 donor samples were included in the study. Dengue NS1 antigen detection was done using enzyme-linked immunosorbent assay. Data regarding clinical, epidemiological, and demographic characteristics were collected from the donor questionnaire and records.

RESULTS:

In the study, the overall prevalence of Dengue NS1 antigen was 0.9%, with nine positive samples among the 968 samples tested. Eight of them were male, and 1 was a female donor. All of them were in the age group <32 years. Half of the positive donors were detected during December-January, the immediate post rainy season in this part of the country. Two-third of the positive donors were from rural areas.

CONCLUSION:

This study with a 0.9% throws light on the seroepidemiological prevalence of dengue among asymptomatic donors and gives an insight into whether dengue screening is required to be implemented in routine transfusion transmissible infection screening in blood transfusion services and shall assist in devising strategies to be adapted as to improve the blood safety.

Transfusion-transmissible dengue infections

Dengue is an important global health problem and is endemic in many developing and developed countries. Transmission of dengue may occur in several ways and information on transfusion-transmitted dengue is limited. We conducted a literature search on transfusion-related dengue using the PubMed, Scopus, Embase and Google Scholar databases and have summarized the findings. A number of apparently healthy blood donors have been found to be infected with the dengue virus (DENV) and thus may transmit the virus onto recipients of this blood. It is not possible to identify and exclude such donors at the donor selection stage and thus reliable screening tests should be available in highly endemic areas to ensure a safe blood supply.

Spatiotemporal Distribution of Dengue and Chikungunya in the Hindu Kush Himalayan Region: A Systematic Review

The risk of increasing dengue (DEN) and chikungunya (CHIK) epidemics impacts 240 million people, health systems, and the economy in the Hindu Kush Himalayan (HKH) region. The aim of this systematic review is to monitor trends in the distribution and spread of DEN/CHIK over time and geographically for future reliable vector and disease control in the HKH region. We conducted a systematic review of the literature on the spatiotemporal distribution of DEN/CHIK in HKH published up to 23 January 2020, following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. In total, we found 61 articles that focused on the spatial and temporal distribution of 72,715 DEN and 2334 CHIK cases in the HKH region from 1951 to 2020. DEN incidence occurs in seven HKH countries, i.e., India, Nepal, Bhutan, Pakistan, Bangladesh, Afghanistan, and Myanmar, and CHIK occurs in four HKH countries, i.e., India, Nepal, Bhutan, and Myanmar, out of eight HKH countries. DEN is highly seasonal and starts with the onset of the monsoon (July in India and June in Nepal) and with the onset of spring (May in Bhutan) and peaks in the postmonsoon season (September to November). This current trend of increasing numbers of both diseases in many countries of the HKH region requires coordination of response efforts to prevent and control the future expansion of those vector-borne diseases to nonendemic areas, across national borders.