Short communication
Imported dengue from 2013 Angola outbreak: Not just serotype 1 was detected

https://doi.org/10.1016/j.jcv.2016.04.011Get rights and content

Highlights

  • We treated 47 adult patients with dengue imported from Angola’s 2013 outbreak.

  • Predominantly serotype 1 was found, but the 4 serotypes were identified as related.

  • To our knowledge, this is not published in the literature.

  • It seems to us to be a relevant issue in the history of this outbreak.

  • We would like to present these results to the medical community.

Abstract

Background

All the reports from Angola’s 2013 dengue outbreak revealed serotype 1. However, previously dengue serotypes 1–4 have been reported in Africa and in 2014 serotype 4 was reported in Angola.

Objectives

To report dengue serotypes in patients returning from Angola during 2013 outbreak.

Study design

Retrospective, cross-sectional study. We serotyped the dengue by an in house Polymerase Chain Reaction technique in randomly selected cases.

Results

From the 2013 Angola’s dengue outbreak we treated 47 adult patients. None had history of past dengue. A combo kit test for dengue revealed positive NS1 antigen in 39 and IgM antibodies in 8. From 17 randomly patients tested by RNA Real Time-PCR, 11 were positive: 7 for DENV-1, 2 for DENV-2, 1 for DENV-3 (co-infected with DENV-1) and 1 for DENV-4. None had a complicated or fatal evolution.

Conclusion

Unlike previous reports the 4 serotypes were detected, and this resulted in a different epidemiological situation, raising the risk of future outbreaks of severe dengue.

Section snippets

Background

Serosurveys in Africa document the presence of dengue since 1926 [1]. In Africa the surveillance data are poor and its knowledge is not accurate [2]. Despite this, there are reports from serotypes 1, 2, 3 and, more rarely, serotype 4 in several African countries [3], [4], [5], [6].

Angola’s dengue cases have been described in 1986 and 1999–2002 [7], but no dengue outbreak was reported until 2013. All isolates from this outbreak have been consistently reported as serotype 1 [8], [9], [10].

Objectives

To report clinical and laboratory data concerning imported dengue in 2013 in patients returning from Angola.

Methods

We made a hospital-based, retrospective and cross-sectional study, analysing all the clinical and laboratory records of adults returning from Angola and diagnosed with dengue. We used an in-vitro rapid immunochromatographic assay, SD BIOLINE Dengue Duo® (Dengue NS1 Ag + IgG/IgM) kit following the manufacture protocol. From some randomly selected patients the plasma was frozen (−20 °C). Later we tested for Dengue virus RNA and serotyped. We used an in-house one step Reverse Transcription Real Time

Results

From the 47 patients with dengue, 45 were non-Angolan and 20 were expatriate in Angola. No patient had previously reported clinical dengue fever. They all lived or stayed for some days in Luanda, before travelling to Portugal. At diagnosis fever was reported in all patients, myalgia in 40, headache in 37, asthenia in 31, retro-orbital pain in 17 and arthralgia in 15. Gum bleeding and metrorrhagia was elicited in 2 patients.

Discussion

This study addresses for the first time the circulation of the four dengue serotypes in the 2013 Angola’s outbreak. The outbreak was linked to serotype 1 [8]. In Africa very few studies explore the serotypes identification, evolutionary history and dynamic of the disease and there is not any report of these serotypes co-circulating [13]. The detection of the four serotypes in this outbreak may translate a large dissemination of dengue virus.

We screened all the samples with the SD BIOLINE Dengue

Acknowledgements

The authors would like to thank Professor Henrique Lecour for his valuable comments and review of the draft manuscript.

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1

These two authors contributed equally in the design, conception, analysis, and paper writing.

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