Introduction

Zika virus (ZIKV) is a mosquito-borne flavivirus that is closely related to yellow fever and dengue viruses and can be transmitted by the bite of an infected Aedes aegypti mosquito, through sexual contact 123 or from mother to fetus 4 . The first large outbreaks, were not reported until 2007 from the Island of Yap in Micronesia and in May 20155, the World Health Organization reported the first local transmission of ZIKV in the north east of Brazil6. Since this initial detection, this virus has spread extensively throughout the Americas678910111213.

Although ZIKV infections have not historically been regarded as a significant public health concern, during this recent emergence, the virus has been linked to neurological disorders and severe congenital abnormalities. As at July 2017, 48 countries and territories have confirmed autochthonous, vector-borne transmission of ZIKV disease, while five countries have reported sexually transmitted Zika cases. Cases of ZIKV infection have been reported in Suriname since October 2, 2015; this nation, which has 530,000 inhabitants, was one of the first South American countries to report Zika virus infections, after Brazil and Colombia.

Phylogenetic analysis has indicated that the isolated virus belongs to the Asian genotype and appears to be most closely related to a strain that was circulating in French Polynesia in 2013.

This article describes the laboratory based surveillance system in Suriname and the incidence of confirmed cases of ZIKV infection according to sex, age, and spatial and temporal distribution

Methods

General practitioners and public health centers located in different districts of Suriname were asked to send blood samples from suspicious cases to Academic Hospital for molecular diagnosis of Zika virus infection. In particular, in cases involving pregnant women, samples were screened for free upon request. Viral RNA was extracted from blood and urine samples using a RNeasy Mini Kit (Qiagen, Hilden, Germany). An in-house molecular real-time RT-PCR assessment based on an approach detailed by Lanciotti et al.14 was used to confirm all cases. Records from patients with positive results between October 2, 2015, and August 23, 2016, were extracted into a database for epidemiological analyses. Collected data included the date of sample collection, which was used as a proxy for symptom onset; age; gender; and the patient’s district of residence, which was used as a proxy for location. Clinical cases reported by the Suriname Ministry of Health to Pan American Health Organization were compared to the confirmed cases. A clinical case of ZIKV disease was defined as a person with a rash with at least two of the following symptoms: fever higher than 38°C, conjunctivitis (non purulent/hyperemic), arthralgia, myalgia and peri-articular edema.

This analysis is based on data collected during the surveillance and response activities implemented during the ZIKV outbreak in Suriname. All data used in this report were aggregated so that they could not be associated with any specific individual.

Results

A total of 3,502 samples (2,752 blood samples and 750 urine samples) were collected from 3,460 individuals, and laboratory evidence of ZIKV infection was found in 791 cases. The outbreak spread rapidly throughout the country, reaching all 10 different districts in Suriname. The peak of the epidemic was observed in mid-January (W2016-03), with 107 molecularly confirmed cases (Figure 1). The weekly number of confirmed cases followed the same dynamic as clinical cases reported by the Ministry of Health.

Fig. 1: Temporal and spatial distribution of ZIKV cases in Suriname, October 2015-August 2016

Overall, 69.9% (553/791) of ZIKV-positive cases involved women (Table 1).

Table 1

Characteristics of 791 patients with molecular confirmation of Zika virus in Surinam, October 2015 – August 2016.

Characteristics N (%) Incidence per 100,000 population
Sex
Female 553 (69.9) 85.1
Male 238 (30.1) 201.7
Age group
<20 years old 111 (13.7) 55.6
[20-39] 413 (51.2) 242.9
[40-59] 190 (23.6) 160.6
>59 years old 93 (11.5) 147.4
District
Brokopondo 1 (0.2) 12.0
Commewijne 19 (3.3) 60.5
Coronie 5 (8.8) 147.4
Marowoijne 4 (0.7) 19.7
Nickerie 39 (6.9) 113.9
Para 6 (1.1) 24.3
Paramaribo 358 (63.0) 148.6
Saramacca 11 (1.9) 62.9
Sipaliwini 4 (0.7) 10.8
Wanica 121 (21.3) 102.3
Total in Surinam 791 147.7

The majority of ZIKV-positive cases involved patients between 20 and 39 years of age, who accounted for more than 51.2% of cases, reflecting concern about Zika infection during pregnancy that led to the overrepresentation of this population among tested individuals. Small fractions of cases involved patients between 0 and 19 years of age (13.7%) and patients older than 60 years of age (11.5%). More than 60% (358/791) of ZIKV-positive cases were from the district of Paramaribo, which was the first district to report confirmed cases, representing an incidence rate of 1.48 confirmed cases for every 1,000 inhabitants (vs 0.71 for every 1,000 inhabitants in other districts). From October 2, 2015, to November 11, 2015, 11 confirmed cases were reported, all of which were within this district. The outbreak gradually spread to western coastal areas and remained active for an extended period in the western districts of Nickerie and Coronie.

Discussion

A laboratory based surveillance system for ZIKV infections was quickly implemented in Suriname according to the previous experiences with chikungunya and has monitored ZIKV outbreak dynamics in the different territories of the country.

The Zika virus outbreak represents a major public health threat, particularly for fetuses of infected pregnant women. Even if the aforementioned statistics substantially underestimate the total impact of the outbreak in Suriname because they do not account for unreported clinical illnesses or asymptomatic infections, this report provides a simple and comprehensive description of the outbreak in Suriname and demonstrates the utility of Zika-related laboratory data to highlight the spatiotemporal dynamics of the outbreak in that country. Although the number of involved pregnant women included in the cohort is not available, follow-up of pregnant women who were infected during the outbreak will be critical for improving understanding regarding the spectrum of adverse pregnancy and infant outcomes associated with Zika virus infection and identifying the effects of certain factors, such as the timing of infection during pregnancy.

This report confirms that the timely and passive routine reporting of spatiotemporal information from clinical and laboratory data is critical for determining and communicating infection risks and for implementing risk reduction activities in high-risk areas, especially in the context of a new emerging infectious disease. To adapt prevention messages and activities and improve knowledge, it is essential to rely on a representative multisource surveillance system based on clinical and confirmed cases with particular attention to complications related to neurological disorders, congenital abnormalities and children born from infected mothers.

Competing Interest Statement

Dr. C. Flamand, on behalf of all the authors of the manuscript submitted to PLoS Current Outbreaks declare that no competing interests exist.

Data Availability Statement

Weekly laboratory data used in the article are accessible in Supplementary file S1, representing the minimal dataset publicly available. Since de-identified data in this report will not constitute truly anonymous information considering that in some situations (Date of collection, municipalities, sex, age), it could be possible to subsequently link the de-identified data back to an identifiable individual, access to individual data is restricted. Interested researchers may send requests to the head of laboratory of Academic Hospital in Paramaribo, Dr. John Codrington (johncodrington@hotmail.com) Laboratory Director Academic Hospital, Flustraat #1 P.O. Box 9305 Paramaribo, Suriname ; Tel : 011-597-442222

Supplementary file S1

Zika virus laboratory data, Academic Hospital-Paramaribo, October 2015 – August 2016.

Epi-week Confirmed cases Diagnosis tests
W2015-38 0 10
W2015-39 0 6
W2015-40 2 8
W2015-41 0 7
W2015-42 1 10
W2015-43 3 20
W2015-44 3 31
W2015-45 11 25
W2015-46 11 16
W2015-47 10 28
W2015-48 18 21
W2015-49 20 30
W2015-50 33 34
W2015-51 16 26
W2015-52 22 28
W2015-53 17 28
W2015-01 68 152
W2016-02 56 210
W2016-03 107 350
W2016-04 79 326
W2016-05 46 259
W2016-06 48 226
W2016-07 37 184
W2016-08 21 123
W2016-09 37 184
W2016-10 31 120
W2016-11 23 145
W2016-12 9 56
W2016-13 8 71
W2016-14 6 67
W2016-15 6 58
W2016-16 5 38
W2016-17 2 38
W2016-18 0 40
W2016-19 1 35
W2016-20 6 53
W2016-21 1 38
W2016-22 2 55
W2016-23 3 39
W2016-24 3 29
W2016-25 2 32
W2016-26 4 19
W2016-27 2 26
W2016-28 3 22
W2016-29 1 21
W2016-30 2 38
W2016-31 3 44
W2016-32 2 34

Corresponding Author

Claude Flammand: cflamand@pasteur-cayenne.fr