SPECIAL ISSUE ON CHIKUNGUNYA IN THE REGION OF THE AMERICAS Pan American Journal Brief communication of Public Health Chikungunya virus outbreak in Sint Maarten, 2013–2014 Maria Henry,1 Lorraine Francis,2 Virginia Asin,1 Karen Polson-Edwards,2 and Babatunde Olowokure2 Suggested citation Henry M, Francis L, Asin V, Polson-Edwards K, Olowokure B. Chikungunya virus outbreak in Sint Maarten, 2013–2014. Rev Panam Salud Publica. 2017;41:e61. ABSTRACT This report describes the outbreak of chikungunya virus (CHIKV) in Sint Maarten, a con- stituent country of Kingdom of the Netherlands comprising the southern part of the Caribbean island of Saint Martin, from 22 December 2013 (first reported case) through 5 December 2014. The outbreak was first reported by the French overseas collectivity of Saint-Martin in the northern part of the island—the first site in the Americas to report autochthonous transmission of CHIKV. By 5 December 2014, Sint Maarten had reported a total of 658 cases—an overall attack rate of 1.76%. Actual prevalence may have been higher, as some cases may have been misdiagnosed as dengue. Fever and arthralgia affected 71% and 69% of reported cases respectively. Of the 390 laboratory-confirmed cases, 61% were female and the majority were 20–59 years old (mean: 42; range: 4–92). The spread of CHIKV to Sint Maarten was inevitable given the ease of movement of people, and the vector, island-wide. Continuing their history of collaboration, the French and Dutch parts of the island coordinated efforts for prevention and control of the disease. These included a formal agreement to exchange epidemiological information on a regular basis and provide alerts in a timely manner; collaboration among personnel through joint island-wide plan- ning of mosquito control activities, especially along borders; notification of all island visi- tors, upon their arrival at airports and seaports, of preventative measures to avoid being bitten by mosquitoes; dissemination of educational materials to the public; and island-wide public awareness campaigns, particularly in densely populated areas, for both residents and visitors. The information provided in this report could help increase understanding of the epidemiological characteristics of CHIKV and guide other countries dealing with vec- tor-borne epidemics. Keywords Chikungunya virus; chikungunya fever; communicable diseases, emerging; Caribbean Region; Americas. Chikungunya virus (CHIKV) is a Tanzania in 1953, the virus has been iden- for weeks, months, or years (3). General mosquito-borne virus (Alphavirus tified in well-documented outbreaks in complications include myocarditis, hepa- genus, Togaviridae family). First isolated in Africa, Asia, and the Pacific (1). Cases titis, and ocular and neurological disor- of CHIKV have also been reported in ders (2). Detection and diagnosis of the 1 General Health Care Section, Department of northern Italy (2007), Thailand (2009), the disease can be challenging, especially in Collective Prevention Services, Ministry of Democratic Republic of Congo (2011), and settings where dengue is endemic. Public Health, Social Development and Labour, Cambodia (2012) (2). CHIKV is transmit- The first evidence of autochthonous Philipsburg, Sint Maarten. Send correspondence to: Maria Henry, Maria.henry@sintmaartengov. ted by the bite of Aedes mosquitoes— transmission of CHIKV in the Americas org mainly A. aegypti and A. ­albopictus. Typical was reported to have occurred in 2 Surveillance, Disease Prevention and Control, Caribbean Public Health Agency, Port-of-Spain, clinical signs of the disease include fever the French overseas collectivity of Trinidad and Tobago. and severe arthralgia, which may persist Saint-Martin, the northern 60% of Rev Panam Salud Publica 41, 2017 1 Brief communication Henry et al. • Chikungunya virus outbreak in Sint Maarten, 2013–2014 the Caribbean island of Saint Martin. The reverse transcriptase real-time PCR (RT- (range: 4–92) and the largest proportion report was submitted on 6 December 2013 qPCR) and serology (IgM) testing to sup- of them (99 or 25%) were in the 40–49 by the French National Reference Labora- port differential diagnoses. Although a year age group (Figure 1). tory, (Regional Health Agency (Agence dengue epidemic was ongoing at the No fatalities associated with chikun- Régionale de Santé, ARS) of Guadeloupe, time, negative laboratory tests suggested gunya infection were reported during Saint-Martin, and Saint Barthélemy (“St. a cause other than dengue virus. CHIKV this period. Major clinical characteristics Barts”), Hope Estate, Saint-Martin). The was detected in the three cases that tested experienced by patients were fever (71%) infection occurred in the district of Oyster negative for dengue by the ARS of and arthralgia (69%). Rash was experi- Pond, which overlaps with Sint Maarten, Guadeloupe, Saint-Martin, and St. Barts, enced by 19% of patients. the Dutch constituent country that com- using RT-qPCR. The date of onset of ill- prises the southern part of the island (4). ness and travel history were not avail- DISCUSSION Sint Maarten reported its first case of able. Subsequent samples from suspected CHIKV on 22 December 2013 (5). cases were tested at the Netherlands Na- Sint Maarten’s well-established syn- Dengue is endemic to the island, and tional Institute for Public Health and the dromic surveillance system, which in- although a dengue epidemic was ongoing Environment (Rijksinstituut voor Volksge- cludes seven sentinel sites countrywide, at the time, negative laboratory tests sug- zondheid en Milieu, RIVM) (Bilthoven, reports data to the VSA’s Department gested a cause other than dengue virus. Kingdom of the Netherlands). Data were of Collective Prevention Services. The This report describes the outbreak of summarized using descriptive statistics surveillance data showed an increase in CHIKV in Sint Maarten through 5 De- from analyses performed on a database UDF beginning in EW5 2014 compared cember 2014. The information provided created using Microsoft Excel (Microsoft, to the four-week 2010–2013 average. His- below could help increase understand- Redmond, Washington, United States). torically, fewer than five cases of UDF ing of the epidemiological characteristics per week were reported during 2010– of this emerging infectious disease and RESULTS 2013, compared to 1–23 cases during guide other countries dealing with vec- 2014. Despite the concurrent outbreak of tor-borne epidemics. No significant rise in reported cases of dengue, the increase in reported cases of UDF was noted in national surveillance UDF was likely due to CHIKV, as labora- MATERIALS AND METHODS data during December 2013. However, an tory tests for dengue were negative. increase in reported cases was detected The CHIKV attack rate in Sint Maarten Surveillance for CHIKV cases in Sint for epidemiological week 5 (EW5) of 2014 (1.76%) was much lower than that of Maarten began on 8 December 2013, (week beginning 26 January 2014). From other documented outbreaks (6, 7). Some two days after the first suspected cases 6 December 2013 to 5 December 2014, Sint Maarten residents with UDF symp- were reported in the French part of a total of 658 chikungunya cases were toms (suspected CHIKV) were diag- the island. Syndromic surveillance is reported, for an overall attack rate of nosed by physicians in the French part well-established in Sint Maarten, with 1.76% (population 37 427; 2011 census). Of of the island, which may have skewed seven sentinel sites throughout the coun- these, 390 were laboratory confirmed, this rate. Residents from Sint Maarten try reporting cases of undifferentiated with 272 (70%) confirmed by RT-qPCR have access to health care services in fever (UDF) to the General Health Care and 118 (30%) by serologic methods. No Saint-Martin and vice versa. There is no Section of the Department of Collective concurrent cases of dengue and CHIKV physical or ecological barrier separating Prevention Services at the Ministry of were detected during that period. the French and Dutch parts of the island, Public Health, Social Development and Of the 390 confirmed cases, 238 (61%) enabling the free movement of people Labour (Ministerie van Volksgezondheid, were female and 149 (38%) were male. and vectors. The two countries have Sociale Ontwikkeling en Arbeid Zaken, Three cases (1%) did not have data on a history of collaborating to address VSA) in Philipsburg. The cases were then gender. Patients’ mean age was 42 years common issues and this cooperation investigated for chikungunya infection. CHIKV case data were collected using an epidemiological survey form with FIGURE 1. Distribution of age and sex for laboratory-confirmed cases of chikungunya questions about demographic informa- virus, Sint Maarten, 6 December 2013–5 December 2014 tion, clinical features, contact history, and travel history. The case definition used 60 for detecting and reporting suspected Male Female Unknown cases was acute fever (> 38.5ºC) accompa- 50 nied by joint pain, with no other aetiol- 40 ogy for the joint pain (3). Laboratory confirmation required demonstration of a 30 positive polymerase chain reaction (PCR) 20 or a positive virus- specific immunoglob- ulin M (IgM) enzyme-linked immunosor- y-confirmed chikungunya cases 10 bent assay (ELISA) antibody test (3). 0 Dengue is endemic to the island and both 0–9 10–19 20–29 30–39 40–49 50–59 60–69 70–79 80–99 Unknown Laborator Saint-Martin and Sint Maarten have the Age group (years) capacity to perform dengue quantitative Source: Prepared by the authors based on the study results. 2 Rev Panam Salud Publica 41, 2017 Henry et al. • Chikungunya virus outbreak in Sint Maarten, 2013–2014 Brief communication was evident with the 2014 signing of a weeks, months, or years, is an increased practitioners (GPs) across Sint Maarten Declaration of Intent to work together to burden on health and social services. were provided with information regard- combat CHIKV (8). Officials from both In response to the outbreak, risk com- ing the disease, and surveillance activities countries agreed to exchange epidemio- munication messages were disseminated by the VSA were enhanced.