"The Chikungunya Outbreak in The Bahamas: Epidemiology and Surveillance in 2014"

Background:

Chikungunya (CHIKV), a mosquito borne arbovirus, has been implicated in a recent outbreak in the Caribbean. The first case of CHIKV in the Caribbean was confirmed on Saint Martin, in May 2013 and local transmission was confirmed in many Caribbean countries. Approximately 1.8 million cases of CHIKV were reported in the region as of 2016.

The Bahamas is an island nation in the North Atlantic Ocean.  The first confirmed case of CHIKV was identified in The Bahamas on July 4, 2014. Thereafter, 798 cases of CHIKV were reported to Bahamas Ministry of Health Surveillance Unit (BMOHSU). This study describes the epidemiology, demographic information, clinical features and outcomes of cases reported during the CHIKV outbreak in The Bahamas during 2014.

Methods:

A retrospective study of all cases of suspected and confirmed CHIKV reported to BMOHSU was conducted.  The case definition was fever > 101¡F, arthralgia and any additional symptom of myalgia, headache, rash, fatigue or nausea. Geographic distribution, demographic information, clinical features and laboratory results were recorded. Descriptive statistics was performed using standard socio-demographic variables, symptoms and geographic variables.

Results:

798 cases met the case definition and were reported July-December 2014. 81% of cases were distributed in the capitol, New Providence (NP). Incidence rate was 0.4 per 1000 cases in NP. Residing in urban, densely populated locations was an identified risk. Most cases occurred in females (65%). Mean age was 27 yrs. Age group most affected was children under 9 yrs (30%). Fever (99%), arthralgia (97%), fatigue (69%), headache (65%) and myalgia (52%) were the most common symptoms. (Figure 1). There were 102 (13%) confirmed cases by RT-PCR. No mortalities were reported. Measures to control the mosquito vector, reduce breeding sites and environmental interventions helped to stop the outbreak. The last confirmed case was in December 2014. The outbreak was classified as over in mid 2015. 

Conclusion:

The overall incidence of CHIKV during the outbreak in The Bahamas was low although cases may have been under reported.  

Lessons learned during the CHIKV outbreak such as aggressive mosquito vector control may be applied as similar arthropod outbreaks such as Zika spread throughout the Caribbean.

Figure 1

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