Key Points

• The latest outbreak lasted nearly a year and a half, from late January 2020 to mid-June 2021, peaking in June 2020. An estimated 10,900 clinically suggestive cases were seen in outpatient clinics; 6,195 probable or confirmed cases were recorded, along with 289 hospitalizations and 3 deaths. At the peak of the outbreak, emergency department visits for suspected dengue accounted for an average of 6% of emergency department activity in French Guiana hospitals. Serotype DEN-1 (84%) was predominant, but DEN-2 also circulated (15%).

• This outbreak occurred concurrently with the COVID-19 outbreak, which began in French Guiana in early March 2020 and whose first wave also peaked in June 2020. Changes in healthcare-seeking behavior, similarities between the clinical presentations of dengue and COVID-19, prioritization of COVID-19 testing, and shortages of reagents are all factors that may have reduced the sensitivity of surveillance. Comparison with previous and subsequent epidemics is therefore difficult, and the number of cases, hospitalizations, and emergency room visits is likely lower than what would have been observed had the COVID-19 pandemic not occurred.

• After a prolonged period of epidemic outbreaks (9 months), the Savanes sector was the first to experience an intensification of viral circulation much earlier than in other sectors, before enduring an epidemic lasting over a year. The differences in epidemic dynamics observed by sector confirm the validity of the territorialization strategy implemented in 2012.

• Since April 2023, French Guiana has seen a resurgence of dengue cases, primarily due to the DEN-3 serotype, across the entire territory and particularly in the Savanes sector, which has been in an epidemic since June. We are already seeing increased pressure on the emergency department at Kourou General Hospital, with visits for suspected dengue accounting for more than 10% of the department’s total activity since mid-August. Serotype DEN-3 has not caused an epidemic in French Guiana for 20 years, which implies low immunity among the population and raises concerns about a large-scale epidemic.