Dengue 1 outbreak in Rosso, northern Senegal, October 2021: entomologic investigations

Babacar Diouf, Alioune Gaye, Idrissa Dieng, Cheikh Tidiane Diagne, El Hadj Ndiaye, Moufid Mhamadi, Assiyatou Gueye, Oumar Ndiaye, Ndeye Marie Sene, Faty Amadou Sy, Oumar Faye, Ibrahima Dia, Scott C. Weaver, Mawlouth Diallo, Diawo Diallo

Research output: Contribution to journalArticlepeer-review


Senegal has experienced periodic epidemics of dengue in urban areas with increased incidence in recent years. However, few data are available on the local ecology of the epidemic vectors. In October 2021, a dengue outbreak was reported in northern Senegal to the Institute Pasteur de Dakar. Entomologic investigations then were undertaken to identify the areas at risk of transmission and to identify the vector(s). Adult mosquitoes were collected indoors and outdoors at selected households, while containers with water were inspected for mosquito larvae. All the Aedes aegypti (L.) collected were tested for dengue virus NS1 protein using a rapid diagnostic test (RDT), and positive samples were confirmed by real-time RT–PCR. The qRT–PCR positive samples were subjected to whole genome sequencing using Nanopore technology. The majority of the larvae-positive containers (83.1%) were used for water storage. The Breteau and Container indices exceeded the WHO-recommended thresholds for the risk of dengue virus transmission except at 2 localities. Ae. aegypti, the only reputed dengue vector, was collected resting indoors as well as outdoors and biting during the day and night. The NS1 protein was detected in 22 mosquito pools, including one pool of females emerging from field-collected larvae. All NS1-positive results were confirmed by RT-PCR. Virus serotyping showed that the outbreak was caused by DENV-1. This study demonstrates the need for continuous control of adult and aquatic stages of Ae. aegypti to prevent future dengue epidemics in Senegal. RDTs appear to be a promising tool for dengue diagnostics and surveillance.

Original languageEnglish (US)
Pages (from-to)222-232
Number of pages11
JournalJournal of medical entomology
Issue number1
StatePublished - Jan 1 2024
Externally publishedYes


  • Aedes aegypti
  • DENV-1
  • outbreak
  • Rosso
  • Senegal

ASJC Scopus subject areas

  • General Medicine


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