Investigation of an outbreak of acute algal-associated dermatoses among artisanal fishermen in Senegal: A one health approach

Abstract

In November 2020, an alert for a "mysterious disease" among fishermen was issued. Fishermen are particularly subjected to dermatoses due to their constant contact with seawater, fish, crustaceans, and fishing equipment that may contain harmful agents. The study aimed to examine the alert, identify the causative agent and suggest preventive and control measures. This was a cross-sectional study of dermatoses in Dakar (Senegal) from October 11 to November 30, 2020, using quantitative and qualitative methods within a 'One Health' approach." The investigation included bacterio-virological, anatomopathological and toxicological examinations. Data were analyzed using Epi info and QGIS (case mapping), We observed all confidentiality measures during the study. A total of 555 cases were diagnosed with an attack rate of 5.4% among fishermen and no deaths were reported. There was a delay in epidemic detection and notification. The epidemic was most prevalent among people from coastal areas. Average age of cases was 22 ± 9 years, and all were male and artisanal fishermen by profession. Patients presented with fever (16%), cutaneous pain (100%) and mucocutaneous lesions (100%) consisting of vesicles, papules and ulcerations localized on exposed areas of the body, external genitalia and oral mucosa, with severe cases (8%). Toxicology revealed the presence of a toxic alga (V. rugosum) in marine equipments. The notion of a sea trip in the 24-48 hours before the onset of the disease was found in 92%. Majority of cases (74%) did not have full personal protective equipment (PPE). The proportion of people without full protection was 83% among those who developed severe forms. People without full protection were more exposed to severe forms than those with full PPE; (OR = 1.818; 95% CI [0.829 - 3.988]). The investigation has linked the epidemic to a probable algal origin. We need to promote the use of personal protective equipment and improve the early warning and notification system.