Epidemiology of skin infection in homeless population in Marseille

Abstract

Purpose: To describe homeless demographics, chronic medical conditions, ectoparasite and vector-borne disease prevalence over a 19 year-period of time. Methods & Materials: Single-day cross sectional surveys were performed from 2000-2018 using standardized questionnaires and clinical examination of 2387 participants. Samples were collected including: Body lice (2000-2018): Detection of Bartonella quintana, Rickettsia spp., Borrelia spp., Acinetobacter spp., Acinetobacter baumannii (qPCR) Human skin (2014) from hair, neck, arm pits, pelvic belt: Acinetobacter spp., Acinetobacter baumannii. Blood (2014): Acinetobacter spp. (qPCR, culture) Detection of Sarcoptes scabiei (2018): physical examination, dermatoscopy, qPCR (skin scrapings) Results: The population was characterized by a majority of males (95.6%) from North African (49.0%) with a relatively high prevalence of chronic homelessness (44.0%). Pruritus (26.5%) and scratch lesions (17.4%) were recorded. The prevalence of body lice (10.2%) significantly decreased overtime (14.4% in 2000; 1% in 2018). Positive associations were reported between body lice infestations and older age, duration of stays in France for migrants, frequent consumption of alcohol, and tobacco smoking during the 2000-2017 time period. During 2013-2018, we observed Bartonella quintana (1%), Rickettsia spp. (0%) and Borrelia spp. (0%) among 588 body lice specimens. In 2014, Acinetobacter baumannii was found in crushed body lice (42.3%). Homeless infested with body lice were at a greater risk of carrying A. baumannii on the skin (OR = 13, p = 0.004); all blood samples were negative for Acinetobacter spp.. In 2018 we found no scabies in homeless sufffering pruritus. Conclusion: The decreasing prevalence of body louse and louse-borne infection in recent years could possibly be due to the changes in the characteristics of the population but also to the effect of delousing interventions conducted in the shelters by our team or by the shelter staff following our recommendations (providing showers, clothes, laundry and ivermectin treatment).For A. baumannii, we found no evidence that lice can transmit the bacteria through blood circulation, suggesting that infection of lice is due to direct contact with the skin rather than blood feeding. Several risk factors for body lice were identified, allowing a better identification of individuals at higher risk on whom to base targeted preventive interventions.