Outbreak of Cutaneous Leishmaniasis among military personnel in French Guiana, 2020: Clinical, phylogenetic, individual and environmental aspects

Abstract

Background: Cutaneous Leishmaniasis (CL) is endemic in French Guiana but cases are usually sporadic. An outbreak signal was issued on May 15th 2020 with 15 suspected cases after a military training course in the rainforest. An outbreak investigation was carried out.

Methodology/principal findings: Thirty cases were confirmed. Leishmania guyanensis was the most frequent species (90%). The most frequent presentation was ulcerative (90%). Lesions on the face and hands were frequent (40% each). Eight cases (26%) presented a poor outcome after treatment with pentamidine and required a second line with amphotericin B. Three of them required further treatments with meglumine antimoniate or miltefosine. Two spots within the training area were deemed as likely sites of contamination, due to illegal logging. The isolated Leishmania strains did not form a separate cluster. Participation in Week 13 of year 2020 was associated with infection (OR = 4.59 [1.10-19.83]; p = 0.016) while undergoing only the "Fighting" exercise was protective (OR = 0.1 [0-0.74]; p = 0.021). There was no association between infection and other risk factors at the individual level. The attack rate of Regiment B (14/105 = 13.3%) was significantly higher (OR = 4.22 [1.84-9.53], p = 0.0001) compared to Regiment A (16/507 = 3.2%). The attack rate during this training course (30/858 = 3.5%) was significantly higher (OR 2.29 [1.28-4.13]; p = 0.002) than for other missions in French Guiana during the same period (22/1427 = 1.5%).

Conclusions: This outbreak could be explained by a combination of factors: climatic conditions around week 13, at-risk activities including night trainings, absence of impregnation, a lesser experience of rainforest duties in Regiment B and illegal logging attracting sandflies on military training grounds.

Fig 1. Flow chart of patients respectively included in the clinical description of cases, phylogenetic analysis and case-control study, CEFE outbreak, French Guiana, 2020.

Fig 2

Clinical evolution of patient 1, CEFE outbreak, French Guiana, 2020: initial lesion of the left cheek (2a), which improved after pentamidine; new lesion on the opposite cheek (2b) improved after amphotericin B (2c); new relapse occurred on the right ear and the forehead (2d); after another unsuccessful amphotericin B course and three weeks of meglumine antimoniate (75mg/kg/d), improvement was seen on the face (2e) but disseminated new lesions appeared. Healing was obtained after one month of oral miltefosine (50mg tid).

Fig 3

Clinical evolution of patient 2 and 3, CEFE outbreak, French Guiana, 2020: patient 2 presented an ulceration on the ear and papules of the adjacent cheek (3a); improvement after pentamidine (3b) followed by relapses (3c), requiring a course of amphotericin B, then a second scheme in association with miltefosine (3d), with partial response (3e) followed by a relapse. The patient was then treated with 3 weeks of meglumine antimoniate. Patient 3 presented a similar history with a pseudo-verrucous plaque of the neck (3f), which first improved (3g), and then relapsed (3h) motivating a further line of treatment with amphotericin B, amphotericin B and miltefosine then finally meglumine antimoniate.

Fig 4. Number of confirmed cases of cutaneous leishmaniasis for each calendar week between February and June 2020, CEFE training site, French Guiana, 2020.

Fig 5. Phylogenetic tree of isolated strains and samples used for comparison, CEFE outbreak, French Guiana, 2020; green dots indicate the 26 strains isolated during the outbreak; red squares indicate 25 other strains isolated in French Guiana during the same period; blue triangles indicate 15 references strains used for species identification.

Fig 6. Map of Training Center in Equatorial Forest, CEFE outbreak, French Guiana, 2020, layer from a Guiana Amazonian Park (Parc Amazonien de Guyane) map available at http://cartotheque.parc-amazonien-guyane.fr/index.php/view/map/?repository=pag&project=Limites_PAG.