A 37-year-old French male spent 10 days in Mauritius in March 2010, as an independent traveler to the island, together with six friends. During this trip, he experienced mosquito bites. He also had hand-contact with stagnant water in Pamplemousse Botanical Gardens and took part in freshwater swimming activities on two occasions, the first in a waterfall river on the east coast between Trou d’Eau Douce and Grande Rivière, and second, in a waterfall pond, in the southern part of Mauritius close to Chemin-Grenier. Eight days after returning to Marseille, France, he was hospitalized with a 2-day history of fever, chills, myalgia, arthralgia, fatigue, headache, and retro-orbital pain. The time interval between return from endemic area to occurrence of fever was therefore 6 days. The incubation time between suspected exposures and occurrence of fever was 9, 11, and 12 days. His laboratory results on admission are summarized in Table 1. The abdominal echography showed a moderate hepatosplenomegaly. Within 3 days, he exhibited a generalized rash with desquamation and purpura localized to the ankles and was transferred to the Department of Infectious Diseases and Tropical Medicine. The initial working diagnosis was dengue fever, based on clinical and biological features and on the confirmed presence of dengue virus in the neighboring islands.3 The clinical status improved initially under intravenous acetaminophen and rehydration. Blood and urine cultures remained negative. Laboratory findings revealed a transient thrombocytopenia, mild renal dysfunction, and a slight increase in hepatic enzymes (Table 1). Repeated serological and polymerase chain reaction (PCR) assays were all negative for dengue, chikungunya, West Nile virus, and Rift Valley fever. Surprisingly, after 3 days of favorable outcome, the patient developed intense neuralgia of the left nervus trigeminus (V3), which lasted for 5 days. Four days later, he complained of intense abdominal pain that was associated with a sixfold rise in lipase levels (Table 1). This finding was not associated with changes to the hepatobiliary tract on computed tomography (CT) scan. The clinical status improved under fasting and symptomatic treatment. Leptospirosis was diagnosed through the presence of specific immunoglobulin M (IgM) in the blood by enzyme-linked immunosorbent assay (ELISA, >1/6400). The Leptospira icterohaemorrhagiae serogroup was identified by the microagglutination method. The diagnosis was confirmed by detecting Leptospira interrogans DNA in urine samples using PCR, as previously described.4 Serological assays were negative for acute hepatitis A, B, C, and E, human immunodeficiency virus, cytomegalovirus, Epstein–Barr virus, varicella zoster virus, parvovirus, coxsackie virus, legionella, chlamydia, Mycoplasma pneumoniae, campylobacter, Lyme disease, Q fever, and Rickettsia conori infections. The patient was successfully treated with ceftriaxone for 10 days. None of the individuals who traveled with the patient fell ill during their stay in Mauritius and over the weeks following their return to France.