[Five authochthonous cases of dengue deteted in Nice]. Fever Mosaic 1, EuroImmun AG, Lbeck, Germany) against chikungunya virus (CHIKV), DENV and Japanese encephalitis virus (JEV) was performed at the Dutch National Institute for Public Health and the Environment (RIVM) laboratory. High concentrations of DENV-specific IgM and IgG antibodies were detected (Table 2). There was a slight IgG response, without IgM response, against JEV, interpreted as non-specific cross-reactivity. RT-PCR was not done. Table 1 Laboratory findings, dengue Patient 1, France, July 2020 on a 150 m radius) and door-to-door investigations in order to identify other cases and raising awareness among local healthcare professionals and the public [1]. Discussion Here we describe two patients with dengue from the same family, who acquired the disease in Department Var, southern France. The signs and symptoms, as well as the plasmocytosis, of Patient 1 were typical for dengue [2]. The list of differential diagnoses was therefore very short and the high IgM and IgG titres for DENV were considered confirmative, even though definite confirmation would require demonstration of virus or serodiagnosis on paired MC-Val-Cit-PAB-duocarmycin samples [3]. PCR was not conducted to detect DENV in blood or MC-Val-Cit-PAB-duocarmycin urine because the chance for a positive test was considered low in this rather late stage of disease and it was not deemed necessary for confirmation of disease, clinical management, notification or public health measures. Dengue is endemic in large parts of the world and a common illness among returning travellers from (sub)tropical regions [4]. Because of globalisation in travel and trade and under changing ecological conditions, the geographical distribution of the vector of DENV, has been established in France since 2004 and currently, the mosquito species is endemic in large parts of the country including one area close to the Belgian border [7,8]. The presence of in multiple sites in Europe means that also other diseases can be transmitted. Upon introduction by returning viraemic travellers, European cases of CHIKV, DENV and Zika virus infection have been reported [9,10]. As recently as August 2020, five patients in Vicenza province, MC-Val-Cit-PAB-duocarmycin northern Italy, were confirmed to have MC-Val-Cit-PAB-duocarmycin a DENV infection 2 weeks after a household member infected with DENV returned from West Sumatra [11]. Autochthonous DENV infection was first reported in France in 2010 2010 and has since been reported at an almost yearly basis [12,13]. In 2020, by the end of September, six other autochthonous DENV cases had been reported by French authorities, one in the department Hrault and five in the department Alpes-Maritime [1,14,15]. NIK Our case signalled the first evidence of local DENV activity in Dpartement Var in 2020. In the recent past, between 2010 and 2019, six cases of autochthonous transmission were confirmed in the Dpartment Var [12]. However, our cases do not seem to have any connection with the other autochthonous cases identified in southern France this year. Conclusion The cases reported here again illustrate that travel medicine can have a role as a sentinel for detection of silent circulation of infectious diseases [16]. Clinicians should be aware of the possibility of tropical vector-borne MC-Val-Cit-PAB-duocarmycin diseases acquired by travellers within European areas where competent vectors are present, even when cases have not been reported (yet) by local authorities. Rapid notification by clinicians and communication between national authorities.