Increased number of cases of Chikungunya virus (CHIKV) infection imported from the Caribbean and Central America to northern Italy, 2014

Abstract

This report describes an increased number of cases of Chikungunya virus (CHIKV) infection imported in northern Italy (Emilia-Romagna region) during the period May-September 2014, indicating that the recent spread of CHIKV and its establishment in the Caribbean and in central America, resulted in a high number of imported cases in Europe, thus representing a threat to public health. From May to September 2014, 14 imported cases of CHIKV infection were diagnosed; the patients were returning to Italy from Dominican Republic (n = 6), Haiti (n = 3), Guadeloupe (n = 2), Martinique (n = 1), Puerto Rico (n = 1) and Venezuela (n = 1). Phylogenetic analysis performed on the envelope protein (E1) gene sequences, obtained from plasma samples from two patients, indicated that the virus strain belongs to the Caribbean clade of the Asian genotype currently circulating in the Caribbean and Americas. The rise in the number of imported cases of CHIKV infection should increase healthcare professionals' awareness of the epidemiological situation and clinical presentation of CHIKV infection in order to enhance surveillance and early diagnosis in the forthcoming season of vector activity in Europe and North America.

Keywords: Arbovirus; Chikungunya virus; Italy; epidemiology; phylogeny.

Fig. 1.

Phylogenetic analysis of the envelope E1 gene sequences (1518 nt) from two cases of CHIKV infection. Maximum-likelihood tree was inferred with the GRT + G model with 1000 bootstrap replicates using MEGA 5 software (bootstrap values ⩾80% are shown). CHIKV strains sequenced in this study (GenBank accession nos.: KP252141 and KP252142) are indicated by a black circle (•). The tree was rooted by using the O'nyong-nyong virus as the outgroup virus. Scale bar indicates nucleotide substitution per site.