Imported Dengue Virus Serotype 3 | CDC EID

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Volume 17, Number 5–May 2011
Letter
Imported Dengue Virus Serotype 3, Yemen to Italy, 2010
Paolo Ravanini, Eili Huhtamo, Essi Hasu, Felicita Rosa, Stefano Costantino, Maria G. Crobu, Valentina Ilaria, Anna M. Nicosia, Pietro L. Garavelli, and Olli Vapalahti
Author affiliations: Azienda Ospedaliero-Universitaria Maggiore della Carità, Novara, Italy (P. Ravanini, F. Rosa, S. Costantino, M.G. Crobu, V. Ilaria, A.M. Nicosia, P.L. Garavelli); and University of Helsinki, Helsinki, Finland (E. Huhtamo, E. Hasu, O. Vapalahti)

Suggested citation for this article

To the Editor: Dengue is a mosquito-transmitted viral disease endemic to the tropics and subtropics worldwide. It is caused by 4 dengue virus serotypes (DENV-1–4) that belong to the genus Flavivirus. The disease varies from dengue fever to life-threatening hemorrhagic fever and shock that are associated with secondary infections. During recent decades, dengue incidence and prevalence have increased in disease-endemic areas, and the disease has been increasingly recognized in travelers (1). We report a case of dengue in a man who had traveled to Yemen.

In June 2010, a 38-year-old Italian man was admitted to the hospital for high fever (maximum 39.5°C) after a 1-week work-related stay in Yemen, near Mukalla, in the province of Hadhramaut. The patient had visited the countryside where he was heavily bitten by mosquitoes.

On the third day after onset of fever, the patient started to experience strong and unremitting frontal and retro-orbital headache and joint pains, which lasted for 5 days. He also experienced vomiting. Laboratory test results showed mild leukopenia (2.41 × 103 cells/mm3) and lowered platelet counts (96 × 103 cells/mm3), increased liver alanine aminotransferase levels (151 U/L), and mildly abnormal blood clotting (prothrombin time, international normalized ratio 1.24). In 1 week, the patient started to recover and was discharged from the hospital. The patient received antimicrobial (levoxacin) and antipyretic (acetaminophen) drugs. Laboratory testing after discharge showed increased levels of hepatic enzymes, which reached maximum levels on day 13 after onset of symptoms (alanine aminotransferase 669 U/L) and decreased to within reference limits in 1 month.

A plasma sample taken on day 6 after disease onset was positive for flavivirus RNA by reverse transcription–PCR (RT-PCR) specific for members of the genus Flavivirus (2). The RT-PCR product was sequenced, and according to BLAST (www.ncbi.nlm.nih.gov/blast), the 184-bp sequence obtained shared 99% nt identity with dengue serotype 3 viruses in GenBank. The plasma sample also had positive results for dengue virus nonstructural protein 1 (NS1) antigen test (Platelia NS1 Ag ELISA; Bio-Rad, Marnes-la-Coquette, France), anti-dengue immunoglobulin (Ig) M ELISA (Focus Technologies, Cypress, CA, USA), and in an in-house IgG immunofluorescence assay that used DENV-3–infected Vero E6 cells as antigens (titer 40). Other concomitant infections were ruled out by bacterial cultures and by laboratory tests for various viral, bacterial, and parasitic pathogens.

Virus isolation was conducted as described (3). Viral RNA was extracted from the supernatant of the infected Vero E6 cells, and the envelope gene was amplified in an RT-PCR. The amplified product was directly sequenced (details available from P.R. upon request). The obtained envelope gene sequence (GenBank accession no. HQ336219) of 1,479 bp was aligned with 26 other DENV-3 strains, including the most similar sequences identified in nucleotide BLAST search and a global set of sequences representing different genotypes (4), by using MUSCLE (www.ebi.ac.uk/Tools/muscle/index.html). A neighbor-joining phylogenetic tree was inferred by using p-distance, with 1,000 bootstrap replicates in MEGA version 4 (www.megasoftware.net).

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Imported Dengue Virus Serotype 3 | CDC EID


Suggested Citation for this Article
Ravanini P, Huhtamo E, Hasu E, Rosa F, Costantino S, Crobu MG, et al. Imported dengue virus serotype 3, Yemen to Italy, 2010 [letter]. Emerg Infect Dis [serial on the Internet]. 2011 May [date cited].
http://www.cdc.gov/EID/content/17/5/929.htm

DOI: 10.3201/eid1705.101626


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Paolo Ravanini, AOU Maggiore della Carità–Laboratorio di Virologia Molecolare, Via Cottolengo, 2 Galliate 28069, Italy; email: paolo.ravanini@gmail.com