venerdì 28 marzo 2008

H5N1 e H3N2: dimostrato un caso di co-infezione

Uno studio presentato durante la recente Conferenza Internazionale sulle Malattie Infettive Emergenti ha confermato per la prima volta un caso di co-infezione da virus influenzali umani e aviari in una ragazzina indonesiana (Avian, human flu coinfection reported in Indonesian teen): sebbene alcuni ricercatori abbiano sollevato dubbi sul caso, lo studio ha rivelato la presenza di materiale genetico del virus umano A/H3N2 e di quello aviario A/H5N1; la presentazione clinica era tipica dell'influenza stagionale, con sintomi a carico della alte vie respiratorie ma torace negativo per la polmonite; nessun sintomo neurologico o gastrointestinale (tipici dell'H5N1).
Di seguito riportiamo l'abstract dello studio per chi fosse interessato allìapprofondimento.

Case report: Dual infection of H5N1 avian influenza and H3N2 human influenza in Jakarta Indonesia, April 2007
V. Setiawaty, K. N. A Pangesti, H. A. Prawestri, D. H. Mulyono, E. Burhan, Priyanti, E. R. Sedyaningsih.

Human influenza A viruses are transmitted year round in Indonesia with a higher frequency
detected among patients with influenza-like illness during the rainy season. In 2005, the Ministry of Health established a referral system for patients with avian Influenza A virus (H5N1) infection and identified 113 patients with laboratory-confirmed disease between 2005 and 2007. We are reporting a case-report of a patient with simultaneous infection with avian (H5N1) and human influenza A (H3N2) virus infection.

In April 2007, a 16 year old female patient was hospitalized with respiratory illness at a referral hospital in Jakarta. A case investigation form was used to collect clinical and epidemiologic data and clinical samples were collected for hematological profile and as well as acute and convalescent antibody titers for H1, H3, and H5 antigen using HAI assays. Throat & nasal swab specimens were collected on the 6th day of onset, when she visited NIHRD laboratory and tested with real-time and gel-based RT-PCR for H1, H3 and H5 at NIHRD-MOH. Patient was hospitalized after results showed H5N1 positive infection. Specimens were sent to the Eijkman Institute for confirmation of PCR results and genetic sequence analysis.
The patient presented with moderate symptoms of fever > 38°C, sore throat, cough, rhinitis, headache and myalgia, but no dyspnoea. The thrombocyte counts were 250,000 - 269,000 cells/mm3, leucocytes 4,700–5,800 cells/mm3, lymphocyte 31 – 44.7%. X ray and CT scan of thorax showed no pneumonia. PCR results were positive from throat and nasal swabs for influenza A (H3N2) and influenza A (H5N1) by real-time and gel based
RT-PCR. These results were confirmed by repeat testing at Eijkman. HAI antibody titers were negative for H3N2 and 1:10 for H5N1 from sera that was collected 6 days after onset of illness. HAI antibody titers from convalescence sera were 1:640 for H3N2 and negative for H5N1.

This is the first case-report of a human with both influenza A (H5N1) and influenza A (H3N2) co-infection. Such infections are of great concern due to the possibility of genetic reassortment leading to the emergence of a H5N1 strain that is more easily transmitted human to human and emphasizes the importance of advanced laboratory-based surveillance in geographic regions where both human and avian influenza viruses are co-circulating.

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