Roma, 23 dic. (Adnkronos Salute) - Ricercatori brasiliani hanno condotto il primo studio mediante autopsia per esaminare le cause precise di morte nelle vittime della nuova influenza A. Rilevando che in buona parte erano sane. "La mancanza di informazioni precise sulla fisiopatologia di questa nuova malattia è un limite per arrivare a una gestione clinica migliore e un elemento che blocca lo sviluppo di strategie terapeutiche", sottolinea il principale autore dell'indagine, Thais Mauad , del Dipartimento di patologia della São Paulo University. I risultati delle sue osservazioni saranno pubblicate il 1 gennaio sulla rivista 'American Journal of Respiratory and Critical Care Medicine'. I ricercatori hanno esaminato 21 pazienti morti a San Paolo con infezione da virus H1N1 confermata fra luglio e agosto 2009. La maggior parte aveva fra i 30 e i 59 anni. Gli scienziati hanno rilevato che tre quarti del campione (il 76%) aveva malattie preesistenti come problemi cardiovascolari o tumori , ma nel rimanente quarto non sono state osservate condizioni mediche che potessero complicare la situazione. Inoltre, mentre gli studi precedenti avevano mostrato che la maggior parte dei pazienti con infezioni non fatali aveva febbre, tosse e mialgia, Mauad fa notare che "la gran parte dei pazienti con una forma mortale della malattia presentava difficoltà respiratorie, mentre febbre e mialgia erano meno frequenti". Tutti i pazienti sono morti a causa di danni gravi ai polmoni, ma sono stati rilevati tre diversi tipi di problemi, elemento che indica come il virus pandemico uccida in diversi modi: con danni acuti, bronchioliti necrotizzanti o emorragie. Saranno necessari approfondimenti scientifici per capire precisamente come e perché certi pazienti soccombono alla progressione fatale dell'infezione da H1N1, precisano gli esperti. Gli sforzi futuri, dice Maud, "si concentreranno nella comprensione delle risposte immunitarie in caso di infezione grave, che potrebbe portare a nuovi approcci terapeutici".
H1N1, neuraminidasi-inibitori e gravidanza
Il ceppo influenzale H1N1 è suscettibile ad alcuni inibitori delle neuraminidasi, che colpiscono la fase precoce dell'infezione, ma risulta invece resistente a diversi adamantani. E' opinione comune che le donne gravide siano a rischio di complicazioni dell'influenza, soprattutto nel terzo trimestre, e fra queste complicazioni figura la mortalità, anche se i dati in merito sull'influenza suina sono limitati. Sia in queste pazienti che in altri soggetti a rischio di complicazioni, il trattamento con inibitori delle neuraminidasi è consigliato anche a scopo di chemioprofilassi, e deve essere iniziato entro 48 ore dalla comparsa dei sintomi influenzali. Si tratta di farmaci non particolarmente teratogeni nella razza umana, ma la loro sicurezza e metabolizzazione non è uniforme fra i singoli medicinali, e quindi potrebbero sussistere alcune indicazioni preferenziali. Essi comunque non costituiscono controindicazione all'allattamento al seno, che anzi va proseguito per via delle note proprietà anti-infettive del latte umano. Attualmente, come è noto, non è disponibile alcun vaccino contro questo ceppo influenzale: le vaccinazioni stagionali nelle donne gravide comunque andrebbero praticate in ogni caso, per via della possibile sovrapposizione con altri ceppi. E' comunque poco probabile che un futuro vaccino inattivato contro l'influenza suina possa essere controindicato durante la gravidanza o l'allattamento, proprio come accade con i normali vaccini antiinfluenzali. (Can Med Assoc J onljne 2009, pubblicato il 15/6)
All'influenza piace il freddo, scoperto il perché
L'influenza va in 'letargo' con la bella stagione perché non resiste al caldo. Con le alte temperature, in altre parole, il virus si scioglie come fosse neve al sole, o meglio si liquefa il suo mantello protettivo. Per questo, rivela uno studio dei National Institutes of Health statunitensi, che ha guadagnato le pagine della rivista Nature Chemical Biology, d'inverno l'influenza colpisce, mentre d'estate si affretta ad andare in pensione. Gli studiosi Usa, capitanati da Joshua Zimmerberg, hanno scoperto che il virus dell'influenza si protegge con un 'cappotto' di grasso che si scioglie alle alte temperature estive. D'inverno, al contrario, il freddo diventa un prezioso alleato poiché mantiene solido il mantello che salvaguarda il virus. "Come le M&M's", le caramelle al cioccolato prodotte della Mars, "si sciolgono in bocca - spiega Zimmerberg facendo proprio quest'esempio - la cortina di protezione del virus si liquefa solo quando entra nelle vie respiratorie" lasciando qui il virus denudato dal suo 'giubbetto di salvataggio', ma protetto dal calduccio fisiologico del naso e pronto, pertanto, a scatenare l'infezione. D'estate, tuttavia, il mantello si scioglie ancor prima che il virus 'assalti' il malcapitato di turno. Grazie a sofisticate tecniche i virologi Usa hanno stanato e identificato lo strato di grasso che riveste il virus influenzale quando questo 'viaggia' all'esterno, pronto a colpire. Si tratta di uno strato semisolido e gelatinoso che rimane intatto al di sotto di una certa temperatura. Ma se il clima si surriscalda il mantello ha vita breve: il grasso si scioglie e il virus resta scoperto. Affinché l'influenza colpisca è invece necessario che lo strato di grasso venga meno solo una volta giunto nel naso, dove la temperatura è alta. E' nel tratto nasale, infatti, che il virus deve uscire, ovvero abbandonare la cortina di protezione per dare vita all'infezione. Questa scoperta - assicurano i ricercatori - è destinata ad aprire la strada a nuove possibilità per contrastare il virus e controllare meglio le stagioni influenzali.
Progressive ordering with decreasing temperature of the phospholipids of influenza virus. Nat Chem Biol. 2008
Multiple local contact sites are induced by GPI-linked influenza hemagglutinin during hemifusion and flickering pore formation. Traffic. 2000
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Oggetto: CDC Health Advisory - Recommendations for Early Empiric Antiviral Treatment in Persons with Suspected Influenza -10-19-09
Da: "Clinician Outreach and Communication Activity (CDC)" (inserisici in rubrica)
Data: Lun, 19 Ottobre 2009, 5:45 pm
A: CDC-CLINICIANTERRORISMANDEMERGRESPUPDATES@LISTSERV.CDC.GOV
Priorità: Normale
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This is an official
CDC Health Advisory
Distributed via Health Alert Network
October 19, 2009, 13:51 EDT (01:51 PM EDT)
CDCHAN-00299-09-10-19-ADV-N
Recommendations for Early Empiric Antiviral Treatment in Persons with Suspected Influenza who are at Increased Risk of Developing Severe Disease
Summary Recommendations: When treatment of influenza is indicated in a patient with suspected influenza, health care providers should initiate empiric antiviral treatment as soon as possible. Waiting for laboratory confirmation of influenza to begin treatment with antiviral drugs is not necessary. Patients with a negative rapid influenza diagnostic test should be considered for treatment if clinically indicated because a negative rapid influenza test result does not rule out influenza virus infection. The sensitivity of rapid influenza diagnostic tests for 2009 H1N1 virus can range from 10% to 70%, indicating that false negative results occur frequently.
Situation
The 2009 pandemic H1N1 influenza virus continues to be the dominant influenza virus in circulation in the U.S. The benefit of antiviral treatment is greatest when it is initiated as early as possible in the clinical course. Several recent reports have indicated two problems related to antiviral treatment: (1) some patients with suspected influenza who are at higher risk of developing severe complications, including hospitalized patients, were not treated at all with antiviral medications because of a negative rapid influenza diagnostic test result and (2) initiation of treatment was delayed for some patients with suspected influenza who are at higher risk of developing severe complications, including hospitalized patients, because clinicians were waiting for results of real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) assay.
Who is prioritized for treatment with influenza antiviral drugs?
Most healthy persons (i.e., those without a condition which puts them at higher risk for complications) who develop an illness consistent with uncomplicated influenza do not need to be treated with antiviral medications and will recover without complications. However, clinical judgment should be the ultimate guide in making antiviral treatment decisions for ill persons who are not at higher risk for complications from influenza.
Early empiric treatment with oseltamivir or zanamivir is recommended for all persons with suspected or confirmed influenza requiring hospitalization. Prompt empiric outpatient antiviral therapy is also recommended for persons with suspected influenza who have symptoms of lower respiratory tract illness or clinical deterioration regardless of previous health or age.
Early empiric treatment should be considered for persons with suspected or confirmed influenza who are at higher risk for complications, even if not hospitalized, including:
o Children younger than 2 years old
o Adults 65 years and older
o Pregnant women
o Persons with the following conditions:
· Chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, hematological (including sickle cell disease), or metabolic disorders (including diabetes mellitus);
· Disorders that that can compromise respiratory function or the handling of respiratory secretions or that can increase the risk for aspiration (e.g., cognitive dysfunction, spinal cord injuries, seizure disorders, or other neuromuscular disorders)
· Immunosuppression, including that caused by medications or by HIV;
· Persons younger than 19 years of age who are receiving long-term aspirin therapy, because of an increased risk for Reye syndrome.
When should health care providers start treatment with antiviral drugs?
Once the decision to administer antiviral treatment is made, oseltamivir or zanamivir should be initiated as soon as possible. Evidence for benefit from antiviral treatment in studies of seasonal influenza is strongest when treatment is started within 48 hours of illness onset. However, some studies of oseltamivir treatment of hospitalized patients with seasonal influenza have indicated benefit, including reductions in mortality or duration of hospitalization, even for patients whose treatment was started more than 48 hours after illness onset.
When treatment is indicated, health care providers should not wait for laboratory confirmation of influenza to begin oseltamivir or zanamivir treatment of patients with suspected 2009 pandemic H1N1 influenza virus infection. Patients with a negative rapid influenza diagnostic test should be considered for treatment if clinically indicated because a negative result does not rule out influenza virus infection. The sensitivity of rapid influenza diagnostic tests to detect 2009 H1N1 virus in respiratory specimens ranges from 10% to 70%, and therefore false negative results occur frequently. Similarly, false negative results can also occur with immunoflorescence assays.
What actions should health care providers take when waiting for influenza test results
Health care providers should empirically treat persons with suspected influenza illness who are at increased risk for complications if clinically indicated while influenza test results are pending. Antiviral treatment is most effective when administered as early as possible in the course of illness. The rRT-PCR tests are the most sensitive and specific influenza diagnostic tests, but they may not be readily available, obtaining test results may take one to several days, and test performance depends on the individual rRT-PCR assay. Antiviral treatment should not be delayed until rRT-PCR test results are available.
For More Information
Updated Interim Recommendations for the Use of Antiviral Medications in the Treatment and Prevention of Influenza for the 2009-2010 Season: http://www.cdc.gov/H1N1flu/recommendations.htm
Interim Recommendations for Clinical Use of Influenza Diagnostic Tests During the 2009-10 Influenza Season: http://www.cdc.gov/h1n1flu/guidance/diagnostic_tests.htm
Questions & Answers:
Antiviral Drugs, 2009-2010 Flu Season:http://www.cdc.gov/h1n1flu/antiviral.htm
Influenza Diagnostic Testing: http://www.cdc.gov/h1n1flu/diagnostic_testing_clinicians_qa.htm
Updated Interim Recommendations for Obstetric Health Care Providers Related to Use of Antiviral Medications in the Treatment and Prevention of Influenza for the 2009-2010 Season: http://www.cdc.gov/H1N1flu/pregnancy/antiviral_messages.htm
Antiviral Drugs: Summary of Side Effects: http://www.cdc.gov/flu/protect/antiviral/sideeffects.htm
General information for the public on antiviral drugs is available in “2009 H1N1 and Seasonal Flu: What You Should Know About Flu Antiviral Drugs” at http://www.cdc.gov/H1N1flu/antivirals/geninfo.htm .
Downloadable brochures and informational flyers, including one on antiviral drugs, are available at http://www.cdc.gov/h1n1flu/flyers.htm .
For the FDA page on antiviral influenza drugs:
http://www.fda.gov/Drugs/DrugSafety/InformationbyDrugClass/ucm100228.htm
For additional information, you can also call CDC’s toll-free hotline, 800-CDC-INFO (800-232-4636) TTY: (888) 232-6348, which is available 24 hours a day, every day.
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J Med Virol. 2011 Jun 2. doi: 10.1002/jmv.22113. [Epub ahead of print]
Nationwide surveillance of 18 respiratory viruses in patients with influenza-like illnesses: A pilot feasibility study in the French Sentinel Network. 2011
Falchi A, Turbelin C, Andreoletti L, Arena C, Blanchon T, Bonmarin I, Hanslik T, Leruez-Ville M, De Lamballerie X, Carrat F.
Source
INSERM, UMR-S 707, Paris, France; UPMC Université Paris 06, UMR-S U707, Paris, France. falchi@u707.jussieu.fr.
Abstract
The aim of the present study was to test the feasibility of integrating the diagnosis of 18 respiratory viruses into clinical surveillance of influenza-like illness using a PCR-DNA microarray detection assay. The study took place in the French Sentinel Network, a nationwide surveillance network of General Practitioners (GPs) representative of French GPs in terms age, location, and type of practice (urban/rural). Three virological laboratories also participated in the study. The study was planned for 5 weeks from January 25, 2010 to February 27, 2010. A subset of 150 Sentinel GPs, located in mainland France, was enrolled to collect clinical data and nasopharyngeal samples from every first patient of the week having a medical visit for influenza-like illness defined as a sudden fever of 39°C or more with respiratory symptoms and myalgia. Sixty-three GPs (42%) collected 103 samples while 87 GPs (58%) did not. GPs did not differ with respect to their age, gender, urban/rural distribution, or years of inscription in the Sentinel Network. Patients included were of a similar age and had similar vaccination characteristics, but were more frequently men than influenza-like illness patients reported to the network during the study period. Sixty-one viruses were detected from 56 of 96 (58%) interpretable samples. The respiratory viruses detected most frequently were metapneumovirus and respiratory syncytial virus. This study showed that virological diagnosis of 18 respiratory viruses can be combined with surveillance of clinical influenza-like illness in general practice. Although feasibility has not been demonstrated yet, it will be evaluated over the winter of 2010-2011. J. Med. Virol. © 2011 Wiley-Liss, Inc.
