OCTOBER 1, 2009 • WWW.INTERNALMEDICINENEWS.COM INFECTIOUS DISEASES 13 THE EFFECTIVE PHYSICIAN H1N1 Viral Shedding 2009 H1N1 and Antivirals Can Last Past 1 Week BY WILLIAM E. GOLDEN, M.D., AND ROBERT H. HOPKINS, M.D. Background plications from influenza, and one study esti- The 2009 pandemic influenza A(H1N1) virus mates a fourfold increased risk for hospital- BY MITCHEL L. ZOLER 8 days after their symptom onset. (also known as swine flu) was the cause of ization in these patients with 2009 H1N1 in- In contrast, all patients with sea- 98% of influenza cases in the United States fluenza. Oseltamivir and zanamivir are listed ome patients with 2009 pan- sonal flu are routinely culture this summer. Most people infected with this as pregnancy category “C” drugs; however, demic influenza A(H1N1) negative a week after symptom virus have a self-limited illness, but others re- current data recommend oseltamivir for treat- Sshed live virus a few days onset. “We can say that H1N1 ap- quire treatment to achieve recovery. To help ment of suspected or confirmed pandemic longer than commonly occurs pears to be shed longer [than sea- providers appropriately manage this illness H1N1 influenza. The choice of oseltamivir or with seasonal flu, according to a sonal flu] but not much longer,” with antiviral medications, the World Health zanamivir for chemoprophylaxis is not clear. Canadian study with 100 patients. said Dr. De Serres, who also is Organization and the Centers for Disease Patients not at increased risk of complica- The public health implications professor of epidemiology at Control and Prevention released interim guid- tions whose illness is not severe do not rou- of the finding aren’t clear, Dr. Laval University, Quebec. All 43 ance in late August and early September 2009. tinely require antiviral treatment; however, Gaston De Serres said during a H1N1 patients in the study were those who have symptoms of lower respira- press briefing at the annual meet- culture negative 10 days after Conclusions tory tract illness, dyspnea, hypoxemia, ing of the Interscience Confer- symptom onset. Based on current global data, 2009 H1N1 will tachypnea, or other warning symptoms of se- ence on Antimicrobial Agents Another 57 family members of likely be the most common influenza virus vere illness should be treated promptly with and Chemotherapy. these cases had concurrent flulike circulating during this flu season, especially antivirals. All persons with suspected in- The results show that it’s not symptoms, but all 57 were culture among younger patients. fluenza should be counseled on the warning enough to isolate people infected negative the first time they were Approximately 60% of children and 80% signs for severe or lower respiratory illness with pandemic H1N1 flu for just tested. Adding these 57 to the of adults hospitalized with 2009 H1N1 flu and informed of the need for treatment a couple of days after they be- first 43 produced a total of 100 pa- have a comorbid condition known to in- should these develop. come sick or until their fever re- tients apparently infected with crease the risk for severe influenza and/or its The evidence for effectiveness of the in- solves. People “may be tempted H1N1, of whom 8 were culture complications. As in seasonal influenza, the fluenza antivirals is based on data in uncom- to reduce their time at home positive a week after their illness conditions that increase the risk of compli- plicated seasonal influenza and is strongest [when infected by H1N1], but began, establishing a minimum cations with this virus are age under 5 years for treatment begun within 48 hours of the our results show that would not 8% rate for the persistence of or over 65 years, pregnancy, immunosup- onset of illness. be wise,” said Dr. De Serres, a H1N1 shedding beyond 1 week. pression, and chronic heart (excluding hy- The recommended duration of treatment medical epidemiologist at the Dr. De Serres cautioned that pertension), lung, kidney, liver, neurologic, with influenza antivirals is 5 days, although National Public Health Institute the findings don’t mean that all metabolic, or muscular disease. Chronic as- hospitalized patients with severe infections of Quebec. eight patients remained conta- pirin treatment in patients aged 19 years or may benefit from more prolonged treatment The study focused on 43 pa- gious at day 8. Contagion re- less is also a risk factor. and/or higher doses. tients with symptomatic flu who quires more than just shedding People aged 65 or older have a lower risk Antiviral chemoprophylaxis should be re- were culture positive for the pan- live virus; it also requires trans- of infection with the 2009 H1N1 virus than served for persons at increased risk of flu-re- demic virus. In this group, eight mission of an adequate virus do younger people. Pandemic H1N1 appears lated complications who have close contact (19%) remained culture positive dose. ■ to be transmitted like other influenza virus- with someone likely infected with influenza. es; respiratory secretions and bodily fluids of Patients receiving antiviral treatment infected persons should thus be considered should be advised that they remain poten- potentially infectious. tially infectious to others for up to 4 days af- Triple Antiviral Shows Preliminary data suggest that obese and ter the start of therapy. Frequent hand wash- morbidly obese people may be at increased ing and good respiratory hygiene remain risk of hospitalization and death caused by vital adjuncts to treatment. Synergy Against H1N1 2009 H1N1 influenza, but it is uncertain Continued surveillance is important to in- whether this is due to obesity alone or in as- form clinicians and public health authorities BY MITCHEL L. ZOLER versity of Alabama, Birmingham. sociation with other complications. regarding influenza prevalence, strains in The three-drug combination, The current circulating H1N1 influenza communities, and changes in antiviral resis- triple antiviral-drug regimen called Triple Combination An- viruses have continued susceptibility to os- tance patterns. Current influenza surveil- Amay be more effective than tiviral Drug (TCAD) therapy, is eltamivir and zanamivir but are resistant to lance data in the United States is updated any single drug alone against 2009 being developed by Adamas us- amantidine and rimantidine. It is important weekly at www.cdc.gov/flu. pandemic influenza A(H1N1) as ing proprietary formulations and to note that oseltamivir resistance in season- well as seasonal flu strains, based dosages, Dr. Patick said. al H1N1 influenza is common, and that an- References on results from preclinical, tis- Adamas had begun developing tiviral recommendations may change over CDC H1N1 resources can be found at sue-culture studies. TCAD for treating influenza in- the course of this flu season. www.cdc.gov/h1n1flu/guidance. The WHO A clinical trial has launched to fections before the current H1N1 recommendations are at www.who.int/csr/ assess the safety and efficacy pandemic began, and the compa- Implementation disease/swineflu/notes/h1n1_use_ against all influenza type A in- ny says it believes the triple-drug Antiviral treatment decisions should be based antivirals_20090820/en/print.html. fections of a specific combination combination will also be effec- on the clinical suspicion of influenza, the de- of oseltamivir, amantadine, and tive against seasonal strains of in- gree of illness, and the risk of complications. ribavirin, Amy Patick, Ph.D., said fluenza A. Patients infected with The sensitivity of rapid tests ranges from 10% during a press briefing at the an- any type of flu A infection will be to 70%, and withholding therapy while await- nual meeting of the Interscience enrolled in the two clinical stud- ing results can result in delayed treatment or Conference on Antimicrobial ies, Dr. Patick said in an interview. missed opportunities to treat based on false- Agents and Chemotherapy. One study already underway in negative results. Real-time polymerase chain The tissue culture results sug- the Southern Hemisphere will reaction testing, which has significantly bet- gest a synergistic antiviral inter- enroll 250 immunocompromised ter sensitivity and specificity, should be used action among the three agents patients, and will compare the ef- only in patients with suspected influenza that gives them an efficacy 5- to ficacy and safety of TCAD who require hospitalization. 20-fold higher than any of the against monotherapy with os- Antiviral treatment with oseltamivir or three drugs alone or any combi- eltamivir (Tamiflu). A second zanamivir should be initiated as early as pos- DR. GOLDEN (left) is professor of medicine and nation of two of the drugs, said study that is planned to start soon sible in the course of illness for all patients public health and DR. HOPKINS is program direc- Dr. Patick, vice president for re- in the United States, Canada, and with suspected or confirmed influenza who tor for the internal medicine/pediatrics combined search at Adamas Pharmaceuti- Europe will also examine the ef- require hospital admission, and in those who residency program at the University of Arkansas, cals Inc., in Emeryville, Calif. The ficacy and safety of TCAD in are at high risk for complications. Little Rock. Write to Dr. Golden and Dr. Hopkins results were reported at the meet- both immunocompromised and Pregnant women are at high risk of com- at our editorial offices or [email protected]. ing by Mark Prichard, Ph.D., a immunocompetent patients in- professor of pediatrics at the Uni- fected with influenza A. ■