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A new A(H1N1) influenza virus was detected in April 2009. The virus is now causing a pandemic of influenza. The article presents an overview of symptoms, complications, vulnerable groups, diagnosis and treatment.The overview is based on literature identified through a search in PubMed (using PubMed's own search strategy) and on official reports from WHO and the disease control centres of EU and the USA.The new influenza A(H1N1) has so far mainly affected young people, only few people over 60 years. The clinical presentation is similar to that of ordinary influenza; but nausea, vomiting and diarrhoea seem to be more common. The reported risk of complications and case fatality are low, but hospitalisation, pneumonia and deaths have occurred, also in previously healthy young individuals. Antiviral treatment with oseltamivir or zanamivir is likely to be as effective as in ordinary influenza.Mild cases may be underrepresented in the published literature. It is important to keep up-to-date on international reports on the nature of the disease in order to best prepare clinicians to diagnose and treat patients when the epidemic hits Norway with full force.

Influenza virus infection can be prevented and treated with antiviral drugs. The usage of such drugs in Norway has been infrequent, however, they are an important component in our pandemic preparedness planning, as it will probably be difficult to get access to the appropriate vaccine in time before the pandemic reaches the country. The first generation of influenza drugs acquired resistance to a large degree, in contrast to the modern neuraminidase inhibitors that until recently have had minor problems with resistance.This review is based on research found in relevant published literature, together with experience from a virology reference laboratory and participation in a national and international surveillance including susceptibility testing.While resistance has been a longstanding problem with the use of the "old" influenza drugs amantadine and rimantadine, only during the winter 2007/2008 did it become clear, that a certain type of virus acquired widespread resistance against the neuraminidase inhibitor oseltamivir. Resistance surveillance is crucial for the correct choice of empiric treatment for influenza infection, and will be one of the most important tasks at the National Influenza Centre in certain phases of a pandemic. The current situation with an increasing resistance problem strengthens the need to conduct continuous monitoring of antiviral susceptibility, as well as development of new antiviral drugs and treatment regimes.

More and more viral infections are treated with antiviral drugs, and resistance against these drugs is steadily increasing. Our aim is to give a general understanding of viral resistance and its clinical significance.This article is based on review of published literature on the subject, international recommendations and our own experience as a national reference laboratory for hepatitis viruses.Development of viral resistance is an increasing problem with long-term treatment of both latent and chronic viral infections and may be one of the reasons for clinical treatment failure. Susceptibility testing is therefore an important diagnostic tool in cases of suspected failure during antiviral treatment, and is also necessary for customising of treatment to each individual patient. In Norway, susceptibility testing is offered for HIV, HBV, CMV and influenza, whereas systematic surveillance for the time being is only performed on HIV and influenza resistance. Surveillance on viral resistance is necessary in order to choose the adequate empirical therapy and to monitor the spread of resistant virus in the population. Prevalence of resistance can be limited with infection control measures and appropriate antiviral treatment, especially used in combinations of effective drugs directed at different enzymes and proteins within the virus.

The incidence of whooping cough has increased in recent years in Norway, especially amongst older children and adults; in 2004 it was 168/100,000.This article is based on our own experience and a review of available literature, identified on Medline with the search word "pertussis".Whooping cough, a disease caused by the bacterium Bordetella pertussis, is transmitted via respiratory droplets. Sources of infection for infants are often their parents and siblings. Older children and adolescents contract whooping cough mostly in school, whereas adults usually get the disease from children or colleagues. The typical symptoms are bouts of violent coughing with the classic whoop and post-tussive vomiting. A milder clinical picture can be seen in vaccinated persons, reinfected patients, and in persons above the age of 15. Infants are most at risk of developing serious disease and have the highest numbers of hospitalizations, complications and mortality. But complications are also seen in adolescents and adults, including urinary incontinence, rib fractures and pneumonia. The diagnosis is made by culture or PCR in nasopharyngeal secretions, as well as by detection of antibodies to B. pertussis in serum. If treatment is indicated, macrolides are the drugs of choice; these shorten the duration of symptoms and the period of contagiousness if given in the early stages of the disease. To help combat whooping cough in Norway, from 2006 an extra vaccine booster dose will be given to children at the age of seven.