A confirmed case of novel influenza A (H1N1) virus infection is defined as a person with an influenza-like illness with laboratory confirmed novel influenza A (H1N1) virus infection by one or more of the following tests:

• real-time RT-PCR
• viral culture

Medical care for patients with novel influenza A (H1N1) virus

Not all patients with suspected novel influenza (H1N1) infection need to be seen by a health care provider.For most people, the illness appears to be mild and self-limiting. Cases have been confirmed in all age groups, but children and younger people seem to be much more likely to be affected, whereas fewer cases have been confirmed to date in older adults.

For a minority of people, influenza A(H1N1) has caused severe illness with complications. In many, but not all, of these cases underlying risk factors (co-morbidities # ) have been identified that are likely to have contributed to the severity of the condition.

Complications of Influenza:

The following are the recognized complications of influenza. At times these complications, such as an exacerbation of chronic airways disease, may be the presenting symptom. Respiratory complications are the most common ones (especially secondary infections). Cardiac events following influenza are not uncommon.

# Co-morbidities / Risk factors:

Patients who are considered vulnerable to severe outcomes and should be a focus of early identification, assessment and treatment, include the following:

• Chronic respiratory conditions, including asthma, COPD, Obstructive sleep apnoea
• Pregnant women, esp. in second or third trimester
• Morbid obesity
• Other possible predisposing conditions, such as chronic cardiac disease (not simple hypertension), and chronic illnesses including diabetes mellitus, renal failure, haemoglobinopathies, immunosuppression (including cancer, HIV/AIDS, chemotherapy, long term steroids).
• Adults > 65 years of age esp. those with other chronic diseases
• Children under the age of 5 years, esp. those below the age of 2 years

As more epidemiologic and clinical data become available, these risk groups might be revised.

Patient Home Assessment Tool

The following patient home assessment tool designed to detect moderate or severe influenza can be used to guide the patient on the need to seek professional medical attention.

Patients with ILI are advised to seek medical care should they develop any of the symptoms and signs listed as below:

Patients to be tested for novel influenza A / H1N1 virus

* Influenza-like-illness (ILI) is defined as fever (esp. temperature > 38°C) and a cough and/or a sore throat in the absence of a KNOWN cause other than influenza.

Patients with mild clinical disease should not be tested as a routine

To test for novel H1N1 influenza virus, upper respiratory specimens, such as a nasopharyngeal swab, throat swab, or tracheal aspirate should be collected.

** Clinical assessment tool for moderate to severe influenza:

Patients to be hospitalized for novel influenza A / H1N1 virus

Patients with suspected influenza manifesting with mild disease will not require admission to hospital.

Patients should be clinically assessed and the admission decision will be based mainly on the severity of the illness.

Antiviral Treatment for Novel Influenza A / H1N1

Clinical judgment is an important factor in treatment decisions.

Persons with suspected novel H1N1 influenza who present with an uncomplicated febrile illness (mild disease) typically do not require treatment.

If a patient is not in a high-risk group or is not hospitalized, they generally do not require antiviral therapy. Nonetheless, healthcare providers should use clinical judgment to guide treatment decisions esp. in cases where there has been rapid deterioration in clinical status..

Many patients who have had novel influenza (H1N1) virus infection, but who are not in a high-risk group have had a self-limited respiratory illness similar to typical seasonal influenza. For most of these patients, the benefits of using antivirals may be modest at best. Therefore, testing and treatment efforts should be directed primarily at persons who are hospitalized or at higher risk for influenza complications.

Once the decision to administer antiviral treatment is made, treatment with oseltamivir or zanamivir should be initiated as soon as possible after the onset of symptoms. Evidence for benefits 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 > 48 hours after illness onset. Recommended duration of treatment is 5 days. Antiviral doses recommended for treatment of novel H1N1 influenza virus infection in adults or children 1 year of age or older are the same as those recommended for seasonal influenza.

Oseltamivir

Adults and adolescents: The recommended oral dose of oseltamivir capsules in adults and adolescents 12 years of age and older is 75 mg bd for 5 days. Adults and adolescents 12 years of age and older who are unable to swallow capsules may receive the appropriate dose of oseltamivir suspension. Severe cases e.g. in patients requiring ICU care, a higher dose of 150mg bd may be appropriate.

Paediatric patients: The recommended oral dose of oseltamivir for paediatric patients 1 year and older who cannot swallow a 75 mg capsule is shown below.

Zanamivir

The recommended dose of zanamivir is 2 puffs (2 x 5 mg) bd for 5 days providing a total daily inhaled dose of 20 mg.

Antiviral Chemoprophylaxis for Novel Influenza A / H1N1

For antiviral chemoprophylaxis of novel (H1N1) influenza virus infection, either oseltamivir or zanamivir are recommended. Duration of antiviral chemoprophylaxis post-exposure is 10 days after the last known exposure to novel (H1N1) influenza. The indication for post-exposure chemoprophylaxis is based upon close contact with a person who is a confirmed case of novel influenza A (H1N1) virus infection during the infectious period of the case. The infectious period is defined as one day before until 7 days after the case’s onset of illness. If the contact occurred with a case whose illness started more than 7 days before contact with the person under consideration for antivirals, then chemoprophylaxis is not necessary.

Close Contacts are defined either:

• as those who live in the same house / premises (household contacts)
• those who have sustained close contact (< 3feet) for at least 4 hours

Dosage of antiviral prophylaxis is as follows:

• Oseltamivir 75 mg daily for 10 days
• Zanamivir 10 mg (2 puffs) daily for 10 days

Algorithm for H1N1 management

• * Home Care: supportive care including adequate fluids, paracetamol, cough mixtures, lozenges, etc.
• @ See Patient Home Assessment Tool
• Antiviral therapy is best given within first 48 hours of illness. Beyond 48 hours, antiviral medication may still be indicated on clinical grounds (eg. Progressive symptoms)
• If empirical treatment with antivirals has been given, treatment should cease if the swab result is negative for H1N1.