The New Influenza A Virus: A/Mexico/2009 (H1N1) Practice Point for Caregivers of Children and YouthThe New Influenza A Virus: A/Mexico/2009 (H1N1) Practice Point for Caregivers of Children and YouthInfectious Diseases and Immunization Committee, Canadian Paediatric Society (CPS)
E-publication: May 6, 2009
Paediatr Child Health 2009;14(5):337 [Summary only]
Index of position statements from the Infectious Diseases and Immunization Committee
| The Canadian Paediatric Society gives permission to print single copies of this document from our website. Visit the index of position statements to see which are available as pdf files. For permission to reprint or reproduce multiple copies, please submit a detailed request to info@cps.ca. |
Contents
A new H1N1 influenza A virus of swine origin (A/Mexico/2009 [H1N1]) that causes respiratory disease in humans was first reported in early April 2009. By early May, countries had reported a total of almost 1,000 confirmed cases to the World Health Organization, with the majority reported in Mexico (1). Serious illness and deaths have occurred in children and youth as well as in adults, although to date the vast majority of severe cases have been in Mexico. The purpose of this Paediatric Infectious Disease Note is to provide a brief overview of: 1) the clinical manifestations; 2) the epidemiology; 3) diagnostic tests; 4) treatment; and 5) prevention and control measures for A/Mexico/2009 (H1N1).
CLINICAL MANIFESTATIONSSymptoms of A/Mexico/2009 (H1N1) appear to be similar to those of typical influenza: fever, lethargy, cough and lack of appetite, sometimes accompanied by a runny nose, sore throat, vomiting and diarrhoea. Symptoms vary from mild—cases with cough but no fever—to very severe with viral pneumonia and respiratory failure. Clinicians should consider the possibility of infection with this new influenza virus in patients presenting with influenza-like illness, especially if they have recently returned from an affected areaor have been in close contact with someone suspected of being infected with this virus.
While secondary bacterial infection is a common occurrence among Canadian children ill enough to require hospitalization for typical influenza (2), this was not observed among the 33 cases of serious illness (with 7 deaths) examined to date in Mexico (3). Risk factors for severe disease with this new H1N1 virus are not yet clear. The Mexican pattern with severe illness and deaths occurring in previously healthy young adults differs from typical influenza, where severe disease usually occurs in the very young and very old.
EPIDEMIOLOGYA/Mexico/2009 (H1N1) appears to be spread directly from person to person in the same manner as typical influenza—primarily by droplets or by direct contact with contaminated surfaces. Both influenza A and B viruses can survive for 8 to 12 hours on cloth, paper, and tissues and for up to 2 days on hard, non-porous surfaces such as stainless steel and plastic (4). Touching contaminated surfaces can allow the virus to be transferred to the hand and then to the eyes, nose or mouth and the respiratory tract.
Attack, hospitalization and fatality rates for A/Mexico/2009 (H1N1) are unknown at this time. With a typical influenza outbreak, the annual hospitalization rate in Canada for those between 0 to 19 years of age is about 18 admissions per 100,000 population. But the highest rates occur in infants 6 to 12 months of age: approximately 200/100,000 or equivalent to the rate for adults aged 65 to 69 years (5).
The incubation period of H1N1 is not known, but incubation for influenza during most outbreaks is usually 1 to 4 days with a mean of 2 days. Children and youth remain infectious for 7 days after the onset of illness but infectivity may be longer in some cases. For A/Mexico/2009 (H1N1), self-isolation for those infected (ie, staying home from school or work) is suggested for 7 days—possibly longer if symptoms persist—in order to minimize transmission to others.
DIAGNOSTIC TESTSVerification that an acute respiratory influenza-like illness is due to A/Mexico/2009 (H1N1) requires laboratory confirmation either by isolating the virus in tissue culture or detection by RT-PCR. The most appropriate specimens for testing are nasal-pharyngeal aspirates or swabs (see video for specimen collection technique: http://www.youtube.com/watch?v=TFwSefezIHU). Provincial/territorial public health laboratories can undertake the testing or arrange for testing at the National Microbiology Laboratory in Winnipeg. Serological testing is not yet available and has no value in diagnosing acute cases.
Not all children and youth with respiratory symptoms suggestive of influenza need to be tested. Testing is indicated with serious illness. For children and youth with symptoms and epidemiologic links for possible A/Mexico/2009 (H1N1), local public health authorities may also suggest testing. Some locales have used special off-site testing centres during outbreaks.
TREATMENTChildren and youth who are ill with influenza, including those with A/Mexico/2009 (H1N1), should stay home and away from daycare, school or work, and avoid other people until their symptoms have resolved. If the illness is mild, patients should avoid visiting their physician’s office, walk-in clinic or emergency room unnecessarily, as it may put others at risk. Treatment is symptomatic. Fever may be controlled with acetaminophen or ibuprofen. Aspirin and medications containing salicylates should be avoided because of the potential risk of developing Reye’s syndrome.
As with any influenza-like illness, parents are advised to seek urgent medical care for their child or youth if symptoms progress (see Table 1).
So far, isolates of A/Mexico/2009 (H1N1) have been sensitive to the neuraminidase inhibitors. Zanamivir, an inhaled powder formulation, nd oseltamivir, an oral medication, are available in Canada. Recommendations on dosage of these drugs in children have been published by the Canadian Pharmacists Association (6) and the Centers for Disease Control and Prevention (7) (see Tables 2a and 2b). Oseltamivir recently received emergency approval in the United States for use in infants under one year of age, with suggested dosage guidelines (7). Other influenza viruses have become resistant to these antivirals (9), and their general use for treatment of mild cases is not recommended. In Canada, to maximize the benefit of these antivirals, treatment for A/Mexico/2009 (H1N1) is suggested in two situations only: when children are hospitalized with this strain of influenza, and when outpatient children who are moderately ill also have one of the underlying conditions listed in Table 3.
Neither maternal illness with influenza nor antiviral therapy are contraindications to breastfeeding. (www.cdc.gov/h1n1flu/clinician_pregnant.htm)
PREVENTION AND CONTROLChildren and youth with known exposure to a confirmed case who also have an underlying condition which may predispose them to severe disease (Table 3) should receive prophylaxis. Prophylaxis for healthy children and youth is not indicated.
There is currently no vaccine that covers A/Mexico/2009 (H1N1). Although development is ongoing, it will likely take 6 months or more for a vaccine to become available. A recent review of the 1957 influenza pandemic indicates that accumulated heterosubtypic immunity acquired through past annual immunizations or natural infections may provide some protection during a pandemic strain (10). This suggests that those who have received regular yearly influenza immunizations may have a diminished risk for severe disease.
Personal measures (respiratory hygiene) to minimize transmission include: covering a cough or sneeze using a sleeve or a tissue (see video at www.coughsafe.com/media.html), putting used tissues into a wastebasket, performing hand hygiene (eg, handwashing with non-antimicrobial soap and water or an antiseptic hand sanitizer) after contact with contaminated secretions/objects/materials, and regularly throughout the day.
In ambulatory settings such as a doctor’s office or clinic, standard respiratory hygiene procedures must be followed (11). Signs should be posted at entrances with instructions to tell the receptionist promptly if symptoms of a respiratory infection are present, and to practice proper respiratory hygiene. Ideally, patients with a respiratory illness should be separated from other patients and wear a surgical mask in the waiting room. If masks are not available, or not feasible because of a child’s inability to comply, the child’s nose and mouth should be covered with tissues when coughing or sneezing. Waiting areas should be equipped with conveniently located hand sanitizer dispensers. Where sinks are available, ensure supplies for hand washing (ie., soap, disposable towels) are frequently replenished. After a patient with suspected influenza leaves, surfaces and equipment that the child may have come in contact with need to be cleaned using a germicidal disinfectant (11).
In hospitals, recommendations for infection control procedures for preventing droplet and aerosol transmission of H1N1 infection are evolving and may vary: Local guidelines should be consulted. Additional measures such as the use of N95 masks may be recommended by health authorities for specific procedures or for all direct patient care.
The Public Health Agency of Canada (www.phac-aspc.gc.ca/index-eng.php), the Centers for Disease Control and Prevention (www.cdc.gov) and the World Health Organization (www.who.int/en/) have national and international updates on A/Mexico/2009 (H1N1) as well as guidance as the situation develops. Provincial/territorial public health departments have regional and local guidance and resources. Health care providers need to stay tuned for any changes in the advice if the epidemic changes in severity or in numbers affected.
Posted: May 2009
| Disclaimer: The recommendations in this position statement do not indicate an exclusive course of treatment or procedure to be followed. Variations, taking into account individual circumstances, may be appropriate. Internet addresses are current at time of publication. |
