pandemic influenza
 

SWINE INFLUENZA

Influenza (“flu”) is a respiratory illness that can be transmitted from person to person. Flu viruses are of two main genetic types: Influenza A and B. Influenza A strains are further identified by two important surface proteins that are responsible for virulence: hemagglutinin (H) and neuraminidase (N).

Swine flu occurs naturally and may cause outbreaks among wild and domestic swine. People do not normally get swine flu, but each year CDC identifies a few isolated cases of human flu that are caused by flu strains typically associated with swine.

What is swine influenza?
Swine influenza is a respiratory disease of pigs caused by type A influenza viruses. In affected pigs, it causes cough, fever, nasal discharge, lethargy and difficulty breathing. Influenza A viruses are classified by two components of the viral surface, hemagglutinin (H) and neuraminidase (N). Different types of influenza A viruses are infectious to avian and mammalian species. Pigs and people are susceptible to influenza A viruses from both avian and mammalian sources. Infection with multiple viruses can lead to the creation of new “reassorted” viruses with components of pig, bird and human flu origin. Classical swine flu (H1N1) was first isolated in 1930, and many other subtypes have since been identified (e.g. H3N2, H1N2). In the United States, swine influenza outbreaks are most common in fall and winter. In Minnesota, we see peaks of swine flu activity in April through May and September through November.

Avian flu (“bird flu”) is caused by viruses that occur naturally among wild birds, and that may also affect domestic poultry. In 1997 a new H5N1 strain of avian flu emerged in Asia, and has since caused millions of deaths among domestic poultry, and hundreds of deaths in humans. Health officials have been concerned that this strain could cause a human pandemic, and governments around the world have carried out a number of preparedness activities, including vaccine development and stockpiling, and planning for continuity of services.

Pandemic flu is caused when a novel strain of human flu (i.e., one that spreads from person to person) emerges and causes a global outbreak, or pandemic, of serious illness. Because there is little natural immunity, the disease is often more severe than is typical of seasonal flu.

Influenza is an infectious disease caused by the influenza virus. The disease is commonly called flu or grippe. The word influenza is sometimes used to refer generally to either influenza or similar illnesses. The symptoms of influenza include chills, fever, headache, aches, and weakness. The symptoms usually disappear in about a week. The patient's resistance may be lowered, so that secondary infections, such as bacterial pneumonia, follow the influenza.

How influenza spreads. Influenza is mainly a respiratory disease. The virus is inhaled and comes in contact with cells of the upper air passages. It penetrates the cells that line these passages and reproduces within them. In time, new influenza viruses are released from the infected cells and infect other cells along the respiratory tract. Influenza may spread deep within the lungs. The virus may also be carried away in exhaled air and infect other people.

One of the worst global epidemics of influenza occurred in 1918-1919. About 20 million people, including more than 500,000 Americans, died in this epidemic. In 1957-1958, Asian flu caused a worldwide epidemic, as did Hong Kong flu in 1968-1969. Far fewer deaths resulted from these epidemics, due largely to the control of secondary infections with antibiotics.

 




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Step-by-step guide for specimen collection, storage and transportation

1. Put on appropriate personal protective equipment including a mask (N95 mask if available) and surgical gloves (specimen collection poses a risk of aerosol production)

2. Swab each nostril with one swab. Swab the throat using a second swab. (Use only Dacron or Rayon swabs. Wooden swabs are not suitable for testing).

3. Place both swabs together into a container of viral transport medium (VTM).

4. Wrap the container (containing VTM and swabs) in absorbent material (e.g. cotton wool).

5. Place in a secondary container (preferably sturdy plastic or stainless steel) with a well fitting lid. 6. Wrap again in absorbent material and place in a third container (e.g. a cooler box) containing ice (specimens and VTM must be transported at 40C).

7. Put the patient details on the OUTSIDE of this container including:
• Patient Name,
• Health facility (where appropriate),
• Doctor and contact numbers,
• Lab name and contact person, and
• Attach a copy of any investigation forms / specimen slips that have been completed.

8. Transport specimens directly to appropriate laboratory for patients seen at your health facility.


Additional information about specimen collection

• Specimens for virus isolation or for detection of viral nucleic acids or antigens should be taken preferably during the first three days after onset of clinical symptoms, but may be taken up to a week after onset, or even later in severely ill or immunocompromised patients or children under 12 years of age.

• Specimens should preferably be taken prior to commencement of antivirals.

• Nasopharyngeal swabs may be collected instead of nose and throat swabs. Swabs pose a lower risk of infection for staff than do nasopharyngeal aspirates (NPA) or nasal washes, both of which may generate aerosols.

• In addition to swabs from the upper respiratory tract, invasive procedures such as bronchoalveolar lavage or lung biopsy can be performed for the diagnosis of virus infections of the lower respiratory tract where clinically indicated.

• Post mortem samples may also be submitted.

 

Swabs and Viral transport medium (VTM)

• Wooden swabs are not suitable for respiratory virus PCR. Please use Dacron or Rayon swabs.

• All specimens must be transported in viral transport medium (VTM) as instructed above.

• The appropriate swabs and viral transport medium may be obtained from your usual local laboratory. Public sector health practitioners should contact their local NHLS laboratory. Private sector practitioners should contact their usual private laboratory.

• Local laboratories should stock VTM and the appropriate swabs, which may be obtained through your usual supplier. For further information on VTM and swabs contact the National Influenza Centre (Amelia Buys/Cardia Fourie, 011 386 6373).

 

Individuals at high risk for serious complications of influenza

1. Persons (adults or children) with underlying medical conditions and who are receiving regular medical care for conditions such as chronic pulmonary disease (including asthma) and cardiac disease (excluding hypertension), chronic renal and hepatic diseases, diabetes mellitus and similar metabolic disorders

2. Individuals who are immunosuppressed (including HIV infected persons and persons on immunosuppressive medications);

3. Adults and children who have any condition (e.g., cognitive dysfunction, spinal cord injuries, seizure disorders, or other neuromuscular disorders) that can compromise respiratory function or the handling of respiratory secretions or that can increase the risk for aspiration;

4. All persons over the age of 65 years;

5. Children and adolescents who are receiving long-term aspirin therapy and who might be at risk for experiencing Reye’s syndrome after influenza virus infection;

6. Residents of nursing homes and other chronic-care facilities

7. Pregnant women

 

Source :
The National Institute for Communicable Diseases (NICD) of the National Health Laboratory Service (NHLS) In collaboration with: The South African National Department of Health and World Health Organisation (WHO).

SWINE INFLUENZA
What is swine influenza?
Influenza Defined
Influenza Viruses - Types, Subtypes, and Strains
What is pandemic influenza A(H1N1) 2009 virus?
Definitions for identification of pandemic influenza A(H1N1) 2009
Case Management & Infection Control
Who should be tested?
Step-by-step guide for specimen collection, storage and transportation
Doctors/Nurses directions to Patients/Parents
How Influenza Viruses Change: Drift and Shift
The 2009 Influenza Pandemic
International Health Regulations
Vaccine Development and Use
Naming the Virus Strain
Information for Families and Visitors
New Pandemic Influenza A (H1N1) 2009
Pandemic (H1N1) 2009 Influenza Guidance
Recent Results from Studies with the new 2009 A/H1N1 Influenza A Virus
Continued pandemic influenza virus detections across Europe with increased activity in the UK (Northern Ireland)
Highly Pathogenic Avian Influenza Virus H5N1 and Wild Birds