Nexus Research Group - Information about Influenza A (H1N1) Mexican Swine Flu in New Zealand

Information about non-seasonal Influenza-A H1N1 2009 in New Zealand - Swine flu facts

by Medical Microbiologist / Teacher Michael Fenton

(Microsoft Innovative Teacher, Ministry of Education eLearning Fellow)

Public interest

This article reamains for three reasons

For historical purposes
To show that public health is not just about policy...unless it is properly implemented we rely on luck as much as science!
Unless we learn from our mistakes, we will need to be lucky again when the next pandemic arises

First, the good news...the strain of swine flu is 'mild' compared to the worst case scenario that the Ministry of Health pandemic plan was prepared for

Unfortunately, in practice;

1) Anecdotally, schools did an inconsistent job of implementing the pandemic hygiene practices

2) The Minsitry of Education and Ministry of Health officials I spoke to admitted there were 'crossed wires' about who had authority to close schools or send students home.

3) The pandemic plan was written on the basis of the more severe avian flu scenario and the alert colour codes and actions were not adequately amended for the new pandemic

4) Ministry officials did not independently verify that schools were properly implementing hygiene and isolation procedures.

5) Officials denied there was any confusion or inconsistancies in pandemic preparedness plans even after these were pointed out

What is the 'Flu?

The illness commonly referred to as the 'flu is more properly called influenza.

Influenza is a viral infection of the lungs characterised by fever, cough, and severe muscle aches. In the elderly and infirm, it is a major cause of disability and death (often as a result of secondary infection of the lungs by bacteria).

Influenza is not a case of low fever and sniffles that keeps you home in bed for a day , or a gastrointestinal upset ("stomach flu")

True influenza is an acute infectious disease caused by a member of the orthomyxovirus family.

This electron micrograph (courtesy of Dr. K. G. Murti) shows several influenza virus particles at a magnification of about 284,000 times.

In general, to give an idea of scale, the host cell that will be the target of the virus is about 500 times bigger than the virus itself...

Some strains of influenza A seen in the past:

1918	H1N1	Spanish flu
1957	H2N2	Asian flu
1968	H3N2	Hong Kong flu
1976	H1N1	Swine flu

Non-seasonal Influenza A (H1N1) 2009, aka Mexican Swine Flu;

According the Centre for Disease Control (CDC) Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza that regularly cause outbreaks of influenza among pigs.

Swine flu viruses do not normally infect humans, however, human infections with swine flu do occur, and cases of human-to-human spread of swine flu viruses has been documented.

An influenza pandemic occurs when a new strain of influenza virus emerges, spreading around the world and infecting many people at once.

The World Health Organisation (WHO) declared that a pandemic situation existed in 2009 and individual countries had to take responsiblity for managing outbreaks of non-seasonal influenza (H1N1 swine flu).

What are the symptoms of Swine Flu in Humans?

fever
cough
sore throat
muscle aches
eye infections
pneumonia

Spread

The virus is spread person to person via small particle aerosols (less than 10μm) which can get into respiratory tract.
It can also survive for a short time on surfaces and can be spread by this route if the virus is introduced into the nasal mucosa before it loses infectivity.
The incubation period is short, about 18 to 72 hours.

Site of infection

Influenza virus infects the epithelial cells of the respiratory tract.
The cells die, in part due to the direct effects of the virus on the cell, and also possibly due to the effects of interferon.
There is reduced clearance of infectious agents from the respiratory tract.
Gaps in the protective epithelium provide other pathogens with access to other cells (secondary infection results).

In a study led by Yoshihiro Kawaoka of the University of Wisconsin, the novel H1N1 (swine) influenza shows some resemblance to the virus strain that caused the 1918 flu pandemic, with a greater ability to infect the lungs than common seasonal flu viruses.

The information supplied to the public often claims that Swine Flu results in moderate illness but Kawaoka said that does not mean it is like seasonal flu. While media reports often compare the new virus to seasonal flu, this H1N1 strain is more accurately described as a 'distant cousin' to seasonal flu.

"There is a misunderstanding about this virus," he said in a statement. "There is clear evidence the virus is different than seasonal influenza."

The new Swine Flu strain can spread beyond the upper respiratory tract to go deep into the lungs -- making it more likely to cause pneumonia, the international team said.

Other studies support these findings

Do face masks filter out swine flu viruses?

Normal face masks are NO GOOD at preventing Swine Flu viruses from passing through.

In the local paper (Taranaki Daily News) was a report that a pharmacy was running out of face masks, such was the demand by the public.

The bad news is that the pore size (size of the 'holes' in the material used to make the masks) is very large compared to the Swine Flu virion.

So what kind of masks SHOULD you be using? The CDC suggests that masks rated N95 or higher be used. The '95' rating means that the mask will stop 95% of particles that are 0.3 micrometers or larger in size. In comparison, large aerosol droplets in the air containing flu virus are about 0.5 micrometers in size, too big to pass through the N95 mask but way too small to be blocked by the masks sold in hardware stores or pharmacies. N95 masks are also form fitting to the face for a snug, tight fit. They are also expensive and in limited supply.

What cheap face masks ARE good for is to prevent spit and sneezes from spraying surfaces or people nearby. Wearing a paper or cloth mask may also make the person feel better psychologically. These masks should be disposed of after a single use followed by thorough hand washing (see the advice below from Dr Peters).

Treatments for Swine Flu

Viruses are not living therefore they cannot be killed. For this reason anitbiotics cannot be used* to kill influenza viruses. If viruses are not alive, how does one virus in your body become millions? Your own cells, once infected by a virus, are 'tricked' into producing more virus particles.

* [I said that antibiotics are of absolutely no value against the flu virus. However, they are often given to patients to combat the secondary bacterial infections that occur and that are usually the main cause of serious illness and death. ]

If you can not kill the virus, the two main strategies used include:

Immunisation

A number of countries reported that the virus had mutated and become resistant to Tamiflu. An alternative does exist and the New Zealand Ministry of Health stocked up on the alternative drug Rilenza.

Reye's syndrome is rare, but approximately 40% of cases are fatal. The effects on the liver and brain are particularly serious. The origin of Reye's syndrome is unclear but seems to follow certain viral infections such as influenza or chicken pox (varicella zoster/herpes zoster), especially if they are in the young and especially if they have been treated with aspirin. Aspirin is contraindicated for childhood or adolescent fevers because it is a risk factor in the development Reye's syndrome. Acetaminophen and Ibuprofen are apparently not associated with Reye's syndrome. Recent media reports in New Zealand about using Bonjela reflected findings that salicylate salts are not recommended for children under 16.

Controlling the spread of Swine Flu

The World Health Organization (WHO) maintains constant surveillance of influenza outbreaks world wide and has a series of 'sentinel' labs to look at what is happening in the circulating virus population.

The New Zealand Ministry of Health (MoH) is in contact with the Centre for Disease Control (CDC) and the World Health Organisation (WHO).

Dr Julia Peters Clinical Director of ARPHS suggests

stay at home and away from others if you are sick
cover your coughs and sneezes with a tissue
put used tissues into a rubbish bin
avoid touching your eyes, nose or mouth – germs spread that way
be careful to wash hands often with soap and dry them thoroughly – hand hygiene is critical: even when you start to feel better there is still a risk of infecting others, so keep to the 20/20 rule – 20 seconds washing and 20 seconds drying
keep surfaces clean at home, school and work.

A couple of extra suggestions:

Eat healthily - good nutrition is essential to maintaining your immune system.
Relax and do not worry too much - stress is not good for the immune system either!

When there is an influenza pandemic, what happens?

When a pandemic does occur, there are laws that will supersede others. The Ministry of Health will have the ability to close public places such as schools, cinemas, etc to prevent the spread of disease.

In New Zealand, for planning purposes the different stages of the health response in an influenza pandemic have been grouped and defined with colour codes: Code White, Code Yellow, Code Red and Code Green.

More information on these alert codes is included in the New Zealand Influenza Pandemic Action Plan. In summary the codes mean:

School pandemic plan

According to staff I have spoken to at the Minsitry of Health and the Ministry of Education, it is expected schools WILL follow the recommendations outlined in the Pandemic Planning kit from the MoE website

Failure to do so means schools are not meeting their legal obligations under the National Adminstration Guidelines (NAGs) or the Health and Safety Act 1992.