Table of contents for this article

• • What is a virus
  • How does a virus spread?
  • The difference between Viruses and bacteria
  • Common viral infections

What is a virus?

Viruses are small groups of genetic code, such as DNA or RNA, enclosed within a shell of protein. A virus cannot survive or multiply on its own, nor can it obtain or store energy. It requires a living organism, or host, which it must inhabit to perform these functions that are basic to life. Hosts can be bacteria, plants, or animals,including human beings.

The incapability of a virus to survive without a host means that they are classed as non-living entities.

Some viruses, like the coronavirus SARS-CoV-2 behind COVID-19, infect the host for a number of days or weeks before being cleared from the system. Other viruses, like varicella-zoster that causes chickenpox, and the human immunodeficiency virus (HIV), can sit dormant in a host without causing an active infection for a number of years.

Read here to find out what happens when you’ve had a Covid test, from collection to results

How does a virus spread?

Most people are now aware that the SARS-CoV-2 virus can be spread through respiratory infection symptoms such as sneezing and coughing, and can also be spread through actions such as speaking or breathing.

There are four primary forms of transmission in which viruses spread:

1. Airborne transmission: Airborne transmission occurs when infected viral droplets in the air are inhaled by another living organism. Airborne transmission is how COVID-19 is commonly spread.

2. Vehicle transmission: Vehicle transmission occurs when food, water, body fluids, or inanimate objects passively carry the virus and transmit it when they come in contact with a potential host organism.

3. Direct transmission: Direct contact transmission occurs when viral particles are spread through physical contact between an infected and uninfected animal, plant, or human being. Examples include ingesting infected foodstuffs or transmission via kissing or sexual activity.

4. Indirect transmission: Indirect contact transmission occurs when the viral particles are spread via contact with contaminated materials such as unsterile medical equipment.

Difference between Viruses and bacteria

On the surface of it, viruses and bacteria may seem very similar. They are spread from human to human in very similar ways and can have similar ravaging effects on human bodies. However, there are in fact far more differences than similarities between them.

Viruses are much smaller than bacteria, and even the largest virus is tinier than the smallest bacterium.

A virus needs a living host to survive, thrive and multiply. This is not the case for bacteria, and they can live independently in almost any environment.

Treatment for bacterial infection is primarily via antibiotics. Antibiotics do not have an effect on viruses, which are generally treated with anti-viral agents where available.

Vaccines are an important preventive agent against viruses.

Common viral infections

• Coronavirus
• Influenza – causes ‘the ‘flu’
• Rhinoviruses – cause the ‘common cold’
• Human papillomavirus (HPV) – causes genital warts and cervical cancer
• Varicella-zoster – causes chickenpox
• Noroviruses – cause vomiting and diarrhoea
• Measles
• Mumps

What is the endgame of a virus?

From an evolutionary perspective, the ‘perfect’ virus is one that infects as many hosts as possible to replicate, without killing the host in the process, because the host is needed to aid transmission. The SARS-CoV-2 virus does this very well. Most infected people don’t die from the infection, and it has a relatively long incubation period, which is the time from infection to the point where symptoms are first displayed. This, and the highly effective manner in which it is transmitted through the air, make it a very successful virus.

The post What is a virus: How viruses spread, how they differ from bacteria, and common viral infections first appeared on Know Pathology Know Healthcare.

But for those who still find themselves suffering from flu like symptoms, it’s essential that they get diagnosed, not only for their own benefit but for the benefit of the community.

At St Vincent’s Hospital, Melbourne rapid flu testing has made a vast difference in how emergency departments handle the influx of patients that come during the flu season.

“Our new rapid flu analyser is a molecular diagnostic tool that we use here at St Vincent’s for diagnosis of infectious diseases,” explains Dr Darren Jardine, Manager of Microbiology at St Vincent’s.

“We predominantly use it for rapid flu testing, norovirus, and a lot of resistant bugs that are out there. It’s very important to ensure we are effectively containing any infections.”

This new technology has helped decrease the pressure put on the emergency department. Prior to its installation testing took too long – anywhere from 7-8 hours before a diagnosis. Now, this rapid flu testing can be done in under an hour.

“Each flu season can be quite unpredictable. We need to be prepared to make sure that we’re able to rapidly process patients in the emergency department,” says Dr Jonty Karro, Deputy Director of the Emergency Department.

One of the challenges is that a patient who potentially has the flu cannot be admitted or discharged until there is a diagnosis. There is also a level of quarantine around them as the flu is highly contagious and there are other vulnerable patients nearby. This often leads to a bed shortage.

“It’s not uncommon during influenza season for us to suffer a bed crisis. Beds are in demand during the flu season, and we need to optimise our usage of that very scarce resource,” says Dr Karro.

Investment in pathology technology has supported the emergency department in becoming more efficient in managing their patients.

“We were fortunate enough to be given funding through the Department of Health and Human Services, and the lab suggested that this is the technology that we should invest in to ensure that our rapid flu testing is improved and enhanced for our patients,” says Jacqui Bilo, General Manager, Medical Services & Emergency.

“We’re now able to perform up to 100 tests per day. Prior to that we were only able to respond to about 30, which is quite a significant improvement for us,” says Ms Bilo.

Now, it’s expected that rapid flu testing will ease the burden experienced in previous flu seasons with high prevalence and fatalities.

“A couple of years ago, we had a particularly bad flu season here in Victoria, during which we found that we just weren’t able to maintain the service that was required by the hospital,” says Dr Jardine.

“Having our new rapid flu analyser has been a game changer for us in the emergency department. We can rapidly know whether patients do or don’t have influenza,” says Dr Karro.

The post How rapid flu testing has eased winter woes in this Melbourne hospital first appeared on Know Pathology Know Healthcare.

The 2018 and 2019 flu seasons are morphing into each other, with a remarkably high number of cases during the summer and autumn months.

“It is really unusual that we have had continued flu and have not returned to our usual baseline,” says Dr Jenny Robson, a clinical microbiologist and infectious disease physician at Sullivan Nicolaides Pathology in Queensland.

She says flu season usually peaks between May and October when there is a surge in cases after a marked drop-off in summer. But this year has been different, according to national Department of Health figures and the infections barometer on Sullivan Nicolaides Pathology’s website.

Dr Robson says it is not yet possible to predict how bad the 2019 flu strains will be, but there have already been more than 60 flu-related deaths this year. She says that the main advantages of having a flu test is that it allows GPs to prescribe antiviral medication in a timely manner particularly to those at high risk of complications such as the elderly, the very young and those who have chronic medical conditions.

Testing also rules out the need for antibiotics as there is no reason to give antibiotics for a flu virus unless the patient has a complication that involves a bacterial infection. Patients should not expect to be prescribed an antibiotic for the flu.

About 40% of influenza tests performed by Dr Robson’s laboratory prove positive for flu at peak season, but most modern laboratories typically perform a suite of tests that excludes or confirms several other important viruses, such as respiratory syncytial virus, parainfluenza virus and human metapneumovirus.

“People like to know what their diagnosis is. And doctors get a lot more information from tests these days. It is important to know what other viruses are circulating, which is why we publish weekly data on our website.”

Dr Robson says having a test has several other advantages for patients with flu-like symptoms:

• It is possible to get a diagnosis quickly, often within 24 hours.
• If patients know they have flu, they are more likely to stay at home and take care not to infect other people.
• GPs can find out if the patient is in contact with high-risk people and offer preventative antivirals.
• The information collected by pathologists helps determine how the circulating virus has changed compared with previous years, which is essential for the development of an effective vaccine for the next year.
• Resistance to antiviral treatments can be monitored.

*IMAGE CREDIT: Influenza A virus H3N2, part of the Vivid Sydney installation Beautiful and Dangerous. https://blog.csiro.au/australia-braces-for-flu-season-100-years-after-spanish-influenza-killed-one-in-10/ 

The post Australia’s never-ending flu season first appeared on Know Pathology Know Healthcare.

Rapid flu tests have also been introduced this year by New South Wales Health Pathology in NSW public hospitals, and are available in various other locations. The influenza season has also started earlier than in previous seasons.

Influenza is a notifiable disease meaning confirmed cases are recorded by the National Notifiable Diseases Surveillance System (NNDSS). The only way to definitively confirm a case of influenza is via pathology testing.

The influenza virus is detected using a method known as Polymerase Chain Reaction (PCR) where the sample is processed in a thermocycler machine that makes many copies of the flu virus RNA (genetic make-up) which is then examined. The sample used is usually a nasopharyngeal swab – taken from the back of a patient’s nasal passages.

The 2017 flu vaccine has been updated to include the four most common strains of influenza that are circulating this year to offer the best protection. These are the A/H3N2 Hong Kong strain, B/Phuket and B/Brisbane strains plus the A/H1N1 Michigan strain that replaces the A/H1N1 California strain, which was included in last year’s vaccine.

Rapid testing is particularly useful in hospital settings and allows anti-viral medications to be provided early to confirmed cases. These can reduce the duration and severity of a bout of influenza and in high risk patients can be life-saving. Outbreaks in nursing homes this year have sparked concern, and several elderly people with underlying health conditions have died from influenza in 2017.

Although many cases of influenza can be managed at home and with the advice of general practitioners, cases in vulnerable populations such as young children, older Australians or those with a compromised immune system may end up in hospital.

This is where rapid testing has additional importance in establishing the cause of symptoms and directing treatment.

The Immunisation Coalition has stated that more than 70,000 cases of influenza have been confirmed in Australia this year via pathology testing.

Professor Dominic Dwyer from New South Wales Health Pathology says it is possible that up to twenty percent of the population will have caught influenza by the end of the year, and that rapid testing allows flu cases to be identified earlier. He said;

“The rapid tests now being used in much of New South Wales reduce the time to diagnosis to around an hour. When cases are caught early, within 48 hours of the onset of symptoms, patients can benefit from antiviral medication.

Although we predict that around 20 percent of the population will be affected by influenza this year, most patients choose to be managed at home, and those presenting to GPs may not necessarily be tested.”

There have been increased numbers of hospital presentations in NSW for flu and this is in part due to one of the common strains this year being particularly nasty.

The H2N3 (A/Hong Kong) strain has dominated so far this year and tends to affect children and older adults, hence the nursing home cases and reported rise in influenza presentations at children’s hospitals in Sydney.

Dr Petra Derrington, from Pathology Queensland says that more flu cases are being seen in her state.

“Currently, we are seeing an increase in the numbers of influenza diagnosed in Queensland, which is not due to increased testing.  We are seeing a 40% positivity rate for influenza versus a 20% rate at the same time last year and a baseline rate of about 5% in preceding months.  Compared to last month, August is showing a doubling of the positivity rate.

Vaccination is strongly recommended at this time when the incidence of influenza is increasing, particularly for the elderly and the immunocompromised.”

The availability of the flu vaccine via general practice and pharmacies makes immunisation increasingly accessible and Prof Dwyer is also keen to point out that; “It’s never too late to be vaccinated.”

Reference materials:

http://www.msn.com/en-au/news/australia/%E2%80%98rapid-flu-test%E2%80%99-rolled-out-at-nsw-public-hospitals/ar-AAoEq23
https://www.australiandoctor.com.au/news/latest-news/70-000-cases-of-flu-reported
http://www.afr.com/business/health/the-most-severe-flu-season-since-2009-has-not-yet-peaked-20170811-gxu6ut

The post More flu cases or just more flu tests – is this really the worst flu season since 2009? first appeared on Know Pathology Know Healthcare.

According to figures from the Influenza Specialist Group* (ISG) there were over 100,000 laboratory confirmed cases of flu last year, which was an increase in laboratory diagnosis of almost fifty percent on the previous year, in part due to better testing.

Although flu isn’t life threatening for most people, ISG data shows it contributes to between 1,500 – 3,500 deaths a year, and vaccination is recommended for at risk groups. This includes people with underlying health conditions such as asthma or heart disease.

Pathology is the only way to diagnose flu, and this is particularly important as the symptoms are non-specific and mirror those of other conditions.

Influenza is a ‘notifiable disease’ meaning that diagnosed cases are recorded on the National Notifiable Diseases Surveillance System. The data is provided directly from the pathology laboratories that make the diagnosis.

Most people who contract the flu will get better at home but a minority of people will get sick enough to visit their doctor or even need admission to hospital.

Initial pathology testing is important to ensure that flu is the cause of symptoms. Further testing can also ascertain any secondary infection the patient may have, such as bacterial pneumonia or staphylococcus infection, which would require antibiotic treatment.

The flu virus is detected using a method known as Polymerase Chain Reaction (PCR) where the sample is processed in a thermocycler machine that makes lots of copies of the flu virus RNA (genetic make up) which is then examined.

Samples may also be sent for more detailed testing to isolate the specific type of flu virus. This information is sent from hospital laboratories to the World Health Organisation’s (WHO) reference centre located in Melbourne.

Although many flu cases will be diagnosed in hospitals, in some instances General Practitioners will also order flu tests, particularly if they are part of a surveillance network.

These surveillance networks help to monitor trends, including the instance of flu in the community and the severity of symptoms, by testing patients with flu-like symptoms.

As well as being provided to state and federal health departments this data will also be provided to the WHO.

The RNA of the flu virus mutates quickly and new strains can appear from year to year, which means that the flu vaccine must be reviewed each year to keep up with the virus and continue offering protection.

The data provided by Australian hospitals and GPs is combined with other global data and used by the WHO to help develop the vaccine for the following year.

Any new strains emerging will be catalogued and named. Flu viruses are categorised into A and B as they have different characteristics, for example influenza B strains do not circulate in animals.

New strains are usually named after the place where they appeared, hence this year’s quadrivalent (QIV) flu vaccine, protects against four strains of the flu;

• A/California
• A/Hong Kong
• B/Brisbane
• B/Phuket

Despite the exotic destination names, anyone catching one of these will most likely be staying in bed.

* http://www.isg.org.au/index.php/media/flu-fact-sheet/

^{Image of influenza under microscope: http://www.who.int/influenza/gisrs_laboratory/en/}

The post California, Hong Kong or Brisbane; where are you headed this flu season? first appeared on Know Pathology Know Healthcare.