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.
]]>Table of contents for this article
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.
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]]>The post Celebs who might have been saved by a pathology test first appeared on Know Pathology Know Healthcare.
]]>Eva Peron
Eva Peron’s life has all the touchstones of high drama. Born in a poor village she left for Buenos Aires to pursue an acting career when she met and married future Argentine President, Juan Peron. No shrinking political violet, she ran the ministries of labour and health. Her life’s story has proven irresistible – spawning endless books, films, television series and the musical Evita.
After fainting at a public event in 1950, it was discovered she had advanced cervical cancer. She died soon after in 1952, aged 33. The basis of cervical cancer is the Human papilloma virus (HPV), which today can be picked by an HPV pathology test. Replacing the pap smear test in 2017, the HPV test can be taken every 5 years.
Vivien Leigh
Vivien Leigh made her name in two of Hollywood’s great mid-century blockbusters, Gone with the Wind and A Streetcar Named Desire. Shortly after starring in Gone with the Wind and marrying Laurence Olivier, she was diagnosed with tuberculosis, a condition she had recurrent bouts of and which killed her at age 53.
Today, a quarter of the world’s population carry the Mycobacterium tuberculosis bacteria that leads to tuberculosis, but only 5-10% will get sick. Those with weakened immune systems or with already damaged lungs are most susceptible. There are several tests available for tuberculosis which is treatable with a course of medication.
Freddie Mercury
The best-known Zoroastrian in the world – also known as the lead singer and songwriter of rock outfit, Queen – Freddie Mercury died as a result of AIDS in 1991 at 45 after being diagnosed with the condition in 1986. His life was unfortunately just out of sync with the development of HIV medicines, the first experimental AIDS vaccine tested in the US declared safe in 1991.
While Freddie might not have benefitted from early detection of HIV given the medical treatment for HIV was not yet developed commercially, today, anyone else can have an HIV test, and if found positive can seek treatment before it develops into AIDS.
Al Capone
Ultimately nabbed by the United States government for tax evasion and given an 11-year spell in the Atlanta Penitentiary and Alcatraz, Al Capone made his fortune during the Prohibition as a Chicago mobster. It was up like a rocket and down like a stick for Capone. By the ripe age of 33 he was in prison, being released 8 years later.
But his freedom wasn’t what it might have been. At some stage Capone contracted syphilis and upon his release in 1947 was suffering syphilitic dementia. A simple syphilis test for the pathogen Treponema pallidum would have revealed the condition and a course of penicillin would have cured him.
Wolfgang Amadeus Mozart
A workhorse to the end, Wolfgang Amadeus Mozart was still composing his last masterpiece ‘Requiem’ on his deathbed when he struck a final, sour note, dying at the age of 35, having produced an unbelievable body of work. The cause? As happens in old cases, theories abound, but it’s argued that new evidence points to the cause of death as being kidney damage caused by strep throat.
There was an epidemic of strep throat in 1791. The culprit, the Streptococcus pyogenes bacteria. A simple Rapid antigen or throat culture test can detect strep throat and then a course of antibiotics is all you need to clear it up. Unless it was death by pork chop, as suggested here. Either way his premature death was a tragic conclusion for Wolfy and the human race.
That the world was deprived of the unique talents of so many people is sad but also points to how far we’ve come in the detection of medical conditions.
‘Today, we’re extremely fortunate that we can pick up on conditions early so that appropriate medical treatment can begin,’ says microbiologist, Dr Petra Derrington.
‘With the developments in testing and medical treatments over the last century or so, conditions that once proved fatal, need not be the tragedies they once were.’
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]]>The post The case for targeted preventive healthcare first appeared on Know Pathology Know Healthcare.
]]>But according to an article by The New England Journal of Medicine (NEJM) from 2008, the economic case for preventive healthcare spending is by no means clear cut. In some cases – like flu vaccinations or colonoscopies – there is a health benefit and cost saving, in other cases the cost-benefit is negligible or poor.
In the first phase of preventive medicine, proponents suggested better health and economic outcomes were possible through early detection of conditions, only to have detractors point out the enormous scope of the enterprise, warning about misleading statements about its supposed benefits.
Up like a rocket, down like a stick: the case for spending on preventive healthcare seemed to be knocked into a cocked hat, a medical cul-de-sac. Or perhaps not.
A recent 2017 Australian study by La Trobe University’s Department of Public Health, suggests that preventive medicine does indeed have an important role to play in the Australian health landscape, stating ‘There is clear evidence that many preventive health interventions are cost-effective.’
Like the NEJM article, the La Trobe study’s authors accept that spending on preventive healthcare is not a panacea for all cases and needs to be strategically targeted, but the benefits of doing so could be significant.
Referencing the 2010 Assessing Cost-Effectiveness (ACE) in Prevention study by the University of Queensland and Deakin University – which looks at the benefits of campaigns around tobacco, alcohol, unhealthy foods, gastric banding, and a raft of other measures – the La Trobe study authors state ‘the evidence considered suggests a strong case can be made for increasing spending on preventive health.’
As Michael Thorn of the Foundation for Alcohol Research and Education (FARE) points out, a third of all chronic diseases are preventable and can be traced back to four lifestyle factors: alcohol use, tobacco use, physical inactivity, and poor nutrition. Preventive medicine in those areas, from education to pathology tests, would make sense.
One area of health that certainly would benefit from preventive healthcare spending is on type 2 diabetes. Indeed the case for a national roll-out of the relatively new HbA1c test – which measures glycated haemoglobin in the body – is strong.
In a 2016 trial program run at Mt Druitt Hospital in Blacktown, anyone over 18 presenting to the Emergency Department for blood tests were also given the HbA1c test. The findings were striking.
In the two years from mid-2016 to mid-2018, 48,000 samples were taken, with 47 per cent of those tested presenting with diabetes or prediabetes.
While Blacktown is in the electorate of Chifley, the seat with the highest incidence of diabetes in Australia at 7.8 per cent, the residence of Chifley are not exactly outliers. The national diabetes average is 6 per cent, with 1.2 million Australians living with diagnosed diabetes and a further 500,000 thought to be living with undiagnosed diabetes.
According to the the Centre for International Economics (CIE) 2018 report the prognosis for diabetes in the future is alarming, with 3.5 million Australians projected to be living with diabetes by 2030.
A person can have diabetes for seven years before it symptoms are evident, during which time it’s doing damage to the body. Fortunately, the Centre for International Economics (CIE) 2018 report states that if diabetes is detected and treated early before macrovascular complications ensue, it can more than halve treatment costs.
Given the direct costs of diabetes to the health budget are $1.7 billion a year, with indirect costs to the economy as high as $14 billion, a preventive health program that can significantly cut treatment costs seems like an absolute no brainer.
While it’s not feasible to test every Australian for every condition, that does not preclude smart, targeted testing for specific conditions, such as the bowel screening test for those aged 50-74, diabetes testing for those with a waistline over 102cms, or cervical testing for women with human papillomavirus (HPV), immune deficiency and other risk factors.
Government spending on pathology services in Australia represents just 2.7 per cent of the health budget, while 70 per cent of medical treatment decisions rely on pathology.
With Medicare spending forecast to climb over 25 per cent by 2027-28 from $855 to $1,071 per person that puts even more of a premium on finding ways to reduce health costs by way of preventative medicine, of which pathology testing is central.
So rather than throw the baby out with bathwater, we suggest some targeted funding for targeted testing campaigns that can deliver those health and economic outcomes we all hope for.
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]]>The post Cervical screening changes in depth: what, why and how first appeared on Know Pathology Know Healthcare.
]]>The changes to the government’s national cervical screening program came into effect across Australia in December 2017, but what are the changes and what do they mean for patients?
The test
Previously all Pap tests were performed in pathology laboratories and this is the same with the new test.
The sample is also collected in the same way as the previous Pap test. Cells are collected from the cervix using a spatula or ‘brush’ device.
What has changed is the test performed on the sample once it reaches the pathology lab, and what the sample is being tested for.
The previous test looked for abnormal cells in the sample which may indicate cancer, precancerous cells, or other changes in the body, such as a virus or infection. This was done by a pathology professional looking at the sample under a microscope.
The new test detects the presence of the Human Papillomavirus (HPV) and is conducted using a machine operated by highly skilled pathology staff. It is more sensitive and has good accuracy in specifically detecting HPV. There are over 100 types of HPV but two of these are heavily associated with cancer; HPV 16 causes 55-60% of cervical cancers and HPV 18 causes 10-15%. In the unvaccinated population, HPV is very common as both men and women can be affected and it can be easily passed between sexual partners.
Why?
Identifying HPV allows doctors to know if a woman is at higher risk of cervical cancer prior to abnormal cells appearing.
The introduction of the HPV vaccination program in 2007 for young women, and in 2012 for young men, means younger generations of Australian women have a much lower risk of cervical cancer.
It has been predicted that rates of cervical cancer could fall a further 15% with this new type of screening, combined with the new landscape of many more people being vaccinated against HPV.
Due to the test’s ability to detect HPV, testing frequency has dropped to every 5 years. However, like all tests there can be false negative results and if there are any worrying symptoms or signs then a woman should see her doctor.
What this means for women
It is important that all women continue to be tested regularly, even those who have been vaccinated.
There is currently no anti-viral drug available that can treat HPV and although the vaccine protects against HPV 16 and 18, it does not provide immunity to all types of HPV.
“Current Pap testing has dramatically reduced the mortality rate of cervical cancer in Australia and it is hoped that this new testing method will be able to identify those at high risk of developing cancer even earlier,” said A/Prof Annabelle Farnsworth, a specialist in cytopathology and gynaecological pathology.
What next?
- All women between the ages of 25 and 74 should be tested every 5 years, even if you have been vaccinated for HPV.
- However, women with any symptoms or signs of potential cervical disease such as abnormal vaginal bleeding can be tested as needed.
- The test in the new screening program will specifically identify all types of HPV, including types 16 and 18. There is currently no anti-viral drug for HPV, so vaccination and screening are imperative preventative measures.
- If a woman is found to have HPV, a cytology sample (cells to be examined under a microscope) will be prepared immediately. Depending on the nature of the HPV found and the cytology result she will be referred for further investigation. Many HPV infections are dealt with naturally by the body but persistent HPV infections could be a problem and the new test will help to identify these.
- The type of HPV test used in screening has little bearing on whether the woman may have had HPV in the past and her current immunity so vaccination cannot be administered for all women who test negative. However, if a woman is interested in vaccination at any time she should discuss this with her doctor.
To find out how Pap tests were created, listen to Dr Clare Hampson’s engaging Laborastory presentation on George and Mary Papanicolaou.
1 Australian Government Department of Health –
http://www.cancerscreening.gov.au/internet/screening/publishing.nsf/Content/future-changes-cervical
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