September 23, 2022
2 min read
Fears of polio gripped the US in the mid-20th century. Parents were afraid to send their children to birthday parties, public pools or any place where children mingled. Children in wheelchairs served as a stark reminder of the ravages of the disease.
To prevent polio outbreaks, government officials used tactics now familiar in the era of COVID-19: They closed public spaces and shut down restaurants, pools and other gathering places.
In 1952, two years prior to the introduction of a trial polio vaccine, there were an estimated 58,000 cases of polio and 3,145 deaths due to polio in the US. These cases included children who were paralysed for life. But those numbers dropped dramatically following a widespread vaccination campaign against polio, beginning in 1955.
By the 1970s, there were fewer than 10 cases of paralysis due to polio in the US, and the polio virus was considered eliminated from the US by 1979. Since then, collective fear of the virus has been mostly lost to history – many people alive today are lucky enough not to know someone who has experienced polio.
So when news broke in July 2022 that an unvaccinated adult man in New York had contracted polio – the first case in the US since 2013 – and developed paralysis from the disease, it sent a ripple of fear throughout the public health community and raised the question of whether an old foe was making a comeback.
I am a virologist and a professor of immunology and microbiology and have spent my career both teaching about and doing research on how viruses can cause disease.
There is no cure for polio. The only treatment is prevention. And the tool for prevention is vaccination, the same tool that eliminated polio in the US in the first place.
Life cycle of the poliovirus
Polio – or poliomyelitis – the disease, is caused by the poliovirus, which is passed from person to person through the mouth. And while no one would knowingly ingest a virus, touching a contaminated object like a spoon or a glass or accidentally swallowing contaminated water can unknowingly lead to infection.
When someone is infected with the poliovirus, they shed the infectious virus in their faeces. This is why recent reports that poliovirus has been circulating in New York City wastewater for months and that the virus now has been detected in three New York counties are particularly concerning.
In August 2022, New York State Health Commissioner Mary Basset said that the state health department is “treating the single case of polio as just the tip of the iceberg of much greater potential spread”.
“Based on earlier polio outbreaks,” she added, “New Yorkers should know that for every one case of paralytic polio observed, there may be hundreds of other people infected.”
A single case of polio reflects a larger potential spread of the virus because most people infected either don’t show any symptoms or have a very mild illness with symptoms similar to the flu. But even without symptoms, an infected person is still excreting virus in their faeces, which means they can be a source of infection to others.
The virus, which is very stable in the environment, is easily spread through surface contamination. For this reason, hand-washing is a critical prevention tool. Although many disinfecting agents, such as alcohol or diluted Lysol, fail to inactivate the virus, chlorine bleach does destroy it. This is why public health officials started chlorinating swimming pools decades ago in order to inactivate the polio virus.
Typically, the human body uses stomach acid to protect against ingested viruses. But poliovirus can survive stomach acid to travel to your gastrointestinal tract. There, the virus reproduces itself to establish an infection.
What is paralytic polio?
Unfortunately, one person out of about 200 people infected with poliovirus will develop paralysis. Scientists still don’t know why one person is susceptible to the paralytic disease while most are not.
In the small subset of people that get paralytic polio, the virus can attack the lower motor neurons found in the brain stem and spinal cord, which are important for controlling muscles. Infection of those neurons leads to the muscle paralysis that is characteristic of paralytic polio. The legs are typically affected – often on only one side of the body – and paralysis can range from mild to severe. Other muscle groups can also be affected.
In the worst cases of paralytic polio, the virus can damage the centers of the nervous system that control breathing. Respirators known as “iron lungs” were early medical devices that aided those with damaged respiratory muscles, helping them breathe until their muscles healed enough to work on their own. Patients could die when the paralysis was severe and sustained.
Levels of severity
Although polio can be devastating for those who contract the severe form of it, most people’s immune systems are well-equipped to combat it. When someone recovers from polio, researchers can detect poliovirus-fighting antibodies in the blood.
But even long-term survivors of paralytic polio can develop late-onset muscle weakness and fatigue, which is known as post-polio syndrome. While the muscular effects of post-polio syndrome are well-recognised, a number of other symptoms can be associated with post-polio syndrome, including chronic pain, sleep disturbances, cold intolerance and difficulty swallowing.
Because post-polio syndrome is diagnosed only based on symptoms, there is no consensus on the number of polio survivors who develop it, but estimates range from 15% to upward of 80%.
Prevention of polio is key
The decline in polio in the US and globally is a direct result of the introduction of vaccines and the willingness of the public to accept them. In 1988, the World Health Organisation, in partnership with Rotary International, the Centres for Disease Control and Prevention and other national governments, launched the Global Polio Eradication Initiative with the goal to wipe out polio worldwide, as is the case with smallpox.
When this initiative was launched, there were still an estimated 350,000 children with polio in 125 countries. In 2021, there were only six reported cases.
Two types of polio vaccine are in use worldwide. The one used in the US since 2000 is an injection made from inactivated poliovirus. Inactivation kills the virus and prevents it from spreading. Children in the US get this shot at 2 months, 4 months and between 6 to 15 months of age, and it essentially provides lifelong protection from polio.
The second vaccine type, still in use in many parts of the world, is an attenuated – or weakened – form of the virus that is taken orally. In places where community transmission remains significant, like Pakistan, the oral vaccine is preferred because it prevents people from getting polio and also stops person-to-person transmission.
In the US, where person-to-person transmission of the poliovirus has been virtually nonexistent for decades, the inactivated vaccine is preferred since the focus is on preventing disease in the vaccinated person and there’s less concern about spreading the virus.
But in extremely rare cases, the vaccine virus mutates after it’s been excreted in faeces. And if immunisation levels fall below a critical threshold – as is the case in some areas of the world – this poliovirus can cause disease. The recent New York polio case has been traced back to a mutated vaccine-derived poliovirus thought to be acquired overseas.
Most people in the US are vaccinated through routine childhood vaccinations. Because immunity to polio following vaccination is lifelong, the CDC is not recommending booster vaccinations for the general population for people who completed the full series. However, the CDC does recommend that anyone who has not been vaccinated against polio virus get vaccinated, including adults.
In my office, I keep a painting of Dr Jonas Salk, the virologist who developed the first polio vaccine. It serves as my reminder of the importance of biomedical research to help eliminate human suffering caused by infectious diseases.
September 23, 2022
2 min read
One author reports receiving speaker and consultant fees from Bayer and Janssen for work unrelated to this study. Walli-Attaei and the other authors report no relevant financial disclosures.
The magnitude of associations with major CVD for most risk factors are similar in women and men, despite sex differences in risk factor levels, according to an analysis of the PURE study.
In a comprehensive overview of the prevalence of metabolic, behavioral and psychosocial risk factors for CVD in women and men globally, researchers also found that diet was more strongly associated with CVD in women than in men. However, high concentrations of non-HDL and related lipids and symptoms of depression were more strongly associated with risk for CVD in men than in women. Patterns remained consistent across countries regardless of income level.
“Existing studies, mostly from high-income countries, have reported that hypertension, diabetes, and smoking are more strongly associated with cardiovascular disease in women than in men,” Marjan Walli-Attaei, PhD, a research fellow at the Population Health Research Institute of McMaster University and Hamilton Health Sciences, and colleagues wrote in The Lancet. “Such findings would imply that women would benefit to a greater extent in reducing cardiovascular disease risk from control of these risk factors than would men. However, the burden of cardiovascular disease is greatest in low-income and middle-income countries, for which prospective data on the association of risk factors with cardiovascular disease are sparse, with a paucity of analysis by sex.”
Walli-Attaei and colleagues analyzed data from 155,724 adults aged 35 to 70 years at baseline without a history of CVD enrolled in the PURE study, which included participants from 21 high-, middle- and low-income countries, and followed them for approximately 10 years (58% women; mean baseline age, 50 years). Researchers recorded information on participants’ metabolic, behavioral and psychosocial risk factors; all participants had at least one follow-up visit. The primary outcome was a composite of major CV events, defined as CV death, MI, stroke and HF. Researchers reported the prevalence of each risk factor in women and men, HRs and population-attributable fractions associated with major CVD.
As of the data cutoff of Sept. 13, 2021, researchers observed 4,280 major CVD events in women (age-standardized incidence rate, 5 events per 1,000 person-years) and 4,911 in men (age-standardized incidence rate, 8.2 per 1,000 person-years).
Compared with men, women presented with a more favorable CV risk profile, especially at younger ages. HRs for metabolic risk factors were similar in women and men, except for non-HDL, for which high non-HDL was associated with an HR for major CVD of 1.11 in women (95% CI, 1.01-1.21) and 1.28 in men (95% CI, 1.19-1.39; P for interaction = .0037), with a consistent pattern for higher risk among men than women with other lipid markers.
Researchers also observed that maintaining a diet with a PURE score of 4 or lower (score range, 0-8) was more strongly associated with major CVD in women than in men, with HRs of 1.17 (95% CI, 1.08-1.26) and 1.07 (95% CI, 0.99-1.15; P for interaction = .0065), respectively.
In contrast, symptoms of depression were more strongly associated with CVD in men than in women, with the HRs for symptoms of depression being higher in men than in women (P for interaction = .0002). “The HRs of other behavioral and psychosocial risk factors, as well as grip strength and household air pollution, were similar among women and men,” the researchers wrote.
The total population-attributable fractions associated with behavioral and psychosocial risk factors were greater in men than in women (15.7% vs. 8.4%) mostly due to the larger contribution of smoking to population-attributable fractions in men (10.7%) vs. women (1.3%).
“Our results emphasize the importance of a similar strategy for the prevention of cardiovascular disease in both sexes,” the researchers wrote. “However, the increased risk of cardiovascular disease in men might be substantially attenuated with better reductions in tobacco use and lipid concentrations.”
FRIDAY, Sept. 23, 2022 (HealthDay News) — An increased risk of blood clots persists for close to a year after a COVID-19 infection, a large study shows.
The health records of 48 million unvaccinated adults in the United Kingdom suggest that the pandemic’s first wave in 2020 may have led to an additional 10,500 cases of heart attack, stroke and other blood clot complications such as deep vein thrombosis, in England and Wales alone.
The risk of blood clots continues for at least 49 weeks after infection, the study found.
“We have shown that even people who were not hospitalized faced a higher risk of blood clots in the first wave,” said study co-leader Angela Wood, associate director of the British Heart Foundation Data Science Centre.
“While the risk to individuals remains small, the effect on the public’s health could be substantial and strategies to prevent vascular events will be important as we continue through the pandemic,” Wood said in a news release from Health Data Research UK, which sponsors the center.
Researchers found that the risks did lessen over time.
Heart attacks and strokes are mainly caused by blood clots blocking arteries.
The risk of clots in veins was 33 times greater in the week after COVID diagnosis, dropping to eight times greater after four weeks. Conditions caused by these clots include deep vein thrombosis and pulmonary embolism, which can be fatal.
By 26 to 49 weeks after a COVID diagnosis, the risk dropped to 1.3 times more likely for clots in arteries and 1.8 times more likely for clots in veins, the study showed.
While people who were not hospitalized had a lower risk, it was not zero, the study found.
Overall, individual risk remains low, the authors said. Men over 80 years of age are at highest risk.
“We are reassured that the risk drops quite quickly — particularly for heart attacks and strokes — but the finding that it remains elevated for some time highlights the longer-term effects of COVID-19 that we are only beginning to understand,” said study co-leader Jonathan Sterne, director of the NIHR Bristol Biomedical Research Center and of Health Data Research UK South West.
The authors said steps such as giving high-risk patients blood pressure-lowering medication could help reduce cases of serious clots.
Researchers are now studying newer data to understand how vaccination and the impact of new COVID variants may affect blood clotting risks.
The findings were recently published in the journal Circulation.
The U.S. Centers for Disease Control and Prevention has more on blood clots.
SOURCE: Health Data Research UK, news release, Sept. 20, 2022
OTTAWA — An expert told a special joint committee of the House of Commons and Senate that people with mental disorders can suffer for decades, and their distress is equally as valid as someone suffering physical pain.
People suffering solely from mental disorders are due to become eligible for assisted dying in March, and Dr. Justine Dembo, a psychiatrist and medical assistance in dying assessor, also cautioned the committee about perpetuating stigma about mental illness.
Mental health advocates warn it is harder to predict the outcomes and treatments of mental illnesses, and a wish to die is often a symptom, but an expert panel earlier this year said existing eligibility criteria and safeguards in medically assisted dying legislation would be adequate.
Both arguments were made today by a handful of witnesses appearing before the committee, which is deliberating what policies to recommend to lawmakers ahead of the March deadline.
Ellen Cohen, a coordinator advocate for the National Mental Health Inclusion Network, told committee members Canada needs laws to help patients, not hurt them.
“I don’t believe there were any safeguards recommended,” she said.
She resigned from the federal government’s expert panel on MAID and mental illness in December 2021. She said there was no space to identify how vulnerable people could be protected.
The panel released its report May 13, concluding that existing eligibility criteria and safeguards would be adequate “so long as those are interpreted appropriately to take into consideration the specificity of mental disorders.”
Dembo, who was one of the expert panel members, said following those guidelines for people with mental disorders “would ensure an extremely comprehensive, thorough and cautious approach.”
She told the committee people with mental disorders can suffer for decades.
“To say someone with mental illness just shouldn’t be eligible, with that big of a blanket statement, where people don’t even get the chance to be assessed as individuals unique in their circumstances, to me is very stigmatizing,” she said.
While the interim report released earlier this year stops short of making recommendations of its own, it concludes by urging the government to take steps to implement the recommendations of the expert panel “in a timely matter.”
A final report from the committee, complete with recommendations that address other areas including access for mature minors, advance requests, the state of palliative care and the protection of people with disabilities, is due on Oct. 17.
Cohen called the timeline for the legislation to be expanded by March unrealistic.
“I’d like to see this government push this deadline back,” she said.
But Dembo disagreed, telling MPs and senators that assessors are already gaining experience following the existing guidelines.
“Whether or not March 2023 is a realistic deadline depends on how committed and efficient various provincial bodies and local bodies can be in implementing guidelines based on the panel report. I’m hoping they can do that,” she said.
The committee’s review was mandated in the MAID legislation that required that a parliamentary review be initiated five years after the law came into effect in 2016. The committee began its work in 2021 before it was dissolved ahead of the federal election last fall.
The panel and the committee use the terminology “mental disorders,” rather than “mental illness,” stating in their reports that there is no standard definition for the latter and its use could cause confusion.
Conservative MPs on the committee offered a dissenting interim report earlier this year, saying it would be “problematic” to simply endorse the panel’s recommendations.
The MPs argued there are “far too many unanswered questions” on the subject, and nothing precludes the committee from revisiting whether assisted dying should be offered to this category of people at all.
“Legislation of this nature needs to be guided by science, and not ideology,” the Conservatives wrote in May, warning that an outcome that could “facilitate the deaths of Canadians who could have gotten better” would be completely unacceptable.
This report by The Canadian Press was first published Sept. 23, 2022
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