Foreign invaders, be they molds on walls, toxins in polluted air, contaminants in food, viruses, bacteria, parasites, or fungi, represent a threat to our health. Luckily, our body has a way of battling such invaders. A complex network of organs, white blood cells, proteins, and signaling molecules collectively known as the immune system are ready to wage war against the enemy.
The first step is a mobilization of macrophages, a type of white blood cell whose name derives from the Greek for “big eaters”. In a process known as “phagocytosis” macrophages engulf intruders and break them down with enzymes they release from special sacs called lysosomes. If the disease causing organisms (pathogens) prove to be overwhelming, macrophages send out “danger signals” to immune “back-up troops,” most notably two types of T cells. “T” cells originate in the bone marrow but derive their name from the thymus gland in the chest where they mature and learn to distinguish “self” from “non-self.” This prevents “autoimmune reactions” in which the body attacks its own normal components as happens in lupus, rheumatoid arthritis, and multiple sclerosis, all examples of auto-immune disease. When “non-self” needs to be attacked, “killer T cells release cell-destroying “cytotoxins” while “helper T cells” coordinate the attack by sending out chemical messages that attract other immune cells and cause killer T cells to multiply.
Although they are formidable workhorses, T cells can suffer from “T cell exhaustion”. Confrontation with cancer cells is notorious for causing such exhaustion. Fortunately, T cells can recover after each immune mission and take on a new challenge.
After macrophages and T cells have chewed up the invaders, B cells come along and sweep away the debris. As they do this, they identify specific components in the debris that were responsible for triggering immune activity (antigens) and learn to produce special proteins called antibodies that will recognize the antigen should they meet it again. Such an encounter will lead to the destruction of any organism that features the antigen. This is known as acquired immunity.
A question often arises about the possibility of “boosting” our immune system. Since food is the only raw material that enters our body, it stands to reason that all body functions, including our immune system, is affected by what we eat. A diet of whole grains, veggies, fruits, and legumes with minimal alcohol, processed foods and refined carbs goes a long way towards improving overall health, including that of the immune system.
But wait. There is yet another way to boost our immune health. Speed up your lymph circulation! Lymph is the pale-yellow liquid that drains out of blood into surrounding tissues where it is collected and then circulated around the body through lymphatic vessels which are much like blood vessels. This “lymphatic system” also stores “lymphocytes,” such as the T cells and B cells we already encountered, along with “natural killer cells” that specifically attack cancer cells as well as cells infected with a virus.
Eventually, lymph, along with the lymphocytes it contains, is returned back into the bloodstream through lymph nodes, some 600 of which are located throughout the body. Intruders are thus fought both in the lymphatic and blood circulation systems.
Lymph nodes store lymphocytes and also filter cellular waste, viral debris, and damaged cells from lymph. During an infection they have to work harder, which is why they become swollen. Immune cells also grow and multiply in the bone marrow, spleen, tonsils, and thymus gland, all of which are considered to be part of the lymphatic system.
The lymphatic system has no analogue to the heart which is the “pump” that circulates blood and therefore has to rely on the activity of surrounding muscles for circulation. This is where exercise comes into the picture! The more muscular movement, the faster lymph circulates, and the more continuously lymphocytes are delivered to any site in the body where they may be needed, and the more effectively cellular waste is managed. The old adage “you rest, you rust” makes a lot of immunological sense.
Still, as people age, so does our immune system. The thymus, for example, undergoes “thymic involution” meaning that it shrinks with the passage of time. The regression starts at puberty and by the age of 75 or so, the thymus is reduced to merely fatty tissue.
The smaller the thymus, the less its capability to prepare T cells. A shrunken thymus means our T cells dwindle in number as we age and our immune response is less effective. We cannot slow time, but we can slow down immune aging with exercise. You don’t have to run marathons or buy fancy Peloton equipment. A simple after-dinner walk or 30 minutes of pedaling on the old-fashioned stationary bike works just as well.
Beside boosting immune health, exercise also produces endorphins, the body’s natural pain relievers along with dopamine and serotonin, the “happy hormones.” A win-win.
Dr. Nancy Liu-Sullivan holds a Ph.D. in biology and served as a senior research scientist at Memorial Sloan Kettering Cancer Center. She currently teaches biology at the College of Staten Island, City University of New York.
Polio virus found in New York City wastewater, suggesting local transmission – CBC News
Health officials identified the virus that causes polio in New York City’s wastewater, suggesting local transmission of the virus, state authorities said on Friday, urging unvaccinated New Yorkers to get vaccinated.
“The NYC Heath Department and the New York State Department of Health have identified poliovirus in sewage in NYC,
suggesting local transmission of the virus,” the city’s health department said in a statement on Friday.
“Polio can lead to paralysis and even death. We urge unvaccinated New Yorkers to get vaccinated now.”
The identification comes weeks after a case of polio in an adult was made public on July 21 in Rockland County, marking the nation’s first confirmed case in nearly 10 years.
Earlier this month, health officials said the virus was found in wastewater in the New York City suburb a month before health officials there announced the Rockland County case.
The U.S. Centers for Disease Control and Prevention (CDC) said at the time that it was not clear whether the virus was actively spreading in New York or elsewhere in the United States.
Evidence of virus in London
There is no cure for polio, which can cause irreversible paralysis in some cases, but it can be prevented by a vaccine made available in 1955.
New York officials have said they are opening vaccine clinics to help unvaccinated residents get their shots.
Inactivated polio vaccine (IPV) is the only polio vaccine that has been given in the United States since 2000, according to the CDC. It is given by shot in the leg or arm, depending on the patient’s age.
On Wednesday, British health authorities announced they will offer a polio booster dose to children aged one to nine in London, after finding evidence the virus has been spreading in multiple regions of the capital. Britain’s Health Security Agency said polio virus samples were found in sewage water from eight boroughs of London, but there were no confirmed infections.
Polio is often asymptomatic and people can transmit the virus even when they do not appear sick. But it can produce
mild, flu-like symptoms that can take as long as 30 days to appear, officials said.
It can strike at any age but the majority of those affected are children aged three and younger.
Monkeypox: gov’t has no plans to call public health emergency – CTV News
Canada’s chief public health officer Dr. Theresa Tam says there are no plans at the moment to declare monkeypox a public health emergency.
While the World Health Organization and the United States have both recently done so, Tam said there is little benefit to declaring a federal public health emergency in Canada, because of the structure of regional and provincial public health authorities.
She said a federal emergency declaration would involve the Emergencies Act — which hasn’t even been invoked to address the nearly two-and-a-half-year COVID-19 pandemic in Canada. Tam said thus far, Canada has already been able to mobilize vaccines, therapeutics, and funding to tackle monkeypox.
Tam also said local and provincial authorities have more flexibility, and have been able to respond to the rise in monkeypox cases. Local and provincial authorities could also decide to declare the virus a public health emergency at those levels, as many did with COVID-19.
“To date our discussions have focused on testing, working with community organizations to raise awareness on ways to limit spread the virus, and deployment of the Imvamune vaccine and therapeutics,” Tam said. “As the global monkeypox outbreak continues to be a serious concern, focusing efforts on the impacted communities in Canada and worldwide, including with vaccinations, we have an opportunity to contain the spread.”
To day, approximately 99,000 doses of Imvamune have been deployed to the provinces and territories, and more than 50,000 people have been vaccinated, Tam said.
Canada’s Deputy Chief Public Health Officer Dr. Howard Njoo said the approach continues to be vaccinating higher risk communities first, and there are currently enough doses to do so.
Tam says there have been approximately 31,000 cases of monkeypox reported globally, with 1,059 in Canada, mostly in Ontario.
While cases of the virus first started popping up in Quebec, Ontario has since surpassed it in its number of infections.
To date, there have been 28 hospitalizations — two in intensive care — from monkeypox in Canada, and no deaths. Tam said it’s too soon to tell whether the number of cases has plateaued in Canada.
COVID-19 vaccine side-effects less likely in pregnant people, says study – CP24
Pregnant people experienced lower rates of side-effects from the COVID-19 vaccine than their counterparts who weren’t pregnant, a new Canadian study suggests.
The Canadian National Vaccine Safety Network collected data from 191,360 vaccinated women aged 15 to 49 between December 2020 and November 2021. The researchers asked participants to report “significant health events” that were serious enough to make them miss school or work, seek medical attention or disrupt their routines.
Of 5,597 pregnant participants, four per cent reported a significant health event within seven days of receiving their first dose of an mRNA vaccine, and 7.3 per cent of 3,108 pregnant respondents said they had side-effects from their second shots.
Among those who weren’t pregnant, 6.3 per cent of 174,765 respondents reported a significant health event after dose one, and 11.3 per cent of 10,254 participants said they felt sick after dose two.
“One of the things that was really striking was that the rates of these events happening in pregnant people was lower than the rates happening in non-pregnant people at the same age,” said Manish Sadarangani, lead author of the paper published in the Lancet Infectious Diseases journal on Thursday. “It’s very reassuring around the safety of COVID vaccines and pregnancy.”
Studies on other vaccines have found that pregnant people experience side-effects at roughly the same rate as those who aren’t pregnant or even slightly higher, said Sadarangani, an investigator at BC Children’s Hospital.
More research is needed to understand why this might not be the case for mRNA COVID-19 vaccines, Sadarangani said, but he suspects the physical transformation of pregnancy could be a factor.
“There’s a lot of hormonal and immunological and physiological changes happening during pregnancy, and some of them we understand, some of them we don’t,” he said. “I’m presuming that some of these changes are leading to these lower rates.”
Thursday’s study found that rates of serious health events after getting a COVID-19 vaccine, such as hospitalization, were similarly rare across all groups.
There was no significant difference in the rates of miscarriage or stillbirth among participants who were vaccinated and those who weren’t.
Researchers are conducting a followup survey to see if participants experienced any side-effects six months after their COVID-19 shots, Sadarangani said.
Pregnant people are at increased risk of COVID-19 complications, he said, so it’s all the more important that researchers continue to study how vaccination affects them and their babies.
“All of the data we have really highlight the safety of all of these vaccines in pregnancy,” said Sadarangani. “Ultimately, this is the best way to protect this group of people in our population.”
This report by The Canadian Press was first published Aug. 12, 2022.
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