Government
The chickenpox virus has a fascinating evolutionary history that continues to affect peoples’ health today
Chickenpox has largely disappeared from the public’s memory thanks to a highly effective vaccine. But the virus’s clever life cycle allows it to reappear in later adulthood in the form of shingles.
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In July 2021, a Centers for Disease Control and Prevention presentation obtained by the press noted that the delta variant of COVID-19 “is as transmissible as chickenpox.”
As some researchers have pointed out, the CDC’s comparison was an overstatement. Based on various studies and projections, on average a person infected with the delta strain of COVID-19 can infect six or seven people, whereas someone infected with chickenpox can infect nine or 10. Nonetheless, both diseases are highly contagious, although the viruses that cause them are very different.
While many diseases, such as Ebola and influenza, originate from viruses that made relatively recent “jumps” from animals to humans, other disease-causing pathogens have been with humans throughout evolution. The virus that causes chickenpox is one of these, coexisting with the human evolutionary line for millions of years.
I am a microbiologist interested in pathogens and the diseases they cause. Chickenpox is a childhood disease, and until a couple of decades ago, nearly all children in the United States got it. A vaccine campaign that began in the 1990s has made the disease rare in children in the U.S., but the virus lingers in the body and can reappear in unvaccinated adults years later as shingles. The virus’s ability to do this disappearing-and-reappearing trick may be the key to its long evolutionary history.
Chickenpox and shingles stem from the same virus
I became painfully aware of the virus that causes chickenpox a few years ago when my husband developed shingles soon after starting a stressful job. Chronic stress is one trigger for reactivation of the dormant virus, as it is for the closely related herpes viruses.
The virus that causes both chickenpox and shingles, varicella-zoster, is only known to infect humans. “Varicella” means “little variola,” or little smallpox, because both diseases cause skin blisters.
Shingles is known in medical terms as herpes zoster. Both “zoster” and “shingles” derive from words for belt or girdle in Greek and Latin, respectively, referring to the typical arrangement of blisters on the torso during shingles outbreaks.
Chickenpox is primarily a childhood disease
Chickenpox is spread by inhalation, and children are infectious a few days before symptoms appear. The blisters also contain live viruses that can become airborne and inhaled or can be transmitted through direct contact. After inhalation, chickenpox viruses invade the cells of the respiratory tract, replicate in the lymph nodes and are spread by white blood cells throughout the body. Eventually, they lodge in the skin, causing the itchy blisters that are characteristic of the disease.
In healthy children, chickenpox lasts about a week and goes away without medical intervention. But it can be more severe in adolescents, adults and people with compromised immune systems. Infection with chickenpox typically provides lifelong immunity to reinfection.
Shingles mostly affects older adults
Even after the chickenpox blisters are gone, the varicella-zoster virus is not. The viruses travel to nerve root clusters located along the spinal cord. There, the viruses establish a persistent, dormant state in the nuclei of the nerve cells.
Over the course of a person’s life, the viruses may reactivate, but usually the immune system eliminates the active viruses before they can appear as shingles. However, as the immune system weakens with age, or as a result of illness or stress, reactivated viruses can travel back along the nerves and erupt again as painful blisters. Typically, only one nerve-root cluster is involved, and the blisters appear in the area of the skin supplied by those nerves. This leads to the classic belt-like appearance, although the blisters can localize to other areas of the skin.
Although even children can develop shingles, the risk of that happening and the severity of the disease increases sharply after the age of 50. The CDC estimates that 1 in 3 people in the U.S. will have shingles at some point in their lives. In healthy adults, a shingles outbreak typically lasts from seven to 10 days; however, about 15% of shingles sufferers develop persistent, often debilitating, neurological pain, called postherpetic neuralgia, that can last for months or even years.
Varicella-zoster has a long, slow evolutionary history
Unlike the COVID-19 and influenza viruses, which have genomes of single-stranded RNA, varicella-zoster’s genome is double-stranded DNA. This makes its genome more stable and able to be copied more accurately than single-stranded RNA genomes.
Although experts disagree on the exact rate at which varicella-zoster accumulates genetic changes, called mutations, a reasonable estimate of its evolution rate is one new mutation every 200 to 400 years. This rate is in contrast to influenza, for example, whose RNA genome is copied so sloppily that it accumulates about 40 new mutations every year, according to my calculations based on data published here.
Varicella-zoster is a member of a large group of viruses, the Herpesviridae, that infect mammals, birds and reptiles. Although there have been some “jumps” between hosts in the distant past, these viruses tend to infect only specific hosts. Thus, scientists can deduce the evolutionary history of the viruses by looking at the known evolutionary relationships of their hosts.
Such analyses indicate that the viruses that eventually led to varicella-zoster and its relatives existed 200 million years ago in the Triassic/Jurassic period – the age of dinosaurs! The closest existing relative to varicella-zoster infects an old-world monkey. The evolutionary lines that led to humans and old-world monkeys split 23 million years ago; thus, our cohabitation with varicella-zoster goes back at least that far.
Recent DNA analysis of varicella-zoster strains currently infecting humans complicates this history somewhat. The data indicates that the virus is accumulating mutations faster than would be consistent with its evolutionary history, and that the ancestor of the current strains appeared only about 8,000 years ago. Such discrepancies between short-term and long-term evolutionary rates have appeared in numerous similar studies, and scientists are currently analyzing why this is so.
The ability to enter a latent state may have given varicella-zoster a survival advantage. Ancient hunter-gatherers would have lived in small groups where an outbreak of chickenpox could have infected the whole population. A credible theory proposed by Charles Grose, a pediatric infectious disease specialist at the University of Iowa, holds that, since chickenpox conveys lifelong immunity, the survivors could not be reinfected. And without new hosts, the virus would die out. However, by persisting for years in survivors in its latent state, varicella-zoster could reappear after a new generation of children was born. Since the shingles blisters are infectious, these children would get chickenpox and a new cycle would begin.
Vaccines for chickenpox and shingles are effective
Prior to 1995, when the chickenpox vaccine was introduced, nearly all U.S. children got infected with chickenpox by age 10. Although usually mild, rare complications resulted in more than 10,000 hospitalizations and 100 deaths per year.
The two-dose vaccine has resulted in greater than 90% protection against infection. Currently the vaccination rate among schoolchildren approaches 95%. By preventing the virus from spreading, this level of vaccination protects unvaccinated children through herd immunity.
The chickenpox vaccine is a live, attenuated varicella-zoster strain that, like the original strain, stays in the body in a dormant state. But the vaccine strain is weakened for activation, and as of 2016 data show that children vaccinated for chickenpox develop shingles less frequently than children did when chickenpox was common. Public health experts do not yet know whether the rate of vaccine-derived shingles will rise as the vaccinated population ages and becomes more susceptible to the disease.
Shingrix, an effective, protein-based vaccine against shingles, has been available since 2017. The CDC recommends everyone over age 50 to get vaccinated for shingles, whether or not they have had chickenpox, shingles or have been vaccinated with Zostavax – a former shingles vaccine that was less effective. Shingrix reduces the incidence of shingles an average of 97% and, if a case occurs, reduces the incidence of postherpetic neuralgia by 91%.
Vaccination requires two doses and is known, so far, to be protective for at least 10 years. As of 2018, 34.5% of U.S. adults 60 and over were vaccinated against shingles, most with Zostavax.
With effective vaccines against both chickenpox and shingles now available, I believe that the countries with high vaccination rates could eventually be free of both of the diseases caused by varicella-zoster – ultimately making the chickenpox-shingles duo go the way of the dinosaurs.
[Get our best science, health and technology stories. Sign up for The Conversation’s science newsletter.]
Patricia L. Foster is affiliated with the Union of Concerned Scientists and Concerned Scientists at Indiana University.
cdc disease control covid-19 vaccine genome genetic rna dna spread deaths herd immunity
Government
Low Iron Levels In Blood Could Trigger Long COVID: Study
Low Iron Levels In Blood Could Trigger Long COVID: Study
Authored by Amie Dahnke via The Epoch Times (emphasis ours),
People with inadequate…
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Authored by Amie Dahnke via The Epoch Times (emphasis ours),
People with inadequate iron levels in their blood due to a COVID-19 infection could be at greater risk of long COVID.
A new study indicates that problems with iron levels in the bloodstream likely trigger chronic inflammation and other conditions associated with the post-COVID phenomenon. The findings, published on March 1 in Nature Immunology, could offer new ways to treat or prevent the condition.
Long COVID Patients Have Low Iron Levels
Researchers at the University of Cambridge pinpointed low iron as a potential link to long-COVID symptoms thanks to a study they initiated shortly after the start of the pandemic. They recruited people who tested positive for the virus to provide blood samples for analysis over a year, which allowed the researchers to look for post-infection changes in the blood. The researchers looked at 214 samples and found that 45 percent of patients reported symptoms of long COVID that lasted between three and 10 months.
In analyzing the blood samples, the research team noticed that people experiencing long COVID had low iron levels, contributing to anemia and low red blood cell production, just two weeks after they were diagnosed with COVID-19. This was true for patients regardless of age, sex, or the initial severity of their infection.
According to one of the study co-authors, the removal of iron from the bloodstream is a natural process and defense mechanism of the body.
But it can jeopardize a person’s recovery.
“When the body has an infection, it responds by removing iron from the bloodstream. This protects us from potentially lethal bacteria that capture the iron in the bloodstream and grow rapidly. It’s an evolutionary response that redistributes iron in the body, and the blood plasma becomes an iron desert,” University of Oxford professor Hal Drakesmith said in a press release. “However, if this goes on for a long time, there is less iron for red blood cells, so oxygen is transported less efficiently affecting metabolism and energy production, and for white blood cells, which need iron to work properly. The protective mechanism ends up becoming a problem.”
The research team believes that consistently low iron levels could explain why individuals with long COVID continue to experience fatigue and difficulty exercising. As such, the researchers suggested iron supplementation to help regulate and prevent the often debilitating symptoms associated with long COVID.
“It isn’t necessarily the case that individuals don’t have enough iron in their body, it’s just that it’s trapped in the wrong place,” Aimee Hanson, a postdoctoral researcher at the University of Cambridge who worked on the study, said in the press release. “What we need is a way to remobilize the iron and pull it back into the bloodstream, where it becomes more useful to the red blood cells.”
The research team pointed out that iron supplementation isn’t always straightforward. Achieving the right level of iron varies from person to person. Too much iron can cause stomach issues, ranging from constipation, nausea, and abdominal pain to gastritis and gastric lesions.
1 in 5 Still Affected by Long COVID
COVID-19 has affected nearly 40 percent of Americans, with one in five of those still suffering from symptoms of long COVID, according to the U.S. Centers for Disease Control and Prevention (CDC). Long COVID is marked by health issues that continue at least four weeks after an individual was initially diagnosed with COVID-19. Symptoms can last for days, weeks, months, or years and may include fatigue, cough or chest pain, headache, brain fog, depression or anxiety, digestive issues, and joint or muscle pain.
Government
Walmart joins Costco in sharing key pricing news
The massive retailers have both shared information that some retailers keep very close to the vest.
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As we head toward a presidential election, the presumed candidates for both parties will look for issues that rally undecided voters.
The economy will be a key issue, with Democrats pointing to job creation and lowering prices while Republicans will cite the layoffs at Big Tech companies, high housing prices, and of course, sticky inflation.
The covid pandemic created a perfect storm for inflation and higher prices. It became harder to get many items because people getting sick slowed down, or even stopped, production at some factories.
Related: Popular mall retailer shuts down abruptly after bankruptcy filing
It was also a period where demand increased while shipping, trucking and delivery systems were all strained or thrown out of whack. The combination led to product shortages and higher prices.
You might have gone to the grocery store and not been able to buy your favorite paper towel brand or find toilet paper at all. That happened partly because of the supply chain and partly due to increased demand, but at the end of the day, it led to higher prices, which some consumers blamed on President Joe Biden's administration.
Biden, of course, was blamed for the price increases, but as inflation has dropped and grocery prices have fallen, few companies have been up front about it. That's probably not a political choice in most cases. Instead, some companies have chosen to lower prices more slowly than they raised them.
However, two major retailers, Walmart (WMT) and Costco, have been very honest about inflation. Walmart Chief Executive Doug McMillon's most recent comments validate what Biden's administration has been saying about the state of the economy. And they contrast with the economic picture being painted by Republicans who support their presumptive nominee, Donald Trump.
Image source: Joe Raedle/Getty Images
Walmart sees lower prices
McMillon does not talk about lower prices to make a political statement. He's communicating with customers and potential customers through the analysts who cover the company's quarterly-earnings calls.
During Walmart's fiscal-fourth-quarter-earnings call, McMillon was clear that prices are going down.
"I'm excited about the omnichannel net promoter score trends the team is driving. Across countries, we continue to see a customer that's resilient but looking for value. As always, we're working hard to deliver that for them, including through our rollbacks on food pricing in Walmart U.S. Those were up significantly in Q4 versus last year, following a big increase in Q3," he said.
He was specific about where the chain has seen prices go down.
"Our general merchandise prices are lower than a year ago and even two years ago in some categories, which means our customers are finding value in areas like apparel and hard lines," he said. "In food, prices are lower than a year ago in places like eggs, apples, and deli snacks, but higher in other places like asparagus and blackberries."
McMillon said that in other areas prices were still up but have been falling.
"Dry grocery and consumables categories like paper goods and cleaning supplies are up mid-single digits versus last year and high teens versus two years ago. Private-brand penetration is up in many of the countries where we operate, including the United States," he said.
Costco sees almost no inflation impact
McMillon avoided the word inflation in his comments. Costco (COST) Chief Financial Officer Richard Galanti, who steps down on March 15, has been very transparent on the topic.
The CFO commented on inflation during his company's fiscal-first-quarter-earnings call.
"Most recently, in the last fourth-quarter discussion, we had estimated that year-over-year inflation was in the 1% to 2% range. Our estimate for the quarter just ended, that inflation was in the 0% to 1% range," he said.
Galanti made clear that inflation (and even deflation) varied by category.
"A bigger deflation in some big and bulky items like furniture sets due to lower freight costs year over year, as well as on things like domestics, bulky lower-priced items, again, where the freight cost is significant. Some deflationary items were as much as 20% to 30% and, again, mostly freight-related," he added.
bankruptcy pandemic trumpGovernment
Walmart has really good news for shoppers (and Joe Biden)
The giant retailer joins Costco in making a statement that has political overtones, even if that’s not the intent.
Share this:
As we head toward a presidential election, the presumed candidates for both parties will look for issues that rally undecided voters.
The economy will be a key issue, with Democrats pointing to job creation and lowering prices while Republicans will cite the layoffs at Big Tech companies, high housing prices, and of course, sticky inflation.
The covid pandemic created a perfect storm for inflation and higher prices. It became harder to get many items because people getting sick slowed down, or even stopped, production at some factories.
Related: Popular mall retailer shuts down abruptly after bankruptcy filing
It was also a period where demand increased while shipping, trucking and delivery systems were all strained or thrown out of whack. The combination led to product shortages and higher prices.
You might have gone to the grocery store and not been able to buy your favorite paper towel brand or find toilet paper at all. That happened partly because of the supply chain and partly due to increased demand, but at the end of the day, it led to higher prices, which some consumers blamed on President Joe Biden's administration.
Biden, of course, was blamed for the price increases, but as inflation has dropped and grocery prices have fallen, few companies have been up front about it. That's probably not a political choice in most cases. Instead, some companies have chosen to lower prices more slowly than they raised them.
However, two major retailers, Walmart (WMT) and Costco, have been very honest about inflation. Walmart Chief Executive Doug McMillon's most recent comments validate what Biden's administration has been saying about the state of the economy. And they contrast with the economic picture being painted by Republicans who support their presumptive nominee, Donald Trump.
Image source: Joe Raedle/Getty Images
Walmart sees lower prices
McMillon does not talk about lower prices to make a political statement. He's communicating with customers and potential customers through the analysts who cover the company's quarterly-earnings calls.
During Walmart's fiscal-fourth-quarter-earnings call, McMillon was clear that prices are going down.
"I'm excited about the omnichannel net promoter score trends the team is driving. Across countries, we continue to see a customer that's resilient but looking for value. As always, we're working hard to deliver that for them, including through our rollbacks on food pricing in Walmart U.S. Those were up significantly in Q4 versus last year, following a big increase in Q3," he said.
He was specific about where the chain has seen prices go down.
"Our general merchandise prices are lower than a year ago and even two years ago in some categories, which means our customers are finding value in areas like apparel and hard lines," he said. "In food, prices are lower than a year ago in places like eggs, apples, and deli snacks, but higher in other places like asparagus and blackberries."
McMillon said that in other areas prices were still up but have been falling.
"Dry grocery and consumables categories like paper goods and cleaning supplies are up mid-single digits versus last year and high teens versus two years ago. Private-brand penetration is up in many of the countries where we operate, including the United States," he said.
Costco sees almost no inflation impact
McMillon avoided the word inflation in his comments. Costco (COST) Chief Financial Officer Richard Galanti, who steps down on March 15, has been very transparent on the topic.
The CFO commented on inflation during his company's fiscal-first-quarter-earnings call.
"Most recently, in the last fourth-quarter discussion, we had estimated that year-over-year inflation was in the 1% to 2% range. Our estimate for the quarter just ended, that inflation was in the 0% to 1% range," he said.
Galanti made clear that inflation (and even deflation) varied by category.
"A bigger deflation in some big and bulky items like furniture sets due to lower freight costs year over year, as well as on things like domestics, bulky lower-priced items, again, where the freight cost is significant. Some deflationary items were as much as 20% to 30% and, again, mostly freight-related," he added.
bankruptcy pandemic trump
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