Good evening all,
As I scan the science news each week, I very often encounter science news reports that are worth sending to you. Some of them are timely matches to our course content, some of them are just plain interesting, and still others are just too important to ignore. This one may fall into the last category.
There is an epidemic of the 'Wuhan coronovirus' in China. And, infected individuals are known to have traveled to a large number of places outside of China, such that infections are now being detected in other countries, including here in the U.S. Worldwide, many thousands are known to be infected, and the number of deaths attributed to this virus, while still low, is rising.
This is a new virus, not seen previously in humans. As viruses go, this one is not especially lethal. But, like may other viruses, it appears to be able to spread reasonable easily from person to person. And, persons infected with the virus can be asymptomatic (e.g., show no outward signs of illness) for some time, allowing them to come into contact with others before they are aware of the need to limit their exposure to others.
Is there a vaccine? No, it is not possible to create a vaccine to a new virus in such short time.
From where has this virus come? It has been suggested to have originated in reptiles (possible snakes), and then made the jump to human hosts. This is not completely novel, as other viruses which cause human disease (such as the HIV virus, or those causing 'swine flu' or 'avian flu') also originated in animals.
Why are humans at risk from these new viruses? Because we have no prior exposure, our medical community has no ready defenses (such as vaccines). Because this virus may be appearing in humans for the first time, our immune systems have not evolved any natural defenses, either.
Should you panic? In short, no. Many more people die because of the seasonal flu virus each year than are likely to suffer death from this one.
What should you do: Most importantly, pay attention to the news, stay informed, and be cognizant of anyone in your circle of interaction who may recently have traveled from an area in China experiencing an outbreak. Only if cases are detected in our community will specific calls to action be issued.
So, if the lethality of the virus is low, and the risk of infection is low, why should you care? It's worth paying attention because this is just the latest in a series of 'new' viruses that have emerged (most in the Asia or the Middle East, including SARS and MERS) that, while of relatively little consequence here, are severely problematic there. Imagine entire cities on lock-down, quarantine. Imagine all of the work, school, and travel that has been disrupted. And, remember, there is still much we do not know about this virus, of its origins, its ability to mutate, and spread.
Ask yourself: what if it happened here? Would our U.S. health agencies be ready and able to combat the emergence of a new virus? Many feel that the answer is 'no'... The best individual defense is information, and awareness - that is why I am sending this along today.
I will occasionally pass along articles of this type during the semester. My purpose in doing so is to help you to become more aware of current physiology and health topics, and also to help you assess how you obtain your science and health news.
Those of us working in science obtain our scientific news, quite often, directly from the original sources: the people conducting the studies and reporting the results. They publish their findings in science journals, or present them at conferences.
Most people do not obtain their science news directly, but hear news via secondary sources, such as news releases from scientific organizations, or as science news stories from the major news outlets. These secondary reports often are then carried by tertiary outlets (smaller/other reporting sources).
Along the way from source to audience, science news is normally distilled (a lot) - much of the detail is excluded or simplified, and the reports often are boiled-down to singular take-home messages, which may, or may not, be good representations of the original work.
When you browse the links that I will forward, or when you access science and health news on your own, I'd encourage you to delve a little bit deeper into them, to read more than just the summaries, and to follow links back to original sources when possible. I'd also encourage you to think a little about the translation of news from source to consumer, and the reputability of the news outlets that you use.
None of these news links that I send you will be represented on our course exams, but I do hope that the material in them makes its way into our physiology conversations. I'm sending this link to both my BIOL 240 lecture and lab sections, so my apologies if you receive this message twice.
This first link is from the New York Times, which provides one of the best (e.g., best funded and most reliable) secondary sources of science and health news. They do limit access to only a handful of free articles each month, so I will use them sparingly.
Have a great rest of the weekend -
Good evening everyone,
At the end of this week we find ourselves in the midst of a discussion of immune function, first with our lecture yesterday on the immune system (Chapter 7), to be followed by our next lecture on infectious disease (Chapter 8), scheduled for next Monday.
Recall that for tomorrow's class (Friday 20 Sept), we will not meet in person. Instead, I'd like you to read/digest a news article on a current and very relevant immune topic, that of environmental exposure to antigens.
For much of the history of our species, human life and society was based around agriculture, including exposure to domesticated animals. In the last hundred years, of course, that has changed for many, as populations became more urban. During this same period, the use of cleansing and sanitizing products in the household has increased dramatically, culminating recently in the explosion of "anti-bacterial" products, such as soaps, wipes, and tissues.
Most immunologists believe that we have taken cleanliness a bit too far. According to the "hygiene hypothesis", natural exposure to antigens keeps the immune system primed for action, and enables it to make robust responses to actual disease agents. In our ultra-clean worlds, however, many (especially the young children of cleaning-obsessed parents) are coming into contact with fewer and fewer natural antigens, and increasingly their immune systems are ill-equipped to respond to them when they do, leading to a rash (no pun intended) of allergies, sensitivities, or, at worst, autoimmune disorders.
This article explores the "hygiene hypothesis" and some of its implications. As you go through it, I'd like you to consider a few key questions:
- what happens to our immune system when we are exposed to naturally-occurring antigens?
- why should exposure to non disease-causing antigens enable us to better respond to more serious antigens?
- do you personally use anti-bacterial products in your household?
- does this article make you want to reconsider their use, in any way?
Our immune system is wonderfully complicated and powerful, but some think that our social behaviors have evolved faster than is good for it. Perhaps a nice walk outdoors, a swim in a lake, or a picnic in the grass is just what we need...
Have a great weekend - see you on Monday.
Good morning all,
As you know, I try to send you an article from the science news each week that is relevant to a recent topic we have considered in our class. Some weeks, that requires a little bit of digging, a little reading beyond my usual outlets for science news. This week, however, there is no need to look far, or wide. Our most recent lecture was on immunity, and the science news has been FULL of stories about the immune system, nearly the entire semester.
This week, there are two major news stories related to immune system function. The first of these is just breaking, and will surely be followed by more news to come: the first widespread use of a vaccine against malaria in Africa. We do not hear much about malaria in this country (even though several thousand cases occur in the U.S. every year), but it is a tropical scourge across much of the globe. It is caused by the malarial parasite Plasmodium falciparum, carried by mosquitoes and transferred between human hosts by their bites. It is very infectious - estimates suggest that more than 200,000,000 (that's 200 million) cases occur each year. It's also very deadly, causing >400,000 deaths per year. Children are especially vulnerable. I heard a news report this week that estimated that every 2 minutes, an African child dies of malaria.
As a disease, malaria is very problematic. Its mosquito hosts are very numerous, widespread, difficult to control, and difficult to avoid. The parasite passes directly into the human host circulatory system during a mosquito blood meal, where it takes up residence inside of red blood cells. Remember that disease agents that get inside of our cells are hard to combat - they are at least partially hidden/protected from immune surveillance, and should they be detected and their host cell destroyed, it results in the net loss of functional host cells, potentially even releasing more parasites to infect other cells. Persons suffering from malaria have symptoms ranging from mild (tiredness, chills, aches) to severe (high fevers, blood clots, kidney damage), and aggressive treatment with anti-parasitic drugs (such as Chloroquine) is normally required. Anti-parasitic drugs can also be used prophylactically (e.g., to prevent infection before it happens), but their efficacy is not perfect and varies considerably against the different strains of the malarial parasite. For all of these reasons, an effective vaccine would be a great benefit.
In the news this week is report of the first widespread use of a moderately-effective, inexpensive, anti-malaria vaccine. It was developed over the last 30 years, following promising laboratory studies (the development of a pharmaceutical, from lab bench to use in human populations, can be VERY long). It is suggested to be only ~30% effective in protecting against malaria. But, if 30% of the hundreds of thousands of deaths that occur each year can be prevented, it will be very worthwhile - imagine being able to create a vaccine that prevents 100,000 deaths each year! In addition, much will be learned from this first really large human trial of the vaccine, and the data that will be collected on its efficacy will likely lead to improvements in the vaccine itself.
The other big story related to immunity this week also relates to infectious disease and immunizations, this time for measles. Measles is a very highly infectious disease caused by the measles virus. It causes rashes, aches, and often dangerously-high fevers, and can be fatal to vulnerable subjects. In most developed parts of the world, measles has largely been eradicated, through successful development and use of the measles vaccine, commonly given as one part of the MMR (measles-mumps-rubella) vaccine. Very recently, however, there are severe outbreaks of measles in several locations in this country (including New York City).
These recent outbreaks in the U.S. have been caused by a combination of two factors. The first is a reduced number of parents having their children vaccinated against measles, in large part due to false information about the potential harm caused by vaccines. Over the past decade, several widely reported (but now discredited) stories have circulated about the use of the preservative thimerosol in vaccines, which has led some to believe that the vaccines themselves are more dangerous than the diseases they are designed to prevent. In addition, the vaccine is so effective that measles is rarely reported, so many believe that it is no longer even necessary. Together, these cause lower rates of vaccination in some populations.
The other causative agent is the introduction of the disease from elsewhere, in these cases from travelers who visited areas in the Middle East, picked-up the virus, and brought it back to their U.S. communities. The symptoms of measles may not appear for weeks after exposure, so persons who carry the virus but do not yet realize it can very easily pass it unknowingly to others.
Vaccinations protect individuals if they encounter an agent of disease, because it primes their immune systems (remember those memory cells?) to make rapid and robust responses upon subsequent exposure to an antigen, such as that of the measles virus. Vaccinations also work at a population level, by reducing the likelihood of encountering a disease in the first place. This is the concept of "herd immunity" - if everyone in a population is vaccinated, the chances of encountering someone who could pass on the disease is very low. Measles is extremely infectious (via sneezing/coughing), such that ~95% vaccination rates are necessary for "herd immunity" against measles to be available. In select populations, immunization rates have fallen well below this level.
This combination of factors (reduced immunization rates, highly infectious virus) leads to disease outbreaks. In addition to large outbreaks in New York and Washington state, several college campus in California began quarantining personnel, in an attempt to control measles outbreaks.
Just as our immune systems are wonderfully adapted to protect us from agents of disease, so too are those same agents of disease evolved to evade our immune defenses. It's an evolutionary 'arms race', and, left on its own, would continue that way. Vaccinations give us a terrific advantage against some infectious diseases - but only if those vaccines are safe, available, and accepted. Are they perfect? Of course not - but the scientific community is very much in agreement that they are better than facing the risks without them. If you hear of anyone near you having measles, make sure that you and your family are protected.
Have a great weekend -
Good morning all,
As we slip slowly into Spring, it's easy to forget that we still are within flu (influenza) season. We should also remember that the latter half of flu season this year is characterized by a more-virulent flu strain than was common during the first half of this year's flu season, which explains why reports of flu-like illness have risen in recent weeks.
Seasonal flu is caused by influenza virus, whose make-up changes from one season to the next as well as over the course of an individual flu season - this is one of the reasons that 'flu shots' (vaccinations against the influenza virus) are recommended every year. Normally, last year's flu vaccine won't protect us this year, and sometimes the vaccine works very poorly altogether.
For most of us, flu is a passing annoyance, but influenza can be deadly - 10,000 people have died from the flu in this country during flu season this year. Last year's flu was particularly deadly, causing 80,000 deaths in the U.S. Most are caused by respiratory failure.
Influenza virus infects our respiratory mucosa (the linings of our respiratory tracts), triggering inflammation and cell death. Much research is aimed at determining how our immune systems detect the virus and attempt to prevent its effects, and new research out this week suggests a surprising tool: taste receptor-like cells, known as tuft cells. They had long been known to exist, but their function was never clear.
This new research shows that tuft cells in our respiratory tract and lungs proliferate and trigger immune responses when virus is detected. Interestingly, they can be promoted across much of the body - including our respiratory tract, out intestines, even our bladder. After infection from flu virus, they appear to remain activated and cause sustained inflammation, which can trigger long-tern allergies and tissue remodeling. Inflammation is a very useful part of our immune function, but it can also provide unnecessary side-effects (allergies, anyone?) and tissue damage if pronounced.
Fortunately, the best defense against the flu is easy: cover your coughs and sneezes, and wash your hands! Otherwise, prepare for your tuft cells to 'Spring' into action (pun intended).
Have a great weekend -