Tuesday 21 February 2017

The spotted history of chicken pox

Most British children will contract chicken pox during their childhood. The disease is almost a rite of passage – the itching, discomfit and, of course, the distinctive rash. Many people have somewhat nostalgic memories of chamomile-soaked days off school, with their equally spotty siblings and an exhausted parent.

Image:Pexels. A child with the typical “head downwards” chicken pox rash
Chicken pox is caused by the varicella zoster virus, one of eight herpes viruses known to infect humans, and is thought to have been infecting humans for millennia. The virus is spread through the air, and can also be spread via contact with the blister on the skin before they heal over. Chicken pox presents as a head-downwards rash, usually very distinctively. In patients aged 1 to 15 years, symptoms, although uncomfortable, are rarely serious.
One in five of those who contract chicken pox as a child will go on to suffer from shingles, known as herpes zoster. This can be made more likely if you are immunocompromised, such as from cases of HIV or cancer, or elderly. Shingles occurs as the varicella zoster virus remains dormant in the body’s nerve tissues where it is repressed by the immune system. Typically a shingles rash will occur in a single painful stripe down one side of the body, following the line of the nerves.
Chicken pox is surprisingly sparsely documented in extreme antiquity. It can be hard to decipher references to diseases in ancient texts, especially when the main symptoms spots – are they describing small pox, herpes, syphilis or just a spot? One approach is to see what the treatments offered were. The more serious the disease, the more extreme the treatment is likely to take, from bloodletting (popular from ancient Greece to the middle ages) to animal dung ointments, noted in the Ebers Papyrus from c 1550 BCE Egypt as having healing properties and working to ward off bad spirits.
Probably the earliest description of chicken pox can be credited an ancient Babylonian text from over 2000 years ago, but the description of a “yoke around the [..] abdomen or pelvis” is more compatible with shingles. The ancient Egyptians suggested treatment of a particular rash with an oatmeal bath, which is still today a popular method of reliving the chicken pox itch.
In the Devi Mahatmya, a Hindu religious text from c 400 CE chicken pox patients should be treated by placing a jar of water at the head of the bed, spreading neem leaves around the doorways of the house and over the bed and all the lamps in the house should be extinguished. Lamp smoke would irritate the rash, causing itching and possible bacterial infection. Neem leaves prevent mosquitoes and the bundles at the doorway would act as a warning to guest that there was disease in the house. The water by the bedside prevents the infected from wandering off to look for a drink. All in all, a very effective treatment and quarantine procedure.
The ancient Greeks identified shingles and called it zoster after word for girdle, as the most common place for the rash to appear is in the peripheral nerves of the back that wrap around the abdomen. Similarly the Romans referred to the disease as cingulus (belt) which is where we get the word “shingles” from.
The source English name “chicken pox” for the childhood rash is more disputed. There are theories that the name arose because the blisters made the skin look like it had been pecked by a chicken or, as proposed by Doctor Samuel Johnson in the 18th century, that is was the coward’s form of Small pox. More likely the name arises from the old English word “giccan” to itch or itchy pox.
In the 1767, the English physician William Heberden demonstrated that chicken pox was not a lesser form of small pox and that a patient who has had chicken pox would remain immune to the disease. It took over a hundred years for another scientist, Rudolf Steiner in 1875, to identify that chicken pox was caused by an infectious agent. He did so by extracting fluid from the blisters of an infected person and rubbing it on the skin of healthy volunteers, they too devolved am itchy, blistering rash.
When Dr. James von Bokay proposed that chicken pox and shingles were, in fact, caused by the same virus he tested the hypothesis by rubbing fluid extracted from shingles blisters into the skin of healthy children. When they contracted chicken pox, it appeared to confirm his suspicions, although it wasn’t until 1953 that Thomas Huckle Weller isolated virus from both illnesses and confirmed that they were, in fact, the same.
Michiaki Takahashi, a Japanese virologist, developed a live attenuated varicella zoster virus vaccine in 1972 and Japan became one of the first countries to routinely vaccinate against chicken pox. The USA followed soon after and cases of chicken pox dropped from approximately 4 million per year to less than 400, 000 in 2005. The vaccine has been adopted into childhood routine immunisations in Canada and Australia and is gaining wider acceptance across Europe.

Image:Pixnio A chicken pox vaccine has been available for decades but has not been made part of NHS childhood vaccination schedules.
The UK has targeted recommendations for the vaccine, such as health care workers, and those with regular contact with immunocompromised persons. By 2005 all NHS works had had their immunity determined and been immunised if they were non-immune.
Whilst chicken pox is rarely fatal, in a pregnant woman the complications can be severe. Risks to the fetus include encephalitis, damage to the development of the eyes, and hypoplasia of the extremities amongst other complications. Newborns who develop symptoms are at a high risk of developing pneumonia and other serious complications of the disease. Meanwhile in the USA vaccine coverage for chicken pox is currently at almost 95% in adolescents aged 13 to 17 years. Over the last year, three and a half million cases of varicella, 9,000 hospitalisations, and 100 deaths are prevented by varicella vaccination in the United States, according to the CDC.
So why does the NHS not currently offer the vaccine to the whole population? There is a worry that, by reducing the numbers of the less harmful childhood chicken pox, there would be a loss of herd immunity for adults. Adults who suffer from chicken pox are much more likely to suffer complications such as pneumonia and the natural boosting of  immunity by expose to the virus by expose to infected children is thought to keep cases of adult chicken pox and shingles down.
In the US, overall rates of herpes zoster (shingles) appears to be increasing, but whether or not this is linked to the increased rate of varicella vaccination is yet to be determined. Many factors can play in to whether or not someone develops shingles, from smoking to obesity to age.
Chicken pox vaccines are still provided on the NHS where there is a clinical need, for example if a child has a sibling or parent with a weakened immune system. Many parents in the UK will make sure their child contracts chicken pox as a child, but if you are worried you do not have immunity, your GP can carry out a blood test to check.
Treatment for chicken pox hasn’t progressed much since the days of neem leaves and oatmeal baths. As long as the young patients can be prevented from scratching the blisters, there will likely be no permeant scarring, the fever will pass and the rash will last only a few days. However some argue that there is no need for this disease at all in modern times and it should go the way of small pox. If we are capable of preventing a disease, should we take those steps to eradicate it?
Adding chicken pox to the MMR vaccine (marketed as the MMRV vaccine) has been proposed in the UK since 2007. However uptake of MMR is far from universal and some parents are still unwilling to vaccinate their children against the more frequently deadly measles, an outbreak of which hospitalized 88 and killed one in Swansea during 2013. No child needs to suffer from a vaccine-preventable disease, from diphtheria to meningococcemia. However chicken pox will remain a childhood “tradition” for a few more generations to come.
Published on Nouse (online) on 21/02/2017

Wednesday 15 February 2017

Treating diabetes mellitus: from ancient Egypt to the NHS

Over the past thousand years of medical progress, mankind has seen a slow but steady increase in human longevity. Though the occasion plague, famine or war will lead to a mortality peak in a generation, by and large each new wave of humanity is healthier than the last.

Image:WikiCommons
But this trend seems to be about to change. A study published in 2015 revealed that middle-aged white Americans are dying at younger ages than their parents for the first time in decades; and as with all trends, where the US leads, the UK and Europe are sure to follow soon after. In fact, there are many  studies suggesting that today's children may lead shorter lives than their parents.

To explain these trends experts have looked to two main factors – firstly “deaths of despair” such as opioid overdoses, suicides and the complications from long term alcohol abuse. In 2015, 52, 000 Americans died of drug overdoses alone, more than died per annum of HIV/AIDS during the epidemic's peak years in the mid 90s. Almost half of these deaths were due to opioid-based drugs, such as heron or the much stronger synthetic opioid fentanyl.

Secondly a more recent study has linked diabetes to the increase in American mortality. Whilst in 1958 only 0.93% of the US population was diagnosed diabetic, now 7.02% (nearly 30 million people) of the country live with the disease. The number has grown three-fold since the early 1990s, rising with the ever increasing obesity rates.  Approximately 368 million people on Earth were living with the disease in 2013.

Most of these cases are  diabetes mellitus Type 2. This is what used to be known as “adult onset diabetes”, to differentiate it from Type 1 diabetes, which involves the auto-immune destruction of the insulin producing beta cells in the pancreas and usually begins in childhood.  Type 2 diabetes now makes up 90% of all diabetes diagnosis  in Europe and is seen increasingly in young adults and children.

Type 2 diabetes is associated with a ten-year reduction in life expectancy, and is though to be an under-reported cause of death, likely affecting life expectancy trends. People with diabetes often have multiple co-morbidities such as obesity, high blood pressure, cardiovascular disease, and even cancer.

Diabetes was one of the first diseases that we can recognise as described in an Egyptian manuscript from c. 1500 BCE. They mention “too great emptying of the urine” and that the urine would attract ants. This is due to the high levels of glucose in the urine seen in untreated diabetics. These first cases are believed to all be Type 1.

Type 1 and type 2 diabetes were described as separate conditions a thousand years later, in India, by the doctors Sushruta and Charaka, with Type 1 being associated with youth and Type 2 with obesity. The name “diabetes” was given by the Greek doctor Apollonius of Memphis in 250 BCE, meaning “to pass through”.

So throughout historical times, both types of the disease were recognised, although rare, and treatments were generally unavailable. Aretaeus of Cappadocia offers a list of symptoms of diabetes, although no treatments and notes “life (with diabetes) is short, disgusting and painful”.

However by the late 19th Century the idea of a low-carbohydrate diet was realised. Whilst under rationing in Paris during the Franco-Prussian war, French physician Bouchardat realised his diabetic patients were faring somewhat better. This lead to some doctors going so far as to keep their patients under lock and key to prevent them from breaking particularly restrictive diets.

In 1889 Germany, Oscar Minkowski and Joesph von Mering removed the pancreas from a dog and saw the poor animal developed diabetes. The protein insulin was eventually identified as being the key to blood sugar control in 1921. Sir Frederick Banting and Charles Best went on to purify insulin from cows and successfully treated a 14 year old boy with Type 1 diabetes in 1922.

Advances were made rapidly, in 1936 the two types of diabetes were made distinct from a treatment perspective and in 1944 a standard insulin syringe was developed. The structure of insulin was first determined in 1951 and first genetically engineered, synthetic human insulin for use in patients was produced using E. coli recombinant expression in 1978.

Since then, there has been huge amounts of progress in the treatment of diabetes, both Type 1 and Type 2, including the introduction of the blood glucose meter and the insulin pump. Short and long-acting insulin derivatives that stem from work done within the York Structural Biology Laboratory at the University of York are now the standard treatment for many Type 1 diabetes patients worldwide.

Researchers at the University of Pennsylvania looked at the prevalence of Type 2 diabetes in the US population and looked at the increased risk of death adults ages 30-84. They calculated that, while diabetes was listed as the cause of death in 3.7% of cases, it was more likely to the underlying cause in almost 12% of the total deaths. Amongst the obese cohort alone, the death rate from diabetes was closer to 19%.

There are now many drug treatments available for Type 2 diabetes, however many have complicated side effects. Most disease management regimens focus on lifestyle interventions to lower various risk factors and maintain a healthy blood sugar level.

Annually, the NHS currently spends £8.8 billion (over 8% of its budget) treating Type 2 diabetes and its complications – from outpatient services to amputations. On a societal level too, Type 2 diabetes has a huge impact on levels of absenteeism and early retirement as the various complications of the disease effect the suffers lives.
Image:Pixabay

Prevention of the onset of Type 2 diabetes is the ideal solution from a healthcare prospective, and it can be achieved with both lifestyle changes and medication. Patients with prediabetes who go through lifestyle changes alone (weight-loss, increased physical activity and quit smoking) can reduce their risk of developing Type 2 diabetes by 50 to 60%.

Although it has been known for some time that obesity and the associated co-morbidities are a leading factor in reduced life expectancy, researchers are hopeful that a focus on diabetes and specifically the control of blood sugar might help healthcare workers and policy makers to combat the trends in mortality statistics. 

An abridged form of this article appeared in Nouse 14/022017

Thursday 2 February 2017

Food, your mood and how we choose

Get short tempered before lunch? Snap at people if you’ve skipped breakfast? Perhaps you are suffering from hanger – the combined effects of hunger and anger.

Self-control requires energy. When our energy levels are low, it follows that our control over our temper is reduced too.

Image:Pexels
As blood glucose levels drop, the stress hormones cortisol and adrenaline are released to drive us to find our next meal. Along with a chemical identified as neuropeptide Y, these combine to make people more aggressive to those around them.

The effects of blood sugar on aggression were measured in a 2014 trial investigating 107 married couples. In the first part, the couples used voodoo dolls and up to 51 pins to express the level of anger that they felt at their partner at that time, and the blood glucose levels of both was measured.

In the second half, the couples played a competitive game, after which the winner could blast the loser with a loud noise through a set of head-phones. As expected, the lower the blood glucose, the more pins and the longer the noise the partners received.

A 2012 study at Columbia University looked at case sentencing by judges and saw they tended to be more lenient first thing in the morning and right after lunch. On the other hand, this may have been more to do with the ordering of the caseload (shorter cases vs longer and more complicated ones) than the timing of meals.

The hunger hormone, ghrelin, which is produced in the stomach prior to meals and during fasting, has been seen to have a negative impact on the brain’s ability to make rational decisions. During an experiment at the University of Gothenburg in 2016, rats with a higher level of ghrelin (mimicking hunger conditions) behaved more impulsively and erratically.

However this study was done in rats, they can be a good model for humans, and more research is needed to confirm the effect is true in us. But perhaps for now be careful when making decisions on an empty stomach.

Wednesday 1 February 2017

Launching a solution to the lithium-ion problem

Image:Flickr
YOU OFTEN find rechargeable lithium-ion batteries in phones, laptops, hoverboards and even planes and electric cars. They are light-weight, highly efficient and rechargeable; this makes them ideal for all sorts of gadgets.
In comparison to nickel-cadmium batteries, lithium-ion batteries are more reliable, hold charge for longer and can be built to be much smaller and thinner.

The components of a lithium-ion battery are much less toxic than those of other battery types, which may contain lead or cadmium. The iron, copper, nickel and cobalt of a lithium-ion battery are safe for landfill or incinerators. Yet, 25 years after their introduction to the market, there are still occasional reports of lithium-ion batteries causing fires in all sorts of devices, including a fire on-board a Boeing 747 flight in 2010 which killed two people.
In 2016 2.5m Samsung Galaxy Note 7 smartphones were recalled due to a problem with their batteries, causing fires and injuries to many users. The recall of the Samsung phones was due to an engineering fault, the theory being that one part inside the battery was coiled incorrectly leading to an excess of stress on another single part. As more demands are made on the battery in any given device, engineers try to pack more power in to smaller spaces.
Within a lithium-ion battery, there are three main components: the positively charged cathode (a metal oxide), the negatively charged anode (graphite) and the liquid electrolyte, a solvent of lithium ions. The cathode and anode must be physically separated by a permeable wall and in very slim batteries this can be done by a polymer as thin as ten microns.If this wall is breached, it can lead to a process called thermal runaway. The battery gets hotter, leading to further degradation of the polymer, which causes the battery to heat even more. The flammable electrolyte can reach 500°C at which point it may ignite or even explode.
Simply adding flame retardant to the electrolyte solution would lessen the chance of fire but at the same time massively reduces the efficiency of the battery. To reduce the risk of a catastrophic fire, researchers at Stanford University have devised an automatic fire extinguisher for lithium-ion batteries. Yi Cui and this team have produced a thin polymer capsule that contains a fire retardant. If the battery overheats to the point that the polymer shell melts, the miniature fire extinguisher is automatically set off and the fire retardant released into the battery.
If these safety devices can be shown to work on a large-scale in a real world setting then it opens lithium-ion batteries to more widespread use in electric cars and aircraft. Currently a safer alternative to lithium-ion batteries is the solid state battery, where the liquid electrolyte is replaced with a solid which is far less flammable. However the inherent problem with the solid state battery is that it takes an incredibly long time to charge – negating most of its useful potential in cars and electronic devices.
Still, it is important to note that lithium-ion batteries are generally extremely safe. The probability of the lithium-ion battery in your phone failing is less than one in a million – whereas the probability of you being stuck by lighting stands at around 1 in 13 000 – meaning that lithium-ion batteries remain a relatively safe and efficient option.

Published Nouse 24 Jan 2017