It is common understanding in the science world that your genetic information can influence infectious disease. Single base changes in your DNA can influence your likelihood of contracting the disease or the severity of your symptoms. These changes have been studied in diseases such as HIV, hepatitis, malaria, tuberculosis and dengue.
One of the most well studied changes, a deletion of 32 base pairs in a gene called CCR5, is associated with resistance to HIV. The CCR5 gene is involved in the entry of HIV into host cells and when the 32 base pair deletion is present in both copies of the gene, the individual is very unlikely to be infected with HIV, even when coming into contact with it.
So what about coronavirus? Whilst old age and underlying conditions are known, and easily explained, risk factors for coronavirus there are some trends that are currently not possible to explain. Males are more likely to die from the virus than their female counterparts. Some children have developed an inflammatory condition with a fever and skin rash that has been linked to coronavirus exposure and could be potentially life threatening.
It is hoped that the answers to these currently unexplainable risk factors and outcomes will be in our genes. Edinburgh University have teamed up with a number of hospitals, the government and Genomics England to look into the genetics of those that have been admitted to intensive care with the virus. David Bentley from Ilumina, the company involved in sequencing the genome of the virus in the study, has confirmed that the way the virus enters the host cells could be changed by our genes, similar to the changes in HIV entry described above.
Research carried out by Medical Detection Dogs has focused on whether dogs are able to detect different diseases. Pre-pandemic they focused on cancer, neurological diseases and malaria and begun testing various different biomarkers of these diseases in clinical trials.
Medical Detection Dogs have recently partnered with the London School of Hygiene and Tropical Medicine and Durham University to look into whether dogs would be able to detect coronavirus. Professor James Logan at the London School of Hygiene and Tropical Medicine has spoken about his previous work and how dogs can detect malaria with a very high degree of accuracy. He also said that whilst a specific odour for COVID-19 hasn’t been identified yet, other respiratory diseases have been shown to have a specific odour and so there is a strong chance COVID-19 does.
Dogs have previously been able to detect prostate cancer in urine samples and identify individuals with malaria just by smelling their socks! Diabetics are also aware of the super smelling powers of dogs with many using dogs to detect changes in blood sugar levels.
It is hoped that once the dogs are trained, they would be able to detect people infected with the disease quickly, screening up to 250 people in just an hour meaning that our dreams of travelling again could soon be a reality. And if we get to see a cute dog on our airport journey, even better!
Although it sounds like an interesting new boyband, Jumping Frenchmen of Maine is infact a rather extraordinary disorder. First noticed in Maine, in a region near the Moosehead Lake, the disorder is characterised by an extreme reaction to someone startling them. These individuals respond by jumping, screaming, flailing their limbs and even hitting others or throwing objects.
This strange disorder has been thought to occur due to a type of conditioning when a behaviour is learned due to associations with rewards and punishment. However, this condition has been observed in other parts of the USA as well as across the world. In Louisiana it is known as Rajun Cajuns, Latah in Malaysia and Myriachit in Siberia. It has also been observed in India and Somalia, and in Yemen and the Philippines. This suggests that it could be due to a genetic mutation but the disorder is so rare that more individuals would need to be studied to confirm this theory.
Does it win genetic disorder with the weirdest name? It’s certainly a contender.
Measles is a viral disease, caused by the measles virus entering the body, gaining access to your body cells and replicating. It causes a variety of symptoms, the most notable being the high fever and blotchy rash covering the face and neck. Although, since the introduction of the measles vaccine in 1963, the prevalence of measles in the population has decreased dramatically, it still kills over 100,000 people each year (1).
Measles has entered the news again recently due to the surge in cases in the United States. The number of cases this year has been reported as 695 (27thApril) and is expected to rise further.
Los Angeles and the state of California has taken serious precaution by taking 700 students at two Los Angeles universities into quarantine over fears of them contracting the disease. The outbreak is not contained to just California, as 22 states have declared cases. New York have seen the highest number of cases with potentially over 390 cases reported in New York City. The NYC health department have made the controversial decision requiring those in affected areas to get the MMR (measles, mumps and rubella) vaccination or prove they have immunisation (2)
The cause of the outbreak is thought to be linked to a number of anti-vaccination campaigns and children missing out on their suggested vaccinations.
This opens up the question – should vaccines be a legal requirement?
Genetic testing for hereditary diseases is a somewhat controversial technology, developed in the past few decades, which can allow people to ultimately predict their future. For diseases such as Alzheimer’s and Huntington’s this can either be a blessing or a curse.
Huntington’s testing has existed for a few years, as the genetic market for the disease was discovered in the early 1990s and a test for it became commercially available a few years later. This test provides distinct benefits, such as preventing the gene from passing to future generations, and otherwise allowing time for the patient to organise their affairs. However, it also can be a hard idea to come to terms with if the test is positive. People with Huntington’s are four times more likely to commit suicide than the general population.
Alzheimer’s is another disease that has been a recent focus of genetic testing. Dementia affects around 35 million people worldwide, and this figure is likely to triple by 2050. The most common cause of dementia is Alzheimer’s Disease, alongside other types of dementia caused a number of small strokes or irregularities in brain cells. Roughly one in six people over 65 will be diagnosed with Alzheimer’s.
A study by Howard Federoff from Georgetown University, Washington DC, led to the development of the first blood test capable of predicting Alzheimer’s. This tests for ten chemicals, mostly lipids, present in fewer numbers in those with mild cognitive impairment; people who would proceed to get Alzheimer’s. Federoff and his team studied 525 patients that were 70 or older for 5 years, taking blood tests and performing neurological examinations. At the end of the third year, 202 patients remained in the study, of which 53 patients had a mild cognitive impairment or Alzheimer’s and 96 were healthy. The other 53 did not match criteria for either group and so were excluded from the biomarker profiling, which would determine the chemical markers for Alzheimer’s.
Once the ten chemicals had been determined, their functions were investigated and scientists discovered that they help to support cell membranes. A deficiency in these chemicals leads to a decrease in the number of neurons in the brain, potentially triggering Alzheimer’s. The depletion of these chemicals and thus lesser support for the cell membranes can be identified 10-20 years before the onset of the disease, allowing people to predict it’s emergence. As our understanding of the earlier stages of the disease improves – from the findings of studies like these – we move closer to finding new, more effective treatments for this prevalent and debilitating condition. There are currently three trials in action exploring the effectiveness of drugs on different targets identified by studies like these.
A test for Alzheimer’s, as with the test for Huntington’s, presents both advantages and disadvantages. It would allow time to plan for long term care, to inform family members and to organise affairs. Unlike Huntington’s, a genetic and therefore inevitable disease for those with the gene, Alzheimer’s could be delayed or even prevented through diet and exercise. It could also help their family to recognise the symptoms earlier, and allow them to identify them as signs of Alzheimer’s.
The question still remains, however – how much do we really want to know about our own future?
References: Mapstone, M., Cheema, A., Fiandaca, M., Zhong, X., Mhyre, T., MacArthur, L., Hall, W., Fisher, S., Peterson, D., Haley, J., Nazar, M., Rich, S., Berlau, D., Peltz, C., Tan, M., Kawas, C., & Federoff, H. (2014). Plasma phospholipids identify antecedent memory impairment in older adults Nature Medicine, 20 (4), 415-418 DOI: 10.1038/nm.3466
Andrews, L. B. (1999). The Clone Age. New York: Henry Holt and Company.
Hereditary Disease Foudation (2008). Guidelines for genetic testing of Huntington’s disease. Retrieved March 19, 2014, from Hereditary Disease Foundation: www.hdfoundation.org/html/hdsatest.php
Alzheimer’s Society (2014). Demetia 2013: The hidden voice of lonliness. Retrieved March 19, 2014, from Alzheimer’s Society: www.alzheimers.org.uk/infographic
Over one hundred years ago, a man was born that would go on to develop a lifesaving vaccine that saved the lives of millions of children all over the world and although the disease is not eradicated completely, there are only around a thousand cases a year. The polio vaccine, developed by Jonas Salk, was the first ‘killed-vaccine’ where the virus is weakened and then injected and saved millions of lives around the world.
In developed countries these days (before the outbreak of Ebola), the most common disease we have to worry about is the flu but in the first half of the 20thcentury, polio was a worry among parents. In the United States in 1954 alone, there were over 35,000 cases of polio. The virus mainly affected children and epidemics were common every year. Children would have to spend their summer holidays indoor when the virus broke out as parents feared their children would end up in an iron lung (a large metal container that helped polio sufferers with breathing difficulties) or paralysed. Approximately 2,000 children would die every year and another 20,000 would have some form of paralysis.
There are 3 main types of polio: sub-clinical, non-paralytic and paralytic. Sub-clinical polio is the most common (around 95% of cases) and the patient may not even get any symptoms. The virus does not enter the central system. Mild symptoms, if present, include headache, slight fever, vomiting or a sore throat. Non-paralytic is similar to sub-clinical as it is not very severe. It does however, enter the nervous system and produce minor symptoms but does not cause paralysis. These symptoms are normally similar to sub-clinical symptoms but can also include breathing difficulties or back and neck pain. Paralytic polio is the most serious of the three but also the rarest (approximately 1 in every 200 cases). The virus enters the central nervous system and causes paralysis in the patient. It can either cause spinal paralysis or bulbar paralysis which affects the brainstem. In some cases, patients can experience paralysis in both the spine and brainstem. Patients with paralytic polio tend to have a loss of reflexes and muscle spasms and it can lead to deformity of the limbs, most commonly hips, ankles and feet. There is no known cure for polio and all that doctors are able to do is to try and relieve the symptoms. This was a major reason for the push for a vaccine in the 1950’s.
The vaccine was developed by Jonas Salk at the University of Pittsburgh in 1952, but it would take another 3 years of testing before the vaccine was given to the world. The vaccine was developed using monkey cells and killed with a chemical called formaldehyde. The vaccine was one of the first to contain a weakened version of the virus. The development of the polio virus sparked the largest medical trial in history. Over 1.8 million children were involved in the trial which is known as a double blind placebo controlled trial. Around 1.8 million children in America took part with 440,000 children receiving the vaccine, 220,000 receiving a placebo and 1.2 million being observed as a control. The results were announced on the 12th April 1955 and the vaccine was declared safe. In the following years it was then given to millions of children in the United States and worldwide.
Nowadays, there are very few cases of polio around the globe, as it has been wiped out in all but around four countries. With the recent epidemic of Ebola, the fears people had in the 1950’s are coming back and there is a strong need for a vaccine to be developed that can once again save many lives.
Challenger Deep 