Tag: infection

Posted in Psychology & Medicine

Tetanus

Posted on by Jinavie

Tetanus is an infectious disease caused by a soil-borne bacteria called Clostridium tetani. Patients are often infected soil entering the blood through deep wounds, such as a cut. The bacteria produces a toxin called tetanospasmin which leads to the characteristic symptoms of tetanus involving muscle.

The term tetanus actually refers to a state where skeletal muscle remains contracted and cannot relax due to maximum signalling from the nervous system. Tetanus is associated with some distinct symptoms involving tetanised muscles.

Tetanus starts in the face in the form of lockjaw (jaw clamps shut and cannot be opened) and sardonic risus sardonicus. Risus sardonicus, also known as sardonic grin, is a contorted, malicious-looking smile that is caused by spasms of muscles in the face. A good portrayal of the grin is seen in the Joker’s face from the Batman comic book series.
The disease then progresses to cause stiff neck, spasming of chest and leg muscles and difficulty swallowing. 

A dramatic symptom is opisthotonos, where the patient experiences extremely painful contractions of back muscles causing them to arch their back against their will. Along with lockjaw and risus sardonicus, it is a characteristic sign of tetanus and has been known for centuries. Before it was attributed to tetanus, people used to think the person was possessed by a demon due to the agonised screams and involuntary spasming of the body.

The disease is especially devastating in infants and can be spread to the fetus within the womb. This is because babies do not have a developed passive immune system that can combat the infection. Neonatal tetanus carries a mortality rate of over 90% and is responsible for 15% of all neonatal deaths.

Tetanus is a preventable disease through immunisation. Immunisation is done by injecting an inactive form of the toxin (i.e. cannot cause disease), inducing a reaction by the immune system. This essentially “teaches” the immune system to defend the body against tetanus. By completing a course of three doses and receiving occasional booster shots throughout life, tetanus can be prevented. Pregnant women must be immunised against tetanus to prevent neonatal tetanus (the babies receive scheduled immunisations soon after birth too).

This is one example of how immunisation can effectively prevent fatal diseases in a population.

Posted in Psychology & Medicine

Kuru

Posted on by Jinavie

European explorers who visited the island of Papua New Guinea in the 1950’s noticed that the Fore tribe suffered from a strange disease. The patient would initially have headaches, joint pains and tremors. They then show signs of weakness and are unable to stand.  The shaking of limbs, a classic symptom of the disease, becomes progressively worse as the disease progresses (“kuru” is a Fore word for “to shake”). In the late stages, the patient shows other neurological symptoms such as uncontrollable laughter and emotional instability. By this point, their tremors and ataxia (lack of coordination) is so severe that they cannot sit without support. They may also suffer from inability to speak or swallow, become unresponsive to their surroundings, develop ulcers on the skin and become incontinent (cannot hold urine/faeces). Within 3 months to 2 years after the symptoms develop, the patient dies.

Kuru is exclusive to the Fore tribe and medical researchers were puzzled by the nature of this disease. It is incurable and takes more than 10 years to develop (from the time of infection). In 1961, Dr Michael Alpers discovered that kuru was spread due to a certain cultural behaviour within the tribe – cannibalism. The Fore tribe had a tradition of eating the corpse of a deceased tribe member at the funeral as to return their life force back in to the tribe. Of course, this involved the consumption of the brain as well.

It was discovered that kuru is caused by a strange pathogen known as a prion. Prions are misfolded pieces of proteins that cause disease by converting the body’s proteins into “wrong” proteins. These new prions then convert more proteins until the body is filled with deposits of such proteins. Prions mainly affect the brain and cause spongiform encephalopathy – meaning that the brain becomes sponge-like and full of holes. The most famous example of prion disease is mad cow disease.

After colonists took over Papua New Guinea, cannibalism was banned and kuru faded away. This was proof that cannibalism was what spread the prion from one victim to another. It was also discovered that women and children had a higher incidence as men would have priority in choosing what part of the body to eat first. As with lions, the men always chose muscles first and women and children would often finish the organs such as the brain. As prions are indestructible, it cannot be treated, cured or prevented (other than not eating brains). It also means that it transmits perfectly from a dead patient to an unsuspecting victim who is feasting on the infected brain.

A disease that causes the brain to disintegrate, causing limb shaking and inability to walk, spread by the ingestion of brains. Is it possible that zombies are caused by eating brains and not the other way around?

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Posted in Psychology & Medicine

Superbug

Posted on by Jinavie

Frequently on the media, the word “superbug” is used as if it were the new Black Death or the coming apocalypse. What is a superbug and why is it so feared?
Superbug is the colloquial nickname for drug-resistant bacteria. For example, one of the most famous superbugs is MRSA (methicillin-resistant Staphylococcus aureus). This strain S. aureus, a common bacteria found on skin and inside the nose, is resistant to a powerful antibiotic called methicillin and thus very hard to treat. Unfortunately, MRSA is most commonly contracted in hospital settings as patients are vulnerable to infections (e.g. after surgery) and hospitals are perfect breeding grounds for superbugs.

The cause of a “normal” bacteria turning into a superbug is due to the incorrect use of antibiotics. When antibiotics are used, they wipe out a significant portion of the bacterial population but fail to kill all of them in the first attack. The surviving bacteria are the more adapted ones that are able to withstand the harsh environment for a little longer. If the patient stops taking the antibiotics and the bacteria remains, these “drug-resistant” bacteria multiply to create a second infection that is resistant to the drug that was used previously. In fact, this is a classic example of natural selection in motion, except that the environmental change is man-made.
This is the reason why doctors are reluctant to prescribe antibiotics for diseases such as the common cold or viral diseases, as the risk of developing superbugs is greater than the benefit (which is zero in viral diseases as they do nothing) of the treatment. It is also why a course of antibiotics must be finished even if the patient is feeling well, so that even the surviving bacteria are eventually killed.

To show the potential risk of superbugs, the case of VRSA can be taken into consideration. When MRSA was first discovered, doctors found it very difficult to treat but luckily they had a secret weapon – vancomycin, one of the most powerful antibiotics known to mankind. However, they soon found that S. aureus and natural selection easily overcame this through a new strain called VRSA – vancomycin-resistant S. aureus. Here was a bacteria that could overcome the greatest weapon man had against bacteria, all because people were taking more antibiotics than needed and not taking the full course prescribed.

Thus, one of the growing problems of modern medicine is the development of new drugs so that we can make a comeback in the arms race against bacteria.

Posted in Psychology & Medicine

Toxoplasmosis

Posted on by Jinavie

There is a protozoan parasite called Toxoplasma gondii. This parasite infects many animals through an interesting route. 
The first victim is a mouse. An infected mouse loses its fear of cats, leading it to play fearlessly in front of one until it gets caught and eaten (was Jerry a mouse with toxoplasmosis?). It is unclear how it controls a more advanced animal’s brain, but thanks to this effect, Toxoplasma gondii can infect its intermediate host – a cat.
An infected cat starts excreting parasite eggs with its faeces. If a person forgets to wash their hands or eats food contaminated with cat faeces, they can be infected and become the final host for the parasite.

Usually, Toxoplasma gondii cannot overcome the healthy immune system, but it can infect those with a weaker immune system such as the elderly or pregnant women. Furthermore, it is part of the TORCH complex (toxoplasmosis, rubella, cytomegalovirus, herpes) – a group of infections that commonly cross over from the mother to the fetus in utero. Symptoms are normally flu-like, but if more severe it can cause dysfunction of the eyes, brain and other vital organs. Sometimes it lies dormant until the person’s immune system is weakened, whence it becomes active. Toxoplasmosis is also a possible cause of a miscarriage or infertility.

One fascinating symptom of toxoplasmosis is psychiatric disorders. Because Toxoplasma gondii can infiltrate the brain, it is known to cause depression or even schizophrenia. As cats are the most common intermediate host, cat owners are more susceptible to toxoplasmosis. Because of this, there is a theory that “crazy old cat ladies” are in fact toxoplasmosis patients.

Posted in History & Literature

Black Death

Posted on by Jinavie

This disease, also known as Pest or the bubonic plague, was a vicious infectious disease that decimated medieval Europe. It is caused by the bacteria Yersinia pestis, usually transmitted by fleas. The symptoms vary from high fever, malaise, nausea and vomiting, headaches, muscle cramps, seizures, red rashes, coughing and swollen lymph nodes, and causes death within four or five days without treatment.
People did not know about the existence of bacteria back then (it would be 200 more years until Louis Pasteur would suggest germs as the cause of infections). Back then, they considered diseases to transmit through miasma, or bad air. Also, they believed that to prevent transmission, they required a stronger smell to counter it.

Plague doctors, who treated according to the miasma theory of disease, wore a special set of equipments that were known as beak doctor costumes. They wore an overcoat, hat, gloves and boots made from waxed leather, carried a cane to assess the patient and point things out, and a peculiar mask. The mask had a long beak like a bird’s, giving the doctors the nickname beak doctors. The masks had round, glass windows to see through, and two small nostrils at the end of the beak.

Why did they wear this strange mask? The beak was hollow and doctors filled it with flowers, herbs, vinegar and incense that produce a strong smell, so as to “purify” the air coming through the nostrils. 
Although the miasma theory has been falsified by germ theory, this gear was the first hazmat suit in history.

There is another fascinating fact regarding the Plague, miasma theory and beak doctors. It regards the nursery rhyme, Ring a Ring o’ Roses:

Ring-a-ring-a-roses,
A pocket full of posies; 
Atishoo! Atishoo! 
We all fall down. 

This nursery rhyme actually describes the Plague. The ring of roses refers to the red rashes and swelling of lymph nodes – a symptom of the Plague; the posies were herbs used to counter the miasma; coughing and sneezing were end-stage symptoms before death, which is shown in the final line.