A Missed Opportunity

In the ICU today, a young girl lies unconscious. Oblivious to the crowd of doctors in the room, she is being kept alive by a ventilator and a feeding tube. She looks very peaceful, as sleeping children often do, but this belies the events going on in her head.
About 14 days ago, she was bitten by a mosquito of the Culex family. Young girls are not normally the target of Culex mosquitoes: they tend to go more for pigs and wading birds, which are the main reservoirs for Japanese Encephalitis Virus (JEV). However, every now and then, humans get bitten. This particular mosquito was carrying JEV and unwittingly transmitted it to our patient. She subsequently developed a fever, headaches and became nauseous. She fitted and then began to lapse into a coma. And now she is in our ICU, fighting for her life.
Only 1% of JEV infections cause encephalitis, accounting for some 50,000 cases annually. Unfortunately though, the outcome when it happens is terrible: 30% die; 30-50% survive, but with irreversible brain damage; and less than 30% make a complete recovery. The only antiviral treatments which exist have been shown to be useless in Japanese encephalitis - all we can do is wait and hope that she is in the minority which pull through.
It is terrible to see a young girl who may well die or be left brain-damaged by a childhood infection. What makes it worse is that Japanese encephalitis is a preventable disease. While the two vaccines offered to travellers are not ideally suited to mass immunisation programmes in the region, a Chinese vaccine has shown great promise. Several trials have shown it to be particularly effective in children, who are the main victims of JEV. Why it has not yet been incorporated into regional vaccination programmes is not clear to me, but it certainly appears to be a missed opportunity.
There are plenty of excellent vaccines out there which have the potential to prevent millions of childhood deaths every year. Most of them are not expensive to produce: the main challenge is making them available to the people who need them, and ensuring that as many people are immunised as possible. At the moment it seems we're investing far more in inventing new treatments than we are in using those that already exist.

Half a Brain

Some people (not scientists) say that we only use half of our brain. While this sounds impressive, I'm not sure what it means - it certainly goes against what I learned in neurology. Nonetheless, it can be surprising to see just how much disruption this soft, watery organ can withstand.
Our patient is a young, HIV-positive man. Like so many of the HIV patients I've seen here, he isn't on any anti-retrovirals. He's come in to the hospital because of three weeks' headaches, which are getting worse. He's also got a fever, and has vomitted on a few occasions. There's no neck stiffness, no lymph nodes and neurologically he's intact. In fact, looking at him, there's very little to suggest anything's wrong. He is well enough to face the ambulance trip across Ho Chi Minh City to the nearest MRI centre: cue sirens and unnecessarily hazardous driving.
As medical students, when reading scans, we're always taught to start by checking the identity of the patient. It would be tempting to assume that the MRI which has just been put up on the light box is of a different patient, but it isn't. The left half of his brain is distorted by a large, ring-enhancing lesion surrounded by oedema. A smaller lesion lies in the occipital lobe. It is hard to believe that this is the brain of the young man who was talking to us earlier and later went out for a walk.

While TB and primary CNS lymphoma are possibilites here, this is toxoplasmosis. The intracellular protozoan parasite Toxoplasma gondii probably infected our patient many years ago, before he had AIDS. His immune system controlled the infection but parasite cysts remained dormant in his muscles and other organs. As a result of HIV, Toxoplasma became reactivated and invaded his brain in dramatic fashion.
About 20% of the world's population has been infected with Toxoplasma, usually as a result of eating under-cooked meat. Our fluffy feline friends are the main hosts for the parasite, innocently fertilising gardens and fields with it. Farm animals then eat it, or we forget to wash our hands, and thus become infected. While most people will experience only a flu-like illness, foetuses can die from toxoplasmosis, which is why pregnant women have to be particularly careful when cooking meat.
As with many parasitic diseases, humans are just an accidental host in the organism's life-cycle, and one which doesn't do it any good. But as our patient demonstrates, such accidents can have devastating effects on vulnerable patients. Fortunately, six weeks' antimicrobials will restore his brain's integrity and he will soon be back to normal. Well, as normal as can be with untreated AIDS.

Twitch, twitch, twitch.

It's International Women's Day today: all the women in the hospital are greeted with a rose and, if they're lucky, a lollipop. I don't recall anyone ever celebrating Women's Day in the UK, but then roses are far more expensive there.
Twitch. In the ICU, one woman is not spending Women's Day as she might have hoped. A few days ago, (twitch), she went to the dentist to have a cavity treated. Somewhere along the way, she became infected with Clostridium tetani, which, as its name suggests, is the bacterium responsible for causing tetanus. Twitch. Painful spasms in the muscles of her jaw brought her to the hospital. Now, after a hefty dose of sedation and muscle relaxants, she is beginning a long and dangerous hospital stay (twitch). She is at very high risk of developing a respiratory infection which, given the frightening rates of antibiotic resistance here, would surely be a death sentence. Despite the doctors' best efforts (twitch), uncontrollable spasms still shake her body every few minutes. You cannot help but look on, waiting for the next one. Twitch. If it wasn't for the sedatives, she would be in agony.

The Clostridium family is a nasty one, responsible as it is for tetanus, gas gangrene and botulism. C. tetani loves a dirty wound and, given the opportunity, will invade in a matter of days. It produces a toxin which specifically targets the central nervous system, impeding the normal mechanisms which regulate muscle contraction. The result is violent muscular spasms, typically starting with the masseters, leading to 'lock-jaw'. The expression risus sardonicus (sardonic smile) is still sometimes used to describe the snarl produced by the disease. (Interestingly, the word 'sardonic' apparently alludes to a Sardinian plant which, when eaten, would produce convulsive laughter and death - so much for herbal medicine). The other characteristic feature of tetanus, the arching of the back or opisthotonus, is more commonly seen in infants than in adults.

Fortunately, tetanus is very preventable. The vaccine probably confers ten years' protection, and it is thought that after three or four jabs there is life-long immunity. In Vietnam, 85% of the population is immunized; however that leaves nearly 13 million unprotected individuals. As the disease does not prevent subsequent re-infection, patients are always followed up with three jabs. Hopefully, with improving vaccine coverage, tetanus will become as rare in Vietnam as it is today in Europe, and patients such as this one will be able to celebrate Women's Day without all the twitching.