This is part of our House MD Project series.

Click here to read the connection to the episode (spoiler alert!)


On episode 8 of season 1, called Poison, a student named Matt begins sweating during an AP Calculus exam, and later goes into convulsions. His heart rate is very slow (a symptom called bradycardia). Later another kid named Chi is admitted with the same symptoms. After a lot of trial and error (as is always the case with House), it’s found that both kids bought pants from a guy selling them out of the back of his truck and that a pesticide was spilled on these pants. That pesticide belongs to a type of chemical called organophosphate, which is a rather common cause of poisoning.

The poisoned kid, now cured. Photo by Fox.

Danger level: High

What is it?

Organophosphates are chemicals used widely at home and outside: they exist in insecticides, herbicides, and even in nerve gas. Poisoning with these materials is a dangerous yet common condition.

Who gets it?

In 2007, The American Association of Poison Control Centers’ received 96,307 calls related to pesticide exposures, many of which involved organophosphates. Throughout the world, pesticide poisonings are among the most common poisonings.

No pesticides here. Photo by Transguyjay

What causes it?

Our muscles don’t contract just because they want to. We send them a message to do that, starting in our brain and going down our spine, and finally, through nerves, to the muscle itself. The final connection between the nerve and the muscles is called the neuromuscular junction.

One of the molecules in our body responsible for the action that goes on in the junction is called acetylcholine. This molecule sends a message to the muscle from the nerve, which tells it to contract.

Things get a little (but just a little) complicated when an enzyme (sort of a micro-machine) in the body by the name of acetylcholinesterase breaks acetylcholine down when it’s finished doing its work.

So what do organophosphates have to do with all of this? They inactivate the enzyme, so it can’t break acetylcholine down. This leads to acetylcholine building up and over-working.

How does it feel?

Organophosphate poisoning affects the whole body:

1. Heart – It can cause a slow heart rate (like on the House episode), and low blood pressure.

2. Respiratory system – It can cause a runny nose, can cause spasms in our airways (making it difficult to breath) and also excessive secretions in them, also making it difficult to breath. This all leads to coughing and difficulty breathing.

3. Intestines – Secretions all over our gastrointestinal system (from the mouth to the intestines) can occur. Nausea and vomiting are common, as is also abdominal pain, diarrhea and incontinence.

4. Urine – Incontinence can happen (inability to urinate).

5. Eyes – Organophosphate poisoning can lead to blurred vision and to constricted pupils.

6. Increased sweating.

These are the main effects, but they can be accompanied by brain problems, such as seizures (as was seen in the House episode) and confusion, and also muscle cramping and weakness, along with other symptoms.

How is it discovered?

The poisoning is suspected when someone comes with the group of symptoms described above. Apart from that, a blood test can be done that measures how active the enzyme acetylcholinesterase is.

How is it treated?

Besides helping the poisoned person stay alive (by keeping their airways open, etc.) an antidote is also used. That antidote is usually atropine. What it does is compete with acetylcholine for the spot in the neuromuscular junction, attaching to the muscle before acetylcholine does, so that the effects of acetylcholine subside.

There are other drugs used here which we will not go into at this time.

What happens after treatment?

Usually treating the condition on time should help, although mortality can happen as well (in as much as 25% of cases).

The bottom line – How do I avoid it?

The best prevention is avoidance of contact with chemicals like pesticides. You should take the usual precautions like making sure there’s adequate ventilation when using pesticides indoors, washing all fresh fruit and vegetables before eating, using gloves when working with pesticides, etc.

What next?

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