Archive for the ‘neurotoxins’ Category

Tick-borne disease part two: Tick paralysis & neurotoxins

Monday, April 23rd, 2012

I had almost finished my post on Colorado tick-borne diseases when I noticed an entity I was unfamiliar with, Tick paralysis.  The CDC's comment on this says it's a "loss of muscle function that results from a tick bite." But as I read other websites, it's also the only tick-borne disease that's not caused by an infectious organism, e.g., a bacteria or a virus. Female, egg-laden ticks produce a neurotoxin, a substance poisonous to the normal function of the nervous system.

Typically children under 16, more girls than boys, are affected, and may develop an acceding paralysis, with leg weakness that can rise to the truck within a few hours and potentially cause death.

But if the tick, mostly found on the scalp, is removed, the symptoms usually resolve rapidly.

This particular chemical or mix of chemicals (it's never been identified), is junior league compared to some of its cousins.

choose your sushi chef wisely

The other neurotoxins you may have heard about much more potent. Fugu poisoning  caused by eating a puffer fish/blow fish, was apparently found over 3,000 years ago in ancient Egypt and documented in the 1800s by Captain Cook's journals of exploration. US cases are rare and the fish in question is found off Florida's coast, the Gulf of Mexico and Baja California. But restaurants in Japan and Korea have served it as a delicacy for thousands of years. The chefs who do so go through rigorous training and have to pass both written and hands-on exams before they earn the license to prepare it in a restaurant.

The fish itself can only be offered in grocery store with a permit and, since the toxin, a thousand times as potent as cyanide, is mostly found in the skin, ovaries and liver of the fish, selling them whole is forbidden. There's a great 2009 New York Times article on eating fugu here. I'm not about to try it myself.

It started as a way to catch dinner

And then there's curare, the poison applied to darts in South America which caused paralysis of the muscles used in breathing. It was basically used in hunting as the preparation of this toxic brew (the name actually has been used for a number of substance, mostly made from a poisonous bark) was too laborious for it to be used in fighting other tribes. Eating the flesh of birds or mammals killed by this highly potent mixture has no toxic effect on humans. I'm unaware of any history of hunting using blowguns with curare-tipped darts in the US; instead  curare was used medically, initially in mitigating the seizures that resulted from shock therapy, later in keeping patents immobilized during some surgical procedures. Other drugs eventually were developed to replace it.




Tick paralysis affects cows and sheep, killing thousands, in other segments of the globe. Human cases in the US cases are uncommon and mostly occur in children under 16. Once the tick is removed the symptoms normally  go away rapidly, but rarely severe paralysis can develop before the tick is found and lead to death, Most commonly the tick is embedded in the scalp and two to seven days after it feeds, the child develops weakness in both legs. If nothg is done, the weakness can progress upward and eventually lead to respiratory failure.

Another initial sign of this disease is ataxia, defined on a Mayo Clinic website as a "Lack of muscle coordination during voluntary movements." Tick bites can cause this syndrome without obvious muscle weakness, so be alert if your kids