Why does salt remove leeches

They have an anticoagulant in their saliva which stops blood from clotting and makes it easier for them to continue sucking. The first sign of a leech bite may be blood due to this anticoagulant. Leech bites are not dangerous or painful, just annoying. However, if you pull a leech off the wrong way, their mouth can stick under your skin and leave a slowly-healing lump.

Protecting yourself from leeches The easiest way to remove a leech from your body is to prevent one from attaching itself to you in the first place. There are two parts to protecting yourself from leeches: covering up and using insect repellent.

When dealing with land-based leeches, covering your skin provides good protection against leeches. You can even buy leech socks, made from tightly woven fabric to prevent leeches from getting through and attaching themselves. Because leeches are slow eaters, they are pretty careful about finding a nice spot to feed where they won't be disturbed, Kvist says. The ROM exhibit also features live specimens of another bloodsucker with a reputation for going for the groin.

The candiru, which is also known as the toothpick fish or vampire fish of the Amazon River feeds on blood from fish gills, which it locates by homing in on ammonia that the gills expel, Kvist says. Ammonia is also a component of human urine, which may be why doctors have reported the fish being found lodged inside human urethras, he adds. Although he notes this hasn't been verified in the scientific literature. One key feature of bloodsucking animals that can transmit diseases is that they have multiple blood meals over their lives, says Currie.

That includes ticks, which can carry Lyme disease, Rocky Mountain spotted fever, and tick paralysis. If you remove them before that, you're probably fine. That's because they're extremely slow feeders. It takes them weeks or days to complete a blood meal of up to times their body mass.

The other requirement for disease transmission is that the microbes that cause the disease must be able to survive local conditions. This is why salt is so damaging to leeches. What this means is that their skin is made to let moisture easily flow in and out of their body. Remember when I said that salt has the power to draw water out of things? It starts causing all their cells to lose moisture, shrivel up like a raisin, and then die.

If you over-salt your fish pond to try to kill leeches, you could actually burn them and cause tissue damage. And for the record, once full, a leech will drop off itself, and usually in about a half hour.

So if you can stomach it, just wait it out for the cleanest removal. Once the leech is off, clean the bite with water and an antiseptic, dry the area, then clean again, ideally with hydrogen peroxide, which can reduce the effects of the anticoagulant.

If you roughly yank a leech off your skin, you run the risk of causing it to vomit out potentially bacteria-filled blood, as mentioned before. Other common but inadvisable leech removal techniques include burning it with a flame or with the embers of a cigar or cigarette, or dumping salt or vinegar over the animal. In fact, of course, bloodletting is the diametric opposite of what sick people need, but the practice remained common into the 19th century.

Though doctors usually prefer to call it venesection these days.