Snake bite first aid tips

Wash the bite with soap and water Immobilize bite area and keep it lower than level of heart Get to medical help as quickly as possible Do not apply a tight tourniquet - this could make it more likely that a limb is lost. If medical help is more than 30 minutes away, tie a loose tourniquet four inches above the bite

In only between nine and 15 cases does the bite prove fatal, but many others are left with permanent damage - it is possible to lose a limb.

However, there is only one supplier of snake serum, known as "antivenin", and production has been suspended since December 1999 after the US Food and Drug Administration launched an investigation into safety at its plant.

The company has been forced to ration supplies ever since.

Now summer has arrived, and more walkers are wandering into wilderness areas home to venomous snakes, many healthcare providers, particularly those in these areas, are expressing concern.

In Joshua Tree National Park in eastern California, the Hi-Desert Medical Center began the summer with 40 vials of antivenin.

Top tips to avoid being bitten by a snake

Leave snakes alone if you see them. Do not try to kill it or inspect more closely Stay out of the tall grass unless you are wearing thick leather boots Do not put hands and feet into areas you cannot see, such as behind logs on the ground Be alert while climbing rocks

Between 15 and 20 are needed to treated the average rattlesnake victim, and following one such case, only 18 vials remain, possibly not enough to treat a patient.

The centre has been forced to contact a naval hospital some distance away to make sure facilities are in place to treat a patient if required - and they have warned visitors to be "extra cautious" when venturing into rattlesnake country.

A spokesman for the FDA told Reuters: "There were manufacturing problems with the plant that led us not to be assured the product was safe."

Rose Ann Soloway, associate director of the American Association of Poison-Control Centres, said: "The issue is not a current shortage, but a potential shortage.

"We don't know how many snake bites will require antivenin."

Snake antivenin manufacture involves injecting a horse with small quantities of the poison, then extracting blood containing antibodies which can fight the poison.

Patients transported to hospital quickly have the best chance of a full recovery.

The American Red Cross recommends that a bite should be washed with soap and water, that it be immobilised, with the wound kept at a level lower than the heart.

Tourniquets or incisions are not recommended, although a loose tourniquet may be needed to slow the progress of the venom if help is far away.

Many venomous snakes will not produce a life-threatening bite, although some species, such as the Eastern diamondback rattlesnake - which can reach six feet in length - will nearly always produce a bit which requires antivenin treatment to prevent death.