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DNA Test Identifies Snake Bites

Venom is extracted from a Velvet Killer (Bothrops asper) at Clodomiro Picado Institute in Coronado, Friday June 6, 2003. This particular venom will be transformed into antidote against this snake's deadly bite. The Velvet Killer also known in North America as the Fer de Lance is the most succesful species of venomous snake throughout the Central America region inhabiting from rainforests to cloudforests and to deforested areas where agriculture is the main activity. The Clodomiro Picado Institute is expanding its horizon and exporting antidote to other Central American countries where this snake has the record in bites and deaths per year. (AP PHOTO/MARIANO MATAMOROS)

There may soon be a rapid diagnostic test to determine whether a person was bitten by a venomous snake. There are no reliable numbers on how many people are bitten by snakes each year. One study in 2008 estimated the figure to be at least 420,000 – with up to 94,000 deaths. But experts believe those estimates are probably too low.

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Venomous snakes are common. Researchers say they pose an “especially serious unresolved health threat to millions of people in South and Southeast Asia, Africa and Latin America.”

But there was encouraging news in New Orleans at the annual meeting of the American Society of Tropical Medicine and Hygiene. A DNA test has been developed that takes a swab from the fang marks on people bitten by snakes. Researchers say the test “correctly identified the species of the biting snake 100-percent of the time in a first of its kind clinical study.”

Dr. Ulrich Kuch is with the Institute of Occupational, Social and Environmental Medicine at Goethe University in Frankfurt, Germany -- And part of the research team. He said he wondered if the same type of DNA tests used to catch criminals might be used to identify snakes. Of course, for it to work, you need lots of snake DNA.

“We do need reference material, reference DNA sequences, for each and every species of snake that we deal with – at least for one geographical region or one country where we work. And parallel to collecting samples from bitten patients in hospitals we also need to find the snakes. And we need to take samples from those snakes to get the same genetic information on the particular snakes. So, that’s really biodiversity research meeting clinical research,” he said.

The current test would not be used for rapid diagnosis and treatment. But it is expected to lead to that.

He said, “We use this genetic test as the gold standard in addition to any dead snake brought to the hospital by the patient to determine the species’ identity of the snake involved in the bite. And that is crucial information to inform clinical research in which we validate very rapid diagnostic tests where we compare treatment methods to find out which treatment is better and more cost effective for the patient and the hospital.”

Kuch said that it would be a “dip stick” test similar to a rapid pregnancy test. It could be either a blood or urine test.

“This type of test detects venom. And venom can be detected in the blood of the patient or in urine or from the bite site, as well. Now, we are going for a blood test because snake bite patients when they reach medical care – they have one blood sample taken for clotting tests and some other laboratory examinations. So you can use the blood from the same sample to do this diagnostic test.”

He said it’s far better than what’s happening today in many developing countries.

“Unfortunately, the current method globally is not being treated at all and not seeing any medical help at all. Snake bite and venoming is really one of the most neglected of all tropical diseases, although it causes a huge burden of disease and a very high death toll every year.”

The challenge, he said, is to connect snake bite diagnostics to primary health care in the most affected countries. He says adequate snake bite management is only practiced in a few locations around the world. Kuch describes snake bites as a disease of poverty. Many of those who are bitten are the bread winners of their families. If they do not die from the bite, they may lose a hand or a leg. If they do find treatment, it’s likely to be very expensive.

Kuch said in Africa, for example, snake bites can place a strain on already overburdened health care systems.

“In many of those areas, one out of ten people admitted to [a] hospital is there because of snake bite and venoming. And those are patients who are critically ill, who occupy hospital beds for a long time. They need a lot of attention and that strains health care resources a lot,” he said.

Also, most snake bites occur in rural areas of poor countries, far from urban areas where most health clinics are located. The tests could lead to the stockpiling of anti-venom in strategic locations.