Ant venom holds promise as painkiller
DUBAI // A deadly ant that is dominant across the Arabian Peninsula could soon be put to a surprising use as a powerful painkiller.
Scientists in Saudi Arabia believe that venom from the Samsun ant could be harvested and used to make a cheap alternative to anti-inflammatory drugs currently on the market.
The ant species, which is known as Pachycondyla sennaarensis, has been linked with several deaths in the UAE in recent years.
However, zoologists at King Saud University in Riyadh found that the venom could reduce swelling in mice by the same level as diclofenac, a painkiller commonly used to treat chronic conditions such as rheumatism and arthritis.
"This could be a cheaper alternative to other anti-inflammatory drugs," said Abdel-Azeem Abdel-Baki, one of the researchers, whose work was published in the African Journal of Pharmacy and Pharmacology in March last year.
"These ants are very common in the region and the venom can be easily extracted. One day there could be a use for it in medicine."
The researchers injected xylene, an irritant, into the ears of mice. They found that the ant venom could reduce swelling by 33.3 per cent, while diclofenac caused a reduction of only slightly more, 34.8 per cent.
Mr Abdel-Baki said the team were currently experimenting with higher doses but were still some way from human testing.
"We still don't know if it's fit for humans," he said.
The Samsun ant was first identified by entomologists as a tramp or non-native species in the early 1980s, but is believed to have been introduced over a century ago from the humid African savannah regions. As green areas have grown in the region, it has flourished.
"They do very well in grassed, irrigated areas, and that is what we have turned the desert environment into," said Dr Brigitte Howarth, an assistant professor in the department of natural sciences and public health at Zayed University who specialises in desert ecology.
"Because of the way that gardens are spreading across the UAE, the ant is a lot more prevalent as well."
Knowledge of anthropods in the Emirates has been scant until quite recently. Only 14 species of ant were documented until 1994, when foreign researchers managed to record more than 70.
One of those researchers was Barbara Tigar, now a biology lecturer at Liverpool Hope University in the UK. In a 1997 paper, she and her co-authors documented the spread of several introduced species of ant in the UAE - among them the Samsun ant.
"Nice garden environments are also nice environments for species that you wouldn't normally find in the Emirates," she said.
"There's quite a lot of concern about these invasive species of ants. They tend to come in and take over the native species.
"Instead of having quite a wide diversity you just get one species which is dominant, that can really change the whole ecology of an area."
The Samsun ant, which measures four to six millimetres in length, thrives in humid soil conditions and scientists believe it has evolved from a granivorous - grain-eating - diet to become omnivorous as a mechanism to adapt to different environments.
However, it is still regarded as non-aggressive, feeding mostly on seeds, food waste, fruits, small arthropods and dead animals, according to one study of the ants on the Iranian island of Qeshm, by the Tehran-based entomologist Dr Mehdi Sedaghat.
Its colonies range from several dozen ants to several thousand, each with just one queen. The workers are polymorphous, developing into a variety of sizes and shapes according to their role.
Samsun ants have been linked with several deaths over the years, most recently in 2008, when an Egyptian woman in Ras al Khaimah died after an asthmatic reaction brought on by the venom of a Samsun ant.
Although there have been few detailed studies in recent years, pest control experts say Samsun ants are now endemic.
"The number has increased dramatically over the last 30 years," said Dinesh Ramachandran, technical director for the National Pest Control agency. "This poses a serious problem because they are a public health concern. They have a nasty sting and can sometimes kill people."
Mr Ramachandran said nine out of 10 calls to his company for ants turn out to be Samsun ants. However, its sting is only fatal if a person already has a vulnerability to the venom, said Dr Howarth.
"It is only lethal if you are sensitive; if you have anaphylactic reactions to their venom," she said.
"There are only a small number of people who are, but for those people it can be devastating."
She said anyone suspecting they might be allergic should take an allergy test, and if necessary carry an epi pen - a device used to administer injections in cases of severe allergic reactions.
One who learnt her lesson the hard way is Annie Pinnock, a 44-year-old South African dance teacher, who was stung six weeks ago while sitting under a tree in Safa Park.
"I started getting itchy and all of my glands got swollen," she said. "My lips started going numb and I lost hearing. My friends called the ambulance and later I lost consciousness."
Ms Pinnock then went into anaphylactic shock while on her way to Rashid Hospital. "I thought I was going to die," she said.
On arrival she was given an adrenaline shot and within hours she recovered. Now, she carries an epi pen with her in case she is bitten again.
"I had no idea I was allergic," she said.
Tests for determining sensitivity to Samsun ant stings were carried out at Tawam Hospital in Al Ain and published in the October 2006 edition of the Journal of Allergy and Clinical Immunology.
Comparing a group of 31 volunteers who were known to have had anaphylactic reactions to the Samsun venom with a control group of 22 subjects who had minor or no known reactions, allergologists were able to isolate a specific immunoglobulin E (IgE) antibody that determined hypersensitivity.
Skin tests with whole body extract of Samsun ants established that 97 per cent of those who showed a reaction also tested positive for the specific IgE. Among those in the control group who did not have any reaction, 68 per cent tested negative for the antibody.
Vojin Sljivic, a retired microbiologist, co-authored a separate study on reactions to the venom, published in The Lancet in 1992.
"People have different reactions to the ants based on their sensitivity," said Mr Sljivic, who spent a portion of his career in Al Ain and has since retired to London. "That was the basis of our study."
Updated: May 29, 2011 04:00 AM