Deadly spiders found in Death Railway cave

Samples of the tiny but highly venomous Mediterranean recluse spiders are shown with a one-baht coin for comparison at a Chulalongkorn University Science Department press conference on Wednesday. (Photo by Patipat Janthong)

Tourists and avid cavers are being warned of dangerously poisonous Mediterranean recluse spiders which have been discovered in Thailand for the first time in Kanchanaburi province.

The brownish yellow spider measuring about 7 by 7.5 millimetres can cause severe wound infections and even kill a person, if bitten, though there have so far only been a small number of such extreme cases worldwide, Narin Chomphuphuang, a doctoral student at Chulalongkorn University's (CU) Faculty of Science Biology Department, said yesterday.

Mr Narin issued the warning after he found the arachnid species by chance when he explored a cave in Sai Yok district.

He estimated there are up to 500 spiders in the cave, which was once used for the storage of construction materials by Japanese troops building a rail route across the Kwae Yai River during World War II.

Mr Narin believed the Mediterranean recluse spiders came to Thailand during World War II, saying it is possible the spiders were "stowaways" in ships transporting construction materials from Japan to Thailand during the railway's construction.

"Their numbers seem to be limited to just one cave," Mr Narin said, adding he has not found any in five other nearby caves.

Japan, along with China, Taiwan and Korea, are among Asian countries where Mediterranean recluse spiders have been found besides discoveries in, for example, Australia, the United States, Mexico, Brazil and European countries.

Their appearance in Kanchanaburi is a first because "there have never been reports of sightings in Thailand and Southeast Asia", said CU biologist Nathaphot Warit.

While the original habitat of the spiders is in Mediterranean countries, increased trade links and travel has resulted in the spiders being found living and multiplying elsewhere.

The spider, known scientifically as Loxosceles rufescens, has also earned the nickname "violin spider" because of a dark brown marking on its body which resembles a violin.

As suggested by its common name, a Mediterranean recluse spider is not aggressive and tends to hide.

Only a few fatalities from the spider's bite have been reported globally.

Chula scientists showed these photos of severely infected wounds caused by a Mediterranean recluse spider bite, and its habitats. (Photos courtesy of Chulalongkorn University's Faculty of Science.)

EARLIER REPORT

Deadly Mediterranean recluse spiders have been found for the first time in Thailand in a cave in Kanchanaburi used for storage during the building of the infamous Death Railway.

They were discovered by doctoral student Narin Chompupang, and it was announced at a media conference at the Chulalongkorn University faculty of science in Bangkok on Wednesday.

Mr Narin, a biology student, came across them during a survey of the cave at the site of the royally sponsored Plant Genetic Conservation Project on Khao Wang Khamen mountain in Sai Yok district of Kanchanaburi province.

The Mediterranean recluse spider is either yellow or brown, and about seven miilimetres long. The spider’s toxic venom eats into any flesh it comes into contact with, leading to nasty and painful lesions that can take several months to heal.

It is regarded as among the most venomous spiders in the world and is now found in many countries including Australia, China, many European nations, Japan, Korea, Mexico, Russia, Taiwan and the United States, Mr Narin said.

He found the spiders in only one cave. He speculated they had arrived during World War II, hidden in railway materials brought from Japan, because that cave had been used for storage during construction of the Death Railway.

He estimated there were about 500 Mediterranean recluse spiders in the colony in the unidentified cave.

Natthapoj Warit, a biology lecturer, said a bite from the highly poisonous spider looked like a mosquito or ant bite. Unless it was treated by a doctor, the wound could become infected in a few days. In some cases overseas it had proved fatal for people who were not treated.

The Mediterranean recluse spider is the third species of extremely poisonous spiders found in Thailand, along with two kinds of widow spiders, Mr Narin said.