Sick turtles, sick people?

Carol Matroo, Trinidad and Tobago Newsday 20 Apr 08;

A green turtle (Chelonia Mydas) that was found last week and diagnosed with cancerous tumours has raised a red flag of concern for the doctors at the School of Veterinary Medicine (SVM).

While being very cautious with claiming the possible implications of the tumors, the doctors are advising that the tumours may be indicative of the increasing pollution of the environment and may signal a threat to the turtles, and, perhaps ultimately, to human beings.

“We don’t want to be alarmists,” says Professor John Cooper of the SVM. “We are conservationists, but we want to do it in a scientific way. I am not saying this sign on one turtle is a major problem, but we would be foolish not to take notice of it. It’s a bit like smoking and lung cancer 40 years ago. We knew there was a link, but we weren’t really sure. Now we understand it absolutely,” Cooper said.

Cooper said there was no evidence right now that the disease could be transferred to human beings. “We think it’s unlikely. This is almost certainly a turtle cancer, but in this day and age of AIDS and malnourishment, you never know...We just have to assume there is the very, very slight possibility, but I think it is very slight,” he said.

Green turtles are found throughout the world, especially in the tropical and sub-tropical seas, with two distinct populations in the Atlantic and Pacific Oceans. These reptiles, which are considered a delicacy by some, are green because of the fat underneath their shells. It is illegal in most countries to collect, harm or kill these turtles.

Many countries have implemented various laws and ordinances to protect individual turtles and turtle nesting areas. However, the turtle population is still in danger as, in some countries, turtles are still hunted for their flesh and eggs. Pollution indirectly harms the turtles, and many die as a result of being caught in fishermen’s nets where they drown. Now the turtles face a renewed danger from the wart-like cancer known as fibropapillomatosis (FP) which has resurfaced some 70 years since first being reported in the world. The case in Trinidad involves a diseased turtle found at Chaguaramas last month. The turtle is about 30 years old and is said to be the first recorded case of the disease in this country. FP has also been found in Malaysia, the Far East and the United States.

Speaking about the local turtle Prof Cooper said, “When the turtle was found it was obvious it was dying. It was brought to us at Mt Hope. FP is an unpleasant disease, and it does look like warts, but instead of being just simple warts like we might get or cattle might get, these are wart-like tumours, actual cancer.”

He said the cancer is contagious and spreads from one turtle to another and even if a turtle looked fine on the outside, it could be infected on the inside. “It is a malignant tumor that spreads from one place to another. It is a painful disease because the external ones can cause pressure on the eyes so the turtles can’t see properly, on the flippers, on the muscles so the turtle can’t swim properly, so it is a little bit like a rowing boat going around in circles.

“This is a spectacular disease. It’s very distressing for the turtle because it can’t see properly and if the cancer gets inside then it starts to destroy the liver, lungs... it’s like a human cancer. The animal was so thin and filled with fluid inside...it will not die directly of the cancer, but of the weakness.

“They can easily get caught up in fishermen’s nets, or they get killed by someone. It makes them very, very vulnerable to the ocean. We know it’s caused by a virus and the recent thinking is that it has probably been around for millions of years; turtles have been around for 150 million years,” the vet said.

Cooper said it was believed that there had been a good balance between the virus and the turtles, but in recent years, the resistance of the turtles had decreased. He added that there was some indication that more turtles were getting this disease because of pollution of the sea which compromised their immune system.

“If you put on a map of the world everywhere this disease has been reported, a vast majority of them is where there is effluent going out into the sea. You’ll find them along the coast of Florida, California, West Africa, the Far East and places that are close to new developments and factories.” Cooper said more people needed to know and understand this disease because it could be an early warning system.

“We can say it is the chemicals, but as a scientist I have to say that there are more people in those areas, so perhaps the turtles are more frequently spotted, but there has been research work on captive turtles spreading the virus and it has shown that the turtles had been debilitated because they had been exposed to chemicals. We know there have been cases in the Caribbean, but there are no records of them being in Trinidad waters. To be honest, it probably has been here, but people probably haven’t noticed,” he said.

The professor said unlike the leatherback turtles, not much research has been done on the green turtles, which was why the School of Veterinary Medicine was so interested in the latest case.

“This disease has drawn our attention to the fact that we should be monitoring all the turtles on our beaches, not only the leatherback because they are so spectacular,” Cooper said. He said it was found that while other species of turtles could get FP, this did not include the leatherback turtles, which were thought to be possibly resistant to the disease.

“Even that’s important because if the leatherback is resistant, why is it resistant? It could be that it’s got something in its blood or that it’s got immune cells to protect it. By doing our studies we may not only be able to find out why the disease is so bad in the green turtles, but also why the leatherback, which is related, is resistant,” Cooper said.

He said while they were only looking at this one turtle, it nevertheless might be an indicator of pollution here or it might be showing something about the other side of the Atlantic or Africa. “Who knows? We don’t even know where this turtle came from. The way we see it is that the disease has only just resurfaced after 70 years or people are now beginning to notice it.

“What was happening 70 years ago? Industrialization was going on, the Second World War happened, there were ships out in the sea, oil discoveries...We could say, and there is no proof, that this disease is associated with our seas getting more and more polluted, so there may be chemicals in the seas now that are making the turtles less able to resist the virus, and thus easier for the virus to spread,” Cooper said.