Drug-resistant strains of the AIDS virus are becoming more prevalent, researchers reported, a development that may warrant pre-treatment screening as well as a renewed emphasis on the need to practise safe sex.

A study of 80 men by the Aaron Diamond AIDS Research Centre at Rockefeller University in New York found that about one in six carried a strain of HIV that was resistant to at least one of a combination of drugs commonly used against the deadly virus. ``We need to explore how widespread this resistance is,''said Daniel Boden, the lead author of the study.

The study, published in this week's journal of the American Medical Association, was the first published that measured drug resistance since patients began taking a daily combination of drugs.

``HIV has a much tougher time resisting three drugs than one,'' Boden said. ``Until we know how much resistance there is and what is causing it, we recommend that infected patients who are able toshould follow the multi-drug therapy.''

The death rate from AIDS dropped 47 per cent in the US between 1996 and 1997 after the multi-drug approach became commonplace.

World time running out for environment, says UN

IT is now too late to halt global warming and time is fast running out to prevent other environmental catastrophes, the UN's environment agency said recently in a major report.

Global Environment Outlook 2000 paints a devastating picture of the earth's health on the eve of the new millennium, and points to new threats, such as increased levels of nitrogen in the water supply, which the world has not yet started to tackle.

``The gains made by better management and technology are still being outpaced by the environmental impacts of population and economic growth. We are on an unsustainable course,'' Klaus Toepfer, head of the UN Environment Programme, said at the African launch of the report here last week. The report says emissions of greenhouse gases that cause global warming havequadrupled since the 1950s, and ``binding'' targets to reduce emissions agreed by governments at last year's Kyoto summit may not be met.

Anti-stress treatment for dogs

A few gentle strokes with the finger-tips along the dog's neck and Border Collie Andy calms down, enjoying the soft massage.

``I stroke the connective tissue in circles, thereby activating the nervous system so that the animal loosens up,'' explains Margret Winkel, who lives in the northern state of Schleswig-Holstein. She is one of about 20 men and women in Germany who are treating pets according to a method developed by the Canadian Linda Tellington. The theory behind it: Our four-legged friends also need help.

``Because there are more and more tensed-up people, the stress is also being projected onto the animals, and they react irritably,'' Winkel says.

Disease kills four Dhaka zoo tigers

Bangladesh's Dhaka zoo has called in vets to fight an infectious disease that has killed four Royal Bengal tigers in the pastmonth, zoo officials said. There were now only 14 Royal Bengals remaining at the zoo, and at least one of them was sick, the officials said.

``The deaths, one after another, have sent an alarm that other tigers may be at risk of dying, too,'' said a zoo official.

A K Munirul Hoq, a veterinary surgeon at the zoo, said:``The tigers were affected by trypanosomiasis, a disease often spread by biting flies. Trypanosomiasis is usually spread by germ-carrying flies... And it may infect other animals as well.''

Consumption of rotten and infected meat might also spread the disease, said a scientific officer at the Central Disease Investigation Laboratory. It is the first time the disease has been diagnosed in Bangladesh. The government asked the zoo authorities to take ``maximum precaution'' in supplying food and maintaining cleanliness in the zoo.

Bangladesh's Wildlife and Nature Conservation Society said in a statement: ``Under the circumstances, we strongly suggest this endangered species should bepreserved in their natural habitat.''