Bar staff still fished for tourists coming down the river on tubes, but signs in the town warned visitors about dressing appropriately.

Increasingly, Laotian authorities focused more on the safety of tourists, according to some sources, with improved medical facilities in Vang Vieng and more diligent checks on bars and what they were serving their customers.

Obviously, their ability to monitor the contents and safety of alcoholic beverages still leaves a lot to be desired. But you have to consider this in the context of where Laos sits in terms of development – easily the least advanced of the post-Indochina triumvirate it comprises with Cambodia and Vietnam.

Vang Vieng is an outlier in geographic and social terms. The tourist town is 155 kilometres north of the capital, Vientiane, and about 185 kilometres south of the spiritual hub of Luang Prabang.

However, it is easily accessible from both places by fast, modern and relatively cheap trains on the Laos-China Railway, which began on this line three years ago.

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With about three-quarters of a million residents, Vientiane is as low-energy a city as you will find in this part of the world. Luang Prabang, a UNESCO World Heritage Site with more than 30 significant stupa, or Buddhist temples, is even more laid back.

Vang Vieng has a permanent population of about 25,000 to 30,000, so the annual influx of 900,000 visitors makes it clear what the main industry is. Visitors still go there searching for excitement, but many of the thrills have changed.

Tourism has evolved and there is an increased focus on safer outdoor activities, like guided rock climbing and cave exploration, kayaking tours, hot air ballooning, hiking and cultural visits to local villages.

Better hotels, more diverse cuisine, and game-changing rail links mean the town attracts more families and increasing numbers of Asian tourists, especially from China and Korea.

But there is clearly a hangover from the early days when hedonism ruled, and caution was thrown to the wind. The party may not be over for Vang Vieng and, as the authorities search for the culprits in the latest poisoning cases, travellers still need to view every unidentifiable drink as a potential dive into shallow waters.

Jimmy Thomson is an author and journalist.