NEW YORK (Reuters) — After a life spent on the road and on the rails, U.S. novelist and travel writer Paul Theroux decided to take the world's temperature once again.

In his latest book, "Ghost Train to the Eastern Star," Theroux retraces his steps from an earlier journey across the world that became his 1975 best-seller "The Great Railway Bazaar."

"It's not exactly memory lane, it's not remembering something," Theroux said "It's the literature of revisiting."

Travelling mostly by overnight train, he chronicles his journey through 18 countries including Georgia, Azerbaijan, Sri Lanka, Burma and Cambodia.

"I just thought I'm going to take that trip again and see what it's like, to see how the places have changed," he said. "And of course nothing stays the same."

The nomadic author is stunned but heartened by the transformation of Vietnam since his visit there in the 1970s, in the midst of war.

But Burma, which has since renamed itself Myanmar, strikes him as stagnating in its isolation.

Other places, such as Turkmenistan, were unlike any of the more than 100 countries he has visited and written about.

"Turkmenistan, that was a gift. To go to a place run by a complete lunatic, but a lunatic multibillionaire, is a gift as a traveller," he said, referring to the late president-for-life, Saparmurat Niyazov, known as "Turkmenbashi".

"He's (since) died and it's starting to change now, but I saw it in its moment of greatest madness."

Theroux, who exhibits a caustic wit and powers of observation in the tradition of Mark Twain, found the train station in New Delhi much as Twain had described it, full of travellers and squatters.

While India has changed remarkably since his 1973 visit, Theroux is unimpressed with the transformation of Bangalore — ground zero for the global outsourcing boom.

He describes the once-charming city as clogged and overpopulated and says its call-center workers are "a work force of cultivated coolies."

Such unvarnished views have not endeared him to critics. A New York Times review of "Ghost Train" calls Theroux conceited and says the book is full of "one-line generalisations about places and peoples," many of which are "intellectually intolerable."

Theroux is unapologetic.

"Travel writing has to be truthful. It's a kind of memoir, full of opinions," he said. "It bothers people that it is so personal. It looks self-indulgent, but that's the breaks. It's not a geography book."

Theroux spends much of the year in Hawaii with his wife, where he kayaks on the Pacific and cultivates honey.

Summers are spent on Cape Cod, closer to his hometown of Medford, Massachusetts, visiting family and rooting for the Boston Red Sox baseball team.

After 43 works of mostly fiction and travel writing, Theroux at age 67 shows no sign of slowing down. But don't expect an autobiography.

"When most other writers get to my age, they start looking back and writing memoirs — Kipling wrote his, Greene did — most writers start doing that. It would make me feel old."