Born: June 27, 1925; Died: November 17, 2014.

WILLY Burgdorfer, who has died from complications of Parkinson's disease aged 89, was a researcher who gained international recognition for discovering the bacteria that causes Lyme disease, a chronic bacterial infection caused by tick bites.

Dr Burgdorfer, who was educated in Switzerland, did his work at the Rocky Mountain Laboratory in Hamilton in the US as a research fellow. He started work at the lab in 1951 and joined the staff as a medical entomologist six years later.

He spent decades researching the connections between animal and human diseases caused by the bites of fleas, ticks and mosquitoes.

In 1982, while he and another researcher were studying deer ticks in the hope of uncovering the cause of a spotted fever outbreak in New York, Dr Burgdorfer found the micro-organisms called spirochetes that would prove to be the cause of Lyme disease.

His previous work on relapsing fever helped him recognise the cause of Lyme disease.

The infection caused children living near Lyme, Connecticut, to develop rheumatoid arthritis.

It also causes heart and neurological problems. The spirochete later was named Borrelia burgdorferi, after Dr Burgdorfer.

In recent years, Lyme disease has become more common in Scotland. Between 2001 and 2010 the number of confirmed cases soared from 28 to 308, though experts believe the true figure could be 10 times that number. Rates are more than three times higher in Scotland than in England.

A colleague and friend of Dr Burgdorfer, Dr Tom Schwan, said the researcher has called his most famous discovery serendipity. It was made while looking for something totally different and is a testament to Burgdorfer's abilities as a scientist, he said.

Dr Burgdorfer's research opened doors to diagnose and treat the disease, Dr Schwan said.

Dr Burgdorfer retired in 1986 after authoring more than 225 scientific papers and travelling the world giving lectures and working with fellow scientists. He won numerous awards, including the Robert Koch Gold Medal for excellence in biomedical sciences in 1988, and received an honorary medical degree from the University of Marseille in France in 1991.

He was born in Basel, Switzerland, and received doctorates in zoology, parasitology and bacteriology. He served in the Swiss Army for three years before moving to the United States, where he became a citizen in 1957.

In 1953, he married Dale See of Hamilton. They had two children William and Carl.

His wife died in 2005 and he later married Lois Rohr, who survives him along with his sons.