To fully appreciate the relevance of Manson and his achievements in China, though, it is necessary to descend into the bowels of Queen Mary Hospital. Here, someone who might be considered a direct successor to Manson works in a cluttered office in the microbiology laboratory.

"I have been an academic for 30 years and have not yet been given an office with a window," jokes Professor Yuen Kwok-yung, chair of infectious diseases at the University of Hong Kong.

Yuen has the rare distinction of being a microbiologist, a surgeon and a physician.

K.Y. Yuen, as he prefers to be called, played a key role in the discovery of the agent that causes Sars and published the first clinical and laboratory diagnostic paper on H5N1, in medical journal . He was honoured as one of magazine's "Asian heroes of the year" in 2003 for helping crack the mystery of Sars and tracing the coronavirus to civets and then to bats.

"I didn't want to be a doctor, I wanted to be an astronaut," says Yuen, an unassuming man with a white coat and a self-deprecating sense of humour. "Then I realised that no non-white people with glasses have ever been astronauts.

"Everyone in Hong Kong should understand who Patrick Manson is," says Yuen, who gives lectures on Manson at HKU and estimates he has spent about a year of his free time visiting London, Scotland, Taiwan and Xiamen, retracing the steps the great man took and researching his life.

in Oldmeldrum, near Aberdeen, Scotland, Manson was not an outstanding student and was apprenticed as an engineer in a local iron works at the age of 15. Curvature of the spine and a tremor in his right arm forced him to choose the alternative career path of medicine, which he studied at the University of Aberdeen.

On graduating, "an urge to travel attacked him", as his biographer (and son-in-law) Philip Manson-Bahr puts it. Manson accepted a job as a medical officer for the China Maritime Customs Service.

On arrival in Kaohsiung, on the west coast of Taiwan, as a 22-year-old newly qualified doctor, he found himself part of a Western community of only 16 people. With few ships to inspect and clinical challenges limited largely to removing leeches from the inside of patients' noses and treating venereal diseases contracted by visiting sailors, he worked at the local missionary hospital, where he started to study the endemic diseases that were a blight on the local population.

Having learned the dialects and developed close local contacts, Manson became entwined in the political struggle between China and Japan for sovereignty of Taiwan and he was advised by the authorities to leave for the port of Xiamen (Amoy) in 1871 for his own safety.

"Amoy at that time was regarded as the white man's grave, highly endemic for malaria, typhoid fever and dengue fever. One in 450 of the population had leprosy," says Yuen.

Based at the small international settlement on Gulangyu Island, off the coast of Xiamen, Manson attached himself to the Baptist Missionary Society Hospital and set about treating local patients, setting up a smallpox vaccination programme, training local medical assistants and researching endemic disease.

"His only research tool was a hand lens. He didn't even have a microscope," says Yuen.

As his reputation grew, Manson started to attract an increasing number of Chinese clients. By 1875, he had 1,980 patients.

Elephantiasis was prevalent in Xiamen at the time.

"There were thousands of hapless Chinese dragging their deformed limbs around the streets, sometimes in danger of being smothered to death by the curse of elephantiasis," writes Manson-Bahr.

In 1877, Manson surgically removed a tonne of elephantiasis tissue from lower limbs and scrotum areas and lost only two patients.

"He was an excellent clinician, brilliant at diagnosis confirmed by post-mortem," says Yuen, although Manson was extremely modest about his own skills in the operating theatre.

"I am a good carpenter but an indifferent surgeon," Manson once told colleagues.

Yuen believes Manson helped to cultivate Chinese acceptance of Western medicine, which was viewed with suspicion in part due to rumours such as that which suggested foreign doctors deliberately created symptoms in people so that they could then treat those patients with success.

Yuen explains that traditional Chinese doctors treated their patients on the street, where everyone could hear the diagnosis and the prescriptions made. That made the whole process transparent.

"Manson understood this psychology and so moved his operating theatre to the ground floor and installed a huge window, where family and friends could clearly witness the anaesthetic surgery and survival of the patient," says Yuen. "Most Western doctors at this time were not working with Chinese patients or were very arrogant and did not try to penetrate those cultural barriers, which is why they were not as successful as Manson, who was a very unusual man."

In 1875, after nine years in China, Manson made an extended trip to Britain, and got married on December 21, 1875. The beautiful Henrietta Isabella Thurburn was 17, he was 31. With his young wife and a compound microscope, he returned to Xiamen to undertake some of his most important research.

Manson embarked on a series of experiments in an attempt to identify the cause of elephantiasis, which he suspected was associated with microfilaria, a tiny embryonic parasitic worm commonly found in the blood of his patients. Using his gardener, Hin Lo - who was infected with microfilaria but not with elephantiasis - as a guinea pig, he allowed mosquitoes to feed on his faithful servant's blood overnight and then examined the engorged insects under a microscope.

"I was gratified to find that, so far from killing the filaria, the digestive juices of the mosquito seemed to have stimulated it to fresh activity," wrote Manson.

Manson had discovered that the female mosquito acts as a nurse to these embryonic parasites and he started to hypothesise about the insect's role in the spread of disease. That the mosquito was the intermediate host of the filarial parasite was a major breakthrough in 1877 and it eventually led to an understanding of how human-to-human transmission occurs. More fundamentally, Manson had established that human diseases could come from animals, an understanding that forms the bedrock of modern public health policy.

That Manson's work was carried out in isolation is difficult to appreciate in our age of limitless online resources.

"I lie in an out of world place away from libraries, out of the run of what is going on, so I do not know very well the value of my work or if it has been done before or better," the doctor wrote in November 1877.

When his findings were presented by his friend, the English scientist Thomas Spencer Cobbold in London, on August 31, 1878, one critic remarked, according to Manson-Bahr, that what they had heard represented the work of a genius or, more likely, the emanations of a drunken Scots doctor in far-off China, where, as everyone knew, they drank too much whisky.

"Nowadays, we all know the mosquito is the vector of many diseases like malaria, Japanese encephalitis, filarial elephantiasis and dengue fever," says Yuen. "We all know to avoid mosquito bites and buy a mosquito net, but this is all due to the work of Patrick Manson."

In 1883, the Mansons and their four children moved to Hong Kong. Manson built a successful private practice on Queen's Road for Europeans and the newly emerging Chinese bourgeoisie. Hong Kong was still considered an unhealthy place by European settlers and the British garrison in the colony was losing between 3 per cent and 13 per cent of its number every year to tropical disease.

"He set up three things which completely changed Hong Kong and China," says Yuen, referring to the Alice Memorial Hospital at 77 Hollywood Road, which Manson founded with Sir Kai Ho Kai; the Hong Kong College of Medicine for Chinese (the forerunner of the current HKU medical faculty), in 1887; and the Medical Society, to facilitate the sharing of research.

It was at the College of Medicine that the father of the modern Chinese republic, Sun Yat-sen, studied and met with the other three of the so-called "four bandits", to plan the overthrow of the Qing dynasty.

"Manson created the fertile soil for this political change and I am very disappointed that so many Hong Kong doctors do not even understand this part of history," says Yuen. "He never forgot his responsibility to the Chinese people. He did not just come here to exploit the Chinese as a colonialist - he did the right thing."

In his inaugural address at City Hall as founding dean of the new medical college, in October 1887, Manson spoke of an opportunity for Hong Kong to be the "centre and distributor not for merchandise only but also for science".

"We have not yet grabbed that opportunity and we are still struggling," says Yuen. "Just look at how little we spend on science compared with the mainland."

Despite this limitation, Yuen's team has identified more than 45 emerging infectious diseases and continues to focus on the discovery of microbes in humans and animals. "I am still doing what I can to find new microbes and new infections; the same as Manson."

Manson made a significant contribution to public health with the founding of Dairy Farm, which provided locals with fresh milk at a reasonable price. Livestock and agricultural staff were introduced from the highlands of Scotland and it was said the locals of Pok Fu Lam, where the farm was located, spoke Cantonese with a faint Scottish accent.

The herd was finally sold in 1983 but the company has grown into a multimillion-dollar retail corporation.

"He realised nutrition was critical in fighting infectious disease and [was concerned about the] lack of a good source of protein. That is what led him to import cows from Scotland and set up Dairy Farm," says Professor Malik Peiris, head of the HKU School of Public Health, in his sixth-floor office on Sassoon Road, not far from where those Ayrshire cows once grazed.

Peiris is another member of Hong Kong's elite group of hugely eminent and honoured medical scientists. A clinical and public health virologist specialising in emerging viruses at the animal-human interface, he played a key role in the discovery of the novel Sars-coronavirus.

"Superficially, of course, there is no similarity between public health now and in Manson's time but at the fundamental level there is in every way," says Peiris. "He was in tune with public fears and irrational responses to health. He realised you must put yourself in the other person's shoes to understand their concerns, however irrational they might be. However confident you might be about the technical aspects, you must communicate that first. To combat an illogical response you can't just confront it, you must try and explain it.

"Manson was the first example of how to do this."

Peiris goes on to explain how important that quality is when rational science is confronted with a public's fear of pandemics such as Ebola, which the World Health Organisation has described as "a public health emergency of international concern".

"The impact of Sars, for example; even though there were about 8,000 patients and about 800 deaths, it affected over 25 countries and the economic cost was estimated to be US$40 billion," says Peiris.

He and Yuen seem relaxed when questioned about the threat of Ebola, despite the alarming media reports.

"In Hong Kong, we don't have a major problem," says Peiris. "If we do have a case, we are well equipped to deal with it. There are 500 isolation beds in place in Hong Kong."

Although both of these eminent scientists are too modest to say so, Hong Kong is recognised internationally as being excellent at investigating and dealing with deadly emerging infectious diseases, 70 per cent of which cross over from animals (as did Sars and Ebola).

On December 10 last year, HKU signed a memorandum of understanding with the London School of Hygiene and Tropical Medicine (LSHTM), the institution founded by Manson in 1899, so that the two organisations could share resources. Manson was a key subject in the speeches and among the 40 distinguished guests at a special ceremony was the director of the LSHTM, Professor Peter Piot, who is credited with co-discovering the Ebola virus.

After some persuasion, Peiris admits that at a high-profile conference in Stockholm in 2009, a highly prominent member of the European Centre for Disease Prevention and Control (who he prefers not to name) told him privately, "The next time we have to deal with a pandemic, we should think about subcontracting the epidemiology of it to Hong Kong."

Though rarely acknowledged or celebrated, Hong Kong is a premier-league player in the international fight against infectious diseases, and Manson is inextricably linked with its glowing reputation. While there is a need for vigilance, it seems that, thanks to this intense Scottish doctor and his colossal legacy, Hongkongers may have less to fear from Ebola than most other major cities.