PUBLISHED : Sunday, 24 April, 1994, 12:00am
UPDATED : Sunday, 24 April, 1994, 12:00am

DANNY Ledoux's business card is not unlike thousands of others distributed daily throughout Hong Kong. It gives a telephone number and an address, and bears a company logo in English and Chinese. There is nothing out of the ordinary - except the line, in capitals above his name, 'KILLING IS OUR BUSINESS'.

When on the job, Mr Ledoux looks like an identikit version of a professional assassin, wearing an all-black outfit of trousers with the bottoms stuffed into mid-calf lace-up boots, polo neck shirt and a rugged outdoor jacket with lots of capacious pockets; a paramilitary-style uniform that would look at home on the Los Angeles Police Department's SWAT team.

Detailed in his conversation, quietly spoken, and wearing a nondescript pair of trousers and a shirt, Chau Gar-wai is the very opposite of the bustling Mr Ledoux. Yet Mr Chau also kills for a living, or at least he advises on the most efficacious methods of extermination, although as a government civil servant he doesn't advertise the business of killing on his card.

Directly and indirectly, Mr Ledoux and Mr Chau have accounted for the deaths of thousands of one of the world's most intelligent, fastidious, gregarious and adaptable creatures - the rat. As managing director of Pesticide Services of North Point and the Health Department's chief pest control officer respectively, they are at the cutting edge of a battle to control the millions of rodents that swarm the streets, sewers, roofs, and nooks and crannies of Hong Kong.

Rats are not getting a good press at the moment, although as the most cursory glance at a history book will show, they have long been in need of a good PR consultant. In February, 88-year-old Cheung Tai died at Princess Margaret Hospital after she and two other women were attacked by rats in their Tsuen Wan old people's home. Bacterial meningitis was one suspected cause of her death.

Suddenly rats - call them sewer rats, wharf rats, common rats, rattus norvegicus, rattus rattus or bandicots - were again big news. The vice-chairman of the Public Health Committee estimated there was a rat for every one of Hong Kong's six million residents, although Mr Ledoux scoffs at this figure, believing it to be possibly three times higher.

Suddenly the Housing Authority was being blamed by Kwai Tsing District Board member Ting Ying-wah for a plague of rats in the area by failing to maintain hygiene standards and a poisoning programme was started; a week later an 86-year-old man was bitten in his Skek Kong Tsuen home. Suddenly, if media reports were to be believed, Hong Kong was the subject of a plague of rodents of biblical proportions.

Mr Chau works from a Canton Road office overlooking a fetid pool that is the Government's Yau Ma Tei shipyard - around which some of his subjects were doubtlessly sunning themselves as he spoke. The 19 Urban and Regional Council districts each have an individual pest control unit; Mr Chau's job is to offer the knowledge and experience of 27 years as a pest control officer and trained biologist when the district teams come up against something out of the ordinary.

Rats are found everywhere there are human beings and Mr Chau believes that when humanity concentrates in cities, so will rats. The effort put into controlling Hong Kong's rat population is a measure of how great a threat the territory sees the animals to its well-being and self-image.

Characteristically, Mr Ledoux is of the opinion that when rats die and go to rodent heaven, it looks a lot like Hong Kong. As he prepares to lead a six-strong team into the bowels of a Hong Kong Island department store to lay poison, Mr Ledoux says: 'This city is ideal for rats to breed in. They have everything - a good supply of food that is not stored or cleared away properly and lots of places to live in where they cannot be disturbed. Look at those garbage cans - the rats can get into them through the side flaps and live inside. Macau had a terrible rat problem until it changed its methods of waste disposal.' Inside the store the Tannoy is telling shoppers it's closing time. Tonight's job is part of a regular series of preventative visits, although Mr Ledoux ruefully describes how new clients call in pest control companies when they are faced with an infestation - like the Central hotel where diners were interrupted by rats falling into their soup - only to drop the company once the most obvious signs have disappeared.

In the storerooms ringing the shop's substantial food section Mr Ledoux and his men are soon at work spraying for cockroaches, laying down cardboard trays of orange-dyed grain laced with poison, and sprinkling a blue powder that looks like detergent. Both contain anti-coagulants - either the rats eat the grain, or the fastidious creatures lick the blue poison from their fur while grooming. Provided they consume enough they haemorrhage to death; the days of physically trapping and clubbing rodents have gone the way of the Pied Piper of Hamelin.

Poisoning also means one rarely sees dead rats, unless the site is seething with the animals. Mr Ledoux could drop to his stomach and point out with his flashlight rat-chewed food under the freezer and chill cabinets, footprints across the blue powder and plenty of droppings. But of a live and breathing, or dying and bleeding rat there was nothing - not even on a later visit to a factory where rats were said to roam in profusion.

More than 58,000 rat corpses were recovered by government rat catchers last year, but Mr Chau says the number could be up to 10 times higher. 'The anti-coagulant in the poison takes nearly a week to work. The rat does not feel anything, but it gets disorientated, its activity slows and it goes into a coma and dies. Despite the popular misconception, rats do not come out of their colonies and burrows to die; there is a good chance they will die hidden somewhere,' he says, adding they often breathe their last in accessible places like air ducts, pipes and false ceilings.

But rats are smart.

If they only eat enough poison to make them ill, they will not consume it a second time. Pest control experts therefore have to alter the bait between different poisons and are currently using the third generation of anti-coagulants because of the immunity built up by the intended victims.

'I am not sure if we are winning the race against rats,' Mr Chau says, and perhaps with good reason. As he explains, a poisoning job on a block of flats that can kill off up to 80 per cent of the rodents will take up to 10 visits, meaning the rats do not die and decay at the same time. But in case anyone misses the patter of tiny feet behind their skirting boards, he points out that even with such a high kill level, the fact that rats breed so prolifically means you will be back to square one within three months.

The territory's rat population has uncanny similarity to its human one, consisting of the indigenous species and some aggressive interlopers from overseas. Rattus rattus was already living in Hong Kong, foraging in the forest for vegetable matter when the bigger and stronger rattus norvegicus scampered down the gangplanks of ships after the British arrived in 1841. At 350 grams, it weighs a third more than its country cousin and rattus norvegicus has now assumed a dominant numerical ratio of 4:1. Its legs are an equal length, allowing it to run quickly like a horse, whereas rattus rattus has longer hind legs to allow it to climb vertically up pipes, buildings, and regretfully from time to time, up your living room curtains.

Rattus norvegicus is the dirty-brown street-wise rat that skulks in alleyways and chews on the meat and vegetables hawkers and others fail to store at nights; a reporter on a night-time stake-out killed time watching rats chew at a suckling pig stored in an alleyway until it was wheeled in to be the centre piece of a wedding banquet. 'You don't want to mess with those bastards; they fight,' Mr Ledoux says.

Rattus rattus, on the other hand, keeps away from trouble by lurking above floor level, hence its common name of roof rat. Neither species stands a chance against the bandicots, which at 450 grams outweigh even rattus norvegicus by a third. Bandicots live in isolated colonies in the New Territories where they are at the mercy of predatory small mammals, which may account for the failure of rattus norvegicus to spread in rural areas. In urban areas, where 90 per cent of rats live, there are no predators - unless you count Mr Ledoux, Mr Chau and their ilk.

The more run-down districts of Hong Kong such as Shamshuipo, Mongkok, Wan Chai and Yau Ma Tei, with their higher percentage of older and poorly-maintained properties, attract a larger number of rats than places like Mid-Levels. The more working class districts also have more of the open-air markets that form a vast buffet table for hungry rodents. While they may enjoy rooting through garbage for food, rats are not attracted to filth; like the rest of us they prefer to live in a nice and clean setting, and eat good food rather than pick from piles of rotting material.

They want two things, Mr Chau says: food and shelter, and the closely-packed, old-fashioned buildings of Mongkok and similar areas are prime rat real estate.

And one man's rat may be another man's talisman. An old woman living in Western may find a few rats in the house reassuring. It means the household is not poor because there is spare food to feed the four-legged guests. But a householder in Conduit Road, who discovers a rat has been gnawing at the Crabtree and Evelyn soap, will soon be on the telephone to the pest control unit.

However, fears of being overwhelmed by filth and plague bacteria is misleading, says Mr Chau, who points out that mosquitoes transmit far more diseases than rats. It comes down to public relations, since a swarm of mosquitoes is going to be less of a fright than a swarm of rats. 'It is all down to an expression of human feeling,' he says.

Unless they are existing in plague-like proportions rats do not eat huge quantities of food; a rattus norvegicus will consume 30 grams dry weight a day, although it will spoil a lot more than it eats by contaminating food with its droppings. One estimate claims twice as much food is ruined than is actually devoured.

When Mr Ledoux talks about rats he always uses the word 'he' to describe the rodent, as if he is a bounty hunter talking about an escaped renegade on the run. Although he has been bitten more times than he can recall ('it's not too painful' he says manfully), Mr Chau retains a curious affection for an animal he has spent much of his working life killing.

'Do I hate them? No, I don't. They are quite attractive animals. Clean too; they groom themselves all the time. Do you know Walt Disney dreamt up the character of Mickey Mouse by watching a rat's antics? Rodents are very, very intelligent, social animals; very cooperative. They have outsmarted man before and they will outsmart us in the future.' AS A MATTER OF RAT RATFACT: The rat-borne outbreak of bubonic plague known as the Black Death that swept through Europe in the 14th century is estimated to have killed 25 million people.

RATFACT: A rat population density of 1,000 animals per acre was once reported to have infested an Iowa farm.

RATFACT: Rats are prolific breeders with some females reaching sexual maturity within 33 days of birth, although others take three times as long. Litters average between six and eight young, although the size falls away rapidly after the 10th litter.

RATFACT: Actors appearing in the 1970s movie Willard were smeared with peanut butter to make them appear as if they were being 'attacked' by swarming rats.

RATFACT: Rats have skeletons that are so flexible they are able to squeeze through gaps of less than two centimetres; their access is only limited by the dimensions of their skulls.

RATFACT: The two incisors on a rat's upper and lower jaws never cease growing during their lifetime and will grow indefinitely unless the rodent gnaws hard objects. In some animals the teeth spiral outwards like a handlebar moustache, or around and upwards through the lower jaws, eventually locking the snout.