Here in Hong Kong, estimates range from one rodent for every citizen, according to the government, to two or three times that, according to some private exterminators. We are locked in unwanted symbiosis, their population fluctuating with our hygienic habits.

Thwarting mankind's desire for supremacy, rats cannot be conquered, only contained. Detesting such unscrupulous creatures is a rat race we cannot win. Rats desert sinking ships. They indulge in sex up to 20 times a day - in a single year, about their lifespan, a pair can poduce thousands of offspring. They reassure themselves by leaving constant trails of urine and faeces, that is, when they don't eat it.

Little surprise their role in our vernacular isn't shining . . . smell a rat . . . you dirty rat . . . rat someone out . . . ratbag. Phonetically, ominously, the word gutturally winds up, revs out and snaps like a whip. RRRRAAT. Don't think there aren't companies out there intently focused on building a better mouse trap. (For example, the Trapper Snap Trap, 'carrying technicians into the new millennium better equipped than ever before to control rats', according to United States-based Bell Laboratories.)

Walk our city streets and know that you're within metres of rats - and that's during the day. The city streets double as mass graves, with tens of thousands poisoned carcasses decomposing every year, just below our commuting feet.

On a recent morning in Yau Ma Tei, one of the Government's pest-control teams - there are some 800 employees in all - is engaged in such entombment. C T Ng, uniformed like a boy scout in a shirt with his managerial rank pinned to shoulder straps, checks the day's schedule on his clipboard as his team of three exits an unmarked van. They check some spring-loaded metal cages. Empty. The cuttlefish bait appears unnibbled (Chinese rats don't like cheese, exterminators joke).

Next Ng, displaying his eight years of experience, bends over and checks an imperceptible hole on the sidewalk. He spies droppings and motions for a worker, an elderly woman in hospital-like scrubs, wearing gloves and a surgical mask, to drop bright blue pellets of poison down the holes. Then he tears off a piece of newspaper and carefully lays it over the hole.

The newspaper's role quickly becomes evident when Ng checks another hole, where a piece of paper remains. Apparently, the rat hasn't left its home, the poison having killed it by causing massive internal haemorrhaging, and now Ng's assistant carries over a bucket of mixed concrete and spackles the hole over, a secret sepulchre, the rodent rotting inside.

Offering consolation, Harry Cheung, director of pest-control firm Biocycle, says that because the poison causes significant dehydration, the flesh gives off less smell while decomposing. 'But I can't say there's no smell,' he adds.

Last year the Government trap-ped 55,000 rats but that number, which remains constant, is a fraction compared to those that die of poison, Ng says. The corpses are largely unrecoverable.

Getting a rat to eat rodenticide, an anti-coagulant, requires guile. Suspicious and patient, rats will watch bait for days before consuming it, remember to avoid it if a peer dies, or, most incredibly, employ taste testers. A pack will observe one of their own for days after pressing it into service.

Heading out to a job, the 27-year-old says that for the past two years he's been outwitted and outlasted by rats residing in a $40 million home on the Peak. Glue traps, cages and poison pellets didn't cut it. He's laid white chalk bought from a hardware store on surfaces in attempts to track their point of entry into the home. He's called in a contractor to tear apart wall panelling in search of clues. He's laid poison powder on suspected pathways, explaining that their oily coats wipe away the powder and then they die when they groom themselves. All for naught. 'You can smell them,' he says.'Ugh.'

Three kinds of rats inhabit the SAR. Rattus rattus was living and foraging in the forests when rattus norvegicus scampered down the gangplanks of ships when the British arrived in 1841. Rattus norvegicus, or Norway rats, are the biggest, weighing up to 350 grams - a third more than their indigenous cousin - and stretching to more than 30 centimetres long. Lastly, the house mouse, by comparison, seems cloyingly cute.

Norway rats comprise more than half of the population, says Jackson Chan, president of Hong Kong Pest Control Association, and are commonly found skulking at night around open-air markets and dai pai dongs, especially in the old or run-down districts of Shamshuipo, Mongkok or Wan Chai. Rattus rattus, known as roof rats, have long hind legs, enabling them to climb vertically up drain pipes, buildings, your bedpost.

Wong pulls the car into a driveway overlooking Clear Water Bay, not knowing which rat he's looking for, this being his first house call to the multimillion-dollar home. The amah leads him to the boiler room in the basement where the family located a cage trap, which the quarry evaded. He crawls around and, shining his flashlight, notices a barely discernible stain on the plywood floor. 'Urine.'

Wong checks closets, shelf space, under sinks and then goes outside to look for ways into the basement. Past the pool, putting greens and Buddha busts he discovers water pipes leading into the basement ceiling with tell-tale droppings and bits of black foam - chewed insulation - on the ground.

Wong ventures back inside to interrogate the amah. While preparing meals in the basement, she says, 'I hear a pitter-patter in the ceiling - them playing'. She laughs uneasily. 'Aha,' he says, his suspected entry point perhaps validated. 'You see, I'm right,' he says turning to his partner, Richo Hung Ming.

The amah is encouraged. 'Outside,' she says, holding her hands apart at shoulder width, 'I saw one as big as the car [which happens to be a Rolls Royce Silver Spur]'. Wong lays three poison bait boxes outside the home and will return in a week to check progress. Removing rats from your home typically takes four or so weekly visits.

Wong wraps it up and is on to the next job. Often he works night shifts so that work done in hotels, restaurants and supermarkets goes unwitnessed by the public. Some companies in New York City kit their exterminators in suits and ties as cover. Wong's knowledge could probably single-handedly shutter enterprises. 'Oh, the pests in some of those kitchens,' he grieves. Assuredly, his dining recommendations are as valuable as a Michelin guide's.

Who knows if rats will one day achieve masterdom du monde? With such short life spans, already they have quickly evolved with genetic resistances to the main poison used worldwide. Britain is using a third-generation poison while here in Hong Kong we are still using a second-generation one, says Yuen Ming-chi, officer-in-charge of the pest control advisory section. Yuen says Hong Kong's problem is under control but that 'we still have room for improvement with people dropping refuse on the street'.

Perhaps more apocalyptic, rats are developing behavioural resistances to laid poison, as Jackson Chan, who is also president of the Federation of Asian and Oceanic Pest Managers Association, points to in an industry publication. 'The continued long-term application of a specific control technique that depends for its success upon behavioural patterns is inevitably, in a species as genetically adaptable as a rat, going to select a few individuals that do not behave the way anticipated.' In other words, because of passed-down genes, rats aren't taking the bait.

There are those who have already opted for some form of cohabitation with rats. In Guandong province, they're served in some restaurants, in part according to local lore, to prevent hair from greying. Hindu devotees make pilgrimages to a temple in Rajasthan to bestow sweets, fresh fruit and even bottles of single malt scotch upon the pampered, whiskered residents. Teams of cooks, servants and priests look after the rats, believed to be reincarnated story-tellers of gods.

In the US and the UK, pet rat clubs have formed in recent years, issuing monthly newsletters like Pro-Rat-A. In chat rooms, members console each other after directing invective at pet shops for viewing their beloved friends as only 'snake food'.

A member of Britain's National Fancy Rat Society, Antonia Swierzy, has turned her home into a rattery, allowing her 12 pets free reign. 'I was amazed when I first got rats [eight years ago] how much they loved human company and how quickly they learned things - like when to come when called by name,' says Swierzy, 31, an editor for an international portal Web site living in Cambridge. Swierzy says she looks forward to settling down with a book, with a rat curled up in her sleeve, licking her hand. There's just one thing to which to become accustomed: in a variation of a cat's purr, she says, rats grind their teeth to show happiness - a sound that, in adults at least, is likened to fingernails on a blackboard.

Additional reporting by Vivienne Chow

Rat Facts

Diet: omnivorous, including dead and dying members of their own species. Feed 15 to 20 times a day.

Reproduction: Prolific breeders at two months; can have litters as often as every 40 days, with four to seven young per litter.

Carrier of diseases: Plague and hanta virus. Plague is spread by fleas on rats. It was the source of the Black Death in 15th-century Europe, which killed millions of people. Plague is still common in India. The fatal hanta virus is present in rats' urine and faeces. Humans can become infected when exposed to contaminated dust from the nests or droppings of mice. Initial symptoms are fever, headache, nausea and vomiting. Progression is rapid. The patient bleeds internally and ultimately develops respiratory failure.

Signs of rat activity: gnawing on plastic, wood or rubber materials; damaged, partially eaten fruit (the two incisors on a rat's upper and lower jaw never cease growing in their lifetime, hence their need to gnaw). Greasy rub marks caused by rats' oily fur coming into contact with surfaces. Scattered droppings, dark in colour, pellet-shaped, about one-centimetre long - a couple can produce 18,000 faecal droppings in six months.

What you can do to keep them out: Make sure all gaps are sealed. Keep doors and windows shut so they can't get in. Keep your home clean. Remove possible food sources for rats and always place garbage in bins.

What you can do if they get in:

Find out where they hide. If they are

in your kitchen, isolate them by keeping the kitchen door and windows

shut. Place glue traps, available from hardware stores and pest control

companies for around $20 per pair,

in corners as rats tend to crawl along the edges of rooms. It may take an hour or a whole day for the offenders to surface - they're very patient. Rat bait is best left to the professionals. Call the Government's Pest Control Information Unit on 2867 5209.