On the list of urban nuisances, rats rank somewhere below high rents and above loud neighbours. This summer, though, they seem determined to make it to the top of the list. Rat attacks have sent three people to hospital in the past two months alone. In Happy Valley, rats were seen scurrying across a children’s playground in broad daylight. Rats have even descended on squeaky-clean Discovery Bay, where residents have reported an infestation in the main plaza and along the shoreline, where rats were seen stealing food from turtles.
Data from the Hong Kong government shows that the city’s rate of rat infestation is significantly lower today than it was ten years ago. That’s cold comfort to the British tourist whose feet were gnawed by a rat on Pottinger Street in late May, or the woman bitten in a Lam Tin supermarket in June, or the man who suffered a bite two weeks ago while taking an afternoon nap at his home in Kwun Tong. One question is on everyone’s mind: what’s going on?
“It’s the heat,” said Keith Wong, the business manager of Johnson Group, one of Hong Kong’s largest pest-control companies. When the temperature rises outdoors, it becomes too hot for rats to stay underground, where they usually live — so they venture outdoors, sometimes even during the day. Poor hygiene makes the problem worse, he said, by luring rats into areas they might not normally go.
The government offered another explanation: rats that are poisoned bleed to death internally over a period of several days, which can lead to erratic behaviour. “Though they normally are afraid of getting close to humans, intoxicated and weary rodents may behave abnormally by attacking people when they perceive they are being approached or attacked but find it hard to escape,” said a spokeswoman for the Food and Environmental Hygiene Department.
But Wong Tze-wai, a professor of public health at Chinese University, said that such poison has been used for decades, ever since it was discovered that rats learned to avoid food tainted by more fast-acting agents such as arsenic, so it was unlikely to have lead to a sudden spate of rat attacks. Instead, he said, the real reason why there has been an apparent surge in rat activity is because efforts to keep Hong Kong’s streets, markets and restaurants clean have fallen by the wayside.
“The reproductive rate is so fast, there’s no reason for the rodent population to decline just because of trapping, baiting or poisoning,” he said. “As long as rats have something to eat and a place to live, they’ll be fine. You can’t control shelter in a big city, because there are plenty of places to live, like sewers, so the only thing left is to deny them food. But just look at the state of our back alleys and the way we dispose of food in the wet markets.”
The government measures the rat population by leaving bait and seeing how much of it is taken. It then divides the amount of missing bait by the total amount of bait laid to come up with a Rat Infestation Rate (RIR) for a given area. When the rate is above 10 percent, the department will launch an intensive rat-control campaign that includes disinfestation, increased cleaning services and community education.
Last year, the city’s overall RIR was 6.1 percent, down from 16 percent in 2000. Kwun Tong, with a RIR of 12.4 percent, was the only district that exceeded 10 percent.
Wong doubts the effectiveness of using the RIR to determine Hong Kong’s rat population. “If you really want to assess the population, you have to capture a rat in a cage, mark it and release it, and find out how often you catch the same rat again and again,” he said. “But there’s no point in doing that in Hong Kong. We know the population is huge. We know how they thrive. What it really boils down to is environmental hygiene.”
In response to the recent rat attacks, the government has pledged to ramp up its rat-control efforts. But the government’s increasing reliance on contract workers might make that difficult. Last year, the department cut the number of front-line pest-control workers while spending an extra HK$90 million on new management to supervise private contractors. The government’s 670 in-house pest control workers are now supplemented by 1,400 private contractors.
“It’s a mismanagement of resources,” said Li Mei-siu, the vice-president of the Food and Environmental Hygiene Department Staff Rights Union. She said accused contractors of cutting corners on pest control by using cheap equipment and poorly-trained, low-paid workers. The situation is made worse by government supervisors who have little practical knowledge of pest control techniques, she said.
The result is increasingly ineffective rat control. Between 2003 and 2009, according to union figures, the number of rat-infested areas treated by pest-control workers increased from 48,496 to 68,605, yet the number of rats captured and killed declined from 48,297 to 26,601.
The consequences for public health could be very serious. Rats carry the fleas responsible for the plague, a disease responsible for some of the world’s most devastating pandemics. “Fortunately, the disease has not been found in Hong Kong for a long time,” said University of Hong Kong pathologist Samson Wong Sai-yin. But rats also carry a slew of other viruses and harmful bacteria. In the worst cases, said Wong, coming into contact with rat urine or excrement can lead to fever, arthritis, meningitis, hepatitis, pneunonia, infection of the heart valves and kidney failure.
Despite the risks, many people in Hong Kong take a lackadaisical approach to cleanliness. “Even if people are concerned about hygiene in their own private area, they don’t care as much about public areas, and they just rely on the government to clean them up,” said Keith Wong, the pest control specialist.
Quarry Bay resident Virginia Lau has seen the consequences of that attitude first-hand. She was eating with friends in a Sai Wan Ho restaurant late one night when they spotted a big rat repeatedly wandering into the dining area along an exposed pipe. “When we told the restaurant staff to do something about it, they just said not to worry,” she recalled. “The dishwashing lady just said, ‘Oh, happens all the time. I’m used it.’”
This story was originally published in the South China Morning Post on August 1st, 2010.
Tags: Hong Kong, Public Health, Rats, Summer