In the space of just two months, a spate of rat-related incidents and infestations have hogged the headlines.
In December, Singaporeans were horrified by an online video that did the rounds, showing a hilly area next to Bukit Batok MRT station crawling with rodents.
Next, at the opposite end of the island, Punggol residents also reported numerous rat sightings, prompting the Pasir Ris-Punggol Town Council to take action.
Then, last week, the National Environment Agency (NEA) announced that it had found rodent activity in the false ceilings of 14 food and beverage establishments in the Marina Square shopping centre.
It conducted inspections after a customer found a rat in a tray of vegetables at Hotpot Culture, a restaurant in the mall. A photograph of the stew complete with the furry dead rat also did the Internet rounds.
After the Bukit Batok infestation was highlighted in the media, readers wrote to The Straits Times to complain about rats in neighbourhoods such as Ang Mo Kio, Yishun, Marine Parade and Jurong.
Is the rat problem getting out of hand? What more can be done to curb it?
Statistics from the NEA show that, indeed, the rodent problem has been getting worse in the last two years.
In 2011, it started an islandwide programme to monitor the rodent population and identify priority areas for treatment.
Its inspections of public areas in October and November last year uncovered about 10,000 rat burrows across the island - up from 6,400 in the same period in 2013.
The Government has also said that more than 35,000 burrows were found and their inhabitants killed in the first 11 months of last year.
Before the 2011 programme kicked off, in 2009 and 2010 a series of rat infestations were reported in Orchard Road, the Geylang Serai wet market and Lau Pa Sat hawker centre. In 2010, the NEA also found 1,700 areas with rats, a four-fold surge from the 443 infested areas discovered in 2009.
However, without comparing like for like in terms of burrows, it is unclear whether the rat situation now is worse than in 2010 or previous years.
But what is clear - although it is no consolation - is that rat infestations are not new in Singapore, and outcries over them seem to resurface every few years.
Reasons behind the recent spike
ONE reason the rat problem is getting worse could be that more people are not properly disposing of food waste.
Rats can multiply exponentially if they have enough food.
The Norway rat, one of the more common rat species here, gives birth to three to six litters each year, with about seven to eight babies per litter. The rats reach sexual maturity 10 to 12 weeks after birth.
The NEA said an adult female Norway rat and her offspring can add up to 2,500 rats to the population in a year, assuming every rat in each litter survives.
Pest controllers said the growth in Singapore's human population has led to more food waste that is not disposed of properly, causing the rat population to grow faster.
In 2013, 696,000 tonnes of food were thrown away and not recycled, about 30 per cent more than the 529,400 tonnes in 2009.
The pest control firms said buildings such as malls and hawker centres typically aggregate tenants' trash - including large volumes of food waste - in large bins at bin centres.
The lids of these bins may not be closed properly. They also usually have a hole plugged by a cork that allows liquids but not solids to flow out, partly so cleaners can wash the insides of the bins easily.
But some cleaners remove the corks permanently to make their job even easier, leaving a hole in the bin which rats can use to get to the food waste.
To save money, some building managers also do not replace bins that have holes gnawed in them by rats.
Pest control firms added that construction activity across the island may have flushed the rats from their nests.
And as more buildings are connected to one another, such as malls with linkways, rats, too, find it easier to spread even farther.
Why is the spread of rats such a problem?
Pest controllers pointed out that rats carry diseases. If the rats come into contact with food, they could pass on diseases like salmonellosis, which can cause diarrhoea, fever, vomiting and dehydration.
In 2012, a foreign worker's death was linked to leptospirosis, a bacterial infection spread from rats to humans.
Fleas on rats can also spread murine typhus, which causes high fever, severe headaches and body aches. However, there are fewer than 100 confirmed cases of murine typhus each year.
The spread of disease is not the only concern: Star Pest Control's general manager Bernard Chan said that rats gnaw on power cables to sharpen their teeth.
"If the wires are exposed, people may be electrocuted by live wires during maintenance work, the electricity supply may become unstable and household appliances could catch fire," Mr Chan said, although he has not seen such incidents.
Not just a job for the authorities
THE NEA's programme that began in 2011 involves working with town councils to undertake measures such as trapping rats and sealing burrows.
Twelve public areas, including those in Geylang, Joo Chiat and Orchard Road, have received special attention because of their high density of eateries and human traffic.
The NEA said the rodent situation in these areas is largely under control, with the number of burrows found falling from 119 in March last year to 11 in December.
The agency also carried out more than 144,000 inspections of food shops last year, and has audited 85 out of more than 200 shopping malls so far to make sure their anti-rodent measures are adequate.
This includes physically inspecting the malls and advising their managements to, say, plug holes and gaps in walls to prevent rats from entering and breeding on their premises.
But the NEA noted that other people, such as landowners and building managers, must also play their part to prevent infestations, for example by keeping their premises clean, storing food and food waste in rodent-proof containers, and conducting routine pest control checks and treatment.
However, this may not be happening in some places. Several pest control firms said that some building owners, to save money, do only the bare minimum to resolve their rat issues.
Mr Carl Baptista, technical director of Origin Exterminators, added that building owners are usually not trained pest controllers, so even conscientious ones have to trust the firms they hire to do a proper job.
Some pest control firms, possibly through a lack of knowledge, may not be attacking the root causes of the infestations, he said.
Building managers may think progress is being made if the firm catches rats. But if the rats' sex is not identified, the firm could be catching just male rats that forage for food, and not pregnant female ones.
"If the pregnant females are not caught, the problem will come back. It could even get worse, since the rats can learn how to avoid the traps," he said.
To make matters worse, Star Pest Control's Mr Chan said the rats may be changing their behaviour to adapt to Singapore's increasingly urban environment.
The Norway rat traditionally burrows into the ground to make its home, or lives in sewers. But pest controllers have noticed increasing numbers of them living in gaps in or between building slabs and other structural defects.
As Singapore continues to become more built-up, any negligence or ignorance on the building managers' part may lead to more rat infestations.
Time to clean up attitudes towards litter
SINGAPOREANS also need to be more responsible in keeping the country clean. Last year, the NEA handed out 19,000 summonses for littering, double the number in 2013.
Instances of rubbish bins overflowing with trash, including food waste, have become depressingly common, especially in places where people gather to relax, such as East Coast Park.
All of this contributes to an environment that encourages rats to multiply.
Food left by kind-hearted people for stray dogs and cats may also be inadvertently fuelling the apparent rat population explosion.
Some of this can be easily solved.
The stray feeders should feed stray dogs at a fixed time at the same spot every day. To be even more responsible, the feeders should stay to make sure the food is not eaten by rats, and then remove leftovers.
A more drastic solution may be to require rubbish collectors to pick up trash at night, when rats typically forage, instead of in the morning.
But a simpler and more effective solution is to get Singaporeans to clean up after themselves and generate less trash - particularly food waste - to begin with.
Singapore's rats will always present a gnawing problem.
But the rodents can be kept under control if humans do their bit, with measures such as sealing burrows, effective pest eradication and, of course, removing a key element to the scavengers' proliferation - food waste - and easy access to it.