The rat problem has long flourished on crowded streets, parks and alleys of Hong Kong (China), despite years of efforts to eradicate and complaints about rat rampant.
I used to live in an area with a lot of rats, and when I moved to a new place, there were still a lot of rats. They are very big," a Hong Kong (China) resident named Rain said.
Now, this populous city is shifting to using artificial intelligence, using thermal imaging cameras to monitor the activity of rodents, mainly at night.
The AI application monitoring system, introduced in 2024, analyzes these thermal images to create the "Rack Ratio" (RAR) - the percentage of images taken at a place without a mouse - to help authorities cordon off hamlets more effectively.
According to the Hong Kong Food and Environmental Sanitation Bureau (China), data collected in 2025 shows a "significant improvement" in areas with more rats. However, government data also shows that dozens of survey locations recorded RAR below 80%, meaning that for every five images taken in these places, more than one still shows rats.
With a city of more than 7 million people, experts believe that the rat problem in Hong Kong (China) is still an environmental management challenge that AI can support monitoring, but cannot solve on its own.
It is a measure that must be supplemented with many other measures. We measure food sources, food availability, and whether it increases or decreases?" - said Bobby Corrigan, an expert on urban rodents in New York, who has designed rat control programs for cities in the US and Canada for about 20 years.
The rat problem also attracts attention due to its impact on public health. In May, Hong Kong (China) recorded the first human rat hepatitis E infection in the year. About 1/5 of rats carry this virus. Although rarely transmitted to humans, humans can still be infected with the virus through food or water contaminated by rat waste.
Symptoms may include fever, nausea and vomiting, although some infected people do not have symptoms. Severe cases can lead to liver failure. Dr. Siddharth Sridhar - Associate Professor of Clinical Laboratory at the Department of Microbiology, Hong Kong University (China) - said that the number of cases globally is increasing, with more than 50 cases recorded so far. And in Hong Kong (China), this has become the most common mouse-to-human virus.
Despite advances in surveillance technology, experts believe that completely eliminating rats is unrealistic. Rats reproduce in the vast sewer system of Hong Kong (China), making it impossible to accurately determine the total number. Experts argue that sustainable improvements will depend on human behavior no less than technology.
