Rats are vectors as they can transmit diseases to humans and animals. Rat-transmitted diseases, such as leptospirosis, hantavirus and murine typhus, can be passed to humans through direct contact or breathing in dust contaminated with rat urine or droppings, or via a flea bite from an infected rat.

There are three common rodent species in Singapore: Rattus norvegicius (Norway rat), Rattus rattus sp. (Roof rat) and Mus musculus (House mouse).

Though similar in appearance, their features vary slightly (see table below).

The Suncus murinus, or the Asian House Shrew, is a nocturnal animal with similar reproductive prowess. It is an insectivore and often mistaken as a rat, but can generally be differentiated from a rat by its pointed snout, its shorter thicker tail, and smaller eyes.

Although shrews are not known to be vectors that transmit diseases, they have been found to harbour pathogens such as hantaviruses and leptospira bacteria. They should thus be regarded as potential disease carriers, and handled with care, much like other wild animals.