Pat Gosain is a religious festival of West Bengal
. This festival is dedicated to the neem tree (Azadirachta indica), which is believed to be the abode of Goddess Sitala
. According to mythology, the goddess can inflict a person with small pox and also cure him. This disease is said to be the manifestation of the goddess.
A person afflicted with small pox is given a rub using neem leaves. These leaves are believed to have a cooling effect, which is required by the patient. The leaves also have the effect of driving away the fever demons, which bring about the heat prostration.
Goddess Sitala is therefore worshipped during the Pat Gosain.