[Medical Q&A] Can I be infected with hepatitis B by being bitten by a mosquito?

Planner: Chinese Medical Association

Reviewer: Ye Qing, Chief Physician, Tianjin Third Central Hospital

Many people have this question: If someone in the family has hepatitis B, and a mosquito enters the house, will other people be infected with hepatitis B after being bitten? The answer is no.

When mosquitoes bite people, they pierce the skin through their mouthparts and suck blood. At the same time, they secrete saliva into the human skin tissue, causing an allergic reaction. This is why a big red bump appears after being bitten by a mosquito, and it itches and hurts. In addition, the process of mosquitoes sucking blood is generally one-way. After biting a human body, they basically will not inject their own blood or the blood sucked last time into other people's bodies. Even if a mosquito bites a hepatitis B infected person, the amount of virus inhaled is very small, and the hepatitis B virus is difficult to survive in the mosquito's body, and it will not reproduce in the mosquito's saliva. Even if the mosquito carries a small amount of hepatitis B virus, it is not enough to spread to the next host through a bite. Please remember that the main transmission routes of hepatitis B are blood transmission (such as blood transfusion, shared needles, etc.), sexual contact transmission, and mother-to-child vertical transmission. No research has shown that mosquitoes can transmit hepatitis B virus. Developing good hygiene habits and scientific protection can effectively reduce the risk of hepatitis B transmission.