1. Herpes simplex virus type 1 is a common human pathogen that causes cold sores.
2. Cheng said the equine herpes virus isn't new to Hong Kong but the latest outbreak is the territory's biggest in history.
3. The horses also fell sick despite being vaccinated against the herpes virus, but Cheng said that wasn't a dangerous sign.
4. But researchers think cells in the foreskin of the penis may be susceptible to HPV and the herpes virus.