Mobile text messages, also known as SMS, are helping to prevent the spread of Ebola in West Africa.
Close to 5000 people have died from the virus since last March, and more than 10,000 have been infected.
The most recent SMS campaign took place in Senegal when the government sent 4 million mobile messages to warn of the dangers of Ebola after one reported case, which was quickly isolated.
The platform they used is called mHealth, created by the World Health Organization (WHO), which initially intended to help people manage diabetes.
Stephanie Coutrix spoke with Dr Edward Kelley from WHO in Geneva, who explained the efficiency of SMS campaigns.