When actress and producer Salma Hayek arrived in Sierra Leone in September, she was not whisked off to a movie set.
She was there not as a celebrity, but as a humanitarian, to see firsthand a leading cause of death in the developing world: tetanus.
"Nightline" co-anchor Cynthia McFadden went along to document the journey.
To most people in the United States, tetanus brings to mind rusty nails and a quick trip to the doctor's office for a shot. But in developing countries like Sierra Leone, maternal and neonatal tetanus (MNT) is a top cause of death among mothers and their babies.
Hayek said that she didn't know what to expect from the trip.
"I was just open to this experience and it's been quite an amazing one," she said.
Sierra Leone has the highest infant and child death rate in the world. One in five children die before reaching their fifth birthday and tetanus is a big contributor -- 21 percent of all infant deaths are related to tetanus.
Tetanus deaths are preventable with routine vaccinations. UNICEF has launched an initiative to eradicate the disease worldwide by 2012. In Sierra Leone the cost of immunizing one person is about 74 cents.
Once a woman is immunized, her children will be protected from the disease at birth, before needing immunizations of their own.
In 2008, Hayek became a spokeswoman for the Pampers "One Pack = One Vaccine" campaign to support UNICEF's efforts to eliminate tetanus. For each pack of specially marked Pampers diapers sold, parent company Proctor and Gamble donates the cost of one tetanus vaccine to UNICEF. The North American campaign has generated funding for more than 45 million vaccines since the beginning of 2008.
"What really excited me about this was the concept of mothers from around the world working together to protect children," said Hayek, who is the mother of a 16-month-old daughter named Valentina.
"The thought of somebody in Los Angeles, where I come from, purchasing the one pack of Pampers ... by doing this that they were going to do anyway, they could ... provide one vaccine for another mother somewhere else in the world, someone they don't know ... these anonymous women around the world coming together to protect women and to protect children was really exciting."
As soon as she landed in Sierra Leone, Hayek was taken to a hospital in the country's capital of Freetown where she saw the painful reality of tetanus. A 7-day-old baby girl named Fatima lay dying. There were no medications to give her but the serum given to horses with the disease.
"I was talking to this little girl and I was touching her and there was the slightest reaction, like she took a couple of breaths," Hayek said. "And then I felt guilty to be in that room because I felt we were taking away oxygen. And as I walked out, I knew it. I felt it, the baby passed away. "
"Her mother was so young and to lose a baby within one week at the age of 19, I cannot think of a worse thing to happen to someone than to lose a baby," she said.
In countries like Sierra Leone, still recovering from an 11-year civil war that ended in 2002, high death rates are due to a combination of deficient health services and education.
Most women have not been vaccinated because of insufficient resources or a lack of information about the preventive measure.