A parent's worst nightmare came to life this month, with two couples seeing their infants hospitalized for neonatal herpes, leaving one dead and another in recovery.

While neonatal herpes is extremely rare, the consequences for a newborn baby with an undeveloped immune system can be devastating, as the parents of Mariana Sifrit can confirm. Both they and Samantha Rodgers, the mother of another baby who contracted the infection, are speaking out to alert parents as to what can happen to a baby who is kissed—or even just touched—by a carrier of the virus.

On July 5, just six days after Marina was born, her parents rushed her to a local hospital, concerned that she wasn't waking up. Testing revealed that the newborn had viral meningitis, caused by herpes simplex virus-1 (HSV-1.) Doctors believed that the baby contracted HSV-1 after receiving a kiss from an infected person; both her parents tested negative. Mariana's condition steadily worsened, and within days, her organs had begun to shut down. She died on July 18.

The second case, of Juliano Rodgers, had a happier ending, as he recovered from a case of HSV-1 after developing cold sores all over his body. His method of transmission was likely the same, a kiss or touch from someone with the virus.

It's hard to know how many cases of neonatal HSV-1 there are every year. One study, published in the New England Journal of Medicine, put the number somewhere between 1 in 1,700 live births and 1 in 8,200. A three-year study in Canada found it to be even more rare, at 1 per 16,000 live births.

In an interview about Mariana Sifrit's death, Rebecca Pellet Madan, clinical associate professor of pediatric infectious disease at NYU Langone Health, told the website Insider that there about 1,500 cases in the U.S. every year.

It's also hard to estimate how many babies die from the infection. Madan estimates about 60 are killed every year, while a study of neonatal herpes in New York City found 34 deaths from 1981 to 2013. For comparison, the leading cause of infant death in the United States is congenital birth defects, with 4,700 deaths in 2014, according to government statistics. 

What complicates the research even more is that in many cases, the herpes virus was transmitted during birth from a mother who was already carrying the virus. While infants born with HSV-1 are often born premature and experiencing complications like low birth weight, those who pick up the virus after birth show no signs of infection until symptoms begin to appear. 

The American Academy of Family Physicians cautions that the virus can be difficult and time-consuming to diagnose. "By the time diagnosis is made," the group warns, "many infants have severe disease and have developed complications. When diagnosis is delayed, mortality is high despite antiviral therapy."

Therapy, when administered quickly, can save a baby's life. But if untreated, complications can quickly arise, becoming as severe as the meningitis that claimed Mariana's life. 

To minimize the risk of newborns contracting either HSV or any other easily transmitted disease, such as the flu or respiratory infections, Madan offered some simple tips, echoed by pediatric nurses with whom ATTN: spoke.

"Everyone should wash their hands before touching a young infant," Madan said. "Parents should avoid kissing babies directly on their eyes or mouth. People who have a runny nose, cough, or cold symptoms should avoid visiting a new baby. Get outside for fresh air with your newborn, but try to avoid crowded places. And babies who are old enough to receive their first immunizations should receive them on time."