18-day-old baby girl dies after contracting meningitis linked to HSV-1, parents say

— -- As they mourn the loss of their newborn daughter, a couple in Iowa are warning parents about whom they allow around their babies in those early days after birth, when infants' immune systems are incredibly fragile.

"Just keep your babies isolated," Nicole Sifrit of West Des Moines, Iowa, told ABC affiliate WQAD-TV recently. "Just don't let anyone come and visit them. Make sure [visitors] constantly are washing their hands. Don't let people kiss your baby. Make sure they ask before they pick up your baby."

On July 1, Nicole Sifrit gave birth to a healthy baby girl, whom she named Mariana Reese Sifrit. Six days later, Nicole Sifrit married Mariana's father, Shane Sifrit.

Hours after the wedding, however, the newlyweds said the baby had stopped eating and appeared lethargic so they rushed her to a hospital. On Tuesday, Mariana died. She was 18 days old.

Baby Dies of Herpes in Ritual Circumcision By Orthodox Jews

Cold Sore Virus Leads to Baby's Death

The Sifrits told WQAD-TV that doctors had diagnosed Mariana with meningitis linked to HSV-1, a form of herpes that can cause cold sores. The Sifrits said herpes led to meningitis, which caused Mariana's death.

Recent research suggests newborns can catch the virus in a variety of ways but most commonly it is acquired via transmission from mother to baby during childbirth.

Of neonatal HSV infections, the article said, 5 percent are acquired in utero, 85 percent are acquired during childbirth and 10 percent are acquired after birth from contact with someone with an active infection.

Both parents were reportedly tested for the virus but their results came back negative. According to the Sifrits, doctors told them Mariana had likely contracted the virus from a kiss by someone with the virus.

"I always thought, like, this is stuff that just happens and it' a shame and never really, never thought it would happen to me ... [I] was not prepared at all," Shane Sifrit told WQAD-TV.

The Sifrits documented Mariana's hospital stay on Facebook, posting that she'd had six blood transfusions. Mariana was later sent from Blank Children's Hospital to the University of Iowa Stead Family Children's Hospital, where she died.

Dr. Alok Patel, a pediatrician with Morgan Stanley Children's Hospital in New York, said the effects of herpes virus in a newborn could be "devastating" and "life-threatening." He said, however, that it was "pretty rare" for a baby to get herpes in his or her bloodstream from a kiss or from transmission that was not by either parent.

"It's very rare to get it from somebody that's kissing your baby or somebody with a cold sore," Patel said, "but it does happen."

In a Facebook post Tuesday, Nicole Sifrit thanked supporters for their prayers.

"Our princess Mariana Reese Sifrit gained her angel wings at 8:41 am this morning in her daddy's arms and her mommy right beside her," Nicole Sifrit wrote. She is now no longer suffering and is with the Lord. Thank you to everyone who has followed her journey and supported us through this. In her 18 days of life she made a huge impact on the world and we hope with Mariana's story we save numerous newborns life. R.I.P. sweet angel."

ABC News' attempts to reach the Sifrits were unsuccessful.