* Experts say getting all women to antenatal care is key
* Screening could halve syphilis-related perinatal deaths
By Kate Kelland
LONDON, June 16 (Reuters) - Cheap, simple tests and treatments for syphilis in pregnancy could prevent more than half of newborn deaths and stillbirths related to the disease, which kills 500,000 a year in Africa, a new study has found.
Research by British scientists published in The Lancet Infectious Diseases journal on Thursday found that syphilis is a major cause of infant death in many poorer countries and that antenatal syphilis screening is one of the most cost-effective ways of improving newborn and child survival.
Some 2 million pregnant women are infected with syphilis globally each year and around 1.2 million of these transmit the infection to their baby, who may be stillborn, born early, born with a low birth weight, or congenitally infected as a result.
Experts say an estimated one million babies die each year from congenital syphilis.
Yet for as little as $1 or $1.50, all pregnant women could be screened for syphilis using a standard blood test and treated with the cheap antibiotic penicillin if they were found to have the disease, said Sarah Hawkes from University College London.
"It's incredibly cheap, you can do it with a simple blood test -- and women often have blood tests during antenatal care anyway," Hawkes said in a telephone interview.
"But we need to get all women who are pregnant to come to antenatal care early enough to be able to make a difference."
Syphilis is a curable infection caused by a bacterium called Treponema pallidum. It is sexually transmitted, and can also be passed on from a mother to her foetus during pregnancy.
The World Health Organization estimatesthat 12 million new cases of syphilis occur every year. In developing countries, between 3 and 15 percent of women of child-bearing age have it.
Most people with syphilis tend to be unaware of it and so can unwittingly pass it on during sex or to an unborn child. The worst outcomes of syphilis in pregnancy can be prevented if the infection is detected and treated before around 28 weeks.
In a study known as a meta-analysis, Hawkes' team reviewed the evidence for ways of increasing syphilis testing and treatment rates and improving pregnancy outcomes.
Their review included 10 studies and more than 41,000 women and showed offering women same-day testing and treatment could cut perinatal deaths -- which includes stillbirths and miscarriages -- by 54 percent. Looking at stillbirths alone, the deaths could be reduced by 58 percent, they found.
"What this review shows is that screening is extremely effective at bringing down death rates and illness rates, but unfortunately the majority of pregnant women in the world are still not screened for syphilis," Hawkes said.
In a comment on the study's findings, Peter Piot, director of London School of Hygiene and Tropical Medicine, said it was a reminder that syphilis is not a disease of the past, but a major cause of death for hundreds of thousands of newborn babies.
"We can so easily stop this," Piot said. "Syphilis is invisible: if you don't test for it you don't find it."