This is Ray Freeman.
And this is Bob Doughty with Science in the News, a VOA Special English program about recent developments in science. Today, we tell about an operation that separated twin babies joined at the head. And we tell about the spread of West Nile virus in the United States.
Earlier this month, doctors in California separated two baby sisters joined at the top of the head. A large operating team successfully divided the head bones and skin of Maria Teresa (mah-REE-ah teh-RAY-sah) and Maria de Jesus Quiej-Alvarez (mah-REE-ah deh hay-SOOS key-ek-AHL-veh-rez). The doctors also disconnected and re-directed some of the girls’ blood vessels.
This operation on the one-year-old twins took twenty-two hours. A few hours later, doctors operated on one of the babies to stop bleeding on the brain. Doctors performed the operations at the Mattel Children’s Hospital at the University of California at Los Angeles. The two Marias were born in Belen (beh-LEHN), Guatemala, with their heads joined at the top. The babies faced opposite directions.
Experts say this condition is extremely rare. Only about one in two-and-one-half-million live births results in twins being joined at the head. It is one of the rarest examples of conjoined or connected twins. Normal twins who are exactly alike result when a fertilized egg separates into two embryos early in the mother’s pregnancy. Twins become connected when a fertilized egg fails to completely separate.
At least fifty medical experts took part in the operation on the Guatemalan babies. To separate the sisters’ heads, the doctors had to disconnect blood vessels that the babies shared. However, the twins did not share a major vein called the sagittal (SAJ-it-al) sinus. This vein passes over the top of the skull from the front to the back. Then it divides to take blood back to the heart.
Doctors said the fact that each girl had her own sagittal sinus was very good news. It meant the doctors did not have to decide which twin would get the vein, or try to build one vein for each child.
The babies did share some bone structure. Each, however, had a separate brain. In the future, the doctors say they will have to rebuild areas around the girls’ brains and skulls. This operation will make their heads appear more normal.
Doctors were pleased that the girls were moving their hands and feet after the operation. The babies also were looking around and reacting to their nurses. However, it will not be known for some time if either or both suffered brain damage.
A group in Spokane, Washington, called Healing the Children, brought the babies and their parents to Los Angeles for the operation. The girls’ parents decided on the operation to separate the twins after being told their babies might not survive without it.
Most twins connected at the head die. Between forty and fifty cases of twins joined this way have been reported over the years. Only about fifteen percent lived to age five. Only one set grew up to become adults. Organ failure usually causes the deaths. The heart and kidneys of one twin carry most of the responsibility for both bodies. When the organs fail, both twins die.
In the past, about thirty operations were performed to separate twins joined at the head. Most of the babies suffered brain damage. Half of them died.
Two other conjoined twin girls were separated in an operation in Baltimore, Maryland, in April. These babies were joined at the chest. Doctors at the University of Maryland Medical Center operated on Loice (low-EES) and Christine Onziga (kris-TEEN ahn-ZEE-gah). The babies were born in October of last year in Leiko, (LAY-co) a village in northern Uganda.
The twins shared a liver. First, the doctors separated that organ. Then they temporarily tied off a blood vessel that connected the babies’ hearts. The doctors were extremely pleased to see that each heart could beat independently. This permitted them to cut the blood vessel. Each girl was left with a small opening in her heart. Doctors say they can repair this without further surgery.
The doctors also rebuilt part of the walls of the twins’ chests and abdomens. And, they rebuilt part of the muscular tissue that separates the abdomen and chest. Loice and Christine now appear to be developing normally. They are expected to return to Uganda with their parents in October if they continue to do well.
Years ago, connected twins were called “Siamese twins.” This was because the first well known joined twins were born in Siam, now called Thailand. The twins, Chang and Eng, were born to Chinese parents in eighteen-eleven. A narrow piece of skin joined their lower chests. Their livers were connected through that skin. Chang and Eng grew up and married sisters in the eighteen-forties. Over the years, the two became fathers of twenty-one children. Several times during their lives, Chang and Eng considered separation surgery. But they decided against it. They died in eighteen-seventy-four.
A viral disease is infecting people in many parts of the United States. By the end of last week, the West Nile virus had killed at least nine people. It has infected more than one-hundred-sixty people in at least twelve states and the District of Columbia. The virus has been discovered in at least thirty-eight states in horses, birds or mosquito insects.
Health officials say West Nile virus is spread by mosquitoes that feed on the blood of infected birds and then bite people. Recently, the director of the Centers for Disease Control said Americans will have to deal with the virus for a long time. Julie Gerberding said the virus is well established among populations of birds and mosquitoes in this country.
However, the time of year of the current outbreak has concerned health officials. Doctor Gerberding noted that people developed West Nile virus in August and September in the past. Yet, this current outbreak began in June. It appears to be getting worse at the time when the disease usually begins.
West Nile virus was first observed in the West Nile area of Uganda in nineteen-thirty-seven. Forms of the virus have appeared in recent years in widely separated countries. In the nineteen-nineties, the disease was reported in Algeria, Romania, the Czech Republic, the Democratic Republic of Congo, Russia, the United States, France and Israel.
West Nile virus was first reported in the United States in nineteen-ninety-nine. That outbreak in New York City killed seven people. It also caused more than sixty people to seek treatment in hospitals. The virus has been spreading to other states since then.
West Nile virus is one of a group of viruses that can cause high body temperature and pain. The viruses can also affect the senses and balance of a person. It is among a group of organisms called flavi-viruses (FLAY.vi.vie.rus.es). The disease Japanese encephalitis is similar to West Nile virus.
Only about one in five people who are infected with the virus become sick. Signs of the disease include muscle aches, pain in areas where bones are joined, high body temperature, headache and tiredness.
West Nile virus can cause serious disease or death among older people and people whose defense system against disease is weakened. It can cause encephalitis, an inflammation of the brain. It can also cause meningitis, inflammation of tissues around the brain or spinal cord. However, fewer than one percent of people infected with the virus become seriously sick.
John Barry is a biology researcher. He wrote in the New York Times newspaper that the current outbreak is not really unusual. He noted that a virus closely related to West Nile virus, called Saint Louis encephalitis, infected about two-thousand people in nineteen-seventy-five. It then almost disappeared.
Lyle Petersen of the Centers for Disease Control also noted that the hot summer weather may have caused an increase in the viral infections. Warm temperatures make it possible for mosquitoes to reproduce more effectively.
Cases of West Nile virus are expected to decrease as autumn comes and temperatures drop. Several experts say it may take years before they understand the development of the disease in this country.
This SCIENCE IN THE NEWS program was written by Jerilyn Watson and Mario Ritter. It was produced by George Grow. This is Bob Doughty.
And this is Ray Freeman. Join us again next week for more news about science in Special English on the Voice of America.