If the Zika virus itself wasn't frightening enough, there's yet another birth defect pregnant women have to worry about if they come down with the virus. Arthrogryposis has been added to the list of health issues now associated with Zika (which includes microcephaly, a birth defect in which a baby's head is significantly smaller than expected).
According to a study published in the British Medical Journal, a small number of babies who have been infected with Zika in the womb have developed arthrogryposis, which involves stiffened joints and weakened muscles.
But why is arthrogryposis related to Zika — and how big a threat is it?
"It is assumed the virus interacts with the nerves and blood vessels of the limbs in order to produce this condition," Dr. Amesh A. Adalja of the University of Pittsburgh Medical Center and School of Medicine tells SheKnows. "Arthrogryposis is a condition of the fetus and newborn — not the pregnant woman. It causes joints to be contracted in the newborn."
This lack of fetal movement in the womb can contribute to a further stiffening of joints and the longer the body remains immobile, the worse the contracture.
It needs to be said that arthrogryposis is very rare — in the United States the frequency is about 1 in 3,000 live births, according to Adalja. Zika may be one cause of the condition, but various other viruses, as well as abnormalities, can lead to the development of arthrogryposis. Babies born with this defect often have joints that are restricted from free movement, and sometimes the joints become stuck in one position. The diagnosis cannot be made via ultrasound, but doctors can detect abnormal limbs and proceed with follow-up blood tests. Preparations can also be made for a baby that is breech and possibly infected with arthrogryposis to ensure he or she is delivered via cesarean.
In Brazil, where Zika was first detected in 2015, seven babies were recently born with arthrogryposis — six of those babies also suffered from microcephaly and two of the babies tested positive for Zika (the other babies have not been tested because the Zika test is apparently not widely available in Brazil). Researchers believe the Zika virus caused neurological issues, which affected the fetuses' ability to move inside of the womb. As of right now, the connection between Zika and arthrogryposis is being called an "association" and it isn't yet clear whether Zika actually causes the birth defect.
There's a good chance we're going to be hearing a lot more about arthrogryposis in the future. The CDC has reported that 15 babies in the U.S. have been born with Zika-related birth defects and seven women have miscarried because of Zika. Sadly, health officials in Texas reported this week that a baby whose mother had traveled to Latin America while pregnant died shortly after birth. Considering that more than 7,300 Americans have been diagnosed with Zika and there continues to be a great deal we don't know about the virus, Zika-related illnesses are going to continue to be a concern until we gain more clarity on the matter.
There are no antiviral treatments for Zika, nor is there a vaccine, though Adalja says phase one clinical trials have just begun with a few candidate vaccines. As for arthrogryposis, Adalja says it is treated with modalities, such as physical therapy and splinting. There is no cure for the birth defect, but it is not a progressive illness and children who have been affected by it can go on to have normal speech and learn independently.
We still have a lot to learn about Zika, and as of right now, there is a lot to fear. It helps to keep conditions like arthrogryposis in perspective: Take every precaution possible against Zika, but understand arthrogryposis is very rare.
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