MONDAY, Feb. 15, 2016 (HealthDay News) -- More cases of the rare but potentially devastating neurological disorder Guillain-Barre syndrome are appearing in some Latin American countries where the Zika virus is also present, according to the World Health Organization.
The United Nations-affiliated health group said in a weekly report Saturday that Guillain-Barre syndrome, which can cause temporary paralysis, has been reported in Brazil, Colombia, El Salvador, Suriname and Venezuela, the Associated Press reported.
But, the WHO added, the "cause of the increase in GBS (Guillain-Barre syndrome) incidence . . . remains unknown, especially as dengue, chikungunya and Zika virus have all been circulating simultaneously in the Americas."
According to the U.S. National Institutes of Health, Guillain-Barre syndrome is a rare disorder that causes the immune system to attack the peripheral nervous system. As a result, muscles have trouble responding to signals from the brain. No one knows what causes the syndrome. Sometimes it is triggered by an infection, surgery, or a vaccination.
Patients typically reach the point of greatest weakness or paralysis days or weeks after the first symptoms. The symptoms then stabilize for a period of days, weeks, or even months. The recovery period may be as little as a few weeks or as long as a few years, according to the NIH.
Meanwhile, U.S. health officials began shipping test kits for the Zika virus late last week to health departments around the country. They are to be used by pregnant women returning from Latin America and the Caribbean, where the virus may be to blame for severe birth defects.
The U.S. Centers for Disease Control and Prevention is also recommending that pregnant women avoid those regions of Central and South America and the Caribbean where Zika virus has been identified and officials have described it as spreading "explosively."
So far, the epidemic has seemingly been limited to Brazil. It is suspected -- but not proven -- that the virus is to blame for a birth defect called microcephaly that causes babies to be born with abnormally small heads and possible brain damage.
The CDC is telling doctors to test the women for Zika infection between two weeks and 12 weeks after they return home. Those thought to have been infected could then have ultrasound scans to monitor their fetus' development.
The CDC's director, Dr. Tom Frieden, said Thursday that the agency has shipped about 12,000 of 62,000 available Zika tests to health departments in three dozen states and is working to produce 30,000 more tests.
The CDC has said it does not expect the Zika virus, which is transmitted by mosquito bites, to become widespread in the United States.
Frieden and Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, appeared before a Congressional panel last week to lobby for President Barack Obama's request for $1.8 billion in emergency funds from Congress to combat the threat of Zika virus.
The Zika virus was first identified in Uganda in 1947, and until last year was not thought to pose serious health risks. In fact, approximately 80 percent of people who become infected never experience symptoms.
But the increase of cases and birth defects in Brazil in the past year -- believed to exceed more than 4,100, making that nation the epicenter of the epidemic -- has prompted health officials there to warn pregnant women or those thinking of becoming pregnant to take precautions or consider delaying pregnancy.
On Thursday, it was reported that two American women who had contracted the Zika virus while traveling abroad had miscarried after returning home. The virus was found in their placentas, according to a CDC spokesman, the Washington Post reported.
This is the first time that U.S. health officials have reported miscarriages in American women who had become infected while traveling abroad, although there have been many miscarriages reported in Brazil, the newspaper said.
Since the Zika epidemic first surfaced in Brazil last spring, the virus has spread to 30 countries and territories in Latin America and the Caribbean. The World Health Organization now estimates there could be up to 4 million cases of Zika in the Americas in the next year.
The Obama administration's request for funding would allow for an expansion of mosquito-control programs, speed development of a vaccine, develop diagnostic tests and improve support for low-income pregnant women.
The earliest a vaccine could be developed would be some time next year, Fauci has said.
For more on Zika virus, visit the U.S. Centers for Disease Control and Prevention.
To see the CDC list of sites where Zika virus is active and may pose a threat to pregnant women, click here.