BALTIMORE — Researchers at Johns Hopkins Medicine working with scientists in Colombia have discovered what they believe is the strongest evidence yet that the Zika virus causes neurological problems in adults.

Much of the research on the mosquito-borne Zika has focused on pregnant women, because the virus can cause microcephaly in fetuses, causing babies to be born with brain damage and abnormally small heads.

The new research shows that the health effects might be more widespread.

Hopkins researcher Dr. Carlos Pardo said the research, published in the New England Journal of Medicine, bolsters concerns that Zika can lead to the neurological disorder Guillain-Barre in adults. Until now, the virus was thought to be linked to the disorder only in rare cases.

Guillain-Barre is a nervous system disorder in which a person's immune system attacks the nerves, in the worst cases eventually paralyzing the body.

The exact cause of the disorder is not known, but research has found its symptoms often erupt after a viral or bacteria infection. It affects one or two out of 100,000 people who first suffer from infections.

Most people recover from the disorder, but some side effects — such as weakness or numbness — may persist. Research has shown that Guillain-Barre can lead to vision problems in some people.

The Hopkins findings come a week after Congress allocated $1.1 billion for research and aid to fight the spread of Zika as scientists across the world discover more about its effects on people's health.

Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention, has said health officials are becoming more concerned about the disease.

Researchers are beginning to believe that even babies born without microcephaly may suffer problems after birth.

The CDC reports that there have been 3,625 cases of Zika in the mainland United States, and another 22,000 in U.S. territories such as hard-hit Puerto Rico. There have been 808 confirmed cases in pregnant women in the continental United States. Twenty-one babies have been born with birth defects and five pregnancies have been lost.