Scientists warned Wednesday of another possible consequence of a Zika virus infection: inflammation of the brain and the tissue that surrounds the brain and spinal cord.
The indication came from just one case study of an 81-year-old man, but it adds to evidence that the mosquito-borne virus spreading in Latin America and the Caribbean can target and infect the central nervous system.
Researchers already suspected that a Zika infection likely increases the risk of Guillain-Barré syndrome, an autoimmune reaction that affects the nerves and can cause muscle weakness and temporary paralysis. But last week scientists reported that a 15-year-old girl in the French territory of Guadeloupe was suffering from a condition called acute myelitis — or inflammation of the spinal cord — possibly as a result of a Zika infection.
For the case of the 81-year-old, a French team of doctors and scientists wrote in the New England Journal of Medicine that the man had been on a cruise in the South Pacific and New Zealand, during which he was in fine health. Ten days after he returned home to France, he entered the intensive care unit with a fever and in a coma. He developed a rash within the next 48 hours. (One of the places he traveled, New Caledonia, was added Wednesday to the list of destinations the US Centers for Disease Control and Prevention is monitoring for Zika transmission.)
Brain imaging showed signs of meningoencephalitis, an inflammation of the brain and brain covering that is caused by a number of pathogens, including West Nile virus, a close relative of Zika. The doctors could not show definitely that the Zika virus caused the condition, but the man tested negative for infections other than Zika.
The man recovered almost fully within about five weeks, with some lingering weakness in his left arm, the authors reported.
Zika is not a problem for most people who contract it; it generates symptoms in a minority of infections, triggering just a few days of fever, rash, and head and body aches. However, global health officials strongly believe that pregnant women who contract the virus are at an elevated risk of having babies with birth defects.
They initially reported a surge in Brazilian cases of microcephaly, a condition in which babies are born with underdeveloped brains and abnormally small heads. Scientists have since documented cases of other neurological defects in fetuses and babies — including problems with the eyes, fluid in the brain, and the absence of parts of the brain.
Scientists are still investigating whether Zika definitively causes these defects in babies and neurological conditions in adults, but scientists and health officials say the evidence is strong enough that steps should be taken to protect public health now.
In a commentary also published Wednesday in the New England Journal of Medicine, officials from the World Health Organization and the Pan American Health Organization called on researchers to collaborate as they work to understand and combat Zika.
“As the putative link between Zika virus and neurological disorders is reinforced, refined, or even refuted, public health measures will be adjusted accordingly,” they wrote.