The list of neurological disorders potentially associated with the Zika virus continues to grow, health officials reported.
Swelling of the brain
In the online edition of the New England Journal of Medicine, French researchers described the case of an unidentified 81-year-old man who had been in fine health before becoming feverish and then comatose while on a cruise in the South Pacific.
An MRI scan and a spinal fluid test indicated that he was suffering from meningoencephalitis, an infection and swelling of the brain.
The elderly cruise ship patient was admitted to an intensive care unit, where doctors were able to make a tentative diagnosis of Zika infection. Within several days, his condition began to improve without treatment, 17 days later his admission to the hospital he was removed from intensive care.
By day 38, he was fully recovered, the investigators said in their report.
Previous research has suggested that the mosquito-transmitted Zika virus also appears to be linked to microcephaly, a birth defect that causes babies to be born with unusually small heads and underdeveloped brains. The virus has also been linked to Guillain-Barre syndrome, an immune system disorder that can occasionally lead to a fatal form of paralysis.
The virus is suspected of causing the epidemic that began last spring in Brazil, where there have been more than 5,600 suspected or confirmed cases of microcephaly with the virus spreading in Latin America and the Caribbean.
Severe potential risks
The man's story and his recovery would seem to reinforce doctors' belief that Zika virus and pregnancy is very dangerous to the foetus. Only one out of every five people infected with Zika show any symptoms, and even those who fall ill usually do not suffer severe symptoms, U.S. health officials have said.
Nonetheless, the World Health Organisation said in the NEJM that, despite the lack of proof linking Zika virus with neurological disorders, "the severe potential risks demand decisive, immediate action to protect public health."
Watch: Another neurological disorder tied to Zika
The WHO recommends such preventive measures as intensive mosquito control; personal protection against mosquito bites; appropriate medical care for all patients with Guillain-Barre syndrome; and proper care for women before, during and after pregnancy.
The United Nations-affiliated agency is also calling for prevention of Zika virus infection through blood transfusion or sexual contract, which seems more likely than had been previously thought.
The U.S. Centres for Disease Control and Prevention has warned pregnant women to refrain from unprotected sex with a partner who has travelled to a Zika-affected region.
For pregnant women, the CDC has this advice:
- Consider postponing travel to any area where Zika virus transmission is ongoing.
- If you must travel to or live in one of these areas, talk to your health-care provider first and strictly follow steps to prevent mosquito bites.
- If you have a male partner who lives in or has traveled to an area where Zika transmission is ongoing, either use condoms the right way, every time or do not have sex during your pregnancy.
The Zika virus has now spread to over 32 countries and territories in Latin America and the Caribbean. The WHO estimates there could be up to 4 million cases of Zika in the Americas in the next year.
New copies of the virus
Last week, researchers reported that the Zika virus may cause the birth defect microcephaly by targeting certain brain stem cells and stunting their growth.
Laboratory studies indicated that Zika can infect a type of neural stem cell that gives rise to the cerebral cortex of the brain, researchers reported in the journal Cell Stem Cell.
Worse, Zika appears to hijack these cells, using them to churn out new copies of the virus and spread more rapidly, the researchers reported.
According to the researchers, the Zika virus flourished in lab dishes containing these stem cells, causing either cell death or disruption of cell growth.
"Although our study hasn't provided a direct link between Zika virus and microcephaly, we identify the direct cell targets of the virus and we show the virus can affect cell growth," said study co-author Zhexing Wen, a postdoctoral fellow at the Johns Hopkins University School of Medicine in Baltimore.
The new findings "provide a potential mechanism how a Zika virus infection can lead to poor brain growth and, therefore, microcephaly," said Dr Sallie Permar, director of Duke University's Laboratory of Neonatal Viral Pathogen Immunity, in Durham, North Carolina.