Zika outbreak: FDA advises screening for all blood centres

The U.S.Food and Drug Administration wants all U.S. blood banks to start screening for Zika virus, a major expansion intended to protect the U.S. blood supply from the mosquito-borne disease.

The new advisory means all U.S. states and territories will need to begin testing blood donations for Zika. Previously, the requirement was limited to areas with active Zika transmission, such as Puerto Rico and two Florida counties.

• Blood donations to be deferred for Zika travellers: Canadian Blood Services

Blood banks already test donations for HIV, hepatitis, West Nile virus and other blood-borne viruses.

No change to Canadian blood screening

Last month, the FDA told blood centres in Miami and Fort Lauderdale to immediately stop collecting donations until they could begin screening each unit of blood for Zika. The order followed now-confirmed reports of local Zika transmissionthe first in the continental U.S.

Canadian Blood Services said no changes are planned to current restrictions.

"We've determined the risk of Zika virus entering the Canadian blood system to be extremely low," a spokesman said in an email. "As we monitor the situation, we are prepared to update our screening criteria should it pose a risk to the Canadian blood supply."

Zikais mainly spread by mosquitoes, and causes only a mildillness in most people. But infection during pregnancy can lead tosevere brain-related birth defects.

As of Thursday,232 travel-related cases, twosexually transmitted cases and threereports of maternal-to-fetal transmission have been detected, according to the Public Health Agency of Canada.

The risk for people in Canada is consideredlow.

Travellersare advised toprotect themselves from mosquito bitesat all times.

Zikalikely spread sexually fromasymptomaticman: study

Meanwhile,U.S. health officials are reporting the first case ofZika spread through sex by a man with no symptoms of the disease.

In earlier cases of sexual transmission, the virus was spread bysomeone who at some point had symptoms.

Friday's report details the case of a Maryland man who went tothe Dominican Republic, where there is a Zika outbreak. He didn'tget sick but his female sex partner did and recovered.

Doctors believe Zika spread from someone with no symptoms isextremely rare. They said the case is not reason enough to changehealth advice to couples.

The study, published in the U.S. Centers for Disease Control and Prevention's weekly report on death and disease, suggests that sexual transmission of Zika is no less likely in asymptomatic individuals than in others with symptoms.

Current recommendations for preventing sexual transmission of Zika in returning travellers now differ depending on whether the returning traveller is symptomatic and on whether the couple is planning to become pregnant, but that may need to be changed.

Guillain-Barr tracked in Puerto Rico

Separately, health officials in Puerto Rico have reported as many as 10 people who developed the paralyzing neurological disorder known as Guillain-Barrsyndrome as a result of Zika infections.

The latest studies add to the evolving picture of the impacts of Zika, a virus previously considered to be mild but which has recently been shown to cause the serious birth defect known as microcephaly, as well as neurological illness in adults.

In Puerto Rico, where Zika arrived in December 2015, health officials have been systematically tracking cases of Guillain-Barrsyndrome following reports in other countries showing an increase in cases related to Zika.

Guillain-Barrcauses gradual weakness in the legs, arms and upper body, and in some cases, temporary paralysis.

Overall, the Guillain-Barrsurveillance system identified 56 cases of the syndrome in people infected from Jan. 1 to July 31, 2016, officials from the Puerto Rican health department and the U.S. Centers for Disease Control and Prevention reported on Friday in the CDC's weekly report on death and disease.

Guillain-Barris an autoimmune disorder in which the body attacks itself in the aftermath of an infection, typically occurring in the days following an illness.

Of the cases in Puerto Rico, 34 patients had evidence of a flavivirus infection, such as Zika, dengue or Chikungunya, and 10 had confirmed Zika virus infections. Diagnostic tests cannot easily discern Zika from related infections, but health officials suspect nearly all of the flavivirus infections seen were related to Zika because that is the predominant flavivirus currently circulating in Puerto Rico.

All 34 patients required intensive care, and 12 required a breathing tube and mechanical ventilation. One patient died of septic shock after treatment for Guillain-Barr.

In the sexual transmission case, current guidelines for preventing sexual transmission of Zika suggest that couples in which one person returns from an area with active transmission but did not develop symptoms of Zika should wait eight weeks before attempting to conceive a child.

But men diagnosed with Zika should wait at least six months before attempting to have a child, and women with a Zika diagnosis should wait at least eight weeks.

Health officials said more study is needed to determine the risk of sexual transmission of Zika from asymptomatic individuals.