The World Health Organization on Tuesday warned couples who are traveling or have visited areas with the Zika virus that their exposure risk could impact a possible pregnancy.
"Couples or women planning a pregnancy who have been in a Zika virus area should wait at least eight weeks before trying to conceive," WHO said in a statement as many set off on foreign vacations including summer's usual spate of honeymoons.
Zika is a disease spread by Aedes mosquitoes, which typically swarm and bite during the late afternoon hours. These insects are also responsible for spreading such diseases as yellow fever, dengue fever and chikungunya. Zika was first identified in humans in Uganda and Tanzania in 1952, and since January 2007, 64 countries and territories have reported transmission of the virus, WHO said, with outbreaks found in Asia, Africa, the Americas and the Pacific.
Symptoms of Zika infection, according to WHO researchers, are a skin rash and slight fever along with conjunctivitis, muscle and joint pain, malaise or headaches. Typically, those who are infected experience symptoms lasting from two to seven days. There is no vaccine or treatment.
In recent months, however, WHO scientists have noted emerging auto-immune and possible neurological complications from the virus. In February, the organization issued a new statement calling Zika a Public Health Emergency of International Concern. The warning came after a rise in cases of Guillain-Barre' Syndrome and microcephaly in Brazil. The latter causes newborns to have smaller heads, and brains that are underdeveloped.
Zika's continuing spread in South America has heightened international concern because of the Summer Olympic Games, set for Rio de Janeiro from Aug. 5 to Aug. 21. However, WHO noted in a statement May 28 that it saw no need to cancel the 2016 Games amid virus worries.
"Based on the current assessment of Zika virus circulating in almost 60 countries globally and 39 countries in the Americas, there is no public health justification for postponing or canceling the Games," WHO said, urging those who are attending to protect themselves against mosquito bites and also practice safe sex.
Tuesday's new warning, acknowledging mounting evidence for Zika's likely sexual transmission, however, should give couples and potential new parents pause as they make travel plans.
"Substantial new research has strengthened the association between Zika infection and the occurrence of fetal malformations and neurological disorders," WHO said Monday, adding that "more investigation is needed to better understand the relationship."
WHO data from 2008 to 2016 found that 10 nations had reported sexual transmission of Zika. They included the U.S., France, Italy, Argentina, Chile, Peru, Portugal, New Zealand, Canada and Germany. It noted that in published research, transmission occurred from an infected male. The WHO added in its latest warning that previously infected males should wait six months before trying to conceive to allow the virus to fully leave their systems.
The U.S. Centers for Disease Control and Prevention, through its Zika Active Pregnancy Surveillance System, found that through May 19, a total of 279 pregnant women living in the U.S. and U.S. territories had tested positive for Zika. Those cases, the CDC noted, came from women with "laboratory evidence of possible Zika virus infection."
Dr. Jean Carstensen, a clinical instructor of internal medicine and pediatrics at the University of Michigan in Ann Arbor, says couples should pay attention as more is learned about the virus.
"One thing we don't know about Zika yet is penetrance; meaning, of people who get infected, how many will develop problems with pregnancy," Carstensen said, calling the WHO recommendations very conservative.
"I would add that if a couple is trying to conceive, and international travel to a Zika endemic area is unavoidable, then waiting eight weeks to attempt to conceive seems prudent," he said. "Because the effect of Zika on the developing fetus is so catastrophic, that avoidance seems wise."
As Zika epidemic concerns widen, lawmakers in Washington, D.C. are still wrangling over emergency funding to study and fight the virus. The House recessed May 26 without passing legislation on the Zika outbreak as it failed to get on the same page with Senate counterparts who had passed their own bill for about $1.1 billion devoted to Zika research, vaccine testing and also mosquito extermination. President Barack Obama had called on Congress for about $1.9 billion in Zika funding.