NEW YORK/JOAO PESSOA, BRAZIL/AUSTIN, TEXAS – U.S. health officials are investigating more than a dozen possible Zika infections that may have been spread through sex.
The 14 cases all involve men who visited areas with Zika outbreaks, and who many have infected their female sex partners, who had not traveled to those areas.
Zika virus is mainly spread by mosquito bites, and sexual transmission has been considered rare. There have been two reported cases, including a recent one in Texas, and at least two other reports of the Zika virus found in semen.
Mosquito-borne Zika outbreaks have erupted across most of Latin America and the Caribbean in the last year. So far, all the 82 Zika infections diagnosed in the U.S. have involved people who traveled to outbreak regions.
On Tuesday, the Centers for Disease Control and Prevention said the 14 possible cases of sexual transmission in the U.S. include two pregnant women whose infections have been confirmed. Tests have not been completed for their male partners.
In four other cases, preliminary tests indicate women were infected but confirmatory tests are pending. Eight other cases are still being investigated, according to a CDC statement.
The agency said there’s no evidence that women can spread the virus to their sex partners, but more research is needed.
In most people, Zika causes mild or no symptoms — fever, joint pain, rash and red eyes — that last about a week. But in Brazil, health officials are investigating a possible connection between the virus and babies born with brain defects and abnormally small heads.
The link hasn’t been confirmed but the possibility has prompted health officials to take cautionary steps to protect fetuses from the virus.
Research is also underway into a possible link between Zika infection and a paralyzing condition in adults called Guillain-Barre syndrome.
The CDC is advising men who have recently been to a Zika outbreak area to use a condom when they have sex with a pregnant women, or to abstain from sex during the pregnancy. It also has recommended that pregnant women postpone trips to more than 30 destinations with outbreaks. The CDC on Tuesday expanded its Zika travel advisory to two more places — the Marshall Islands, and Trinidad and Tobago.
There is no vaccine for Zika. Researchers are scrambling to develop one, as well as better diagnostic tests.
The Zika virus is mostly spread by the same kind of mosquito that transmits other tropical diseases, including dengue and chikungunya. That same mosquito is found in the Southern U.S. and officials expect they will eventually spread the virus, too. But they don’t expect to see major outbreaks.
The CDC recommends that all travelers use insect repellent while in Zika outbreak areas, and continue to use it for three weeks after travel in case they might be infected but not sick. That’s to prevent mosquitoes from biting them and possibly spreading Zika to others in the U.S.
U.S. and Brazilian health workers meanwhile knocked on doors in the poorest neighborhoods of one of Brazil’s poorest states Tuesday in a bid to enroll mothers in a study aimed at determining whether the Zika virus is really causing a surge in birth defects.
Eight teams each made up of three Brazilian health workers and a so-called disease detective from the Atlanta-based Centers for Disease Control and Prevention began the first day of more than a month of house calls hoping to enroll at least 100 mothers and babies born with microcephaly, which causes unusually small heads and brain damage.
The women are given an extensive questionnaire touching on everything from whether they used mosquito repellent during pregnancy to where they got their drinking water to how much the family makes.
The teams started in Joao Pessoa, the capital of Paraiba state, which is one of the epicenters of Brazil’s tandem Zika and microcephaly outbreaks. Over the course of the next four or more weeks, they’ll head farther afield, reaching out to mothers and babies in the hard-to-reach rural districts of one of Brazil’s poorest states.
For now, the teams are venturing through some of the poorest neighborhoods of the capital, where families cohabitants with the Zika-spreading Aedes aegypti mosquito and eke by on just a couple hundred dollars a month.
Earlier, Brazilian Health Minister Marcelo Castro said he is “absolutely sure” mosquito-borne Zika is responsible for the spike in cases of microcephaly. But with scant scientific literature published on the matter, some doctors in Brazil and elsewhere say there is not yet enough scientific data to prove the connection.
The popular “understanding is that Zika virus (is behind the microcephaly spike). How much of that is Zika virus is really one of the important goals of this study,” said Erin Staples, a Colorado-based epidemiologist who heads the CDC contingent in Paraiba state. “I do believe there is something occurring that is unique and knowable, but we really need to understand better, mostly so we can prevent this from happening to other generations.”
The health teams hope to recruit at least 130 babies with microcephaly and their mothers and two to three times that number of mothers and babies without the condition, all born in the same areas and at around the same time.
The researchers will take blood samples from mothers and babies that will be sent to labs in Brazil and the United States to test for Zika and dengue, a similar virus also transmitted by the Aedes aegypti mosquito. The idea is to determine whether mothers whose babies have microcephaly were infected with Zika and, if so, when during their pregnancies.
Teams will also be on the lookout for other factors that, possibly in conjunction with Zika, could be behind Brazil’s increase in microcephaly, such as a prior infection with dengue, toxoplasmosis or the ingestion of toxins.
“If we can provide some basic information or show a potential association, that will allow us another avenue of how do we prevent this and what do we need to do next,” Staples said.
At a training session Monday in the state capital of Joao Pessoa, the field teams rehearsed how they will reach out to families and discussed ethical concerns, including how to react to reticence from potential subjects and how many times it is OK to prick babies to try to draw blood.
The language barrier proved a stumbling block at the training session, with the Brazilians and Americans team members often resorting to pantomime as they ran through the scripts they are to recite to potential subjects in this Portuguese-speaking nation.
Priscila Leite, who leads the Health Ministry’s contingent, said she expects recruitment numbers to be high given the level of alarm about Zika in Brazil — particularly here in the northeast, the epicenter of the country’s Zika and microcephaly outbreaks.
“There is a lot of anxiety out there, and people really want to understand what’s going on,” she said.
In Paraiba alone, 56 cases of microcephaly have been confirmed since October and 423 suspected cases are under investigation, the Health Ministry says. In previous years, Brazil tended to average around 150 cases nationwide.
Skeptics have said microcephaly cases may have been greatly underreported in Brazil in the past because local health officials weren’t required to notify the Health Ministry about cases of the condition until November. They also note the microcephaly spike appears to be largely restricted to Brazil, with few cases reported in other countries with Zika outbreaks, such as neighboring Colombia.
But Staples said she tended to lean toward the Health Ministry’s view.
“I come from a pediatric infectious disease background and am also a mom, so looking at these children clinically, they were distinct from other congenital infections I’ve seen,” said Staples, who spent time in Brazil recently as part of a World Health Organization mission. “The scope and the size of the children who were presenting (microcephaly) at the same time, it really made it apparent to me that there was something unique happening in this situation.”
Two major Texas health centers have developed what they are calling the country’s first hospital-based, rapid test for the Zika virus that can produce results in a matter of hours, the hospitals said on Tuesday.
Researchers at Texas Children’s Hospital and Houston Methodist Hospital developed the test that detects the genetic material of the Zika virus, which can speed diagnosis and treatment, they said in a statement.
“With travel-associated cases of the Zika virus becoming more prevalent in the United States, coupled with the looming increase in mosquito exposure during spring and summer months, we must be prepared for a surge of Zika testing demand,” said James Versalovic, pathologist-in-chief at Texas Children’s and leader of test development team.
The test is designed to cut down on testing time, which can take days or even weeks. Typically the testing would be done by state health agencies equipped to do so or federal authorities such as the U.S. Centers for Disease Control of Prevention.
Work on the test started in January and it is available only at the two hospitals for now. But the researchers are looking at allowing others to tap into its testing.
“We are definitely supportive of labs bringing up the ability to test for Zika virus across the state,” Texas Department of State Health Services spokeswoman Carrie Williams said. The agency expects to augment its own testing abilities by the end of the week.
The Zika virus has been reported as having been transmitted by mosquito in Puerto Rico and the U.S. Virgin Islands, but in the continental United States the only cases reported so far are associated with travel abroad.
Brazil is worst hit in the current Zika outbreak, which has spread to more than 30 countries and territories, most of them in the Americas. The World Health Organization declared a global emergency over Zika this month, citing concerns that it may be linked to a birth defect called microcephaly, a condition marked by unusually small heads that can result in developmental problems.
Much remains unknown about Zika, including whether the virus actually causes microcephaly.
Texas Children’s Hospital is a not-for-profit health care organization affiliated with Baylor College of Medicine, while Houston Methodist comprises an academic medical center in the Texas Medical Center and six community hospitals serving the Greater Houston area, according to the hospitals’ websites.