The US Centers for Disease Control and Prevention (CDC) today released interim guidance on Zika virus for clinicians with pregnant patients returning from or considering visiting countries where it is circulating, a move that comes on the heels of its Jan 15 travel advice for pregnant women and those trying to conceive.
The CDC's warning a few days ago—urging pregnant women and those planning pregnancies to temporarily shelve their travel plans—was underscored by an announcement only hours later of a microcephaly case in a baby born in Hawaii.
Today's guidance for clinicians and the stepped-up travel advisory from a few days ago come during the winter vacation travel season to tropical climates and ahead of Brazil's pre-Lenten Carnival celebrations next month and the Summer Olympics that get under way in August.
Meanwhile, the Pan American Health Organization (PAHO) said the mosquito-borne virus has expanded its reach, which came with a request for countries to look for unusual rises in cases of Guillain-Barre syndrome (GBS), and officials in Brazil announced funding to fast-forward vaccine development.
Health provider guidance
The CDC published its interim guidance today in an early-release report in Morbidity and Mortality Weekly Report (MMWR). Health providers should ask all pregnant women about recent travel, and test those with a history of travel to the affected areas who have two or more symptoms consistent with Zika virus infection within 2 weeks of travel or who have ultrasound findings suggesting fetal microcephaly (small head size) or intracranial calcification.
So far no commercially available test for Zika virus is available, with tests needing to be performed by the CDC and several state health departments.
For pregnant women with positive Zika virus tests, clinicians should consider serial ultrasound to monitor fetal growth and referral to an obstetrics or infectious disease specialist with expertise in pregnancy management.
Several questions remain about the Zika-microcephaly connection, as well as the range of outcomes for pregnant women infected with the virus, the CDC said.
The CDC specified testing steps for babies with known intrauterine Zika virus exposure, and it said it is developing guidance for treating infected infants.
Because there are no vaccines or treatments for the illness, all pregnant women should consider postponing travel to areas reporting ongoing Zika virus transmission, the CDC said. Those who must travel to the areas should take extra precautions to avoid mosquitoes during the entire day. The CDC said insect repellent use is safe for pregnant women when used according to label directions.
The CDC's level 2 travel warning—to practice enhanced precautions—that was initiated on Jan 15 applies to those traveling to 14 regions or countries where Zika virus transmission is occurring. The advisory is thought to be the CDC's first to recommend pregnant women avoid travel to a specific part of the world.
Spread by Aedes mosquitoes, Zika virus causes a relative mild illness that resembles dengue fever, but it has been linked to a surge in microcephaly cases in Brazil. Recent lab studies have strengthened the link between maternal Zika virus infections and microcephaly, but health officials have said more evidence is needed to show a definitive connection.
Until more is known and out of an abundance of caution, the CDC said pregnant women in any trimester should consider postponing travel to Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname, Venezuela, and Puerto Rico. The CDC urged pregnant women who must travel, as well as those trying to get pregnant, to talk to their health providers in advance and strictly follow recommended steps to avoid mosquito bites.
Because of the rapidly evolving situation and unknowns about the transmission area, the CDC said it will update the travel advisory when it has more information. Travelers should follow the CDC's Web site closely for updated recommendations, the agency said. The CDC had already issued a level 1 travel notice for the affected areas, which urged pregnant travelers to take extra precautions to avoid mosquito bites.
The Public Health Agency of Canada (PHAC) on Jan 15 also issued a level 2 Zika virus travel notice, which encouraged pregnant women and those considering becoming pregnant to talk to their health providers about any plans to travel to the affected areas and to consider postponing their trips.
Hawaii microcephaly case
Shortly after the travel announcements, the Hawaii State Department of Health (HDOH) announced a Zika-linked microcephaly case, in a baby born to a mother who was likely infected with Zika virus while she lived in Brazil in 2015. State officials said CDC tests on samples from the baby, born at an Oahu hospital, and the mother suggest that both had been exposed to the virus, and that the baby was probably infected while in the womb.
The case is the first known Zika-linked microcephaly case in the United States.
Hawaii officials added that neither the mother nor the baby is currently infectious and that there was never a risk of transmission in Hawaii. No local transmission has been reported in Hawaii, though since 2014 the state has recorded six cases linked to travel in other countries. Infected returning travelers can transmit the virus to local Aedes mosquito populations.
Sarah Park, MD, Hawaii's state epidemiologist, said authorities are saddened by the infections in the mother and baby.
"This case further emphasizes the importance of the CDC travel recommendations released today. Mosquitos can carry serious diseases, as we know too well with our current dengue outbreak," she said, adding that an astute physician recognized the possible Zika link to the microcephaly case and immediately notified the HDOH.
PAHO: Zika in 18 countries, GBS rise
Meanwhile, PAHO said in a Jan 17 update that Zika virus is now circulating in 18 countries and territories in the Americas. In addition to the 14 locations noted by the CDC, PAHO said local transmission has also been reported in Barbados, Ecuador, Guyana, and St. Martin.
The agency also said it is investigating an unusual rise in GBS in some of the affected countries. A possible link between GBS and Zika virus infection was reported in the wake of an outbreak in French Polynesia in 2014.
PAHO said that since last July Brazil has been reporting neurologic complications in some patients who had recent Zika infection. Authorities in El Salvador this month reported an unusual increase in GBS since early December, according to PAHO. Typically the country reports 14 GBS cases per month, but from Dec 1 to Jan 6 it recorded 46 cases, 2 of them fatal. Of 22 patients with available information, 12 had been sick with a febrile rashlike illness 7 to 15 days before the onset of GBS symptoms.
Other countries in the Americas are reporting similar patterns, and investigations are under way, PAHO said. It also urged countries to look for other neurologic conditions reported by French Polynesia in its outbreak, which included meningitis, meningoencephalitis, and myelitis.
Also, PAHO described ocular problems affecting the macular area with loss of foveal reflex in three microcephalic babies from Brazil who had presumed intrauterine Zika virus exposure. One had well-defined macular neuroretinal atrophy.
Brazil to speed up vaccine development
In its latest step in the Zika battle, Brazil's health ministry on Jan 15 announced funding to develop a vaccine against Zika virus "in record time," according to a Jan 16 Associated Press (AP) story.
Jorge Kalil, MD, PhD, director of the Butantan Institute, which received the funding, predicted that it could take 3 to 5 years to develop a vaccine, the AP said.
In other developments, a program to control Aedes populations through the release of genetically modified mosquitoes is expanding in a part of Brazil, after showing promising results. Oxitec, based in Oxford, England and Germantown, Md., said in a press release today that, because of increased demand based on results from a project in Piracicaba, Brazil, it will launch a new mosquito production facility in that southern city that has the potential to protect as many as 300,000 people. The city is in Sao Paulo state.
The country's government has already approved release of the genetically modified mosquitoes, and a project to reduce A aegypti mosquito populations began in part of the city in April 2015, Oxitec said.
Jan 19 MMWR report
Jan 15 CDC press release
Jan 15 PHAC travel health notice
Jan 15 HDOH press release
Jan 17 PAHO epidemiologic update
Jan 16 AP story
Jan 19 Oxitec press release