Zika Questions Abound, but Standard Precautions Will Stop it
With so many unknowns, CDC says protect pregnant, unborn
March 1, 2016
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By Gary Evans, Senior Staff Writer
The Zika virus outbreak spreading through the Americas is raising a host of questions for U.S. infection preventionists, who are trying to keep staff informed on the unfolding public health aspects while emphasizing that standard precautions and safe injection practices will prevent transmission in healthcare settings.
Though the primary threat is to pregnant women and unborn children, adherence to bedrock infection control measures should block transmission if patients with the mosquito-borne virus are hospitalized or treated in other healthcare settings.
“The most important thing from the infection prevention side is it really is back to the basics of standard precautions,” says Sue Dolan, RN, MS, CIC, hospital epidemiologist at Children’s Hospital (Aurora) Colorado and 2016 president of the Association for Professionals in Infection Control and Epidemiology (APIC). “Part of standard precautions is injection safety — that’s one of the key components. It’s not just personal protective equipment [PPE]. We need to make sure that [healthcare workers] are using the right equipment, that they are pausing and not rushing and being careful how they use devices.”
In that regard, a recently reported case of nosocomial transmission of malaria underscores how a mosquito-borne pathogen could be spread between hospitalized patients. A patient with no travel history developed malaria, which investigators eventually traced to another patient from Nigeria who was being treated for the disease. The suspected source was a contaminated glucometer, as both patients had blood sugar checks. Further investigation revealed that the glucometers were not routinely nor adequately cleaned after use.1
Though Zika is new to the Western Hemisphere after being discovered in Africa in 1947, the U.S. has faced other mosquito-borne threats and is all too familiar with bloodborne pathogens.
“There are other mosquito-borne diseases that we see occasionally in patients returning from travel and there are other bloodborne diseases that we know well — hepatitis B and C, HIV,” Dolan says. “We know how these are transmitted. The key is back to the basics with standard precautions including PPE and injection safety with our frontline staff.”
In addition to the use of gloves, gowns, and face masks depending on anticipated exposure, standard precautions emphasize hand hygiene, respiratory and cough etiquette, and safe handling of potentially contaminated equipment — for all patients.
“Another important thing is that a certain percentage [80%] of people with Zika do not exhibit symptoms,” Dolan says. “That is another good reason to use standard precautions. We don’t know who may have a virus or a disease that can be spread through bodily fluids or blood.”
QUESTIONS ON PREGNANCY, TRAVEL
Not surprisingly, IPs are getting Zika questions from staff about travel, transmission, and pregnancy, Dolan says.
“For example, ‘I’m traveling to this location or I am part of my mission with an outside organization and I may be pregnant or am attempting to become pregnant,’” she says. “In addition, there are questions about medical goodwill trips that are actually sponsored by hospitals, where staff go to these remote locations to provide surgeries, etc. First and foremost, I think the concern is about basic information with regard to transmission. As the evidence is unfolding, we are learning more about this and are advising individuals basically on the CDC recommendations around prevention of mosquito bites.”
As of February 9, 2016, more than 30 countries and territories, including the Commonwealth of Puerto Rico as well as the U.S. Virgin Islands and American Samoa, have reported local transmission of the Zika virus. In South America, Brazil has been particularly hard hit. On February 1, the World Health Organization (WHO) declared the recent clusters of microcephaly birth defects and Guillan-Barré paralytic syndrome were temporally linked with Zika virus transmission, making the outbreak a public health emergency of international concern.
As of Feb. 10, 2016, the CDC has reported 51 Zika infections in 17 U.S. states — 50 of them were travel related and one was a case of sexual transmission in Dallas. No cases of secondary transmission via mosquitoes had been reported at the time, but that was seen as inevitable. The U.S. cases include six pregnant women and the first reported birth of a baby with Zika-associated microcephaly, a defect that stunts the growth of the head and brain in the fetus. The woman traveled to Brazil early in her pregnancy and subsequently delivered an infant with microcephaly in Hawaii.
“Zika-associated microcephaly and other fetal harm are a new phenomenon,” CDC director Tom Frieden, MD, MPH, said at a recent press conference. “It has been more than 70 years since rubella was identified as a cause of fetal malformations. We are not aware of any prior mosquito-borne disease associated with such a potentially devastating birth outcome on a scale anything like what appears to be occurring with Zika in Brazil.”
Though the exact numbers await confirmation, a recent CDC report from Brazil said that between mid-2015 and January 2016, there were some 4,700 suspected cases of microcephaly. The investigators describe “evidence of a link between Zika virus infection and microcephaly and fetal demise through detection of viral RNA and antigens in brain tissues from infants with microcephaly and placental tissues from early miscarriages. Histopathologic findings indicate the presence of Zika virus in fetal tissues.”2
Zika is also suspected as the etiologic agent behind an increase in Guillain-Barré syndrome (GBS), an immune disorder that attacks the peripheral nervous system, causing weakness and tingling that can progress to almost total paralysis. A case count in the current outbreak has not been determined, but in a 2013-2014 outbreak of Zika virus in French Polynesia, 42 cases of GBS were detected, well above expected levels.
“With each passing day, the linkage between Zika and microcephaly becomes stronger,” Frieden said. “In addition, the linkage with Zika and Guillain-Barre syndrome also appears stronger the more we learn. And because it is new and because it is so severe, it is scary — especially for women who are pregnant or who are considering becoming pregnant.”
Moreover, there is “preliminary evidence”3 that microcephaly may be only the most visible Zika-related birth defect, as researchers are finding neurological lesions that may manifest more insidiously in newborns. This suggests there may be a spectrum of congenital harm caused by Zika infection during pregnancy.
“This is one of the key questions that we’ll be investigating in the coming days, weeks and months — because either possibility is there,” Frieden said. “On the one hand, it may be that many of the children who don’t have obvious microcephaly have significant health effects. On the other, it may be that if there isn’t [frank] microcephaly that children will have normal neural development. We just don’t know at this point.”
TESTING ISSUES
There are no commercially available diagnostic tests for Zika, so currently testing is being done at the CDC Arbovirus Diagnostic Laboratory and a few state or local health departments. Clinicians should contact their state or local health department to facilitate testing. As an arboviral disease, Zika virus is a nationally notifiable condition. Healthcare providers are encouraged to report suspected Zika cases to their state or local health department to facilitate diagnosis and mitigate the risk of local transmission.
“If we start seeing more of these cases admitted to healthcare facilities, certainly there are going to be medical management issues, which appear to be mostly at this time pediatric-related,” Dolan says. “[Microcephaly] is an illness we have seen in patients before, but not at the magnitude they are currently seeing in South America. But it is a condition that our providers are aware of. So the medical management of those patients and all the resources, the infrastructure that those families need, will be available in many locations that deal with children. There is also an urgency to have ready access to laboratory tests for diagnosis. We will need help from our state and CDC health partners on the mechanisms to submit the [specimens] for testing, with the idea being that testing will be brought in closer and closer to the state level through this process. So it is helpful to educate providers and staff about what is occurring now and what the plan is.”
The CDC recommends that pregnant women should avoid travel to areas where the virus is spreading and prevent mosquito bites through protective clothing and repellents if they are in such an area. Pregnant women without symptoms of Zika virus disease can be offered testing 2 to 12 weeks after returning from areas with ongoing Zika virus transmission, the CDC recommends. Information about serologic testing of asymptomatic persons is limited, but on the basis of experience with other flaviviruses, Zika antibodies may be present at 2 weeks after virus exposure and can persist for up to 12 weeks. Those with symptoms suggestive of Zika should, of course, be prioritized for testing. There is no vaccine or treatment for Zika.
The CDC recommends that men who reside in or have traveled to an area of active Zika virus transmission — and who have a pregnant partner — should abstain from sexual activity for the duration of the pregnancy or consistently and correctly use condoms during sex (i.e., vaginal intercourse, anal intercourse, or fellatio). Pregnant women should discuss their male partner’s potential exposures to mosquitoes and history of Zika-like illness with their healthcare provider.
Recommendations for Zika virus testing of pregnant women who have a clinical illness consistent with Zika virus disease during or within 2 weeks of travel to areas with ongoing Zika virus transmission are unchanged from those released January 19, 2016. Zika virus testing of maternal serum includes reverse transcription-polymerase chain reaction (RT-PCR) testing for symptomatic patients with onset of symptoms during the previous week; immunoglobulin M (IgM) and plaque-reduction neutralizing antibody testing should be performed on specimens collected ≥4 days after onset of symptoms.
The CDC recommends that women of reproductive age in areas where Zika transmission is occurring should discuss strategies to prevent unintended pregnancy with their doctors. This should include counseling on family planning and the correct and consistent use of effective contraceptive methods. CDC recommendations for pregnant women who live in areas with ongoing Zika virus transmission include the following:
- For those experiencing symptoms consistent with Zika, testing should be done at time of illness.
- For those not experiencing Zika symptoms, testing is recommended when they begin prenatal care.
- Follow-up testing around the middle of the second trimester of pregnancy is also recommended, because of an ongoing risk of Zika virus exposure.
- Pregnant women should receive routine prenatal care, including an ultrasound during the second trimester of pregnancy. An additional ultrasound may be performed at the discretion of the healthcare provider.
THE UNKNOWNS
There are many questions about transmission, but the thinking at the time of this report was that people who are asymptomatically infected with Zika can transmit the virus via mosquitoes during the approximately 1 week period it is circulating in the blood. Indeed, only about 20% of those infected with the virus will become symptomatic with the typical presentation of fever, rash, joint pain, and conjunctivitis. Symptoms of Zika virus infection have typically been mild and brief, with very low hospitalization and fatality rates. However, Brazil researchers have linked three adult deaths to Zika virus infections, including a 20-year-old woman who died of respiratory probems.4 As with other infections, comorbidities and immune deficiencies may contribute to more serious and fatal Zika infections. In a case series of 30 patients in Puerto Rico, 2 25% presented for healthcare and 10% were hospitalized, with the latter being a higher rate than suggested in the historical accounts of outbreaks. (See related story in this issue.)
While the virus is thought to clear the blood in about a week, it has been detected in other body fluids and may persist in semen. A similar finding marked the aftermath of Ebola, as researchers found persistence of virus in so-called “immune privileged” sites. As underscored by a case recently reported in Dallas, Zika can be transmitted sexually and the CDC has issued recent guidelines in that regard. (See related story in this issue.)
The CDC projects that Zika outbreaks in the U.S. mainland may be relatively small and localized in part because of better housing construction, less crowding, regular use of air conditioning, use of window screens and door screens, and state and local mosquito control efforts that have helped to contain transmission of these mosquito-borne viruses in the past.
“We hope and expect that local transmission will not become widespread, but we will have to change our guidance as we learn,” Frieden said. Facing a complex set of emerging issues, he listed the following Zika “unknowns” in testimony before Congress:
- the nature of maternal-to-child transmission,
- what cofactors may play a part in various consequences of the virus,
- the relationship to microcephaly, Guillain-Barré and other sequelae,
- level of risk, including symptomatic vs. asymptomatic transmission, and
- duration of infectivity in semen.
Given the unknowns, the CDC is focusing on preventing Zika transmission to pregnant women and their unborn children via mosquito bites.
“We are prioritizing all of the work that we can do to protect pregnant women,” Frieden said at the press conference when reporters peppered him with questions about other potential risk groups and transmission by routes other than mosquitoes.
“We are still learning more about Zika virus and how it works in the body,” he continued. “I think it is important to emphasize that Zika is a mosquito-borne virus and the overwhelming majority of cases are spread by mosquitoes. There are unknowns — we don’t know how long that Zika virus can persist in semen. Studies are underway to look at that, but it will be weeks to months before we know more. Our priority here is to prevent pregnant women from becoming infected with Zika and for that reason spread by other routes and other populations is of much less concern because again — four out of five cases of Zika are asymptomatic and those that are symptomatic are generally mild.”
Editor’s note: The CDC has posted a wealth of information on Zika for healthcare providers at: http://www.cdc.gov/zika/hc-providers/index.html.
REFERENCES
- Lee EH, et al. Healthcare–associated transmission of Plasmodium falciparum in New York City. Infect Control Hosp Epidemiol 2016;37:113-115.
- Thomas DL, Sharp TM, Torres J, et al. Local Transmission of Zika Virus — Puerto Rico, November 23, 2015–January 28, 2016. MMWR Early Release 2016;65:1-6
- Sun, LH. Zika expert: ‘Microcephaly may just be the tip of the iceberg.’ Washington Post Feb. 9, 2016
- Phillips D, Miroff N. Brazil says a third adult has died of Zika. Washington Post. Feb. 11, 2016
The Zika virus outbreak spreading through the Americas is raising a host of questions for U.S. infection preventionists, who are trying to keep staff informed on the unfolding public health aspects while emphasizing that standard precautions and safe injection practices will prevent transmission in healthcare settings.
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