As the weather begins to warm across the United States, the Centers for Disease Control and Prevention wants pediatricians to know how to recognize, diagnose, and treat Zika virus infection.
Zika virus has been blamed for as many as 5000 cases of microcephaly in Brazil, and while it’s not being spread locally throughout US states at this time, the Centers for Disease Control and Prevention (CDC) is urging pediatricians to familiarize themselves with the virus to help educate patients about the risks.
Sonja A Rasmussen, MD, MS, director of the division of Public Health Information and Dissemination for the Centers for Disease Control and Prevention, editor-in-chief of CDC’s Morbidity and Mortality Weekly Report, says new guidance released by CDC is a review of what is currently known about Zika as it pertains to infants and children. The CDC authors describe Zika virus; how it’s transmitted; its epidemiologic characteristics; clinical presentation; laboratory testing; treatment; and prevention.
“Because pediatricians might be caring for women who are pregnant or who might be thinking about becoming pregnant, we also wanted to be sure they were aware of the link between Zika virus during pregnancy and microcephaly, other serious problems of the brain, and other problems in pregnancy,” Rasmussen says. “The CDC recommends special precautions for pregnant women. Women who are pregnant should not travel to areas with active Zika virus spread. Pregnant women with male sex partners who have lived in or traveled to an area where Zika virus is spreading should either use condoms every time they have sex or not have sex during the pregnancy.”
Since news of the Zika virus broke, some media outlets were reporting that pesticides used to control mosquitoes in some South American countries-not the virus itself-was responsible for microcephaly, but that theory was recently debunked.
Rasmussen says there is mounting evidence to suggest that Zika is indeed responsible for microcephaly and other serious brain defects.
“Recent reports in the media suggested that a pesticide called pyriproxyfen might be linked with microcephaly. Pyriproxyfen has been approved for the control of disease-carrying mosquitoes by the World Health Organization (WHO). Pyriproxyfen is a registered pesticide in Brazil and other countries and has been used for decades. There is no evidence that it is linked with microcephaly or other problems during pregnancy,” Rasmussen says. “In addition, exposure to pyriproxyfen would not explain recent study results showing the presence of Zika virus in the brains of babies born with microcephaly.”
The Zika virus was first identified in a monkey in Uganda in 1947 and has been found since then along the equator throughout Africa and Asia. It is spread by the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus), which also transmit dengue and chikungunya viruses.
About a decade ago, cases started appearing throughout the Pacific Islands, and the first case in the Americas was reported in Brazil in mid-2015. Since then, the mosquito-borne disease has spread to 22 other countries and regions in the Americas, according to the WHO, and may have been the cause of up to 5000 cases of microcephaly since 2015.
The CDC is now reporting 346 cases of travel-associated Zika cases in US states, and no locally acquired cases. Thirty-two of the cases were among pregnant women; 7 were sexually transmitted; and 1 individual had Guillain-Barré syndrome. Locally acquired cases have occurred in US territories, according to CDC, including Puerto Rico, the US Virgin Islands, and American Samoa.
H Cody Meissner, MD, FAAP, a member of the American Academy of Pediatrics Committee on Infectious Disease and chief of the division of pediatric infectious disease at Tufts Medical Center in Boston, Massachusetts told Contemporary Pediatrics in January that he expects Zika virus to be endemic in the United States by summer, as temperatures rise across the majority of the nation.
About 20% of individuals infected with the Zika virus develop symptoms, which can include high fever, joint pain, rash, conjunctivitis, muscle pain, and headache.
The CDC says the incubation period for the virus is most likely between a few days and a week. The illness is usually mild, with severe illness resulting in hospitalization and death occurring rarely. No medications or treatments are available aside from comfort care such as rest, hydration, and pain relief. However, the larger risk is to the unborn children of pregnant women.
Children born to women who are infected with Zika virus are believed to suffer from a congenital infection of the virus, which can result in serious, irreversible birth defects.
Fetal ultrasounds and maternal blood testing for the virus can be helpful in making a diagnosis, although the maternal blood test can easily yield false positives. The CDC recommends that Zika testing be performed on any infant with microcephaly or intracranial calcifications born to women who live in or have traveled to an area where Zika is endemic, and also on infants whose mothers had positive or inconclusive test results for Zika. When infants are born with microcephaly or intracranial calcifications, the infant and mother should both be tested for Zika infection. The infant should also receive an ophthalmologic evaluation within the first month of life, and a hearing screen at 6 months even if the initial hearing screen was normal.
Infants and children who are at-risk of contracting the virus due to travel or exposure and who display possible symptoms should undergo Zika testing, says CDC, and any cases that are confirmed must be reported.
Zika diagnoses can be made through molecular and serologic testing including reverse transcription-polymerase chain reaction (RT-PCR) for viral RNA, and immunoglobulin (Ig) M ELISA and plaque reduction neutralization test for Zika virus antibodies, according to CDC.
Zika RT-PCR tests should be performed on serum specimens collected from the umbilical cord, cerebrospinal fluid, frozen and fixed placenta obtained at delivery, or certain other bodily fluids. The IgM ELISA testing is also an option, but can yield false positives as a result of cross-reacting antibodies. Immunohistochemical staining to detect Zika virus antigen on fixed placenta and umbilical cord tissues can be performed, says CDC.
The CDC considers an infant to be congenitally infected if Zika virus RNA or viral antigen is found in any of the samples tested.
When evaluating for possible congenital Zika virus infection, the CDC defines microcephaly as an occipitofrontal circumference of less than the third percentile based on standard growth charts.
There is no vaccine against the Zika virus, and treatment is supportive only, says CDC. Children seem to be affected by the virus less frequently than adults, and symptoms can mimic a host of common childhood illnesses.
Pediatricians can treat the symptoms of the virus with acetaminophen and antihistamines, but aspirin is not recommended due to the risk of Reye’s syndrome in children. Also, nonsteroidal anti-inflammatory drugs are not currently recommended as a first line treatment for symptoms until Dengue fever is ruled out due to a possible hemorrhagic complication in individuals infected with the dengue virus, which is carried by the same mosquitoes that spread Zika.