Congenital Zika virus infection
The virus was initially isolated in a monkey in Uganda, and human infection or serologic evidence of infection has been seen in India and other Asian countries. There was a major outbreak of Zika virus infection in Yap Island, Micronesia, in 2007. In 2015, Zika virus infection in Brazil was accompanied by an increase in the number of cases of microcephaly and intracranial calcifications seen in infants. There are also cases of fetal loss in women who were infected with Zika virus. It is thought that these outcomes are the result of congenital infection with Zika virus. Additionally, a study found that over 65% of infants with congenital Zika virus had onset of epilepsy at approximately 5 months of age.
Travel-related cases have been reported in the United States; however, since late 2016, Zika virus transmission in the Americas has dropped significantly.
Symptoms include fever, maculopapular rash, arthralgia, and conjunctivitis, although approximately 80% of patients infected with Zika virus are asymptomatic.
Newborns of women infected with Zika virus during pregnancy have a 5%-14% risk of congenital Zika syndrome. The risk is greatest when the mother is infected during the first trimester, although infection during any trimester can cause congenital Zika syndrome. First-trimester infection may also be associated with higher risks of pregnancy loss, preterm birth, and brain or eye defects in the infant.
Intrapartum transmission of Zika virus from an infected mother to her infant at the time of delivery has been described. Intrauterine transmission has also been described, and it is this mode of transmission that is thought to result in fetal loss or in fetal abnormalities including microcephaly, intracranial calcifications, and eye abnormalities (alterations in the macular region). Zika virus RNA has been identified in fetal tissue, placenta, and amniotic fluid in some cases. Zika virus RNA has been isolated from human breast milk, but transmission through breastfeeding has not been demonstrated. The Centers for Disease Control and Prevention (CDC) recommends testing for Zika virus in the following situations (Update: Interim Guidelines for the Evaluation and Management of Infants with Possible Congenital Zika Virus Infection – United States, August 2016):
- Infants born to mothers with laboratory evidence of Zika virus infection during pregnancy, and
- Infants who have abnormal clinical or neuroimaging findings suggestive of congenital Zika syndrome and a maternal epidemiologic link suggesting possible transmission, regardless of maternal Zika virus test results.
A92.8 – Other specified mosquito-borne viral fevers
3928002 – Zika virus disease
- Genetic causes – isolated genetic causes (eg, autosomal recessive microcephaly) or syndromic genetic causes (eg, trisomy 21)
- Infectious causes – TORCH infections (toxoplasmosis, rubella, cytomegalovirus, herpes, syphilis) and human immunodeficiency virus
- Teratogenic causes – eg, alcohol exposure
- Maternal causes – eg, malnutrition or hypothyroidism