Intrauterine West Nile virus infection--New York, 2002.

West Nile virus (WNV), a mosquito-borne flavivirus and human neuropathogen, is epidemic in the United States. In 2002, newly recognized mechanisms of person-to-person WNV transmission were described, including possible transmission from mother to infant through breast milk. WNV has not been previously associated with intrauterine infection or adverse birth outcomes. This report describes a case of transplacental WNV transmission. Pregnant women should take precautions to reduce their risk for WNV or other arboviral infection and should undergo diagnostic testing when clinically appropriate.

Interim guidelines for the evaluation of infants born to mothers infected with West Nile virus during pregnancy.

West Nile virus (WNV) is a single-stranded RNA flavivirus with antigenic similarities to Japanese encephalitis and St. Louis encephalitis viruses. It is transmitted to humans primarily through the bites of infected mosquitoes. Flavivirus infection during pregnancy has been associated rarely with both spontaneous abortion and neonatal illness but has not been known to cause birth defects in humans. During 2002, a total of 4,156 cases of WNV illness in humans, including 2,946 cases of neuroinvasive disease, were reported to CDC by state health departments. In 2002, a woman who had WNV encephalitis during the 27th week of her pregnancy delivered a full-term infant with chorioretinitis, cystic destruction of cerebral tissue, and laboratory evidence of congenitally acquired WNV infection. Although this case demonstrated intrauterine WNV infection in an infant with congenital abnormalities, it did not prove a causal relation between WNV infection and these abnormalities. During 2002, CDC investigated three other instances of maternal WNV infection. In all three cases, the infants were born at full term with normal appearance and negative laboratory tests for WNV infection; cranial imaging studies and ophthalmologic examinations were not performed. During 2003, CDC received reports of approximately 9,100 cases of WNV illness, including approximately 2,600 cases of neuroinvasive disease. CDC is gathering data on pregnancy outcomes for approximately 70 women with WNV illness during pregnancy.

Intrauterine West Nile virus: ocular and systemic findings.

PURPOSE: To report the first documented case of intrauterine transmission of West Nile virus (WNV) with resulting congenital chorioretinal scarring and central nervous system malformation in a newborn. DESIGN: Case report. METHODS: Ophthalmic findings and laboratory data in an otherwise presumed healthy 2-day-old female are presented. The infant's mother developed paraplegia due to WNV during the second trimester of her pregnancy. The newborn's external and general physical examination were unremarkable. RESULTS: Ophthalmic examination disclosed marked chorioretinal changes, and magnetic resonance imaging of the brain demonstrated severe abnormalities. Serology for WNV was positive. Other causes of congenital chorioretinal changes were ruled out with the appropriate serology. CONCLUSIONS: Intrauterine transmission of WNV may result in significant ocular and neurologic morbidity. Titers for this important and emerging viral pathogen should be obtained when standard serologies are negative in an infant with congenital chorioretinal scarring.

West Nile virus disease in children, United States, 1999-2007.

BACKGROUND: Although West Nile virus (WNV) disease has occurred predominantly among adults in the United States, children are also susceptible. Epidemiological data describing WNV disease in children are limited. METHODS: We described the epidemiological features of WNV disease among children (<18 years of age) reported to the Centers for Disease Control and Prevention from 1999 through 2007 and compared features of pediatric and adult West Nile neuroinvasive disease (WNND). RESULTS: Of 1478 pediatric WNV cases reported from 1999 through 2007, 443 (30%) were classified as WNND, 1009 (68%) were classified as West Nile fever, and 26 (2%) were of unknown clinical presentation. Three WNND cases were fatal. The vast majority of reported case subjects (92%) had onset of illness between July and September. Children accounted for only 4% of all of the WNND case subjects reported from 1999 to 2007, with a median annual incidence of 0.07 case subjects per 100 000 children (range: 0.00-0.19 case subjects). In children and younger adults WNND most often manifested as meningitis, in contrast to the predominance of encephalitis among older adults with WNND. The geographic distribution and temporal trends were of pediatric and adult WNND. CONCLUSIONS: The epidemiological characteristics of WNV disease in children are similar to adult case subjects; however, WNND is more likely to manifest as meningitis in children than in older adults. WNV should be considered in the differential diagnosis for pediatric patients presenting with febrile illness, meningitis, encephalitis, or acute flaccid paralysis, particularly during seasonal outbreaks in endemic areas.

Birth outcomes following West Nile Virus infection of pregnant women in the United States: 2003-2004.

BACKGROUND: Congenital West Nile virus (WNV) infection was first described in a single case in 2002. The proportion of maternal WNV infections resulting in congenital infection and clinical consequences of such infections are unknown. METHODS: In 2003 and 2004, women in the United States who acquired WNV infection during pregnancy were reported to the Centers for Disease Control and Prevention by state health departments. Data on pregnancy outcomes were collected. One of the maternal WNV infections was identified retrospectively after the infant was born. Maternal sera, placenta, umbilical cord tissue, and cord serum were tested for WNV infection by using serologic assays and reverse-transcription polymerase chain reaction. Infant health was assessed at delivery and through 12 months of age. RESULTS: Seventy-seven women infected with WNV during pregnancy were clinically followed in 16 states. A total of 71 women delivered 72 live infants; 4 women had miscarriages, and 2 had elective abortions. Of the 72 live infants, 67 were born at term, and 4 were preterm; gestational age was unknown for 1. Of 55 live infants from whom cord serum was available, 54 tested negative for anti-WNV IgM. One infant born with umbilical hernia and skin tags had anti-WNV IgM in cord serum but not in peripheral serum at age 1 month. An infant who had no anti-WNV IgM in cord blood, but whose mother had WNV illness 6 days prepartum, developed WNV meningitis at age 10 days. Another infant, whose mother had acute WNV illness at delivery, was born with a rash and coarctation of the aorta and had anti-WNV IgM in serum at 1 month of age; cord serum was not available. A fourth infant, whose mother had onset of WNV illness 3 weeks prepartum that was not diagnosed until after delivery, had WNV encephalitis and underlying lissencephaly detected at age 17 days and subsequently died; cord serum was not available. The following major malformations were noted among live-born infants: aortic coarctation (n = 1); cleft palate (n = 1); Down syndrome (n = 1); lissencephaly (n = 1); microcephaly (n = 2); and polydactyly (n = 1). One infant had glycogen storage disease type 1. Abnormal growth was noted in 8 infants. CONCLUSIONS: Of 72 infants followed to date in 2003 and 2004, almost all seemed normal, and none had conclusive laboratory evidence of congenital WNV infection. Three infants had WNV infection that could have been congenitally acquired. Seven infants had major malformations, but only 3 of these had defects that could have been caused by maternal WNV infection based on the timing of the infections and the sensitive developmental period for the specific malformations, and none had any conclusive evidence of WNV etiology. However, the sensitivity and specificity of IgM testing of cord blood to detect congenital WNV infection are currently unknown, and congenital WNV infection among newborns with IgM-negative serology cannot be ruled out. Prospective studies comparing pregnancy outcomes of WNV-infected and -uninfected women are needed to better define the outcomes of WNV infection during pregnancy.

West Nile virus infection among pregnant women in a northern Colorado community, 2003 to 2004.

OBJECTIVE: Since West Nile virus (WNV) was first detected in New York in 1999, it has spread across North America and become a major public health concern. In 2002, the first documented case of intrauterine WNV infection was reported, involving an infant with severe brain abnormalities. To determine the frequencies of WNV infections during pregnancy and of intrauterine WNV infections, we measured WNV-specific antibodies in cord blood from infant deliveries after a community-wide epidemic of WNV disease. METHODS: Five hundred sixty-six pregnant women who presented to Poudre Valley Hospital (Fort Collins, CO) for delivery between September 2003 and May 2004 provided demographic and health history data through self-administered questionnaires and hospital admission records. Umbilical cord blood was collected from 549 infants and screened for WNV-specific IgM and IgG antibodies with enzyme-linked immunosorbent assays, with confirmation by plaque-reduction neutralization tests. Newborn growth parameters, Apgar scores, and hearing test results were recorded. RESULTS: Four percent (95% confidence interval: 2.4-5.7%) of cord blood samples tested positive for WNV-specific IgG antibodies. No cord blood samples were positive for WNV-specific IgM antibodies. There were no significant differences between infants of seropositive and seronegative mothers with respect to any of the growth parameters or outcomes measured. CONCLUSIONS: Intrauterine WNV infections seemed to be infrequent. In our study, WNV infection during pregnancy did not seem to affect adversely infant health at birth. Larger prospective studies are necessary to measure more completely the effects of maternal WNV infection on pregnancy and infant health outcomes.