Prevention and Management of In Utero Transmission of Vector-Borne Diseases

Prevention Strategies for Pregnant Women

Pregnant women in areas with vector-borne disease transmission should use insect repellent on skin and clothing, wear protective clothing, and avoid outdoor activities during peak mosquito-feeding times to prevent in utero transmission of diseases like malaria, Zika, and West Nile virus 1, 2, 3
Apply EPA-approved insect repellent to exposed skin and clothing when in areas with vector-borne disease transmission 2, 4
Wear long-sleeved shirts, long pants, and closed shoes to minimize skin exposure to mosquito bites 4, 3
Avoid outdoor activities during peak mosquito-feeding times, particularly dawn and dusk 2, 4
Screening of asymptomatic pregnant women for vector-borne diseases is not recommended due to lack of specific treatments and unclear consequences of infection 2, 3

Test pregnant women with meningitis, encephalitis, acute flaccid paralysis, or unexplained fever in areas with ongoing vector-borne disease transmission for specific antibodies in serum and CSF 2, 3
Report confirmed infections to local or state health departments for surveillance and follow-up of pregnancy outcomes 1, 5
For West Nile virus, serologic testing for virus-specific IgM and IgG antibodies in serum and/or CSF is the primary diagnostic method 3

Perform detailed ultrasound examination of the fetus to evaluate for structural abnormalities 2-4 weeks after onset of vector-borne illness (e.g., WNV) 2, 5
Consider testing amniotic fluid, chorionic villi, or fetal serum for evidence of infection, though sensitivity and specificity of these tests may be limited 2, 6
In case of miscarriage or induced abortion, test all products of conception (placenta, umbilical cord) for evidence of infection to document effects on pregnancy outcome 2, 4

Perform comprehensive clinical evaluation of infants born to mothers with confirmed vector-borne disease during pregnancy 2, 6
Test infant serum for antibodies to the specific pathogen 5, 3
Consider further evaluation if clinical abnormalities are identified or laboratory testing indicates congenital infection 2, 4

One case has demonstrated intrauterine WNV transmission resulting in chorioretinitis and cerebral tissue damage, though causal relationship is not definitively proven 5, 6
No specific treatment exists for WNV infection; management is primarily supportive care 3

The Centers for Disease Control and Prevention recommends treating clothing and gear with 0.5% permethrin, not exposed skin areas, to provide long-lasting protection through multiple washes, and avoiding outdoor activities during peak mosquito-feeding times, particularly dawn and dusk, as Aedes mosquitoes have peak feeding periods after sunset and after midnight 7
Pregnant travelers should stay in accommodations with air conditioning, screens, or bed nets to reduce indoor mosquito exposure 7

Only a portion of pregnant U.S. women who traveled to outbreak areas reported frequently using mosquito repellent, highlighting the need for meticulous adherence to all prevention measures, as supported by evidence from the BMJ 8