Zika Virus and Chikungunya in Pregnancy
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Direct answer
Zika virus infection in pregnancy can cause congenital Zika syndrome, with microcephaly, brain calcification and eye abnormalities in the fetus. Chikungunya is an alphavirus infection spread by Aedes mosquitoes, and maternal viraemia near delivery can transmit the virus to the newborn. Neither infection has an antiviral with proven benefit, so care is supportive and vector control is the main prevention.
What you must remember
- Transmission: both are spread by Aedes mosquitoes; Zika can also spread sexually, and chikungunya reaches the newborn mainly around delivery.
- Congenital Zika syndrome: microcephaly, brain calcification, eye abnormalities, joint contractures and hypertonia in affected infants.
- Zika diagnosis: RT-PCR on serum or urine during the acute phase, since IgM serology cross-reacts with dengue.
- Fetal assessment: serial ultrasound for brain and eye anomalies, with fetal MRI added in selected cases.
- Chikungunya in pregnancy: the maternal illness is usually self-limiting, but neonatal disease can be severe in infants exposed near delivery.
- Symptomatic care: paracetamol for fever and arthralgia, with aspirin and NSAIDs avoided until dengue has been excluded.
- Prevention: vector control, bed nets, repellents and advice on avoiding exposure in endemic areas.
A stepwise approach to a febrile pregnant woman
A pregnant woman with fever and rash who has recently returned from an endemic area needs an exposure history and the right samples at the first visit. The steps below keep the fetal assessment and the counselling in step with the laboratory results.
- Take the exposure history: travel to an endemic area, rash, conjunctivitis, arthralgia and recent sexual contact with a traveller narrow the differential.
- Send acute-phase samples: RT-PCR on serum and urine for Zika, with chikungunya and dengue testing run in parallel.
- Interpret serology carefully: IgM for Zika and dengue cross-react, so a single positive result does not confirm infection.
- Scan the fetus serially: growth and anatomy ultrasound look for brain and eye abnormalities, and fetal MRI can add detail.
- Counsel the couple: explain the risk of congenital Zika syndrome and the uncertain outcome in many cases, in a non-directive way.
- Alert the neonatal team: if maternal viraemia is present near term, paediatric review is arranged, while the mode of delivery stays on obstetric grounds.
Where the exam tries to catch you
Vignettes exploit cross-reactive serology and the reflex to perform caesarean, so the interpretation of the test is the point most often examined.
- Trap: Reading a positive dengue-type IgM as proof of Zika. Correct: Serology cross-reacts within the flavivirus group, so PCR and the clinical picture are needed for confirmation.
- Trap: Performing caesarean to prevent chikungunya transmission. Correct: Elective caesarean is not indicated solely to prevent vertical transmission, so obstetric indications decide.
- Trap: Giving aspirin for joint pain in a febrile woman. Correct: Paracetamol is preferred, and aspirin is avoided until dengue has been excluded because of bleeding risk.
Frequently asked questions
What are the features of congenital Zika syndrome?
Congenital Zika syndrome includes microcephaly, brain calcification, eye abnormalities, congenital contractures and hypertonia. Severity varies, and some infants have a near-normal head size at birth. Serial ultrasound and neonatal evaluation help track the infant.
How is Zika virus infection diagnosed in pregnancy?
Zika is diagnosed by RT-PCR on serum or urine during the acute phase. Zika IgM antibody testing is less specific because it cross-reacts with dengue, so results must be read with the clinical picture. Amniotic fluid PCR may be considered in selected cases.
Can chikungunya pass from mother to baby?
Chikungunya can pass from mother to newborn, usually when the mother is viraemic around the time of delivery. Neonatal illness can be severe, so the paediatric team should be alerted. Caesarean is not advised solely to prevent this transmission.
Which analgesic is safe for fever in a pregnant woman with chikungunya or dengue?
Paracetamol is the preferred analgesic for fever and joint pain in chikungunya or dengue during pregnancy. Aspirin and NSAIDs are avoided until dengue has been excluded, because of the bleeding risk. Clinicians should monitor platelet counts in febrile patients.