Zika Virus Disease: Clinical Signs, Complications and Congenital Infection

The main points

• About 80% of people infected with Zika virus have no symptoms.
• Illness is usually mild: fever, joint pain (arthralgia), conjunctivitis and a flat or raised red rash (maculopapular).
• Complications are rare but include Guillain-Barré syndrome, encephalopathy, myelitis, uveitis and low platelets (thrombocytopenia).
• Infection during pregnancy can cause congenital Zika infection, with serious birth defects of the brain and eyes.

A Zika virus rash on a patient's back. Image from CDC's page.

Clinical features

• Incubation: 3 to 14 days.
• Typical findings: sudden fever with a maculopapular rash, joint pain or non-pus-forming conjunctivitis. Muscle pain and headache are also common.
• Course: usually mild, lasting several days to a week.
• Severe disease needing hospitalization is uncommon, and fewer than 1% of cases are fatal. But Guillain-Barré syndrome has followed Zika infection, and, rarely, encephalopathy, meningoencephalitis, myelitis, uveitis and severe thrombocytopenia occur.

Infection in pregnancy

Zika in pregnancy can cause a congenital infection with serious defects of the brain and eyes: severe microcephaly, calcium deposits in the brain, brain atrophy, and abnormalities of the retina and choroid and of the optic nerve. It can pass to the fetus whether or not the mother has symptoms.

Babies with congenital infection may look healthy at birth yet have findings on brain imaging, or problems such as vision loss found only later. Fetuses and infants of women infected during pregnancy should be evaluated for congenital infection with brain and eye abnormalities. CDC's guidance on infants with possible congenital Zika infection covers diagnosis, evaluation and management.

Around delivery. Because the virus can pass from mother to baby during delivery, consider Zika in an infant who:

• has fever, rash, conjunctivitis or joint pain in the first 2 weeks of life, and
• whose mother may have been exposed within about 2 weeks of delivery.

Joint pain is hard to spot in infants and young children. It can show as irritability, difficulty moving or refusing to move a limb, pain when touched, or pain when the joint is moved.

Assessment

The typical features overlap with many infections, so the differential diagnosis is broad: besides dengue, consider leptospirosis, malaria, rubella, measles, and infection with parvovirus, enterovirus, adenovirus, rickettsia, group A strep, and alphaviruses such as chikungunya, Mayaro, Ross River, Barmah Forest, o'nyong-nyong and Sindbis.

A preliminary diagnosis rests on the patient's symptoms, where and when they traveled, and activities. Laboratory diagnosis generally tests whole blood, serum or plasma for the virus, its genetic material, or specific immunoglobulin M and neutralizing antibodies; for pregnant patients, urine testing for viral genetic material may also be recommended.

Sources

Based on "Clinical Signs and Symptoms of Zika Virus Disease," Zika Virus, for health care providers, Centers for Disease Control and Prevention; a work of the United States government in the public domain.