ZIKA VIRUS: Pregnancy and complications- important notes for health care professionals

Zika infection, an emerging mosquito-borne virus is prompting worldwide concern for global health agencies due to its rapid spread and worrying connection to neurological birth disorders. According to Margaret Chan, the World Health Organization (WHO) Director-General "The level of alarm is extremely high."

Epidemiology

The virus is transmitted to humans through Aedes mosquitoes bites. It is a single-stranded RNA virus of the Flaviviridae family, genus Flavivirus. Zika virus was first isolated in 1947 from rhesus monkeys and subsequently identified in humans 1952 in Uganda and Tanzania. The name comes from Zika forest in Uganda.

Aedes species mosquito also transmit dengue and chikungunya viruses. Aedes species usually bite during the morning and late afternoon/evening hours.

Mode of transmission

1. Perinatal, in utero (Rarely)

• In rare cases, a mother already infected with Zika can pass on the virus to her newborn at time of delivery.
• It is possible that transmission could occur from mother to fetus during pregnancy.
• No reports of Zika virus transmission through breastfeeding to infants. Infected mothers are thus still encouraged to breastfeed because of the benefits from breastfeeding.

2. Sexual or transfusion transmissionSpread of Zica virus through sexual contact and blood transfusion has been reported.

Who is at risk?

Anyone living in or visiting an area where the virus has been reported should be considered at risk and evaluated.

Nearly 1 in 5 people infected with Zika virus develop Zika. Outbreaks have been reported in Southeast Asia, Latin American countries, the Caribbean islands and the Pacific Islands.

Symptoms

Clinical findings commonly reported include acute onset of fever with maculopapular rash, arthralgia, or conjunctivitis. Other usually reported symptoms include muscle ache and headache.
Clinical illness is generally mild with symptoms lasting several days to a week. Need for hospitalization is rare with low fatality course.

Diagnosis

The virus can be isolated in the blood for few days following infection or longer.

Zika virus diagnosis is done through PCR (polymerase chain reaction) and virus isolation from blood samples.

Zika viruses cross-react with other flaviviruses such as dengue, West Nile and yellow fever making serology testing tedious. 

Laboratory testing

If laboratory testing is needed, the following order should be made:

• IgM, IgG and PCR for Zika virus
• Acute serum (taken within 5 days of symptom onset) and convalescent serum (2–3 weeks later) should be taken.

The two samples are important to rule out false positive tests due to cross reactivity with similar viruses such as Dengue

Provide overseas travel details and clinical history including the onset day. Onset date is extremely vital to ensure most appropriate test is performed.

Treatment

No vaccine or medications are available to prevent or treat Zika infections. Treatment is generally supportive;

• Provide plenty of rest
• Encourage fluids intake to prevent dehydration
• Relieve fever and pain with medicine such as acetaminophen
• Avoid aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs), like ibuprofen and naproxen to reduce the risk of hemorrhage until dengue has be ruled out.
• Prevent mosquito bites in the first week illness to avoid spread of virus. 

Recommendations for Pregnant Women at risk of Zika Virus

These recommendations are applicable for screening, testing, and management pregnant women returning from Zika virus transmission areas or considering travel to those locations

• Report and test all pregnant women who report two or more symptoms consistent with Zika virus disease (acute onset of fever, maculopapular rash, arthralgia, or conjunctivitis) during or within 2 weeks of travel, or who have ultrasound findings of fetal microcephaly or intracranial calcifications
• Testing is not indicated for women without a travel history to an area with Zika virus transmission.
• Monitor fetal growth and anatomy in pregnant women with laboratory evidence of Zika virus infection
• There is no specific antiviral treatment for Zika virus; supportive care is recommended.
• Serial ultrasounds should be considered to monitor fetal anatomy and growth every 3–4 weeks in pregnant woman with laboratory evidence of Zika virus in serum or amniotic fluid.
• Refer  for expertise in pregnancy management to a maternal-fetal medicine or infectious disease specialist

Although incidence of Zika virus infection in pregnant women is currently unknown because of limited data infection can occur at any trimester. 

Complications in pregnancy

Zika virus infections have been associated with poor pregnancy outcomes and congenital malformations in new born infants; notably microcephaly, fetal losses, Guillain-Barré syndrome among others

The full spectrum of outcomes that might be associated with Zika virus infections during pregnancy is unknown and requires further investigation.

Zika virus testing in newborn

Zika virus RT-PCR and serology assays can be performed on infant serum or serum

Cerebrospinal fluid (CSF) specimens are considered only if available for PCR; however, CSF specimens should not be obtained for the sole purpose of Zika virus testing. Other testable specimens include blood samples from placenta and umbilical cord.

Histopathologic examination and immunohistochemical staining can be performed. Zika virus RT-PCR on fixed and frozen tissue should also be considered.

Community prevention strategies

• Wear long-sleeved shirts and long pants
• Use insect repellents containing DEET, picaridin, oil of lemon eucalyptus (OLE), or IR3535. Always use as directed. When used according to the product label they are safe for pregnant and nursing women and children older than 2 months Oil of lemon eucalyptus products should not be used on children under 3 years of age.
• If you use both sunscreen and insect repellent, apply the sunscreen first and then the repellent.
• Use permethrin-treated clothing and gear (such as boots, pants, socks, and tents).
• Use bed nets as necessary
• Stay and sleep in screened-in or air-conditioned rooms.

Reference:

• Besnard M, Lastère S, Teissier A, Cao-Lormeau VM, Musso D. Evidence of perinatal transmission of Zika virus, French Polynesia, Euro Surveill  2014;19(13):pii=20751.
• Zika Virus: Centers for Disease Control and Prevention - http://www.cdc.gov/zika/
• Zika virus (New Zealand Ministry of Health)
• The Zika Virus: What You Need to Know- White House update- https://www.whitehouse.gov/blog/2016/01/27/zika-virus-what-you-need-know
• Zika virus: WHO media centre- http://www.who.int/mediacentre/factsheets/zika/en/ Accessed January 30, 2016

By Collins