What Is Zika Virus?

Zika virus is a mosquito-transmitted infection that is present in some parts of the world. It is named after the Zika forest in Uganda, where the virus was first isolated in 1947. 

The virus is transmitted by infected mosquitoes in tropical and subtropical regions. Although the infection itself (sometimes called Zika fever) is usually mild and resolves on its own, the virus has significant effects on pregnant women and their infants. Some precautions can be taken to prevent Zika fever. Read more about Zika Virus below. 

Overview

Zika virus is a mosquito-borne virus that was first identified in Uganda's rhesus monkeys in 1947, followed by human infection and disease in other African countries in the 1950s. In February 2016, the Zika virus was declared a public health emergency of global concern by the World Health Organization (WHO). Since 2017, Zika infections have declined. However, Zika infection is still endemic and could cause large-scale outbreaks in some areas.¹

The disease is usually mild, with symptoms lasting up to a week. Many people experience no or only mild symptoms. In rare cases, the Zika virus can cause complications in the brain and nervous system, such as Guillain-Barré syndrome, even in people who show no symptoms of infection.

In addition, infection with the Zika virus during pregnancy can cause a serious birth defect called microcephaly (a condition where a baby's head is much smaller than expected) and other serious brain disorders.

Key facts:

• Symptoms of Zika virus are usually mild, with only 1 in 5 infected people developing symptoms. Hospitalisation for this infection is rare
• Zika fever can be diagnosed with a blood test
• The Centers for Disease Control and Prevention maintains an up-to-date list of countries with Zika outbreaks. Pregnant women should consult their healthcare provider if they travel to infected areas and need to take precautions to avoid mosquito bites
• There is currently no vaccine or antiviral treatment for Zika

Causes of zika virus

Zika virus is transmitted through the bite of an infected mosquito. It is mainly transmitted by two Aedes mosquito species, which are common in tropical and subtropical regions. Infected Aedes mosquitoes usually bite during the day, however, they can also be active during the night. Zika virus can also be transmitted between humans through sexual contact, blood and blood product transfusions, and possibly organ transplantation. Transmission can occur from mother to foetus during pregnancy and birth.¹

Signs and symptoms of zika virus

Commonly, people infected with the Zika virus do not manifest any symptoms. When they do occur, symptoms usually begin 3 to 14 days after infection. Mild symptoms can last between 2 and 7 days and include the following: 

• Rash
• Fever
• Conjunctivitis (red and swollen eyes)
• Muscle and joint pain
• A general feeling of being sick 
• Headache

However, these symptoms are also seen in other diseases. Therefore, diagnosis of Zika virus infection requires laboratory confirmation.

Management and treatment for zika virus

There is no specific treatment for Zika virus infection. People with symptoms should rest, stay hydrated, and treat symptoms with drugs that reduce fever and pain relievers. Nonsteroidal anti-inflammatory drugs increase the risk of bleeding and should be avoided until dengue virus infection is ruled out. If symptoms worsen, patients should seek medical attention and advice.

Pregnant women living in areas where Zika virus is endemic or wh develop symptoms of Zika virus infection should seek medical attention immediately.

FAQs

How is zika virus diagnosed?

To diagnose Zika virus infection, your doctor will ask about your medical and travel history. Therefore, you must include details of any international travel, including countries you and your sexual partner have visited, dates of travel, and whether you may have been exposed to mosquitoes.²

If your doctor suspects you have the Zika virus infection, you will be asked to have a blood or urine test to confirm the diagnosis. Blood or urine samples can also be used to test for other similar mosquito-borne diseases.²

If you are pregnant and have no symptoms of Zika virus infection, but you or your partner have recently travelled to an area with high Zika virus prevalence, then you should contact your doctor for further steps on how to prevent any complications.

How can I prevent zika virus?

Currently, no vaccine for Zika virus prevention has been developed, with vaccine development remaining an active research area.³ Yet, there are several ways to prevent the Zika virus:

Clothing: 

• Wear long-sleeved shirts and long pants

Use insect repellent: 

• Use Environmental Protection Agency (EPA)-registered insect repellents external with one of the following active ingredients: DEET, picaridin, IR3535, oil of lemon eucalyptus or para-menthane-diol. Always follow the product label instructions
• With appropriate use, evidence supports that insect repellents are safe and effective for pregnant and breastfeeding women
• Avoid using products with lemon eucalyptus oil or para-menthane-diol on children younger than 3 years old

At home:

• Stay in places with air-conditioning and window and door screens to keep mosquitoes outside
• For babies younger than 2 months old in carriers or beds, mosquito nets can be used to prevent infection
• Use a mosquito bed net while sleeping if air-conditioned or screened rooms are not available or if sleeping outdoors

Sexual transmission:

• Use condoms to prevent sexual transmission of Zika virus 

Who is at risk of zika virus infection?

People who live or travel to areas with a high prevalence of Zika virus infected mosquitoes are at a higher risk of getting infected. Zika virus is not endemic in the UK. Protective measures need to be taken if you are travelling to the following places:

• America 
• The Caribbean islands
• The Pacific islands
• Africa
• Asia

Pregnant women and zika virus

Zika virus infection during pregnancy can cause microcephaly and other birth defects in infants, such as:

• Limb deformities 
• Muscle stiffness
• Eye abnormalities 
• Loss of hearing 

These clinical features are collectively termed congenital Zika syndrome. 

It is estimated that 5-15% of infants who were born to infected mothers show signs of these complications. Congenital malformations can occur in cases where the mother has symptomatic or asymptomatic infections. Zika Infection during pregnancy can also lead to miscarriage, stillbirth, and premature birth.  Therefore, if you are pregnant, it is vital you consult with your doctor if you are about to travel, or have recently travelled, to a country where Zika virus is prevalent.

How common is the zika virus?

As of 2017, cases of Zika virus disease are declining worldwide. However, Zika virus transmission is still occurring at low levels in several countries. An estimated 3.6 billion people live in high risk areas.  In addition, the first local cases of mosquito-borne Zika virus disease was reported in Europe in 2019 and Zika virus outbreak activity was detected in India in 2021. To date, a total of 89 countries and territories have reported evidence of mosquito-borne Zika virus transmission.³ 

When should I see a doctor?

If you have symptoms of Zika virus infection(fever, rash, headache, joint pain, red eyes, muscle pain) and live in, or have recently travelled to a high-risk area, consult your doctor or healthcare provider. 

Summary

There is currently no vaccine nor specific antiviral drugs that target the Zika virus. As symptoms are often mild, they can often be managed with over-the-counter pain-killers. It is recommended that you wear long sleeves and long pants, and use mosquito repellent to minimise the risk of mosquito bites if you are in an area where Zika virus is endemic. 

Although Zika virus is no longer a public health emergency, transmissions and outbreaks still occur. Several challenges need to be addressed, including the development of specific drugs and vaccines, the need for improved epidemiological surveillance in areas at risk, and the identification of long-term effects of Zika infection, particularly infants.