What is Zika Virus? A Brief About Zika Virus

What is Zika Virus? A Brief About Zika Virus

The Zika virus is a mosquito-borne virus that was first identified in a Rhesus macaque monkey in Uganda in 1947, followed by evidence of infection and disease in humans in other African countries in the 1950s.

Human infections were detected sporadically across Africa and Asia from the 1960s to the 1980s. However, outbreaks of Zika virus disease have been reported in Africa, the Americas, Asia, and the Pacific since 2007.

Zika virus infection has been linked to an increased incidence of Guillain-Barré syndrome in outbreaks over the last decade. When the Zika virus first appeared in the Americas, with a large epidemic in Brazil in 2015, an association between Zika virus infection and microcephaly (smaller than normal head size) was first described; similar findings were found in French Polynesia after a retrospective review.

From February to November 2016, WHO declared microcephaly, other neurological disorders, and Zika virus a Public Health Emergency of International Concern (PHEIC), and the causal link between Zika virus and congenital malformations was quickly confirmed (1,2).

Outbreaks of Zika virus disease have been reported in most of the Americas and other areas where Aedes aegypti mosquitos are established. Infections were detected in travellers from active transmission areas, and sexual transmission of the Zika virus was confirmed as an alternative route of infection.

Cases of Zika virus disease have decreased globally since 2017, but transmission remains low in several countries in the Americas and other endemic regions. Furthermore, the first cases of Zika virus disease transmitted by mosquitos were reported in Europe in 2019, and Zika virus outbreak activity was detected in India in 2021. To date, 89 countries and territories have reported evidence of mosquito-borne Zika virus infection; however, global surveillance remains limited.

Symptoms

The majority of people infected with the Zika virus do not show any symptoms. Among those who do, symptoms usually appear 3-14 days after infection, are mild, and last 2-7 days. Because these symptoms are shared by other arboviral and non-arboviral diseases, a diagnosis of Zika virus infection requires laboratory confirmation.

Complications

Microcephaly and other congenital malformations in the infant are caused by Zika virus infection during pregnancy, including limb contractures, high muscle tone, eye abnormalities, and hearing loss. Congenital Zika syndrome refers to all of these clinical features.

The risk of congenital malformations following Zika virus infection during pregnancy is unknown; an estimated 5-15% of infants born to pregnant women infected with Zika virus have evidence of Zika-related complications (3).

Both symptomatic and asymptomatic infection can result in congenital malformations. Infection with Zika during pregnancy can also result in complications such as foetal loss, stillbirth, and premature birth.

Infection with the Zika virus can also result in Guillain-Barré syndrome, neuropathy, and myelitis, especially in adults and older children.

There is ongoing research into the risk and effects of Zika virus infection on pregnancy outcomes, prevention and control strategies, and the effects of infection on other neurological disorders in children and adults.

Transmission

In tropical and subtropical areas, the Zika virus is primarily transmitted by infected mosquitos of the Aedes (Stegomyia) genus, particularly Aedes aegypti. Aedes mosquitos bite most often during the day. These mosquitos also spread dengue fever, chikungunya, and urban yellow fever.

The Zika virus is also passed from mother to foetus during pregnancy, as well as through sexual contact, blood and blood product transfusion, and possibly organ transplantation.

Diagnosis

Infection with Zika virus may be suspected based on symptoms of people living in or visiting areas with Zika virus transmission and/or Aedes mosquito vectors. A diagnosis of Zika virus infection can only be confirmed by laboratory tests of blood or other body fluids, and it must be distinguished from cross-reactive related flaviviruses such as dengue virus, to which the patient may have been exposed or previously vaccinated.

Treatment

There is currently no treatment for Zika virus infection or disease.

People experiencing symptoms such as rash, fever, or joint pain should rest, drink plenty of fluids, and seek treatment with antipyretics and/or analgesics. Because of the risk of bleeding, nonsteroidal anti-inflammatory drugs should be avoided until dengue virus infections are ruled out. Patients should seek medical attention and advice if their symptoms worsen.

Pregnant women who live in Zika-infected areas or who develop Zika-related symptoms should seek medical attention for laboratory testing, information, counselling, and other clinical care.

Prevention

There is currently no vaccine available for the prevention or treatment of Zika virus infection. The development of a Zika vaccine is still a work in progress.

Mosquito bit

Preventing mosquito bites during the day and early evening is a critical step in preventing Zika virus infection, particularly in pregnant women, women of reproductive age, and young children.

Wearing clothing (preferably light-coloured) that covers as much of the body as possible; using physical barriers such as window screens and closed doors and windows; and applying insect repellent to skin or clothing that contains DEET, IR3535, or icaridin according to product label instructions are all examples of personal protection measures.

If sleeping during the day or early evening, young children and pregnant women should use mosquito nets. Travellers and residents in affected areas should take the same basic precautions described above to avoid mosquito bites.

Aedes mosquitoes breed in small pools of water near homes, schools, and workplaces. It is critical to eliminate mosquito breeding sites, which include covering water storage containers, removing standing water in flowerpots, and cleaning up trash and used tyres.

Community initiatives are critical in assisting local governments and public health programmes in reducing mosquito breeding sites. Health officials may also recommend the use of larvicides and insecticides to reduce mosquito populations and disease spread.

Sexual transmission prevention

In areas where the Zika virus is actively spreading, all people infected with the virus and their sexual partners (particularly pregnant women) should be informed about the risks of Zika virus sexual transmission.

The World Health Organization recommends that sexually active men and women be counselled and offered a full range of contraceptive methods so that they can make an informed decision about whether and when to become pregnant in order to avoid potentially harmful pregnancy and foetal outcomes.

Women who have had unprotected sex and do not want to become pregnant due to Zika virus infection should have easy access to emergency contraception and counselling. Pregnant women should engage in safer sex (including the proper and consistent use of condoms) or refrain from sexual activity for the duration of their pregnancy.

For regions with no active Zika virus transmission, WHO recommends safer sex or abstinence for three months for men and two months for women returning from areas with active Zika virus transmission to prevent infection of their sex partners.

Sexual partners of pregnant women who live in or return from areas where the Zika virus is locally transmitted should practise safer sex or refrain from sexual activity during pregnancy.

The WHO’s response

WHO assists countries in conducting arbovirus surveillance and control through the implementation of the Global Arbovirus Initiative, which aligns with and expands on recommendations outlined in the Zika Strategic Response Plan.

The World Health Organization is responding to Zika in the following ways:

1. assisting countries in the confirmation of outbreaks through its collaborative laboratory network;
2. providing countries with technical assistance and guidance for the effective management of mosquito-borne disease outbreaks;
3. examining the creation of new tools, such as insecticide products and application technologies;
4. developing evidence-based strategies, policies, and plans for outbreak management

• providing technical assistance and guidance to countries for effective case and outbreak management;
• assisting countries in improving their reporting systems
• providing regional training in clinical management, diagnosis, and vector control in collaboration with some of its collaborating centres; and
• Member States will receive guidelines and handbooks on epidemiological surveillance, laboratory testing, clinical case management, and vector control.

Important information:

1. The Zika virus is primarily transmitted by Aedes mosquitos, which bite primarily during the day.
2. Most people infected with the Zika virus do not develop symptoms;
3. those who do typically have rash, fever, conjunctivitis, muscle and joint pain, malaise, and headache that last 2-7 days.
4. Infection with the Zika virus during pregnancy can result in microcephaly and other congenital malformations, as well as preterm birth and miscarriage.
5. In adults and children, Zika virus infection is linked to Guillain-Barré syndrome, neuropathy, and myelitis.
6. The WHO declared Zika-related microcephaly a Public Health Emergency of International Concern (PHEIC) in February 2016, and the causal link between the Zika virus and congenital malformations was confirmed.
7. In November of the same year, WHO declared the end of the PHEIC.
8. Although cases of Zika virus disease have decreased globally since 2017, transmission remains low in several countries in the Americas and other endemic regions.