Dr. Arifa Akram BarnaMBBS MD(VIROLOGY)

Department of VirologyInstitute of Epidemiology, Disease Control and Research (IEDCR), DHAKA.

Zika is a virus spread by mosquitoes, which can cause fever, rash, joint pain, and conjunctivitis (red or pink eyes). Most people infected with Zika virus do not even get sick.

Virology

Zika virus belongs to the Flaviviridae and the genus Flavivirus, and thus related to dengue, yellow fever, Japanese encephalitis, and West Nile viruses.

Zika virus is enveloped and icosahedral and has a nonsegmented, single-stranded, positive-sense RNA genome.

What is Zika virus?

Structure

Countries reported Zika Virus

How Zika spread? Zika virus is transmitted to people primarily through the

bite of an infected Aedes species mosquito (A. aegypti and A. albopictus). These are the same mosquitoes that spread dengue and chikungunya viruses which can breed in a pool of water as small as a bottle cap and usually bite during the day.

pregnant mother who has been bitten by an infected mosquito to her baby during pregnancy or around the time of birth.

Recently, sexual transmission.

About 1 in 5 people infected become ill (i.e., develop Zika). The most common symptoms of Zika are fever, rash, joint

pain, or conjunctivitis (red eyes). Other common symptoms include muscle pain and

headache. The incubation period (the time from exposure to

symptoms) for Zika virus disease is not known, but is likely to be a few days to a week.

The illness is usually mild with symptoms lasting for several days to a week.

Deaths are rare.

Symptoms

The possibility that the Zika virus causes microcephaly – unusually small heads and damaged brains – emerged only in October”15, when doctors in northern Brazil noticed a surge in babies with the condition.

It may be that other factors, such as simultaneous infection with other viruses, are contributing to the rise; investigators may even find that Zika virus is not the main cause, although right now circumstantial evidence suggests that it is.

How might Zika cause brain damage in infants?

Babies with microcephaly have unusually small heads. But in the remainder of cases, the infant’s brain may not have developed

properly during pregnancy or may have stopped growing in the first years of life. These children may experience a range of problems, like developmental delays, intellectual deficits or hearing loss.

Genetic abnormalities are a common cause. Microcephaly can also be triggered by infections of the fetus, including German measles (also known as rubella), toxoplasmosis (a disease caused by a parasite found in undercooked contaminated meat and cat feces) and cytomegalovirus.

Microcephaly may also result if a pregnant woman consumes alcohol, is severely malnourished or has diabetes. If the defect occurs in a child’s first years, it may be a result of a brain injury during labor.

There is no treatment for an unusually small head.

What is microcephaly?

During the first week after onset of symptoms, diagnosed by performing reverse transcriptase-polymerase chain reaction (RT-PCR) on serum.

Virus-specific IgM and neutralizing antibodies typically develop toward the end of the first week of illness; cross-reaction with related flaviviruses (e.g., dengue and yellow fever viruses) is common and may be difficult to discern. Plaque-reduction neutralization testing can be performed to measure virus-specific neutralizing antibodies and discriminate between cross-reacting antibodies in primary flavivirus infections.

Diagnosis

Algorithm for Pregnant Patient

Is there a treatment? -No. The C.D.C. does not recommend a particular antiviral

medication for people infected with the Zika virus.

Treat the symptoms: Get plenty of rest. Drink fluids to prevent dehydration. Take medicine such as acetaminophen to reduce fever and

pain. Do not take aspirin or other non-steroidal anti-inflammatory

drugs.

Treatment

Protection is difficult in mosquito-infested regions. There is no vaccine against the Zika virus. Efforts to make one

have just begun, and creating and testing a vaccine normally takes years and costs hundreds of millions of dollars.

Because it is impossible to completely prevent mosquito bites, the C.D.C. has advised pregnant women to avoid going to regions where Zika is being transmitted, and has advised women thinking of becoming pregnant to consult doctors before going.

Travelers to these countries are advised to avoid or minimize mosquito bites by staying in screened or air-conditioned rooms or sleeping under mosquito nets, wearing insect repellent at all times and wearing long pants, long sleeves, shoes and hats.

Is there a vaccine? How should people protect themselves?

1. Eliminate standing water in and around your home:

Once a week, empty and scrub, turn over, cover, or throw out items that hold water, such as tires, buckets, planters, toys,

pools, birdbaths, flowerpots, or trash containers. Check inside and outside your home.

Tightly cover water storage containers (buckets, cisterns, rain barrels) so that mosquitoes cannot get inside to lay eggs. For containers without lids, use wire mesh with holes smaller than an

adult mosquito.

2. If you have a septic tank, follow these steps:

Repair cracks or gaps. Cover open vent or plumbing pipes. Use wire mesh with holes smaller

than an adult mosquito.

Prevention

3. Keep mosquitoes out of your home

Use screens on windows and doors. Repair holes in screens. Use air conditioning when available.

4. Prevent mosquito bites

Use a repellent with DEET (N, N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023),IR3535 (3-[N-butyl-N-acetyl]-aminopropionic acid) or oil of lemon eucalyptus [p-menthane 3, 8-diol (PMD)] according to the instructions on the product label. When used as directed on the product label, insect repellents containing DEET, picaridin, and IR3535 are safe for pregnant women.

Treat clothing and gear (such as boots, pants, socks, and tents) with permethrin or purchase permethrin-treated clothing and gear.

Wear long-sleeved shirts and long pants

The World Health Organization has declared the Zika virus an international public health emergency, prompted by growing concern that it could cause birth defects. As many as four million people could be infected by the end of the year. Officials at the Centers for Disease Control and Prevention have urged pregnant women against travel to about two dozen countries, mostly in the Caribbean and Latin America, where the outbreak is growing.

The infection appears to be linked to the development of unusually small heads and brain damage in newborns. Some pregnant women who have been to these regions should be tested for the infection, the agency said. Here are some answers and advice about the outbreak.

Recent

No. Outbreaks of Zika previously have been reported in

tropical Africa, Southeast Asia, and the Pacific Islands. Zika virus likely will continue to spread to new areas. In May 2015, the Pan American Health Organization (PAHO) issued an alert regarding the first confirmed Zika virus infection in Brazil.

Are you immune for life once infected? Once a person has been infected, he or she is likely to

be protected from future infections.

Is this a new virus?