AYESHA FAREED PB II YEAR 07 SVCP.

SEMINAR ON ZIKA VIRUS

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WHO has already declared the Zika virus as a Public Health Emergency of International Concern over its suspected link to microcephaly.

From 2010 to 2014, Brazil only saw an average of 156 cases of microcephaly per year. But from Oct. 2015 to Jan. 2016, Brazil has recorded over 4,000 reported cases, though they have been able to investigate and discard 462 initial diagnoses according to an update last month. 

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INTRODUCTION

Zika virus is an emerging mosquito-borne virus that was first identified in Uganda in 1947 in rhesus monkeys through a monitoring network of sylvatic yellow fever. It was subsequently identified in humans in 1952 in Uganda and the United Republic of Tanzania. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific.

Genre: Flavivirus Vector: Aedes mosquitoes (which usually bite during

the morning and late afternoon/evening hours) Reservoir: Unknown

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SIGNS AND SYMPTOMS The incubation period (the time from exposure to

symptoms) of Zika virus disease is not clear, but is likely to be a few days. The symptoms are similar to other arbovirus infections such as dengue, and include fever, skin rashes, conjunctivitis, muscle and joint pain, malaise, and headache. These symptoms are usually mild and last for 2-7 days.

During large outbreaks in French Polynesia and Brazil in 2013 and 2015 respectively, national health authorities reported potential neurological and auto-immune complications of Zika virus disease. Recently in Brazil, local health authorities have observed an increase in Zika virus infections in the general public as well as an increase in babies born with microcephaly in northeast Brazil. Agencies investigating the Zika outbreaks are finding an increasing body of evidence about the link between Zika virus and microcephaly. However, more investigation is needed before we understand the relationship between microcephaly in babies and the Zika virus. Other potential causes are also being investigated.

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TRANSMISSION

Zika virus is transmitted to people through the bite of an infected mosquito from the Aedes genus, mainly Aedes aegypti in tropical regions. This is the same mosquito that transmits dengue, chikungunya and yellow fever.

Zika virus disease outbreaks were reported for the first time from the Pacific in 2007 and 2013 (Yap and French Polynesia, respectively), and in 2015 from the Americas (Brazil and Colombia) and Africa (Cape Verde). In addition, more than 13 countries in the Americas have reported sporadic Zika virus infections indicating rapid geographic expansion of Zika virus.

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DIAGNOSIS

Zika virus is diagnosed through PCR (polymerase chain reaction) and virus isolation from blood samples. Diagnosis by serology can be difficult as the virus can cross-react with other flaviviruses such as dengue, West Nile and yellow fever.

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PREVENTION Mosquitoes and their breeding sites pose a significant

risk factor for Zika virus infection. Prevention and control relies on reducing mosquitoes through source reduction (removal and modification of breeding sites) and reducing contact between mosquitoes and people.

This can be done by using insect repellent; wearing clothes (preferably light-coloured) that cover as much of the body as possible; using physical barriers such as screens, closed doors and windows; and sleeping under mosquito nets. It is also important to empty, clean or cover containers that can hold water such as buckets, flower pots or tyres, so that places where mosquitoes can breed are removed.

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• Special attention and help should be given to those who may not be able to protect themselves adequately, such as young children, the sick or elderly.

• During outbreaks, health authorities may advise that spraying of insecticides be carried out. Insecticides recommended by the WHO Pesticide Evaluation Scheme may also be used as larvicides to treat relatively large water containers.

• Travellers should take the basic precautions described above to protect themselves from mosquito bites.

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TREATMENT

Zika virus disease is usually relatively mild and requires no specific treatment. People sick with Zika virus should get plenty of rest, drink enough fluids, and treat pain and fever with common medicines. If symptoms worsen, they should seek medical care and advice. There is currently no vaccine available.

Do not take aspirin and other non-steroidal anti-inflammatory drugs.

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ZIKA VIRUS IN PREGNANCY Zika virus can be spread from a pregnant

woman to her unborn baby. There have been reports of a serious birth defect of the brain called microcephaly and other poor pregnancy outcomes in babies of mothers who were infected with Zika virus while pregnant. Knowledge of the link between Zika and these outcomes is evolving, but until more is known, CDC recommends special precautions for the following groups:

Women who are pregnant (in any trimester):• Consider postponing travel to any area where Zika virus transmission is ongoing.• If you must travel to one of these areas, talk to your doctor first and strictly follow steps to prevent mosquito bites during your trip.

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Women who are trying to become pregnant:• Before you travel, talk to your doctor about your plans to become pregnant and the risk of Zika virus infection.• Strictly follow steps to prevent mosquito bitesduring your trip.Specific areas where Zika virus transmission is ongoing are often difficult to determine and are likely to change over time. As more information becomes available, this travel notice will be updated. Please check back frequently for the most up-to-date recommendations. 

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What can travelers do to prevent Zika?There is currently no vaccine to prevent or medicine to treat Zika. Travelers can protect themselves by preventing mosquito bites:• Cover exposed skin by wearing long-sleeved shirts and long pants.• Use EPA-registered insect repellents containing DEET, picaridin, oil of lemon eucalyptus (OLE), or IR3535. Always use as directed.• Pregnant and breastfeeding women can use all EPA-registered insect repellents, including DEET, according to the product label.• Most repellents, including DEET, can be used on children aged > 2 months.• Use permethrin-treated clothing and gear (such as boots, pants, socks, and tents). You can buy pre-treated clothing and gear or treat them yourself.• Stay and sleep in screened-in or air-conditioned rooms.

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WHO RESPONSE WHO is supporting countries to control Zika

virus disease through: Define and prioritize research into Zika virus

disease by convening experts and partners. Enhance surveillance of Zika virus and

potential complications. Strengthen capacity in risk communication to

help countries meet their commitments under the International Health Regulations.

Provide training on clinical management, diagnosis and vector control including through a number of WHO Collaborating Centres.

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• Strengthen the capacity of laboratories to detect the virus.

• Support health authorities to implement vector control strategies aimed at reducing Aedes mosquito populations such as providing larvicide to treat standing water sites that cannot be treated in other ways, such as cleaning, emptying, and covering them.

• Prepare recommendations for clinical care and follow-up of people with Zika virus, in collaboration with experts and other health agencies.

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VACCINE DEVELOPMENT

Work has begun towards developing a vaccine for Zika virus, according to Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. The researchers at the Vaccine Research Center have extensive experience from working with vaccines for other viruses such as West Nile virus, chikungunya virus, and dengue fever. Nikos Vasilakis of the Center for Biodefense and Emerging Infectious Diseases predicted that it may take two years to develop a vaccine, but 10 to 12 years may be needed before an effective Zika virus vaccine is approved by regulators for public use.

Bharat Biotech, a Hyderabad based Indian drug company has claimed that they have developed a vaccine for Zika virus, but they are in the process for approval to be released officially.

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• There is now a rush to develop a vaccine. Global firms includingFrance’s Sanofi and Japan’s Takeda have begun their own research. But Bharat Biotech was the first company to file a patent for a Zika vaccine, which is now in pre-clinical testing as the firm prepares to test it on animals.

• It is not clear if and when Bharat’s vaccines will reach the market. Animal testing is expected to take about five months, and then they would need to be tested on humans. The vaccine doesn’t just need to be effective in trials; Indian regulatory authorities also need to expedite the process, Ella said. Passing through those stages could take many years, but Ella is confident that, once approved, Bharat Biotech can produce millions of doses within months.

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CDC GUIDELINES The US Centers for Disease Control and Prevention

(CDC) has issued interim guidelines for the evaluation, testing, and management of infants with possible congenital Zika virus infection. The guidelines recommend Zika virus testing for infants with microcephaly or intracranial calcifications who were born to women who traveled to or resided in an area with Zika virus transmission while pregnant and for infants born to mothers with positive or inconclusive test results for Zika virus infection. In these situations, the CDC recommends:

Testing infant serum for Zika virus RNA, Zika virus immunoglobulin M (IgM) and neutralizing antibodies, and dengue virus IgM and neutralizing antibodies. The initial sample should be collected either from the umbilical cord or directly from the infant within 2 days of birth, if possible.

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• If cerebrospinal fluid is obtained for other studies, it should also be tested for Zika virus RNA, Zika virus IgM and neutralizing antibodies, and dengue virus IgM and neutralizing antibodies.

• Histopathologic evaluation of the placenta and umbilical cord with Zika virus immunohistochemical staining on fixed tissue and Zika virus reverse transcription-polymerase chain reaction on fixed and frozen tissue may also be considered.

• If not already performed during pregnancy, test mother's serum for Zika virus IgM and neutralizing antibodies and dengue virus IgM and neutralizing antibodies.

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MICROCEPHALY

Microcephaly is a neurodevelopment disorder where an infant’s head does not develop normally and remains abnormally small when compared to the heads of others the same age and sex.

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• Microcephaly means “small head.” It is very similar to and should not be confused with the word microencephaly, which means “small brain.” The skull size (and thus head size) is determined by brain size, therefore a person with microcephaly is guaranteed to have microencephaly as well.

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HISTORY Microcephaly was first noticed in

children of pregnant Japanese women who survived the atomic bombings of Hiroshima and Nagasaki. The radiation mutated the children.

Currently there is a heavy presence of microcephalic children in Amish country in Philadelphia

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CAUSES Microcephaly is the result of a mutation

on one of the six microcephalin genes. The most common being the MCPH1gene.

Each gene corresponds to one of the three common types of microcephaly: Autosomal Dominant Autosomal Recessive (most common) X-Linked

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CAUSES There are two forms of microcephaly. They

are determined by when the mutation occurs. If it is in the womb it is congenital onset microcephaly. If it occurs after birth it is postnatal onset microcephaly.

Microcephaly can either be inherited from parents that carry the mutated gene or can occur randomly due to a plethora of disorders and environmental conditions.

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SYMPTOMS Microcephaly results in an abnormally small head size.

With this comes multiple symptoms: Dwarfism Delayed motor and speech functions Mental retardation Facial distortions Seizures Hyperactivity Balance and coordination problems Shortened life span Limited mental capacity

Some people with microcephaly have grow up to have normal intelligence.

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CURE There is no cure for microcephaly. It is impossible

without the technology to stimulate nerve cell growth, which has yet to be developed.

Current treatment focuses on mitigating the effects of the symptoms of microcephaly. If caught early on, speech therapy and physical

therapy may be able to mitigate the effects of motor and speech dysfunction that is sure to ensue.

Medicine to treat hyperactivity has been developed. Scientists have recently discovered that amino acid

therapy can significantly reduce the occurrence of seizures.

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PROGNOSIS FOR MICROCEPHALY Prognosis for microcephaly varies and

depends on the presence of other existing medical conditions.

In general, life expectancy for children with microcephaly is reduced and the chances for attaining normal brain function is reduced.

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KEY FACTS

Zika virus disease is caused by a virus transmitted by Aedes mosquitoes.

People with Zika virus disease usually have a mild fever, skin rash (exanthema) and conjunctivitis. These symptoms normally last for 2-7 days.

There is no specific treatment or vaccine currently available.

The best form of prevention is protection against mosquito bites.

The virus is known to circulate in Africa, the Americas, Asia and the Pacific.

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REFERENCES Sternberg, Steve (22 January 2016). 

"Vaccine Efforts Underway as Zika Virus Spreads". US News & World Report. Retrieved 28 January 2016.

James Cook (27 January 2016). "Zika virus: US scientists say vaccine '10 years away'—BBC News". BBC News. Retrieved 28 January 2016.

 "Zika Travel Health Notices". www.cdc.gov. CDC. Retrieved24 January 2016.

 "Microcephaly in Brazil potentially linked to the Zika virus epidemic, ECDC assesses the risk". European Centre for Disease Prevention and Control. Retrieved 18 January 2016.

CDC Issues Interim Guidance on Congenital Zika Virus Infection- CDC.

WHO fact sheet. Expert comment on Zika virus outbreak in the Americas-

London school of hygiene and tropical medicine. Lara C. Pullen, PhD; Zika Virus Spreading in Latin America,

Raising Concerns Medscape News.

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