Thursday, 4 February 2016


Zika Virus Update

DR K K Aggarwal

Is Zika virus infection a public health emergency?

On 1st February, 2016, the WHO declared the mosquito-borne Zika virus an international public health emergency due to its link to thousands of birth defects in Brazil. This coordinated international action was needed to improve detection and expedite work on a vaccine and better diagnostics for the disease; however, there are no curbs on travel or trade.

What is a public health emergency of international concern?

Formally, a PHEIC — pronounced "fake" — is defined as "an extraordinary event which is determined to constitute a public health risk to other States through the international spread of disease and to potentially require a coordinated international response." It’s a political tool used by the WHO to sound the alarm about a serious disease that has caught the world off guard and put people's health in danger. It is meant to draw countries' immediate attention to galvanize resources and stop the disease from spreading further across borders.

Who decides to declare a public health emergency?

The WHO convenes a panel of experts under the International Health Regulations (which are a set of laws that govern global responses to pandemics involving 196 member countries). These experts — dubbed an "emergency committee" meet and assess the risk posed by a disease outbreak and then advise the WHO Director General about whether to declare a PHEIC, who then decides whether to take action.

How often does the WHO declare these emergencies?

Not very often. The WHO has only declared a public health emergency three times since the International Health Regulations were enacted in 2007. The first time was in 2009, with the outbreak of the H1N1 swine flu pandemic. The second time was in May 2014, when polio seemed to surge again, threatening the eradication effort. The third time, in August 2014, came as the Ebola outbreak in West Africa was growing out of control. Notably, the emergency committee decided not to declare the MERS virus a PHEIC.

Zika declaration is the fourth PHEIC in history. It is also the first time the WHO has issued such a warning over a mosquito-borne disease.

Why are these declarations so rare?

PHEIC is a political tool used to focus the world's attention on a health crisis. Using this declaration too often would weaken its significance. One of the key considerations in declaring a PHEIC is whether the disease threat is dire enough for countries to be forced into enacting travel and trade restrictions. These can be devastating to local economies.

Even if the WHO only warns people to limit or delay travel to affected regions (instead of outright travel restrictions), health emergency declarations are often associated with economic losses.

Because of the Ebola crisis, the World Bank Group estimated that the West African countries at the center of the outbreak — Guinea, Liberia, and Sierra Leone — lost out on about $1.6 billion in economic growth in 2015. Similarly, the South American countries hit by swine flu suffered economic losses ranging from 0.5 to 1.5 percent of their GDPs.

Zika does not even cause symptoms in most people. So why did the WHO declare a PHEIC?

It is really Zika's link with microcephaly that prompted the PHEIC. So, it's not the Zika virus itself that prompted the PHEIC, per se, but it's the virus' potential to harm newborns, even though this link is not yet fully established or understood.

Do these declarations have any impact beyond economic repercussions?

Naming a PHEIC does not mean the countries battling an outbreak will suddenly be flooded with funds and support from the WHO. In Ebola, the three worst-affected countries also happened to be some of the poorest on the planet. The emergency declaration escalated media attention and global focus on the disease. It helped wake up the world to the gravity of West Africa's outbreak. It helped bring resources from wealthier countries into West Africa, and slowly the global effort got the outbreak under control.

What will this health emergency mean for Latin America?

The WHO is not recommending any restrictions on travel and trade. This puts them at odds with the CDC, which advised pregnant women to avoid travel to Zika-infected countries.

For now, the WHO is alerting countries to the threat of Zika and advising health officials to coordinate a public health response. This involves taking measures to strengthen surveillance of Zika cases and associated birth and neurological complications, controlling mosquito populations that carry the virus, and expediting the development of a vaccine as well as improved diagnostic tests for the virus. A PHEIC also means the WHO will closely track and monitor the disease and issue regular media updates about the outbreak. It'll draw global attention to the disease, and probably encourage governments and health agencies in and out of Latin America to research Zika and send resources to places that need them in order to help stop the virus from traveling further

What are the guidelines from Ministry of Health & Family Welfare, Govt. of India regarding Zika virus infection?

The Ministry of Health has advised an Integrated Disease Surveillance Programme (IDSP) through its community and hospital-based data gathering mechanism to track clustering of acute febrile illness and seek primary case, if any, among those who travelled to areas with ongoing transmission in the 2 weeks preceding the onset of illness. The IDSP would also advise its State and District level units to look for clustering of cases of microcephaly among newborns and reporting of Gullian Barre Syndrome. The Maternal and Child Health Division (under NHM) would also advise its field units to look for clustering of cases of microcephaly among newborns

What is CDC advisory regarding travel?

CDC recently advised pregnant women to avoid traveling to parts of the Caribbean and Central and South America where Zika virus transmission is ongoing in a Level 2 travel alert ‘Follow enhanced precautions for this destination’. But, the government did not ban them from traveling there.

What is Ministry of Health, Govt. of India advisory regarding travel?

·         Non-essential travel to the affected countries to be deferred/ cancelled.
·         Pregnant women or women who are trying to become pregnant should defer/ cancel their travel to the affected areas.
·         All travelers to the affected countries/ areas should strictly follow individual protective measures, especially during day time, to prevent mosquito bites (use of mosquito repellent cream, electronic mosquito repellents, use of bed nets and dress that appropriately covers most of the body parts).
·         Persons with comorbid conditions such as diabetes, hypertension, chronic respiratory illness, Immune disorders etc. should seek advice from the nearest health facility, prior to travel to an affected country.
·         Travellers having febrile illness within two weeks of return from an affected country should report to the nearest health facility.
·         Pregnant women who have travelled to areas with Zika virus transmission should mention about their travel during antenatal visits in order to be assessed and monitored appropriately.

What is the IMA advisory?

The IMA advises that pregnant women (0-12 weeks) visiting Zika affected countries at the time of visa application should ask for travel advisory with regard of Zika virus of that country and follow that.

Will Zika virus enter India and if yes, how will it behave?

It is not necessary. The Aedes mosquito is common in India but behaves differently here. Yellow fever is transmitted by the Aedes mosquito, yet yellow fever virus has never entered India. Dengue virus has entered and has spread like an epidemic; Chikungunya virus too has entered but has remained sporadic. So Indians should not panic until cases are reported.

Which are the affected countries?

The 24 countries and territories at risk are: Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique,     Mexico, Panama, Paraguay, Suriname, Venezuela, Commonwealth of Puerto Rico,   Barbados, Bolivia, Ecuador, Guadeloupe, Saint Martin, Guyana, Cape Verde, Samoa, U.S. Virgin Islands and Dominican Republic

What is Zika virus?

Zika virus is a member of the Flaviviridae virus family and the Flavivirus genus, transmitted by daytime-active Aedes mosquitoes, such as A. aegypti. The virus is related to dengue, yellow fever, Japanese encephalitis and West Nile viruses.

What is Zika virus infection?

Zika virus infection is similar to a mild form of dengue fever and is generally a mild illness in adults. Only one in five individuals who catch the virus develops symptoms, which usually disappear within a week. It is treated by rest and cannot yet be prevented by drugs or vaccines.

There is a possible link between Zika fever and microcephaly in newborn babies by mother-to-child transmission, and with neurologic conditions in infected adults, including cases of the Guillain–Barré syndrome. Newborn babies of mothers who had a Zika virus infection during the first trimester of pregnancy are at an increased risk of microcephaly.  The fetus is apparent at highest risk when the mother acquires the infection during the 1st trimester.

Is the link with microcephaly confirmed?

As per WHO, it is "strongly suspected but not yet scientifically proven" that Zika causes microcephaly.

Is the aedes mosquito present in all parts of the world?

Aedes mosquitoes populate the entire region except for Canada and continental Chile.

What is microcephaly?

The abnormally small heads of these babies often are accompanied by incomplete brain development, which can lead to a lifetime of health problems. In severe cases, newborns do not survive for long.

What is the advisory for Colombia and El Salvador?

These countries have urged women to delay becoming pregnant and in the case of El Salvador, until 2018.

Should the disease be tracked at the airports?

With at least 80% of those infected showing no symptoms, tracking the disease is extremely difficult.

What is the Ministry of Health advisory for International Airports/ Ports?

·         All the International Airports / Ports will display billboards/ signage providing information to travelers on Zika virus disease and to report to Custom authorities if they are returning from affected countries and suffering from febrile illness.
·         The Airport / Port Health Organization (APHO / PHO) would have quarantine / isolation facility in identified Airports.
·         Directorate General of Civil Aviation, Ministry of Civil Aviation  will be asked to instruct all international airlines to follow the recommended aircraft disinfection guidelines
·         The APHOs shall circulate guidelines for aircraft disinfection (as per International Health Regulations) to all the international airlines and monitor appropriate vector control measures with the assistance from NVBDCP in airport premises and in the defined perimeter.

Will Zika spread in Britain?

Britain is unlikely to be affected because Aedes aegypti cannot survive the cold of UK winters. But, couples returning from south or central America have been warned not to try for a baby for at least a month in case they have become infected.

What are the diagnostic criteria for Zika virus infection?

The diagnosis of Zika virus infection should be suspected in individuals with relevant epidemiologic exposure (travel to an area where the Aedes mosquito is present and where imported or local cases have been reported, within two weeks prior to onset of illness) and characteristic clinical symptoms (2 or more of the following):

·         Low-grade fever (37.8 to 38.5°C)
·         Maculopapular rash
·         Arthralgia (notably the small joints of hands and feet)
·         Conjunctivitis (nonpurulent)

How is the diagnosis of Zika virus infection confirmed?

The diagnosis of Zika virus infection is confirmed by reverse-transcription polymerase chain reaction (RT-PCR) for viral RNA or serology.

·         0-7 days: After onset of symptoms, do a RT-PCR of serum for detection of Zika virus RNA. Negative results cannot exclude infection because the test is positive only for a brief window (3 to 7 days) when the infected person has viremia. RT-PCR assay should also be done for dengue and chikungunya viruses.

·         After 4 days of symptom onset: Test for Zika virus IgM and neutralizing antibody titers that are ≥4-fold higher than dengue virus neutralizing antibody titers in serum. If the Zika virus neutralizing antibody titers are <4-fold higher than dengue virus neutralizing antibody titers, then the test is considered inconclusive. Virus-specific neutralizing antibodies may help to differentiate between cross-reacting antibodies from other flavivirus infections.

Acute and convalescent sera should be obtained to detect an increased antibody titer in paired samples with an interval of 2 to 3 weeks. Serology for both dengue and chikungunya virus infection should also be done. All serologic results should be interpreted with caution since there can be cross-reactivity with other flaviviruses (including dengue virus and West Nile virus).

  • Patients presenting 4 to 7 days after symptom onset: Both RT-PCR and serology may be performed.
  • Serology should be done for asymptomatic pregnant women with Zika virus exposure and positive ultrasound findings.
What are the ultrasound criteria for diagnosis of Zika virus infection?

The ultrasound criteria for diagnosis of Zika virus infection include the presence of microcephaly or intracranial calcifications.

How is microcephaly diagnosed?

·         Microcephaly, for the purpose of evaluating an infant for possible congenital Zika virus infection, is defined as occipitofrontal circumference less than the third percentile, based on standard growth charts for sex, age and gestational age at birth.
·         The occipitofrontal circumference should be disproportionately small as compared to the length of the infant and which is not explained by other etiologies or congenital disorders in order to establish a diagnosis of microcephaly. 
·         If the occipitofrontal circumference of an infant is ≥ the third percentile but is notably disproportionate to the length of the infant, or if the infant has deficits related to the central nervous system, additional evaluation for Zika virus infection may also be appropriate.
·         An infant with microcephaly or intracranial calcifications born to a mother who has been potentially infected with Zika virus during pregnancy should be tested for Zika virus infection
·         The infant should also undergo an ophthalmologic evaluation (including retina examination) and a hearing evaluation in the first month of life
·         Microcephaly is usually not easy to diagnose before the 3rd trimester. 
·         Sometimes, calcifications may be evident in the 2nd trimester but they are more often evident in the 3rd trimester. Ultrasound findings associated with Zika virus infection so far have been observed at 29 to 30 weeks gestation.

Will the Zika virus outbreak in Brazil affect the Olympic Games?

Brazil is due to host the Olympics in Rio de Janeiro in August this year. But,

  • There is no risk of cancelling the games due to Zika.
  • There is zero risk if you are not a pregnant women
  • Pregnant women "can consider" delaying travel but if they needed to travel they should take protective measures by covering up and using mosquito repellent.
  • This is not an Ebola-type situation where you have to stop people at the border.

Is Zika virus associated with Guillain-Barré syndrome?

It is not know conclusively if Zika virus infection causes Guillain-Barre syndrome. But, an association between the two has been observed.

Which is the first step suggested by the testing algorithm provided by the CDC for pregnant women with history of travel to an area with Zika virus who are asymptomatic 2 weeks after travel?

RT PCR testing

Is amniocentesis recommended in women with suspected Zika virus infection?

While amniocentesis is a relatively safe test, the associated risk and benefits should always be considered. A positive RT-PCR result on amniotic fluid would be suggestive of intrauterine infection, which can help physicians to draw up a strategy for management of the patient. However, early amniocentesis (≤ 14 weeks of gestation) is not recommended.

What is the treatment of pregnant women with laboratory evidence of Zika virus?

Treatment is supportive and includes rest, fluids, and analgesics and antipyretics. There is no specific antiviral treatment.

Can Zika virus be transmitted through sexual route?

Yes. Though the CDC has made no recommendation regarding the possible sexual transmission of the virus, a statement issued by the CDC said that the best way to avoid Zika virus infection was "to prevent mosquito bites and to avoid exposure to semen from someone who has been exposed to Zika virus or has been ill from Zika virus infection ". How long? For a few weeks.

Zika can be transmitted through blood, but this is an infrequent mechanism. The usual recommendations for safe transfusions should be followed (e.g., healthy volunteer donors).  

What is the difference between Zika, dengue and chikungunya?

All these diseases present similar symptoms, but certain symptoms suggest one disease or another: 

  • Dengue usually presents with higher grade of fever and more severe muscle pain. There can be complications when the fever breaks; attention should be paid to warning signs such as bleeding. 
  • Chikungunya presents with higher fever and more intense joint pain, affecting the hands, feet, knees, and back. It can disable people, bending them over so that they cannot walk or perform simple actions such as opening a water bottle. 
  • Zika does not have clearly characteristic features, but most patients have skin rashes and some have conjunctivitis.

What measures should be taken to prevent Zika virus infection? 

Prevention involves reducing mosquito populations and avoiding bites, which occur mainly during the day. Eliminating and controlling A. aegypti mosquito breeding sites reduces the chances that Zika, chikungunya and dengue will be transmitted. An integrated response is required, involving action in several areas, including health, education and the environment. 

Recommendations to eliminate and control the mosquito 

  • Do not allow standing water in outdoor containers (flower pots, bottles and containers that collect water) so that they do not become mosquito breeding sites. 
  • Cover domestic water tanks so that mosquitoes cannot get in. 
  • Avoid accumulating garbage; put it in closed plastic bags and keep it in closed containers. 
  • Unblock drains that could accumulate standing water. 
  • Use screens and mosquito nets in windows and doors to reduce contact between mosquitoes and people. 

Recommendations to prevent mosquito bites,

People who live in areas where there are cases of the disease, as well as travellers and, especially, pregnant women should:  

  • Cover exposed skin with long-sleeved shirts, trousers and hats
  • Use repellents recommended by the health authorities (and apply them as indicated on the label)
  • Sleep under mosquito nets. 

People with symptoms of Zika, dengue, or chikungunya should visit a health center

1 comment:

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