Zika virus disease

Zika virus disease is an emerging mosquito borne viral disease. It is transmitted by bite of an infected Aedes mosquito. Zika virus was first identified in Zika forest of Uganda in 1947 in rhesus monkeys. In1952, it was identified in humans, in Uganda and the United Republic of Tanzania through serological tests. The virus was isolated from human samples in Nigeria in 1968. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific.

In 2007, the South Pacific recorded its first outbreak of Zika virus in Yap Island in the Federated States of Micronesia. In October 2013, French Polynesia reported its first outbreak.

In May 2015, the public health authorities of Brazil confirmed the transmission of Zika virus in the northeast of the country. Since October 2015, other countries and territories of the Americas have reported the presence of the virus.

Along with Zika virus infection, cluster of microcephaly (condition where a baby is born with a small head or the head stops growing after birth) cases and other neurological disorders (Guillain-Barré Syndrome) (GBS) reported in Brazil and a similar cluster in French Polynesia in 2014.

World Health Organisation (WHO) strongly suspected a causal relationship between zika virus infection during pregnancy and microcephaly and recommended more investigation and research to understand any possible link. No scientific evidence to date confirms a link between Zika Virus and microcephaly or GBS.

On 1st February 2016, WHO announced that the cluster of neurological disorders and neonatal malformations reported in the Americas region constitutes a Public Health Emergency of International Concern.

Since 2007, Zika viral transmission has been documented in 46 countries and territories including 34 countries which reported autochthonous transmission, or locally acquired infection, between 2015 and 2016, six countries with indication of viral circulation, five countries where the Zika virus outbreak has ended and one country with a locally acquired case but without vector borne transmission(12th February 2016)*.

Find more information on-

Questions and answers about Zika virus-

www.nhp.gov.in/Zika-virus 
who.int/features/qa/zika/en/ 
www.who.int/features/qa/

National Guidelines for Zika virus disease

(a) Guidelines on Zika Virus Disease- http://www.mohfw.nic.in/media/disease-alerts/national-guidelines-zika-virus-disease

(b) Guidelines for integrated vector management for control of Ades mosquito- http://www.mohfw.nic.in/

(c) Do’s And Don’ts- http://www.mohfw.nic.in/

(d) Travel Advisory for Zika Virus Disease- http://www.mohfw.nic.in/

(e) Fact sheet on Zika virus disease (updated on 3 rd February 2016)-  http://www.mohfw.nic.in/

(f) Guidelines on laboratory detection and diagnosis of Zika virus diseasehttp://www.mohfw.nic.in/

Zika virus referral form for laboratory diagnosis(NIV,Pune)niv.co.in/Zika_viral_disease_CRF.pdf

Zika Outbreak: WHO's Global Emergency Response Plan

References-

http://www.wpro.who.int/mediacentre/factsheets/fs

http://www.mohfw.nic.in/

http://www.who.int/mediacentre/factsheets/

http://www.who.int/mediacentre/news/statements/2016/

http://www.who.int/emergencies/zika-virus/situation-report           

http://www.who.int/emergencies/zika-virus/situation-report/  (accessed on 15th February 2016)*

 

A majority of those infected with Zika virus disease either remain asymptomatic (up to 80%) or show symptoms  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.

The incubation period (the time from exposure to symptoms) of Zika virus disease is not clear, but is likely to be a few days.

As compared to Dengue, cases of Zika virus infection has a mild to moderate clinical picture, the onset of fever is more acute and shorter in duration.

Increased cases of Guillain-Barré syndromea (GBS) in general public and microcephalyb in newborns were reported from French Polynesia and Brazil during Zika outbreaks in 2013-2014 and 2015 respectively. Medical experts suspected an association of micocephaly and GBS with Zika virus infection. But no scientific evidence confirms a link so far*.

 (a. Guillain-Barré syndrome-It is a condition in which the body’s immune system attacks part of the nervous system. It can be caused by a number of viruses and can affect people of any age. The main symptoms include muscular weakness and tingling in the arms and legs. Severe complications can occur if the respiratory muscles are affected.)

(b. Microcephaly- It is a condition where a baby is born with a small head or the head stops growing after birth.)

 References-

  www.who.int/csr/disease/zika/en/

  www.who.int/mediacentre/news/statements/2016/

  www.who.int/features/qa/zika/en/

  www.who.int/emergencies/zika-virus/situation-report/who-zika-situation- (accessed on 15th February 2016)*

Zika virus is a mosquito-borne flavivirus closely related to dengue virus.

Transmission-

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

Other species of Ades mosquito Ae. albopictus, Ae. hensilli, Ae. polynesiensis were also found as vector in spread of Zika Virus.

Some evidence suggests Zika virus can also be transmitted to humans through blood transfusion, perinatal transmission and sexual transmission.

Some facts about Ades mosquito-

  • Ae. aegypti is closely associated with human environments and can breed in indoor (flower vases, concrete water tanks in bathrooms), and artificial outdoor (vehicle tyres, water storage vessels, discarded containers) environments.
  • The eggs can survive up to 1 year without water. Once water is available (even small quantities of standing water), the eggs develop into larvae and then adult mosquitoes.
  • Aedes mosquitoes are active during daylight hours, and usually bite during the morning and late afternoon/evening hours.
  • Female Aedes mosquito acquires the virus while feeding on the blood of an infected person.
  • Female Aedes mosquito usually flies an average of 400 metres. But it may be transported accidently by humans from one place to another (e.g. in the back of the car, plants).

References-

www.who.int/csr/disease/zika/en/

www.wpro.who.int/mediacentre/factsheets/

www.who.int/denguecontrol/mosquito/en/

Zika virus infection should be suspected in patients reporting with acute onset of fever, maculo-papular rash and arthralgia, among those individuals who travelled to areas with ongoing transmission during the two weeks preceding the onset of illness.

Zika virus is diagnosed through reverse transcriptase polymerase chain reaction (PCR) and virus isolation from blood samples (for research purpose). Detection of Zika virus by these methods could be done in saliva or urine samples collected during the first 3 to 5 days after symptom onset, or from serum collected in the first 1 to 3 days after onset of disease.

Serological tests, (immunofluorescence assays and enzyme-linked immunosorbent assays) may show the presence of anti-Zika virus IgM and IgG antibodies. Diagnosis by serology is difficult as the virus can cross-react with other flaviviruses such as dengue, West Nile and yellow fever.

In India, National Centre for Disease Control (NCDC), Delhi and National Institute of Virology (NIV), Pune, have the capacity to provide laboratory diagnosis of Zika virus disease in acute febrile stage. These two institutions are the apex laboratories to support the outbreak investigation and for confirmation of laboratory diagnosis. Ten additional laboratories would be strengthened by Indian Council of Medical Research (ICMR) to perform the laboratory diagnosis.

References-

www.who.int/csr/disease/zika/en/

www.mohfw.nic.in/showfile

www.wpro.who.int/mediacentre/factsheets/

There is no specific antiviral treatment for Zika virus. Symptomatic treatment is advised after excluding more severe conditions such as malaria, dengue, and bacterial infection with the consultation of medical personnel. It is important to differentiate Zika virus infection from dengue because of severe complications in some dengue cases. In addition, co-infection with Zika and dengue could occur.

Symptomatic treatment is given in the form of acetaminophen or paracetamol to relieve fever. Antihistaminic drugs may be used to relieve itching due to maculopapular rash.

(The use of aspirin and other non-steroidal anti-inflammatory drugs is not advised, since the cause of the clinical symptoms could be dengue or chikungunya diseases in which the use of non-steroidal anti-inflammatory drugs (NSAIDs) is contraindicated*).  

People sick with Zika virus should get rest, and advised to drink plenty of fluids.

Patient isolation-

The patient is recommended to stay under a bed net (treated or without insecticide), or stay in a place with intact window/door screens. These precautions would prevent patient being bitten by mosquitoes in first week of illness and further spread of infection to others.

In addition, physicians or health care workers who attend to Zika virus-infected patients should protect against mosquito bites by using insect repellent and wearing long sleeves and pants.

Newborns with congenital malformations must be monitored to determine any neuro-developmental outcomes.

There is currently no vaccine available.

References-

www.who.int/csr/disease/zika/en/

 www.wpro.who.int/mediacentre/

 www.paho.org/hq/index.php (accessed on 15th February 2016)*

Potential Complications-
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 (Guillain-Barré syndrome) in general public.
 
WHO experts strongly suspected a causal relationship between Zika virus infection during pregnancy and increased incidence of babies born with microcephaly. However more scientific investigation is required to understand relationship between zika virus and microcephaly.

 
References-

www.who.int

www.who.int

Mosquitoes and their breeding sites pose a significant risk factor for Zika virus infection. Prevention and control depends on reducing mosquitoes through source reduction (removal and modification of breeding sites) and reducing contact between mosquitoes and people.

Directorate General of Health Services (DGHS), Ministry of Health and Family Welfare, Government of India has released National guidelines for prevention of Zika Virus disease. (www.mohfw.nic.in/ )

Prevention and Control of Zika virus disease consist of-

1-Enhanced surveillance-

(i) Community based surveillance-DGHS has recommended for enhanced surveillance at community level by the Integrated Disease Surveillance Programme (IDSP) for detection of primary case and Gullian Barre Syndrome. Maternal and Child Health division is advised to look for clustering of cases of microcephaly among new borns.

(ii)International Airports/ Ports-All the International Airports / Ports authorities are advised to keep watch on passengers returning from affected countries and suffering from febrile illness and to follow the recommended aircraft disinfection guidelines.

(iii)Activation of Rapid Response Teams (RRTs)-RRTs have been advised to be activated at all levels, for investigation of suspected outbreaks. NCDC, Delhi is assigned as nodal agency for investigation of outbreak in any part of the country.

(iv)Laboratory Diagnosis -NCDC, Delhi and NIV, Pune are the apex laboratories to support the outbreak investigation and for confirmation of laboratory diagnosis. ICMR would strengthen ten additional laboratories in the country.

2. Risk communication-The States/ Union territories administrations have to create increased awareness among clinicians including obstetricians, paediatricians and neurologists about Zika virus disease and its possible link with adverse pregnancy outcome (foetal loss, microcephaly). Non-governmental organisation should also be sensitised about Zika virus disease.

3. Vector control- Mosquito control is the only measure that can interrupt the transmission of vector borne viruses such as dengue, chikungunya, and Zika. This can be achieved by enhanced integrated vector management (IVM).

IVM includes-

(a)Vector surveillance- larval surveys and adult surveys, are important for early detection of Ades mosquito population so that proper control measures could be initiated.

(b)Vector management- It includes methods to eliminate mosquito breeding and adult mosquito population. These are –

(i)Environment management methods are used to control immature stages of Ades mosquitoes. Intensify efforts to reduce actual or potential larval habitats in and around houses by:

  • Covering all water containers in the house to prevent fresh egg laying by the vector.
  • Emptying, drying water tanks, containers, coolers, bird baths, pets’ water bowls, plant pots, drip trays at least once each week.
  • Regularly checking for clogged gutters and flat roofs that may have poor drainage.

(ii)Biological control-

  • Introducing larvivorous fishes (e.g., Gambusia / Guppy) in ornamental water tanks/garden.
  • Using endotoxin producing bacteria, Bacillus thuringiensis (Bt H-14) as biological larvicide in stagnant water, poses no danger to humans, non-targeted animal species, or the environment when used according to directions.

(iii)Chemical control-

  • Chemical larvicides are recommended in permanent big water containers where water has to be conserved or stored because of scarcity of water or irregular and unreliable water supply. Temephos (organophate compound) is recommended as a larvicide under public health programme.
  • Adulticide- In areas where autochthonous or imported cases of dengue, chikungunya, and/or Zika virus (as the vector is same) are detected, Pyrethrum spray or Malathion fogging or ultra low volume (ULV) spray are recommended for the control of adult Aedes aegypti mosquitoes.

(c)Personal protective/prevention measures-

  • 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.
  • Since the Aedes mosquitoes are day-biting mosquitoes, it is recommended that those who sleep during the daytime, particularly young children, the sick or elderly, should use insecticide-treated mosquito nets to provide protection.
  • In areas where Zika virus is transmitting patients (infected with dengue, chikungunya, or Zika virus), their household members, and the community, must follow personal preventive measures.

(d)Legislative Measures-

Suitable laws and byelaws should be enacted and implemented for avoidance of situations which favour mosquito breeding at various levels.
 

(e)Health education for community mobilisation and inter-sectoral convergence-

Community participation to eliminate the breeding points of Ades mosquitoes with the involvement of other sectors/departments should be encouraged.

4. Travel advisory-

  • All travellers 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).
  • 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.
  • 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 consult medical expert.

Precautionary measures for pregnant women and women considering pregnancy recommended by WHO-

  • Women who are pregnant should discuss their travel plans with their health care provider and consider delaying travel to any area where locally acquired infection is occurring.
  • Until more is known about the risk of sexual transmission, all men and women returning from an area where zika is circulating especially pregnant women and their parterres should practice safe sex including through the correct and consistent use of condoms.
  • All travellers, including pregnant women, going to an area where locally acquired Zika virus infection is occurring should adhere closely to steps that can prevent mosquito bites during the trip.
    (WHO is not recommending any travel or trade restrictions at this level.)

5. Coordination with international agencies-NCDC, Delhi is a focal point for International Health Regulations (IHR) is authorised to seek/ share information with the affected countries and with World Health Organization for updates on the evolving epidemic.

6. Research- In India, ICMR is advised to conduct research.

Vaccine – Currently there is no vaccine available for prevention of Zika virus disease. According to WHO around 15 pharmaceutical companies have commenced work in this direction. A DNA vaccine from the US National Institutes of Health and an inactivated product from Bharat Biotech in India are at advanced stage. Further vaccines will take at least 18 months for any large-scale trials*.

7. Monitoring-Joint Monitoring group under DGHS is monitoring the situation on regular basis.

Key message-

The best form of prevention is protection against mosquito bites.

References-

www.mohfw.nic.in/showfile.php

nvbdcp.gov.in/dengue12.html

www.who.int/csr/disease/zika/information-for-travelers/

www.who.int/emergencies/zika-virus/situation-report (accessed on 15th February 2016)*

  • PUBLISHED DATE : Feb 16, 2016
  • PUBLISHED BY : Zahid
  • CREATED / VALIDATED BY : Dr. Aruna Rastogi
  • LAST UPDATED ON : May 31, 2017

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