1. فيروس زيكا Zika Virus Prof. Dr. Abdelraouf A. Elmanama
Medical Laboratory Sciences Department
Islamic University-Gaza

2. zika virus Prof. Dr. Abdelraouf A. Elmanama
Prof. Dr. Abdelraouf A. Elmanama
Medical Laboratory Sciences Department
Islamic University-Gaza

3. outline Introduction Classification of zika virus
Structure of zika virus
Epidemiology
Transmission
The cycle of the disease
Diagnosis
Treatment
Prevention and control

4. Zika Virus An arthropod-borne virus (arbovirus).
A member of the Flavivirus genus in the family Flaviviridae.
It is related to other pathogenic vector borne flaviviruses including
Dengue,
Yellow fever
West Nile
Japanese encephalitis viruses.

5. Name origin
It owes its name from Zika Forest of Uganda, where it was first isolated in 1947.
The infection, known as Zika Fever.
In humans it was first identified in 1952 in Uganda and United Republic of Tanzania and the virus was first isolated in Nigeria in 1968.
The sporadic cases of infection were reported in Southeast Asia and Sub-Saharan Africa.

6. Systematic Classification of Zika Virus
Group IV ((+)ssRNA)
Group
Flaviviridae
Family
Flavivirus
Genus
Zika virus
Species

7. Structure of Zika Virus
Zika virions are typically icosahedral-shaped.
They are enveloped.
18-45 nanometer in diameter.

8. The genome is a positive strand RNA enclosed in a capsid and surrounded by a membrane.
The RNA contains 10,794 nucleotides encoding 3,419 amino acids.
The virus is inactivated by ether, sodium dexoxycholate and chloroform.

9. Zika virus genome structure

10. Epidemiology
Zika virus was first isolated in 1947 from the blood of a Rhesus monkey in Zika forest, in Uganda
Subsequently, the virus was recovered from humans and mosquitoes in Uganda, Senegal, Nigeria, Ivory Coast, the Central African Republic and Malaysia.
An outbreak of Zika virus was reported in 2007 on Yap Island of Micronesia
Another outbreak in the Pacific was reported in French Polynesia in 2013 and later spread to New Caledonia
In 2015, Zika virus emerged in South America with further spread across the Americas.

11. Epidemiology (CONT.,)
WHO estimates 3 million to 4 million people across the Americas will be infected with the virus in the next year.

12. Recent outbreak
ZIKA virus moved out of Asia and Africa and caused an epidemic in YAP islands of Micronesia (2007) and French Polynesia, New Caledonia, The Cook Islands and in Easter Islands in 2013 and 2014.
In 2015 there has been an upsurge in ZIKA infection dramatically in America with Brazil being most affected; 444,000 to 1.3 million cases reported through December 2015.
It has been reported that ZIKA infection has spread to 23 countries across America.

14. Reproductive Cycle of a Zika virus
The reproductive cycle of ZIKV follows that of other known flaviviruses.
The reproductive cycle of ZIKV follows that of other known flaviviruses.
First, the virion attaches to the host cell membrane receptors via the envelope protein which induces virion endocytosis.
Next, the virus membrane fuses with the endosomal membrane and the ssRNA genome of the virus is released into the cytoplasm of the host cell.
It is then translated into a polyprotein that is subsequently cleaved to form all structural and non-structural proteins. Replication then takes place at intracellular compartments known as cytoplasmic viral factories in the endoplasmic reticulum resulting in a dsRNA genome. The dsRNA genome is then transcribed resulting in additional ssRNA genomes. Assembly then occurs within the endoplasmic reiticulum and the new virions are transported to the Golgi apparatus and then excreted into the intracellular space where the new virions can infect new host cells

15. Transmission Zika Virus spreads to people through mosquito bites .
It was first recovered from mosquitoes of Aedes genus including:
Aedes aegypti
Aedes africanus
Aedes apicoargenteus
Aedes leuteocephalus
Aedes vitattus
Aedes furcifer
Some evidence suggests that Zika Virus can also be transmitted to humans through
Blood transfusion,
Perinatal transmission and
Sexual transmission.

16. Aedes albopictus
Aedes albopictus was identified as the primary vector for ZIKA transmission during 2007 Gabon outbreak

17. The Disease cycle 2-5 days viremia in host 5-7 days in mosquito
Reservoir
host
Mosquito
Resorvoir host
2-5 days viremia in host
5-7 days in mosquito
Then back to the host.

18. Pathogenesis
Mosquito-borne flaviviruses are thought to replicate initially in dendritic cells near the site of inoculation.
Then spread to lymph nodes and the bloodstream.
Although flaviviral replication is thought to occur in cellular cytoplasm, one study suggested that Zika Virus antigens could be found in infected cell nuclei.

19. Incubation period
The incubation period of Zika virus disease is not clear, but is likely to be 3-12 days.

20. Signs and symptoms
only 20-25% of people infected with Zika virus develop symptoms. The most common symptoms of this infection are:
Headache
Fever
Skin rashes (exanthema)
Pink eye
Conjunctivitis
Muscle and joint pain
Malaise

21. Diagnosis of zika virus
Polymersase Chain Reaction :Nucleic acid detection by reverse transcriptase-polymerase chain reaction (RT-PCR).
Nucleic Acid Amplification Test :Nucleic acid amplification test (NAT) for detection of viral RNA can also be performed.
Plaque Reduction Neutralization Assay The Plaque reduction neutralization assay generally has improved specificity over immunoassays, but may still yield cross-reactive results in secondary flavivirus infections.

22. Diagnosis of zika virus (cont.,)
Serological Tests :
An ELISA has been developed to detect IgM to ZIKV only after five days.
NS1 antigen can be detected by ELISA in acute phase specimens
Important Note !!!!!!
IgM antibodies against Zika virus, dengue viruses, and other flaviviruses have strong cross-reactivity which may generate false positive results in serological tests.

23. treatment
No specific vaccine or medications are available to prevent or treat ZIKA virus infections

24. Prevention and control of zika virus
Avoid travel to areas with an active infestation.
Reducing mosquito populations through source reduction (removal and modification of breeding sites)
 Reducing contact between mosquitoes and people through:
wearing clothes (preferably light-coloured) that cover as much of the body as possible
using physical barriers such as window screens
closed doors and windows
sleeping under mosquito nets 
Using repellents 

25. World Health Organization has declared the Zika outbreak a global health emergency

26. Recommendations
A research to determine the types of mosquitoes in Gaza strip is urgently needed Mosquitoes control program should have been started from February. Biological control through the use of BT bacteria has proved effective in reducing the number of mosquitoes. Awareness campaign should be launched

27. THANK YOU