Zika - Epidemiology and control

1. 09-12-2021 1

2. ZIKA VIRUS
EPIDEMIOLOGY AND CONTROL
09-12-2021 2
Dr Lakshmi Rajeev
Assistant Professor
Department Of Community Medicine

3. Introduction
•Mosquito borne Flavivirus
•First identified from Uganda in 1947
•Till 1952- disease specific to monkeys
•First in humans- Uganda and United Republic of Tanzania,1952
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4. Introduction (continued)
•Largest outbreak – 2015 -201633 countries
•Worst – Brazil -1.4 million cases
•WHO- Public Health Emergency of International
Concern (PHEIC) -1stFeb 2016
•86 countries/territories –till date
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5. Problem statement – India
•2016 – First 3 cases reported from Gujarat- routine surveillance
•Sep-Oct 2018- Biggest outbreak(157 cases)- Rajasthan
•Other states- Madhya Pradesh, Maharashtra, Uttar Pradesh
•2021- Kerala
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6. Problem Statement - Kerala
24 year old pregnant ,third trimester- Parassala,
Thiruvanathapuram
Fever ,headache and generalized rash -28/06/2021
ZIKV confirmed (RT-PCR)-08/07/21
13 hospital staffs/patients positive -10/07/21
Active and passive surveillance – 70 positives/590 samples
All resided/travelled to Thiruvanathapuram
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7. Agent
•Zika Virus
•Arbovirus- Flavivirus genus
•Single stranded RNA virus
•One serotype
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8. Vector
•Aedes aegypti (most common) A.albopictus
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9. Aedes aegypti
Day time biter
Highest bite rate- dawn and dusk
Highly domestic
Nervous feeder
Flight range -100m(short fliers)
Multiple cases & clustering of cases
Breeds- artificial water collections
Same vector responsible for ?
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10. Host factors
•Lack of herd immunity
•Pregnancy- Complications
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11. •Rain fall and humidity
•Frequency of bites increases with temperature
•Wide geographical distribution of vector
•High vector density
•International travel
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Environmental factors

12. Modes of transmission
•Bite of Aedes mosquito- most common
•Human to human
-Pregnant mother to foetus- intra uterine and perinatal
-Sexual contact
-Blood transfusion
-Organ transplantation
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13. Clinical features
•Incubation period- 3 to 14 days
•Only 1 in 4 infected people develop symptoms
•Symptoms- Fever, maculo-papular rash, conjunctivitis, muscle and
joint pain, malaise, headache
•Lasts for 2 to 7 days
•Viremia –3rd and 5th day of onset
•Severe forms of disease and fatalities are rare
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14. 1. Pregnancy related– trans placental transmission
symptomatic/asymptomatic mothers
•Congenital Zika Syndrome
-Microcephaly
-Limb contractures
-Eye abnormalities
-Hearing loss
•Abortion/Still birth
•Preterm birth
Complications
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15. Complications (continued)
2. Neurological complications(rare)- older children and adults
• Guillain-Barre Syndrome(GBS)
• Neuropathy
• Myelitis
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16. Zika virus disease- Case definitions
•Suspected Zika virus disease
Acute onset of fever, maculo-papular rash, arthralgia in
those with history of travel to areas with ongoing
transmission during 2 weeks preceding onset of illness
•Confirmed Zika virus disease
Suspected case with positive laboratory results (RT-PCR)
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17. Differential diagnosis
•Dengue
•Chikungunya
•Leptospirosis
•Measles
•Rubella
•Parvovirus
•Scrub typhus
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18. Clinical features- Zika ,Dengue and Chikungunya
Features Zika Dengue Chikungunya
Fever ++ +++ +++
Rash +++ + ++
Conjunctivitis ++ - -
Arthralgia ++ + +++
Myalgia + ++ +
Headache + ++ ++
Hemorrhage - ++ -
Shock - + -
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19. Diagnosis
 Samples- Blood, urine, semen
• Nucleic acid testing-
RT-PCR- <7 days (serum)
7-20 days (urine)
• Serology
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20. Prevention and Control
I. Individual level
1. Management of general case
• Self limiting
• No specific antiviral or vaccine
• Symptomatic management
-Rest
-Plenty of oral fluids
-Management of fever and pain
• Isolation of cases under bed net
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21. Prevention and Control (continued)
2. Management in pregnant women
•Ongoing transmission- Lab testing
•Symptomatic pregnant females
-Early medical care
-Regular follow up ultrasound scan- microcephaly, developmental
abnormality
-Counselling – possible adverse effects, option for termination
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22. Prevention and Control (continued)
II. Family level
1. Source reduction
2. Use mosquito repellents
3. Wear light coloured full sleeve dress
4. Household screens- windows/doors
5. Bed nets-daytime - infants and children
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23. Prevention and Control (continued)
III. Community level
1. Source reduction- DRY DAY
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Day Place
Thursday JHI visits 50 houses –
Vector survey
Friday Schools
Saturday Offices, shops, other
establishments
Sunday Houses

24. Prevention and Control (continued)
2. Vector surveillance
Larval surveys
• House index
• Container index
• Breteau index
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25. Prevention and Control (continued)
3. Chemical control
a) Larvicide –Temephos
b) Adulticide –Only during outbreak
Integrated vector management
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26. Prevention and Control (continued)
IV. International airports and seaports
1. Quarantine and isolation facilities
2. Aircraft disinfection
3. WHO- IHR- Aedes aegypti index=0
(400 m)
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27. SUMMARY
•Arboviral disease- transmitted by Aedes mosquito
•1 in 4 symptomatic
•Symptoms include- Fever, rash, conjunctivitis, arthralgia, headache
•Mild- 2 to 7 days; few- complications
•Pregnant females and fetus at risk
•Symptomatic management
•Prevention- mosquito control
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