Zika

Question 1

Why is it called Zika?

Answer 1

• it comes from the Zika forest
• identified in 1947 from studying a rhesus monkey
• it means overgrown

Question 2

Zika epidemiology?

Answer 2

• first isolated from a monkey in Uganda in 1947
• prior to 2007, only sporadic human disease cases reported from Africa and Southeast Asia
• In 2007, first outbreak reported on Yap island, Federated States of Micronesia
• In 2013-2014, more than 28,000 suspected cases reported in French Polynesia

Question 3

Zika virus vectors?

Answer 3

1. Aedes species mosquitoes
   - Aedes aegypti more efficient vectors for humans
   - Aedes albopictus
2. also transmit yellow fever, dengue and chikungunya viruses
3. lay eggs in domestic water holding containers
4. live in and around households
5. aggressive daytime biters

Question 4

Location of mosquito populations? (10)

Answer 4

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Question 5

Criteria for an outbreak?

Answer 5

• infected person must enter USA
• vector should bite the person during viremic phase
• vector should live long enough for the virus to multiply and infect another person
• cycle needs to continue over time

Question 6

Life span and flight range of Aedes aegypti?

Answer 6

• life span 30 days
• flight range 150 meters
• cockroach of mosquitos

Question 7

Zika virus transmission cycle? (12)

Answer 7

• Africa, slyvatic, jungle cycle between nonhuman primates and forest dwelling species
• urban setting- human to mosquito to human

Question 8

Vector competence?

Answer 8

intrinsic ability to biologically transmit a pathogen

Question 9

Vectoral capacity?

Answer 9

ability of a vector to transmit a pathogen in a given location and at a specific time

Question 10

What did PHEIC declare?

Answer 10

• WHO declared it an extraordinary event of 2/1/16
• clusters of microcephaly and other neurological disorders
• constitutes a health risk through international spread
• coordinated response (as it is unexpected, serious and unusual)
• implications beyond the affected country

Question 11

How does a mosquito spread a virus? (15)

Answer 11

• mosquito bites infected person and gets infected
• spreads it to other people

Question 12

Symptoms of Zika?

Answer 12

• fever
• rash
• joint pain
• conjunctivitis (red eyes)

Question 13

How can Zika be transmitted person to person?

Answer 13

1. Maternal to fetal
   - intrauterine
   - perinatal
2. sexual transmission
   - and non sexual transmission
   - blood transfusion
3. lab exposure
4. theoretical
   - organ or tissue transplant
   - breast milk

Question 14

Zika virus incidence and attack rates?

Answer 14

• infection rate 73%
• symptomatic attack rate among infected, 18%
• all age groups affected
• adults more likely to present for medical care
• no severe diseases, hospitalizations, or deaths

Question 15

Zika virus clinical disease course and outcomes?

Answer 15

• clinical illness usually mild
• symptoms last several days to weeks
• severe disease requiring hospitalization uncommon
• fatalities rare
• GBS reported in patients following zika (relationship not known)

Question 16

Zika and microcephaly in Brazil?

Answer 16

• reports of increase of number of babies born with microcephaly in 2015 in Brazil
• zika virus infection identified in several infants born with microcephaly (including deaths) and in early fetal loss (some tested negative for zika, had microcephaly)

Question 17

What is good test for Zika?

Answer 17

urine because it stays in urine for 14 days

Question 18

Diagnostic testing for Zika?

Answer 18

• reverse transcriptase PCR for viral RNA in serum collected less than 7 days after onset
• serology for IgM and neutralizing antibodies in serum collected over 4 days after onset
• plaque reduction neutralization test (PRNT)
• immunohistochemical (IHC) staining for viral antigens

Question 19

Serology cross reactions with other flaviviruses?

Answer 19

• Zika virus serology (IgM) can be positive due to antibodies against related flaviviruses (dengue and yellow fever)
• neutralizing antibody testing may discriminate between cross reacting antibodies in primary flavivirus infections
• difficult to distinguish infecting virus in people previously infected with or vaccinated against a related flavivirus
• healthcare providers should work with state and local health departments to ensure test results are interpreted correctly

Question 20

Initial assessment and treatment?

Answer 20

• no specific antiviral therapy
• treatment is supportive (rest, fluids, analgesics, antipyretics)
• suspected Zika virus infections should be evaluated and managed for possible dengue or chikungunya virus infections
• non steroidal should be given (tylenol)
• aspirin and NSAIDS should be avoided until dengue is ruled out to avoid hemorrhage

Question 21

What other viruses are hard to distinguish from Zika? (29)

Answer 21

• dengue
• chikungunya

Question 22

Zika virus disease surveillance?

Answer 22

• consider in travelers with acute onset of fever, rash, arthralgia, or conjunctivitis within 2 weeks of return
• inform and evaluated women who traveled to areas with Zika transmission while pregnant
• evaluate fetuses/infants of women infected during pregnancy for possible congenital infection and microcephaly
• be aware of areas with Aedes species mosquitos

Question 23

Zika virus and pregnancy?

Answer 23

• limited info available
• no evidence of increased susceptibility
• infection can occur in any trimester
• incidence of Zika in this population is not known
• no evidence of more severe disease
• edema
• rash

Question 24

Maternal fetal transmission of Zika?

Answer 24

• evidence of maternal fetal transmission:
• zika infection confirmed in infants with microcephaly in brazil and in infants whose mothers have traveled to brazil but delivered in US
• zika RNA identified in specimens of fetal losses
• zika detected prenatally in amniotic fluid
• pregnant women should be tested
• wear permethrin treated clothes

Question 25

What is microcephaly? causes? (39)

Answer 25

- small head- occipital frontal circumference below third percentile - causes: - genetic - nutritional - environmental toxins - TORCH agents vascular drugs - radiation

Question 26

What else can an infant have a problem with zika?

Answer 26

- eye problems - limb spasms at birth

Question 27

How long can zika persist in semen? (52)

Answer 27

up to 6 months

Question 28

Zika and GBS? (48)

Answer 28

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Question 29

late sexual transmission? (51)

Answer 29

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Question 30

congenital zika syndrome?

Answer 30

- craniofacial malformations - flat nasal bridge - anteverted nares - limb deformities - calcifications and skin folds, skull asymmetry

Question 31

Arthogryposis?

Answer 31

joint contractures at birth -crooked joint

Question 32

What can happen to platelets in zika?

Answer 32

- thrombocytopenia (low platelets) - alveolar and intracranial hemorrhage

Question 33

Zika kit?

Answer 33

- literature - mosquito repellant - mosquito netting - condoms - oral digital thermometer - tablets to kill mosquito larvae in standing water

Question 34

Zika preventive measures?

Answer 34

- no vaccine or medication to prevent infection - primary prevention is to reduce mosquito exposure - pregnant women should consider postponing travel to areas with outbreaks - protect infected people form mosquito exposure during first week of illness to prevent further transmission

Question 35

What is DEET?

Answer 35

- 20% - can provide 10 hours of protection (permethrin)

Question 36

Potential outbreak areas in US?

Answer 36

- mostly florida - up the east coast

Question 37

Zika dynamics? (69)

Answer 37

- R\<1 means that one infected person in infecting less than one person, virus will not spread - R\>1 virus will spread - measles \> 18, highly contagious

Question 38

Capacity of A. albopictus to spread zika?

Answer 38

- doesnt spread it yet - could down the road

Question 39

Risk of microcephaly at different stages?

Answer 39

- earlier risk is higher - there is risk through the whole process

Question 40

Summary of Zika? (72)

Answer 40

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