Zika Flashcards
Why is it called Zika?
- it comes from the Zika forest
- identified in 1947 from studying a rhesus monkey
- it means overgrown
Zika epidemiology?
- 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
Zika virus vectors?
- Aedes species mosquitoes
- Aedes aegypti more efficient vectors for humans
- Aedes albopictus - also transmit yellow fever, dengue and chikungunya viruses
- lay eggs in domestic water holding containers
- live in and around households
- aggressive daytime biters
Location of mosquito populations? (10)
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Criteria for an outbreak?
- 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
Life span and flight range of Aedes aegypti?
- life span 30 days
- flight range 150 meters
- cockroach of mosquitos
Zika virus transmission cycle? (12)
- Africa, slyvatic, jungle cycle between nonhuman primates and forest dwelling species
- urban setting- human to mosquito to human
Vector competence?
intrinsic ability to biologically transmit a pathogen
Vectoral capacity?
ability of a vector to transmit a pathogen in a given location and at a specific time
What did PHEIC declare?
- 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
How does a mosquito spread a virus? (15)
- mosquito bites infected person and gets infected
- spreads it to other people
Symptoms of Zika?
- fever
- rash
- joint pain
- conjunctivitis (red eyes)
How can Zika be transmitted person to person?
- Maternal to fetal
- intrauterine
- perinatal - sexual transmission
- and non sexual transmission
- blood transfusion - lab exposure
- theoretical
- organ or tissue transplant
- breast milk
Zika virus incidence and attack rates?
- 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
Zika virus clinical disease course and outcomes?
- 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)
Zika and microcephaly in Brazil?
- 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)
What is good test for Zika?
urine because it stays in urine for 14 days
Diagnostic testing for Zika?
- 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
Serology cross reactions with other flaviviruses?
- 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
Initial assessment and treatment?
- 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
What other viruses are hard to distinguish from Zika? (29)
- dengue
- chikungunya
Zika virus disease surveillance?
- 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
Zika virus and pregnancy?
- 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
Maternal fetal transmission of Zika?
- 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
What is microcephaly? causes? (39)
- small head- occipital frontal circumference below third percentile
- causes:
- genetic
- nutritional
- environmental toxins
- TORCH agents vascular drugs
- radiation
What else can an infant have a problem with zika?
- eye problems
- limb spasms at birth
How long can zika persist in semen? (52)
up to 6 months
Zika and GBS? (48)
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late sexual transmission? (51)
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congenital zika syndrome?
- craniofacial malformations
- flat nasal bridge
- anteverted nares
- limb deformities
- calcifications and skin folds, skull asymmetry
Arthogryposis?
joint contractures at birth
-crooked joint
What can happen to platelets in zika?
- thrombocytopenia (low platelets)
- alveolar and intracranial hemorrhage
Zika kit?
- literature
- mosquito repellant
- mosquito netting
- condoms
- oral digital thermometer
- tablets to kill mosquito larvae in standing water
Zika preventive measures?
- 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
What is DEET?
- 20%
- can provide 10 hours of protection (permethrin)
Potential outbreak areas in US?
- mostly florida
- up the east coast
Zika dynamics? (69)
- 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
Capacity of A. albopictus to spread zika?
- doesnt spread it yet
- could down the road
Risk of microcephaly at different stages?
- earlier risk is higher
- there is risk through the whole process
Summary of Zika? (72)
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