Zika Flashcards
Zika - organism
Single stranded RNA virus
Flavivirus genus - flaviviridae family - similar to dengue, yellow fever
Two strains:
African and Asia
[Asian strain responsible for outbreaks]
Zika - burden
40,000 reported cases
Greatest number in South and Central America [Brazil highest number]
Zika - transmission
Aedes aegypti [primary vector]
Aedes albopictus [secondary vector - wider distribution - more northern distribution]
Other forms of transmission:
-Sexual
-Blood transfusion
-Transplacental
Zika - clinical features
IP 3-12 days
80% asymptomatic
Rash and fever most common:
-Arthralgia
-Conjunctivitis [non-purulent]
-Myalgia
-Headache
-Back pain
Mild, self-limiting
Zika - congenital zika syndrome
Microcephaly is key marker
Asian strain linked to congenital zika syndrome
Highest risk during 1st and 2nd trimester
Multi-organ phenotype:
-Craniofacial disproportion, pointed occiput, redundant scalp skin, cerebral calcifications, diaphragmatic paralysis
Eyes:
-Focal retinal mottling, cataracts, glaucoma, optic nerve atrophy
Zika - neurological complications
Guillain-Barre syndrome:
-incidence 1 per person 100,000 years
-Can occur with dengue, chikungunya, campylobacter
-24 cases per 100,000 persons infected with Zika
-Post-infectious
-More common in male 20-40yrs
-Median of 6 days from onset
Rare:
-Myelitis
-Encephalitis
-Optic neuritis
Zika - diagnosis
PCR:
-Short viraemic period [3-5 days after onset of symptoms]
-Pregnant women have longer viraemic period
-Urine sample - positive for longer
Serology:
-Zika specific IgM and IgG antibodies
-IgM - positive in first week after symptom onset
-IgG - appears early, may persist for years, possibly lifelong
-Cross-reactivity with other flaviviruses
Zika - pregnancy advice
If planning a pregnancy:
-Don’t travel to Zika endemic area
-Avoid pregnancy for 2 months if only woman has travelled
-Avoid pregnancy for 3 months if both partnets/just male has travelled
If already pregnant:
-Use barrier contraception
