What is Zika Virus?

What is Zika Virus?

The Zika Virus (ZIKV) is an arbovirus that carries the name of a forest near Kampala, Uganda. The virus was first identified in rhesus monkeys in 1947 and further isolated in humans in Uganda and Tanzania in 1952. The transmission is mostly vectorial by mosquito species, namely Aedes Egypti (also known as spread dengue virus and chikungunya virus). In addition, direct interhuman transmission has been documented through intrauterine transmission resulting in congenital infection, intrapartum transmission from a viremic mother to her newborn, sexual transmission and blood transfusion. During outbreaks, humans are primarily amplifying host for Zika Virus. An estimated 80% of persons who are infected with Zika virus are asymptomatic. The symptomatic disease generally is mild and characterised by acute onset of fever, maculopapular rash, arthralgia, or nonpurulent conjunctivitis. Symptoms usually last for several days to one week.

Clinical Symptoms and Diagnostic Algorithm

Approximately 20% of ZIKV infected individuals become symptomatic lasting for several days to a week. Charasteric clinical findings are acute onset of fever with maculopapular rash, arthralgia, or conjunctive myalgia and headache.

The Diagnosis of Zika virus infection can be made through both molecular and serological testing. Molecular testing is the preferred test (which is useful to detect the virus only in the initial days of an acute infection). This includes reverse transcription – polymerase chain reaction (RT – PCR) for viral RNA and should be performed on serum specimens. To detect congenital infections, serum samples should be collected from the umbilical cord or directly from the infant within 2 days of birth.

IgM ELISA for Zika virus and Dengue virus should be performed on infant serum, infant CSF, and maternal serum; however, results of these assays can be falsely positive of cross-reacting antibodies.

Tiered Algorithm for suspected cases of Chikungunya, Dengue, or Zika infection.

PRNT’: Plaque reduction neutralization tests
*Testing as per this algorithm

  • Due to extensive cross-reactivity in flavivirus serological assays, for samples collected < 7 days post illness onset, molecular detection should be performed first.
  • Perform if sample > 4 days after symptoms after symptoms onset
  • Extensive cross-reactivity would be expected in samples from DENV/ZIKV circulation areas. A positive IgM assay with either antigen should be confirmed by using PRNT both ZIKV anf
  • DENV as well as any other flavivirus (eg: SLEV, ZIKV, WNV, etc.) that might be found in the geographic area (including travel areas)
  • PRNT should include any flavivirus (eg: SLEV, ZIKV, WNV, etc.) that might be found in the geographic area (including travel areas)
  • Management of ZIKV infections

    No specific antiviral treatment is available for Zika virus infections and no vaccine against Zika virus available. In the case of infants with congenital ZIKV infections, treatment is supportive and should address specific neurodevelopmental issues.