Zika virus disease

• Zika is spread mostly by the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus).
• These mosquitoes bite during the day and night.
• Zika can be passed from a pregnant woman to her fetus. Infection during pregnancy can cause certain birth defects.
• There is no vaccine or medicine for Zika.

Digitally-colorized transmission electron micrograph (TEM) of Zika virus

Modes of Transmission

Zika virus is a single-stranded RNA virus of the Flaviviridae family, genus Flavivirus.

A conceptual figure of Zika virus transmission routes

Transmission

• Zika virus is transmitted to humans primarily through the bite of an infected Aedes species mosquito such as aedes aegypti and aedes albopictus).
• The mosquito vectors typically breed in domestic water-holding containers; they are aggressive daytime biters and feed both indoors and outdoors near dwellings.
• Nonhuman and human primates are likely the main reservoirs of the virus, and anthroponotic (human-to-vector-to-human) transmission occurs during outbreaks.
• Perinatal, in utero, and possible sexual and transfusion transmission events have also been reported.

Zika virus infections worldwide

Clinical Signs & Symptoms

• Many people infected with Zika virus are asymptomatic.
• Characteristic clinical findings are acute onset of fever with maculopapular rash, arthralgia, or conjunctivitis.
• Other commonly reported symptoms include myalgia and headache.
• Clinical illness is usually mild with symptoms lasting for several days to a week.
• Severe disease requiring hospitalization is uncommon and case fatality is low.
• Due to concerns of microcephaly caused by maternal Zika virus infection, fetuses and infants of women infected with Zika virus during pregnancy should be evaluated for possible congenital infection and neurologic abnormalities.

Zika Virus

Diagnosis

• Based on the typical clinical features, the differential diagnosis for Zika virus infection is broad.
• In addition to dengue, other considerations include leptospirosis, malaria, rickettsia, group A streptococcus, rubella, measles, and parvovirus, enterovirus, adenovirus, and alphavirus infections (e.g., chikungunya, Mayaro fever, Ross River fever, Barmah Forest, o’nyong-nyong, and sindbis viruses).
• Preliminary diagnosis is based on the patient’s clinical features, places and dates of travel, and activities.
• Laboratory diagnosis is generally accomplished by testing whole blood, serum, or plasma to detect virus, viral nucleic acid, or virus-specific immunoglobulin M and neutralizing antibodies.

MICROCEPHALY

Notifiable in the US

As an arboviral disease, Zika virus is a nationally notifiable condition in the United States and many other countries worldwide.

Treatment

• No specific antiviral treatment is available for Zika virus disease.
• Treatment is generally supportive and can include rest, fluids, and use of analgesics and antipyretics.
• Because of similar geographic distribution and symptoms, patients with suspected Zika virus infections also should be evaluated and managed for possible dengue or chikungunya virus infection.
• Aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) should be avoided until dengue can be ruled out to reduce the risk of hemorrhage.
• People infected with Zika, chikungunya, or dengue virus should be protected from further mosquito exposure during the first few days of illness to prevent other mosquitoes from becoming infected and reduce the risk of local transmission.