zika%20virus%20infection
ZIKA VIRUS INFECTION

Zika virus is an icosahedral, enveloped, single-stranded RNA virus that come from the Flaviviridae family & genus Flavivirus.

It is transmitted in humans through a bite of Aedes aegypti & Aedes albopictus mosquito.

In February 2016, the Zika virus infection was declared by the World Health Organization (WHO) as an international health emergency.

Pregnant women infected by Zika virus may pass their infection to the developing fetus & may cause birth defects such as microcephaly, ventriculomegaly, intracranial calcifications, extra-axial fluid, polymicrogyria, decreased brain parenchymal volume, hypoplasia of the cerebellum, brainstem or dermis, delayed myelination, thinning or hypoplasia of the corpus callosum & cortical atrophy & malformation.

 

 

Differential Diagnosis

  • Dengue fever
    • Zika virus and dengue virus infections have similar clinical manifestations and are both transmitted by the same mosquito vector
    • In dengue, the fever is usually high-grade, muscle pain is severe and not usually associated with conjunctivitis
    • In Zika, the fever is usually mild and acute in onset, muscle pain is mild and usually associated with non-bacterial conjunctivitis
    • Both infections may present with headache
  • Chikungunya
    • Both Zika and chikungunya have similar manifestations and mosquito vector
    • In chikungunya, the fever is high associated with intense joint pain in the hands, feet, knees and back, as well as conjunctivitis
    • Some patients with chikungunya may not be able to bend or walk or even perform simple task
  • Leptospirosis
    • May present with fever, rigor, myalgia, conjunctival suffusion, headache and jaundice
    • Patients with Zika virus infection does not present with jaundice
  • Malaria
    • Characterized by fever, nausea and vomiting, myalgia, malaise, abdominal pain, diarrhea and anemia
    • Establishment of the diagnosis is through the visualization of parasites on peripheral smear
  • Measles
    • Also present with fever, cough, sore throat, coryza, conjunctivitis and lymphadenitis
    • Koplik spots precedes generalized rash which is absent in patients with Zika virus infection
  • Rickettsia
    • Patients with Rickettsia have similar symptoms with Zika virus
    • But the characteristic presence of an eschar at the tick-bite site of inoculation with associated lymphadenopathy in Rickettsia is not present in Zika
  • Group A Streptococcus (GAS)
    • Group A streptococcus causes skin and soft tissue infections (eg cellulitis, erysipelas, pyoderma, injection drug use, burns, varicella virus infection and spontaneous gangrenous myositis)
    • Zika virus infection does not cause soft tissue infections and the symptoms are usually milder
  • Rubella
    • Characteristics of rubella are coryza, pinpoint and pink maculopapular rash that begins on the face then spreads caudally to the trunk and extremities that becomes generalized within 24 hours, arthritis (primarily involves the knees, wrists and fingers) and lymphadenopathy (involvement of the posterior cervical, posterior auricular, and suboccipital lymph nodes) that concurrently occur with low-grade fever
    • In Zika virus infection, the arthralgia may be noted on the small joints of the hands and feet while the rashes are characterized by pruritic macules and papules that appear on the trunk, extremities, palms and soles
    • Zika virus infection also presents with low-grade fever but without lymphadenopathy
  • Parvovirus
    • May present with acute and symmetric arthralgia or arthritis (involvement of the small joints of the hands, wrists, knees and feet)
    • Rash in parvovirus may be present or absent while in Zika maculopapular rashes are present
  • Other viruses that may be considered in ruling out Zika virus infection:
    • Enterovirus
    • Adenovirus
    • Alphavirus (eg Mayaro, Ross River, Barmah Forest, o'nyong-nyong and sindbis virus)
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