Epidemiologic review of Zika virus disease

Abstract

Zika virus disease has resonated great concern globally. The World Health Organization declared it “a public health emergency of International concern” on 1st February, 2016. The recent outbreaks have become a major challenge due to a drift from its earlier known benign exanthematous spectrum to a causal link to microcephaly. Historically, the name Zika virus comes from the Zika Forest of Uganda. It was first identified in 1947 among Rhesus Macaque sub-population. Two genetically distinct isolates have been well characterized; the Asian and African strains. This virus is spread by bites of day-time-active Aedes mosquitoes; the Aedes aegypti and Aedes albopictus. Zika Virus appears to spread along a narrow equatorial belt of Africa to Asia through the Pacific Ocean to French Polynesia, New Caledonia (southwest Pacific Ocean), the Cook Islands (south Pacific), and Easter Island (a Chilean territory in Polynesia), and most recently to Mexico, Central America, the Caribbean, and South America, where today has assumed a pandemic proportion.

Up to eighty percent of infections are asymptomatic. Symptomatic infections are characterized by a self-limiting febrile illness and maculopapular rash, arthralgia, conjunctivitis, back pain and mild headaches. Maternal Zika viral load is thought to be a significant risk factor to fetal infection leading to invasion of either trophoblasts or placental cells or both through maternal decidua. Zika viral RNA proteins and associated extensive selective tissue injuries have been demonstrated in the brains and spinal cords of abortuses. Diagnosis of Zika virus is essentially based on viral RNA detection from clinical specimens. Currently, licensed preventive medicines or vaccines are unavailable. With the wide spate of recent outbreaks and consequent neurologic morbidity and mortality, there is need for deployment of point-of-care equipment for screening of pregnant women in our environment. This is an ambitious call for advocacy by all relevant health care providers.

Keywords: Zika Virus, disease outbreaks, microcephaly, Aedes mosquitoes