Epsilon Archive for Student Projects

Abstract

There is a vast selection of vector-borne diseases circulating in the world today. The latest of these
to have a globally recognised impact is the Zika Virus (ZIKV). The suggested link between
ZIKV and the recent spike in microcephaly in Brazil has put the spotlight on this previously obscure
virus. The potential for this virus to spread worldwide means that any suggested correlation
between ZIKV and negative health effects should be extensively researched in case of a future
global epidemic. This literature-review aims to assess how ZIKV is transmitted, through which
vectors, it’s capacity for non-vector borne transmission, as well as highlighting the potential risks
it poses to human health.
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ZIKV is named after the Zika forest in Uganda where it was discovered in 1947, first isolated in a
Rhesus monkey whilst studying yellow fever virus. The virus would for the next few decades go
relatively undetected, with minor activity being reported in Africa and Asia, until 2007 when an
outbreak occurred in Yap, Micronesia. Since then, epidemics have been observed in French Polynesia
in 2013 and Brazil in 2016, with the virus being linked to both microcephaly and Guillain-
Barré syndrome (GBS).
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The Zika virus is of the Flaviviridae family, and so is related to Dengue virus, yellow fever virus
and West Nile virus. It produces very similar febrile symptoms to some more commonly diagnosed
arboviral infections such as chikungunya (CHIKV) and dengue virus (DENV), which has
been suggested as a delaying factor in diagnosis. The low number of ZIKV cases previously
recorded may be due to the occurrence of subclinical forms of ZIKV, as well as misdiagnosis as
DENV or CHIKV.
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Transmission of ZIKV is mostly vectorial through mosquitoes of the Aedes genus. The virus reproduces
in the host vector with no effect on the host, and remains in the host until it dies. The
Aedes aegypti and Aedes albopictus are the species most competent of transmission and pose a
great public health concern, due to them being widely spread throughout tropical, sub-tropical
(Ae. aegypti) and temperate (Ae. albopictus) regions. Non-vector borne transmission has also
been described, with sexual, perinatal and blood transfusion-transmitted ZIKV all reported, although
much less common than vector-borne transmission.
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As mentioned previously, ZIKV has been linked to microcephaly and Guillain-Barré syndrome.
The current ZIKV outbreak in Brazil has coincided with a spike in the number of babies born
with microcephaly. Although not yet a proven link, pregnant women in the regions are being
urged to take preventative measures against infection. Guillain-Barré syndrome has however already
been shown to be a possible result of ZIKV infection. As ZIKV is rapidly spreading across
the Americas, these countries’ healthcare systems must be prepared to accommodate patients with
the potential complications that infection with the virus may lead to.