Zika Virus
Zika virus was first identified in the Zika forest of Entebbe, Uganda in 1947 when a group of
scientists examined a febrile rhesus monkey for Yellow fever. This infectious disease has been
linked to incidences of microcephaly (babies being born with underdeveloped brains),
Guillain-Barré syndrome, myelitis, and other neurologic conditions
What is Zika virus?
Zika virus is a mosquito-borne flavivirus that is transmitted to humans primarily through the bite
of an infected Aedes species mosquito (Aedes aegypti and Aedes albopictus).
● The Zika virus (ZIKV) is a member of the Flaviviridae virus family and the Flavivirus
genus.
● In most cases, Zika virus infection causes a mild, self-limited illness.
● The incubation period is likely 3-12 days.
● The spectrum of Zika virus disease overlaps with other that of arboviral infections,
but rash (maculopapular and likely immune-mediated) typically predominates.
● In April 2016, a deputy director at the Centers for Disease Control and Prevention
(CDC) warned that the risk of Zika virus infection in the United States may have been
previously underestimated, citing the increased range of the mosquito vectors (now
in 30 US states, up from 12 as previously thought) and the travel risks associated
with the 2016 Olympics in Brazil.
● Nonhuman and human primates are likely the main reservoirs of the virus, and
anthroponotic (human-to-vector-to-human) transmission occurs during outbreaks.
Pathophysiology
Zika virus is well-adapted to grow in various hosts, ranging from arthropods to vertebrates.
● Viral attachment to unidentified cellular receptors is mediated by the E (envelope)
glycoprotein.
● This is followed by endocytic uptake and then uncoating of the nucleocapsid and
release of viral RNA into the cytoplasm.
● A viral polyprotein is produced and modified by the endoplasmic reticulum.
● Immature virions collect both in the endoplasmic reticulum and in secretory vesicles
before being released.
, Causes
Zika virus is transmitted to people primarily through the bite of an infected Aedes species
mosquito (Ae. aegypti and Ae. albopictus).
● Mosquitoes. A mosquito gets infected with a virus when it bites an infected person
during the period of time when the virus can be found in the person’s blood, typically
only through the first week of infection; infected mosquitoes can then spread the
virus to other people through bites.
● Infected pregnant mother to child. A pregnant woman already infected with Zika
virus can pass the virus to her fetus during the pregnancy or around the time of birth.
● Through sex. Zika can be passed through sex from a person who has Zika to his or
her partners; Zika can be passed through sex, even if the infected person does not
have symptoms at the time.
● Through blood transfusion. There have been multiple reports of possible blood
transfusion transmission cases in Brazil.
● Through lab and healthcare setting exposure. There are reports of laboratory
acquired Zika virus infections, although the route of transmission was not clearly
established in all cases.
Statistics and Incidences
The global prevalence of Zika virus infection has not been widely reported owing to
asymptomatic clinical course, clinical resemblance to other infection with other flaviviruses
(dengue, chikungunya), and difficulty in confirming diagnosis.
● In 2015 and 2016, large outbreaks of Zika virus occurred in the Americas, resulting in
an increase in travel-associated cases in US states, widespread transmission in
Puerto Rico and the US Virgin Islands, and limited local transmission in Florida and
Texas.
● Based on sporadic case reports, entomological surveys, and seroprevalence
surveys, Zika virus infection had been reported in various hosts, including humans,
primates, and mosquitoes, in 14 countries across Africa, Asia, and Oceania, as of
2014.
● In May 2015, Brazil reported the first outbreak of Zika virus infection in the Americas.
● the Brazil Ministry of Health estimated around 440,000-1,300,000 suspected cases of
Zika virus infection in December 2015.
● In March 2016, the WHO reported that Zika virus was actively circulating in 38
countries and territories, 12 of which have reported an increase in GBS cases or
laboratory evidence of Zika virus among patients with GBS.
Zika virus was first identified in the Zika forest of Entebbe, Uganda in 1947 when a group of
scientists examined a febrile rhesus monkey for Yellow fever. This infectious disease has been
linked to incidences of microcephaly (babies being born with underdeveloped brains),
Guillain-Barré syndrome, myelitis, and other neurologic conditions
What is Zika virus?
Zika virus is a mosquito-borne flavivirus that is transmitted to humans primarily through the bite
of an infected Aedes species mosquito (Aedes aegypti and Aedes albopictus).
● The Zika virus (ZIKV) is a member of the Flaviviridae virus family and the Flavivirus
genus.
● In most cases, Zika virus infection causes a mild, self-limited illness.
● The incubation period is likely 3-12 days.
● The spectrum of Zika virus disease overlaps with other that of arboviral infections,
but rash (maculopapular and likely immune-mediated) typically predominates.
● In April 2016, a deputy director at the Centers for Disease Control and Prevention
(CDC) warned that the risk of Zika virus infection in the United States may have been
previously underestimated, citing the increased range of the mosquito vectors (now
in 30 US states, up from 12 as previously thought) and the travel risks associated
with the 2016 Olympics in Brazil.
● Nonhuman and human primates are likely the main reservoirs of the virus, and
anthroponotic (human-to-vector-to-human) transmission occurs during outbreaks.
Pathophysiology
Zika virus is well-adapted to grow in various hosts, ranging from arthropods to vertebrates.
● Viral attachment to unidentified cellular receptors is mediated by the E (envelope)
glycoprotein.
● This is followed by endocytic uptake and then uncoating of the nucleocapsid and
release of viral RNA into the cytoplasm.
● A viral polyprotein is produced and modified by the endoplasmic reticulum.
● Immature virions collect both in the endoplasmic reticulum and in secretory vesicles
before being released.
, Causes
Zika virus is transmitted to people primarily through the bite of an infected Aedes species
mosquito (Ae. aegypti and Ae. albopictus).
● Mosquitoes. A mosquito gets infected with a virus when it bites an infected person
during the period of time when the virus can be found in the person’s blood, typically
only through the first week of infection; infected mosquitoes can then spread the
virus to other people through bites.
● Infected pregnant mother to child. A pregnant woman already infected with Zika
virus can pass the virus to her fetus during the pregnancy or around the time of birth.
● Through sex. Zika can be passed through sex from a person who has Zika to his or
her partners; Zika can be passed through sex, even if the infected person does not
have symptoms at the time.
● Through blood transfusion. There have been multiple reports of possible blood
transfusion transmission cases in Brazil.
● Through lab and healthcare setting exposure. There are reports of laboratory
acquired Zika virus infections, although the route of transmission was not clearly
established in all cases.
Statistics and Incidences
The global prevalence of Zika virus infection has not been widely reported owing to
asymptomatic clinical course, clinical resemblance to other infection with other flaviviruses
(dengue, chikungunya), and difficulty in confirming diagnosis.
● In 2015 and 2016, large outbreaks of Zika virus occurred in the Americas, resulting in
an increase in travel-associated cases in US states, widespread transmission in
Puerto Rico and the US Virgin Islands, and limited local transmission in Florida and
Texas.
● Based on sporadic case reports, entomological surveys, and seroprevalence
surveys, Zika virus infection had been reported in various hosts, including humans,
primates, and mosquitoes, in 14 countries across Africa, Asia, and Oceania, as of
2014.
● In May 2015, Brazil reported the first outbreak of Zika virus infection in the Americas.
● the Brazil Ministry of Health estimated around 440,000-1,300,000 suspected cases of
Zika virus infection in December 2015.
● In March 2016, the WHO reported that Zika virus was actively circulating in 38
countries and territories, 12 of which have reported an increase in GBS cases or
laboratory evidence of Zika virus among patients with GBS.
