ZiKa Virus (ZKV)disease is an emerging mosquito-borne human viral infection that has been ecologically
associated with congenital microcephaly in newborns in Brazil. The general
public is therefore advised to take precautions to reduce the risk of infection
for example: protecting yourself from mosquito bites by wearing long-sleeved
shirts and trousers and keeping doors and windows screened. Pregnant women are advised
to: prevent contact with people traveling from Brazil showing signs of fever/infection,
use pregnancy compatible mosquito repellents and avoid environmental exposures
to chemicals or consumption of teratogenic drugs.
Congenital microcephaly
means the newborn’s head falls below its normal circumference for its gestational
age, sex and race. The small head is the result of a neurodevelopmental disorder
and can be monitored prenatally using ultrasound machines.
The virus (ZKV)
was first isolated in Uganda in 1947 and has since been reported in tropical
areas of western Africa (Nigeria, Sierra Leone, Ivory Coast, Cameroon and Senegal)
and of central Africa (Gabon, Uganda and Central African Republic), in Asia
(Pakistan, Indonesia, Philippines, Malaysia, Cambodia and Thailand) and in
several islands of the pacific region since 2007 (Micronesia, Cook Islands,
French Polynesia, New Caledonia, Guam, Samoa, Vanuatu and Solomon Islands). The
latest (2014) cases of ZKV infection have been reported in the Americas (North-eastern
Brazil in the states of Bahia, Maranhao, Pernambuco, Rio Grande do Norte,
Paraíba and Sergipe). A total of 14835 cases of acute exanthematous illness
have been reported in 12 health districts of Salvador – the third city of Brazil
– between 15 February 2015 and 25 June 2015 with an overall attack rate of 5.5
cases/10 000 inhabitants). The expansion of the ZIKV infections to South
America constitutes a significant development in the epidemiology of this
emerging vector-borne disease.
ZKV dis is caused
by Zika virus (ZIKV), a flavivirus
from the Flaviviridae family and
Spondweni serocomplex. The virus was first identified in 1947 in the Zika forest in Uganda in the rhesus macaque population.
Mosquitoes
remain the main transmitters of the disease with the Aedes mosquitoes (Aedes
aegypti, Aedes hensilii and Aedes
albopictus) being highly implicated.
There is also
evidence that prenatal transmission can occur via the placenta or during the
delivery of a viraemic mother. ZIKV transfusion-derived transmission is theoretically
possible. Possible cases of sexual transmission of ZIKV have been reported but
these three modes of transmission are rare.
The
incubation period of the infection ranges from 3 to 12 days. The disease
symptoms are usually mild and last for 2 to 7days. Infection may go
unrecognized or be misdiagnosed as dengue, chikungunya or other viral
infections giving fever and rash. Asymptomatic infections are common and only
one in four people infected with ZIKV are believed to develop symptoms.
The main
symptoms of ZIKV disease include:
- low-grade fever (<38.5°C)
- transient arthritis/arthralgia with possible joint swelling mainly in the smaller joints of the hands and feet.
- maculo-papular rash often spreading from the face to the body
- conjunctival hyperaemia or bilateral non-purulent conjunctivitis (Red eyes)
- General non-specific symptoms such as myalgia (muscle pains), asthenia and headaches.
Association
with neurological complications is still under investigation ad there has
however been no deaths associated with ZKV infection to date.
Dr.
Moses Bwana
Post-grad
at the University of Nairobi [Applied Microbiology]
Cell: +254729246187; Email: bwanamoses@gmail.com
