BY MEGHA MANOJ MACHHAR

 It is a mosquito-borne viral infection, first identified in Rhesus monkey of Zika forest in Uganda in 1947, hence named Zika virus.  In humans it was first identified in 1952 in Uganda and United Republic of Tanzania and the virus was first isolated in Nigeria in  The sporadic cases of infection were reported in Southeast Asia and Sub-Saharan Africa.

 It is a member of Flavivirus family that also includes yellow fever virus, dengue virus, Japanese encephalitis and West Nile virus.  Its genome size is 10.8 kbp with positive strand RNA enclosed in capsid and surrounded by membrane.  The membrane has (E) glycoprotein envelope embedded in it that allows the attachment of viral particles to the host cell receptors to initiate infection.

 ZIKV moved out of Asia and Africa and caused an epidemic in YAP islands of Micronesia (2007) and French Polynesia, New Caledonia, The Cook Islands and in Easter Islands in 2013 and  In 2015 there has been an upsurge in ZIKV infection dramatically in America with Brazil being most affected; 444,000 to 1.3 million cases reported through December  It has been reported that ZIKV infection has spread to 23 countries across America.

 It is transmitted by mosquito bites, belonging to the genus Aedes, mainly Aedes agypti.  Other members include A.africanus, A.apicoargenteus, A.leuteocephalus, A.vitattus and A.furcifer.  A.albopictus was identified as the primary vector for ZIKV transmission during 2007 Gabon outbreak.

 The person infected with ZIKV develop mild symptoms that last for several days to a week.  The symptoms include fever, rash, joint pain, conjunctivitis, headache, malaise.  In general the high incidences of Gullian Barré syndrome and mirocephaly with rapid spread of the virus have made the outbreak more serious.

 The infection is diagnosed based on the symptoms developed after exposure to the virus particles via mosquito bites.  The laboratory confirmation can be done from the samples collected from blood and other body fluids like urine and saliva.

 The association of the syndrome with ZIKV was first observed during the French Polynesia outbreak in  It is an autoimmune disease which severely affects the peripheral nervous system that results in progressive muscle weakening.  It is a rare immune system disorder with a frequency of 0.4 to 4 people per 100,000 per year.  The exact cause of GBS is unknown but is known to be preceded by bacterial or viral infection.

 The first case of development of GBS seven days after contracting the ZIKV was observed in a Polynesian women.  As per the reports from WHO Brazil, Venezuela, Suriname, El Salvador and Colombia have observed a surge in GBS development with the occurrence of ZIKV.  Brazil has reported that out of confirmed cases of GBS 62% has developed symptoms of ZIKV infection.  The correlation of GBS and ZIKV is still unknown. Researches are being carried out to figure out the connection between the two.

 Like GBS, there has been an exorbitant rise in Microcephaly cases with the development of ZIKV.  Microcephaly is neonatal malformation where the newborn has reduced head size as compared to the normal head size of healthy infants.  The exact link between ZIKV and birth defects are yet to be discovered. Pregnant women are, thus, cautioned to avoid travelling to places with Zika virus outbreak.

 ZIKV can be transferred from mother to her fetus during pregnancy.  As per WHO, out of 79 reported deaths of infants due to congenital malformation ZIKA virus has been confirmed in the tissues of 5 fetuses in northeastern Brazil.  The reports by University of Sao Paulo have recorded ocular abnormalities in infants with microcephaly and ZIKV infection, from the state of Bahia, Brazil in 34.5% of infants with microcephaly.  The report has also documented that mothers of 79.3% of infants with microcephaly have shown symptoms of ZIKV infection.

 Another report have documented a case of 25 year old pregnant European lady working in Natal, Brazil who developed fetal anomalies including microcephaly at the 28 th week of gestation. Autopsy reports after termination of pregnancy revealed severe brain defects and nm viral particles were detected in brain by electron microscopy.  On sequencing the viral genome it has been found out that the viral particle had 99.7% similarity with genome of Zika virus isolated from a patient in French Polynesia during 2013 outbreak and a strain from Sao Paulo in 2015.

 There has been evidence of sexual transmission of ZIKV by men to his female counterparts. But there is no evidence if women could transmit the virus to their sex partners.  Two cases have been reported where man had shown symptoms.  More research is required in this matter. As a matter of concern, Centers for Disease Control and Prevention (CDC) have recommended the men who have lived or travelled to ZIKV infected areas to abstain from sexual activities.

 Potential measures should be taken to eliminate the mosquito breeding sites like water-filled buckets, flower-pots, gutters, open tyres etc.  Personal protection measures should be adopted like wearing light-colored clothes, covering the body to the maximum, using window screens, keeping doors and windows closed, sleeping under mosquito nets, etc.  Using mosquito repellants that contain DEET (N,N-diethyl-3-methlybenzamide), IR3535 (3-[N- acetyl-N-butyl]-aminopropionic acid ethly ester), Icaridin (1-piperidinecarboxylic acid, 2-(2- hydroxyethyl)-1-methylpropylester)

 Use of insecticides recommended by WHO Pesticide Evaluation Scheme may be used by health officials to eradicate the breeding sites in large water containers.  Blood donations and transfusion activities should be carried under utmost care and precautionary measures.  It is recommended to abstain from sexual activities if one suffers from ZIKV infection.  Pregnant women should take very proper care and preventive measures to protect themselves from mosquito bites and also should regularly be in contact with healthcare professionals.  It is recommended to avoid travel to ZIKV hit areas.

World Health Organization has declared the Zika outbreak a global health emergency and has left no stone unturned to combat its spread. It has activated its Emergency Operations Management System – Strategic Operation and Joint Operations Plan, to provide support to the afflicted countries and further figure out an effective plan to control its outbreak and spread to other areas. The details can be read in the report: /1/ZikaResponseFramework_JanJun16_en g.pdf?ua= /1/ZikaResponseFramework_JanJun16_en g.pdf?ua=1

1. Virology Blog, about viruses and viral disease World Health Organization, Media centre Centers for Disease Control and Prevention Oehler E, Watrin L, Larre P, Leparc-Goffart I, Lastère S, Valour F, Baudouin L, Mallet HP, Musso D, Ghawche F. Zika virus infection complicated by Guillain-Barré syndrome – case report, French Polynesia, December Euro Surveill. 2014;19(9):pii= Available online: aspx?ArticleId=20720