Zika Virus (ZIKV)

Zika Virus (ZIKV) is an arbovirus in the Flaviviridae family, genus Flavivirus. ZIKV is primarily transmitted by mosquito bites of the Aedes species (A. aegypti and A. albopictus), the same mosquitoes that transmit the tropical viruses Dengue and Chikungunya (CHIK). ZIKV has also been found to be transmitted sexually by men, and by blood transfusion.

Common symptoms include fever, skin rash, conjunctivitis, joint pain, muscle pain, and headache. Zika fever shares many similar clinical symptoms with Dengue and CHIK fever.

Recent cases have shown that microencephaly (an abnormally small brain) in newborn babies is linked to women with a history of ZIKV infection during pregnancy. ZIKV infection is also linked to Guillain-Barre syndrome, a rare disorder where a person’s immune system damages nerve cells, causing muscle weakness and possible paralysis.

There is currently no specific medication to treat ZIKV infection or vaccine to prevent it. Treatment of specific symptoms may alleviate some discomfort. There are currently no reports of chronic Zika infection.

After the onset of symptoms, ZIKV can be detected by RT-PCR in serum during the viraemic phase for approximately one week after infection, and slightly longer in urine samples. RT-PCR detection can present a challenge as a negative result may occur towards the end of the viraemic phase. IgM and neutralizing antibodies specific to ZIKV develop approximately 5-7 days after the onset of symptoms, and last anywhere from 2-12 weeks. IgG antibodies are raised at approximately day 7 and persist longer than IgM.

Because of the similarities between ZIKV and other arboviruses such as Dengue and CHIK, antibody cross-reactivity between primary infections is very common and alternative testing methods may be needed for confirmation.