Zika virus (ZIKV)is a single stranded RNA virus belonging to the
Flaviviridae family, that shows similarity to other Flaviviruses (West Nile,
Dengue, Yellow Fever and Japanese Encephalitis viruses). First identified in
Africa, ZIKV has since been observed in other countries notably the Americas. In
2015, the world was gripped with reports from Brazil of Zika virus outbreak. To
date, more than 86 countries have reported cases of Zika infection.
Primarily transmitted by the
infected mosquito vector Aedes aegyptii, ZIKV can also be spread by Aedes
albopictus. Transmission additionally occurs via transplacental, perinatal,
sexual, laboratory-acquired, and transfusion routes. Majority of the
infections (>80%) are asymptomatic or cause mild illness, with a very small
proportion resulting in severe acute illness. The ZIKV outbreak in Brazilian
regions has been linked to increase in congenital microcephaly (serious birth
defect of the brain in which a baby has an abnormally small head and associated with incomplete brain development)
and other foetal development problems such as defects with eyes, ears, and
impaired growth. Zika virus can also cause post-infective neurological
syndromes notably the Guillain-Barré syndrome, an autoimmune disorder, in which
nerve cells are damaged leading to
muscle weakness and sometimes to partial or complete paralysis.
Although the Zika virus pandemic
has diminished, the virus makes repeated comebacks as demonstrated by recent
outbreaks in Asia and Africa. This raises the question as to how much we have progressed in our understanding of
the disease, and in the diagnosis and treatment of the disease, since the last outbreak.
While tests exist for the
screening of Zika virus infection, serodiagnosis is problematical because of false
positives due to cross-reactivity in patients previously infected with
other Flaviviruses. Now, researchers at ICB- USP (University Institute of
Biomedical Sciences, Brazil) have developed a new test. This test reportedly
detects Zika infection with greater accuracy and helps distinguish it from
Dengue infection. Time will tell, how this test will fare in clinical setting, once it is launched.
Apart from the limitations in accurate diagnosis of Zika virus, hurdles exist in treatment of Zika patients.The management of the disease is
difficult as interest as there are no drugs or vaccines commercially available
against Zika virus. Current treatment is aimed at relieving symptoms with rest,
fluids, and medications mainly acetaminophen, to relieve joint pain and fever. Recent
studies from researchers in the US and Spain show that the polyanionic aromatic
compound Aurintricarboxylic acid, a broad-spectrum antimicrobial and antiviral
agent could be effective against Zika
virus. The studies were conducted in cell culture experiments and therefore will require
clinical validation.
Several vaccines that will protect against Zika infection are in various stages of clinical testing. National Institute for Allergy and Infectious Disease (NIAD) is developing several vaccines, and results from some trials are eagerly anticipated later this year.
Several vaccines that will protect against Zika infection are in various stages of clinical testing. National Institute for Allergy and Infectious Disease (NIAD) is developing several vaccines, and results from some trials are eagerly anticipated later this year.
References:-
1. Basarab M, Bowman C, and Aarons EJ. Zika virus. BMJ 2016;
352: i1049
2. WHO Fact Sheet, Zika Virus.https://www.who.int/news-room/fact-sheets/detail/zika-virus
3. Revised Recommendations for Reducing the Risk of Zika
Virus Transmission by Blood and Blood Component. U.S. Department of Health and
Human Services, Food and Drug Administration, Center for Biologics Evaluation
and Research,August 2016
4. https://www.who.int/emergencies/diseases/zika/india-november-2018/en/
5. https://www.cdc.gov/zika/laboratories/types-of-tests.html
6. USP Develops Test that Identifies Zika Virus More
Accurately,FOLHA DE S. Paolo, https://www1.folha.uol.com.br/internacional/en/scienceandhealth/2019/10/usp-develops-test-that-identifies-zika-virus-more-accurately.shtml
7. Park J-G et al, Front
Microbiol. 2019; 10: 718.
8.
https://www.niaid.nih.gov/diseases-conditions/zika-vaccines