Zika virus（ZIKV） is named after the zika Forest in Uganda, and was first isolated from the sentinel rhesus monkey in 1947. Compare to other diseases, zika virus infection symptoms are mild, but it attacks two of the most vulnerable groups – pregnant women and newborns, causing panic among people. Now the zika infections are a concern as the summer mosquito season nears. Some scientists believe that zika is going to come back with a vengeance this summer.
How ZIKV Spreads
Historically terrible viruses have two characteristics: fast transmission and strong lethality. First, at the speed of transmission, the zika virus is a typical arbovirus, which is mainly transmitted by mosquitoes of the genus Aedes. Aedes can be infected once it gets touch with infection sources, then zika viruses in the Aedes mosquitoes are infectious after getting mosquito saliva in 5-10 days. Then infected mosquitoes, the virus carriers, can spread the virus to other people through bites.
Actually most of the Flaviviruses are not able to reproduce enough quantities to transmit to the next potential carrier after passing on to the host, so the entire spread process ends, and the infected host is called dead-end-host. But the zika virus’ vitality is very powerful, it can stay in the host body to copy a sufficient number, so that the host can also spread the virus to other mosquitoes, establishing an infinite “host – mosquito – the next host – mosquito” mode of transmission.
Less than 20% of those infected with zika virus will have mild symptoms, such as fever, joint pain, muscle pain, headache, but most of the them have no symptoms, and they do not even know that they’ve been infected. Generally symptoms will last for two days to a week and it will heal by themselves. People usually don’t get sick enough to go to the hospital, and they very rarely die of zika virus. Do you think it sounds like nothing terrible? Why doed the WHO set the zika as a “high alarm”?
In fact, zika virus did not get the attention at first, although in 2007 zika in the Pacific Yap Island were strongly contagious, people still think it is more mild than dengue. Scientific discovery finds infected woman’s newborns are susceptible to have microcephaly — babies born with a smaller-than-normal head and underdeveloped brains, which may lead to nerve and mental defects, as well as visual and auditory problems.
In 2006, the incidence of microcephaly among neonatal have increased by 20 times in Brazil, where the epidemic was most severe. So the terrible thing about the zika virus is that many zika carriers do not know that they are being infected and continue to spread the virus, and cause devastating birth defects.
In the 2013-2014, after Polynesia occurred the zika virus and dengue fever mixed epidemic, the local found Guillain-Barré syndrome increased abnormally, which was also observed during the spread of zika virus in Brazilian.
Latest Research on ZIKV
So far there is no vaccines for zika virus, and the best method is to prevent mosquito bites. According to the new research, the zika virus may be able to pass through the placenta by binding to certain sugars on the surface of cells, called chondroitin sulfate. Scientists now are looking for a way to block the interactions between zika and placental glycoprotein, aiming to prevent the virus from causing birth defects.