Zika spread: Serious concern

There is no case of Zika reported from Nepal yet. However, the possibility of viral circulation in Nepal cannot be ruled out. In India, there are reports of seropositive cases who demonstrate anti-Zika antibodies in their serum sample

Most viruses, unlike bacteria, are merciless as they are obligate parasites. The pathogenicity of viruses, however, falls within a wide spectrum: benign to severe. In the world of infections, a group of viruses has recently been dubbed to have serious public health threat, which otherwise was known to have only milder effects. Zika virus, a member of family Flaviridae, has recently shown up causing outbreaks in South America with the disease Zika. The infection by this virus has been said to have links with a rare neurologic disorder called microcephaly, congenital malformation, in which normal growth of head as well as brain development of the fetus is impeded.

Zika virus is a cousin of Dengue Virus as both of them fall in same family. Besides these two, Japanese Encephalitis, West Nile and Yellow Fever viruses fall in the same category. There is distinct similarity in the way of transmission of all viruses of this category. Zika as well as Dengue viruses are transmitted by the bite of infected female mosquito of genus Aedes. However, West Nile virus is explicitly transmitted by the bite of blood sucking Culex mosquitoes. Although it is rare for Dengue, an infected mother can also transmit Zika during pregnancy or labor. Zika viruses are often misdiagnosed as Dengue infection because of similar yet milder spectrum of clinical symptoms both manifest. Like other flaviviruses, Zika virus consists of RNA as a hereditary material enclosed inside its icosahedral capsid.

Scientists had not expected Zika to impact public health on such a great scale as it was thought to be confined within the narrow equatorial belt across Africa. After the virus was accidentally discovered in 1947 in Uganda, milder enzoonic infections involving humans sporadically were found to be associated with Zika. These viruses, however, have gone beyond this region showing its pandemic potentiality by circulating throughout the globe now. According to Centers for Disease Control and Prevention (CDC), there have been several reported outbreaks so far in Africa, Southeast Asia, the Pacific Islands and the Americas. Recently Brazil, in South America, saw an unusual surge of Zika virus cases within the last two years. The virus has been found not only in the Americas but is circulating throughout Africa, in Mekong territories and possibly in the Indian subcontinent where antibodies against Zika have been reported in the serum of the diseased cases. It was believed that the clinical impacts of Zika Virus are milder and were not taken seriously before. It was found to cause milder fever, rashes, conjunctivitis, muscles and joint pain, yet not as prominent as those caused by the Dengue Virus. Only one in four infected people is said to come up with symptoms which generally fade away after 2 to 7 days.

Recently, Brazil observed a tenfold increase in the number of babies born with microcephaly and researchers suspect its link with the soaring number of cases with Zika virus in later years after they hosted the World Cup Football in 2014. Brazilian Ministry of Health suspects more than 3,500 cases acquired Zika within the last three months. Among these, more than 225 are confirmed of having this virus. Public health experts in Brazil claim that they have enough evidences to establish a causal relationship between microcephaly and Zika virus. They have found Zika virus particles in the amnoiotic fluid in pregnant woman carrying babies manifested with microcepahly. Scientists at CDC and Universidade Federal do Rio Grande do Norte (UFRN) investigated four cases with Bad Obstetric History. They detected Zika in the brains of two babies, who died within the first 24 hours of their life, with microcepaly. They also investigated two cases of miscarriage that were found positive for Zika virus in immune histo chemistry tests at a laboratory. In all four cases, mothers were presented with rashes and fever during pregnancy. However additional evidences are required for the confirmation of causal relationship.

World Health Organization (WHO) / Pan America Health Organization (PAHO) recommend public health authorities perform prompt surveillance of the cases that manifest neurologic syndromes in all age groups. Travel guidelines for pregnant women and those who wish to be pregnant warn them to avoid areas where the virus is circulating.

There is no case of Zika reported from Nepal yet. However, the possibility of viral circulation in Nepal cannot be ruled out. In India, there are reports of seropositive cases who demonstrate anti-Zika antibodies in their serum sample. Therefore, it is imperative for our public health authorities to facilitate researches for assessing any evidence of Zika in Nepal.

Since the virus is transmitted through the bite of Aedes mosquitoes, the wisest idea is to avoid their bites. Aedes bites outdoor during the daytime unlike those mosquitoes transmitting malaria or elephantiasis. Vector control is another effective measure to check viral transmission. Aedes vector breeds in a pool of clean water accumulated in discarded tyres, containers, flower vases, discarded cups etc. Removal of potential breeding habitats significantly reduces the occurrence of Aedes vector in the environment ultimately reducing viral transmission and incidence of infection.

Kafle is a Microbiology graduate