Emergence of Zika Fever Poses a Public Health Concern
Zika fever also known as Zika virus disease or Zika is an infectious disease of global public health concern. The etiologic was isolated for the first time in 1947 from a captive sentinel rhesus monkey in Uganda, Africa. Later, the virus was recovered from the mosquito, Ades africanus caught from the Zika forest of Uganda. The disease gets its name from the Zika forest in Uganda. The first massive outbreak of Zika fever was recorded from the Island of Yap in 2007. Since then, outbreaks of Zika fever have occurred in several regions of the world, such as Africa, Americas, Asia, and Pacific. Imported cases are reported from many European nations. Globally, the exact data on the prevalence, incidence and geographic distribution of Zika infection is not available.
Disease is caused by Zika virus, which belongs to genus Flavivirus and family Flaviviridae. The virus is a non-segmented, enveloped, single stranded, positive sense RNA genome. Zika virus can be killed by potassium permanganate (0.5%), and temperatures above 60°C but is not inactivated by 10% ethanol.
Zika fever is primarily transmitted through the bite of mosquitoes of the genus Aedes. Rarely, infection can also occur by sexual contact and blood transfusion. Zika virus has been isolated from semen samples. During the outbreak of Zika virus in French Polynesia, 2 mothers and their newborns were found to have Zika virus infection within 4 days of birth. The infants appear to have acquired the infection by transplacental transmission or during delivery.
In majority of people, no symptoms are observed. Clinical manifestations in affected persons include fever, headache, skin rashes, pain in muscles, and joints, weakness, and conjunctivitis. In pregnant women, it can cause miscarriage, preterm birth besides microcephaly. Duration of illness lasts for less than a week. Mother-to-child transmission during pregnancy can cause microcephaly and other brain malformations in some babies. Infections in adults are linked to Guillain–Barré syndrome (GBS). Rarely, death can occur from sudden subarachnoid hemorrhage caused by a ruptured aneurysm.
Due to lack of characteristic clinical findings, laboratory help becomes imperative to confirm an unequivocal diagnosis of disease by employing virological (isolation of virus), immunological (enzyme linked sorbent assay), and molecular (reverse transcriptase polymerase chain reaction) techniques. Disease should be differentiated from Chikungunya fever, dengue fever, leptospirosis, malaria, Mayaro fever, measles, Rocky Mountain spotted fever, Ross River, Rubella, Sindbis fever, West Nile fever, and Yellow fever.
The disease is usually mild and requires no specific therapy. Presently, no specific antiviral drug is available for treatment. However, treatment with acetaminophen may help to relieve the symptoms. The patient is seldom admitted to the hospital.
Currently, no vaccine is available to control the disease. Therefore, certain measures, such as spraying insecticide or fumigation to kill mosquitoes, application of repellents on exposed parts, wearing of long-sleeved shirts and long trousers, treatment of clothes with permethrin, covering cribs, strollers, or baby carriers with a mosquito net, use of wire mesh on doors and windows, sleeping under a mosquito net, avoiding stagnation of water, environmental sanitation, testing of blood for Zika virus before transfusion, and avoiding visit to Zika virus affected regions are suggested to prevent Zika fever. It is pertinent to mention that area within 3-km periphery should be considered as a Zika containment area.
In India, a long-term surveillance network is required in order to estimate the impact of Zika virus on public health. It is advised that pregnant women should not travel to Zika affected areas. Further work on the reservoir, pathogenesis, molecular epidemiology, and chemotherapy should be conducted. Scientists should attempt to develop a safe, potent and low cost vaccine, which can be easily affordable by poor resource countries to immunize the susceptible population.