Zika virus Disease

"Zika virus Disease"

Since the first case of Zika virus has been detected in Pune district yesterday,we should on our guards !

Zika virus is a member of the virus family Flaviviridae.It is spread by daytime-active Aedes mosquitoes, such as A. aegypti and A. albopictus.Its name comes from the Ziika Forest of Uganda, where the virus was first isolated in 1947.Zika virus shares a genus with the dengue, yellow fever, Japanese encephalitis, and West Nile viruses.Since the 1950s, it has been known to occur within a narrow equatorial belt from Africa to Asia. From 2007 to 2016, the virus spread eastward, across the Pacific Ocean to the Americas, leading to the 2015–2016 Zika virus epidemic.

Zika fever (also known as Zika virus disease) is an illness caused by Zika virus.Most cases have no symptoms, but when present they are usually mild and can resemble dengue fever.Symptoms may include fever, red eyes, joint pain, headache, and a maculopapular rash.Symptoms generally last less than seven days.It has not caused any reported deaths during the initial infection. Infection during pregnancy causes microcephaly and other brain malformations in some babies. Infection in adults has been linked to Guillain–Barré syndrome (GBS) and Zika virus has been shown to infect human Schwann cells.

Diagnosis is by testing the blood, urine, or saliva for the presence of Zika virus RNA when the person is sick.In 2019, an improved diagnostic test, based on research from Washington University in St. Louis, that detects Zika infection in serum was granted market authorization by the FDA.

The infection, known as Zika fever or Zika virus disease, often causes no or only mild symptoms, similar to a very mild form of dengue fever.While there is no specific treatment, paracetamol (acetaminophen) and rest may help with the symptoms.As of April 2019, no vaccines have been approved for clinical use, however a number of vaccines are currently in clinical trials.

Zika can spread from a pregnant woman to her baby. This can result in microcephaly, severe brain malformations, and other birth defects.Zika infections in adults may result rarely in Guillain–Barré syndrome.

A longitudinal study shows that 6 hours after cells are infected with Zika virus, the vacuoles and mitochondria in the cells begin to swell. This swelling becomes so severe, it results in cell death, also known as paraptosis. This form of programmed cell death requires gene expression. IFITM3 is a trans-membrane protein in a cell that is able to protect it from viral infection by blocking virus attachment. Cells are most susceptible to Zika infection when levels of IFITM3 are low. Once the cell has been infected, the virus restructures the endoplasmic reticulum, forming the large vacuoles, resulting in cell death.

The vertebrate hosts of the virus were primarily monkeys in a so-called enzootic mosquito-monkey-mosquito cycle, with only occasional transmission to humans like the yellow fever virus and the dengue fever virus (both flaviviruses), and the chikungunya virus (a togavirus).Though the reason for the pandemic is unknown, dengue, a related arbovirus that infects the same species of mosquito vectors, is known in particular to be intensified by urbanization and globalization.Zika is primarily spread by Aedes aegypti mosquitoes, and can also be transmitted through sexual contact or blood transfusions.

Since Zika is primarily spread by the female Aedes aegypti mosquito, which is active mostly in the daytime, due deligence must be shown in the flood affected areas.The mosquitos must feed on blood to lay eggs. The virus has also been isolated from a number of arboreal mosquito species in the genus Aedes, such as A. africanus, A. apicoargenteus, A. furcifer, A. hensilli, A. luteocephalus, and A. vittatus, with an extrinsic incubation period in mosquitoes around 10 days.

The true extent of the vectors is still unknown. Zika has been detected in many more species of Aedes, along with Anopheles coustani, Mansonia uniformis, and Culex perfuscus, although this alone does not incriminate them as vectors.

To detect the presence of the virus usually requires genetic material to be analysed in a lab using the technique RT-PCR. A much cheaper and faster method involves shining a light at the head and thorax of the mosquito, and detecting chemical compounds characteristic of the virus using near-infrared spectroscopy.

Research into its ecological niche suggests that Zika may be influenced to a greater degree by changes in precipitation and temperature than dengue, making it more likely to be confined to tropical areas. However, rising global temperatures would allow for the disease vector to expand their range further north, allowing Zika to follow.

Zika can be transmitted from men and women to their sexual partners; most known cases involve transmission from symptomatic men to women. ZIKV can persist in semen for several months, with viral RNA detected up to one year. The virus replicates in the human testis, where it infects several cell types including testicular macrophages, peritubular cells and germ cells, the spermatozoa precursors.Semen parameters can be altered in patients for several weeks post-symptoms onset, and spermatozoa can be infectious.

Zika virus can spread by vertical (or "mother-to-child") transmission, during pregnancy or at delivery.An infection during pregnancy has been linked to changes in neuronal development of the unborn child.Severe progressions of infection have been linked to the development of microcephaly in the unborn child, while mild infections potentially can lead to neurocognitive disorders in adulthood. Congenital brain abnormalities other than microcephaly have also been reported after a Zika outbreak.Maternal immunity to dengue virus may enhance fetal infection with Zika, worsen the microcephaly phenotype and/or enhance damage during pregnancy, but it is unknown whether this occurs in humans.

Two cases of Zika transmission through blood transfusions have been reported globally, both from Brazil,after which the US Food and Drug Administration (FDA) recommended screening blood donors and deferring high-risk donors for 4 weeks.A potential risk had been suspected based on a blood-donor screening study during the French Polynesian Zika outbreak, in which 2.8% (42) of donors from November 2013 and February 2014 tested positive for Zika RNA and were all asymptomatic at the time of blood donation. Eleven of the positive donors reported symptoms of Zika fever after their donation, but only three of 34 samples grew in culture.

Prevention involves decreasing mosquito bites in areas where the disease occurs, and proper use of condoms. Efforts to prevent bites include the use of DEET or picaridin - based insect repellent, covering much of the body with clothing, mosquito nets, and getting rid of standing water where mosquitoes reproduce.There is no vaccine.Health officials recommended that women in areas affected by the 2015–2016 Zika outbreak consider putting off pregnancy and that pregnant women not travel to these areas.While no specific treatment exists, paracetamol (acetaminophen) and rest may help with the symptoms.Admission to a hospital is rarely necessary.