Date: Thu 26 Sep 2019, 12:00 AM
Source: Daily Sun [edited]
A new mosquito-borne virus, West Nile Virus (WNV), has been found in Bangladesh. However, detailed information about the virus has not been available yet as the government's concerned department didn't investigate to know its origin.
According to the experts, West Nile is a potentially life-threatening viral infection which can pass to animals and humans if they are bitten by an infected mosquito.
WNV is a virus of the _Flaviviridae_ family, which includes the viruses responsible for Japanese encephalitis and dengue fever. It mainly affects birds, but it can also infect mammals and reptiles. Between 70-80% of people have no symptoms. Up to 1% of those who become ill have serious and potentially fatal complications, they added.
"We have asked the Institute of Epidemiology Disease Control and Research (IEDCR) to investigate the West Nile virus," said Dr. Sanya Tahmina Jhora, Director of the Disease Control unit of Directorate General of Health Services (DGHS) on [Wed 25 Sep 2019].
Asked about the West Nile virus, Prof. Dr Meerjady Sabrina Flora, Director of Institute of Epidemiology of the IEDCR, said: "A report about the West Nile virus has come to us. A study of the ICDDR,B (International Centre for Diarrhoeal Disease Research, Bangladesh) has mentioned the detection the virus in Bangladesh. Our team will go to the spot and carry out investigation about the West Nile virus. We can give details about it after the investigation," she added.
The DGHS sources said the ICDDR,B detected the West Nile virus infected patient in an area near Dhaka city and informed the concerned authorities of the government to this end. However, talking to Daily Sun, the ICDDR,B communication department refused to comment.
According to the Centers for Disease Control and Prevention of the United States (US), West Nile virus (WNV) is the leading cause of mosquito-borne disease in the continental United States.
It is most commonly spread to people by the bite of an infected mosquito. Cases of WNV occur during mosquito season, which starts in the summer and continues through fall. There are no vaccines to prevent or medications to treat WNV in people," it said.
The report also said "most people infected with WNV do not feel sick, but about 1 in 5 people who are infected develop a fever and other symptoms. About 1 out of 150 infected people develop a serious, sometimes fatal, illness. You can reduce your risk of WNV by using insect repellent and wearing long-sleeved shirts and long pants to prevent mosquito bites."
The World Health Organization (WHO) said the West Nile virus can cause a fatal neurological disease in humans, while approximately 80% of people who are infected will not show any symptoms. "West Nile virus is mainly transmitted to people through the bites of infected mosquitoes. The virus can cause severe disease and death in horses. Vaccines are available for use in horses but not yet available for people. Birds are the natural hosts of West Nile virus," it said.
The WHO statement said WNV can cause neurological disease and death in people. "WNV is a member of the _flavivirus_ genus and belongs to the Japanese encephalitis antigenic complex of the family _Flaviviridae_. WNV is maintained in nature in a cycle involving transmission between birds and mosquitoes. Humans, horses and other mammals can be infected," it added. The WHO statement said human infection is most often the result of bites from infected mosquitoes. Mosquitoes become infected when they feed on infected birds, which circulate the virus in their blood for a few days. The virus eventually gets into the mosquito's salivary glands. During later blood meals (when mosquitoes bite), the virus may be injected into humans and animals, where it can multiply and possibly cause illness.
It said the virus may also be transmitted through contact with other infected animals, their blood, or other tissues. A very small proportion of human infections have occurred through organ transplant, blood transfusions and breast milk.
The WHO report further said infection with WNV is either asymptomatic (no symptoms) in around 80% of infected people or can lead to West Nile fever or severe West Nile disease. About 20% of people who become infected with WNV will develop West Nile fever. The report added that symptoms include fever, headache, tiredness, and body aches, nausea, vomiting, occasionally with a skin rash (on the trunk of the body) and swollen lymph glands. The symptoms of severe disease (also called neuroinvasive disease, such as West Nile encephalitis or meningitis or West Nile poliomyelitis) include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis.
It is estimated that approximately 1 in 150 people infected with the West Nile virus will develop a more severe form of the disease. Serious illness can occur in people of any age; however, people over the age of 50 and some immunocompromised persons (for example, transplant patients) are at the highest risk for getting severely ill when infected with WNV. The incubation period is usually 3 to 14 days.
The WHO further said that treatment is supportive for patients with neuro-invasive West Nile virus disease, often involving hospitalization, intravenous fluids, respiratory support, and prevention of secondary infections. No vaccine is available for humans. [Byline: Mohammad Al Amin]
[The news report above indicates the detection of West Nile virus (WNV) by the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) in a patient near Dhaka city, the Capital in Bangladesh. This is the 1st report of WNV from Bangladesh affecting humans. A further investigation from the health authority concerned in the country seems underway to obtain more information about the reported finding.
Earlier, Islam et al have reported WNV antibody prevalence of approx. 5.4 percent in resident and migratory wild birds in 2015 [Islam, Ariful & Rahman, Mohammad & Paul, Suman & Hannan, M. A. & Hossain, Mohammad Elius & Rahman, Mohammed & Hosseini, Parviez & Dey, T. & Zeidner, N.. (2015). Seroprevalence of West Nile Virus in Wild Birds in Bangladesh].
West Nile virus (WNV) was 1st isolated in a woman in the West Nile district of Uganda in 1937. It was identified in birds (crows and columbiformes) in the Nile delta region in 1953. Before 1997, WNV was not considered pathogenic for birds, but at that time in Israel, a more virulent strain caused the death of different bird species, presenting signs of encephalitis and paralysis.
The largest WNV outbreaks occurred in Greece, Israel, Romania, Russia and the USA, with outbreak sites on major bird migratory routes. In its original range, WNV was prevalent throughout Africa, parts of Europe, Middle East, West Asia, and Australia. Since its introduction in 1999 into the USA, the virus has spread and is now widely established from Canada to Venezuela.
Human infection most often results from bites of infected mosquitoes. Mosquitoes become infected when they feed on infected birds, which circulate the virus in their blood for a few days. The virus eventually gets into the mosquito's salivary glands. During later blood meals (when mosquitoes bite), the virus may be injected into humans and animals, where it can multiply and possibly cause illness. The virus may also be transmitted through contact with other infected animals, their blood, or other tissues. Rarely, human infections have occurred through organ transplant, blood transfusions and breast milk. There is one reported case of transplacental (mother-to-child) WNV transmission (<https://www.who.int/news-room/fact-sheets/detail/west-nile-virus
About 20 percent of people who become infected with WNV will develop West Nile fever. Symptoms include fever, headache, tiredness, and body aches, nausea, vomiting, occasionally with a skin rash (on the trunk of the body) and swollen lymph nodes.
Treatment is supportive for patients with neuro-invasive West Nile virus disease, often involving hospitalization, intravenous fluids, respiratory support, and prevention of secondary infections. No vaccine is available for humans. - ProMED Mod.UBA]
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