Non-pathogenic viruses

West Nile Virus WNV has been detected in at least 48 species of mosquitoes, over species of birds, at least 2 species of reptiles, and more than 25 mammalian species, including horses and humans.

Birds are the natural host and reservoir of WNV. Although other animals are susceptible to WNV infection, only birds develop a high enough virus load to transmit the infection to an uninfected Some avian influenza, or bird flu, viruses that are able to enter North America from other continents through migrating birds can be deadly to poultry Due to the global threat to health and human safety posed by avian influenza monitoring has been conducted in the United States to determine the Ducks in North America can be carriers of avian influenza viruses similar to those found in a outbreak in Indiana that led to the losses of Geological Survey released additional evidence that western Alaska remains a hot spot for avian influenza to enter North The avian flu virus that caused widespread harbor seal deaths in can easily spread to and infect other mammals and potentially humans.

The North Atlantic region is a newly discovered important pathway for avian influenza to move between Europe and North America, according to a U. Science Explorer. Mission Areas. Unified Interior Regions. Science Centers. Frequently Asked Questions. Educational Resources. Multimedia Gallery. Web Tools. Board on Geographic Names. The National Map. USGS Library. USGS Store. Park Passes. News Releases. Featured Stories. Science Snippets. Technical Announcements.

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You will be subject to the destination website's privacy policy when you follow the link. CDC is not responsible for Section compliance accessibility on other federal or private website. Individual strains of phages are tested against target bacteria, and the most effective strains are purified into a potent concentration.

These are stored as either bacteriophage stocks cocktails , which contain one or more strains of phages and can target a broad range of bacteria, or as Adapted bacteriophages, which target specific bacteria. Before treatment, a swab is collected from the infected area of the patient, cultured in the lab to identify the bacterial strain, and tested against the therapeutic phage stocks.

Treatment can be safely administered orally, applied directly onto wounds or bacterial lesions, or even spread onto infected surfaces. Clinical trials for intravenous administration of phages are ongoing. Viral infections at a young age are important to ensure the proper development of our immune systems. In addition, the immune system is continuously stimulated by systemic viruses at low levels sufficient to develop resistance to other infections. For example, latent non-symptomatic herpes viruses can help human natural killer cells a specific type of white blood cell identify cancer cells and cells infected by other pathogenic viruses.

They arm the natural killer cells with antigens a foreign substance that can cause an immune response in the body that will enable them to identify tumour cells. This is both a survival tactic by the viruses to last longer within their host, and to get rid of competitive viruses to prevent them from damaging the host. In the future, modified versions of viruses like these could potentially be used to target cancer cells. The virus slows disease progression by blocking the host receptors required for viral entry into the cell, and promotes the release of virus-detecting interferons and cytokines proteins produced by white blood cells that activate inflammation and removal of infected cells or pathogens.