But occasionally, when a new flu strain emerges, a pandemic results in a faster spread of disease and, often, higher mortality rates. Dengue virus first appeared in the s in the Philippines and Thailand and has since spread throughout the tropical and subtropical regions of the globe, according to Clinical Microbiology Reviews.
A vaccine for Dengue was approved in by the U. Food and Drug Administration for use in children years old living in areas where dengue is common and with a confirmed history of virus infection, according to the CDC. In some countries, an approved vaccine is available for those years old, but again, recipients must have contracted a confirmed case of dengue in the past.
Those who have not caught the virus before could be put at risk of developing severe dengue if given the vaccine. Two vaccines are now available to protect children from rotavirus, the leading cause of severe diarrheal illness among babies and young children. The virus can spread rapidly, through what researchers call the fecal-oral route meaning that small particles of feces end up being consumed.
Although children in the developed world rarely die from rotavirus infection , the disease is a killer in the developing world, where rehydration treatments are not widely available. The WHO estimates that worldwide, there are more than 25 million outpatient visits and two million hospitalizations each year due to rotavirus infections.
Countries that have introduced the vaccine have reported sharp declines in rotavirus hospitalizations and deaths. The virus likely emerged in bats initially, then hopped into nocturnal mammals called civets before finally infecting humans, according to the Journal of Virology.
After triggering an outbreak in China, SARS spread to 26 countries around the world, infecting more than people and killing more than over the course of several months, according to History. The disease causes fever, chills and body aches, and often progresses to pneumonia, a severe condition in which the lungs become inflamed and fill with pus. SARS has an estimated mortality rate of 9.
The virus may have originated in bats and passed through an intermediate animal before infecting people, according to Nature. The initial outbreak prompted an extensive quarantine of Wuhan and nearby cities, restrictions on travel to and from affected countries and a worldwide effort to develop diagnostics, treatments and vaccines.
Since its appearance, the virus has caused over five million deaths worldwide, according to Reuters. Common symptoms include fever, cough, loss of taste or smell and shortness of breath and more serious symptoms include breathing difficulties, chest pain and loss of mobility. On Aug. In December , this vaccine became the first to be approved after a large clinical trial, according to Nature. According to WHO , the disease infected camels before passing into humans and can trigger a fever, coughing and shortness of breath in infected people.
There is no vaccine available to prevent this disease, according to the NHS. The best way to reduce the chances of infection is to wash hands regularly, avoid contact with camels and not consume products containing raw animal milk. Live Science. See all comments Don't said:. Meh said:. Comment on rabies fatality rate. Likewise, the AIDS epidemic—which has afflicted 78 million people and killed half of them since it was recognized in —is no longer a death sentence because a cocktail of drugs can now contain the HIV retrovirus from victims with the disease.
The plus species of rhinovirus are the usual cause of the common cold. For children under the age of five, rotavirus is the leading cause of severe diarrhea. Many children in the United States are infected at least once. The disease is untreatable, but there is a vaccine, and rehydration therapy is needed as the disease runs its course. Worldwide, however, rotavirus accounts for ,, or 5 percent, of childhood deaths. In sub-Saharan Africa, Pakistan, and Bangladesh—where there is lack of access to clean drinking water for rehydration therapy and to health care facilities to administer the therapy—the death rate is to 1, deaths per , So, depending on your resources and where you raise your children, rotavirus is either bad or truly ugly.
The mumps virus protein called small hydrophobic protein turquoise can be seen here in the endoplasmic reticulum of a cultured cell. This is a region of the cell that processes proteins.
This particular protein is possibly involved in determining how effectively the virus can infect people. Good viruses have never received the recognition they deserve. While bacteria account for the bulk of microorganisms in our microbiome, there is a virus component, or virome, to our microbiome. The results of a recent study suggest that some of these viruses are interacting with our body to keep us healthy. For example, phages, which cannot infect our cells, can interact with our mucus layers and provide a barrier from bacterial infection.
These phages are oriented in such a way that their tail fibers interact with bacteria and prevent them from getting to the mucus layer and transiting through to our cells. The phages provide a line of defense against the bacteria, because the phage will attach, replicate, kill the bacteria, and exit the cell. As an integral part of our body, versus being on or in our body, 8—18 percent of our DNA—segments of genetic material called transposons—are believed derived, in some cases, from viruses.
During pregnancy in viviparous mammals—which are all mammals except egg-laying monotremes—ERVs are activated and proliferate during the implantation of the embryo.
They act as immunodepressors. Also, viral fusion proteins apparently cause the formation of the syncytium—the outer cell layer of the placenta—in order to limit the exchange of migratory cells between the developing embryo and the body of the mother something an epithelium will not do sufficiently, as certain blood cells are specialized to be able to insert themselves between adjacent epithelial cells. The immunodepressive action was the initial normal behavior of the virus; similar to HIV, the fusion proteins were a way to spread the infection to other cells by simply merging them with the infected one HIV does this too.
It is believed that the ancestors of modern viviparous mammals evolved after an infection by this virus, enabling the fetus to survive the immune system of the mother. However, there is an ugly side to human relationships with the ERVs in our chromosomes: some ERVs may be contributing agents for such diseases as cancers, multiple sclerosis, and diabetes, although these possibilities are not yet confirmed and constitute active areas of ongoing research.
Viruses play a vital role controlling the balance of ecosystems. Half the oxygen in the atmosphere is produced by cyanobacteria in the ocean. Cyanophages, which live alongside cyanobacteria and outnumber them by about ten to one, prey on the bacteria, killing an estimated 20 percent each day. What are they doing with photosynthesis genes? It starts to make sense when we think about the virus life cycle and the necessity to keep cyanobacteria cells going and churning through their metabolism, while viruses are undergoing replication—a process that ultimately destroys the cyanobacteria.
Bringing in photosynthesis genes to cyanobacteria cells is like adding fuel to the process. A net result: an estimated 5 percent of the oxygen in the atmosphere is indirectly produced by cyanophages. Viruses also provide a variety of services for plants.
A few plants grow in the hot soils surrounding the geysers and the "Artists' Paintpots" of Yellowstone National Park. One such plant, which is a type of tropical panic grass, is a symbiosis that includes a fungus that colonizes the plant, and a virus that infects that fungus. All three members of this symbiosis are necessary for survival in soils simmering at more than degrees Fahrenheit.
In the laboratory, Roossinck has created symbioses between the same virus-infected fungus and other plants. This has enabled every plant her group has tested to survive at these elevated soil temperatures, including tomato, she says, noting that she has pushed the soil temperature to degrees without killing the plant. Investigators have also found that certain viruses can render some plants drought tolerant, and at least one example of virally-conferred cold tolerance has been discovered-- discoveries that could become useful for expanding the ranges of crops.
Plants are often infected with "persistent viruses" that are passed down from generation to generation, perhaps over thousands of years, with viruses that are transmitted to nearly percent of their plant progeny, but that have never been shown to be transmitted from one plant to another.
Other beneficial viruses are the ancient retroviruses that long ago made a permanent home in the genome, or that left genes therein, said Roossinck. I was always a little disturbed at the bad rap they get, so it was very exciting for me to find good ones. Materials provided by American Society for Microbiology.
Note: Content may be edited for style and length. Science News. Journal Reference : Marilyn J.
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