Saturday, March 3, 2012


Summer is often the real season for infectious diseases as the bugs can thrive under optimal weather conditions available during the period. With the pathogens multiplying at a frenetic pace, they spread rapidly among the population through air, water, food and direct contact with contaminated surfaces. Added to this water scarcity gets acute during summer and hand washing becomes the first casualty. This is true for Bacteria, Virus and other disease causing vectors. Interestingly in a country like the US where winter conditions are still prevalent, a warning has been issued regarding the danger posed by Norvirus, earlier known as Norfolk Agent, and one can imagine the potency of this virus to cause havoc even under hostile conditions. Here is a take on this development.  

"There are some important reasons that lead to so many people becoming ill from Norovirus," said Martin Bucknavage, extension food safety specialist. "One is the virus's low infectious dose. It is estimated that it may take only 10 viral particles to make someone ill. Then, there is the ability of the virus to survive on dry surfaces for two weeks or more and in water for months." The virus, which often moves quickly through a school or cruise ship, can be spread in contaminated food or water, from contaminated surfaces, directly from a sick person or from the intake of aerosolized droplets of vomit. And the main symptom of a Norovirus infection is another factor in its spread -- acute-onset vomiting. "This prevents people from becoming sick in a secure location," Bucknavage said. "Rather, rapid onset can occur at a dinner table, in a meeting or on the bus. People usually become ill within 24 hours of exposure, although longer incubation periods do occur." And once someone gets sick, they can experience symptoms for 24 to 72 hours and can remain contagious for up to three days. Bucknavage says the key to preventing infection is frequent and correct hand washing -- scrubbing hands with soap and warm water. In addition, it's important for people to stay home when ill, especially when they may have been exposed to someone who has had the illness". 

Though the danger is confined to the population of the US where instances of food poisoning have been reported, its advent under tropical conditions cannot be ruled out. If Norovirus is so common in the atmosphere there could be the possibility that most of the population in these regions have already developed immunity long ago and only those with weak immunity might be exposed to the risk. But the immunity developed due to single exposure is considered temporary raising some concerns. An encouraging factor is that most foods consumed in tropical countries are invariably over-cooked causing destruction of all pathogens.Similarly chlorinated water is supposed to be free from this virus. Considering that Norovirus accounts for more than 90% of non-bacterial GI infection, it is better constant vigil is kept on incidences of infections caused by this RNA based virus.


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