Can viruses reproduce in food

Most viruses are only 20— nanometers in diameter, whereas human egg cells, for example, are about micrometers in diameter, and the E.

Viruses are so small that they are best viewed using an electron microscope , which is how they were first visualized in the s. Viruses generally come in two forms: rods or spheres. However, bacteriophages viruses that infect bacteria have a unique shape, with a geometric head and filamentous tail fibers. No matter the shape, all viruses consist of genetic material DNA or RNA and have an outer protein shell, known as a capsid. There are two processes used by viruses to replicate: the lytic cycle and lysogenic cycle.

Some viruses reproduce using both methods, while others only use the lytic cycle. In the lytic cycle, the virus attaches to the host cell and injects its DNA. Then fully formed viruses assemble. These viruses break, or lyse, the cell and spread to other cells to continue the cycle. Like the lytic cycle, in the lysogenic cycle the virus attaches to the host cell and injects its DNA.

In humans, viruses can cause many diseases. For example, the flu is caused by the influenza virus. Typically, viruses cause an immune response in the host, and this kills the virus. However, some viruses are not successfully treated by the immune system, such as human immunodeficiency virus, or HIV.

This leads to a more chronic infection that is difficult or impossible to cure; often only the symptoms can be treated. Unlike bacterial infections, antibiotics are ineffective at treating viral infections. Viral infections are best prevented by vaccines, though antiviral drugs can treat some viral infections. Most antiviral drugs work by interfering with viral replication.

Some of these drugs stop DNA synthesis, preventing the virus from replicating. Although viruses can have devastating health consequences, they also have important technological applications. Viruses are particularly vital to gene therapy. Because some viruses incorporate their DNA into host DNA, they can be genetically modified to carry genes that would benefit the host. Some viruses can even be engineered to reproduce in cancer cells and trigger the immune system to kill those harmful cells.

The viruses most often foodborne are the hepatitis A virus and the Norwalk-like gastroenteritis viruses. Detection methods for these viruses in foods are very difficult and costly; the methods are not routine. Indicators that would rapidly and reliably suggest the presence of viral contamination of foods are still being sought.

Two of the main sources of viral infection are shellfish and food items handled by infected foodhandlers. Shellfish can be a source of foodborne viral infections because of their ability to concentrate viruses present in the water environment and they may be consumed raw or undercooked. Infected food handlers or food handlers who have come into contact with sick people can help to spread the virus via food. In some cases, an infected foodhandler may not have symptoms carrier status , like during the recovery or incubation period.

To prevent foodborne viral infection, strict observance of environmental, food, and personal hygiene is important. Dining utensils should be cleaned thoroughly before use. People, especially food handlers, should keep hands clean, e. On the other hand, high risk food like shellfish should be bought from reputable and reliable suppliers.

Susceptible populations such as children, elderly or pregnant women should avoid consuming raw shellfish or seafood. Moreover, cooking shellfish thoroughly before consumption can prevent both bacterial and viral food poisoning. Some general characteristics of viruses and bacteria related to foodborne disease are shown in the table below: Virus Bacteria Growth Require a host cell to produce more virus Can grow and multiply in suitable environment Spoilage of food No Spoilage bacteria can Formation of spore No Some can Infective dose Presumably low Can be low, but some require high dose to infect or produce toxins Cause illness by Invade human cells Invade and multiply in the body or produce toxin.

Type Gastroenteritis Hepatitis Other Pathological changes Inflammation of the stomach and small and large intestines Inflammation of the liver Replicate in human intestine but cause illness after they migrate to other organs Examples Norovirus Rotavirus Astrovirus group A to C Adenovirus type 40 or 41 Hepatitis A virus Hepatitis E virus Enteroviruses, e.