Rotavirus: Not for the Weak of Stomach

The rotavirus, belonging to the Reoviridae family, consists of seven major groups - three that are known to affect human beings (referred to as groups A, B, and C). Group A is the most common and also the most widespread - crossing nations and oceans. The rotavirus causes vomiting and diarrhea, and has killed approximately 600,000 children every year in developing countries.

Rotaviruses manipulate the gastrointestinal epithelial cells. The triple protein coat allows them to be resistant to the pH of the stomach and its acids, as well as the digestive enzymes present in that part of the body. As the rotavirus infects the human, it continues to replicate over and over again to produce more of itself.

This virus causes acute gastroenteritis, which involves vomiting and diarrhea along with an inflammatory infection of the colon, or a noninflammatory infection the upper small bowel. Other names associated with this disease are "infantile diarrhea", "winter diarrhea", "stomach flu", "acute nonbacterial infectious gastroenteritis", and "acute viral gastroenteritis".

The infection lasts up to 10 days and is self-limiting, from mild to severe. It is characterized by vomiting, watery diarrhea, and fever. A person with the virus can contaminate various number of things because they excrete large amounts of the virus through bodily functions. The virus can be acquired through contaminated hands, objects, or utensils.

The incubation period of the virus is between 1-3 days. Vomiting is normally the first symptom, with diarrhea starting afterward for approximately 4-8 days. Recovery is complete unless the infected person does not replace their fluids and electrolytes. If they do not do this, it can result in death due to the loss of both through the severe diarrhea. Mortality of children in the United States is relatively low, coming in at about 100 cases per year. But worldwide, it is a much bigger problem.

All humans are susceptible to the rotavirus, but children 6 months to 2 years of age, premature infants, the elderly, and those with weak immune systems are more prone than others. Group A is the most common and spread worldwide. It includes approximately 20% of all rotavirus cases and half of the cases that require hospital stays. In the United States, there are over 3 million cases of rotavirus every year, and almost every child has been infected by the age of 5. It mostly occurs in the winter in areas with temperate weather but can occur throughout the year in areas with tropic weather.

Group B is the adult version of the rotavirus, and is commonly called adult diarrhea rotavirus (ADRV). It has caused epidemics in China, affecting thousands of people of all ages. The last group known to infect humans, Group C, has been more rare and sporadic in many different countries. The first outbreaks of Group C were reported in Japan and England. There are approximately 120 million rotavirus infections every year.

Transmission of the rotavirus is most commonly done through the fecal-oral route. It is spread person-to-person through contaminated hands in close communities such as day cares, geriatric wards, pediatric wards, and family homes. Since rotaviruses are very stable in the environment, they can even be spread by people who are infected to foods that require little or no cooking such as hors d'oeuvres, salads, and fruits.

In 2006, two vaccines were placed on the market that are both safe and effective for children. They are Rotarix by GlaxoSmithKline and RotaTeq by Merck. Both are taken orally. In February 2006, RotaTeq was approved by the United States Food and Drug Administration for use in the U.S. Merck set the price of the vaccine at $187.50 for the three-dose regimen, which is higher than most standard childhood vaccines. This price will prevent its use in poor countries even if there are allowable discounts. However, Merck is working to provide the vaccine for developing countries through various partners including the Rotavirus Vaccine Project, PATH, and other government (and non-government) organizations.

Rotashield, an earlier vaccine developed by Wyeth-Ayerst, was taken off the market in the last 1990s due to its connection with bowel obstruction in infants within 1-2 weeks after the vaccine was administered.