Rotavirus is one of the primary causes of gastroenteritis among children around the world and the most common cause of severe diarrhea. There are approximately 130 million cases worldwide annually and over 500,000 deaths. In the United States, about 55,000 children are hospitalized each year due to gastroenteritis caused by rotavirus.
There are eleven different strains of rotavirus, of which four are known to cause diarrhea in humans. The disease has an incubation period of up to two days, after which symptoms such as fever, stomach ache, vomiting, and diarrhea appear. The disease is usually selflimiting within eight days. However, dehydration is a severe complication and may prove fatal if untreated.
Rotavirus is very stable in the environment and while transmission usually occurs through ingestion of fecally contaminated food or water, people may also become infected following contact with contaminated surfaces, such as toys and benches. Prior infection by rotavirus may reduce the severity of subsequent infections and, due to this fact, trials of a vaccine are being conducted. It is thought that this vaccine could lessen the impact of infection among children and significantly reduce mortality rates around the world.
Rotavirus is the causative agent for most cases of gastroenteritis among children globally. It was first shown to cause diarrhea in 1972 and was named the following year based on the wheel-like appearance of the virus. Of the several strains identified, Group A is associated with childhood gastroenteritis, while Groups B and C most often occur in adults. The disease is also called infantile diarrhea and winter diarrhea because outbreaks most commonly occur in infants and during the cooler months of winter.
Symptoms usually appear within 48 hours of infection and include fever, abdominal cramping, vomiting, and watery diarrhea, lasting up to eight days. Chronic conditions may result in severe fluid loss leading to dehydration, which is a common complication associated with gastroenteritis. Signs of dehydration include dry lips, a dry tongue, dry skin, and sunken eyes. While dehydration is readily treatable, it is responsible for the fatalities associated with infections of this kind.
Rotavirus infections are highly contagious and are transmitted via the fecal-oral route. The highest incidence is among infants and children, where good hygiene is difficult to maintain. Following ingestion, the viral particles imbed in the mucosal layers of the small intestine and may be passed in excretions. The virus is very stable in the environment and infection may result from ingestion of contaminated food and water or from contact with contaminated surfaces, such toys or tables. Prior infection does not produce complete immunity, but subsequent infections are usually less severe than the primary infection.
Rotavirus is responsible for an estimated 130 million cases of diarrhea worldwide annually and over 500,000 deaths. In the United States, over 3 million cases occur annually and over 55,000 children are hospitalized as a result. The availability of health care makes fatal cases of rotavirus rare in the United States.
The ability of the virus to persist in the environment enhances the threat of infection among all societies. In the United States, the disease is usually seen in the winter with annual epidemics most often occurring between the months of November and April. In developing nations, the virus circulates all year as a result of poorer access to clean water and health care. Outbreaks are common due to the way in which the virus is transmitted and to the fact that contamination of a major water source often results in infection for everyone using that supply.
The highest rates of infection occur among infants and children. In developed nations, rotavirus is most likely to occur before a child's second birthday. Children between the ages of 6 and 24 months who attend day care are at higher risk for rotavirus infection. This is due to the fact that these locations commonly harbor diseases transmitted by the fecal-oral route, and the fact that it is difficult to ensure the maintenance of good hygiene practices, such as handwashing, at this young age.
Adults tend not to develop the disease and adults in contact with the virus typically only develop a mild infection. Most instances of adult infection occur in elderly people and those with compromised immunity, such as transplant patients, chemotherapy patients, and people with human immunodeficiency virus (HIV).
In persons with intact immunity, the infection is selflimiting and symptoms will resolve within a few days of onset. While there is no specific treatment for the infection itself, oral rehydration therapy is essential and acts to restore the fluid lost as a result of severe dehydration. In developed countries, electrolyte and fluid replacement solutions are readily available over-the-counter, although serious cases of dehydration may require hospitalization for intravenous treatment. Substantial rehydration options are much more limited in developing nations and, in cases of contaminated water supply, drinking the contaminated water further contributes to the infection rather than helping to treat the symptoms of the infection.
The environmental stability of rotavirus means that basic hygiene is often not enough to prevent infection. Improvements in food, water, and sanitation do not often reduce disease incidence, although they may be employed to limit the spread of the infection. In day care settings, monitoring children to ensure that they are correctly washing hands after toilet use and during food preparation can reduce the spread of the disease.
A combined vaccine of all four strains of rotavirus known to cause severe gastroenteritis was approved for use in 1998. However, the vaccine was later withdrawn due to potentially fatal side effects involving blocking or twisting of the intestine. In 2006, the U.S. Food and Drug Administration approved a vaccine for use in the United States. A second vaccine was approved for use in Europe in 2006. The Rotavirus Vaccine Program (RVP) was established in 2003 by PATH with the support of the World Health Organization and the Centers for Disease Control and Prevention. The goal of RVP is to make the vaccines available in developing countries.
Rotavirus is responsible for 20–70% of hospitalizations and up to 800,000 of the 3 million deaths per year from diarrhea in developing nations. Within these communities of limited resources, these infections almost always result in severe symptoms and carry a significant mortality rate.
WORDS TO KNOW
DEHYDRATION: Dehydration is the loss of water and salts essential for normal body function. It occurs when the body loses more fluid than it takes in. Water is very important to the human body because it makes up about 70% of the muscles, around 75% of the brain, and approximately 92% of the blood. A person who weights about 150 pounds (68 kilograms) will contain about 80 quarts (just over 75 liters) of water. About two cups of water are lost each day just from regular breathing. If the body sweats more and breathes heavier than normal, the human body loses even more water. Dehydration occurs when that lost water is not replenished.
FECAL-ORAL ROUTE: The transmission of minute particles of fecal material from one organism (human or animal) to the mouth of another organism.
REHYDRATION: Dehydration is excessive loss of water from the body; rehydration is the restoration of water after dehydration.
STRAIN: A subclass or a specific genetic variation of an organism.
In developed countries, the fatalities associated with rotavirus infection are significantly lower, with only around 100 of the 3 million cases resulting in death. However, in these areas, the rate of infection is still quite high and therefore poses other issues for communities. The economic impact of the disease is significant, since infected children account for over 500,000 physician visits, over 50,000 hospitalizations, and an estimated $300 million in medical costs each year.
Recognition of the impacts associated with diarrhea caused by rotavirus led to extensive research to develop vaccines against this disease. The development of the vaccine against rotavirus is expected to reduce the incidence and severity of rotavirus infections in developed countries. However, the successful development of a vaccine brings with it numerous issues regarding not only affordability, but also availability to communities in developing countries. Immunization at a cost of $10– 20 per dose may be cost effective in industrialized countries, but is generally impractical in developing nations where per capita health care expenditure is less. This suggests that the global defense against rotavirus infection will require the cooperation of national governments and international agencies.
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National Institute of Allergy and Infectious Disease (NIAID). “Rotavirus Vaccine: Preventing Severe Diarrheal Disease in Infants.” May 25, 1999 <http://www.niaid.nih.gov/Publications/discovery/rotav.htm> (accessed March 12, 2007).
Rotavirus Vaccine Program (RVP). “About RVP.” 2007. <http://www.rotavirusvaccine.org/about.htm> (accessed March 12, 2007).