Salmonella Infection

September 26, 2011

Bacteria of the Salmonella genus are a major cause of food-borne illness worldwide. Symptoms in most individuals infected with Salmonella are not life-threatening, however in young children, the elderly, and individuals with compromised immune systems, Salmonella infection can be significantly more harmful. By ensuring that food is prepared carefully and properly, it may be possible to reduce the infection rates of Salmonella.

Each year there are approximately 40,000 reported cases of Salmonella infection in the United States, and infection rates are higher in nations with poor sanitation. The majority of infected individuals experience diarrhea, fever, and abdominal cramps within 12 to 72 hours after infection. Though Salmonella infection usually resolves without medical intervention within 7 days, for some individuals dehydration related to diarrhea may become severe and require hospitalization. In addition, a small number of infected individuals develop pain in their joints, irritation of the eyes, and painful urination.

Two serotypes of the approximately 2,500 that have been identified, Salmonella Enteritidis and Salmonella Typhimurium are the most common in the United States and account for half of all human infections. In addition to these common strains, antibiotic strain of Salmonella has recently been identified in 26 states, and to date it has sickened 77 people and killed one. Salmonella infection occurs when the bacterium are ingested, and it is commonly accepted that between 1 million and 1 billion bacteria are needed to cause infection.

The majority of infections are due to the consumption of foods that have been contaminated with animal feces. In recent years, outbreaks have been associated with chicken, turkey, and other meats; as well as eggs, and spinach and a number of other vegetables. To help limit the possibility of infection, experts suggest that consumers follow food preparation guidelines aimed at ensuring that food is properly cleaned and cooked thoroughly. These include washing surfaces and hands frequently, keeping raw meat separate from other ingredients, and ensuring that foods are fully cooked and properly stored. By ensuring that food is handled appropriately, it may be possible to reduce rates of Salmonella infection.

 

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On Cholera Worldwide

November 1, 2010

Though the last major outbreak in the United States occurred in 1911, cholera remains a persistent health concern in many parts of the world, including Asia, the Middle East, Latin America, and sub-Saharan Africa. Recent outbreaks have been seen in Nigeria,  where cholera has killed more than 1,500 people this year, and in Haiti, where survivors of the massive January earthquake have been affected by an outbreak that has infected an estimated 2,300 people and killed at least 200. Due to cholera, there are an estimated three to five million new cases reported worldwide and between 100,000 and 120,000 deaths each year. Like other diarrheal illnesses, cholera is easily treatable and can be prevented through the provision of safe water, improved sanitation services, and education about the importance of hygiene.

Cholera

Cholera is an acute diarrheal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. Though three-quarters of individuals infected with V. cholerae do not exhibit any symptoms, they may shed the bacteria in their stool for seven to 14 days, potentially infecting others. While V. cholerae is the direct source of cholera infection, the deadly effects of the disease are caused by a toxin called CTX, that the bacteria produce in the small intestine of the host. CTX binds to the intestinal walls and interferes with the normal flow of sodium and chloride, causing the body to secrete large amounts of water and leading to diarrhea accompanied by dehydration. In individuals exhibiting the severe form of the disease, the rapid loss of fluids can lead to dehydration and shock, and without treatment death can occur within hours. Approximately one in 20 individuals infected with the bacteria develops symptoms associated with cholera, which include: severe, watery diarrhea; nausea and vomiting; muscle cramps; dehydration; and shock.

The rapid loss of fluids in a short period of time – often as much as a quart in an hour – associated with diarrhea due to cholera, makes the disease particularly deadly. In order to replenish the fluids and electrolytes that an individual with severe cholera has lost, Oral Rehydration Salts (ORS) must be administered. If a pre-formulated solution is not available, experts suggest combining one-half teaspoon salt, one-half teaspoon baking soda, and three tablespoons sugar in one liter of safe drinking water. With the prompt delivery of ORS, up to 80 percent of people can be treated successfully, with a fatality rate below one percent. Antibiotics may be used in conjunction with ORS to shorten the course and lessen the severity of the illness, however their delivery is less critical to cholera patients than rehydration. To help control the spread of the disease, two types of oral cholera vaccines are also available, but according to experts they provide only a short-term effect and should be administered in areas where ongoing water and sanitation improvement programs are in place.

Despite the simplicity of the cure, thousands of people die each year in regions that lack effective sanitation and water purification systems. Following man-made or natural disasters, the risk of an initial outbreak of cholera growing into an epidemic is greatly increased. As seen recently following floods in Pakistan and Nigeria, the spread of cholera becomes a major public health concern when there is a lack of clean water. By providing treatment as well as information about the importance of boiling water before drinking and maintaining personal hygiene, it may be possible to slow or even stop the spread of cholera and other communicable diseases.

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A Killer in the Developing World

August 17, 2009

HIV/AIDS and malaria are major health concerns worldwide, however the World Health Organization (WHO) reports across much of Asia and Africa secretory diarrhea – which accounts for 1.6 million deaths annually – is an even greater threat. Each day in India, diarrhea-related diseases kill 1,250 people, only slightly fewer than the H1N1 virus has killed globally to date (1,500), according to the WHO. Caused by E.coli, cholera, and other bacteria, viruses, or parasites, diarrhea affects individuals more often in areas that lack safe water and appropriate sanitation. In individuals with secretory diarrhea, infectious agents cause too much water to enter the bowel and be evacuated from the body, leading to excessive dehydration and eventually death if appropriate treatment is not received.

Diarrhea in the Developing World
In nations of the developing world, including Bangladesh, India, Mali, and Pakistan, aid organizations and government agencies have begun distributing zinc supplements to villagers as a treatment for diarrhea. Data from recent studies documented in the August 2009 issue of the Journal of Leukocyte Biology suggest that zinc may help to activate the T-cells needed to destroy viruses and bacteria, including those that cause diarrhea. Time Magazine reports that in tablet or liquid form, zinc can be used in combination with oral-rehydration therapy (ORT). While it is not entirely clear how zinc helps halt diarrhea, Oliver Fontaine, a diarrhea specialist for the WHO, explains that a single course of zinc treatment can stave off diarrhea for three months.

Unlike zinc, which often produces an immediate improvement in an individual’s health, the glucose present in ORT (a solution of sugars and salts) slows the evacuation of fluids allowing for the absorption of electrolytes in the intestines, and halting the progression of dehydration to a chronic state. Because of the delay in the improvement of symptoms with ORT, “Mothers don’t see ORT as real treatment,” according to Eric Swedberg, senior director of health and nutrition at Save the Children U.S. Though ORT is an effective treatment for diarrhea, only about 35 percent of families in diarrhea-stricken countries utilize the method.

By offering zinc in combination with ORT, government-run programs in Ethiopia and Tanzania hope to increase the number of people surviving diarrheal outbreaks. Additionally, efforts are being made in Mali to add zinc to the country’s list of essential drugs, a step towards improving the distribution of the tablets. To halt the recent outbreaks of diarrhea in Nepal that have led to 235 deaths to date, the Office of the Prime Minister has begun coordinating efforts to construct a toilet in each household, provide sources of potable water, and improve waste disposal systems. In addition, the Nepali government has mobilized 298 personnel to aid in providing treatment in the area through 89 health camps.

To support these and other similar efforts, funding for the provision of the potentially life-saving drugs, and awareness of their effectiveness must be increased. In 2007, only four percent of all U.S. funding for research of epidemics in the developing world was devoted to finding solutions to decreasing the number of diarrhea-related deaths. Support from organizations like the Bill and Melinda Gates Foundation have provided some support, but additional funding is still needed not only to ensure that zinc tablets are more widely distributed, but also to assist in efforts to improve the quality of available water and waste treatment measures.

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WHO on Water Treatment and Safe StorageOn Diarrhea and Tuberculosis in IndiaTime Magazine on Zinc to Treat DiarrheaDiarrheal Deaths in NepalOn Zinc Fighting Infection