On the Malaria Vaccine

November 7, 2011

A recent WHO report indicates that nearly a third of all countries affected by malaria are on course to eliminate the disease over the next 10 years. Though malaria can lead to complications or even death, it is a preventable and curable illness caused by a parasite that is passed from one human to another through the bite of infected Anopheles mosquitoes. Infected individuals frequently experience high fevers, flu-like symptoms, and anemia; and in 2008 malaria caused between 190 and 311 million clinical episodes and between 708,000 and 1,003,000 deaths. Anti-malarial medications, insecticidal nets, and other control and prevention measures have saved an estimated 1.1 million lives in Africa over the past 10 years, but the availability of an effective vaccine  is vital to halt its spread.

In the 109 countries and territories where the risk of malaria transmission is the greatest, newly developed malaria vaccines could save lives. Reports indicate that there were 225 million cases of malaria and an estimated 781,000 deaths in 2009, but these figures have steadily declined in recent years. Though preventative measures have helped to reduce infection rates, experts note that the development and use of a malaria vaccine could reduce them further. During a major clinical trial,  a recently produced experimental vaccine known as RTS,S halved the risk of children in Africa contracting malaria. Currently children under five years of age account for the majority of the 800,000 people who die each year as a result of malaria. According to the developers of the vaccine, the adverse effects observed during the vaccine trial are comparable to those seen in children receiving other vaccines.

The RTS,S vaccine triggers an immune response which targets the Plasmodium falciparum parasite that causes malaria. This immune response prevents the parasite from maturing and multiplying in the liver of the vaccinated individual. Unlike other previously developed malaria vaccines, this new vaccine has been created to target different forms of the disease and to trigger a range of antibody responses. Though researchers have been working for 40 years to develop an effective malaria vaccine, to date the outcomes have not been entirely successful. Additional research and testing of the RTS,S vaccine is needed, but according to Dr. Mary Hamel of the Centers for Disease Control and Prevention, “these findings show we are on track in the development of a vaccine.”

With further testing and refinement, this vaccine has the potential to save millions of lives each year and eradicate a disease that affects 3.3 million people – half the world’s population. An effective malaria vaccine could reduce malaria-related deaths, 89 percent of which occur in Africa, and could improve the lives of individuals in regions impacted by the diseases.

 

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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 MRSA Infections Worldwide

June 20, 2011

Methicillin-resistant Staphylococcus aureus (MRSA) infection has become increasingly common in recent years, due in large part to overuse of antibiotics. According to a 2007 report in Emerging Infectious Diseases, a publication of the Centers for Disease Control and Prevention (CDC), the average number of MRSA infections doubled nationwide between 1999 and 2005 – from 127,000 to 278,000. During the same period, the number of annual deaths from MRSA infection increased from 11,000 to more than 17,000. By increasing awareness about the risk factors associated with and steps that can be taken to avoid MRSA infection, it may be possible to reduce or eliminate its spread.

MRSA infection is caused by a strain of Staphylococcus (staph) bacteria that has become resistant to the antibiotics commonly used to treat staph infections, which include methicillin and penicillin. Generally, MRSA is spread through skin-to-skin contact, openings in the skin (cuts or abrasions), contact with contaminated surfaces, crowded living conditions, or poor hygiene. MRSA frequently manifests first on the skin as a reddish rash with lesions resembling pimples which may begin to drain pus, or lead to cellulitis, abscesses, and impetigo. In addition, the initial skin infection can spread to almost any other organ in the body, resulting in more serious symptoms and potential complications.

Designations are made between types of MRSA infection based on the location where the infection took place. Hospital-acquired MRSA (also called health-care-acquired, HA-MRSA, or HMRSA) remains one of the most common types of infection. Individuals who are hospitalized, those with invasive medical devices such as catheters, and those residing in nursing homes are at an increased risk of acquiring HA-MRSA. Community-acquired MRSA (CA-MRSA or CMRSA) is another common type of infection, and is seen most frequently in individuals participating in contact sports or those living in crowded or unsanitary conditions. While the average adult death rate among individuals with MRSA is estimated at five percent of infected patients, individuals with HA-MRSA are at an increased risk of experiencing complications including organ damage.

Dr. Marc Siegel, an associated professor of medicine at New York University, and others recommend an evaluation of the overuse of antibiotics by humans as well as in livestock as a means of eradicating MRSA and reducing drug resistance in other strains of bacteria. In addition, experts note the importance of good hygiene practices  including washing hands frequently, keeping wounds covered with bandages until they have healed, and washing soiled clothes and sheets in hot water can help to prevent the spread of MRSA. The timely diagnosis of individuals infected with MRSA achieved through an analysis of a skin sample helps to better ensure not only treatment for the individual, but also a decreased risk of infecting others.

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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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