On the Malaria Vaccine

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

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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Water Availability

Though water is the body’s principal chemical component the World Health Organization (WHO) reports that 1.1 billion people lack access to a potable water source. In addition, approximately 2.6 billion people – half the population of the developing world – do not have access to even a simple latrine. While this raises concerns regarding quality of life and lack of resources in general, individuals who do not have access to clean drinking water and sanitation services are at an increased risk of contracting diarrheal illnesses, including cholera. Though these conditions are easily treated, the regions where they are most prevalent frequently also do not have the necessary medications. By increasing awareness about ways to improve the availability of safe water and sanitation services, it may be possible to reduce transmission and infection rates.

Reports indicate that each year the deaths of 1.6 million people – approximately 90 percent of them children under five years of age - are due to diarrheal illnesses that can be attributed to a lack of access to safe drinking water and basic sanitation. The WHO defines “basic sanitation” as “the lowest-cost technology ensuring hygienic excreta and sullage disposal.” Further, individuals are said to have “access to drinking water” - “drinking water” defined by the WHO as “water which is used for domestic purposes, drinking, cooking and personal hygiene” - if they are within 1 kilometer of a source that can reliably produce 20 liters per household member per day. According to Siemens, more than a billion people worldwide currently survive on only 3.8 liters (one gallon) of water per day, though experts suggest an intake of approximately 1.5 liters per day.

According to UN Secretary-General Ban Ki-moon, over the past decade, the number of individuals living in urban areas who lack access to drinking water in their home or the immediate vicinity has increased by an estimated 114 million, while the number who lack access to basic sanitation facilities has risen by 134 million. An estimated 51 million people in the Democratic Republic of Congo have no access to safe drinking water, and between 30 and 60 percent of the urban population of sub-Saharan Africa has no access to the municipal water supply. In these and other regions worldwide where access to potable water and sanitation services are limited, individuals may employ alternative methods of purifying water, such as boiling, chemical disinfection, and filtration. While these methods offer an effective means of generating a supply of safe drinking water, the quality of water used in farming is also critical, as water-borne pathogens on crops can cause diseases such as typhoid and cholera.

Both governmental agencies and non-profit organizations have established initiatives aimed at increasing the availability of water, purifying existing water sources, and improving sanitation services worldwide. By ensuring that safe water is available for consumption and farming, and that sanitation services are sufficient, the transmission of water-borne illnesses can be mitigated. In addition, providing individuals in regions facing shortages of potable water with information about water purification options and treatments for cholera and other diarrheal illnesses can improve the healthcare infrastructure in these areas.

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Zoonotic Diseases

A reported 75 percent of recently emerging infectious diseases are of animal origin, and approximately 60 percent of all human pathogens are zoonotic. Zoonotic diseases (zoonoses) are defined as illnesses commonly found in animals that can be transmitted to humans, and can be caused by bacteria, parasites, fungi, and viruses. To date over 200 zoonotic diseases have been identified, and though seen worldwide, zoonotic diseases are especially prevalent in areas of the developing world where humans and livestock live in close proximity. By gaining an understanding of these illnesses and tracking their spread, it may be possible to limit new infections and prevent potential epidemic outbreaks.

Outbreaks of zoonoses including influenza, ebola, tuberculosis, and severe acute respiratory syndrome (SARS) have been seen worldwide in recent years. In many developing countries, zoonoses are among the diseases that contribute significantly to an already overly burdened public health system. Approximately 700 million people in developing nations keep livestock, frequently living nearby the animals, putting them at an increased risk of contracting a zoonotic disease. Brucellosis (one of the world’s most widespread zoonoses), Q Fever, and Bovine spongiform encephalopthy (BSE or “mad cow disease”) are among the zoonoses commonly encountered in regions where large numbers of farm animals are kept.

The transmission of pathogens between the environment, wildlife, livestock, and humans is a major health concern that affects humans and domestic animals, as well as impacting the sustainability of agriculture and the conservation of wildlife. According to Dr. Martyn Jeggo, director of CSIRO’s Australian Animal Health Laboratory, the recent emergence of diseases in humans which originated animals has “heightened public awareness of the multidimensional linkages between wild animals, livestock production, the environment and global public health.” In addition to those transmitted by farm animals, recent studies suggest that at least 100 of the known zoonotic diseases are derived from domestic pets. According to Dr. Peter Rabinowitz of the Yale School of Medicine, rates may be higher than studies indicate as several million infections passed between pets and people go unreported each year in the United States. Common infections transmitted to humans after sleeping with their cat or dog, or being licked by the animal include hookworm, ringworm, roundworm, cat scratch disease, and drug-resistant staph infections.

According to experts, the key to slowing the spread of zoonotic diseases and reducing the likelihood of epidemic events is careful monitoring. Through programs like the recently launched PREDICT, a project of USAID's Emerging Pandemic Threats Program, it may be possible to develop a global early warning system through which emerging zoonotic diseases can be detected and reduced.



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On Polio Worldwide

Though cases of polio worldwide have been reduced by 99 percent since 1988, it continues to be a major public health concern in Afghanistan, India, Nigeria, and Pakistan. Recent outbreaks have also been seen in the Congo Republic. Vaccination programs have been put in place in the hopes of eradicating the disease, but according to experts, infection in even one individual can put an entire population at risk. Though previous vaccination efforts helped to reduce the number of cases in many regions, in Nigeria and some other African nations the social stigma and fear associated with vaccinations must be overcome. By utilizing a newly developed, more effective polio vaccine and working to educate individuals about the importance of getting vaccinated, it may be possible to meet the Global Polio Eradication Initiative’s (GPEI) goal of eradication polio worldwide by 2013.

Polio (poliomyelitis) is a contagious viral illness that, in its most severe form, can cause paralysis, difficulty breathing, and death. Often contracted through contact with the feces of an infected person, polio can be spread through contaminated food or water, and the risk of contamination is particularly in areas with poor sanitation. Though individuals of all ages can contract polio, children under five years of age, pregnant women, and individuals with weakened immune systems are even more vulnerable. Ninety-five percent of individuals infected with polio have no symptoms, and between four and eight percent experience minor, flu-like symptoms including fever, fatigue, and stiffness or pain in the back, neck, or limbs. Individuals with polio who show no symptoms or only minor symptoms may still spread the virus to others.

Though infection rates of non-paralytic and paralytic polio were significant in the 1950s in the United States and other areas worldwide, in recent years fewer than one percent of individuals who contract polio develop paralytic polio, the most serious form of the disease, which can lead to loss of reflexes, severe muscle aches and spasms, and paralysis. Paralytic polio can manifest in a variety of ways, and is classified by the areas of the body that are most affected. Spinal polio, the most common form of paralytic polio, attacks the motor neurons in the spinal cord and may cause paralysis of the muscles that control breathing and movement of the arms and legs. Bulbar polio affects the motor neurons of the brainstem, impacting an individual’s ability to see, hear, smell, taste, and swallow, and may also affect intestine, heart, and lung function. A combination of both, bulbospinal polio can lead to paralysis of the limbs, as well as affecting breathing, swallowing, and heart function.

The lack of a cure for polio and limited treatment options available underscore the need for effective vaccination campaigns. Inactivated polio vaccine (IPV), an injection given in the arm or leg, has been used in the United States since 2000. Most children in the U.S. are given four doses of IPV, which has been found to be 90 percent effective after two shots, and 99 percent effective after three. The oral polio vaccine (OPV) is used throughout much of the world, but may soon be replaced by the newly developed bivalent oral polio vaccine (bOPV). The bOPV contains two key strains of the virus and thus may provide improved inoculation results. In addition to efforts to increase vaccination rates, improved sanitation and education related to personal hygiene can help to reduce the spread of polio, as well as cholera and other water-borne illnesses.

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