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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On Chickenpox Worldwide

August 29, 2011

Chickenpox was once considered a rite of passage for most children, but since the establishment of routine vaccination programs, complications from the virus have seriously decreased. While the condition very seldom leads to secondary infections or other issues, it is highly contagious and can be problematic in some individuals. It is important that parents ensure their children receive vaccinations for chickenpox and other common childhood illnesses, and remain mindful when interacting with infected individuals.

In the 16th century, the varicella zoster virus (VZV), the virus that causes chickenpox was identified, but it was not until the end of the 19th century that physicians were able to reliably distinguish chickenpox from smallpox. VZV is a member of the herpes virus group, and like other herpes viruses, it has the capacity to persist in the body after the first infection as a latent infection and can reappear as shingles. Shingles, which manifests as a painful rash on one side of the body, occurs in approximately one in 10 adults. It is the result of re-activation of the VZV virus which persists as a latent infection in sensory nerve ganglia and can occur in any individual who has recovered from chickenpox, but it is most common in individuals over 60.

Spread through direct contact with the rash or droplets dispersed into the air by coughing or sneezing, chickenpox manifests as a red, itchy rash which first appears on the face, trunk, or scalp. The rash usually appears 10 to 21 days after infection, and may be accompanied by a fever, abdominal pain, headache, and a general feeling of unease and discomfort. If scratching the rash is not discouraged through the use of oatmeal or baking soda baths, the application of calamine lotion, or antihistamines, individuals may contract a bacterial infection of the skin. Other complications that can result from chickenpox include viral pneumonia, bleeding problems, and infection of the brain (encephalitis).

Before the introduction of a vaccine, approximately 10,600 people were hospitalized and 100 to 150 died as a result of chickenpox in the U.S. every year. Vaccination became routine practice in the U.S. in 1995, and there are now two live, attenuated VZV-containing vaccines available for use. Recent studies have shown that in children, two doses of the chickenpox vaccine is 98 percent effective in preventing infection, compared with 86 percent effectiveness for a single dose. Recommendations from the Centers for Disease Control and Prevention and the American Academy of Pediatrics indicate that children should receive their first shot at 12 to 15 months, and the second at four to six years to ensure the maximum benefit. While a reported 15 to 20 percent of vaccinated individuals do still become infected with chickenpox if they are exposed to it, their condition is significantly milder and lasts for a shorter period of time.

By increasing awareness about the importance of vaccination, it may be possible to further decrease rates of infection and complications associated with chickenpox. Vaccination against chickenpox and other childhood illnesses can not only protect the individual receiving the vaccination, but can help to protect individuals who may not be able to receive vaccinations due to health conditions by contributing to the herd immunity of their community

 

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On Measles Worldwide

May 23, 2011

The World Health Organization reports that in 2008, there were 164,000 measles deaths globally, more that 95 percent of which were in low-income countries with weak health infrastructures. This rate equates to nearly 450 a day or 18 per hour. In recent years, targeted vaccination campaigns have greatly reduced the number of measles deaths each year, though in developing nations with weak health infrastructures complications or deaths related to measles infection are still not uncommon. By increasing awareness about the importance of vaccination and making vaccines available in regions where they are needed, the virus that causes measles could be eradicated.

Measles, also called rubeola, is a common and preventable childhood disease, also sometimes seen in individuals with compromised immune systems. Most frequently, infection is marked by a fever lasting a couple of days, followed by a cough, runny nose, and conjunctivitis.  Soon after, patients exhibit a rash on the face and upper neck, spreading down the back and trunk to the arms and legs. Reports indicate that 30 percent of people infected with measles will experience complications, ranging from ear infections to pneumonia. Further, one in every 1,000 people will develop inflammation of the brain. If left untreated, the complications associated with measles infection can be life threatening. In regions without widespread access to medical care, an estimated five percent of children die of measles-related causes.

According to William Schaffner, an infectious disease expert at Vanderbilt University School of Medicine, the measles virus infects more than 80 percent of unvaccinated people exposed to it. Though the transmission of endemic measles was declared eliminated in the U.S. in 2000, the disease remains common in other regions and can be imported by travelers. Reports from the Centers for Disease Control and Prevention (CDC) indicate that during 2008, nearly 90 percent of measles cases in the U.S. were either acquired abroad or linked to imported cases. While a safe and cost-effective vaccine is available, more than 20 million people are affected by measles each year and the majority live in developing nations and/or countries with low per capita incomes and weak health infrastructures.

Though measles outbreaks continue to be problematic in some developing regions, the World Health Organization reports that between 2000 and 2007, 576 million children were vaccinated against measles, resulting in a 74 percent decrease in measles-related deaths worldwide. By increasing awareness about the importance of vaccinations and ensuring that vaccines for measles are available, rates of infection, complications due to infection, and death could be even further reduced.

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