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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Autism Spectrum Disorders

February 22, 2010

Debates regarding recent changes to the guidelines for diagnosis of Asperger syndrome, often considered a high-functioning form of autism which inhibits the ability to interact socially and causes repetitive behaviors, are ongoing. According to the Centers for Disease Control and Prevention (CDC), one in 110 children have an Autism Spectrum Disorder (ASD). Time Magazine reports that researchers at the University of Leicester, working with the NHS Information Center found that roughly 1 in 100 adults exhibit an ASD. Though the exact cause for these conditions is not known, the rate at which they are occurring is increasing. The Centers for Disease Control and Prevention indicate that autism and related disorders are more common than previously thought, though it is unclear if this increase is due to an improved ability to diagnose.

A developmental disorder that appears in the first three years of a child’s life, autism affects the brain’s development of social and communication skills. One in every 110 8-year-old children, and one of every 70 boys, in the United States has been diagnosed with autism. The CDC indicates that; per the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision and International Classification of Diseases, Tenth Revision; “criteria have identified ASD rates ranging from 2.0 to 12.0 per 1,000 children” worldwide. Individuals with autism may repeat body movements, have difficulty communicating, and avoid social interaction, including physical contact. Findings from a study of mice with Fragile X Syndrome, a condition that is often linked to autism, indicate that delayed development in the sensory cortex of the brain may be the cause of autistic individuals’ aversion to touch. Dr. Gina Gómez de la Cuesta, from the National Autistic Society, notes that “Autism is common in people with fragile X syndrome, however there are many other causes of autism, most of which are not yet fully understood.”

Efforts to identify causes, treatments, and prevention measures for the disorder are ongoing. Some advocates maintain that diets removing gluten (found in wheat, barley, and rye) and casein (found in dairy) alleviate some of the symptoms of autism, however there has not been any scientific documentation of the success of these restricted diets. A now-discredited study published in the Lancet in 1998 indicated a link between autism and the measles, mumps, and rubella vaccine frequently administered in early childhood. According to experts, the frequency with which autism symptoms become more apparent at two years of age when receiving these vaccinations, is coincidental, as childhood vaccines do not cause the disorder.

New research indicates that babies born prior to the 26th week of pregnancy, are at a higher risk of developing autism. A recent study showed eight percent of 219 children born in this timeframe, met the criteria for an ASD at the age of 11. A comparison group of 153 children born full-term were also included in the study, none of whom exhibited signs of autism or other ASDs. The age of both parents has also been linked to a child’s likelihood of developing an ASD. Data collected from 4.9 million births in the 1990s in California indicated that compared with women in their mid- to late-20s, women giving birth after 40 had a 50 percent increase in the risk of having an autistic child. The father’s age was also found to impact the likelihood of having a child with autism, but only in the case of men over 40 having children with women under 30.

Recent research indicates a correlation between a deficiency in oxytocin, a hormone that makes women more maternal and men less shy, and autism or Asperger syndrome. In a study of 13 adults with high-functioning autism or Asperger syndrome, use of a nasal spray containing oxytocin was found to improve scores on a test involving recognition of faces. This type of medical intervention could provide an additional treatment option for children and adults with ASDs who are currently involved in behavioral interventions. Though often expensive, structured behavioral interventions and early intervention programs have been found to improve the language skills of children with ASDs, sometimes increasing the IQ of children as many as 18 points. Direct medical and non-medical costs for an individual with an extreme case can total as much as $72,000 per year. Medications, clinical visits, and occupational and speech therapy, as well as special education, camps, and child care are just some of the expenditures of parents of children with autism. As individuals with autism grow into adulthood, these costs continue, as caregivers and specialized programs may be needed.

There is still no known direct cause for autism and other ASDs. These conditions can put an emotional and economic strain on families, and can lead many parents to blame themselves for their children’s condition. With improved diagnostic tools and earlier diagnoses, children with autism can receive early intervention treatments and education to improve their outcomes.

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The Flu Vaccine

October 12, 2009

As new cases and concerns about seasonal flu and swine flu (H1N1) continue to spread worldwide, two vaccines have recently been made available. Both the nasal spray vaccine and injectable vaccine for seasonal flu have proven effective for specific portions of the population, however distribution is still slow. For the H1N1 (swine flu) virus, The Baltimore Sun reports, availability is still an issue and many areas have not yet received enough doses to meet the demand. While many in the developed world do not yet have access to the H1N1 vaccine, Dr. Bernadine Healy notes that the problem is even greater in the developing world. To help these nations fight the pandemic, the United States has agreed to donate 10 percent of its vaccination supply to the World Health Organization (WHO) – eight other nations will make similar donations.

Fantastic Image by Deborah Ervin

Inoculating individuals for both viruses is complicated by the time frame in which the vaccinations can occur. If one chooses nasal spray for both seasonal and swine flu, they must wait four weeks between doses, while if one is injected for one virus and uses nasal spray for the other, they can be administered together. Discovery Health reports that doctors recommend annual flu shots to lessen the chances of becoming ill. Individuals as young as six months can be inoculated, according to the Centers for Disease Control and Prevention (CDC) and side effects are reported to be minor. Because the virus used to make the seasonal flu vaccine is dead, it is not possible to contract flu from a flu shot, however one may expect a low-grade fever 8 to 24 hours following injection, a swollen or tender area around the injection site, a slight headache or chills within 24 hours.

The seasonal flu shot is an inactivated vaccine, and contains three influenza viruses – one A(H3N2) virus, one regular seasonal A(H1N1) virus (which differs from the 2009 H1N1 virus), and one B virus. The viruses used change annually based on international surveillance which track infection trends and scientists estimations about which strains will circulate during the year. In contrast to the flu shot, the nasal-spray flu vaccine contains a weakened but still living flu virus, sometimes called LAIV (live attenuated influenza vaccine). These nasal mists are approved for use in healthy individuals ages two to 49 who are not pregnant. In addition to nasal sprays, Discovery Health reports that researchers at Stanford University and the University of Alabama at Birmingham have been working with naked DNA in an effort to develop a vaccine that could be delivered via shampoo or dermal patch.

Three recent large-scale studies, including a study led by Dr. Arnold S. Monto of the University of Michigan, indicate that while the seasonal flu shot is more effective for adults and safe for women who are pregnant, the intranasal vaccine (nasal spray) is more effective at preventing flu in children. These studies showed 35 to 53 percent fewer cases of flu in children who were given the nasal spray vaccine than those who received injected vaccines. The Los Angeles Times reports that injectable vaccines prevent roughly 50 percent more seasonal flu in healthy adults than the nasal spray vaccines.

Due to the relative newness of the H1N1 vaccine, health authorities have implemented a number of tracking measures to ensure its safety. The Associated Press reports that Harvard Medical School scientists are working to link insurance databases covering 50 million people with vaccination registries to allow them to determine if people visit a doctor after being vaccination as well as the reason for the visit. Johns Hopkins University and the CDC are also working to ensure that any side effects are noted and addressed quickly. These efforts include emailing individuals who have been vaccinated recently to see how they are feeling (Johns Hopkins), and preparing take-home cards asking vaccine recipients to report any side effects to the nation’s Vaccine Adverse Event Reporting system (CDC). These measures are being undertaken as in the Internet-age, the Associated Press notes, one person updating their Facebook status to say that they got a flu shot and feel sick could cause a wave of similar reports.

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Associated Press on the Nasal Spray Flu VaccineThe New York Times on CDC Side Effect Tracking Measures