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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West Nile Virus

August 23, 2010

West Nile virus (WNV) is an infection transmitted to humans and animals by mosquitoes which have fed on infected birds. According to the Centers for Disease Control and Prevention (CDC), between 1999 and 2008, 28,961 confirmed and probable cases of WNV were reported. Though 80 percent of individuals infected with WNV show no symptoms, approximately one in 150 develop severe illness with symptoms including high fever, vision loss, and paralysis. Though there is no vaccine or cure for WNV, it is important for individuals to have an understanding of how best to protect themselves from infection.

First identified in Uganda in 1937, WNV occurs when Culex pipiens mosquitoes feed on infected birds, which serve as vectors for the virus, and then pass the virus on to humans. WNV cannot be passed from one individual to another through close personal contact, and the primary method of transmission is through the bite of an infected mosquito. Mild infections (West Nile fever) are seen in approximately 20 percent of individuals, and are marked by symptoms including fever, headache, and body aches. Individuals with severe infections (severe West Nile disease) may experience inflammation of the brain (encephalitis) or of the brain and surrounding membranes (meningoencephalitis), and three to 15 percent of WNV infections result in death. According to CDC statistics, in 2009 there were a total of 663 cases of WNV in the United States, and 30 of these resulted in death.

The CDC indicates that WNV is an established seasonal epidemic in North America, beginning in the summer and continuing into the fall. In addition to documented cases in the United States, both sporadic cases and major outbreaks of encephalitis related to WNV have been reported in Africa, West Asia, Australia, Europe, and the Middle East. Recent reports have documented outbreaks in Greece and British Columbia, Canada; as well as in New York, Pennsylvania, and northwestern Indiana.

Like malaria, dengue, and other mosquito-borne illness, rates of WNV infection increase during periods of warm weather when mosquito populations are most active. Torrential rains in early summer and persistent high humidity in many regions of the United States have created the ideal breeding climate for mosquitoes. Experts recommend taking preventative measures to avoid infection including the “5 D’s”:

  • Dusk and Dawn – avoid being outdoors during these periods which are when mosquitoes are most active
  • Dress – wear clothing that limits exposed skin
  • DEET – use repellents containing DEET (picaridin and oil of lemon eucalyptus are other repellant options)
  • Drainage – eliminate areas of standing water in which mosquitoes lay eggs.

In addition, dead birds, particularly crows, which display signs of illness should be reported to authorities for proper disposal. As health officials continue to track outbreaks of WNV, individuals can take appropriate measures to limit their risk of infection and keep their community healthy.

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On Malaria Worldwide

May 3, 2010

Nearly half the world’s population – roughly 3.3 billion people – are at risk of contracting malaria. Though individuals in Latin America, the Middle East, and Europe are among those most often affected by the disease, the Centers for Disease Control and Prevention reports that 98 percent of global malaria deaths occur in 35 countries – 30 of them in sub-Saharan Africa and five in Asia. Every year there are nearly 250 million cases and an average of one million deaths due to malaria. Reports show that in 2008, an estimated 863,000 people died from malaria infection, indicating some improvement in diagnosis and treatment outcomes. Transmission is possible to any individual, however some groups are at an increased risk. These include young children who have not yet developed full immunity, pregnant women whose immunity has been decreased by pregnancy, international travelers who lack immunity, and  individuals with HIV/AIDS or others with compromised immune systems.

Malaria is a preventable and curable acute febrile illness caused by the bite of Anopheles mosquitoes which have been infected with Plasmodium parasites. The long lifespan of the Anopheles species found in Africa contributes to the disease’s prevalence in the region, and experts note that more than 85 percent of the world’s malaria deaths occur in Africa. Symptoms are usually seen seven days after the infective mosquito bite, and include fever, headache, chills, and vomiting. If diagnosed quickly, malaria can be treated using artemisinin-based combination therapy (ACT), however if treatment is not initiated, malaria can progress and lead to severe anemia, respiratory distress, or death.

In countries where malaria is endemic, access to diagnostic tools and medications may be limited. Less than 15 percent of these individuals are able to begin treatment within 24 hours of the onset of fever, which is when treatment must be started. Malaria diagnosis relies on either microscopy or rapid test procedures to allow healthcare providers to quickly determine if patients have the disease and require treatment. The Malaria Product Testing Evaluation Programme recently completed an assessment of 29 rapid diagnostic tests and found that 16 of them met the minimum performance criteria set by the WHO. According to Robert Newman, the director of the WHO’s Global Malaria Programme, using rapid tests allows healthcare providers to “test people who cannot access diagnosis based on microscopy in remote, rural areas where the majority of malaria occurs” and thus improves treatment outcomes.

In addition to improved testing, global efforts are underway to control malaria by eliminating the mosquitoes that transmit the disease. During the past decade, the distribution of treated bed nets has increased rapidly in 11 African nations, helping to reduce infection rates. Reports indicate that in 2008, 31 percent of African homes had insecticide-treated nets (ITNs), compared with 17 percent in 2006. Through the use of ITNs, as well as spraying of homes with insecticide chemicals, 10 African nations reduced the number of cases of malaria by at least 50 percent between 2000 and 2008.

Though there is no vaccine for malaria, more effective prevention measures, diagnostic tests, and medications can help to improve treatment outcomes for those affected. Government agencies, including the World Bank, and other groups, such as Roll Back Malaria global partnership, have made efforts to increase global awareness about malaria. By utilizing social media and online tools it has been possible to improve the effectiveness of outreach and fundraising for efforts which may help to eradicate malaria worldwide.

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