Wednesday, October 28, 2009

Thursday, October 22, 2009

Progress in the war against invisible killers

In 2000, world leaders met at the UN in New York, to set up some Millennium Development Goals (MDGs) to be fulfilled by 2015. These goals included plans to eradicate malaria, HIV/AIDS, and Tuberculosis (TB). Upon reconvening in 2008, the assembly realizes the latter two of the 3 goals unrealistic and unattainable by 2015.

Malaria Current Goals: The leaders still seek to cut cases by 75%, 2000—2015, and malaria-caused deaths to zero. Progresses: Insecticide-treated use of bed nets has tripled in 16 of 20 sub-Saharan African nations since 2000. Free Artemisinin-based combination therapy (ACT) distributed at all public health facilities in Zanzibar, Tanzania, has reduced novel cases reported by 70%. Genomes of three major mosquito vectors have been sequenced. RTS S vaccine is going into phase III trials across large areas of Africa. Problems: It has been estimated that $900 million more per year is required to develop vaccines and novel insecticides.

HIV/AIDS Current Goals: Universal access to HIV-AIDS treatment by 2010 Progresses: Rate of new infections fell from 3 million in 2001 to 2.7million in 2007. AIDS death rate dropped from 2.2 million in 2005 to 2 million in 2007. Approximately 3 million people living in low income nations are now receiving anti-retroviral treatments. World leaders pledged another $500 million to achieve goals. Problems: Demand for treatments far exceeds supply. Prevention is exceedingly difficult due to scientific, political, and cultural reasons.

TB Current Goals: Treat 50 million TB-infected people and prevent 14 million deaths Progresses: Incidence has slightly decreased. Global TB-prevalence rate fell by 2.8% and the corresponding death rate fell by 2.6%. Problems: TB detection is lagging, particularly in Africa, China, and India. Drug treatments are difficult to control.

Stone, M. 2009. Determined Progress in War against Malaria, HIV-AIDS, and TB. Microbe 4:115—118.

The cost-effectiveness of the continuance of HIV vaccine research

In recent years much scientific literature has reported the repeated failures of potential HIV vaccines to pass the phase II and phase III trials. In 2008 a potential vaccine, developed by Merck, failed its phase III trial, for the second time. As a result, the NIAID (National Institutes of Allergy and Infectious Diseases), among others, began to debate and reconsider the cost and benefit of HIV vaccine research and development. In 2007-2008 Elisa Long, Margaret Brandeau, and Douglas Owens conducted a study assessing “the outcomes for a broad range of vaccine efficacy and costs, and the outcomes associated with either universal vaccination or vaccination targeted to high-risk groups.”

Demographic information of currently reported HIV-positive individuals in the U.S, including behavioral patterns, was extrapolated using a set of differential equations to establish a model simulating the HIV epidemic over a 20 year period. This model depicts the proposed transmission and progression of HIV/AIDS and the cost-effectiveness for various vaccine strategies. They took into account several variables, such as the thought that antiretroviral therapy would decrease an individual’s infectivity thus possibly reducing transmission probability; however, increased life-expectancy of individuals would also increase measure of sexual activity and/or needle-sharing behaviors thus potentially increasing transmission.

They estimated that without any vaccine program in place, 1.29 million new HIV cases would occur over a 20 year period. They projected that a universal vaccination program, with a 75% efficacy and lifetime duration, would prevent 912,000 cases (71%) over the 20 year period, with 196 million individuals being vaccinated. A vaccination program targeting uninfected high-risk groups could result in 774,000 cases (60%) being prevented, with 9 million individuals being vaccinated. Finally, the less efficient strategy, by targeting low-risk individuals, 187 million individuals would require vaccination in order to return a reduction by 110,000 cases (12%). The model also suggests that for only a 5 to 10-year protection period, still with 75% efficacy, and universal vaccinations, approximate 420,000 — 610,000 cases can be prevented. Vaccinating high-risk groups would, obviously, greatly reduce the prevalence of HIV among those individuals, but could also significantly decrease the prevalence among low-risk individuals, due to reduced secondary transmission. The analysis appeared to suggest that with a high-risk exclusive vaccination program, 75% efficacy and lifetime protection, the cost-savings in healthcare expenditures would approximate $31 billion.

Targeted vaccination of high-risk groups appears by far more efficient than universal vaccinations. However the authors suggest that should an effective vaccine be developed, a universal vaccine strategy should still be utilized in order to ensure most, if not all, high-risk individuals participate. As the authors only appear to take into account the cost analysis of the hypothetical 20 year period, they fail to address the costs, towards vaccine research, accrued over the previous 20+ years, as well as the costs to amount over the next indefinite number of years until full vaccine development. While I cannot speak to the cost-benefit versus sunken-costs of this research over the last 20 years, the increase in life expectancy of those HIV positive in the U.S., and the reduced transmission rate appear to be significant enough to continue research in vaccine developments.

Long, E.F., M.L Brandeau, D.K. Owens. 2009. Potential population health outcomes and expenditures of HIV vaccination strategies in the United States. Vaccine 27:5402—5410.

Wednesday, October 21, 2009

Google: saving the world one internet-junkie at a time

According to Marcia Stone, for Microbe Magazine, has donated over $10 million within the last calendar year toward “Infectious Disease Surveillance Efforts.”

My favourite, and the most accessible to the general public, was a $3 million grant to the International Society for Infectious Disease ProMED-mail (Program for Monitoring Emerging Diseases) program back in January 2009. The purpose of this financial award was to help strengthen the ProMED/HealthMap partnership. HealthMap is a digital surveillance program out of Harvard Medical School and Children’s Hospital Boston. HealthMap takes information from ProMED regarding emerging infectious disease outbreaks, and produces global [web] maps depicting the outbreaks geographically. The hope is to eventually identify and respond to the outbreak of a novel pathogen and prevent the regional outbreak from becoming a global pandemic. One downside to the current website is that it only displays reported cases, thus leaving the numbers of cases depicted strongly biased. An important goal in utilizing these funds is to expand and develop networks in Africa and Southeast Asia.