The global food crisis, climate change, and pandemic influenza are the main threats to human health listed by WHO. Although 30% of all deaths are caused by infectious diseases, chronic conditions such as heart disease and stroke kill more people than infectious diseases do for the first time in history because people are living longer. However, mutations in avian flu or other communicable diseases could change this. Over the past 40 years, 39 new infectious diseases have been discovered, more than 1,100 epidemics have been verified in the last five years, and we face 20 drug-resistant diseases today. Old diseases have reappeared, such as cholera, yellow fever, plague, dengue fever, meningitis, hemorrhagic fever, and diphtheria. Massive urbanization and concentrated livestock production could trigger new global pandemics. Climate change is altering insect and disease patterns. Halfway to 2015, most health-related MDGs (reduce child mortality; improve maternal health; and combat HIV/AIDS, malaria, and other diseases) are unlikely to be met. Other problems may come from synthetic bacteria from gene laboratories and unknown nano-organisms.

To prevent bioterrorism, R&D has increased for improved bio-sensors and general vaccines able to boost the immune system to contain any deadly infection. Such vaccines could be placed around the world like fire extinguishers. The 4-million-person shortage of health workers is growing, people are living longer, and health care costs are increasing—all making tele-medicine, self-diagnosis via biochip sensors, and online expert systems increasingly necessary. In the meantime, the best ways to address infectious diseases are early detection, accurate reporting, prompt isolation, transparency of information, rapid diagnostics, appropriate treatment, and growing global awareness.

Meanwhile, the world is preparing for potential genetic variations in the H5N1 avian flu virus that could be highly contagious among humans, killing tens of millions. A two-dose vaccine has shown positive effects against H5N1. A new approach to Asian poultry live-market businesses—the source of such viruses—is needed

Although hepatitis B is the most common infectious disease, with more than 2 billion people currently or previously infected, and although malaria kills over 1 million a year, HIV/AIDS is still the largest killer in sub-Saharan Africa and its impact continues to grow in Eastern Europe and Asia. Estimates of those living with HIV/AIDS have substantially decreased from 34.1–47.1 million in 2006 to 30.6–36.1 million in 2007 due to recent advances in the research methodology of HIV statistics, natural trends in the epidemic, and prevention programs. The number of new cases of HIV probably peaked in the late 1990s at over 3 million per year and had fallen to 2.5 million by 2007. Deaths from AIDS dropped from 2.9 million in 2006 to 2.1 million in 2007. Some 31% of the estimated 9.7 million people in need of receiving antiretroviral therapy received it by the end of 2007.

Two broad patterns in HIV/AIDS are emerging: generalized epidemics in sub-Saharan Africa and more local epidemics in the rest of the world concentrated among populations at risk: men who have sex with men, injecting drug users, and sex workers and their sexual partners. The costs of antiretroviral drugs were reduced by 20% to developing countries during 2007 by Glaxo. The Clinton Foundation continues to reduce costs of second-line drugs in some areas to $100/year and the daily one-pill to $1/day. Self-tests for AIDS cost $15, and the $40 for confirmatory results continues to decrease. For every person who starts taking antiretroviral drugs, another 2.5 become infected, down from 5 about two years ago. No significant positive vaccine results are yet available, but new genetic-based vaccines and microbicides are in trial, and pre-exposure treatment and radioactive anti-HIV antibodies show promise in animal models. Male circumcision may reduce infection by 50%.

WHO’s eHealth systems, new regulations to address SARS-like threats, immunization programs, and the Global Outbreak Alert and Response Network are global responses to this challenge. Scientists are working to develop a genetically modified mosquito that would not carry the malaria parasite. Better trade security will be necessary to prevent increased food- or animal-borne disease. Viral incidence in animals is being mapped in Africa, China, and South Asia to divert epidemics before they reach humans. Future uses of genetic data, software, and nanotechnology will detect and treat disease at the genetic or molecular level. Meanwhile, increased investment into water, sanitation, health education, and hand washing is the most cost-effective way to reduce communicable disease.

North America: Genetics-based and molecular research in North America will affect prevention, diagnosis, and treatment of a large number of diseases. Over a million people in the U.S. and 62,000 in Canada were HIV-positive at the beginning of 2007. Antiretroviral medications keep AIDS death rates low. Increased food imports raise vulnerability to infections from overseas.

Graph: Physician density (per 10,000 population)

Source: World Health Organization, Core Health Indicators