WHO has had less success overcoming infectious diseases for which there are no effective vaccines, particularly malaria, tuberculosis, and HIV. The WHO goals for these diseases -- halve the global burden of malaria and tuberculosis and cut the number of new HIV infections by a quarter by 2010 -- are more modest than those for vaccine-preventable diseases. The goals probably reflect a realistic assessment of the difficulty of combating diseases when what is required is the interruption of insect carriers (malaria), an improvement in living conditions (tuberculosis), or a change in social behavior (HIV). WHO has called for the development of innovative strategies to deal with these still-rampant diseases, and continues to fund research into developing effective vaccines.
The recent outbreak of sudden acute respiratory syndrome (SARS) highlights WHO's strengths and weaknesses as a central body working to overcome disease. This new disease originated in China but spread quickly to other Asian countries and to Canada, aided by global air travel. WHO-employed and -affiliated epidemiologists were able to mobilize from regional offices and track the spread of the disease; in many areas, they were successful in mapping the spread of the disease from a single carrier. But because they have no legal authority to force nations to allow them to work inside their borders, scientists had to wait until the Chinese government relented and let them into the country before they could assess the extent of infection in that huge nation and identify the first known case of SARS.
WHO also monitors the global incidence of a wide range of diseases and provides advisories for travelers, recommending which inoculations and other preventive measures they need when traveling to particular areas.