The various investments in the healthcare system since SUS was formed, plus better access to clean water and sewerage systems, have fuelled major progress in reducing the burden of infectious diseases. In the third paper, Professor Mauricio L Barreto, Instituto de Saúde Coletiva and Federal University of Bahia, Salvador-Bahia, Brazil, and colleagues look at why some programmes have worked and others have not.
Control of diseases such as cholera, diarrhoea, Chagas disease, and those preventable by vaccination such as tetanus and polio have all been successful, having each provided universal treatment free at the point of vaccination. These policies need to be reinforced due to challenges such as increasing prevalence and transmission of drug resistance.
A partly successful programme is the HIV/AIDS plan, which is the largest distributor of free antiretrovirals in the world. Many feared drug resistance would emerge rapidly but it has only done so at the rate common in high-income countries. Some 600,000 people have HIV, with a population prevalence of less than 0.6%: estimates that have been stable since the beginning of the Millennium. Men who have sex with men, sex workers and injecting drug users (IDUs) are at the highest risk. Despite this, infection prevalence in IDUs has come down to 8% from its level of 25% in the mid-1990s. Programmes aiming to prevent mother-to-child transmission, and public health campaigns highlighting safe sex messages and the need to seek prompt treatment if infection is suspected have contributed to Brazil's overall good record in HIV/AIDS. Tuberculosis control has also improved, partly due to increased HIV control and also specific roll out of antibiotic programmes and those offering directly supervised treatment.
Failures are few but need to be noted. Dengue fever is a major public health problem, with some 3.5 million cases reported in the past decade, with 12000 leading to the more serious dengue haemorrhagic fever, and some 900 deaths. Rates of the most serious disease are six times what they were in the 1990s. No safe vaccine is available and none is likely to emerge for years. Dengue has a changing epidemiological profile and treatment is unavailable. Even with half a billion US dollars invested in vector control to combat the A aegypti mosquitoes that carry the disease, few inroads have been made. Visceral leishmaniasis control is also poor, with current efforts focusing on vector control of the sandfly carriers and removing domestic animals that can act as reservoirs. Treatment is highly toxic and while accessible and suitable in urban areas with medical support, this toxicity makes treatment in remote rural areas inappropriate.
The authors conclude: "A pressing need exists to develop new treatments and vaccines for those diseases which have proved difficult to control. In Brazil, biomedical and epidemiological research is thriving, as is public health research into infectious diseases, with much collaboration with developing and developed countries...the fast growth in medical research must be sustained—efforts must go towards identification of new treatments (eg, for leishmaniasis) new vaccines (eg, for dengue) and more effective ways to deliver specific care."
Professor Mauricio L Barreto, Instituto de Saúde Coletiva and Federal University of Bahia, Salvador-Bahia, Brazil. T) +55 71 3283-7445/7452 E) Mauricio@ufba.br
Journal
The Lancet