Viruses are the smallest and simplest elements which have the characteristics of a living organism. And yet they are one of the major causes of illness and mortality worldwide. The discipline of medical virology is a relatively young one, but enormous strides have been achieved in controlling many of the feared plagues of yesteryear. Smallpox virus one of the most feared of contagious diseases which “has killed more human beings in the civilised era than any other known human pathogen” [McFadden G, PLoS Pathogens (2010) 6: 1-4] was finally eradicated in 1979 by the first human vaccine – one of the foremost triumphs of 20th-century public health. And now, poliomyelitis, another of the dreaded contagions of yesteryear is targeted for eradication by 2018; already the majority of the world’s population live in countries which have been declared polio free.
Vaccines have played an enormously beneficial role in drastically reducing many human viral diseases, for example, measles and rubella (German measles)have now been eliminated from the Western Hemisphere and have been virtually eliminated from the developed world. Vaccines are also playing a major role in reducing two of the most important virus- induced cancers in Africa – cancer of the cervix by the human papilloma virus vaccine (HPV) and cancer of the liver by the hepatitis B vaccine.Formidably virulent viral diseases now and then present themselves, especially on the African continent, such as the viral haemorrhagic diseases caused by Ebola currently responsible for a major humanitarian disaster in West Africa and health authorities remain alert to the potential of non-human influenza viruses such as the H5N1 and H7N9 influenza viruses to cause pandemics in humans with possibly devastating consequences.
Human viral diseases present scientists with many ongoing challenges. One of the foremost of these is the elusive attempts so far to develop a preventive vaccine against HIV infection. Nevertheless a vast amount of knowledge has accumulated on the nature of the HIV virus and the host response to the infection and the disease it causes. This knowledge has been used with enormous success in the development of antiretroviral drugs which can now convert what was previously and inexorably fatal illness into a chronic manageable disease.
The story of man’s contest with his virus foes has produced many triumphs and gratifying successes. However numerous challenges remain and novel ones will eventuate as new viruses are detected on almost annual basis.