tailieunhanh - Human Virology_2

Tham khảo sách 'human virology_2', y tế - sức khoẻ, y học thường thức phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | HV3E_16 127-136 5 5 06 5 47 PM Page 127 Chapter 16 Poliomyelitis and other picornavirus infections 1 Properties of the viruses 127 Classification 127 Morphology 129 Genome and polypeptides 129 Replication 129 2 Clinical and pathological aspects 129 Poliomyelitis 129 Infections caused by enteroviruses other than polioviruses 132 Laboratory diagnosis 135 3 Control measures 136 4 Reminders 136 The family Picornaviridae is one of the largest in numerical terms to be considered in this book and contains some of the smallest viruses of which poliovirus is the most important. Poliomyelitis was one of the first diseases to be recorded an Egyptian tomb carving of the Nineteenth Dynasty shows the dead man to have had a foot-drop deformity typical of paralytic poliomyelitis Fig. . A world polio eradication campaign should result in this virus becoming extinct by 2006. The extraordinarily wide range of diseases caused by different members of the family is summarized in Table . The syndromes include asymptomatic infection which fortunately is by far the most common disease of the CNS febrile illness with rash conjunctivitis herpangina infections involving the muscles and heart and hepatitis. Probably no other family of viruses causes such a diversity of illnesses. 1 Properties of the viruses Classification The family Picornaviridae contains six genera Table . Its name derives from the small size of these viruses pico small and their RNA genome. Picornaviruses are found in several mammalian species but we shall describe only those that infect humans. They are acid-resistant which enables them to survive passage through the stomach. They replicate in the small intestine can readily be isolated from faeces and are spread by the faecal-oral route. Gastroenteritis is however not a major feature of picornavirus infections. Poliovirus was the first of the genus indeed of the whole family to be isolated. This accomplishment by Enders Weller