Viral gastroenteritis It is thought that viruses are responsible for up to 3/4 of all infective diarrhoeas Viral gastroenteritis is the second most common viral illness after upper respiratory tract infection

Genera of picornaviruses Enterovirus Polio Diseases of the human (and other alimentary tract Coxsackie a and B (e.g. polio virus

Categories of Respiratory Viruses Orthomyxoviridae: Influenza virus Paramyxoviridae: Parainfluenza virus, Mumps virus; Measles, Respiratory syneytical virus Togaviridae: Rubella virus Coronaviridae: corona irus, sars virus Adenoviridae: human Adenovirus picornaviridae: Rhino virus;

Category of sample Blood, Urine, Stool, nasal washing, nasal swab, throat swab, saliva, sputum, rectal swab, vesicle fluid scraping or swab) tissue, brain biopsy, cerebrospinal fluid, et

What does a pathogen have to do? Infect (infest) a host Reproduce(replicate) itself Ensure that its progeny are transmitted to another host

Medical Virology Dept. of Medical Microbiology and Parasitology Shanghai Second Medical University Shanghai, China. E.mail:(xkguoshsmu.edu.cn)

Spirochetes Gram negative Long, thin, helical, motile axial filaments locomotion between peptidoglycan layer/outer membrane runs parallel

Biological Features Structure and chemical composition Developmental cycle Staining properties Antigens Growth and metabolism Characteristics of host-parasite- relationship Classification

Mycoplasmas a group of the smallest organisms that can be free living in nature, Pass bacterial filter and also grow on laboratory media. More than 80 species, belong to Mycoplasmatales of mollicute. 3 families can be divided:

Campylobacter Among the most widespread cause of infection in the world Cause both diarrheal and systemic diseases Campylobacter jejuni