The Monitoring Of Hand Foot And Mouth Disease And The Characterisation And Pathogenesis Of Enterovirus 71

1. Background & ObjectivesHand, foot, and mouth disease (HFMD) is a common childhood exanthema.In most instances, this is a mild self-limiting illness. The affected children are often given out-patient care with symptomatic treatment. It is characterised by a brief prodromal fever, followed by pharyngitis, mouth ulcers and rash on the hands and feet. The disease is caused by numerous members of the Enterovirus genus of the family Picornaviridae such as Coxsackievirus type A (CA) and Enterovirus 71 (EV71), transmission occurs from person to person through direct contact with saliva, faeces, vesicular fluid or respiratory droplets of an infected person and indirectly by contaminated articles. However over the last decade HFMD has emerged as a growing public health problem in Asia following frequent outbreaks of death associated HFMD caused by a more virulence member of human enteric virus(HEV). In Singapore with the annual incidence rate per 100,000 population increased from 125.5 in 2001 to 435.9 in 2007. In china, HFMD is the most important fatal infection disease. HFMD has emerged as an important public health problem.Human enterovirus (EV71) was first described by Schimdit et al. in 1974, which belonging to Picornaviridea family and has a single positive stranded ribonucleic acid(RNA) of about 7,500 nucleotides. There have 13 large and small reported outbreaks of EV71 throughout the world since then, which main leads to high prevalence of hand, foot and mouth disease (HFMD) in infants and children under 6 years old. In past decades, countries in the Asia-Pacific region have experienced an increased occurrence of EV71 associated HMFD outbreak. Most of EV71 infections are benign and selflimited in nature, however, EV71 infection has been reported to cause neurological disease manifesting as aseptic meningitis, encephalitis or poliomyelitis-like acute flaccid paralysis, and neurological originated pulmonaryedema or hemorrhage were the main lethal symptoms. The central nervous system (CNS) injury dependent EV71 neuropathology is supposed as the main reason kills neuron and then lead to subsequent neurological destruction. However, the pathogenesis of EV71 infection, especially the CNS involvement, is not clearly understood. Little is known of the factors contributing to the manifestation of CNS symptoms. There are no effective vaccines and specific antiviral therapies available to control fatal outbreaks due in part to the lack of understanding of viral pathogenesisThe aims of the study were to demonstrate the properties of hand foot and mouth disease in a sentinel hospital of Guangzhou, and to designed to understand the characterisation and pathogenesis of enterovirus 71 using a autopsy tissues and the mouse model.2.Methods2.1. We reviewed the records of all cases of HFMD in a sentinel hospital from May 2008 to December 2009. Epidemiological data and clinical specimens were collected.2.2. Laboratory notifications of enteroviruses identified in stool samples, throat and rectal swabs and swabs from vesicular fluid randomly collected from inpatient cases of HFMD.Viral isolation, enteroviruses cultured, reverse transcriptase-PCR, molecular identification, and phylogenetic analysis were performed.2.3. Statistical analyses were performed using SPSS Software Version 13.0 (SPSS Chicago, IL). We used chisquare test for categorical data. A P value less than 0.05 was considered statistically significant.2.4. We reported a death case of an 8-mouth-old girl with EV71 infection,the clinicopathologic features and molecular studies were finished.Pathological features of systematic autopsy tissues was studied by hematoxylin and eosin staining.2.5. The distribution of EV71 antigen in the one case of full autopsy tissue samples from the patient with fatal HFMD were analyed by immunohistochemistry.2.6 Enterovirus 71 strains isolated from human clinical cases was used to cause paralysis by parenteral routes of inoculation in Balb/c suckling mice (7 days old). Pathological features and pathogenesis of enterovirus 71 were analyed.3. Results3.1. A total of 309 clinical cases were reported in 2008 and 154 cases in 2009, the incidence rate was highest in the 12 to 48 mouths old age group, sex differences and seasonality was existing, there was a male predominance of HFMD cases, with a male-to-female ratio 2.13. Seasonal variations in incidence were observed, with a peak in incidence during the summer season. Only 17 children developed complications.3.2. The predominant enterovirus was different in two years. The majority of the enteroviruses detected from the HFMD cases were EV71 in 2008, EV71:64.7% (134/207),CoxA16:14.5%(30/207), while both CoxA and EV71 were almost equally distributed in 2009, EV71:32.8%(40/122), CoxA16:45.1%(55/122)3.3. Phylogenetic analysis indicated that all 13 GuangZhou EV71 isolates belonged to Cluster C4a, basically same as the current epidemic genotype in mainland China and co-evolved with isolates from neighboring countries.3.4. Pathological features of EV71 infected case:The pulmonary fatal pathology was diffuse alveolar damage and necrosis, pulmonary hemorrhage. Pathological change of inflammation can see in mary organ and tissue,incluing kidney, heart, colon,hepatocyte hydropic degeneration. The central nervous system(CNS) showed a few of cells degeneration and necrosis,but the encephalitis was obvious than the change in cerebellum and brain stem.3.5. The distribution of EV71 viruses in the central nervous system tissues and organs:Immunohistochemistry showed positive monoclonal antibody against VP1 of EV71 in. gliocytes of cerebrum, granulosa cell of cerebellum, and nerve cell of brain stem.3.6 The animal model was successful with Balb/c suckling mice,the clinical manifestation including change of body weight, dispirited, chydermoperiostosis acroparalysis. EV71 was distributed in central nervous system both brain tissue and spinal cord, nerve cell degeneration was obvious.Pathological features showed pulmonary edema generated in earlier period.4. Conclusions4.1. HFMD is an important infection disease in Gaungzhou, A high degree of vigilance should be maintained over the disease situation, in particular, surveillance of EV 71 which continues to cause severe complications and deaths in the region.4.2. The predominant enterovirus was different in different years. Epidemic cycle mary occurs in Guangzhou.4.3. All EV71 strains isolated from GuangZho belonged to Cluster C4a and co-evolved with isolates from other provinces in China and neighboring countries.4.4. EV71 might cause a disseminated infection and multi-organ damages. Pathological change of lung was primary and predominant fatal reason.4.5. Gliocytes, granulosa cell and nerve cell of the central nervous system tissue were target cell of EV71.4.6. The Balb/c suckling mice is feasible animal model in EV71 infection,the nerve cell degeneration is major pathogenesis. Pulmonary edema should be alerted in earlier period.