Demonstration of four entities of appendicitis in China through studying cluster/outbreak

ObjectiveTo differentiate different entities of appendicitis through studying cluster/outbreak, ascertain common setting of cluster/outbreak, and provide the epidemiological evidences of infectious etiology of appendicitis. BackgroundDifferential diagnosis and management for perforated appendicitis and non-perforated appendicitis and the infectious etiology of appendicitis are current hot topics. MethodsField investigation for Tibetan students were carried out and reports published in English and Chinese medical journals were reviewed. ResultsThe literature review included 473 patients in 7 cluster/outbreaks of appendicitis in 6 provinces and autonomous regions. All the clusters/outbreaks occurred in group living units. We found two classic entities of appendicitis with natural history from non-perforated appendicitis to perforated appendicitis and two entities of non-perforated appendicitis. In classic entities, one may represent majority of sporadic patients and the other may represent partial sporadic patients with obvious gastrointestinal manifestation. In entities of non-perforated appendicitis, one was identical to features of sporadic non-perforated appendicitis and the other one is identical to the following Tibetan students and associated with Fusobacterium. The field investigation for 120 Tibetan students with appendicitis showed that the resected appendices exhibited diffuse or focal hemorrhages and infiltration by eosinophils and by lymphocytes. Most patients had normal body temperature, white blood cell count and neutrophil count. This is a new entity of appendicitis. The clusters/outbreaks of appendicitis showed the features of infectious disease in epidemiology. The entity of perforated appendicitis was not found. ConclusionStudying cluster/outbreak is a good method to differentiate different entities of appendicitis and infectious etiology.