Clinical characteristics and epidemiology of novel bunyavirus human infection cases in Dandong city,2010-2012

Objective To analyze the clinical features and epidemiological characteristics of human infection of novel bunyavirus and to provide evidences for making prevention and control measures.Methods Case study was conducted with uniform diagnostic criteria and questionnaire survey.Results From 2010 to 2012,a total of 52 cases of novel bunyavirus infection were confirmed in Dandong city,with an average annual incidence rate of 2.16/100 000 and a fatality rate of 7.69%.The main clinical manifestations of the cases were fever(100%),body pain(82.7%),headache(75%),fatigue(71.2%),and nausea(76.9%).The blood examinations showed a reduced platelet counts(98.1%)and a decreased white blood cell count(92.3%).Of the cases 71.2% showed symptoms of a cold.A great number of cases came from the mountainous and hilly areas and the majority of the cases were male,elderly persons,farmers,with the onset time from June to October.A clear history of tick bite before the onset was reported by 48.1% of the cases.A secondary case was the sister of a confirmed male case and had a hsitory of blood contact.ConclusionThe initial clinical symptoms of novel bunyarirus infection are cold and atypical symptoms and the incidence of the infection presents obvious geographical characteristics,with sporadic cases.Animal and tick vector play an important role in human bunyavirus infection but human to human transmission of the virus could not be ruled out.