| Objectives To analyze the epidemiological characteristics ,clinical manifestation and laboratory examination of meningococcal disease in Hefei City,and to provide the basis for clinical diagnosis and treatment. To establish a forcasting GM(1 ,1) grey model and estimate its application value for forecasting the epidemic situation of meningococcal meningitis in Hefei City.To analysis the association with the meningococcal disease and climate factors and provide basis for prevention and control measures.Methods Adopted description epidemiological method to analyze the data of the patients with meningococcal disease in Hefei City during 2003 to 2007. According to the meningococcal meningitis incidence of Hefei City from 2002 to 2006, a forecasting model of meningococcal meningitis incidence was built, and the trend of the incidence of meningococcal meningitis in 2007 was forecasted in order to evaluate the effect of prevention and treatment.The incidence of meningococcal disease from 2003 to 2007 in Hefei City was analyzed by descriptive study method. Analysis of association between incidence of meningococcal disease and meteorological factors, including temperature, rainfall, sunshine time, relative humidity was done by relative correlation and multiple stepwise regression analysis.Results1. Totally , during 2003 to 2007 ,the cases of Meningococcal Disease in Hefei City were 394;the average annual incident rate was 1.70 per 100,000 and the top incidence rate existed in 2007(2.84 per 100,000).The N. meningitidis serogroup was identified in 130 cases (33.0%) of the Meningococcal disease cases—all in serogroup C.The median age of these patients was 14.32 years (age ranged from 2 months to 78 years).The highest incidence rate (6.04 per 100,000 population) and the highest proportion (29.11%) of cases occurred in aged 15-19 years old. 50.80% of all the cases are students,and also the proportion of the student cases increased year by year,in 2007,it came to be 57.58%.Nineteen(56 cases)clusters were identified,among which 8 clusters occurred in schools(4 clusters were from vocational school).All the cluster cases were caused by serogroup C.2. The symptoms appearance firstly of patients are fever, dizziness and vomiting simultaneously, fever and dizziness simultaneously, and fever alone, which accounted for 23.6%, 12.4% and 10.9% respectively. Patients treated firstly in private diagnostic clinic, in the township hospitals, in the county-level medical care, in city-level medical institutions the provincial-level medical institutions accounted for 11.2%,3.8%,17.5%, 29.9% and 36.3% respectively.There were significant difference in different level of hospitals between the outbreaks and sporadic cases(P<0.05).Popular type , fulminating type and light type are accounting for 79.66 %,19.31%and 1.03% respectively in all cases, while popular type, fulminating type and light type accounted for 79.66%,19.31% and 1.03% respectively in patients of serogroup C .There were no significant difference among clinical classification between serogroup C and all cases(P>0.05).The major clinical symptoms are fever, vomiting, nausea, neck stiffness, severe headache, petechia and consciousness unclear, which account more than 50%.There were significant difference in Brudzinski's signs between cases confirmed serogroup C and all cases(P<0.05).3. Eight cases had WBC count in blood routine low to normal value, among which there are 2 cases of serogroup C, and 15 cases had blood neutrophil count dropped to normal level, among which there are 3 cases confirmed serogroup C; Blood neutrophil count of two cases drop to normal level in all death cases.4. The mathematical model was established as Yt = 0. 49927e0 .556t-0.40827,and the estimation test results of model are C =0.2931 and P = 1.00, indicating that the model was well fitted with the meningococcal meningitis incidence changing curve from 2002 to 2006.Based on the model , the predicted malaria incidence was 5.985/ 100000 in Hefei City in 2007. However , the actual incidence was 2.840/ 100 000 ,decreased by 210.8 % compared with the predicted value.5. The results showed that meningococcal disease was negative relative to temperature, relative humidity. Regression equation Y = 50.005-0.392 x1-0.516 x4 (x1 = temperature, x4=relative humidity) was obtained by multiple stepwise regression analysis.Conclusions serogroup C replaced serogroup A as the most predominant serogroup and by which the incidence of meningococcal disease substantially increased in Hefei City, and changes in the age distribution of the cases that from younger to older-age categories were also observed. Further investigation and surveillance of meningococcal disease is still necessary. Cases of serogroup C in the symptoms appearance firstly, the clinical classification, clinical performance found not serious than in all cases; blood WBC count and neutrophil count low to normal level emerged in cases, it is worth our attention. The GM(1 ,1) grey model may be useful for forecasting meningococcal meningitis prevalence trend in in Hefei City. The increase of the observed meningococcal meningitis incidence in 2007 compared with the predicted value indicated that Hefei City achieves obvious effect in meningococcal meningitis prevention and control. Temperature and relative humidity become two main factors affecting the incidence of the meningococcal diseases. Meteorological factors may play a role in the forecast of incidence of meningococcal disease.
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