Study On The Monitoring System Of Typhoid And Paratyphoid Fever In Hongta District, Yuxi City, Yunnan Province

Objective:1. According to the characteristic of Typhoid and paratyphoid, the fever surveillance system will be established and evaluated.2. Explore how the different referral models and definition of surveillance cases contribute to find typhoid and paratyphoid patients, then provide evidence for improving surveillance.Methods:Hongta district of Yuxi city in Yunnan province is selected as study area for the high prevalence of typhoid and paratyphoid. After investigating both the situation of disease surveillance system and the residents’ visiting behaviors for fever, fever surveillance system is established based on the allocation of health resources. The operation situation of fever surveillance system from May to December in 2008 is analysed, The situation of finding, reporting and diagnosing of typhoid and paratyphoid cases before the fever surveillance system established(2005 to 2007) are compared with that after system established(May to December in 2008), the core function and property of fever surveillance system are evaluated primarily.Results:1. Finding and reporting situation before fever surveillance system established (2005 to 2007) are compared with that after system established (May to December in 2008).(1) Fever surveillance system is established and carried out in 2008, May. The reported incidence rate is 100.79 per 100 thousand in 2008, which is lower than the average rate(221.18 per 100 thousand) from 2005 to 2007 (χ2=234.05, P<0.05)(2)The proportion of confirmed cases after fever surveillance system carried out is 56.52%, which is decreased by 15.71% compared with the average level (67.05%)from 2005 to 2007 (x2=12.38, P<0.05). The proportion of peasants in all cases is 39.16%, which is increased by 42.30% compared with the average level (27.52%)from 2005 to 2007 (x2=15.90,P<0.05).(3) The proportion of confirmed cases in fever surveillance system(99.64%),which is higher than that in normal infectious diseased network reporting system (79.56%) (χ2=61.12, P<0.05),beyond the average level (73.75%) from 2005 to 2007 (χ2=5.74, P<0.05).(4) There are only 31.91%(630/1974) cases from rural areas among all the reported typhoid and paratyphoid confirmed cases in Hongta district from 2005 to 2007. However, the cases from rural areas,which take up 58.31%, is increased by 82.73% (x2=103.10, P<0.05) after fever surveillance system carried out in 2008.(5) Blood culture positive rate of S.paratyphi A is 17.91% after fever surveillance system established, that is higher than the average rate (12.45%) in 2007.(6)The median of interval of typhoid and paratyphoid cases from onset of illness to confirmed is 5.67 days reporting by fever surveillance system after system established, that is reduced by 1.06 days compared with the average median of interval(6.73 days) from 2005 to 2007(Z=-3.78,P<0.05).2. Property evaluation of fever surveillance system(1) The accurate rate of system is 67.43%. The sentinel of type A is lowest(59.72%). The accurate rate of type B and C sites is 78.66% and 76.50% respectively.(2) There are 79.53% surveillance cases count leukocyte and 72.49% surveillancecases count eosnophils. The rate of leukocyte count and that of eosinophil count which are highest in type B sites are 91.75% and 88.92 respectively. The rate of leukocyte count and that of eosinophil count in type A sites are 71.88% and 60.98% respectively. Those rates in type C sites are 77.65% and 74.3% respectively.(3) There are 1113 surveillance cases in Hongta district, among which 1024 cases have whole blood sample. In other word, the whole blood sample rate is 92%. Sample rate of first visit cases reaches 94.75% in type A and type B sites.179 surveillance cases are referred in type C sites.87.71% cases are referred successfully in 48 hours, 77.65% referred cases are sampled.549 blood samples from type B sites are all sent to CDC of Hongta district in 48 hours. Both The timeliness rate and qualified rate are 100%.(4) Blood culture positive rate of S.paratyphi A is 20.42% in type A sites and is higher than that (12.93%)in type B and type C sites in which Blood samples are sent to CDC for test (χ2=10.41, P<0.05)(5) Blood culture positive rate of S.paratyphi A of cases according with the definition of surveillance cases is 16.41% and is higher than that not according with definition (8.17%) (x2=15.00, P<0.05). Meanwhile the rate is higher than that before surveillance system carried out(12.65%) in 2007 (x2=12.07, P<0.05)(6) Blood culture positive rate of S.paratyphi A is 15.36% in cases whose leukocyte count is normal or reduced. The rate is higher than cases whose leukocyte count is increased(7.32%) (x2=9.24, P<0.05). Blood culture positive rate of S.paratyphi A is 18.52% in cases whose eosinophil count is reduced or disappeared. The rate is higher than cases whose eosinophil count is normal or increased(7.36%) (χ2=28.19, P<0.05).If regard the result of blood culture test as gold standard, the sensitivity and specificity of leukocyte count are 91.98% and 16.07% respectively when diagnosing paratyphoid. Those of eosinophil count are 82.22% and 38.24% respectively.(7) All whole blood samples are tested in 24 hours after CDC received samples. 98.54% results are fed back and 98% are fed back in 24 hours.3. Severe situation of antibiotic abuse86.99% fever surveillance cases used antibiotic before visiting. Antibiotic abuse is very serious. It is showed that Blood culture positive rate of S.paratyphi A (14.07%) of cases who took antibiotic before visiting is lower than those never took antibiotic (26.27%) (χ2=11.58, P<0.05)Conclusion1. Fever surveillance system can be regarded as a useful supplement for normal epidemical surveillance report.2. The definition is reasonable.3. Referral, sample and test model is feasible.4. blood routine examination can help diagnose typhoid and paratyphoid.5. Antibiotic abuse do harm to diagnosis.6. The following work should be enforced:strengthen training, improve primary record and the surveillance quality of type A sites, pay attention to outbreak surveillance, increase the bacteria carrier detection rate after illness.