应用罗斯疟疾微分方程分析海南省微小按蚊分布地区疟疾流行潜势的初步研究

APPLICATON OF ROSS'S MALARIA DIFFERENTIAL EQUATION FOR ANALYSING MALARIA EPIDEMIC POTENTIAL IN HAINAN PROVINCE

当前南岛在越来越多的地方重新发现一度绝迹的主要传疟媒介微小按蚊,而且由微小按蚊引起局灶性疟暴发时有发生。

Ross's differential equation dy/dt=cy(1-y)-ry express briefly the course of malaria endemic under differen conditions. Its positive balance solution, (?)=1-r/c, i, e. equilibrium prevalence of malaria reflects the variant malaria endemicity.The level of (?) is based on c (contact rate or vectorial capacity) and r(recovery rate). The vectorial capacity(c=ma^2 b(?)~2/-lnP) was investigated and estitnated in Feibar district of Danxian County where A. minimus is transmiting vector. In the residential quarer of local people rearing more cattle and having better socio-economic conditions the vectorial capacity of A. minirnus was 0.07, but it was 0.38 in another residential quarter of reclamation of outcomer with few cattle reared and poor socio-economic conditions. According to treat malaria cases in time or not, the recovery rate(r)is supposed to be 0.33 and 0.067 respectively(corresponding respectively giving 3 days and 15 days of interval between attack and treatment). Then the equilibrium prevalence y may be get 4 different level e.g. 0, 4.3％, 13.1% and 82.4％ respectively. This is closely resemble to 4 different types of endemic level in local conditions, such as the parasite rate was zero in residential quarters of state-run farm, 2.91％ in residential quarters of local Peasants, 20.0% in residential quarters of reclamation of outcomer, and over 50.0% in some spots outbreak. It is suggested that estimating equilibrium prevalence from vectorial capacity for analysing the epidemic potential of malaria may be a useful method of transmission dynamics.