Mathematical modelling of parasite transmission systems can provide useful information about host parasite interactions and biology and parasite population dynamics. In addition good predictive models may assist in designing control programmes to reduce the burden of human and animal disease. Model building is only the first part of the process. These models then need to be confronted with data to obtain parameter estimates and the accuracy of these estimates has to be evaluated. Estimation of parasite densities is central to this. Parasite density estimates can include the proportion of hosts infected with parasites (prevalence) or estimates of the parasite biomass within the host population (abundance or intensity estimates). Parasite density estimation is often complicated by highly aggregated distributions of parasites within the hosts. This causes additional challenges when calculating transmission parameters. Using Echinococcus spp. as a model organism, this manuscript gives a brief overview of the types of descriptors of parasite densities, how to estimate them and on the use of these estimates in a transmission model.
Mathematical modeling ya mifumo ya maambukizi ya vimelea inaweza kutoa habari muhimu kuhusu mwingiliano wa vimelea mwenyeji na biolojia na vimelea idadi ya nguvu. Kwa kuongezea, mifano nzuri ya utabiri inaweza kusaidia katika kubuni programu za udhibiti ili kupunguza mzigo wa magonjwa ya binadamu na wanyama. Kujenga mfano ni sehemu ya kwanza tu ya mchakato huo. Mifano hizi kisha zinahitaji kukabiliana na data kupata makadirio ya parameter na usahihi wa makadirio haya lazima kupimwa. Makadirio ya wiani wa vimelea ni muhimu kwa hili. Makadirio ya wiani wa vimelea yanaweza kujumuisha uwiano wa majeshi yaliyoambukizwa na vimelea (kuenea) au makadirio ya biomass ya vimelea ndani ya idadi ya majeshi (makadirio ya wingi au nguvu). Makadirio ya wiani wa vimelea mara nyingi ni ngumu na usambazaji wa jumla wa vimelea ndani ya majeshi. Hii husababisha changamoto za ziada wakati wa kuhesabu vigezo vya usafirishaji. Kwa kutumia Echinococcus spp. Kwa mfano, kitabu hiki kinatoa muhtasari mfupi wa aina za descriptors ya wiani wa vimelea, jinsi ya kukadiria yao, na jinsi ya kutumia makadirio haya katika mfano wa maambukizi.