9 research outputs found
Detection of Babesia divergens in southern Norway by using an immunofluorescence antibody test in cow sera
<p>Abstract</p> <p>Background</p> <p>The incidence of bovine babesiosis, caused by <it>Babesia divergens </it>(Apicomplexa: Piroplasmida) has decreased markedly since the 1930 s, but may re-emerge as a consequence of climate change and changes in legislation and pasturing practices. This is a potentially serious disease, with both economical and animal welfare consequences. Therefore, there is a need to survey the distribution of <it>B. divergens</it>.</p> <p>Methods</p> <p>We tested sera from 306 healthy pastured cows from 24 farms along the southern Norwegian coast by using an indirect immunofluorescence IgG antibody test (IFAT). Fractions of seropositive cows were compared by calculating 95% CI.</p> <p>Results</p> <p>The results of this test showed that 27% of the sera were positive for <it>B. divergens </it>antibodies. The fraction of antibody-positive sera that we detected showed a two-humped distribution, with a high fraction of positives being found in municipalities in the western and eastern parts of the study area, while the municipalities between these areas had few or no positive serum samples.</p> <p>Conclusions</p> <p>Neither the farmers' observations nor the Norwegian Dairy Herd Recording System give an adequate picture of the distribution of bovine babesiosis. Serological testing of cows by using IFAT is a convenient way of screening for the presence of <it>B. divergens </it>in an area.</p
Cancer recurrence times from a branching process model
As cancer advances, cells often spread from the primary tumor to other parts
of the body and form metastases. This is the main cause of cancer related
mortality. Here we investigate a conceptually simple model of metastasis
formation where metastatic lesions are initiated at a rate which depends on the
size of the primary tumor. The evolution of each metastasis is described as an
independent branching process. We assume that the primary tumor is resected at
a given size and study the earliest time at which any metastasis reaches a
minimal detectable size. The parameters of our model are estimated
independently for breast, colorectal, headneck, lung and prostate cancers. We
use these estimates to compare predictions from our model with values reported
in clinical literature. For some cancer types, we find a remarkably wide range
of resection sizes such that metastases are very likely to be present, but none
of them are detectable. Our model predicts that only very early resections can
prevent recurrence, and that small delays in the time of surgery can
significantly increase the recurrence probability.Comment: 26 pages, 9 figures, 4 table