May 1, 2021 · Persistently infected (PI) calves are one of the greatest threats facing the cattle industry, but many producers don’t even know they’re in the herd.

Persistently infected calves acquire BVDV in utero during gestation. Infection of the calf in utero is the only way to become a PI animal. If a cow is infected at the time of fertilization, conception rates may be decreased.

Although the pregnant cow is negative, she may be carrying a persistently infected (“PI”) calf that will test positive. Most PIs are born to heifers who were naïve (poorly vaccinated) at the time of BVD infection.

PI heifers and cows always produce PI calves. Most PI calves are the result of transient BVD infections of their dams during pregnancy. Transiently infected cattle shed relatively low quantities of virus for 7 to 14 days, but then clear the infection and stop shedding the virus.

Sep 22, 2022 · A PI calf is an animal that acquired bovine viral diarrhea virus (BVDV) from its mother during pregnancy. The PI calf appears clinically normal and can often go its whole life without showing visible signs, while still shedding BVDV …

Oct 18, 2023 · Although a pregnant cow tests negative for BVD, always bear in mind she can still be carrying a persistently infected (“PI”) calf that will test positive. Over 90% of PI calves are born from BVD negative dams.

For cattlemen, the primary concern of spreading the BVD virus is through PI cattle; with transiently (or temporarily) infected cattle considered a less important source of the disease. PI animals are very efficient transmitters of the virus.

Cattle persistently infected (PI) with bovine viral diarrhea virus, commonly known as BVDV, represent a low-prevalence but high-cost disease affecting all segments of the industry due to limited monitoring and lack of diagnosing PI animals.

Persistently infected (PI) cattle are infected while in the uterus. These animals are infected for life and are the primary source of new PI animals, as they continually shed large amounts of virus throughout the herd. Transiently infected (TI) animals are exposed to BVD after they are born.

PI stands for Persistently infected. PI cows are lifelong carriers of the BVD virus and shed hundreds of thousands of virus particles. Enough to overwhelm the immune system of animals they come into contact with (and even enough to overwhelm some vaccinated animals).