Its primary effect is to decrease the number of white blood cells, causing the disease known as feline panleukopenia.

Thus the word means depletion of multiple types of white blood cells (leuckocytes, including neutrophils, lymphocytes, thrombocytes).

[13] Antibodies against FPLV, produced by the adaptive immune system, play an important role in the feline response to the virus.

[14] In kittens, the period of greatest susceptibility to infection is when maternal antibodies are absent, or waning, and vaccine-induced immunity has not yet fully developed.

Those that develop a subclinical infection or survive acute illness mount a robust, long-lasting, protective immune response.

[6] An infected cat sheds large amounts of virus in all body secretions including feces, vomit, urine, saliva, and mucus during the acute phase of illness.

The virus can be carried or transferred on an infected object (such as bedding, food dishes, fur) or by other animals, fleas, and humans (see: fomites).

[17] Kitten deaths have been reported in households of fully vaccinated cats, possibly because of exposure to large amounts of virus in the environment.

[13] The clinical manifestations of FPLV are variable based on the dose of the virus, the age of the cat, potential breed predispositions, and prior immunity from maternal antibodies, previous exposure, or vaccination.

[20] Most infections are subclinical, as evidenced by the high seroprevalence of anti-FPV antibodies among some populations of unvaccinated, healthy cats.

[22] The virus infects and destroys actively dividing cells in bone marrow, lymphoid tissues, intestinal epithelium, and—in very young animals—in the cerebellum and retina.

[6] The virus primarily attacks the lining of the gastrointestinal tract, causing internal ulceration and, ultimately, total sloughing of the intestinal epithelium.

PCR assays are so sensitive that FPV DNA can be amplified from feces of cats vaccinated with modified live strains of the virus.

Elevated IgM titers (1:10 or greater) indicate active infection and if clinical signs are obvious (diarrhea, panleukopenia) the prognosis is poor.

[30] In a disease outbreak, unvaccinated kittens or adults can be given anti-FPV serum containing FPV antibodies injected subcutaneously or intraperitoneal.

[29] Several studies have shown recombinant feline interferon omega is effective in the treatment of parvoviral enteritis in dogs[36][37] and also inhibits replication of FPV in cell culture.

Cats typically die due to complications associated with sepsis, dehydration, and disseminated intravascular coagulopathy (DIC).

[42] Strict protocols for containment – with isolation, minimal handling, and disinfection of all potential sources of fomites – is warranted.

These recommendations take into account considerations for the efficacy and longevity of each specific vaccine; the exposure, risk, and need of different cat populations; and socioeconomic limitations.