Eight species of Eimeria and 1 of Isospora infect pigs in the North America. Piglets 5–15 days old are characteristically infected with only I suis,
which produces enteritis and diarrhea. These agents must be
differentiated from viruses, bacteria, and helminths that also cause
scours in neonatal pigs.
I suis is prevalent in neonatal pigs.
Infection is characterized by a watery or greasy diarrhea, usually
yellowish to white and foul smelling. Piglets may appear weak,
dehydrated, and undersized; weight gains are depressed, and sometimes
piglets die. A contributing factor to mortality is that piglets become
covered with diarrheic feces and stay damp.
Oocysts are usually shed in
the feces and can be identified by their size, shape, and sporulation
characteristics; however, in peracute infections, diagnosis must be
based on finding stages of the parasite in impression smears or
histologic sections of the small intestine because pigs can die before
oocysts are formed. In severely affected piglets, histologic lesions
confined to the jejunum and ileum are characterized by villous atrophy,
blunting of villi, focal ulceration, and fibrinonecrotic enteritis with
parasite stages in epithelial cells.
Preventive control by feeding anticoccidials to sows
from 2 wk before farrowing through lactation or to neonatal pigs from
birth to weaning has been reported; however, effectiveness of the latter
has not been confirmed. Although the sow is a logical source of
infection for piglets, this has not been well documented. Thorough
removal of feces and disinfection of farrowing facilities between
litters greatly decreases infection. Piglets that recover from infection
are highly resistant to reinfection.
Although less commonly associated with clinical coccidiosis, E debliecki, E neodebliecki, E scabra, and E spinosa have been found in pigs ~1–3 mo old with diarrhea. Illness may last 7–10 days, with pigs remaining unthrifty.
Treatment of coccidiosis may include sulfamethazine in
drinking water. The control of coccidiosis in newborn piglets infected
with I suis has been unreliable. The
use of coccidiostats in the feed of the sow for several days or a few
weeks before and after farrowing has been recommended and used in the
field, but the results are variable. Amprolium and monensin are
ineffective for the prevention of experimental coccidiosis in piglets. A
control program designed to decrease the number of oocysts has been
recommended and consists of proper cleaning, disinfection, and steam
cleaning of the farrowing housing. Amprolium (25% feed grade) at the
rate of 10 kg/tonne of sows' feed started 1 wk before farrowing and
continued until the piglets are 3 wk of age has been recommended, but
the results are unsatisfactory. A single dose of toltrazuril (20 mg/kg,
PO) decreased oocyst excretion, the incidence of diarrhea, and weight
gain impairment in piglets with experimentally induced coccidiosis.
Diclazuril (5 mg/kg) is being investigated as an oral anticoccidial in
piglets.