Nature of the disease
Coccidiosis continues to be one of the
disease problems for cattle producers. It is caused by
microscopic, one-celled parasites, chiefly of the genus
Eimeria. Twenty-one species of Eimeria have been reported in
cattle. Only two, Eimeria bovis and Eimeria zuernii, are
regularly associated with clinical infections in the field.
The disease is seen more commonly in calves
six to nine months of age but it may occur in yearlings and
Coccidiosis occurs most commonly in animals
housed or confined in small areas contaminated with oocysts.
Coccidiosis usually is sporadic during the wet seasons of the
year, but may develop any time cattle are crowded together as
animals confined in feedlots or calves brought together for
weaning or crowding around a limited water source, which
concentrates the hosts and parasites within a restricted area
that may cause severe losses. Outbreaks usually occur within
the first month of confinement.
The immunosuppressive effect of various
stressors such as weaning and change of feed or severe weather
or overcrowding and poor sanitation is important in
precipitating clinical disease.
Coccidiosis can cause significant economic
losses in cattle. Although most cattle are exposed to coccidia
and infected, most of the infections are self-limiting and
mild or asymptomatic. Economic losses from Coccidiosis may
include weight loss with possible death in acute cases and
growth retardation in the chronic form that may act as a
stressor causing an increased susceptibility to other
infections such as salmonellosis or Bovine Respiratory
Bovine Coccidiosis is caused by unicellular
protozoan parasites, chiefly of the genus Eimeria. Twenty-one
species of Eimeria have been reported in cattle.
Of the species of Eimeria that infect
cattle, E zuernii, E bovis, and E auburnensis are most often
associated with clinical disease. Experimentally, other
species have been shown to be mildly or moderately pathogenic.
Coccidiosis is commonly a disease of young
cattle of all breeds (1-2 mos to 1 yr).
Coccidiosis is uncommon in adult cattle,
but occasional cases and even epidemics do occur, especially
those from one to two years.
Older cattle are often carriers of
coccidia, and although they are immune, they continue to pass
oocysts in their manure.
The fecal-oral route transmits coccidiosis
from animal to animal. Infected fecal material contaminating
feed, water, or soil serves as carriers of the oocyst for the
susceptible animal to contract the disease by eating,
drinking, or licking itself.
Calves become infected when placed on
pastures or lots contaminated with sporulated oocysts from
older cattle or other infected calves. Mature cattle may be
infected when they are brought in from pastures and crowded
into feedlots or barns.
Recovered animals continue to carry and
excrete small numbers of oocysts
The incubation period is 17-21 days. The
severity of the disease depends on a number of factors
including the number of oocysts eaten, the species of coccidia
present and the age of the animal and stresses associated with
management factors. The severity of clinical disease depends
on the number of oocysts ingested. The more oocysts ingested
the more severe the disease. Calves with concurrent infections
(eg, coronavirus) may be more severely affected.
The most typical syndrome is chronic or
subclinical disease in groups of growing animals. There is
mild diarrhea and reduced growth rate, but not necessarily
dysentery too. Calves may appear unthrifty and have soiled
rear quarters. In lighter infections, cattle appear healthy
and oocysts are present in normally formed feces, but feed
efficiency may be reduced. Consequently, large numbers of
oocysts accumulate on the ground and these infect susceptible
calves when they are placed on the contaminated lots.
Clinical coccidiosis: Animals affected with
clinical coccidiosis often show watery diarrhea and dysentry,
with little or no blood, and the animal shows only slight
discomfort for a few days. Severe infections are rare.
Severely affected cattle develop diarrhea,
which consists of thin bloody fluid that may continue for > 1
wk, or thin feces with streaks or clots of blood, shreds of
epithelium, and mucus. Tenesmus, dehydration, weight loss,
depression, loss of appetite is common. They may develop a
fever in the early stages. During the acute period, some
cattle die; others die later from secondary complications (eg,
pneumonia). Cattle that survive severe illness can have
significant weight loss that is not quickly regained or can
remain permanently stunted
Fecal staining of hindquarters and tissue
pallor of the carcasses are common.
The pathogenic coccidia of cattle can
damage the mucosa of the lower small intestine, cecum, and
colon causing congestion, hemorrhagic enteritis, and
thickening of the mucosa. Ulceration or sloughing of the
mucosa may occur in severe cases.
The first-generation schizonts of E bovis
appear as white macroscopic cyst-like bodies in the villi of
the terminal ileum.
Diagnosis of clinical coccidiosis can be
made from a combination of herd history, clinical signs, gross
lesions at necropsy, and microscopic examination of faeces or
scrapings of the intestinal mucosa at necropsy.
Diagnosis is by finding oocysts on fecal
flotation, direct smear, or McMaster's technique.
An accurate way to diagnose coccidiosis at
necropsy is to examine scrapings of the small intestine or
colon for oocysts and merozoites. Merozoites can be looked for
in direct smears; they do not float on the conventional
concentrated sugar or salt solutions used for flotation of
The presence of large numbers of oocysts
can confirm the diagnosis, a count of 5000 oocysts per gram of
faeces is considered significant and below this count do not
usually suggest clinical disease but may indicate a potential
source of severe infection with favorable environmental
Care should be taken in interpretation of
oocyst counts since in severely affected diarrhoeic calves the
main oocyst production phase may have passed or their numbers
be misjudged due to the dilution factor of liquid faeces.
Usually, diarrhea precedes the heavy discharge of oocysts by a
day or two, and the diarrhea may continue after the oocyst
discharge has returned to low levels. Therefore, it is not
always possible to confirm a clinical diagnosis of coccidiosis
by finding oocysts in the faeces. Certain coccidia may cause
severe illness and even death before any oocysts have been
produced. This occurs most often with Eimeria zuernii in
calves. Consequently, failure to find oocysts in feces in a
diarrhea disease does not necessarily mean the disease is not
Differential diagnosis: Other conditions
that should be considered and may resemble coccidiosis are
salmonellosis, bovine virus diarrhea, malnutrition, toxins, or
other intestinal parasites.
Cattle that recover from coccidiosis usually
become immune to later infections, but they may continue to pass
oocysts in the manure, thereby providing a source of infection for
Although immunity against intestinal
coccidiosis is attributed to both humoral and cell-mediated immune
mechanisms but cellular immunity is more important in resistance
against reinfection than humoral immunity.
Bovine coccidiosis is immunosuppressive and
acts as a stressor causing an increased susceptibility to other
infections such as salmonellosis or bovine respiratory disease.
The acquired immunity after infection is
species specific and there is no cross immunity between species of
In clinical coccidiosis, the clinical signs
of the disease do not become noticeable until the disease is
advanced and much of the invasion of intestinal mucosa has
already occurred. Thus, treatment administered at this time
can at best result in a lessening of the signs of coccidiosis.
However, if drugs are given at an earlier stage of the
disease, the clinical signs of infection can be largely or
entirely prevented. The major benefits of the coccidiostats
are through improved feed efficiency and rate of gain.
There are several anticoccidial drugs
available that may be used. Outbreaks of coccidiosis in calves
and feeder cattle may be handled by mass medication using
sulfonamides, amprolium or monensin added to either the feed
or the water. Drugs useful for treatment are not necessarily
useful for prevention and vice versa,
Drugs that can be used for therapy of
clinically affected animals include;
-Sulfadimidine (sulfamerazine) 140 mg/kg BW /day for'3days orally.
-Sulfamethazine 110 mg/kg BW daily for 5 days.
-Sulfaquinoxaline 6 mg/lb BW /day for 3-5 days.
-Amprolium: 10 mg/kg BW /day for 5 days or 65 mg/kg 6W one dose followed
-5 mg/kg for 16 more days in feed or water.
Drugs can be very useful in helping to
prevent coccidiosis during periods when coccidiosis is likely
to be a hazard and some of these are;
• Amprolium 5 nig/kg BW/day for 21 days in feed
Monensin (Rumensin®) 16.5-33 gm/tonne for 31 days or 100-360
mg/head/day. Rumensin is very toxic if mixed improperly.
• Sulfadimidine (sulfamerazine) 35mg/kg BW /day for 15 days in
Lasalocid (Bovatec®) 1 mg/kg BW/day to a maximum of 360
Decoquinate (Deccox®) 22.7 mg/100 Ib BW/day for 28 days.
• Sulfonamides and chlortetracycline combination has given
protection in calves (lambs).
Prevention and control measure
Good management practices play a critical
role in the establishment of effective control programs.
Because several days are required for sporulation, the oocyst
stage in manure is the weakest link. Since moisture
Favors the development of parasites,
correction of housing and ventilation deficiencies that reduce
the moisture on pasture will decrease contamination.
Excessive moisture should be drained from
the pens and replaced with ample dry bedding and pastures
should be well-drained.
Cattle, especially calves, should not be
fed directly on the ground where manure can contaminate the
feed and the drinking water should be protected from
contamination by raising watering troughs above the ground.
In these areas where cattle congregate,
overgrazing should be avoided and grazing should be kept to a
minimum on lush grass along the edges of ponds.
Infected animals should be isolated and
treated to avoid exposure to other cattle
A. A. (1999):
"Veterinary Infectious Diseases" 2nd Edit. Ahram
Distribution Agency, Egypt.