E

Eimeria Species

Heinz Mehlhorn

Institut f€ur Zoomorphologie, Zellbiologie und

Parasitologie Universitatsstraße 1, D€usseldorf,

Germany

Name

The genus was named honoring Professor Eimer

(1843–1897), T€ubingen, Germany.

Geographic Distributions/Epidemiology

Worldwide; some species may introduce epi-

demics in young hosts (e.g., chickens, cattle)

which are kept very close together in stables.

Morphology/Life Cycle

The life cycle of the Eimeria species (Table 1)

mainly runs inside the intestine of plant feeders

(e.g., chickens, ruminants, and rodents) and in

some few omnivores (e.g., pigs) and is diagram-

matically depicted in Fig. 1. Infectious stages are

the oocysts, which are excreted unsporulated

(Fig. 2a) and which developed outside of the

body, four sporocysts each containing two sporo-

zoites (Figs. 2b and 3). If such “sporulated”

oocysts are ingested by a specific host – the

Eimeria species are extremely host

specific – the sporozoites enter the cells of the

host’s intestine and start within a parasitophorous

vacuole their life cycle (Figs. 4 and 5).

For details, see:

(A) ▶Eimeria species of ruminants

(B) Eimeria suis(C) Eimeria leuckarti of equids

(D) ▶Eimeria species of birds

(E) ▶Eimeria species of rabbits

(F) ▶Eimeria species of fish and relatives

Eimeria Species of Ruminants

Name

The genus name honors Professor Theodor

▶Eimer (1843–1897). Species names are related

to towns (e.g., Auburn), to their shapes (e.g.,

ellipsoidalis), to names of scientists (e.g., Nina

Kohl-Yakimov, Stieda, Danilov, etc.), or to

names of animals (e.g., bos = cattle).

Geographic Distributions/Epidemiology

Worldwide; some species may introduce epi-

demics among young animals in the same stable.

Often very high prevalence rates (~80 %) are

found in farmed animals.

Morphology/Life Cycle

For each host group (cattle, sheep, and goats),

always around 10 specific species have been

# Springer-Verlag Berlin Heidelberg 2015

H. Mehlhorn (ed.), Encyclopedia of Parasitology,DOI 10.1007/978-3-642-27769-6_3833-1

Eim

eriaSpecies,Table

1Im

portantspeciesofthegenusEimeria

Species

Host/habitat

Oocystsize

(mm)

Prepatentperiod(days)

Pathogenicity

Cattle

E.bo

vis

Posteriorsm

allintestine

23–34�

17–23

15–21

+

E.au

burnensis

Smallintestine

36–42�

19–26

17–20

+

E.zuernii

Smallintestine

16–20�

15–18

15–19

+

E.ellipsoidalis

Smallintestine

18–26�

13–18

8–13

+

Sheep

E.fauri

Smallintestine

22–33�

19–24

12–15

+

E.intricata

Smallintestine,cecum

40–56�

30–41

20–27

+

E.ovina

Smallintestine

23–36�

16–24

19

+

E.ovinoida

lis

Colon

17–25�

13–20

10–15

+

Goats

E.arloingi

Intestinalcrypts

25–33�

16–21

14–20

+

E.nina

kohlyakimovae

Intestinalcrypts

16–28�

14–23

11–17

+

E.christenseni

34–41�

23–38

14–23

+

Pigs

E.scabra

Smallintestine

25–45�

17–28

7–10

+

E.suis

Smallintestine

13–20�

11–15

10

+

Horses

E.leuckarti

Smallintestine

70–90�

50–69

31–37

�Rabbits

E.intestinalis

Cecum,colon

23–32�

15–20

10

+

E.perforans

Smallintestine

16–28�

12–16

4–6

+

E.magn

aSmallintestine

28–40�

18–30

7–9

+

E.stiedae

(syn.E.stiedai)

Bileducts

26–40�

16–25

12–16

+

2 Eimeria Species

Rats

E.contorta

Wholeintestine

18–27�

15–21

6�

E.nieschu

lzi

Smallintestine

16–26�

13–21

7–8

+

Mice

E.falciparum

Cecum,colon

16–21�

11–17

4–5

+

E.ferrisi

Cecum

17–20�

14–16

4–5

�Chickens

E.tenella

Cecum

23�

19(m

ean)

6+

E.maxima

Smallintestine

30�

20(m

ean)

5+

E.necatrix

Smallintestine

22�

17(m

ean)

6+

E.praecox

Smallintestine

21�

17(m

ean)

4�

Geese

E.trun

cata

Kidneys

15–22�

11–16

5+

E.an

seris

Smallintestine

16–23�

13–18

7+

E.no

cens

Colon

25–33�

17–24

9+

Ducks

E.dan

ailovi

Smallintestine

19–22�

11–14

7+

Turkeys

E.adenoeides

Colon,cecum

25�

17(m

ean)

5+

E.meleagrimitis

Smallintestine

20�

17(m

ean)

5+

Pigeons

E.labb

eana

Smallintestine

15–18�

14–16

6+

E.columba

rum

Smallintestine

19–21�

17–20

6�/

+

Eimeria Species 3

Eimeria Species, Fig. 1 Life cycle of Eimeria sp. in

chicken. For species and other hosts, see Table 1. 1 After

oral uptake of sporulated oocysts, the sporozoites hatch in

the small intestine from the sporocysts. 2–6 After

penetration, multinucleate ▶ schizonts are formed (3)inside a ▶ parasitophorous vacuole (PV). The schizonts

produce motile ▶merozoites (DM, M). 7 Formation of

multinucleate ▶microgamonts, which develop many

4 Eimeria Species

described, which appear morphologically differ-

ent and are also different with respect to their

pathogenicity. However, in many cases, the

exact species determination remains difficult.

Their life cycle runs in principle like that of the

Eimeria species being depicted in Fig. 6 of the

keyword ▶Eimeria; however, the site of parasit-

ism or the number of schizogonies, etc. may vary

considerably. The following species are common

and/or very pathogenic: Cattle – E. bovis,

E. auburnensis, E. zuernii, and E. ellipsoidalis;

Sheep – E. faurei, E. intricata, E. ovina, andE. ovinoidalis; and Goat – E. arloingi,

E. ninakohlyakimovae, and E. christenseni.

They all proceed their development intracellu-

larly inside the typical final host (i.e., they are

host specific), and their infectious stages

(oocysts) are excreted unsporulated.

Symptoms of Disease (Coccidiosis)

This disease (see ▶Coccidiosis of animals)

affects mainly young animals, while elder ones

develop immunity. Typical symptoms are bloody

diarrheas due to destruction of the epithelia and

underlying cells inclusively blood vessels. Since

the diarrhea may be very voluminous, often

exsiccosis may occur. Bacterial superinfections

may increase the severity of the symptoms. In

case of severe infections, the following symp-

toms occur besides diarrheas: fever, tetanic

cramps, and bloody feces, and especially in

young animals, high mortality rates are common.

In cattle, hemorrhagic typhlitis and colitis are

common in infections with E. bovis and

E. zuernii, while E. alabamensis,

E. auburnensis, and E. ellipsoidalis introduce

catarrhal enteritis. In the case of sheep,

E. ovinoidalis leads to hemorrhagic enteritis,

while E. fauri often introduces the symptoms of

a catarrhal enteritis.

Diagnosis

Microscopical analysis of the oocysts after con-

centration with the help of the ▶ flotation

method.

Infection

Oral uptake of sporulated oocysts.

Prophylaxis

Since the oocysts are excreted unsporulated, the

regular cleaning of stables from feces is very

helpful to avoid infections with infectious

(sporulated) oocysts. This cleaning should be

done with hot steam and/or by use of commercial

disinfectants (e.g., Lysococ®, Club-TV

Anticoc®, P3 Jucicoc®, etc.) In some countries,

also anticoccidial food additions are allowed

(e.g., monensin-Na) at doses of 10–30 mg/kg

food for cattle, lambs, and goats – when not

being used for milk production. However, use of

chemical prophylactic products is expensive and

thus often not done. Therefore, it is very impor-

tant to observe the farmed animals and to start

treatment as early as possible in cases of observed

infections.

��

Eimeria Species, Fig. 1 (continued) flagellated▶micro-

gametes (7.1–7.2). 8 Formation of uninucleate

macrogamonts, which grow to be macrogametes (8.1)that are characterized by the occurrence of two types of

▶wall-forming bodies (WF 1,WF 2). 9After fertilization,the young ▶ zygote forms the ▶ oocyst wall by consecu-

tive fusion of both types of wall-forming bodies (WF). 10Unsporulated oocysts are set free via feces (exceptions are

reptile- and fish-parasitizing Eimeria spp.). 11–13▶ Sporulation (outside the host) is temperature-dependent

and leads to formation of four sporocysts, each containing

two sporozoites (SP), which are released when the

▶ oocyst is ingested by the next host. DG developing

▶microgametes,DM developing▶merozoite,DW devel-

oping wall-forming bodies, FW fusion ofWF 1 to form the

outer layer of OW, M merozoites, N nucleus, NH nucleus

of host cell, OW oocyst wall, PB polar body (granule), PV▶ parasitophorous vacuole, R refractile (reserve) body, SB▶ sporoblast, SP ▶ sporozoite, SPC ▶ sporocyst, SPOsporont, WF 1 wall-forming bodies I, WF 2 wall-forming

bodies II, Z ▶ cytoplasm of zygote (young oocyst)

Eimeria Species 5

Incubation Period

The timing is species specific and also depends on

the amount of ingested oocysts; however, symp-

toms of disease mostly start within 1 week after

infection.

Prepatent Period

Species specific: 6–35 days.

Patency

A few weeks.

Therapy

The use of medicaments to control coccidiosis is

regulated by national health authorities. Thus,

many compounds are not available everywhere.

Cattle, sheep, and goats may be treated by

▶ toltrazuril, sulfonamides, or combination prep-

arations (see ▶Coccidiocidal drugs).

Eimeria and Isospora Species of Pigs

See ▶Coccidia of swine.

Eimeria (Synonym, Globidium) leuckartiof Equids

Name

The genus name Eimeria honors Prof.

Dr. Theodor ▶Eimer (1843–1897). The species

name honors Prof. Dr. ▶Leuckart (1822–1898).

Geographic Distributions/Epidemiology

Worldwide, due to horse transportations all over

the world. In Central Europe, up to 80 % of the

foals may be infected.

Morphology/Life Cycle

E. leuckarti is the onlyEimeria species in equids. The

oocysts are rather large (70–90 mm � 50–69 mm)characterized by an extremely thick (8–10 mm)

and outer oocyst wall and a smooth inner one

(Fig. 3). The schizogony and gamogony proceed

in cells of the intestinal wall. Schizogony was

found in epithelial cells, while gamogony was

documented in cells of the lamina propria. Spor-

ulation time outside of the body takes about

2 weeks.

Eimeria Species,Fig. 2 Light micrograph

of unsporulated (a) and a

sporulated (b) oocysts ofEimeria tenella from

chicken

6 Eimeria Species

Symptoms of Disease

Mostly no or only low-grade symptoms of dis-

ease occur. However, young or diseased horses,

camels, etc. may suffer from diarrheas. Foals start

to excrete oocysts from days 28 until 190; after-

ward, only rare cases of disease occur.

Diagnosis

Microscopical demonstration of the typical

oocysts obtained by use of ▶ concentration

methods of feces (▶ flotation; ▶ S.A.F.). Since

these oocysts are very heavy, it is needed to

centrifuge the flotation medium for 7–8 min.

Infection

Oral via contaminated food or drinking water.

Prophylaxis

Regular cleaning of the stables with the help of

hot steam and use of disinfectants (see ▶ cattle).

Incubation Period

Two to three weeks (after experimental

infections).

Prepatent Period

Rather long: 28–37 days in young animals.

Patency

Three to four weeks.

Therapy

Toltrazuril; however, treatment is only needed in

case of symptoms of disease.

Eimeria Species, Fig. 3 Diagrammatic representation of

a sporulated oocyst of the genus Eimeria containing four

sporocysts with two sporozoites each. AW outer layer of

the wall of the oocyst, IW inner layer of the wall of the

oocyst, MK cap of micropyle, N nucleus, PK polar body,

RK refractile body, RO residual body of the oocyst, RSresidual body of the sporocyst, S sporocyst, SP sporozoite,

ST Stieda body, SST substieda body

Eimeria Species, Fig. 4 Light micrograph of the bloody

ceca of a chicken infected with Eimeria tenella

Eimeria Species 7

Eimeria Species and Related Coccidiaof Birds

Name

The genus name Eimeria honors the Swiss-born

Professor Theodor ▶Eimer (1843–1897). The

species names honor scientists, describe host

names, refer to their outer appearance, or are

given according to their location in hosts.

Geographic Distributions/Epidemiology

Worldwide; outbreaks in large breeding facilities

may reach the status of local epidemics.

Morphology/Life Cycle

The life cycle is diagrammatically depicted in

Fig. 1. Some species of farmed animals are very

pathogenic and thus they are of huge economic

importance. A broad spectrum of host-specific

Eimeria species occur in the different birds

(Figs. 4, 5 and 7).

Chicken

Many species are described; some of them produce

significant and often severe pathogenic effects:

E. acervulina, E. mitis (anterior small intestine),

E. brunetti (ileum and rectum), and E. tenella

(ceca) (Figs. 4 and 5) E. mivati and E. hagani are

Eimeria Species, Fig. 5 Diagrammatic representation of

the sites of infection of Eimeria species in chicken intes-

tine. (a) E. acervulina, (b) E. brunetti, (c) E. hagani, (d)

E. maxima, (e) E. mivati, (f) E. mitis, (g) E. necatrix, (h)E. praecox, (i) E. tenella. B cecum, C colon,D duodenum;

P pylorus; Z jejunum (shortened)

8 Eimeria Species

of low pathogenicity and E. praecox is even

described as apathogenic.

Geese

Pathogenic species are E. anseris and E. nocens(small intestine and colon), E. truncata (in kidney

epithelium), and E. kotlani (rectum, cloaca).

Ducks

E. kotlani,E. danailovi, Tyzzeria perniciosa (small

intestine), and E. adenoeides are the most patho-

genic species in the posterior regions of the small

intestine (ileum) but also in the ceca and colon.

Pigeons

E. labbeana and E. columbarum (in the mid

region of the small intestine) are both pathogenic.

Parrots

E. dunsigni (in the small intestine) – this species is

pathogenic, but occurs only rarely in farmed birds.

Symptoms of Disease (Coccidiosis,

Coccidiasis)

Characteristic symptoms of an acute coccidiosis

are severe, sometimes bloody, diarrheas based on

catarrhal or hemorrhagic enteritis. The feces

appear watery fluid, contain slimy or bloody ele-

ments, or appear yellowish-greenish. High mor-

tality rates occur in some species (e.g., E. tenella;

Fig. 4); thus, an outbreak of a coccidiosis may

lead to enormous economic losses (Fig. 8).

Diagnosis

Microscopical determination of oocysts in the

feces after use of ▶ flotation method.

Infection

Oral uptake of sporulated oocysts with contami-

nated food or drinking water.

Eimeria Species, Fig. 6 Light micrographs (a, b) andscanning electron micrograph (c) of oocysts of Eimerialeuckarti. (a) Intact oocyst. (b) The outer oocyst wall is

ruptured, thus making visible the inner oocyst wall. (c)

These SEM-micrographs gives an impression of the outer

surface of the oocyst wall. A rupture in the outer layer of

the oocyst wall, DS thick outer oocyst wall, VE dorsal

depression of the outer oocyst wall (site of rupture)

Eimeria Species 9

Prophylaxis

(a) Hygienicmeasurements: Regular cleaning of

cages or soil/floors from feces. Protect

drinking water from fecal contaminations.

Disinfect stables, floors, and cages with the

help of registered disinfectants. Important:

Eimeria Species, Fig. 7 Light micrographs of infected chicken intestines. (a) E. acervulina. (b) E. maxima

Eimeria Species, Fig. 8 Light micrographs of intestinal

protozoans of ruminants. (a) Cyst of Giardia sp. (b)Oocysts of Cryptosporidium species. (c–f) Eimeriaoocysts: (c) E. granulosus in fresh sheep feces, (d)E. ovina from sheep, sporulated stage, (e) E. bovis,unsporulated stage from fresh feces of cattle, and (f)

E. intricata – sporulated oocyst from sheep feces with its

characteristic thick wall (for details of each species, see

▶Eimeria, Table 1). CW cyst wall, MP micropyle, Nnucleus, OW oocyst wall, RB residual body, S sporozoite;SP sporocyst, Z zygote cytoplasm

10 Eimeria Species

Use always the all in-all out principle for

stables with farmed birds, i.e., take always

all animals out of a stable after a period of

egg laying or a period of fattening; clean

equipment and floors and then enter all new

birds at once. Never add single birds to a

stable with healthy animals.

(b) Chemoprophylaxis: The basics of this

method is to feed permanently small, but

efficient amounts of ▶ coccidiocidal drugs.

This method, however, may introduce resis-

tances against several coccidiocidal

medicaments.

(c) Immunization: There exist several vaccines

(containing attenuated, low-grade patho-

genic oocysts); however, many of them are

only registered in a certain number of coun-

tries (e.g., Coccivac®, Paracox®, Livacox®,

etc.). The problem is that these strains may

recover their full pathogenicity after some

periods of use.

Incubation Period

Three to five days depending on the number of

ingested oocysts and the grade of the pathogenic-

ity of the ingested Eimeria species.

Prepatent Period

The different Eimeria species need different

periods until oocysts appear in feces:

(a) Chickens: 4 days (E. praecox, E. acervulina,

E. mitis, E. mivati); 5 days (E. maxima,

E. brunetti, E. tenella); 6 days (E. necatrix).(b) Turkeys: 4 days (E. dispersa); 5 days

(E. meleagrimitis, E. adenoeides).

Eimeria Species, Table 2 Food additions in chicken food to avoid coccidiosis

Chemicidial name Trade name Producer Animals (maximum age)

Dose

(ppm)

(waiting

time)

Meticlorpindol Coyden® Dow Fattened hen, keets 125

(5 days)

Decoquinate Deccox® Rhone-Poulenc

(May and Baker)

Fattened hen 20–40

(3 days)

Monensin-Natrium Elancoban®

(Coban)

Elanco (Eli Lilly) Fattened hen young chicken

(16 weeks), turkeys (16 weeks)

100–125

(3 days)

100–120

90–100

(3 days)

Robenidine Cycostat® Cyanamid Fattened hen, turkeys 30–36

(5 days)

Lasalocid-Natrium Avatec® Roche Fattened hen, young chicken

(16 weeks), turkeys (12 weeks)

75–125

(5 days)

90–125

(5 days)

Narasin Monteban® Elanco (Eli Lilly) Fattened hen 60–70

(3 days)

Salinomycin-Na Sacox® Hoechst Fattened hen 50–70

(5 days)

Nicarbazin Altek® 25 MSD Fattened chicken (4 weeks) 100–125

(9 days)

Maduramicin-

ammonium

Cygro® Cyanamid Fattened hen 5 (7 days)

Narasin/nicarbazin

granula 1:1

Maxiban® Elanco (Eli Lilly) Fattened hen 80–100

(7 days)

Diclazuril Clinacox® Janssen Fattened hen 1 (5 days)

Eimeria Species 11

(c) Geese: 5 days (E. truncata); 7 days

(E. anseris); 9 days (E. nocens).

(d) Ducks: 6 days (E. perniciosa); 8 days

(E. danilovi).(e) Pigeons: 6 days (E. labbeana).

(f) Parrots: 5 days (E. dunsigni).

Patency

Mostly rather short (1–3 weeks); however, also

slight infections had been reported to occur for

months (due to repeated self-infections).

Therapy

Against many of the “older” anticoccidial com-

pounds, resistances have been developed. Thus,

the products based on toltrazuril (e.g., Baycox®

15–20 mg/kg bodyweight in drinking water) are

widely used. For further information, see

▶Coccidiocidal Drugs and Table 2.

Eimeria Species of Rabbits

Name

The genus name Eimeria honors the Swiss-born

Prof. Dr. Theodor ▶Eimer (1843–1897). The

species name describes activities (e.g., Latin:

perforans, penetrating) and sites of infections

(e.g., Latin: intestinalis, inside the intestine) or

honors scientists (e.g., Christian Stieda,

1837–1918).

Geographic Distributions/Epidemiology

Worldwide; in farmed animals small epidemics

may occur.

Morphology/Life Cycle

The members of the Lagomorpha are parasitized

by a large number of Eimeria species, which

mostly enter the epithelial cells of the small intes-

tine. However, E. stiedae (Fig. 9) which parasit-

izes in liver cells of rabbits is one of the most

important pathogens. E. intestinalis,E. perforans, and E. magna infect also rabbits

and are very pathogenic. E. contorta and

Eimeria Species, Fig. 9 Light micrographs of unsporulated and sporulated E. stiedae oocysts. MP micropore, OWoocyst wall, SP sporocyst

Eimeria Species, Fig. 10 Liver of an Eimeriastiedae-infected liver

12 Eimeria Species

E. nieschulzi are found in rats, whereas

E. falciparum and E. ferrisi parasitize in mice

(e.g., laboratory mouse: Mus musculus).

Symptoms of Disease (Rabbits)

(a) Intestinal coccidiosis leads to severe diar-

rheas combined with anemia, extreme weak-

ness, and loss of weight. The effects of these

infections are mostly increased by bacterial

superinfections leading to high mortality

rates.

(b) Liver coccidiosis of rabbits is initiated by

Eimeria stiedae. Main symptoms are liver

dysfunctions (loss of activity) and appear-

ance of yellow-whitish nodes in and on the

liver (Fig. 10) and destruction of the parasit-

ized epithelia of the excreting channels of the

gall bladder system.

Diagnosis

Microscopical inspection of the fecally excreted

oocysts with the help of concentration methods

(e.g., ▶ flotation).

Infection

Oral uptake of sporulated oocysts with contami-

nated food or drinking water.

Prophylaxis

Regular cleaning of the cages. Avoidance to add

new animals into an existing system without pre-

vious isolation (= quarantine) of newcomers.

Incubation Period

Mostly less than 1 week.

Prepatent Period

Species specific: 9–12 days (E. intestinalis);

12–14 days (E. stiedae).

Patency

Mostly 2–5 weeks, with highest excretion rates

during the first and second week of patency.

Therapy

Toltrazuril (Baycox®), 25 ppm in drinking water

for 2 days; repetition after 5 days.

Further Reading

Bahat TK et al (1996) Rabbit coccidiosis and its control.

World Rabbit Sci 4:37–41

Beelitz P et al (1994) Eimeria leuckarti. Infektionen bei

Fohlen und ihren Mutterstuten in Oberbayern.

Tierarztl Prax 22:377–381

Daugschies A, Najdrowsk M (2005) Eimeriosis in cattle:

current understanding. J Vet Med B Infect Dis Vet

Public Health 52:417–427

Levine ND (1988) The protozoan phylum Apicomplexa,

vol I and II. CRC Press, Boca Raton

Levine ND, Ivens V (1990) Coccidian parasites of rodents.

CRC Press, Boca Raton

Mehlhorn H (1972–1974) Electron microscopical investi-

gations on the developmental stages of Eimeria max-ima (macrogametes, microgametes, schizonts,

merozoites). Parasitol Res 39, 40:161–182, 151–163,

243–260

Mehlhorn H (2012) The parasites of animals, 7th edn.

Springer Spectrum, Heidelberg

Pellerdy L (1984) Coccidia and coccidiosis, 2nd edn.

Parey, Berlin

Scholtyseck E, Mehlhorn H (1970) Ultrastructural study

of characteristic organelles of Sporozoa. Parasitol Res

34:97–127

von Samson-Himmelstjerna G et al (2006) Clinical and

epidemiological characteristics of Eimeria infections

in first-year grazing cattle. Vet Parasitol 136:215–221

Eimeria Species 13