Eimeria

Eimeria
Eimeria maxima oocysts
Scientific classification
Domain:	Eukaryota
(unranked):	Sar
(unranked):	Alveolata
Phylum:	Apicomplexa
Class:	Conoidasida
Order:	Eucoccidiorida
Family:	Eimeriidae
Genus:	Eimeria Schneider, 1875
Type species
Eimeria falciformis [1] (Eimer, 1870) Schneider, 1875
Species
See text

Eimeria is a genus of apicomplexan parasites that includes various species capable of causing the disease coccidiosis in cattle and poultry, among other animals. The most prevalent species of Eimeria that cause coccidiosis in cattle would be E. bovis, E. zuernii, and E. auburnensis.^[2] In a young, susceptible calf it is estimated that as few as 50,000 infective oocysts can cause severe disease.^[3] The oocysts of what was later called Eimeria steidai were first seen by the pioneering Dutch microscopist Antoni van Leeuwenhoek (1632–1723) in the bile of a rabbit in 1674. The genus is named for the German zoologist Theodor Eimer (1843–1898).

Description

The coccidia genera can be identified from oocysts:

Eimeria - four sporocysts, each containing two sporozoites

Wenyonella - four sporocysts, each containing four sporozoites

Tyzzeria - eight sporozoites, not contained in sporocysts

Isospora - two sporocysts, each containing four sporozoites

Taxonomy

The Eimeria lie within the family Eimeriidae. This genus has ~75% of the species within this family, and it is the most specious of the genera of the Apicomplexia with 1,700 described species.

Attempts to subdivide this large taxonomic unit into separate genera have been made.

The Eimeria of fish have been divided into four genera based on available morphologic and life cycle data.

Eimeria: these species are tetrasporocystic with dizoic, nonbivalved sporocysts with or without Stieda bodies. This new genus retains the majority of the species.

Goussia (Labbe 1896): These species are tetrasporocystic, dizoic, lack Stieda bodies, and have sporocyst walls consisting of two valves joined by a longitudinal suture. This genus contains about 20 species.

Crystallospora (Labbe 1896): The species in this genus is tetrasporocystic and dizoic, and have dodecahedral sporocysts composed of two hexagonal, pyrimidal valves joined at their bases by a suture. This genus contains a single species, Crystallospora cristalloides (Thelohan 1893).

Epieimeria (Dykova and Lorn 1981): the species in this genus are tetrasporocystic, dizoic, possess Stieda bodies, and undergo merogony and gametogony on the lumenal surface of the intestinal tract. Three species are in this genus.

Pathology

Symptoms of Eimeria infection include bloody diarrhea due to intestinal epithelium dying off when a large number of oocysts and merozoites burst out of the cells. The severity of the disease is directly dependent on the number of infective Eimeria oocysts that are ingested by the bovine. In light infections the damage to the gut might only be minimal and be rapidly repaired as cells are rapidly replaced by the body. However, in heavy infections it may only take two weeks for many intestinal epithelial cells to be infected with either Eimeria meronts or gametocytes. These cause the epithelial cells to burst, which causes significant damage to the intestine epithelial layer, and releases blood, fluid, and electrolytes into the intestine.^[3]

Clinical

Medications are available for the parasite; however, drug resistance is common, as well as possible drug residues in the meat once the animal is butchered. Vaccines have been developed, but one vaccine will only cover one species and not others. So far, the best practice is to vaccinate the chicks once they hatch from the egg so they are immune for life.

In case of an infection in cattle with Eimeria, the approximate amount of time it takes for diarrhea to occur after infection is 16–23 days for E. bovis and E. zuernii, and 3–4 days for E. alabamensis.^[2]

Human

Five genera are known to cause infections in humans: Cryptosporidium, Cyclospora, Isospora, Sarcocystis, and Toxoplasma. Of these, the first three normally are confined to the gastrointestinal tract and cause diarrhea and abdominal pain. The other two invade the body tissues and may be found in multiple organs.

Treatments

The following drugs can be used for treatment of coccidiosis in cattle: Amprolium, Sulfaquinoxaline, and Sulfamethazine. However, it is often more effective to prevent this disease in cattle, which can be aided by the products Lasalocid, Decoquinate, and Monensin.^[3]

Host range

All mammalian coccidia are considered to be host-specific, but a limited number of exceptions to this rule have been identified. Thirty-one species are known to occur in bats (Chiroptera) and two in turtles; 130 named species infect fish.

Two species (E. phocae and E. weddelli) infect seals. Five species infect llamas and alpacas - E. alpacae, E. ivitaensis, E. lamae, E. macusaniensis, and E. punonensis. A number of species infect rodents, including E. couesii, E. kinsellai, E. palustris, E. ojastii and E. oryzomysi. Others infect poultry (E. necatrix and E. tenella), rabbits (E. stiedae) and cattle (E. bovis, E. ellipsoidalis, and E. zuernii).

Genomics

A genome-sequencing project is in progress. The species chosen is Eimeria tenella. The genome is about 60 megabases in size and has a GC content around 53%. The 14 chromosomes range in size from 1 to >6 megabase. Since 2013 the sequencing and annotation of further six avian Eimeria species genomes is in progress.

Host-parasite relations

Fish

Eimeria aurati - goldfish (Carassius auratus)
Eimeria baueri -crucian carp (Carassius carassius)
Eimeria lepidosirenis - lungfish (Lepidosiren paradoxa)
Eimeria leucisci - barbel (Barbus barbus bocagei)
Eimeria rutili - Europena chub (Leuciscus cephalus cabeda), Iberian nase (Chondrostoma polylepis polylepis)
Eimeria vanasi - blue tilapia (Oreochromis aurea)

Reptiles

Eimeria amphisbaeniarum - Mann's worm lizard (Amphisbaena manni)
Eimeria witcheri - Mann's worm lizard (A. manni)
Eimeria yemenensae - rock agama (Agama yemenensis)

Birds

Eimeria acervulina - chicken (Gallus gallus domesticus)
Eimeria adenoeides - turkey (Meleagris gallopavo)
Eimeria brunetti - chicken (G. g. domesticus)
Eimeria colchici - pheasant (Phasianus colchicus)
Eimeria curvata - ruddy ground dove (Columbina talpacoti), scaled dove (Scardafella squammata)
Eimeria dispersa - turkey (M. gallopavo), bobwhite quail (Colinus virginianus)
Eimeria duodenalis - pheasant (Phasianus colchicus)
Eimeria fraterculae - Atlantic puffin (Fratercula arctica)
Eimeria gallopavonis - turkey (M. gallopavo)
Eimeria innocua - turkey (M. gallopavo)
Eimeria praecox - chicken (G. g. domesticus)
Eimeria maxima - chicken (G. g. domesticus)
Eimeria meleagridis - turkey (M. gallopavo)
Eimeria meleagrimitis - turkey (M. gallopavo)
Eimeria mitis - chicken (G. g. domesticus)
Eimeria necatrix - chicken (G. g. domesticus)
Eimeria phasiani - pheasant (P. colchicus)
Eimeria procera - grey partridges (Perdix perdix)
Eimeria tenella - chicken (G. g. domesticus)

Mammals

Eimeria ahsata - goat (Capra hircus), sheep (Ovis aries)
Eimeria alabamensis - cattle (Bos taurus)
Eimeria alijevi - goat (C. hircus)
Eimeria apsheronica - goat (C. hircus)
Eimeria arloingi - goat (C. hircus)
Eimeria arundeli - common wombat (Vombatus ursinus)
Eimeria bakuensis - sheep (O. aries)
Eimeria bovis - cattle (B. taurus)
Eimeria cameli - camels (Camelus bactrianus,Camelus dromedarius)
Eimeria caprina - goat (C. hircus)
Eimeria caprovina - goat (C. hircus)
Eimeria christenseni - goat (C. hircus)
Eimeria clethrionomyis - red-backed vole (Clethrionomys gapperi)
Eimeria coecicola - rabbit (Oryctolagus cuniculus)
Eimeria contorta - mouse (Mus musculus)
Eimeria couesii - rice rat (Oryzomys couesi)
Eimeria crandallis - sheep (O. aries)
Eimeria dammahensis - scimitar-homed oryx (Oryx dammah)
Eimeria dowleri - eastern red bat (Lasiurus borealis)
Eimeria exigua - rabbit (O. cuniculus)
Eimeria falciformis - mouse (M. musculus)
Eimeria farasanii - mountain gazelle (Gazella gazelle farasani)
Eimeria ferrisi - mouse (M. musculus)
Eimeria flavescens - rabbit (O. cuniculus)
Eimeria gallatii - red-backed vole (C. gapperi)
Eimeria granulosa - goat (C. hircus)
Eimeria hirci - goat (C. hircus)
Eimeria intestinalis - rabbit (O. cuniculus)
Eimeria irresidua - rabbit (O. cuniculus)
Eimeria intricata - goat (C. hircus)
Eimeria jolchijevi - goat (C. hircus)
Eimeria krijgsmanni - mouse (M. musculus)
Eimeria larimerensis - Uinta ground squirrel (Spermophilus armatus)
Eimeria macusaniensis - llamas (Lama glama), guanacos (Lama guanicoe), alpacas (Vicugna pacos), vicunas (Vicugna vicugna)
Eimeria magna - rabbit (O. cuniculus)
Eimeria marconii - red-backed vole (Clethrionomys gapperi)
Eimeria media - rabbit (O. cuniculus)
Eimeria melanuri - garden dormouse (Eliomys quercinus)
Eimeria myoxi - garden dormouse (E. quercinus)
Eimeria nagpurensis - rabbit (O. cuniculus)
Eimeria nieschulzi - brown rat (R. norvegicus)
Eimeria ninakohlyakimovae - goat (C. hircus)
Eimeria ovinoidalis - sheep (O. aries)
Eimeria pallida - goat (C. hircus)
Eimeria palustris - marsh rice rat (Oryzomys palustris)
Eimeria papillata - mouse (M. musculus)
Eimeria perforans - rabbit (O. cuniculus)
Eimeria phocae - Sable Island harbour seals (Phoca vitulina)
Eimeria pileata - red-backed vole (Clethrionomys gapperi)
Eimeria pipistrellus - Kuhl's pipistrelle (Pipistrellus kuhlii)
Eimeria piriformis - rabbit (O. cuniculus)
Eimeria prionotemni - Bennett's wallaby (Macropus rufogriseus)
Eimeria procyonis - raccoon (Procyon lotor)
Eimeria punctata - goat (C. hircus)
Eimeria roobroucki - rabbit (O. cuniculus)
Eimeria saudiensis - Arabian oryx (Oryx leucoryx)
Eimeria sealanderi - eastern red bat (Lasiurus borealis)
Eimeria separata - mouse (M. musculus), rat (Rattus rattus)
Eimeria stiedae - rabbit (O. cuniculus)
Eimeria ursini - southern hairy nosed wombat (Lasiorhinus latifrons)
Eimeria vermiformis - mice (M. musculus)
Eimeria weybridgensis - sheep (O. aries)
Eimeria wobati - southern hairy-nosed wombat (L. latifrons)
Eimeria zuernii - cattle (B. taurus)

List of species

Life cycle

Eimeria life cycle

References