VACCINATION IN POULTRY
Table 2. Eimeria species of turkeys included in commercially available vaccines. SPECIES
Eimeria adenoides (Moore and Brown, 1951)
Eimeria dispersa (Tyzzer, 1929)
Eimeria gallopavonis (Hawkins, 1952)
Eimeria meleagrimitis (Tyzzer, 1929)
Site with lesions
Site of multiplication
• Caeca • Ileum and rectum down to the cloaca
• The whole duodenum, jejunum, ileum and rectum • Caeca are not affected
• Ileum • Rectum
• Jejunum • Duodenum and ileum may also be affected
Characteristic lesions in GI tract
• First, oedema and petechia • Later, massive fibrinous cores
• Usually mild lesions • Intestinal wall thickened and cream-coloured
• Thickened mucosa covered with fibrinous and necrotic material
• Segments of affected intestines appear dilated and filled with fluid, mucoid content
Other lesions
• Weight loss • Mortality 100 % under experimental conditions
• Weight loss • Mucoid faeces
• Mortality can occur
• Dehydration • Disturbed general condition • Reduced weight gain • Mortality may occur
Oocysts
• Small to medium sized • Oblong
• Large • Ovoid
• Large • Oblong
• Small to medium sized • Ovoid
Additional information
Lesions may be suggestive of histomonosis. In 1910 Eimeria were mistakenly described as the causative agent of the “blackhead disease”.
In contrast to most other Eimeria species of poultry, E. dispersa is not host specific, but can infect several other gallinaceous birds. The bobwhite quail (Colinus virginianus ) seems to be the natural host.
After infection of a flock, which will almost inevitably occur, dry litter will slow down the sporulation of oocysts. Top dressing the litter and keeping drinkers and feeders clean will further help to limit the spread of the parasite and to reduce the infection pressure, which will lead to less damage, since the damage caused by infection with coccidia is directly linked to the infection dose. Regarding coccidiosis, “complete house sterilisation is never complete” (McDougald and Fitz-Coy, 2008) and can only be considered as a mean to reduce the initial infection pressure.
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Especially in broilers and turkeys, prophylaxis of coccidiosis relies heavily on the use of anticoccidial feed additives. Several different compounds can be used for that purpose, which have different modes of action and act on different stages. Traditionally, polyether ionophore antimicrobials like salinomycin, monensin or lasalocid are differentiated from “chemical” compounds, a heterogeneous group, including diclarzuril, nicarbazine and robenidine, among others.