Eimeriosis in Cattle: Current Understanding

Abstract

This report addresses various aspects of the protozoan parasite Eimeria which contribute to their increasing recognition as important protozoal pathogens in cattle. Among others, questions of parasite biology and epidemiology, its impact on host physiology, and control strategies are dealt with. The tenacious oocysts are found ubiquitously in the environment making an infection of calves and young cattle, the most susceptible age group, almost inevitable. Further development, comprising of asexual multiplication, the merogony, and a subsequent sexual stage, the gamogony, takes place within cells of the small and large intestines, after which numerous unsporulated oocysts are formed and shed with the faeces. Of the more than a dozen species, Eimeria bovis and Eimeria zuernii only are made responsible for severe clinical disease characterized by haemorrhagic diarrhoea with sometimes fatal outcome. To a lesser extent, Eimeria alabamensis also can cause clinical disease. Because of the damage inflicted on the intestinal tissue, the digestive process and overall homeostasis can become severely affected, even with absence of clinical disease, with adverse effects on animal welfare and performance. The consequent economic losses for the cattle industry are thus substantial. Active (species specific) immunity, both humoral and cellular, develops rapidly after first antigen contact, its intensity being dependent on the number of oocysts ingested. However, no absolute protection is achieved and even older animals can excrete oocysts, contributing to a state of endemic stability. For efficient control, exact diagnosis of the Eimeria species involved and the evaluation of animal management and husbandry practices are of utmost importance. Mixed infections are the rule and only an occurrence of pathogenic species, together with clinical symptoms, justifies the assumption of a coccidiosis. Proper hygiene regime and ensuring unfavourable conditions for oocyst survival in the environment (cool and dry, disinfection procedures) will help to reduce infection pressure on the herd. Of the various pharmacological compounds used to treat coccidiosis, those which act against the late developmental stages, administered during prepatency (metaphylactically rather than therapeutically), are currently considered most effective.

Eimeria infections in goats in Southern Portugal

“…In contrast to these findings, other studies have reported a slight increase in the excretion of oocysts among goats older than seven years of age, which has been interpreted as relative weakness of the host immune system (CHARTIER; PARAUD, 2012). Occasionally, host protective immune reactions against Eimeria infections fail due to adverse conditions, involving stress, dietary changes, prolonged travel, extremes of temperatures, weather conditions, environment changes, severe concomitant infections, nutritional status and other factors (TAYLOR;CATCHPOLE, 1994;DAUGSCHIES;NAJDROWSKI, 2005;RUIZ et al, 2006).…”

Assessment of risk factors associated with prevalence of coccidiosis in dairy animals of Punjab

“…have been described in dairy animals, most of which are considered non-pathogenic and mixed infections are generally encountered (Daugschies and Najdrowski 2005). Eimeria bovis and E. zuernii, are particularly more pathogenic to calves and young animals while E. alabamensis has been reported to cause clinical disease in older animals.…”

“…cattle, sheep, goats, buffaloes, rabbits and poultry worldwide (Daugschies and Najdrowski 2005) is caused by microscopic apicomplexan organisms called coccidia. The disease is present in clinical form mostly in younger animals; however, adults may also be affected severely, at times.…”

Frequency of species of the Genus Eimeria in naturally infected cattle in Southern Bahia, Northeast Brazil

“…Adult animals are usually asymptomatic carriers that often serve as a source of infection for juvenile animals, which are more susceptible to parasitosis (COURTNEY; ERNST; BENZ, 1976;CHIBUNDA et al, 1997;MATJILA;PENZHORN, 2002;NAJDROWSKI, 2005).…”