Epidemiological investigation and drug resistance of Eimeria species in Korean chicken farms

Abstract

Background Coccidiosis is a poultry disease that occurs worldwide and is caused by Eimeria species. The infection is associated with reduced feed efficiency, body weight gain, and egg production. This study aimed to investigate the current status of coccidiosis and anticoccidial resistance to anticoccidial drugs used as part of control strategies for this disease in Korean chicken farms. Results An overall prevalence of 75% (291/388) was found. Positive farms contained several Eimeria species (mean = 4.2). Of the positive samples, E. acervulina (98.6%), E. maxima (84.8%), and E. tenella (82.8%) were the most prevalent species. Compared with cage-fed chickens, broilers and native chickens reared in free-range management were more at risk of acquiring an Eimeria infection. Sensitivities to six anticoccidial drugs (clopidol, diclazuril, maduramycin, monensin, salinomycin, and toltrazuril) were tested using nine field samples. Compared with untreated healthy control chickens, the body weight gains of infected chickens and treated/infected chickens were significantly reduced in all groups. Fecal oocyst shedding was significantly reduced in four clopidol-treated/infected groups, three diclazuril-treated/infected groups, two toltrazuril-treated/infected groups, one monensin-treated/infected group, and one salinomycin-treated/infected group, compared with the respective untreated/infected control groups. Intestinal lesion scores were also reduced in three clopidol-treated/infected groups, one monensin-treated/infected group, and one toltrazuril-treated/infected group. However, an overall assessment using the anticoccidial index, percent optimum anticoccidial activity, relative oocyst production, and reduced lesion score index found that all field samples had strong resistance to all tested anticoccidial drugs. Conclusion The results of this large-scale epidemiological investigation and anticoccidial sensitivity testing showed a high prevalence of coccidiosis and the presence of severe drug resistant Eimeria species in the field. These findings will be useful for optimizing the control of coccidiosis in the poultry industry.

Prevalence and diversity of Eimeria spp. in free-range chickens in northeastern Brazil

“…The presence of mixed infections was observed on 57 farms, with infections by two to five species per farm. According to Flores et al ( 31 ), the high prevalence and diversity, associated with indiscriminate use of anticoccidials are responsible for severe drug resistant Eimeria species in Korean chicken farms. Mixed infection, according to Fatoba et al ( 25 ), is very common: it causes increased pathogenicity and is a threat to vaccine control.…”

Molecular Investigation of Eimeria Species in Broiler Farms in the Province of Vojvodina, Serbia

“…By applying molecular techniques, the limitations of the morphometric method can be bypassed, and it is not necessary to euthanise chickens for necropsy and estimation of lesion score [7,27]. The PCR technique can identify Eimeria species that are present on the farm [10,28], which can help in the prevention and control of the disease. PCR methods are used for Eimeria species determination due to the high specificity and sensitivity of this assay.…”

“…However, the emergence of resistant species of Eimeria reduced the effectiveness of anticoccidial drugs. Over time, coccidia has developed resistance to coccidiostats [10]. Resistant Eimeria species are the main cause of subclinical coccidiosis (decrease in body weight of chickens, poor feed conversion) and increasing production costs.…”

“…Due to increasing demand for poultry meat and eggs, industrial poultry production is often faced with a high density on chickens on farms, which increases the possibility of persistence of this parasitosis [10]. Epidemiological research and identification of Eimeria species play an important role in prevention and control of coccidiosis.…”

Effect of zinc hydroxychloride supplementation combined with an anticoccidial drug on Eimeria tenella infection in broiler chickens

“…Coccidiosis in poultry is controlled using anticoccidial drugs such as sulfaquinoxaline, clopidol, nicarbazin, narasin, monensin, salinomycin, amprolium + ethopabate, and diclazuril. The most serious limitation to the drugs' effectiveness is the development of resistance [4][5][6]. Therefore, many studies have used alternative methods, such as plant extracts, vitamins, and minerals, to control and treat the disease [7][8][9].…”