Investigation Of Neoschoengastia Gallinarum Infection In Chickens And The Study Of Drug Screening And Application

The larva of Neoschoengastia gallinarum feed on the blood of many species of birds and poultries,primarily parasitizing the underarm and medial side of the thigh,and when fall off of the host they develop into nymph.N.gallinarum is widely distributed throughout China.The diseases caused by N.gallinarum are primarily detected from March to December,but they peak from June to October.Poultry is at a high risk of N.gallinarum infection,and chickens have strong tissue responses following parasitization.The primary clinical symptoms of N.gallinarum infection are anemia,emaciation,mental retardation,and even death if infected with a large population.The poultry industry is changing into a modern sales model of unified slaughtering,uniform freezing and unified sales.However,the incidence of N.gallinarum has been increasing.If a wound on the body surface of a chicken is not completely cured before being sold,the wound will severely reduce the value of the chicken products.In this study,N.gallinarum infections in Guangdong,Guangxi,Hunan,Hubei,Fujian,Zhejiang and Jiangsu provinces were investigated,the N.gallinarum samples were identified by morphological and molecular methods,and the pevalence was summarized.In addition,the ability of different types of chemical drugs and plant extracts to kill N.gallinarum in vitro was tested in the laboratory,which provided the basis for the prevention and control of mites in actual production.Finally,comprehensive drug prevention and control strategies were proposed and verified their effectiveness was verified by clinical experiments.This study lays a foundation for the prevention and control of N.gallinarum using plant extractions,and provides comprehensive strategies for the clinical use of drugs.The incidence of N.gallinarum on chicken farms belonging to Wen's Group Co.,Ltd in Guangdong,Guangxi,Fujian,Hunan,Hubei,Zhejiang and Jiangsu provinces,were investigated and counted from June to October,2017.The data were analyzed based on region,attack time,chicken species and age.Guangdong province and Guangxi province were the regions with the most severe incidences,with 174 cases in Guangdong province and 137 in Guangxi province.The climatic environment was characterized by high average temperatures and humidity throughout the year for both of these provinces,which may promote the spread of N.gallinarum.The chicken farms are generally built in vegetation rich mountain forests that provide good conditions for the life cycle of N.gallinarum.The next most affected region was Fujian Province,with 69 cases found in four months.Fujian borders Guangdong,and the sampling site is in the south of Fujian province,which is closed to Guangdong,and has a similar climate and environment.The clinical symptoms caused by N.gallinarum in chickens from the Hunan,Hubei,Zhejiang and Jiangsu regions were relatively mild,and the incidence was reduced.Morphological and molecular biological identification of N.gallinarum was performed.The unstained glass slides of N.gallinarum were made using Hershey's solution for easy observation using a microscope.All parts of the parasite sample were identified by referring to the reported identification formula of N.gallinarum,and the results showed that the findings are consistent.Molecular biological identification of N.gallinarum was further performed,and the corresponding sequences were amplified successfully with 2 pairs of conservative primers.The comparison revealed that the sequences of isolated parasite samples were more than 75% similar to those species of families Neoschoengastia and Ascoschoengastia published on the Internet.The corresponding sequences of N.gallinarum were reported for the first time in this study.Plant extracts were prepared,and 12 types of chemical drugs sold on the market were used to test their efficacy for killing N.gallinarum in vitro.Live specimens of N.gallinarum were observed under a stereomicroscope.In the plant extract groups,5 g of each herb was extracted,and then diluted with 10 mL solution.Each herb was test in triplicate.In the chemical drug group,the drugs were diluted to 1: 600,1: 1000,1: 1500 and 1: 2000,and each dilution was tested in triplicate.In each repeat group,five live N.gallinarum parasites were used to test each drug.The time of death was recorded and considered valid only when the parasite did not move following a needle prick.The experimental results of the plant extract group showed that the mite-killing times for the tested traditional Chinese medicines were 0.3 h for Eugenia caryophyllata Thunb.,0.6 h for leaves of Artemesia annua,1 h for Kochia scoparia(L.)Schrad.,1.5 h for Elsholtzia ciliata(Thunb.)Hyland.,1.5 h for Pinus massoniana Lamb.,1.2 h for Kadsurae caulis,2 h for Stellera chamaejasme L.,2 h for Artemisiacapillaris Thunb,2.5 h for leaves of Eucalyptus robusta Smith,3 h for Mentha arvensis and 4 h for Kochia scoparia(L.)Schrad.These 11 drugs were effective at repelling N.gallinarum.The shortest acaricidal times in the chemical drug group were 5 min for 2,2-dichlorovinyldimethyl phosphate,5 min for 15% pyridaben,6.5 h for phoxim,7 h for amitraz,16 h for Matrine and 17 h for Dipterex.The other chemical drugs took too long to kill the mites and therefore had no practical value.Finally,three chicken farms were selected to examine three different schemes for the prevention and control of N.gallinarum.The first scheme used ivermectin as an oral therapy,and 15% pyridaben and 40% phoxim were sprayed on chicken coops and sports grounds every seven days,and mats were sprinkled with sulphur powder.The results showed that the infection rate of N.gallinarum was decreased,and no new wounds caused by N.gallinarum were found,but the disadvantages of this scheme were that infections easily recurred after drug withdrawal,the workload increased heavily,and the drugs were expensive.The second scheme was to spray the sports fields and chicken coops with 15% pyridaben for four consecutive days.The results showed that the infection rate of N.gallinarum was reduced by 34% and no new wounds were found.The disadvantage of this scheme was that the infections also easily recurred after drug withdrawal,and N.gallinarum might develop drug resistance to pyridaben.The third scheme was to spread the mixed litter of Artemisia lanceolata in the chicken coops,and the effect was good.The infection rate was reduced by 28% after seven days,but one new case occurred.The disadvantage of this scheme was that the effect of anti-mite is not as good as that of chemical drugs,but A.lanceolata could be used over the long term.