Small-scale spatial analysis of intermediate and definitive hosts of Angiostrongylus cantonensis

Background:Angiostrongyliasis is a food-borne parasitic zoonosis.Human infection is caused by infection with the third-stage larvae of Angiostrongylus cantonensis.The life cycle of A.cantonensis involves rodents as definitive hosts and molluscs as intermediate hosts.This study aims to investigate on the infection status and characteristics of spatial distribution of these hosts,which are key components in the strategy for the prevention and control of angiostrongyliasis.Methods:Three villages from Nanao Island,Guangdong Province,China,were chosen as study area by stratified random sampling.The density and natural infection of Pomacea canaliculata and various rat species were surveyed every three months from December 2015 to September 2016,with spatial correlations of the positive P.canaliculata and the infection rates analysed by ArcGIS,scan statistics,ordinary least squares(OLS)and geographically weighted regression(GWR)models.Results:A total of 2192 P.canaliculata specimens were collected from the field,of which 1190 were randomly chosen to be examined for third-stage larvae of A.cantonensis.Seventy-two Angiostrongylus-infected snails were found,which represents a larval infection rate of 6.1%(72/1190).In total,110 rats including 85 Rattus norvegicus,10 R.flavipectus,one R.losea and 14 Suncus murinus were captured,and 32 individuals were positive(for adult worms),representing an infection rate of 29.1%of the definitive hosts(32/110).Worms were only found in R.norvegicus and R.flavipectus,representing a prevalence of 36.5%(31/85)and 10%(1/10),respectively in these species,but none in R.losea and S.murinus,despite testing as many as 32 of the latter species.Statistically,spatial correlation and spatial clusters in the spatial distribution of positive P.canaliculata and positive rats existed.Most of the spatial variability of the host infection rates came from spatial autocorrelation.Nine spatial clusters with respect to positive P.canaliculata were identified,but only two correlated to infection rates.The results show that corrected Akaike information criterion,R2,R2 adjusted andσ2 in the GWR model were superior to those in the OLS model.Conclusions:P.canaliculata and rats were widely distributed in Nanao Island and positive infection has also been found in the hosts,demonstrating that there was a risk of angiostrongyliasis in this region of China.The distribution of positive P.canaliculata and rats exhibited spatial correlation,and the GWR model had advantage over the OLS model in the spatial analysis of hosts of A.cantonensis.

Dynamic RNA profiles in the small intestinal epithelia of cats after Toxoplasma gondii infection

Background Felids are the only definitive hosts ofToxoplasma gondii. However, the biological features of the feline small intestine followingT. gondii infection are poorly understood. We investigated the changes in the expression of RNAs (including mRNAs, long non-coding RNAs and circular RNAs) in the small intestinal epithelia of cats followingT. gondii infection to improve our understanding of the life cycle ofT. gondii and cat responses toT. gondii infection.Methods Fifteen cats were randomly assigned to five groups, and the infection groups were inoculated with 600 tissue cysts of theT. gondii Pru strain by gavage. The small intestinal epithelia of cats were collected at 6, 10, 14, and 30 days post infection (DPI). Using high-throughput RNA sequencing (RNA-seq), we investigated the changes in RNA expression. The expression levels of differentially expressed (DE) genes and non-coding RNAs (ncRNAs) identified by RNA-seq were validated by quantitative reverse transcription PCR (qRT-PCR). Differential expression was determined using the DESeq R package.Results In total, 207 annotated lncRNAs, 20,552 novel lncRNAs, 3342 novel circRNAs and 19,409 mRNAs were identified. Among these, 70 to 344 DE mRNAs, lncRNAs and circRNAs were detected, and the post-cleavage binding sites between 725 ncRNAs and 2082 miRNAs were predicted. Using the co-location method, we predicted that a total of 235 lncRNAs target 1044 protein-coding genes, while the results of co-expression analysis revealed that 174 lncRNAs target 2097 mRNAs. Pathway enrichment analyses of the genes targeted by ncRNAs suggested that most ncRNAs were significantly enriched in immune or diseases-related pathways. NcRNA regulatory networks revealed that a single ncRNA could be directly or indirectly regulated by multiple genes or ncRNAs that could influence the immune response of cats. Co-expression analysis showed that 242 circRNAs, mainly involved in immune responses, were significantly associated withT. gondii infection. In contrast, 1352 protein coding RNAs, mainly involved in nucleic acid process/repair pathways or oocyte development pathways, were negatively associated withT. gondii infection.Conclusions This study is the first to reveal the expression profiles of circRNAs, lncRNAs and mRNAs in the cat small intestine followingT. gondii infection and will facilitate the elucidation of the role of ncRNAs in the pathogenesis ofT. gondii infection in its definitive host, thereby facilitating the development of novel intervention strategies againstT. gondii infection in humans and animals.

Deworming of stray dogs and wild canines with praziquantel-laced baits delivered by an unmanned aerial vehicle in areas highly endemic for echinococcosis in China

Background:Canines,the definitive hosts for the parasites causing alveolar(AE)and cystic echinococcosis(CE),are the main source of this infections playing the key role in the transmission.The ten-year mortality rate of AE is extremely high(94%)if the patients are not given sustained treatment.The aim of this field study is to explore the possibility of delivery of praziquantel-laced baits using unmanned aerial vehicles(UAVs)aimed at deworming wild canines in the endemic areas.Methods:UAVs were compared to manual bait delivery in the 1-km^(2)test areas followed by testing of canine faeces using an Echinococcus coproantigen ELISA test in the ensuing year.The outcomes of the two approaches were compared with respect to time of delivery and overall cost.Findings:Compared to manual bait delivery,delivery by UAVs saved up to 67%of the overall cost.Three times more staff was needed for the former approach compared to the latter and,time wise,UAV bait delivery saved 350%compared to manual bait delivery on average.With regard to investment needed,the use of UAVs showed an efficiency 2.5 times better than manual bait delivery.Compared to the area served by UAVs,the average positive rate for the canine faecal samples was more than 38%higher in the area served manually.Conclusion:The technique of bait delivery with praziquantel using UAVs for canine deworming has a strong potential with regard to savings of manpower,time and overall cost in areas highly endemic for echinococcosis.