Liver flukes belonging to the genusFasciolaare among the causes of foodborne diseases of parasitic etiology. These parasites cause significant public health problems and substantial economic losses to the livestock industry. Therefore, it is important to definitively characterize theFasciolaspecies. Current phenotypic techniques fail to reflect the full extent of the diversity ofFasciolaspp. In this respect, the use of molecular techniques to identify and differentiateFasciolaspp. offer considerable advantages. The advent of a variety of molecular genetic techniques also provides a powerful method to elucidate many aspects ofFasciolabiology, epidemiology, and genetics. However, the discriminatory power of these molecular methods varies, as does the speed and ease of performance and cost. There is a need for the development of new methods to identify the mechanisms underpinning the origin and maintenance of genetic variation within and amongFasciolapopulations. The increasing application of the current and new methods will yield a much improved understanding ofFasciolaepidemiology and evolution as well as more effective means of parasite control. Herein, we provide an overview of the molecular techniques that are being used for the genetic characterization, detection and genotyping ofFasciolaspp..

Cryptosporidium parvum is a zoonotic intracellular protozoan responsible for the diarrheal illness cryptosporidiosis in humans and animals. Although a number of zoite surface proteins are known to be expressed during, and believed to be involved in, attachment and invasion of host cells, the molecular mechanisms by which C. parvum invades the host epithelial cells are not well understood. In the present study, we investigated the gene expression patterns, protein localization in developmental stages in culture, and in vitro neutralization characteristics of Cpgp40/15 and Cpgp40. Indirect immunofluorescence assay showed that Cpgp40/15 is associated with the parasitophorous vacuole membrane (PVM) during intracellular development. Both anti-gp40/15 and anti-gp40 antibodies demonstrated the ability to neutralize C. parvum infection in vitro. Further studies are needed to fully understand the specific role and functional mechanism of Cpgp40/15 (or gp40/15 complex) in the invasion of the host or in the PVM and to determine the feasibility of gp40/15 as a vaccine candidate for cryptosporidiosis in vivo.

Poultry necrotic enteritis (NE) is a complex and multifactorial disease caused by Clostridium perfringens types. Earlier, the disease was prevented and/or controlled through the addition of in-feed antibiotics and antimicrobial growth promoters (AGPs). The ban on the use of these agents as feed additives has been a major reason for re-emergence of this disease leading to huge economic losses to the world poultry industry. Understanding the pathogenesis of NE by developing an effective experimental model remains challenging and lacks consistency owing to the involvement of several critical factors involved in causing lesions of disease in the field. In this study, locally characterized C. perfringens types, i.e., ACP (toxinotype A), and GCP (toxinotype G), obtained from NE outbreaks on commercial farms in China (2020–2022), were used to experimentally induce NE in Specific-Pathogen-Free (SPF) chicks. The lesion scores observed on day 20 were 1.9 ± 1.10 (GCP strain) and 1.5 ± 1.08 (ACP strain), and both had significant difference as compared to the control group. The inclusion of fishmeal in addition to oral clostridial dose, i.e., fishmeal (day 7 onward) + Clostridia (7.5 × 10⁸ cfu/mL consecutively for 04 days) induced a lesion score of 2.0 ± 1.15 in respective groups. Use of coccidia (Eimeria necatrix) on day 9 followed by clostridia challenge enhanced the lesion scores to 2.5 ± 1.08 and 2.2 ± 1.23 for type G and type A strains, respectively. When both predisposing factors (coccidia + fish meal) were given together, i.e., fishmeal (day 7 onward) and coccidia (day 9) along with clostridia, the lesion scores were 3.2 ± 1.22 (GCP + coccidia + fish meal) and 3.0 ± 1.15 (ACP + coccidia + fish meal). These results were significantly different from group 1 (ACP) and 2 (GCP), in which only C. perfringens was used to induce NE. The clinical signs as well as histopathological lesions in experimentally induced groups were found similar as reported in the literature. The two type G strains identified in this study were also used for susceptibility testing against various drugs. Both strains were found to be resistant to amikacin, doxycycline, metronidazole, neomycin, nystatin, polymyxin B, streptomycin, and tetracycline. Variable susceptibility was seen against ceftriaxone, florfenicol, gentamicin, and kanamycin drugs. Amoxicillin, ampicillin, cefotaxime, ciprofloxacin, enrofloxacin, ofloxacin, and penicillin were effective drugs based upon their low level of resistance and therefore they might be preferred over other antimicrobial agents for proper treatment/prophylaxis of NE infections. Further studies are needed to study the pathogenesis of NE in detail in experimentally induced models along with continuous monitoring of the resistance pattern of C. perfringens strains in the field.

Cryptosporidium is a genus of protozoan parasites that infect the gastrointestinal epithelium of a variety of vertebrate hosts. Intestinal epithelial cells are the first line of defense and play a critical role in orchestrating host immunity against Cryptosporidium infection. To counteract host defense response, Cryptosporidium has developed strategies of immune evasion to promote parasitic replication and survival within epithelial cells, but the underlying mechanisms are largely unclear. Using various models of intestinal cryptosporidiosis, we found that Cryptosporidium infection caused suppression of mitogen-activated protein kinase (MAPK) signaling in infected murine intestinal epithelial cells. Whereas expression levels of most genes encoding the key components of the MAPK signaling pathway were not changed in infected intestinal epithelial cells, we detected a significant downregulation of p38/Mapk, MAP kinase-activated protein kinase 2 (Mk2), and Mk3 genes in infected host cells. Suppression of MAPK signaling was associated with an impaired intestinal epithelial defense against C. parvum infection. Our data suggest that cryptosporidial infection may suppress intestinal epithelial cell MAPK signaling associated with the evasion of host antimicrobial defense.

Epizootic hemorrhagic disease (EHD) is an infectious viral disease caused by epizootic hemorrhagic disease virus (EHDV) and EHDV frequently circulates in wild and domestic ruminants. Sporadic outbreaks of EHD have caused thousands of deaths and stillbirths on cattle farms. However, not much is known about the circulating status of EHDV in Guangdong, southern China. To estimate the seroprevalence of EHDV in Guangdong province, 2886 cattle serum samples were collected from 2013 to 2017 and tested for antibodies against EHDV using a competitive ELISA. The overall seroprevalence of EHDV reached 57.87% and was highest in autumn (75.34%). A subset of positive samples were serotyped by a serum neutralization test, showing that EHDV serotypes 1 and 5–8 were circulating in Guangdong. In addition, EHDV prevalence always peaked in autumn, while eastern Guangdong had the highest EHDV seropositivity over the five-year period, displaying apparent temporal–spatial distribution of EHDV prevalence. A binary logistic model analysis indicated a significant association between cattle with BTV infections and seroprevalence of EHDV (OR = 1.70, p < 0.001). The co-infection of different serotypes of EHDV and BTV raises a high risk of potential genomic reassortment and is likely to pose a significant threat to cattle, thus urging more surveillance to monitor their circulating dynamics in China.

Background: Cryptosporidium is one of the most prevalent parasites infecting both birds and mammals. To examine the prevalence of Cryptosporidium species and evaluate the public health significance of domestic chickens in Guangdong Province, southern China, we analyzed 1001 fecal samples from 43 intensive broiler chicken farms across six distinct geographical regions. Methods: Individual DNA samples were subjected to nested PCR-based amplification and sequencing of the small subunit of the nuclear ribosomal RNA gene (SSU rRNA). Analysis of the 60 kDa glycoprotein gene (gp60) was performed to characterize the subtypes of C. meleagridis. Results: The overall prevalence of Cryptosporidium was 13.2% (95% CI 11.1–15.3) (24 of 43 farms), with C. meleagridis (7.8%), C. baileyi (4.8%) and mixed infections (0.6%). Using the gp60 gene, three subtype families, IIIb, IIIe and IIIg, were identified, including six subtypes: one novel (IIIgA25G3R1a) and five previously reported (IIIbA23G1R1c, IIIbA24G1R1, IIIbA21G1R1a, IIIeA17G2R1 and IIIeA26G2R1). Within these subtypes, five known subtypes were genetically identical to those identified in humans. Conclusions: This is the first report of C. meleagridis in chickens from Guangdong. The frequent occurrence of C. meleagridis in domestic chickens and the common C. meleagridis subtypes identified in both humans and chickens is of public health significance. Our study indicates that broiler chickens represent a potential zoonotic risk for the transmission of Cryptosporidium in this region. Graphical