Subtypes of Cryptosporidium spp. in mice and other small mammals

DNA sequence analysis of the 60 kDa glycoprotein (gp60) gene has been used extensively in subtyping Cryptosporidium hominis in humans and Cryptosporidium parvum in humans and ruminants. In this study, nucleotide sequences of the gp60 gene were obtained from seven Cryptosporidium species and genotypes related to the two species. Altogether, seven subtype families were detected, including four new subtype families. These data should be useful in studies of the transmission and zoonotic potential of cryptosporidiosis in mice and small wild mammals.     

Bovine sarcocystosis: Sarcocystis species,diagnosis, prevalence,economic and public health considerations,and association of Sarcocystis species with eosinophilic myositis in cattle

Infections by Sarcocystis in cattle are ubiquitous worldwide. There is considerable debate concerning the identity of Sarcocystis spp. in cattle. Proper diagnosis of Sarcocystis spp. is important to assess their economic and public health importance. Currently there are seven named species: Sarcocystis hirsuta, Sarcocystis cruzi, Sarcocystis hominis, Sarcocystis bovifelis, arcocystis heydorni, Sarcocystis bovini and Sarcocystis rommeli. Additionally, there are unnamed Sarcocystis spp. Two species, S. hominis and S. heydorni, are zoonotic. One out of seven species (S. hirsuta, contracted from cats) forms macroscopic cysts which can be visible during carcass inspection. Current molecular characterization is based on DNA extracted from sarcocysts from naturally infected cattle because DNA was not characterized from tissues of experimentally infected cattle or feces of experimentally infected definitive hosts. Sarcocystis cruzi (transmitted via canids) is recognized as the most pathogenic species and it causes abortion, low milk yield, poor body growth, and outbreaks of clinical sarcocystosis and death. Additionally, Sarcocystis infections have been linked to an inflammatory condition of striated muscles termed bovine eosinophilic myositis (BEM). Cattle affected by BEM appear clinically normal. Diagnosis of BEM at slaughter occurs when inspecting the carcass surface, or once the carcass has been divided into prime cuts or quarters. Sex and breed have no apparent influence on prevalence of BEM. The condition evidently occurs with equal frequency in steers, cows, and heifers. Virtually all striated muscles can be affected including skeletal muscles, the muscles of the eye, larynx, and the heart. In the USA, regulations require condemnation of BEM-affected parts, or (in severe cases) the entire carcass. These aesthetic considerations result in economic losses. Cattle experimentally infected with Sarcocystis did not have BEM at slaughter. Here, we review the status of Sarcocystis spp. and BEM in cattle including prevalence, lesions, epidemiology, and association of BEM with different species of Sarcocystis.     

The importance of being short: the role of rabies virus phosphoprotein isoforms assessed by differential IRES translation initiation

The rabies virus (RV) phosphoprotein P is a multifunctional protein involved in viral RNA synthesis and in counteracting host innate immune responses. We have previously shown that RV P gene expression levels can be regulated by using picornavirus internal ribosome entry site (IRES) elements. Here we exploited a particular feature of the foot-and-mouth disease virus (FMDV) IRES, namely, preferential initiation at a downstream initiation codon, to address the role of N-terminally truncated RV phosphoproteins usually generated in RV-infected cells through ribosomal leaky scanning. Recombinant RVs in which P synthesis was directed by the poliovirus or FMDV IRES produced full-length P (P1) or a truncated form (P2), as the dominant product, respectively. While the P2 overexpressing virus showed attenuated growth in interferon-incompetent cells, it was superior to the P1 overexpressing virus in preventing expression of host interferon-stimulated genes. This indicates that in RV infected cells the availability of the truncated P2 protein is critical for viral resistance to interferon.     

我国人与犬、猫共患病防控存在的主要问题与对策建议

随着社会经济的发展、城市化进程的加速及人们生活水平的不断提高,越来越多的宠物走进了人们的家庭,在人类社会生活中发挥了积极作用。但同时,宠物也是人兽共患病的重要传染源和传播媒介。与人类关系最为密切的犬、猫在人兽共患病的防控中具有重要的意义。在已报道的200多种主要的人兽共患病中,与宠物犬、猫有直接或间接关系的有70余种。随着宠物犬猫数量的大幅攀升和宠物业的飞速发展,我国人与犬猫共患病可能会出现逐步高发的趋势,疫病防控工作面临着许多问题。为了完善宠物管理制度,建立有效的防疫监督体系,对人与犬猫共患病实行有效的防控,本文就完善法律法规、形成综合管理机制,加强卫生监督、强化无害化处理、培养专业人才以及广泛开展宣传教育等6个方面提出了相关建议。     

Molecular epidemiology of cryptosporidiosis: An update

Molecular tools have been developed to detect and differentiate Cryptosporidium at the species/genotype and subtype levels. These tools have been increasingly used in characterizing the transmission of Cryptosporidium spp. in humans and animals. Results of these molecular epidemiologic studies have led to better appreciation of the public health importance of Cryptosporidium species/genotypes in various animals and improved understanding of infection sources in humans. Geographic, seasonal and socioeconomic differences in the distribution of Cryptosporidium spp. in humans have been identified, and have been attributed to differences in infection sources and transmission routes. The transmission of C. parvum in humans is mostly anthroponotic in developing countries, with zoonotic infections play an important role in developed countries. Species of Cryptosporidium and subtype families of C. hominis have been shown to induce different clinical manifestations and have different potential to cause outbreaks. The wide use of a new generation of genotyping and subtyping tools in well designed epidemiologic studies should lead to a more in-depth understanding of the epidemiology of cryptosporidiosis in humans and animals.     

Review: SARS-CoV-2 infection in farmed minks – an overview of current knowledge on occurrence,disease and epidemiology

Coronaviruses (CoVs), which are enveloped, positive-sense RNA viruses, may cause infections in mammals and birds. Apart from the respiratory manifestations, CoVs are also responsible for infections of the gastrointestinal tract and nervous systems. Their propensity to recombine allows them to easily transmit and adapt to new hosts. The emergence of a new CoV in humans, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is attributed to a zoonotic origin, has provoked numerous studies to assess its pathogenicity for different animal species (pets, farm and wild animals). Available results indicate that numerous animal species are susceptible to infection with SARS-CoV-2. From April 2020, when the first SARS-CoV-2 infection in minks was reported in the Netherlands, to the end of January 2021, further outbreaks have been confirmed in Denmark, Italy, Spain, Sweden, the United States, Greece, France, Canada, Lithuania and Poland. It has also been established that human-to-minks and minks-to-human transmission may occur. The results obtained to date indicate that the virus was originally introduced into the minks population by humans, possibly at the start of the pandemic and had been circulating in the population for several weeks before detection. Recent data indicate that minks are highly susceptible to SARS-CoV-2 infection, but the route or routes of virus transmission between farms, other than by direct contact with infected humans, have not been identified. In minks, infection can occur in clinical and subclinical form, making it possibly difficult to detect. Therefore, minks could represent potentially dangerous, not always recognized, animal reservoir for SARS-CoV-2. The current data indicate that further studies on minks and other Mustelidae are needed to clarify whether they may be a potential reservoir for SARS-CoV-2, and if so, how and whether this can be prevented.     

Population genetics of Cryptosporidium meleagridis in humans and birds: evidence for cross-species transmission

Population genetic studies have been used to understand the transmission of pathogens in humans and animals, especially the role of zoonotic infections and evolution and dispersal of virulent subtypes. In this study, we analysed the genetic diversity and population structure of Cryptosporidium meleagridis, the only known Cryptosporidium species that infects both avian and mammalian hosts and is responsible for approximately 10% of human cryptosporidiosis in some areas. A total of 62 C. meleagridis specimens from children, AIDS patients, and birds in Lima, Peru were characterised by sequence analysis of the ssrRNA gene and five minisatellite, microsatellite and polymorphic markers in chromosome 6, including the 60 kDa glycoprotein (gp60), 47 kDa glycoprotein (CP47), a serine repeat antigen (MSC6-5), retinitis pigmentosa GTPase regulator (RPGR) and thrombospondin protein 8 (TSP8). The multilocus sequence analysis identified concurrent infections with Cryptosporidium hominis in four AIDS patients and three children. Unique subtypes of C. meleagridis ranged from eight at the gp60 locus (gene diversity –Hd = 0.651), three at the RPGR (Hd = 0.556), three at the MSC6-5 locus (Hd = 0.242), two at TSP8 (Hd = 0.198), to one at CP47 (monomorphic), much lower than that of C. hominis in the same area. Intragenic linkage disequilibrium was strong and complete at all gene loci. Intergenic linkage disequilibrium was highly significant (P < 0.001) for all pairs of polymorphic loci. Two major groups of subtypes were seen, with most subtypes belonging to group 1. Within group 1, there was no clear population segregation, and two of the 14 multilocus subtypes of C. meleagridis were found in both AIDS patients and birds. We believe that these results provide the first evidence of a clonal population structure of C. meleagridis and the likely occurrence of cross-species transmission of C. meleagridis between birds and humans.     

土拉弗朗西斯菌检测研究进展

土拉弗朗西斯菌（Francisella tularensis）是土拉菌病（Tularemia）的致病菌,是最具传染性的致病菌之一,在自然界中已发现一百种以上的动物感染此菌。因其传播途径多样,易扩散、毒性强而被美国疾病控制预防中心列入A类生物恐怖制剂。土拉菌病是一种人畜共患病,致死率高,及时、准确的检测土拉菌对于土拉菌病患者及时治疗和防止扩散具有重要的意义。土拉菌检测方法很多,如菌培养,微凝集实验、酶联免疫吸附、快速检测试纸条、生物传感器、PCR、核酸杂交检测、质谱分析、基因芯片等。但到目前为止还没有一种成熟的用于土拉菌检测方法,其主要原因在于土拉菌致病性强,且不易分离培养。本文综述了土拉菌细菌学、免疫学、分子生物学方法检测的最新研究进展。     

Cryptosporidium in wild placental mammals

Cryptosporidium species are common parasites of wild placental mammals. Recent parasitological studies combined with molecular genotyping techniques have been providing valuable new insight into the host specificity and potential transmission of various Cryptosporidium species/genotypes among animals and between these animals and humans. Although Cryptosporidium in wild animals may possess a potential public health problem due to oocyst contamination in the environment, studies at various regions of the world have indicated a strong host-adaptation by these parasites and a limited potential of cross-species transmission of cryptosporidiosis among placental mammals, suggesting that these animals are probably not a major reservoir for human infection. However, Cryptosporidium species/genotypes in placental animals have been reported occasionally in humans. Therefore, public health significance of some Cryptosporidium species in wild placental mammals, such as the cervine genotype, should not be overlooked and should be further studied.     

宠物重要人兽共患病毒病

随着人们生活水平的不断提高,城市家庭饲养宠物日益增多,宠物已经成为人们日常生活中接触最多的动物。然而,许多宠物是人兽共患疾病的重要传染源,随着人类与各种动物间＂零＂距离的接触,各种宠物携带的人兽共患病也悄然传入人类,给人们身体健康和公共卫生安全带来了严重的威胁。近年来,许多学者对犬、猫、鸟、鼠和其他宠物易感的人兽共患病毒病开展了许多研究工作,本文对狂犬病、戊型肝炎、禽流感、淋巴细胞脉络膜脑膜炎、流行性出血热、西尼罗热等一些严重危害的宠物人兽共患病毒病进行了概述。