Diarrheal diseases caused by intestinal protozoan parasites are a major food-borne public health problem across the world. Vegetables and fruits provide important nutrients and minerals, but are also common sources of some food-borne human pathogenic microorganisms. The contamination of raw vegetables and fruits with human pathogenic parasites are now a global public health threat, despite the health benefits of these foods in non-pharmacological prophylaxes against diseases. A large number of reports have documented the contamination of vegetables or fruits with human pathogenic microorganisms. In this paper, we reviewed the contamination and detection methods of human pathogenic intestinal protozoans that are frequently recovered from raw vegetables and fruits. The protozoan parasites include Cryptosporidium spp., Giardia duodenalis, Cyclospora cayetanensis, Entamoeba spp., Toxoplasma gondii, Balantioides coli, Blastocystis sp., Cystoisospora belli and Enterocytozoon bieneusi. The risk factors involved in the contamination of vegetables and fruits with parasites are also assessed.

Cryptosporidium spp. and Giardia duodenalis are important gastrointestinal protists in humans and animals worldwide. In China, bovine cryptosporidiosis and giardiasis are of increasing concern because cattle are important reservoirs of these parasites, which have become potential threats to public health and to large numbers of cattle in recent years. A total of 1366 fecal samples from the Ningxia Autonomous Region were examined. The overall infection rates for Cryptosporidium spp. and G. duodenalis were 1.61% and 2.12%, respectively. Cryptosporidium was only detected in preweaned calves and adults older than 2 years, whereas G. duodenalis was only detected in calves aged less than 11 months. Cryptosporidium spp. were characterized with a PCR–restriction fragment length polymorphism analysis and DNA sequence analysis of the small subunit rRNA gene. Three Cryptosporidium species were identified: C. parvum (n = 15) and C. bovis (n = 4) in preweaned calves, and C. andersoni (n = 4) in adults aged over 2 years. A DNA sequence analysis of the gp60 gene suggested that the 15 C. parvum isolates all belonged to subtype IIdA15G1. Twenty-nine G. duodenalis isolates were analyzed by DNA sequencing of the triosephosphate isomerase (tpi) and glutamate dehydrogenase (gdh) genes. Two G. duodenalis assemblages were identified, assemblages E (n = 15) and B (n = 4, one subtype B1 and three subtype B2) in preweaned calves, and assemblage E (n = 10) in 3–11-month-old calves. The predominance of C. parvum detected in preweaned calves and the first identified subtype IIdA15G1 in dairy cattle, and the dominant G. duodenalis assemblage E in this study differed considerably from those found in Henan, Heilongjiang, and Shannxi Provinces. Our findings further confirm the dominance of C. parvum IId subtypes in China.

Enterocytozoon bieneusi is the most frequently diagnosed microsporidian species in humans and a wide range of animals. This study was conducted to assess the prevalence and molecular characteristics of E. bieneusi in dairy cattle in Henan Province of central China and the Ningxia Hui Autonomous Region of northwest China. Of 879 fresh fecal specimens, 24.3 % (214/879) tested positive for E. bieneusi by nested polymerase chain reaction (PCR) based on the internal transcriber spacer (ITS) gene. The highest infection rate, 46.8 % (51/109, P < 0.0001), was observed in a group of dairy cattle with diarrhea, located in Ningxia. The age groups with higher infection rates were pre-weaned calves (29.3 %, 127/434, P < 0.0001) and post-weaned calves (23.9 %, 63/264, P = 0.006). Sequencing and phylogenetic analysis revealed 20 E. bieneusi ITS genotypes (15 known and five new), including members of Group 1 and Group 2. Genotypes I and J were detected in 64.5 % (138/214) of the E. bieneusi positive specimens. Genotypes I and J were the dominant genotypes in dairy cattle in the present study. The detection of zoonotic genotypes of E. bieneusi in dairy farms indicates that cattle may play an important role as a reservoir host for zoonotic infections.

Cryptosporidium spp. are zoonotic parasites responsible for diarrhoeal diseases in animals and humans worldwide. Cattle are the most common mammalian species in which Cryptosporidium is detected, with pre-weaned calves considered to be reservoirs for zoonotic C. parvum. In October 2013, severe diarrhoea was observed in 396 pre-weaned calves at a farm in the Ningxia Autonomous Region of Northwestern China. 356 of the infected calves died despite antibiotic therapy. 252 faecal samples were collected from the investigated farm. The identity of Cryptosporidium species was determined by polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) analysis, and by DNA sequence analysis of the small subunit (SSU) rRNA gene. C. parvum was subtyped using sequence analysis of the 60 kDa glycoprotein (gp60) gene. The highest infection rate of 83.3% (40/48) was seen in 2–3-week-old calves with diarrhoea, corresponding to the age at which animals died. Three Cryptosporidium species were identified, including C. parvum (n = 51), C. bovi s (n = 1), and C. ryanae (n = 1). All C. parvum isolates were further identified as subtype IIdA15G1. Cryptosporidium parvum was likely to be most responsible for diarrhoea and death. This is the first report of a cryptosporidiosis outbreak caused by C. parvum IIdA15G1 in Chinese dairy cattle.

Cryptosporidium spp. and Giardia duodenalis are important causes of diarrheal diseases in humans and animals worldwide, and there is an increased interest in the role of animals in the mechanical transmission of these protozoa. To examine the role of yaks in this process, we examined the occurrence and genotypes of Cryptosporidium and G. duodenalis in yaks in western China. A total of 545 fecal specimens were collected from yaks from nine different counties in the central western region of China. The prevalence for Cryptosporidium spp. and G. duodenalis were 4.0 % (22/545) and 6.0 % (16/545), respectively. Mixed infections of Cryptosporidium and G. duodenalis were also detected in four specimens. The prevalence of both protozoa differed significantly between some age groups, with higher rates of infection in animals < 1 year old. Sequence analysis of the small subunit rRNA (SSU rRNA) gene of the Cryptosporidium isolates identified the species as C. parvum (n = 12), C. bovis (n = 6), C. ryanae (n = 3), and C. ubiquitum (n = 1). Genotyping based on 60-kDa glycoprotein (gp60) gene from five C. parvum isolates identified all as IId with three isolates identified as IIdA15G1, one as IIdA18G1, and one as IIdA19G1. One C. ubiquitum isolate was identified as subtype VIIa. Amongst the G. duodenalis isolates, 16 were identified as assemblage E at the SSU rRNA gene. Four novel glutamate dehydrogenase (gdh) subtypes and two triosephosphate isomerase (tpi) subtypes were found amongst the G. duodenalis assemblage E isolates. The presence of C. parvum subtype IIdA15G1, IIdA18G1, and IIdA19G1 isolates further confirms the dominance of the C. parvum IId subtypes in China. These findings also indicate that yaks may be a source of zoonotic Cryptosporidium infection, and this is the first report of G. duodenalis in yaks. The data presented here provides the basis for further genotyping or subtyping studies of G. duodenalis in yaks.

Cryptosporidium and Giardia duodenalis are gastro-intestinal parasites that infect human and animals worldwide. Both parasites share a broad host range and are believed to be zoonosis. The aim of this study was to identify the species of Cryptosporidium and assemblages of G. duodenalis in lambs and to elucidate their role in zoonotic transmission. A total of 389 fecal samples were collected from lambs and screened by microscopy and nested PCR targeting the small-subunit ribosomal RNA for Cryptosporidium; and the small-subunit ribosomal RNA, triose phosphate isomerase, β-giardin, and glutamate dehydrogenase genes for G. duodenalis. The prevalence of Cryptosporidium and G. duodenalis was 2.1% (8/389) and 2.6% (10/389), respectively. The infection rate at the three study sites ranged from 1.3 to 3.1% for Cryptosporidium and 1.6 to 3.9% for G. duodenalis; but variation was not statistically significant (p > 0.05). The finding also showed that there is no sex and age group associated difference in the occurrence of Cryptosporidium and G. duodenalis infections in lambs. Sequence analysis revealed that lambs were mono-infection with C. ubiquitum and G. duodenalis assemblage E. The analysis also indicated the presence of genetic variation within isolates of assemblage E; with 4 of them are novel genotypes at the small-subunit ribosomal RNA, β-giardin, and glutamate dehydrogenase genes. The findings of the current study showed that lambs are capable of harboring C. ubiquitum and G. duodenalis assemblage E. This finding suggests that lambs might be sources for potentially zoonotic Cryptosporidium species. This was first molecular study in lambs and contributes to a better understanding of the epidemiology of Cryptosporidium and G. duodenalis in central Ethiopia.