Reservoirs Of Human Pathogens Research Articles

Enduring pathogenicity of African strains of Salmonella on plastics and glass in simulated peri-urban environmental waste piles

In low- and middle-income countries, plastic has become a major constituent of landfills and urban dump sites. Environmental plastic pollution can also provide a novel surface for the formation of microbial biofilm, which often includes pathogenic bacteria and viruses. Here, under conditions simulating a peri-urban waste pile typical of an African informal settlement, we aimed to determine if pathogenic Salmonella spp. can retain their virulence following a prolonged period of desiccation on the surfaces of environmental plastic and glass. We show that clinically (and environmentally) relevant strains of Salmonella including S. Enteritidis, S. Typhimurium and S. Typhi can persist on plastic and glass for at least 28-days and that temperature (which increases with the depth of an urban waste pile) is a key determinant of this survival. All three strains of Salmonella retained their pathogenicity (determined by using a Galleria mellonella model of infection) following their recovery from the plastisphere indicating that plastics in the environment can act as reservoirs for human pathogens and could facilitate their persistence for extended periods of time. Pathogens colonising environmental plastic waste therefore pose a heightened public health risk, particularly in areas where people are frequently exposed to plastic pollution.

Clinically important E. coli strains can persist, and retain their pathogenicity, on environmental plastic and fabric waste

Plastic waste is ubiquitous in the environment and there are increasing reports of such waste being colonised by human pathogens. However, the ability of pathogens to persist on plastics for long periods, and the risk that they pose to human health, is unknown. Here, under simulated environmental conditions, we aimed to determine if pathogenic bacteria can retain their virulence following a prolonged period on plastic. Using antibiotic selection and luciferase expression for quantification, we show that clinically important strains of E. coli can survive on plastic for at least 28-days. Importantly, these pathogens also retained their virulence (determined by using a Galleria mellonella model as a surrogate for human infection) and in some cases, had enhanced virulence following their recovery from the plastisphere. This indicates that plastics in the environment can act as reservoirs for human pathogens and could facilitate their persistence for extended periods of time. Most importantly human pathogens in the plastisphere are capable of retaining their pathogenicity. Pathogens colonising environmental plastic waste therefore pose a heightened public health risk, particularly in areas where people are exposed to pollution.

Characterizing potential pathogens from intracellular bacterial community of protists in wastewater treatment plants

Protists are a trophically diverse and biogeochemically significant component of water environments and are widely reported as hosts of bacteria. However, the potential role of protists in wastewater treatment plants (WWTPs) as reservoirs for human pathogens does not appear to have received adequate attention. Here, a combination of fluorescence-activated cell sorting and Illumina sequencing was applied to characterize the dynamics of the internalized bacterial community of the enriched protists from the influents and effluents of five WWTPs. The results showed that Proteobacteria (mainly Betaproteobacteria) dominate the intracellular bacterial communities of protists in both influents and effluents of WWTPs, accounting for 72.6% of the total intracellular bacterial communities. The most frequently detected genus was Sulfuricurvum in the influent samples, Chryseobacterium and Pseudomonas were most prevalent in the effluent samples. Compared with the influents, a more diverse and abundant intracellular bacterial community was observed in the effluents. Moreover, the potential intracellular bacterial pathogens were 26 times higher in effluents than in influents, with Pseudomonas fluorescens and Pseudomonas putida significantly enriched in effluents. This work provides insights into the dynamics of bacterial communities and potential pathogens harbored by protists in the influents and effluents from WWTPs, contributing to the improved evaluation of biosafety in WWTPs.

Update on Novel Taxa and Revised Taxonomic Status of Bacteria Isolated from Nondomestic Animals Described in 2018 to 2021.

Revisions and new additions to bacterial taxonomy can have a significant widespread impact on clinical practice, infectious disease epidemiology, veterinary microbiology laboratory operations, and wildlife conservation efforts. The expansion of genome sequencing technologies has revolutionized our knowledge of the microbiota of humans, animals, and insects. Here, we address novel taxonomy and nomenclature revisions of veterinary significance that impact bacteria isolated from nondomestic wildlife, with emphasis being placed on bacteria that are associated with disease in their hosts or were isolated from host animal species that are culturally significant, are a target of conservation efforts, or serve as reservoirs for human pathogens.

Plant and Human Pathogenic Bacteria Exchanging their Primary Host Environments

Abstract Adaptation of plant and human pathogenic bacteria to niches of existence differing from their original ones is a sophisticated mechanism for survival. Research indicates that certain plant bacterial pathogens are capable of causing disease in humans, and some human bacterial pathogens can inhabit the plant environment and cause disease in plants. The infection of humans by plant bacteria may occur at direct physical contact with diseased plants and/or via the respiratory tract in mainly immunocompromised or otherwise stressed individuals. Indirect transmitters of plant and human microbes can be wind, rain, dust, insects, and animals. Human pathogenic bacteria may contaminate the soil and irrigation water, colonize the rhizosphere, more rarely also the phyllosphere, and can survive as epiphytes. Thus, the plant environment may become a reservoir of human pathogens. A source of foodborne human pathogenic bacteria can be unprocessed or unwashed fruits and vegetables. Especially during the last decade, the processes underlying the cross-kingdom performance of pathogenic bacteria are intensively researched. However, in reality, the risk for human health at infections by plant bacteria and by human bacterial pathogens surviving in the plant environment is still underestimated. The goal of the current review is to increase the interest in these issues in agricultural and general environments. Some basic strategies for infection and symptoms of diseases caused by the microorganisms under consideration are described. The potency of certain plant bacterial pathogens to surpass barriers towards humans and the interaction of human bacterial pathogens with the plant environment are addressed and the existing information is critically discussed.

Analysis of Eurasian Stone curlew (Burhinus oedicnemus) microbial flora reveals the presence of multi-drug resistant pathogens in agro-pastoral areas of Sicily (Italy)

Spread of multi-drug resistant (MDR) bacteria in natural environments pose a risk to human and animal health. Wild birds are considered to be reservoirs of human pathogens and vectors of antimicrobial resistance distribution in the environment. The aim of this study is to assess the occurrence of antibiotic resistant bacteria in isolates from bird specimens living in three agro-pastoral areas of the southeastern Sicily. We analyzed the microbiomes of the Eurasian Stone curlew Burhinus oedicnemus (Charadriiformes, Aves) and identified 91 Gram positive and 212 Gram negative strains, whose antimicrobial susceptibility to 11 and 9 antibiotic classes (respectively) was evaluated using agar disk diffusion test. Isolates showed significant levels of antimicrobial resistance, and a high percentage of MDR strains was found both between the Gram positive (49.4%) and the Gram negative (34.9%). Multi-drug resistance levels are higher among strains isolated in the beak and the eye than among enteric (faeces and cloaca) strains. Our results indicate high levels of MDR strains among wild bird populations, with a potential threat to wildlife and human populations.

Salmonella persistence in soil depends on reciprocal interactions with indigenous microorganisms.

Fresh fruits and vegetables have numerous benefits to human health. Unfortunately, their consumption is increasingly associated with food-borne diseases, Salmonella enterica being their most frequent cause in Europe. Agricultural soils were postulated as reservoir of human pathogens, contributing to the contamination of crops during the growing period. Since the competition with the indigenous soil microbiota for colonization sites plays a major role in the success of invading species, we hypothesized that reduced diversity will enhance the chance of Salmonella to successfully establish in agricultural environments. We demonstrated that the abundance of Salmonella drastically decreased in soil with highly diverse indigenous prokaryotic community, while in soil with reduced prokaryotic diversity, Salmonella persisted for a long period. Furthermore, in communities with low diversity, Salmonella had an impact on the abundance of other taxa. The high physiological plasticity allows Salmonella to use agricultural soils as alternative habitat which might provide a route of animal/human infections. In addition, adjusted transcriptional profile with amino acid biosynthesis and the glyoxylate cycle most prominently regulated, suggests an adaptation to the soil environment. Our results underline the importance of the maintenance of diverse soil microbiome as a part of strategy aiming at reduced risk of food-borne salmonellosis outbreaks.

Agricultural production systems can serve as reservoir for human pathogens.

Food-borne diseases are a threat to human health and can cause severe economic losses. Nowadays, in a growing and increasingly interconnected world, food-borne diseases need to be dealt with in a global manner. In order to tackle this issue, it is essential to consider all possible entry routes of human pathogens into the production chain. Besides the post-harvest handling of the fresh produce itself, also the prevention of contamination in livestock and agricultural soils are of particular importance. While the monitoring of human pathogens and intervening measures are relatively easy to apply in livestock and post-harvest, the investigation of the prevention strategies in crop fields is a challenging task. Furthermore, crop fields are interconnected with livestock via fertilizers and feed; therefore, a poor hygiene management can cause cross-contamination. In this review, we highlight the possible contamination of crop plants by bacterial human pathogens via the rhizosphere, their interaction with the plant and possible intervention strategies. Furthermore, we discuss critical issues and questions that are still open.

Programmed -2/-1 Ribosomal Frameshifting in Simarteriviruses: an Evolutionarily Conserved Mechanism.

The -2/-1 programmed ribosomal frameshifting (-2/-1 PRF) mechanism in porcine reproductive and respiratory syndrome virus (PRRSV) leads to the translation of two additional viral proteins, nonstructural protein 2TF (nsp2TF) and nsp2N. This -2/-1 PRF mechanism is transactivated by a viral protein, nsp1β, and cellular poly(rC) binding proteins (PCBPs). Critical elements for -2/-1 PRF, including a slippery sequence and a downstream C-rich motif, were also identified in 11 simarteriviruses. However, the slippery sequences (XXXUCUCU instead of XXXUUUUU) in seven simarteriviruses can only facilitate -2 PRF to generate nsp2TF. The nsp1β of simian hemorrhagic fever virus (SHFV) was identified as a key factor that transactivates both -2 and -1 PRF, and the universally conserved Tyr111 and Arg114 in nsp1β are essential for this activity. In vitro translation experiments demonstrated the involvement of PCBPs in simarterivirus -2/-1 PRF. Using SHFV reverse genetics, we confirmed critical roles of nsp1β, slippery sequence, and C-rich motif in -2/-1 PRF in SHFV-infected cells. Attenuated virus growth ability was observed in SHFV mutants with impaired expression of nsp2TF and nsp2N. Comparative genomic sequence analysis showed that key elements of -2/-1 PRF are highly conserved in all known arteriviruses except equine arteritis virus (EAV) and wobbly possum disease virus (WPDV). Furthermore, -2/-1 PRF with SHFV PRF signal RNA can be stimulated by heterotypic nsp1βs of all non-EAV arteriviruses tested. Taken together, these data suggest that -2/-1 PRF is an evolutionarily conserved mechanism employed in non-EAV/-WPDV arteriviruses for the expression of additional viral proteins that are important for viral replication.IMPORTANCE Simarteriviruses are a group of arteriviruses infecting nonhuman primates, and a number of new species have been established in recent years. Although these arteriviruses are widely distributed among African nonhuman primates of different species, and some of them cause lethal hemorrhagic fever disease, this group of viruses has been undercharacterized. Since wild nonhuman primates are historically important sources or reservoirs of human pathogens, there is concern that simarteriviruses may be preemergent zoonotic pathogens. Thus, molecular characterization of simarteriviruses is becoming a priority in arterivirology. In this study, we demonstrated that an evolutionarily conserved ribosomal frameshifting mechanism is used by simarteriviruses and other distantly related arteriviruses for the expression of additional viral proteins. This mechanism is unprecedented in eukaryotic systems. Given the crucial role of ribosome function in all living systems, the potential impact of the in-depth characterization of this novel mechanism reaches beyond the field of virology.

1150. Cleaning High Touch Surfaces of Patients’ Rooms: Make It Easier, and It Simply Gets Cleaner

BackgroundThe healthcare environment has been established as a reservoir for human pathogens and specifically multidrug-resistant organisms (MDRO). High touch surfaces and fomites in a patient’s room mediate transmission between infected and uninfected patients and personnel. Efforts to reduce hospital-associated infections due to MDROs often focus on room cleaning; however, adherence to and thoroughness of cleaning pose significant challenges.MethodsA crossover trial was implemented in January 2016 (for 15 months) at Assaf Harofeh Medical Center (Israel) in four identical medical units. Single-use wipes (Clinell®; universal wipes and sporicidal wipes for rooms of patients with C. difficile), were compared with common practices which consisted of reusable cloths and bleach (1,000–5,000 ppm). Six-month cleaning and intervention periods were used on units in alternating sequences, separated by washout periods. Cleaning was monitored twice a week (bedrail, bedside table, clinical binder, call button, and lamp switch), by a fluorescent marker system (Clinell®). Comparisons used GEE with clustering for room. Staff were surveyed on intervention feasibility, acceptability, and satisfaction.ResultsComplete cleaning in all five test locations was found in 23% of 400 total assessments and was more common in the intervention group (34% vs. 12%; OR = 3.7; P < 0.001). Cleaning adherence was highest for the bed rail (71%) and lowest for the call button (38%). The use of wipes had the largest effect on adherence for the light switch (59% vs. 26%; OR = 4.2; P < 0.001). Intervention timing was not associated with overall adherence (P = 0.10). 94% of staff reported overall satisfaction of “very good” or “excellent,” and 90% of staff reported that use of the wipes shortened the cleaning process.ConclusionThe use of cleaning wipes resulted in greater adherence to room cleaning and the method was reported to be acceptable to staff. Future aims of this large study (over 10,000 patients were enrolled and data collection not yet completed) are to determine the impact of this intervention on rates of hospital-acquired infections, MDRO acquisitions, and mortality.Disclosures E. T. Martin, Clinell: Grant Investigator, Research grant. D. Marchaim, Clinell: Grant Investigator, Grant recipient.

The Transferable Resistome of Produce.

Produce is increasingly recognized as a reservoir of human pathogens and transferable antibiotic resistance genes. This study aimed to explore methods to characterize the transferable resistome of bacteria associated with produce. Mixed salad, arugula, and cilantro purchased from supermarkets in Germany were analyzed by means of cultivation- and DNA-based methods. Before and after a nonselective enrichment step, tetracycline (TET)-resistant Escherichia coli were isolated and plasmids conferring TET resistance were captured by exogenous plasmid isolation. TET-resistant E. coli isolates, transconjugants, and total community DNA (TC-DNA) from the microbial fraction detached from leaves or after enrichment were analyzed for the presence of resistance genes, class 1 integrons, and various plasmids by real-time PCR and PCR-Southern blot hybridization. Real-time PCR primers were developed for IncI and IncF plasmids. TET-resistant E. coli isolated from arugula and cilantro carried IncF, IncI1, IncN, IncHI1, IncU, and IncX1 plasmids. Three isolates from cilantro were positive for IncN plasmids and blaCTX-M-1 From mixed salad and cilantro, IncF, IncI1, and IncP-1β plasmids were captured exogenously. Importantly, whereas direct detection of IncI and IncF plasmids in TC-DNA failed, these plasmids became detectable in DNA extracted from enrichment cultures. This confirms that cultivation-independent DNA-based methods are not always sufficiently sensitive to detect the transferable resistome in the rare microbiome. In summary, this study showed that an impressive diversity of self-transmissible multiple resistance plasmids was detected in bacteria associated with produce that is consumed raw, and exogenous capturing into E. coli suggests that they could transfer to gut bacteria as well.IMPORTANCE Produce is one of the most popular food commodities. Unfortunately, leafy greens can be a reservoir of transferable antibiotic resistance genes. We found that IncF and IncI plasmids were the most prevalent plasmid types in E. coli isolates from produce. This study highlights the importance of the rare microbiome associated with produce as a source of antibiotic resistance genes that might escape cultivation-independent detection, yet may be transferred to human pathogens or commensals.

An Evaluation of Removal Trapping to Control Rodents Inside Homes in a Plague-Endemic Region of Rural Northwestern Uganda.

Rodents pose a significant threat to human health, particularly in rural subsistence farming communities in Africa, where rodents threaten food security and serve as reservoirs of human pathogens, including the agents of plague, leptospirosis, murine typhus, rat-bite fever, Lassa fever, salmonellosis, and campylobacteriosis. Our study focused on the plague-endemic West Nile region of Uganda, where a majority of residents live in Uganda government-defined poverty, rely on subsistence farming for a living, and frequently experience incursions of rodents into their homes. In this study, we show that rodent removal was achieved in a median of 6 days of intensive lethal trapping with multiple trap types (range: 0-16 days). However, rodent abundance in 68.9% of homesteads returned to pretreatment levels within a median of 8 weeks (range 1-24 weeks), and at least a single rodent was captured in all homesteads by a median of 2 weeks (range 1-16 weeks) after removal efforts were terminated. Results were similar between homesteads that practiced rodent control whether or not their neighbors implemented similar strategies. Overall, intensive lethal trapping inside homes appears to be effective at reducing rodent abundance, but control was short lived after trapping ceased.

Detection of alpha- and betacoronaviruses in rodents from Yunnan, China

BackgroundRodents represent the most diverse mammals on the planet and are important reservoirs of human pathogens. Coronaviruses infect various animals, but to date, relatively few coronaviruses have been identified in rodents worldwide. The evolution and ecology of coronaviruses in rodent have not been fully investigated.ResultsIn this study, we collected 177 intestinal samples from thress species of rodents in Jianchuan County, Yunnan Province, China. Alphacoronavirus and betacoronavirus were detected in 23 rodent samples from three species, namely Apodemus chevrieri (21/98), Eothenomys fidelis (1/62), and Apodemus ilex (1/17). We further characterized the full-length genome of an alphacoronavirus from the A. chevrieri rat and named it as AcCoV-JC34. The AcCoV-JC34 genome was 27,649 nucleotides long and showed a structure similar to the HKU2 bat coronavirus. Comparing the normal transcription regulatory sequence (TRS), 3 variant TRS sequences upstream the spike (S), ORF3, and ORF8 genes were found in the genome of AcCoV-JC34. In the conserved replicase domains, AcCoV-JC34 was most closely related to Rattus norvegicus coronavirus LNRV but diverged from other alphacoronaviruses, indicating that AcCoV-JC34 and LNRV may represent a novel alphacoronavirus species. However, the S and nucleocapsid proteins showed low similarity to those of LRNV, with 66.5 and 77.4% identities, respectively. Phylogenetic analysis revealed that the S genes of AcCoV-JC34, LRNV, and HKU2 formed a distinct lineage with all known coronaviruses.ConclusionsBoth alphacoronaviruses and betacoronaviruses were detected in Apodemus chevrieri in the Yunnan Province of China, indicating that Apodemus chevrieri is an important host for coronavirus. Several new features were identified in the genome of an Apodemus chevrieri coronavirus. The phylogenetic distance to other coronaviruses suggests a variable origin and evolutionary route of the S genes of AcCoV-JC34, LRNV, and HKU2. These results indicate that the diversity of rodent coronaviruses is much higher than previously expected. Further surveillance and functional studies of these coronaviruses will help to better understand the importance of rodent as host for coronaviruses.

The Micro-Bio-Trojans: Free-living amoebae as reservoirs for human pathogens, giant viruses, and other surprises

"The Micro-Bio-Trojans: Free-living amoebae as reservoirs for human pathogens, giant viruses, and other surprises." Ultrastructural Pathology, 41(1), pp. 81–82

Whole-Genome Sequencing Reveals Genetic Variation in the Asian House Rat.

Whole-genome sequencing of wild-derived rat species can provide novel genomic resources, which may help decipher the genetics underlying complex phenotypes. As a notorious pest, reservoir of human pathogens, and colonizer, the Asian house rat, Rattus tanezumi, is successfully adapted to its habitat. However, little is known regarding genetic variation in this species. In this study, we identified over 41,000,000 single-nucleotide polymorphisms, plus insertions and deletions, through whole-genome sequencing and bioinformatics analyses. Moreover, we identified over 12,000 structural variants, including 143 chromosomal inversions. Further functional analyses revealed several fixed nonsense mutations associated with infection and immunity-related adaptations, and a number of fixed missense mutations that may be related to anticoagulant resistance. A genome-wide scan for loci under selection identified various genes related to neural activity. Our whole-genome sequencing data provide a genomic resource for future genetic studies of the Asian house rat species and have the potential to facilitate understanding of the molecular adaptations of rats to their ecological niches.

Rodents as reservoirs of human pathogens in Bulgaria

Small mammals are reservoirs of various human pathogens. The aim of this work was to investigate infections with human pathogens in rodents trapped in different regions of Bulgaria. A total of 284 rodents were investigated by PCR for detection of the flagellin gene of borreliae within Borrelia burgdorferi sensu lato complex, ankA gene of Anaplasma phagocytophilum and nucleoprotein gene of hantavirus Dobrava - conventional nested RT-PCR and Real Time PCR with TaqMan probe. B. burgdorferi was detected in 64/284 (22.5%) of the investigated rodents by PCR. Of them, 41 samples originated from Apodemus flavicollis, 20 from A. agrarius, and 3 from A. sylvaticus. Overall, 33 of the investigated 284 rodents were infected with Anaplasma phagocytophilum (11.6%) - 11 Apodemus flavicollis (infectivity rate 8.6% of the 128 investigated), 13 Apodemus agrarius (infectivity rate 13.5% of the 96 tested), and 1 Apodemus sylvaticus (infectivity rate 9% of the 11 tested). Hantavirus RNA was detected in 9 of the rodents. Only Dobrava-Belgrade virus but not Puumala or Saaremaa virus was detected. Almost all infected rodents were A. flavicollis (8/9 PCR-positive rodents). Rodents are important reservoirs of human pathogens. In this study, active infection in rodents was confirmed by detection of microorganism's genome. Remarkably, a high number of rodents from genus Apodemus were infected with borreliae. The high rate of detection of A. phagocytophilum in rodents from A. agrarius species suggested that this species might serve as major reservoir of human anaplasmosis in Bulgaria. Mainly infected with hantaviruses were A. flavicollis mice, known as reservoir of Dobrava hantavirus but hantavirus infections were detected also in A. agrarius mice. Medical authorities should be aware of the risk for humans.

Evidence that rodent control strategies ought to be improved to enhance food security and reduce the risk of rodent-borne illnesses within subsistence farming villages in the plague-endemic West Nile region, Uganda

Rodents pose serious threats to human health and economics, particularly in developing countries where the animals play a dual role as pests: they are reservoirs of human pathogens, and they inflict damage levels to stored products sufficient to cause food shortages. To assess the magnitude of the damage caused by rodents to crops, their level of contact with humans, and to better understand current food storage and rodent control practices, we conducted a survey of 37 households from 17 subsistence farming villages within the West Nile region of Uganda. Our survey revealed that rodents cause both pre- and post-harvest damage to crops. Evidence of rodent access to stored foods was reported in conjunction with each of the reported storage practices. Approximately half of the respondents reported that at least one family member had been bitten by a rat within the previous three months. Approximately two-thirds of respondents practiced some form of rodent control in their homes. The abundance of rodents was similar within homes that practiced or did not practice rodent control. Together, our results show that current efforts are inadequate for effectively reducing rodent abundance in homes.

Reservoirs of human pathogens: amoeba-associated microorganisms in the environment

Microorganisms, that evolve to acquire resistance to environmental amoeba, are likely to become human pathogens due to the physiological similarities of free-living amoebae to human macrophages. In this sense free-living amoebae can be regarded as nurseries of pathogenic microorganisms. Due to the widespread distribution of amoebae in the environment and their resistance to current disinfection procedures, they may constitute important reservoirs of pathogenic microorganisms. Striking examples are Legionella pneumophila and several mycobacteria including Mycobacterium tuberculosis. This work represents the first attempt to detect and characterize amoebae and their associated microorganisms in Portugal.Detection, isolation and in vitro culture of amoebae from several environmental sources, including lagoon and estuarine water and sediments, were performed according to previously developed methods. Identification of the isolated amoebae was done by optical microscopy based on morphological criteria and by DNA sequence analysis of PCR products amplified with one of the following two sets of primers: EUK and ITS. Transmission electron microscopy (TEM) studies and PCR/sequencing approaches were used to detect and identify amoeba-associated microorganisms (AAMs). Bacterial 16S region was amplified with the primers 616V/630R. TEM studies were performed according to standard procedures. In short, samples were fixed sequentially in glutaraldehyde, osmium tetroxide and uranyl acetate, dehydrated in ethanol and embedded in Epon-Araldite. Thin sections contrasted with uranyl acetate and lead citrate were observed with a JEOL 100-SX electron microscope.Several species of amoeba (Acanthamoeba lenticulata, A. polyphaga, A. rhyzodes, Platyamoeba oblongata, Saccamoeba limax, Vannella simplex, Vannella sp. and other unidentified amoebae) were found and AAMs were detected both by TEM and PCR/sequencing. The bacteria species Variovorax paradoxus, previously found in association with Saccamoeba and Arcella, were isolated and identified by the PCR/sequencing approach, which also allowed the detection of an unidentified species with about 85% identity with Marivirga tractuosa, a species not yet associated with amoebae. These results point to the existence of AAMs in the environments subjected to this study and the need to evaluate their pathogenic potential. This is an important issue particularly in environments related to human recreational, nutritional and public health activities.

Wild primate populations in emerging infectious disease research: the missing link?

Wild primate populations, an unexplored source of information regarding emerging infectious disease, may hold valuable clues to the origins and evolution of some important pathogens. Primates can act as reservoirs for human pathogens. As members of biologically diverse habitats, they serve as sentinels for surveillance of emerging pathogens and provide models for basic research on natural transmission dynamics. Since emerging infectious diseases also pose serious threats to endangered and threatened primate species, studies of these diseases in primate populations can benefit conservation efforts and may provide the missing link between laboratory studies and the well-recognized needs of early disease detection, identification, and surveillance.

Prevalence and some properties of verotoxin (Shiga-like toxin)-producing Escherichia coli in seven different species of healthy domestic animals.

Fecal samples from 720 healthy, domestic animals representing seven different species (cattle, sheep, goats, pigs, chickens, dogs, and cats) were investigated for verotoxin (VT [Shiga-like toxin])-producing Escherichia coli (VTEC). VTEC were isolated from 208 animals (28.9%), most frequently from sheep (66.6% VTEC carriers), goats (56.1%), and cattle (21.1%). VTEC were isolated less frequently from pigs (7.5%), cats (13.8%), and dogs (4.8%) and were not found in chickens (< 0.7%). Forty-one different O:H serotypes and 23 untypeable O-groups were isolated. Five serotypes (O5:H-, O91:H-, O146:H21, O87:H16, and O82:H8) occurred in more than one animal species. Serotypes O5:H-, O91:H-, O146:H21, O128:H2, and OX3:H8 represented 54.8% of the VTEC strains. Nearly 60% of all VTEC O:H serotypes isolated in this study have been implicated as human pathogens, indicating that healthy, domestic animals may serve as a reservoir of human pathogens. All VTEC, except nine feline strains, hybridized with one or both of the VT1 and VT2 specific DNA probes. VT production and enterohemolysin (E-Hly+) production were associated in E. coli from goats, sheep, and cattle but not in E. coli from chickens, pigs, dogs, and cats. A close association of VT with E-Hly+ was found in O5:H-, O146:H21, O128:H2, O77:H4, O119:H25, and O123:(H10) strains. Thirty of 240 (12.5%) E-Hly+ strains hybridized with an E-Hly+ specific DNA probe, indicating heterogeneity of regulatory or structural E-Hly+ genes in strains of E. coli.