Comparative Analysis of Codon Usage Bias Patterns in Microsporidian Genomes

The sub-3 Mbp genomes from microsporidian species of the Encephalitozoon genus are the smallest known among eukaryotes and paragons of genomic reduction and compaction in parasites. However, their diminutive stature is not characteristic of all Microsporidia, whose genome sizes vary by an order of magnitude. This large variability suggests that different evolutionary forces are applied on the group as a whole. In this study, we have compared the codon usage bias (CUB) between eight taxonomically distinct microsporidian genomes: Encephalitozoon intestinalis, Encephalitozoon cuniculi, Spraguea lophii, Trachipleistophora hominis, Enterocytozoon bieneusi, Nematocida parisii, Nosema bombycis and Nosema ceranae. While the CUB was found to be weak in all eight Microsporidia, nearly all (98%) of the optimal codons in S. lophii, T. hominis, E. bieneusi, N. parisii, N. bombycis and N. ceranae are fond of A/U in third position whereas most (64.6%) optimal codons in the Encephalitozoon species E. intestinalis and E. cuniculi are biased towards G/C. Although nucleotide composition biases are likely the main factor driving the CUB in Microsporidia according to correlation analyses, directed mutational pressure also likely affects the CUB as suggested by ENc-plots, correspondence and neutrality analyses. Overall, the Encephalitozoon genomes were found to be markedly different from the other microsporidians and, despite being the first sequenced representatives of this lineage, are uncharacteristic of the group as a whole. The disparities observed cannot be attributed solely to differences in host specificity and we hypothesize that other forces are at play in the lineage leading to Encephalitozoon species.     

Intestinal Parasites among Wild Rodents in Northern Gangwon-do,Korea

To determine geographical patterns of natural parasite infections among wild rodents, a total of 46 wild rodents from 3 different localities in northern Gangwon-do (Province), Korea were examined for intestinal parasite infections. Along with nematodes such as hookworms and Syphacia spp., Plagiorchis muris (2 specimens) (Trematoda) were collected from striped field mice, Apodemus agrarius. In a Korean wood mouse, Apodemus peninsulae, the overall nematode infections were similar to A. agrarius, but an adult worm of Echinostoma hortense (Trematoda) was collected. In addition, 2 species of cestodes, i.e., Hymenolepis nana and Hymenolepis diminuta, were collected from A. agrarius. Through this survey, A. agrarius and A. peninsule were confirmed as the natural definite hosts for zoonotic intestinal helminths, i.e., P. muris, E. hortense, H. nana, and H. diminuta, in northern Gangwon-do, Korea. Considering increased leisure activities around these areas, seasonal and further comprehensive surveys on wild rodents seem to be needed to prevent zoonotic parasite infections.     

Detection and Molecular Characterization of Cryptosporidium spp. from Wild Rodents and Insectivores in South Korea

In order to examine the prevalence of Cryptosporidium infection in wild rodents and insectivores of South Korea and to assess their potential role as a source of human cryptosporidiosis, a total of 199 wild rodents and insectivore specimens were collected from 10 regions of South Korea and screened for Cryptosporidium infection over a period of 2 years (2012-2013). A nested-PCR amplification of Cryptosporidium oocyst wall protein (COWP) gene fragment revealed an overall prevalence of 34.2% (68/199). The sequence analysis of 18S rRNA gene locus of Cryptosporidium was performed from the fecal and cecum samples that tested positive by COWP amplification PCR. As a result, we identified 4 species/genotypes; chipmunk genotype I, cervine genotype I, C. muris, and a new genotype which is closely related to the bear genotype. The new genotype isolated from 12 Apodemus agrarius and 2 Apodemus chejuensis was not previously identified as known species or genotype, and therefore, it is supposed to be a novel genotype. In addition, the host spectrum of Cryptosporidium was extended to A. agrarius and Crosidura lasiura, which had not been reported before. In this study, we found that the Korean wild rodents and insectivores were infected with various Cryptosporidium spp. with large intra-genotypic variationa, indicating that they may function as potential reservoirs transmitting zoonotic Cryptosporidium to livestock and humans.     

Comparison of UV Inactivation of Spores of Three Encephalitozoon Species with That of Spores of Two DNA Repair-Deficient Bacillus subtilis Biodosimetry Strains

When exposed to 254-nm UV, spores of Encephalitozoon intestinalis, Encephalitozoon cuniculi, and Encephalitozoon hellem exhibited 3.2-log reductions in viability at UV fluences of 60, 140, and 190 J/m², respectively, and demonstrated UV inactivation kinetics similar to those observed for endospores of DNA repair-defective mutant Bacillus subtilis strains used as biodosimetry surrogates. The results indicate that spores of Encephalitozoon spp. are readily inactivated at low UV fluences and that spores of UV-sensitive B. subtilis strains can be useful surrogates in evaluating UV reactor performance.     

The Distribution and Diversity of Bartonella Species in Rodents and Their Ectoparasites across Thailand

Our study highlights the surveillance of Bartonella species among rodents and their associated ectoparasites (ticks, fleas, lice, and mites) in several regions across Thailand. A total of 619 rodents and 554 pooled ectoparasites (287 mite pools, 62 flea pools, 35 louse pools, and 170 tick pools) were collected from 8 provinces within 4 regions of Thailand. Bandicota indica (279), Rattus rattus (163), and R. exulans (96) were the most prevalent species of rats collected in this study. Real-time PCR assay targeting Bartonella-specific ssrA gene was used for screening and each positive sample was confirmed by PCR using nuoG gene. The prevalence of Bartonella DNA in rodent (around 17%) was recorded in all regions. The highest prevalence of Bartonella species was found in B. savilei and R. rattus with the rate of 35.7% (5/14) and 32.5% (53/163), respectively. High prevalence of Bartonella-positive rodent was also found in B. indica (15.1%, 42/279), and R. norvegicus (12.5%, 5/40). In contrast, the prevalence of Bartonella species in ectoparasites collected from the rats varied significantly according to types of ectoparasites. A high prevalence of Bartonella DNA was found in louse pools (Polyplax spp. and Hoplopleura spp., 57.1%) and flea pools (Xenopsylla cheopis, 25.8%), while a low prevalence was found in pools of mites (Leptotrombidium spp. and Ascoschoengastia spp., 1.7%) and ticks (Haemaphysalis spp., 3.5%). Prevalence of Bartonella DNA in ectoparasites collected from Bartonella-positive rodents (19.4%) was significantly higher comparing to ectoparasites from Bartonella-negative rodents (8.7%). The phylogenetic analysis of 41 gltA sequences of 16 Bartonella isolates from rodent blood and 25 Bartonella-positive ectoparasites revealed a wide range of diversity among Bartonella species with a majority of sequences (61.0%) belonging to Bartonella elizabethae complex (11 rodents, 1 mite pool, and 5 louse pools), while the remaining sequences were identical to B. phoceensis (17.1%, 1 mite pool, 5 louse pools, and 1 tick pool), B. coopersplainensis (19.5%, 5 rodents, 1 louse pool, and 2 tick pools), and one previously unidentified Bartonella species (2.4%, 1 louse pool).     

Molecular Identification of Echinococcus multilocularis Infection in Small Mammals from Northeast,Iran

Background

Alveolar echinococcosis is a zoonotic disease caused by the metacestode of Echinococcus multilocularis. Many species of small mammals, including arvicolid rodents or Ochotona spp., are natural intermediate hosts of the cestode. The main aim of this study was to identify natural intermediate hosts of E. multilocularis in Chenaran County, Razavi Khorasan Province, northeastern Iran, where the prevalence of infected wild and domestic carnivores is high.

Methodology/Principal Findings

A program of trapping was carried out in five villages in which this cestode was reported in carnivores. The livers of 85 small mammals were investigated for the presence of E. multilocularis infection using multiplex PCR of mitochondrial genes. Infections were identified in 30 specimens: 23 Microtus transcaspicus, three Ochotona rufescens, two Mus musculus, one Crocidura gmelini, and one Apodemus witherbyi.

Conclusions/Significance

A range of small mammals therefore act as natural intermediate hosts for the transmission of E. multilocularis in Chenaran County, and the prevalence suggested that E. multilocularis infection is endemic in this region. The existence of the life cycle of this potentially lethal cestode in the vicinity of human habitats provides a significant risk of human infection.     

Seroprevalence of Encephalitozoon cuniculi in Pet Rabbits in Korea

Encephalitozoon cuniculi is a microsporidian parasite commonly found in rabbits that can infect humans, causing encephalitozoonosis. The prevalence of encephalitozoonosis is not well documented, even when many clinics suspect pet rabbits as being highly infected. This study investigated the seropositivity of E. cuniculi using ELISA. The examination of 186 rabbits using ELISA showed that 22.6% (42/186) were seropositive against E. cuniculi. In analysis with healthy status, all 42 seropositive sera were collected from clinically normal rabbits. Moreover, the gender and age of pet rabbits did not have anysignificant effect on E. cuniculi infection. To the best of our knowledge, this is the first report to describe the seroprevalence of E. cuniculi in pet rabbits and suggests that pet rabbits could act as an important reservoir of encephalitozoonosis for both pet animals and humans in Korea.     

Establishing a New Species Encephalitozoon pogonae for the Microsporidian Parasite of Inland Bearded Dragon Pogona vitticeps Ahl 1927 (Reptilia,Squamata, Agamidae)

The microsporidium parasitizing Inland Bearded Dragons Pogona vitticeps, and developing primarily in macrophages within foci of granulomatous inflammation of different organs, is described as a new species Encephalitozoon pogonae. Establishing the new species was based on sequencing the ITS‐SSUrDNA region of the ribosomal gene and consequent SSUrDNA‐inferred phylogenetic analyses, as well as on comparison of pathogenesis, host specificity, and ultrastructure among Encephalitozoon species and isolates. The new species is closely related to E. lacertae and E. cuniculi. Analysis of the literature suggests that this microsporidium has been reported previously as an unidentified microsporidian species or isolate of E. cuniculi and may represent a common infection in bearded dragons. All stages of E. pogonae develop in parasitophorous vacuoles. Uninucleate spores on methanol‐fixed smears measured 2.1 × 1.1 μm, range 1.7–2.6 × 0.9–1.7 μm; on ultrathin sections spores measured 0.8–1.1 × 1.8–2.2 μm. Ultrastructural study revealed 3–6 polar filament coils, a mushroom‐shaped polar disk, and a polar sac embracing half of the volume occupied by the lamellar polaroplast. In activated spores, polar filament everted eccentrically. The overall morphology and intracellular development of E. pogonae were similar to other Encepahalitozoon spp. We also review the existing data on microsporidia infecting reptiles.     

Intestinal Nematodes from Small Mammals Captured near the Demilitarized Zone,Gyeonggi Province,Republic of Korea

A total of 1,708 small mammals (1,617 rodents and 91 soricomorphs), including Apodemus agrarius (n = 1,400), Microtus fortis (167), Crocidura lasiura (91), Mus musculus (32), Myodes (= Eothenomys) regulus (9), Micromys minutus (6), and Tscherskia (= Cricetulus) triton (3), were live-trapped at US/Republic of Korea (ROK) military training sites near the demilitarized zone (DMZ) of Paju, Pocheon, and Yeoncheon, Gyeonggi Province from December 2004 to December 2009. Small mammals were examined for their intestinal nematodes by necropsy. A total of 1,617 rodents (100%) and 91 (100%) soricomorphs were infected with at least 1 nematode species, including Nippostrongylus brasiliensis, Heligmosomoides polygyrus, Syphacia obvelata, Heterakis spumosa, Protospirura muris, Capillaria spp., Trichuris muris, Rictularia affinis, and an unidentified species. N. brasiliensis was the most common species infecting small mammals (1,060; 62.1%) followed by H. polygyrus (617; 36.1%), S. obvelata (370; 21.7%), H. spumosa (314; 18.4%), P. muris (123; 7.2%), and Capillaria spp. (59; 3.5%). Low infection rates (0.1-0.8%) were observed for T. muris, R. affinis, and an unidentified species. The number of recovered worms was highest for N. brasiliensis (21,623 worms; mean 20.4 worms/infected specimen) followed by S. obvelata (9,235; 25.0 worms), H. polygyrus (4,122; 6.7 worms), and H. spumosa (1,160; 3.7 worms). A. agrarius demonstrated the highest prevalence for N. brasiliensis (70.9%), followed by M. minutus (50.0%), T. triton (33.3%), M. fortis (28.1%), M. musculus (15.6%), C. lasiura (13.2%), and M. regulus (0%). This is the first report of nematode infections in small mammals captured near the DMZ in ROK.     

Chlorine Inactivation of Spores of Encephalitozoon spp.

This report is an extension of a preliminary investigation on the use of chlorine to inactivate spores of Encephalitozoon intestinalis and to investigate the effect of chlorine on two other species, E cuniculi and E. hellem, associated with human infection. The 50% tissue culture infective doses of these three species were also determined. On the basis of the results obtained, it appears that chlorination of water is an effective means of controlling spores of these organisms in the aquatic environment.     

Echinostome Infections in the Striped-Field Mouse, Apodemus agrarius, and the Ussuri White-Toothed Shrew, Crocidura lasiura, Caught Near the Demilitarized Zone, Gyeonggi-do (Province), Republic of Korea

A total of 1,498 small mammals (rodents and insectivores), including Apodemus agrarius (n = 1,366), Crocidura lasiura (54), Mus musculus (32), Micronytus fortis (28), Eothenomys regulus (9), Micronys minutes (6), and Cricetulus triton (3), were live-trapped in Gyeonggi-do (Province) (Paju-si, Pocheon-gun, and Yeoncheon-gun) near the demilitarized zone (DMZ) from December 2004 to September 2005. A. agrarius was found to be infected with 3 species of echinostomes (Echinostoma hortense, Echinostoma cinetorchis, and Euparyphium murinum), while C. lasiura was infected with 1 species (Echinochasmus japonicas) of echinostome. Other mammals were free from echinostome infections. Total 16 E. hortense were detected in 7 (0.5%) mice, 9 E. cinetorchis from 5 (0.4%), and 3 E. murinum from 2 (0.1%) out of 1.366 A. agrarius examined. E. japonicus was found only in 1 (1.9%; total 3 specimens) C. lasiura. These results demonstrate that A. agrarius and C. lasiura, inhabiting near the DMZ of Gyeonggi-do serve as the natural definitive hosts for several species of echinostomes, although their infection rates are low. This is the first record of natural infections of A. agrarius with E. cinetorchis and C. lasiura with E. japonicus in the Republic of Korea.     

Echinostoma revolutum: Freshwater Snails as the Second Intermediate Hosts in Chiang Mai,Thailand

The occurrence of 37-collar spined echinostome metacercariae in freshwater snails was investigated in 6 districts of Chiang Mai Province, Thailand, from October 2011 to April 2012. A total of 2,914 snails that belong to 12 species were examined, and 7 snail species (Clea helena, Eyriesia eyriesi, Bithynia funiculata, Bithynia siamensis siamensis, Filopaludina doliaris, Filopaludina sumatrensis polygramma, and Filopaludina martensi martensi) were found infected with echinostome metacercariae. The prevalence of metacercariae was the highest in Filopaludina spp. (38.5-58.7%) followed by B. funiculata (44.0%), E. eyriesi (12.5%), B. siamensis siamensis (8.2%), and C. helena (5.1%). Metacercariae were experimentally fed to hamsters and domestic chicks, and adult flukes were recovered from both hosts at days 15 and 20 post-infection. The adult flukes were identified based on morphological features, morphometrics, host-parasite relationships, and geographical distribution. They were compatible to Echinostoma revolutum or Echinostoma jurini, with only minor differences. As the adults were recovered from both hamsters and chicks, our specimens were more compatible to E. revolutum rather than E. jurini (reported only from mammals). This is the first report for metacercariae of E. revolutum in the snail host, C. helena, and also confirmed that Filopaludina spp., E. eryresi, and Bithynia spp. act as the second intermediate hosts of E. revolutum under natural conditions, which are indigenously distributed in Chiang Mai province.     

Identification of Encephalitozoon cuniculi genotype III and two novel genotypes of Enterocytozoon bieneusi in swine

Samples of intestinal content from thirty fattened pigs of six farms slaughtered at an abattoir in North-Western Germany, and faecal samples of four pigs kept as laboratory animals at the Federal Institute for Risk Assessment (BfR, Berlin, Germany) were investigated for the occurrence of microsporidia by light microscopy, PCR and sequencing. A modified Webers trichrome staining and the immunohistochemistry (the Avidin-Biotin-Peroxidase-Complex technique with a polyclonal anti-Encephalitozoon cuniculi-serum and monoclonal antibodies against Encephalitozoon intestinalis and Enterocytozoon bieneusi) was used as a screening method for the light microscopical detection of these pathogenic eukaryotes. By this light microscopically methods microsporidia suspected organisms were found in all samples (100%). By the use of PCR, microsporidia were identified in fourteen samples (41.2%). The prevalence of microsporidia infections among the farms diversifies from 0 to 80% as considered by PCR. E. bieneusi was the most prevalent species and was identified in twelve fattened pigs (40%) from five of the six tested farms (83.3%) and in two of the four laboratory animals (50%). Three of the E. bieneusi species belonged to the genotype O, one to the genotype E, and one to the genotype F. Two isolates were identified as novel genotypes and two samples showed a mixed infection of different genotypes. In three faecal samples of the pigs from two farms E. cuniculi genotype III was identified. One sample contained both microsporidia species. To our knowledge, this is the first time that the genotype III of E. cuniculi was identified in swine.     

Intestinal Helminthic Infections in Striped Field Mice,Apodemus agrarius,from Two Southern Regions of Korea

The present study was performed to know the infection status of intestinal helminths in a most common species of field mice, Apodemus agrarius, from 2 southern regions of Korea. Total 133 and 103 mice were collected by the mouse trap in Hapcheon-gun, Gyeongsangnam-do and Gurye-gun, Jeollanam-do, respectively, from July 2005 to June 2006. The small intestine of each mouse was resected and longitudinally opened with a pair of scissors. The intestinal contents were washed with 0.85% saline until the supernatant became clear. Helminths were collected with naked eyes or under a stereomicroscope from the sediment of the intestinal content. More than 11 species of helminths (4 nematode spp., 5 trematode spp., and 2 cestode spp.) were recovered. Among these, heligmosomoid nematodes (97.5%) was the most highly and heavily infected species. As the members of trematodes, Plagiorchis muris, Brachylaima sp., Echinostoma hortense, Echinostoma cinetorchis, and unidentified echinostome larvae were found in the small intestines of 35 (14.8%), 12 (5.1%), 6 (2.5%), 1 (0.4%), and 1 (0.4%) mice respectively. Two species of tapeworms, Hymenolepis nana and Hymenolepis diminuta were also detected in 79 (33.5%) and 21 (8.9%) mice, respectively. Conclusively, heligmosomoid nematodes were the most prevalent (dominant) species among more than 11 helminth species detected, and Brachylaima sp. fluke is newly added in the list of intestinal trematodes in Korea.     

Molecular Surveillance of Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi by Genotyping and Subtyping Parasites in Wastewater

Background

Despite their wide occurrence, cryptosporidiosis and giardiasis are considered neglected diseases by the World Health Organization. The epidemiology of these diseases and microsporidiosis in humans in developing countries is poorly understood. The high concentration of pathogens in raw sewage makes the characterization of the transmission of these pathogens simple through the genotype and subtype analysis of a small number of samples.

Methodology/Principal Findings

The distribution of genotypes and subtypes of Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi in 386 samples of combined sewer systems from Shanghai, Nanjing and Wuhan and the sewer system in Qingdao in China was determined using PCR-sequencing tools. Eimeria spp. were also genotyped to assess the contribution of domestic animals to Cryptosporidium spp., G. duodenalis, and E. bieneusi in wastewater. The high occurrence of Cryptosporidium spp. (56.2%), G. duodenalis (82.6%), E. bieneusi (87.6%), and Eimeria/Cyclospora (80.3%) made the source attribution possible. As expected, several human-pathogenic species/genotypes, including Cryptosporidium hominis, Cryptosporidium meleagridis, G. duodenalis sub-assemblage A-II, and E. bieneusi genotype D, were the dominant parasites in wastewater. In addition to humans, the common presence of Cryptosporidium spp. and Eimeria spp. from rodents indicated that rodents might have contributed to the occurrence of E. bieneusi genotype D in samples. Likewise, the finding of Eimeria spp. and Cryptosporidium baileyi from birds indicated that C. meleagridis might be of both human and bird origins.

Conclusions/Significance

The distribution of Cryptosporidium species, G. duodenalis genotypes and subtypes, and E. bieneusi genotypes in urban wastewater indicates that anthroponotic transmission appeared to be important in epidemiology of cryptosporidiosis, giardiasis, and microsporidiosis in the study areas. The finding of different distributions of subtypes between Shanghai and Wuhan was indicative of possible differences in the source of C. hominis among different areas in China.     

Antimicrobial Resistance of Enterococcus Species Isolated from Produce

The purpose of this study was to characterize the antibiotic resistance profiles of Enterococcus species isolated from fresh produce harvested in the southwestern United States. Among the 185 Enterococcus isolates obtained, 97 (52%) were Enterococcus faecium, 38 (21%) were Enterococcus faecalis, and 50 (27%) were other Enterococcus species. Of human clinical importance, E. faecium strains had a much higher prevalence of resistance to ciprofloxacin, tetracycline, and nitrofurantoin than E. faecalis. E. faecalis strains had a low prevalence of resistance to antibiotics used to treat E. faecalis infections of both clinical and of agricultural relevance, excluding its intrinsic resistance patterns. Thirty-four percent of the isolates had multiple-drug-resistance patterns, excluding intrinsic resistance. Data on the prevalence and types of antibiotic resistance in Enterococcus species isolated from fresh produce may be used to describe baseline antibiotic susceptibility profiles associated with Enterococcus spp. isolated from the environment. The data collected may also help elucidate the role of foods in the transmission of antibiotic-resistant strains to human populations.     

Diversity of Microsporidia,Cryptosporidium and Giardia in Mountain Gorillas (Gorilla beringei beringei) in Volcanoes National Park,Rwanda

Background

Infectious diseases represent the greatest threats to endangered species, and transmission from humans to wildlife under increased anthropogenic pressure has been always stated as a major risk of habituation.

Aims

To evaluate the impact of close contact with humans on the occurrence of potentially zoonotic protists in great apes, one hundred mountain gorillas (Gorilla beringei beringei) from seven groups habituated either for tourism or for research in Volcanoes National Park, Rwanda were screened for the presence of microsporidia, Cryptosporidium spp. and Giardia spp. using molecular diagnostics.

Results

The most frequently detected parasites were Enterocytozoon bieneusi found in 18 samples (including genotype EbpA, D, C, gorilla 2 and five novel genotypes gorilla 4–8) and Encephalitozoon cuniculi with genotype II being more prevalent (10 cases) compared to genotype I (1 case). Cryptosporidium muris (2 cases) and C. meleagridis (2 cases) were documented in great apes for the first time. Cryptosporidium sp. infections were identified only in research groups and occurrence of E. cuniculi in research groups was significantly higher in comparison to tourist groups. No difference in prevalence of E. bieneusi was observed between research and tourist groups.

Conclusion

Although our data showed the presence and diversity of important opportunistic protists in Volcanoes gorillas, the source and the routes of the circulation remain unknown. Repeated individual sampling, broad sampling of other hosts sharing the habitat with gorillas and quantification of studied protists would be necessary to acquire more complex data.     

Between-year variation and spatial dynamics of Cryptosporidium spp. and Giardia spp. infections in naturally infected rodent populations

Prevalence and abundance of Cryptosporidium spp. and Giardia spp. infections were studied over the 8-year period in 3 species of rodents in N.E. Poland (bank vole Myodes glareolus-1523; yellow-necked mouse Apodemus flavicollis- 638; common vole Microtus arvalis- 419). Prevalence was 53.8, 28.1 and 62.3% respectively for Cryptosporidium spp. and 58.3, 24.4 and 74.2% respectively for Giardia spp. Prevalence and abundance of infection varied markedly across 8 years of the study with 1998 and 2002 being years of higher prevalence and abundance, following changes in the densities of host species. The distribution of intestinal protozoa in forest rodents did not vary in the 3 isolated sites during the 4-year study. In the case of Cryptosporidium, fewer older animals carried infection and infections of the oldest bank and common voles were relatively milder. In the case of Giardia in yellow-necked mice, infections were more common in older age classes (2 and 3). The two species showed significant co-occurrence and in animals carrying both species there was a strong significant positive correlation between abundance of infection with each. These data are discussed in relation to the parasite genotypes identified in this region and in respect of the role of various ecological factors in shaping of intestinal protozoa communities.     

Epidemiology of Pathogenic Enterobacteria in Humans,Livestock, and Peridomestic Rodents in Rural Madagascar

Background

Among the families of enteric bacteria are globally important diarrheal agents. Despite their potential for zoonotic and environmental transmission, few studies have examined the epidemiology of these pathogens in rural systems characterized by extensive overlap among humans, domesticated and peridomestic animals. We investigated patterns of infection with Enterotoxigenic Escherichia coli, Shigella spp., Salmonella enterica, Vibrio cholerae, and Yersinia spp. (enterocolitica, and pseudotuberculosis) in Southeastern Madagascar where the potential for the aforementioned interactions is high. In this pilot project we conducted surveys to examine behaviors potentially associated with risk of infection and if infection with specific enterobacteria species was associated with diarrheal disease.

Methodology/Principal Findings

PCR was conducted on DNA from human, livestock, and rodent fecal samples from three villages. Overall, human prevalence was highest (77%), followed by rodents (51%) and livestock (18%). Rodents were ∼2.8 times more likely than livestock to carry one of the bacteria. The incidence of individual species varied between villages, with the observation that, E. coli and Shigella spp. were consistently associated with co-infections. As an aggregate, there was a significant risk of infection linked to a water source in one village. Individually, different pathogens were associated with certain behaviors, including: those who had used medication, experienced diarrhea in the past four weeks, or do not use toilets.

Conclusions/Significance

Different bacteria were associated with an elevated risk of infection for various human activities or characteristics. Certain bacteria may also predispose people to co-infections. These data suggest that a high potential for transmission among these groups, either directly or via contaminated water sources. As these bacteria were most prevalent in humans, it is possible that they are maintained in humans and that transmission to other species is infrequent. Further studies are needed to understand bacterial persistence, transmission dynamics, and associated consequences in this and similar systems.     

Tick-Borne Rickettsial Pathogens in Ticks and Small Mammals in Korea

In order to investigate the prevalence of tick-borne infectious agents among ticks, ticks comprising five species from two genera (Hemaphysalis spp. and Ixodes spp.) were screened using molecular techniques. Ticks (3,135) were collected from small wild-caught mammals or by dragging/flagging in the Republic of Korea (ROK) and were pooled into a total of 1,638 samples (1 to 27 ticks per pool). From the 1,638 tick samples, species-specific fragments of Anaplasma phagocytophilum (1 sample), Anaplasma platys (52 samples), Ehrlichia chaffeensis (29 samples), Ehrlichia ewingii (2 samples), Ehrlichia canis (18 samples), and Rickettsia rickettsii (28 samples) were amplified by PCR assay. Twenty-one pooled and individual tick samples had mixed infections of two (15 samples) or three (6 samples) pathogens. In addition, 424 spleen samples from small captured mammals (389 rodents, 33 insectivores, and 2 weasels) were screened for selected zoonotic pathogens. Species-specific DNA fragments of A. phagocytophilum (110 samples), A. platys (68 samples), E. chaffeensis (8 samples), E. ewingii (26 samples), E. canis (51 samples), and Rickettsia sp. (22 samples) were amplified by PCR assay. One hundred thirty small mammals had single infections, while 4, 14, and 21 striped field mice (Apodemus agrarius) had mixed infections of four, three, and two pathogens, respectively. Phylogenetic analysis based on nucleotide sequence comparison also revealed that Korean strains of E. chaffeensis clustered closely with those from China and the United States, while the Rickettsia (rOmpA) sequences clustered within a clade together with a Chinese strain. These results suggest that these agents should be considered in differential diagnosis while examining cases of acute febrile illnesses in humans as well as animals in the ROK.