Several confirmed and probable zoonotic cases of toxigenic Corynebacterium ulcerans, Queensland, Australia

Background

Toxigenic Corynebacterium ulcerans is an emerging zoonosis globally, causing both cutaneous and respiratory diphtheria-like illness. In Queensland, human infection with toxigenic C. ulcerans is rare, with only three cases reported before October 2015. This case series describes five subsequent cases of toxigenic C. ulcerans in Queensland with links to companion animals.

Methods

All data were collected as part of routine public health response, and strains were whole genome sequenced for further characterisation. Household contacts were screened, treated with appropriate antibiotics, and received a diphtheria toxoid-containing vaccine if more than five years had elapsed since their last dose.

Findings

No epidemiological or genomic links could be established between any of the five patients, including between the two cases notified from the same locality within eight days of each other. The C. ulcerans strains from Cases Two, Four and Five were closely related to the strains isolated from their respective pets by whole genome sequencing. Domestic dogs were identified as the most likely mode of transmission for Cases One and Three; however, this was unable to be laboratory confirmed, since Case One's dog was treated with antibiotics before it could be tested, and Case Three's dog was euthanised and cremated prior to case notification.

Interpretation

These are the first reported Australian cases of this emerging zoonosis with links to companion animals. These cases demonstrate the likely transmission route between companion animals and humans, with no evidence of human-to-human transmission. The existing requirement in the Queensland Health Public Health Management Guidelines, of restrictions on cases and some contacts while awaiting swab results, is currently under review.

Detection of Streptococcus pyogenes M1UK in Australia and characterization of the mutation driving enhanced expression of superantigen SpeA

A new variant of Streptococcus pyogenes serotype M1 (designated 'M1_UK') has been reported in the United Kingdom, linked with seasonal scarlet fever surges, marked increase in invasive infections, and exhibiting enhanced expression of the superantigen SpeA. The progenitor S. pyogenes 'M1_global' and M1_UK clones can be differentiated by 27 SNPs and 4 indels, yet the mechanism for speA upregulation is unknown. Here we investigate the previously unappreciated expansion of M1_UK in Australia, now isolated from the majority of serious infections caused by serotype M1 S. pyogenes. M1_UK sub-lineages circulating in Australia also contain a novel toxin repertoire associated with epidemic scarlet fever causing S. pyogenes in Asia. A single SNP in the 5' transcriptional leader sequence of the transfer-messenger RNA gene ssrA drives enhanced SpeA superantigen expression as a result of ssrA terminator read-through in the M1_UK lineage. This represents a previously unappreciated mechanism of toxin expression and urges enhanced international surveillance.

High coverage of diverse invasive meningococcal serogroup B strains by the 4-component vaccine 4CMenB in Australia, 2007-2011: Concordant predictions between MATS and genetic MATS

Meningococcal serogroup B (MenB) accounts for an important proportion of invasive meningococcal disease (IMD). The 4-component vaccine against MenB (4CMenB) is composed of factor H binding protein (fHbp), neisserial heparin-binding antigen (NHBA), Neisseria adhesin A (NadA), and outer membrane vesicles of the New Zealand strain with Porin 1.4. A meningococcal antigen typing system (MATS) and a fully genomic approach, genetic MATS (gMATS), were developed to predict coverage of MenB strains by 4CMenB. We characterized 520 MenB invasive disease isolates collected over a 5-year period (January 2007-December 2011) from all Australian states/territories by multilocus sequence typing and estimated strain coverage by 4CMenB. The clonal complexes most frequently identified were ST-41/44 CC/Lineage 3 (39.4%) and ST-32 CC/ET-5 CC (23.7%). The overall MATS predicted coverage was 74.6% (95% coverage interval: 61.1%-85.6%). The overall gMATS prediction was 81.0% (lower-upper limit: 75.0-86.9%), showing 91.5% accuracy compared with MATS. Overall, 23.7% and 13.1% (MATS) and 26.0% and 14.0% (gMATS) of isolates were covered by at least 2 and 3 vaccine antigens, respectively, with fHbp and NHBA contributing the most to coverage. When stratified by year of isolate collection, state/territory and age group, MATS and gMATS strain coverage predictions were consistent across all strata. The high coverage predicted by MATS and gMATS indicates that 4CMenB vaccination may have an impact on the burden of MenB-caused IMD in Australia. gMATS can be used in the future to monitor variations in 4CMenB strain coverage over time and geographical areas even for non-culture confirmed IMD cases.

Genomic Characterization of Recent and Historic Meningococcal Serogroup E Invasive Disease in Australia: A Case Series

We report the recent emergence of invasive meningococcal disease due to serogroup E in Queensland, Australia, in previously healthy patients. Molecular typing revealed the genotype of these strains to be E:P1.21-7,16:F5-36:ST-1157 (cc1157); when analyzed phylogenetically, compared with international cc1157 strains, they were relatively unrelated to each other.

Mass prophylaxis in an outbreak of invasive group A streptococcal disease in a residential aged care facility

In September 2016, an invasive group A streptococcal disease outbreak occurred among residents of a residential aged care facility. An expert advisory group recommended mass prophylaxis for residents and staff in addition to strict infection control practices to prevent further spread. Whole genome sequencing confirmed the cases were related.

Mild Illness during Outbreak of Shiga Toxin-Producing Escherichia coli O157 Infections Associated with Agricultural Show, Australia

During a large outbreak of Shiga toxin−producing Escherichia coli illness associated with an agricultural show in Australia, we used whole-genome sequencing to detect an IS1203v insertion in the Shiga toxin 2c subunit A gene of Shiga toxin−producing E. coli. Our study showed that clinical illness was mild, and hemolytic uremic syndrome was not detected.

Sequence Analysis of Toxin Gene-Bearing Corynebacterium diphtheriae Strains, Australia

By conducting a molecular characterization of Corynebacterium diphtheriae strains in Australia, we identified novel sequences, nonfunctional toxin genes, and 5 recent cases of toxigenic cutaneous diphtheria. These findings highlight the importance of extrapharyngeal infections for toxin gene-bearing (functional or not) and non-toxin gene-bearing C. diphtheriae strains. Continued surveillance is recommended.

Changing epidemiology of invasive meningococcal disease in Australia 1994–2016

Invasive meningococcal disease (IMD) has a relatively low incidence in Australia, however remains a serious public health issue, with a case fatality rate of approximately 10% despite antimicrobial treatment. IMD is particularly seen in young children, but can affect all age groups. The disease has non-specific early symptoms, rapid clinical progression mainly manifesting as septicaemia and/or meningitis, and has the potential for long term sequelae in the survivors, including skin scarring, amputation, deafness and seizures. There are 13 serogroups, although most invasive infections worldwide are caused by serogroups A, B, C, W, and Y, with some recent outbreaks in Africa caused by serogroup X. The prevalent circulating serogroups can undergo dynamic shifts, generating dramatic changes in IMD epidemiology. Such serogroup shifts have important ramifications for vaccination programs and constant surveillance is crucial.

Public Health

This issue of Microbiology Australia looks at some evolving aspects of microbiology as it relates to Public Health in Australia.

Real-time PCR detection of Neisseria gonorrhoeae susceptibility to penicillin

OBJECTIVES

The objective of this study was to develop a real-time PCR assay targeting the gonococcal porB gene (PorB-PCR) for predicting susceptibility of Neisseria gonorrhoeae to penicillin. This complements a previously described PCR assay for detecting penicillinase-producing N. gonorrhoeae (PPNG) developed by our laboratory (PPNG-PCR).

METHODS

The PorB-PCR assay was designed using six probes to characterize various combinations of amino acids at positions 101 and 102 of the PorB1b class protein, including the WT G101/A102 and mutant G101K/A102D, G101K/A102N and G101K/A102G sequences, as well as the PorB1a sequence. The ability of these sequences to predict penicillin susceptibility was initially assessed using 2307 N. gonorrhoeae isolates from throughout Australia for which phenotypic susceptibility data were available. The assay was then applied to N. gonorrhoeae-positive clinical specimens (n = 70). Specificity was assessed by testing commensal Neisseria strains (n = 75) and N. gonorrhoeae-negative clinical specimens (n = 171).

RESULTS

Testing of the 2307 N. gonorrhoeae isolates using PorB-PCR to detect G101/A102 and PorB1a sequences identified a total of 78.4% (61.2% and 17.2%, respectively) of penicillin-susceptible isolates with specificities of 97.4% and 99.3% and positive predictive values of 98.8% and 98.9%, where PPNG strains were simultaneously identified and excluded. Similar performance data were obtained when the PorB-PCR assay was applied to the N. gonorrhoeae-positive clinical specimens. No false-positive results were observed for the N. gonorrhoeae-negative samples and no cross-reactions were observed with the non-gonococcal species.

CONCLUSIONS

When used in parallel with the previously described PPNG-PCR, the PorB-PCR approach has the potential to facilitate individualized treatment of gonorrhoea using penicillin.

Mutual exclusivity of hyaluronan and hyaluronidase in invasive group A Streptococcus

A recent analysis of group A Streptococcus (GAS) invasive infections in Australia has shown a predominance of M4 GAS, a serotype recently reported to lack the antiphagocytic hyaluronic acid (HA) capsule. Here, we use molecular genetics and bioinformatics techniques to characterize 17 clinical M4 isolates associated with invasive disease in children during this recent epidemiology. All M4 isolates lacked HA capsule, and whole genome sequence analysis of two isolates revealed the complete absence of the hasABC capsule biosynthesis operon. Conversely, M4 isolates possess a functional HA-degrading hyaluronate lyase (HylA) enzyme that is rendered nonfunctional in other GAS through a point mutation. Transformation with a plasmid expressing hasABC restored partial encapsulation in wild-type (WT) M4 GAS, and full encapsulation in an isogenic M4 mutant lacking HylA. However, partial encapsulation reduced binding to human complement regulatory protein C4BP, did not enhance survival in whole human blood, and did not increase virulence of WT M4 GAS in a mouse model of systemic infection. Bioinformatics analysis found no hasABC homologs in closely related species, suggesting that this operon was a recent acquisition. These data showcase a mutually exclusive interaction of HA capsule and active HylA among strains of this leading human pathogen.

Extended-spectrum β-lactamase producing Escherichia coli in hospital wastewaters and sewage treatment plants in Queensland, Australia

We investigated the prevalence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in untreated hospital wastewaters and 2 sewage treatment plants (STPs). A collection of 252 ESBL-producing E. coli isolates from hospital wastewater and STPs were typed and tested for resistance to 17 antimicrobial agents and for the presence of integron-associated integrases (intI gene) and ESBL genes. Eighty-nine percent (n = 176) of the ESBL-producing E. coli strains from hospital wastewater were found in more than 1 sample (common types), with 1 common type accounting for 35% of isolates, found in all samples. These strains were also resistant to up to 9 non-β-lactam antibiotics and showed the same pattern of resistance in all samples. More than 73% of the hospital wastewater isolates possessed SHV-type ESBL as opposed to isolates from STPs that carried only CTX-M-type ESBL genes. The prevalence of the intI gene did not differ between the sources of the isolates. Certain ESBL-producing E. coli were dominant in hospital wastewaters. These strains possessed β-lactamase genes that were different from isolates found in STPs. From a public health point of view, the presence of such a high level of ESBL-producing E. coli strains in hospital wastewaters is of great importance.

Multilocus genotype analysis of Escherichia coli O157 isolates from Australia and the United States provides evidence of geographic divergence

Escherichia coli O157 is a food-borne pathogen whose major reservoir has been identified as cattle. Recent genetic information has indicated that populations of E. coli O157 from cattle and humans can differ genetically and that this variation may have an impact on their ability to cause severe human disease. In addition, there is emerging evidence that E. coli O157 strains from different geographical regions may also be genetically divergent. To investigate the extent of this variation, we used Shiga toxin bacteriophage insertion sites (SBI), lineage-specific polymorphisms (LSPA-6), multilocus variable-number tandem-repeat analysis (MLVA), and a tir 255T>A polymorphism to examine 606 isolates representing both Australian and U.S. cattle and human populations. Both uni- and multivariate analyses of these data show a strong association between the country of origin and multilocus genotypes (P < 0.0001). In addition, our results identify factors that may play a role in virulence that also differed in isolates from each country, including the carriage of stx1 in the argW locus uniquely observed in Australian isolates and the much higher frequency of stx2-positive (also referred to as stx2a) strains in the U.S. isolates (4% of Australian isolates versus 72% of U.S. isolates). LSPA-6 lineages differed between the two continents, with the majority of Australian isolates belonging to lineage I/II (LI/II) (LI, 2%; LI/II, 85%; LII, 13%) and the majority of U.S. isolates belonging to LI (LI, 60%; LI/II, 16%; LII, 25%). The results of this study provide strong evidence of phylogeographic structuring of E. coli O157 populations, suggesting divergent evolution of enterohemorrhagic E. coli O157 in Australia and the United States.

Virus-associated apoptosis of blood neutrophils as a risk factor for invasive meningococcal disease

Aims

To quantify a range of haematological indicators of viral infection (leucocyte apoptosis, cytopenia of normal lymphocytes, reactive lymphocyte increase, neutropenia) in patients with recent onset invasive meningococcal disease (IMD), with a view to test the association of viral infection with IMD and identify possible haematological risk factors for its development.

Subjects and methods

88 patients with recent onset IMD, classified on clinical severity as fatal (n=14), septic shock survived (n=26) and no shock (n=48), and 50 healthy controls were studied. Blood film microscopy and leucocyte counts were used to quantify the virus-associated indicators. Cocci-containing neutrophils were also quantified.

Results

All viral parameters were significantly more frequent or higher in patients than controls, with leucocyte apoptosis found only in the patients. A significant gradient in accord with clinical severity was found for neutrophil and lymphocyte apoptosis, neutropenia and cocci-containing neutrophils. Crucially, apoptotic neutrophils did not contain cocci, and cocci-containing neutrophils were not apoptotic.

Conclusions

The correlation between magnitude of neutrophil apoptosis and severity of IMD suggests a cause–effect relationship. We propose that neutrophil apoptosis is more likely a facilitator rather than an effect of IMD for these reasons: (1) apoptotic neutrophils did not contain cocci and cocci-containing neutrophils were not apoptotic, (2) leucocyte apoptosis is a recognised viral effect and (3) Neisseria meningitidis is incapable of producing a Panton–Valentine type leucocidin. The lymphocyte apoptosis which accompanies neutrophil death may contribute to risk by impairing the generation of microbicidal antibody. Leucocyte apoptosis is a morphological expression of viral immunosuppression and, we suggest, is a likely contributor to a range of viral effects.

Waterborne cryptosporidiosis: current status

In the past ten years Cryptosporidium oocysts have been shown to be common contaminants of water, causing at least 19 waterborne outbreaks of cryptosporidiosis which have affected more than 427 000 individuals. Recommended methods for oocyst isolation and enumeration are time-consuming and inefficient and experts state that the absence of Cryptosporidium oocysts in drinking water can never be guaranteed. In the UK alone, a National Research Programme costing pound3 million has been undertaken. Here, Huw Smith and Joan Rose review the current status of knowledge and identify approaches taken by UK and USA Government regulatory bodies in order to reduce the likelihood of waterborne transmission.

Carriage of Shiga-toxigenic Escherichia coli by native marsupials in Australia

Shiga-toxigenic strains of Escherichia coli (STEC) are zoonotic pathogens with human health, meat processing and trade impacts. Cattle are the principal reservoirs of STEC, although other animals can be carriers. The STEC status of Australian native marsupials has not been formatively described to date. The aim of the current study was to investigate carriage of STEC by native Australian marsupials in Southeast Queensland. Faeces from a variety of marsupial species, stratified by gastrointestinal morphology and dietary type, were screened for stx(1), stx(2) and other STEC virulence genes by PCR. Positive samples were cultured to isolate STEC for characterisation. A number of macropods from both captive and wild habitats had evidence of STEC in their faeces. Rates of stx carriage by macropods (8.6%) were comparable, though generally low, compared to cattle. Eastern grey kangaroos had the highest rate of stx presence in faeces (10.3%). Hindgut-fermenting and monogastric marsupials had no evidence of STEC shedding. Based on virulence marker possession and serotype, the human pathogenic potential of isolates was low. This is the first report of Australian marsupials carrying STEC. Australian native macropods may act as reservoirs for STEC strains, but the potential significance to public health and/or livestock epidemiology remains questionable.

Spatial and temporal epidemiology of sporadic human cryptosporidiosis in Scotland

The spatial and temporal epidemiology of human cryptosporidiosis was described by analysing sporadic cases reported in Scotland from 2005 to 2007. Measures of livestock density and human population density were explored as indicators of the geographical variation in prevalence. Cryptosporidium parvum was more common in areas with lower human population densities, with a higher ratio of the number of farms to human inhabitants and with a higher ratio of the number of private water supplies to human inhabitants. Cryptosporidium parvum caused disease in humans in rural areas and in areas with high ruminant livestock density, whereas Cryptosporidium hominis was more common in the more densely human populated areas of Scotland. The association of private water supplies and increased Cryptosporidium reports merits further public health efforts.

Cryptosporidium infection in non-human hosts in Malawi

Of 1346 faecal samples from the Chikwawa and Thyolo districts of Malawi, analysed for the presence of Cryptosporidium oocysts between October 2001 and May 2003, 61.3% were from cattle (29.8% of these were from calves <6 months old). Cryptosporidium oocysts were detected during all three seasons studied in Chikwawa and Thyolo. In Chikwawa, 13.6% of adult cattle and 11.7% of calves were infected, compared to 28.9% of adult cattle and 36.7% of calves in Thyolo. Dependent on season, between 7.8% and 37.7% (Chikwawa) and 16.7% and 39.3% (Thyolo) of cattle samples contained oocysts. In Chikwawa, the highest percentage of infections occurred in the cool season, whereas in Thyolo, the highest percentage of infections occurred in the dry season. Faecal samples from goats [n=225], pigs [n=92], sheep [n=6]), rabbits, guinea pigs, chickens, ducks, turkeys, doves and guinea fowls were also analysed. Up to 5.6% of goat samples contained oocysts in Chikwawa, compared to between 16.7% and 39.3% in Thyolo. Again, in Chikwawa, the highest percentage of infections occurred in the cool season and the lowest in the rainy season, whereas, in Thyolo, the highest percentage of infections occurred in the dry season and the lowest in the cool season. In pigs, more infections were detected in the dry season in Chikwawa, but infections in the cool season were similar (17.7%), whereas in Thyolo, infections occurred in all three seasons (17.9% in the rainy season, 25% in the cool season and 60% in the dry season). Of ten diarrhoeic, oocyst positive cattle faecal samples collected from Chikwawa and subjected to PCR-RFLP, four oocyst positive samples (two from heifers, one from a cow and one unknown) were amplified at an 18S rRNA and Cryptosporidium oocyst wall protein (COWP) loci. RFLP of the 18S rRNA locus indicated that Cryptosporidium parvum, Cryptosporidium hominis, Cryptosporidium bovis and/or Cryptosporidium ryanae DNA, or a mixture of them was present. Cryptosporidium parvum DNA was identified in one sample that amplified at the COWP locus, indicating the presence of the major zoonotic Cryptosporidium species in Malawi.

Effects of Preservatives on Viability of Cryptosporidium parvum Oocysts

Potassium dichromate and formalin reduced the viability of Cryptosporidium parvum oocysts as assessed by inclusion or exclusion of 4',6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI) and excystation. Some formalin-treated oocysts containing dead sporozoites excluded PI; that this fluorogenic assay relies not solely upon exclusion of PI but also upon highlighting of sporozoite nuclei by DAPI is reiterated.

An outbreak of shiga toxin-producing Escherichia coli infection associated with a school camp

In November 2008, a case of Shiga toxin-producing Escherichia coli (STEC) infection was reported to the Brisbane Southside Public Health Unit. The case had participated in a school camp. Subsequent investigations confirmed 5 other asymptomatic cases among camp attendees or visitors. Examination of the camp water supply identified that most water sources had high levels of E. coli and did not meet the Australian Drinking Water Guidelines with STEC isolated from 2 water sources. This outbreak highlights the emerging issue of asymptomatic carriage of STEC and the importance of thorough maintenance and attention to drinking water supplies in the rural and school camp setting.

Cryptosporidium oocysts on fresh produce from areas of high livestock production in Poland

Samples of fresh vegetables and soft fruit were collected from farmers' markets in the Lublin Area of Poland during 2006-2007; the produce was grown in areas of high to moderate livestock production. Cryptosporidium sp. oocysts were eluted from food surfaces, separated from residual food materials by IMS and identified by immunofluorescence and Nomarski differential interference contrast microscopy. Cryptosporidium sp. oocysts were detected in 6 of 128 vegetable samples (range 1-47 oocysts), but not in any of 35 fruit samples. Both empty and intact oocysts were detected. Species identity of oocyst-positive samples was performed by molecular analysis at four genetic loci. One of two 18S rRNA loci amplified DNA from 5 of the 6 oocyst-positive samples, but insufficient DNA for RFLP or sequencing analysis was available from 4 of these samples. An oocyst-positive celery sample generated an RFLP pattern consistent with C. parvum at two loci, but insufficient DNA was available for subtyping (GP60 sequencing) this isolate. Oocyst-contaminated foods originated from districts with the highest numbers of homesteads possessing cattle herds and no contaminated produce was detected from districts containing lower numbers of cattle-owning homesteads, strengthening the assumption that the origin of the contamination was livestock. The results of this study strengthen the evidence for the potential for zoonotic foodborne transmission of Cryptosporidium.

Genetic relatedness and virulence gene profiles of Escherichia coli strains isolated from septicaemic and uroseptic patients

We investigated the relationship between clonality and virulence factors (VFs) of a collection of Escherichia coli strains isolated from septicaemic and uroseptic patients with respect to their origin of translocation. Forty septicaemic and 30 uroseptic strains of E. coli were tested for their phylogenetic groupings, genetic relatedness using randomly amplified polymorphic DNA (RAPD), biochemical fingerprinting method (biochemical phenotypes [BPTs]), adherence to HT-29 cells and the presence of 56 E. coli VF genes. Strains belonging to phylogenetic groups B2 and D constituted 93% of all strains. Fifty-four (77%) strains belonged to two major BPT/RAPD clusters (A and B), with cluster A carrying significantly (P = 0.0099) more uroseptic strains. The degree of adhesion to HT-29 cells of uroseptic strains was significantly (P = 0.0012) greater than that of septicaemic strains. Of the 56 VF genes tested, pap genes was the only group that were found significantly (P < 0.0001) more often among uroseptic isolates. Phylogenetic group B2 contained a significantly higher number of strains carrying pap genes than those in group D. We conclude that uroseptic E. coli are clonally different from septicaemic strains, carry more pap genes and predominantly adhere more to the HT-29 cell model of the gut.

Intestinal parasitic infections amongst Orang Asli (indigenous) in Malaysia: has socioeconomic development alleviated the problem?

Orang Asli are the indigenous minority peoples of peninsular Malaysia. Despite proactive socioeconomic development initiated by the Malaysian Government in upgrading the quality of life of the Orang Asli communities since 1978, they still remained poor with a current poverty rate of 76.9%. Poverty exacerbates the health problems faced by these communities which include malnourishment, high incidences of infectious diseases (eg. tuberculosis, leprosy, malaria) and the perpetual problem with intestinal parasitic infections. Studies reported that the mean infection rate of intestinal parasitic infections in Orang Asli communities has reduced from 91.1% in 1978, to 64.1% in the subsequent years. Although the results was encouraging, it has to be interpreted with caution because nearly 80% of studies carried out after 1978 still reported high prevalence (i.e. >50%) of soil-transmitted helminthiases (STH) among Orang Asli communities. Prior to 1978, hookworm infection is the most predominant STH but today, trichuriasis is the most common STH infections. The risk factors for intestinal parasitic infections remained unchanged and studies conducted in recent years suggested that severe STH infections contributed to malnutrition, iron deficiency anaemia and low serum retinol in Orang Asli communities. In addition, STH may also contribute to poor cognitive functions and learning ability. Improvements in socioeconomic status in Malaysia have shown positive impact on the reduction of intestinal parasitic infections in other communities however, this positive impact is less significant in the Orang Asli communities. In view of this, a national parasitic infections baseline data on morbidity and mortality in the 18 subgroups of Orang Asli, will assist in identifying intervention programmes required by these communities. It is hope that the adoption of strategies highlighted in the World Health Organisation- Healthy Village Initiatives (WHO-HVI) into Orang Asli communities will ensure the whole mechanism of delivery and empowerment by the government agencies become more efficient and productive in alleviating intestinal parasitic infections in these communities.

Intestinal parasitic infections in HIV/AIDS patients presenting with diarrhoea in Jakarta, Indonesia

We investigated the occurrence of intestinal parasites in Indonesian HIV/AIDS patients with chronic diarrhoea prior to administering antiretroviral therapy. The influence of age, CD4(+) cell count and season on parasite occurrence was also studied. In total, 318 unconcentrated stool samples were analysed using Lugol's iodine and modified acid fast staining to detect intestinal coccidia. Most samples (94.5%) were from males aged 21-40 years with CD4(+) counts < or = 50 cells/mm(3). Parasites were found in 84.3% of samples (single species infections, 71.4%; polyparasitism, 12.9%), with protozoan pathogens occurring most commonly. Cryptosporidium (4.9%), Cyclospora cayetanensis (4.5%) and Giardia duodenalis (1.9%) were the most frequent single infections, but Blastocystis hominis (72.4%) was the most commonly occurring protist. Cryptosporidium and C. cayetanensis occurred in 11.9% and 7.8% of all (single and mixed) infections. The most common co-infection was with B. hominis and Cryptosporidium (6.3%). Intestinal protozoan pathogens were detected more frequently in cases with CD4(+) counts < or = 200/mm(3). No seasonal influence was determined for Cryptosporidium, C. cayetanensis or B. hominis, but gross seasonal disturbances may have influenced our findings. Intestinal parasites should be looked for routinely in this group of individuals and should be treated to reduce complications and the likelihood of transmission.

Phenotypic and genotypic characterisation of Blastocystis hominis isolates implicates subtype 3 as a subtype with pathogenic potential

Despite frequent reports on the presence of Blastocystis hominis in human intestinal tract, its pathogenicity remains a matter of intense debate. These discrepancies may be due to the varying pathogenic potential or virulence of the isolates studied. The present study represents the first to investigate both phenotypic and genotypic characteristics of B. hominis obtained from symptomatic and asymptomatic individuals. Symptomatic isolates had a significantly greater size range and lower growth rate in Jones' medium than asymptomatic isolates. The parasite cells of symptomatic isolates exhibited rougher surface topography and greater binding affinity to Canavalia ensiformis (ConA) and Helix pomatia (HPA). The present study also identifies further phenotypic characteristics, which aided in differentiating the pathogenic forms from the non-pathogenic forms of B. hominis. Blastocystis subtype 3 was found to be correlated well with the disease.

Cercarial dermatitis in the UK

'Swimmer's itch' or cercarial dermatitis (CD) results from an immunological reaction to free-swimming non-human schistosome parasites released from aquatic snails. Affected bathers develop a self-limiting, pruritic, macular or papular eruption shortly after leaving the water. The condition is well-recognized in continental Europe, Asia and America, but has not to date been recorded in the UK.

Current status and future trends in Cryptosporidium and Giardia epidemiology in Malaysia

Cryptosporidium and Giardia are major causes of diarrhoeal diseases of humans worldwide, and are included in the World Health Organisation's 'Neglected Diseases Initiative'. Cryptosporidium and Giardia occur commonly in Malaysian human and non-human populations, but their impact on disease, morbidity and cost of illness is not known. The commonness of contributions from human (STW effluents, indiscriminate defaecation) and non-human (calving, lambing, muck spreading, slurry spraying, pasturing/grazing of domestic animals, infected wild animals) hosts indicate that many Malaysian environments, particularly water and soil, are sufficiently contaminated to act as potential vehicles for the transmission of disease. To gain insight into the morbidity and mortality caused by human cryptosporidiosis and giardiasis, they should be included into differential diagnoses, and routine laboratory testing should be performed and (as for many infectious diseases) reported to a centralised public health agency. To understand transmission routes and the significance of environmental contamination better will require further multidisciplinary approaches and shared resources, including raising national perceptions of the parasitological quality of drinking water. Here, the detection of Cryptosporidium and Giardia should be an integral part of the water quality requirement. A multidisciplinary approach among public health professionals in the water industry and other relevant health- and environment-associated agencies is also required in order to determine the significance of Cryptosporidium and Giardia contamination of Malaysian drinking water. Lastly, adoption of validated methods to determine the species, genotype and subgenotype of Cryptosporidium and Giardia present in Malaysia will assist in developing effective risk assessment, management and communication models.

Cryptosporidium--biotechnological advances in the detection, diagnosis and analysis of genetic variation

Cryptosporidiosis is predominantly a gastrointestinal disease of humans and other animals, caused by various species of protozoan parasites representing the genus Cryptosporidium. This disease, transmitted mainly via the faecal-oral route (in water or food), is of major socioeconomic importance worldwide. The diagnosis and genetic characterization of the different species and population variants (usually recognised as "genotypes" or "subgenotypes") of Cryptosporidium is central to the prevention, surveillance and control of cryptosporidiosis, particularly given that there is presently no broadly applicable treatment regimen for this disease. Although traditional phenotypic techniques have had major limitations in the specific diagnosis of cryptosporidiosis, there have been major advances in the development of molecular analytical and diagnostic tools. This article provides a concise account of Cryptosporidium and cryptosporidiosis, and focuses mainly on recent advances in nucleic acid-based approaches for the diagnosis of cryptosporidiosis and analysis of genetic variation within and among species of Cryptosporidium. These advances represent a significant step toward an improved understanding of the epidemiology as well as the prevention and control of cryptosporidiosis.

The effect of blueberry extracts on Giardia duodenalis viability and spontaneous excystation of Cryptosporidium parvum oocysts, in vitro

The protozoan parasites Giardia duodenalis and Cryptosporidium parvum are common causes of diarrhoea, worldwide. Effective drug treatment is available for G. duodenalis, but with anecdotal evidence of resistance or reduced compliance. There is no effective specific chemotherapeutic intervention for Cryptosporidium. Recently, there has been renewed interest in the antimicrobial properties of berries and their phenolic compounds but little work has been done on their antiparasitic actions. The effect of various preparations of blueberry (Vaccinium myrtillus) extract on G. duodenalis trophozoites and C. parvum oocysts were investigated. Pressed blueberry extract, a polyphenolic-rich blueberry extract, and a commercially produced blueberry drink (Bouvrage) all demonstrated antigiardial activity. The polyphenol-rich blueberry extract reduced trophozoite viability in a dose dependent manner. At 167 microgml(-1), this extract performed as well as all dilutions of pressed blueberry extract and the Bouvrage beverage (9.6+/-2.8% live trophozoites remaining after 24h incubation). The lowest dilution of blueberry extract tested (12.5% v/v) contained >167 microgml(-1) of polyphenolic compounds suggesting that polyphenols are responsible for the reduced survival of G. duodenalis trophozoites. The pressed blueberry extract, Bouvrage beverage and the polyphenolic-rich blueberry extract increased the spontaneous excystation of C. parvum oocysts at 37 degrees C, compared to controls, but only at a dilution of 50% Bouvrage beverage, equivalent to 213 microgml(-1) gallic acid equivalents in the polyphenolic-rich blueberry extract. Above this level, spontaneous excystation is decreased. We conclude that water soluble extracts of blueberries can kill G. duodenalis trophozoites and modify the morphology of G. duodenalis and C. parvum.

Development of a method for detection of Giardia duodenalis cysts on lettuce and for simultaneous analysis of salad products for the presence of Giardia cysts and Cryptosporidium oocysts

We report a method for detecting Giardia duodenalis cysts on lettuce, which we subsequently use to examine salad products for the presence of Giardia cysts and Cryptosporidium oocysts. The method is based on four basic steps: extraction of cysts from the foodstuffs, concentration of the extract and separation of the cysts from food materials, staining of the cysts to allow their visualization, and identification of cysts by microscopy. The concentration and separation steps are performed by centrifugation, followed by immunomagnetic separation using proprietary kits. Cyst staining is also performed using proprietary reagents. The method recovered 46.0% +/- 19.0% (n = 30) of artificially contaminating cysts in 30 g of lettuce. We tested the method on a variety of commercially available natural foods, which we also seeded with a commercially available internal control, immediately prior to concentration of the extract. Recoveries of the Texas Red-stained Giardia cyst and Cryptosporidium oocyst internal controls were 36.5% +/- 14.3% and 36.2% +/- 19.7% (n = 20), respectively. One natural food sample of organic watercress, spinach, and rocket salad contained one Giardia cyst 50 g(-1) of sample as an indigenous surface contaminant.

Effect of various environmental factors on the viability of Cryptosporidium parvum oocysts

AIMS

To evaluate individual and combined effects of temperature (4, 18 and 25 degrees C), pH (7 and 10), ammonia (5 and 50 mg l(-1)) and exposure time (1, 2, 4 and 6 days) on the viability of Cryptosporidium parvum oocysts in water.

METHODS AND RESULTS

The viability of oocysts was evaluated using the fluorogenic vital dyes assay (4',6-diamidino-2-phenylindole and propidium iodide). All the factors analysed (temperature, pH, ammonia and exposure time) and their interaction were statistically significant (P < 0.005). Exposure of oocysts to pH 10 for 6 days at 25 degrees C reduced oocyst viability from approximately 80% to 51%. Similarly, the exposure of C. parvum oocysts to 5 mg NH(3) l(-1) and 50 mg NH(3) l(-1) for 4 days reduced their viability from between approximately 80% to 41.5% and 14.8%, respectively.

CONCLUSIONS

The interaction between pH, temperature and exposure time may have adverse effects on the survival of C. parvum oocysts in water. Low concentrations of ammonia, as commonly found in alga-based wastewater systems, over a long period of time can produce high C. parvum oocyst inactivation rates.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides relevant data on the inactivation of C. parvum oocysts in alga-based wastewater-treatment systems in the northwest of Spain.

Cryptosporidium and Giardia as foodborne zoonoses

Cryptosporidium and Giardia are major causes of diarrhoeal disease in humans, worldwide and are major causes of protozoan waterborne diseases. Both Cryptosporidium and Giardia have life cycles which are suited to waterborne and foodborne transmission. There are 16 'valid'Cryptosporidium species and a further 33+ genotypes described. Parasites which infect humans belong to the Giardia duodenalis "type", and at least seven G. duodenalis assemblages are recognised. Cryptosporidium parvum is the major zoonotic Cryptosporidium species, while G. duodenalis assemblages A and B have been found in humans and most mammalian orders. In depth studies to determine the role of non-human hosts in the transmission of Cryptosporidium and Giardia to humans are required. The use of harmonised methodology and standardised and validated molecular markers, together with sampling strategies that provide sufficient information about all contributors to the environmental (oo)cyst pool that cause contamination of food and water, are recommended. Standardised methods for detecting (oo)cysts in water are available, as are optimised, validated methods for detecting Cryptosporidium in soft fruit and salad vegetables. These provide valuable data on (oo)cyst occurrence, and can be used for species and subspecies typing using appropriate molecular tools. Given the zoonotic potential of these organisms, epidemiological, source and disease tracking investigations involve multidisciplinary teams. Here, the role of the veterinarian is paramount, particularly in understanding the requirement for adopting comprehensive sampling strategies for analysing both sporadic and outbreak samples from all potential non-human contributors. Comprehensive sampling strategies increase our understanding of parasite population biology and structure and this knowledge can be used to determine what level of discrimination is required between isolates. Genetic exchange is frequent in C. parvum populations, leading to recombination between alleles at different loci, the generation of a very large number of different genotypes and a high level of resolution between isolates. In contrast, genetic exchange appears rare in Cryptosporidium hominis and populations are essentially clonal with far fewer combinations of alleles at different loci, resulting in a much lower resolution between isolates with many being of the same genotype. Clearly, more markers provide more resolution and high throughput sequencing of a variety of genes, as in multilocus sequence typing, is a way forward. Sub-genotyping tools offer increased discrimination, specificity and sensitivity, which can be exploited for investigating the epidemiology of disease, the role of asymptomatic carriers and contaminated fomites and for source and disease tracking for food and water contaminated with small numbers of (oo)cysts.

Prevalence ofCryptosporidiumspecies in intensively farmed pigs in Ireland

NaturalCryptosporidiuminfections in pigs are widespread but generally apathogenic. This study was undertaken to determine the prevalence of zoonoticCryptosporidiumspp. in piggeries in Ireland, where the drinking water supply is particularly vulnerable to contamination with zoonotic species. Overall, infections were detected in 39 out of 342 animals (11·4%), with highest infection rates among weaners (15%) and sows (13·3%). Twenty-nine positive samples were genotyped based on SSU rRNA sequence analysis. Infections withCryptosporidium parvum, the most important zoonotic species were rare and are likely to be of greater concern to animal handlers than suppliers of drinking water. In addition toC. parvum,Cryptosporidium suis,Cryptosporidiumpig genotype II,Cryptosporidium murisand a previously undescribed genotype were identified. ABI-profiles indicated the presence of different alleles in at least 40% of all genotyped isolates. This was confirmed in 3 isolates by cloning of the PCR products. Since chronic mixed infections appear to be quite common in pigs they could be considered as models for mixed infections in immunocompromised humans.

Incidence of cryptosporidiosis species in paediatric patients in Malawi

We determined the incidence of cryptosporidiosis in children aged <5 years presenting with diarrhoea in an urban and rural hospital-based setting in Malawi. Stools were collected over a 22-month period during both rainy and dry seasons. A range of microscopic methods were used to determine the presence of Cryptosporidium spp. oocysts. Species determination was by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of oocyst-extracted DNA using 18S rRNA and COWP gene loci. Cryptosporidium spp. oocysts were seen in 5.9% (50/848) of samples, of which 43 amplified by PCR-RFLP indicated the following species: C. hominis, C. parvum, C. hominis/C. parvum, C. meleagridis and C. andersoni. Seven samples could not be amplified by PCR. Wider species diversity was found in the rural setting, and may be a result of increased malnutrition and zoonotic exposure in this area. Improvements in water, sanitation, household hygiene and animal control are required to reduce the incidence of infection in this population.

Detection of UV-induced thymine dimers in individual Cryptosporidium parvum and Cryptosporidium hominis oocysts by immunofluorescence microscopy

To investigate the effect of UV light on Cryptosporidium parvum and Cryptosporidium hominis oocysts in vitro, we exposed intact oocysts to 4-, 10-, 20-, and 40-mJ x cm-2 doses of UV irradiation. Thymine dimers were detected by immunofluorescence microscopy using a monoclonal antibody against cyclobutyl thymine dimers (anti-TDmAb). Dimer-specific fluorescence within sporozoite nuclei was confirmed by colocalization with the nuclear fluorogen 4',6'-diamidino-2-phenylindole (DAPI). Oocyst walls were visualized using either commercial fluorescein isothiocyanate-labeled anti-Cryptosporidium oocyst antibodies (FITC-CmAb) or Texas Red-labeled anti-Cryptosporidium oocyst antibodies (TR-CmAb). The use of FITC-CmAb interfered with TD detection at doses below 40 mJ x cm-2. With the combination of anti-TDmAb, TR-CmAb, and DAPI, dimer-specific fluorescence was detected in sporozoite nuclei within oocysts exposed to 10 to 40 mJ x cm-2 of UV light. Similar results were obtained with C. hominis. C. parvum oocysts exposed to 10 to 40 mJ x cm-2 of UV light failed to infect neonatal mice, confirming that results of our anti-TD immunofluorescence assay paralleled the outcomes of our neonatal mouse infectivity assay. These results suggest that our immunofluorescence assay is suitable for detecting DNA damage in C. parvum and C. hominis oocysts induced following exposure to UV light.

Cryptosporidium parvum sporozoites contain glutathione

We used the fluorescent dye monochlorobimane (MCB) which binds glutathione (GSH) to localize between 2 and 6 distinctly labelled nuclear and cytoplasmic GSH foci in recently excreted and aged, intact Cryptosporidium parvum oocysts and sporozoites. Buthionine sulfoximine (BSO), a potent and specific inhibitor of GSH, was used to determine whether GSH is synthesized in BSO-treated C. parvum oocysts, by labelling treated oocysts with MCB. Both visual and electronic quantifications were performed. At 5 mM BSO, a significant inhibition of MCB fluorescence, reflecting reduced MCB uptake, was observed in GSH-depleted oocysts (mean +/- S.D. 35 +/- 3.7) compared with controls (3.3 +/- 1.2, P = 0). This clear reduction occurred only in viable oocysts. 1 mM BSO-treated oocysts exhibited weak or no MCB fluorescence, although they were viable (excluded propidium iodide, PI)), and intact and contained sporozoites by differential interference contrast microscopy (DIC). MCB was used in conjunction with PI to determine C. parvum oocyst viability. Oocysts labelled with MCB/PI or 4'6-diamidino-2-phenyl indole (DAPI)/PI produced comparable labelling patterns. Viable oocysts were labelled with MCB or DAPI whereas dead oocysts were labelled with PI only. The localization of GSH in viable, intact oocysts and excysted sporozoites and UV light-irradiated oocysts and sporozoites revealed no changes in MCB uptake at levels up to 40 mJ.cm(-2) irradiation. Although GSH can be detected following MCB localization in both the nucleus and cytoplasm of sporozoites, and can be specifically depleted by BSO treatment, MCB is unlikely to be useful as a surrogate for detecting UV damage in UV-treated Cryptosporidium oocysts.

Towards standard methods for the detection of Cryptosporidium parvum on lettuce and raspberries. Part 2: validation

We report the results of interlaboratory collaborative trials of methods to detect oocysts of the protozoan parasite Cryptosporidium parvum on lettuce and raspberries. The trials involved eight expert laboratories in the United Kingdom. Samples comprised 30 g lettuce, and 60 g raspberries. Lettuce samples were artificially contaminated at three levels: low (8.5-14.2 oocysts), medium (53.5-62.6 oocysts), and high (111.3-135.0 oocysts). Non-contaminated lettuce samples were also tested. The method had an overall sensitivity (correct identification of all artificially contaminated lettuce samples) of 89.6%, and a specificity (correct identification of non-contaminated samples) of 85.4%. The total median percentage recovery (from all artificially contaminated samples) produced by the method was 30.4%. The method was just as reproducible between laboratories, as repeatable within a laboratory. Raspberry samples were artificially contaminated at three levels: low (8.5-26.8 oocysts), medium (29.7-65.7 oocysts), and high (53.9-131.3 oocysts). Non-contaminated raspberry samples were also tested. The method had an overall sensitivity (correct identification of all artificially contaminated raspberry samples) of 95.8%, and a specificity (correct identification of non-contaminated samples) of 83.3%. The total median percentage recovery (from all artificially contaminated samples) produced by the method was 44.3%. The method was just as reproducible between laboratories, as repeatable within a laboratory. The results of the collaborative trial indicate that these assays can be used effectively in analytical microbiological laboratories.

Towards standard methods for the detection of Cryptosporidium parvum on lettuce and raspberries. Part 1: development and optimization of methods

No standard method is available for detecting protozoan parasites on foods such as soft fruit and salad vegetables. We report on optimizing methods for detecting Cryptosporidium parvum on lettuce and raspberries. These methods are based on four basic stages: extraction of oocysts from the foodstuffs, concentration of the extract and separation of the oocysts from food materials, staining of the oocysts to allow their visualization, and identification of oocysts by microscopy. The concentration and separation steps are performed by centrifugation, followed by immunomagnetic separation using proprietary kits. Oocyst staining is also performed using proprietary reagents. The performance parameters of the extraction steps were extensively optimized, using artificially contaminated samples. The fully developed methods were tested several times to determine their reliability. The method to detect C. parvum on lettuce recovered 59.0+/-12.0% (n=30) of artificially contaminated oocysts. The method to detect C. parvum on raspberries recovered 41.0+/-13.0% (n=30) of artificially contaminated oocysts.

PCR fingerprinting of Blastocystis isolated from symptomatic and asymptomatic human hosts

Genomic DNA from 16 Blastocystis hominis isolates comprising of eight asymptomatic isolates (A1-A8) and eight symptomatic isolates (S1-S8) was amplified by arbitrarily primed polymerase chain reaction (AP-PCR) using 38 arbitrary 10-mer primers. Six primers (A10, B5, C20, D1, F6, and F10) generated reproducible DNA fingerprints. AP-PCR amplification revealed similar DNA fingerprints among all symptomatic isolates (S1-S8) with common bands at 850 bp using primer A10, 920 bp using primer B5, and 1.3 kbp using primer D1. Isolates A1, A3, A4, A5, A6, and A7 showed similar DNA banding patterns and all asymptomatic isolates (A1-A8) shared a major band at 1 kbp using primer B5. Isolates A2 and A8 showed distinct DNA banding patterns that differed from the remainder of the isolates. The results of the phylogenetic analyses showed that all symptomatic isolates (S1-S8) formed a clade with >70% similarity among the isolates and which were clearly separate from asymptomatic isolates A1, A3, A4, A5, A6, and A7. Asymptomatic isolates A2 and A8 formed two distinct and separate clades. AP-PCR revealed higher genetic variability within the asymptomatic isolates than within the symptomatic isolates. The present study suggests that AP-PCR can be a valuable method for differentiating between isolates of B. hominis and our results support the hypothesis that our asymptomatic and symptomatic B. hominis isolates may represent two different strains/species with varying pathogenic potential.

Fertilization state of Ascaris suum determined by electrorotation

Electrorotation is a non-invasive technique that is capable of detecting changes in the morphology and physicochemical properties of microorganisms. The first detailed electrorotation study of the egg (ovum) of a parasitic nematode, namely Ascaris suum is described to show that electrorotation can rapidly differentiate between fertilized and non-fertilized eggs. Support for this conclusion is by optical microscopy of egg morphology, and also from modelling of the electrorotational response. Modelling was used to determine differences in the dielectric properties of the unfertilized and fertilized eggs, and also to investigate specific differences in the spectra of fertilized eggs only, potentially reflecting embryogenesis. The potential of electrorotation as an investigative tool is shown, as undamaged eggs can be subjected to further non-destructive and destructive techniques, which could provide further insight into parasite biology and epidemiology.

Viable blastocystis cysts in Scottish and Malaysian sewage samples

Blastocystis cysts were detected in 38% (47/123) (37 Scottish, 17 Malaysian) of sewage treatment works. Fifty percent of influents (29% Scottish, 76% Malaysian) and 28% of effluents (9% Scottish, 60% Malaysian) contained viable cysts. Viable cysts, discharged in effluent, provide further evidence for the potential for waterborne transmission of Blastocystis.