Acanthamoeba keratitis: Molecular typing of Acanthamoeba species directly from ocular tissue.

This report explores the molecular profiling of Acanthamoeba spp. from individuals in the UK suffering from a debilitating, sight-threatening disease of the cornea known as Acanthamoeba keratitis (AK). Seventy ocular samples from individuals undergoing investigations for AK were sent to the Scottish Microbiology Reference Laboratories (SMiRL), Glasgow during 2017-2019, and subjected to DNA extraction followed by in-depth molecular typing using a nested PCR/bi-directional sequencing approach. Of the 70 samples tested, 40 were PCR-positive. Of these, 32 were successfully sequenced and assigned to two of 23 existing genotypes termed T1 to T23. Molecular profiling of the 32 samples highlighted two genotypes, namely T3 (n = 3) and T4 (n = 29). For those 29 samples identified as the T4 genotype, a sub-genotype (T4A-T4H) was recorded: T4A (n = 18); T4B (n = 5); T4C (n = 1); T4E (n = 4); and T4F (n = 1). This study highlights that the T4 genotype and T4A subtype are the predominant molecular variants to cause ocular disease in the UK. Gaining in-depth information on the molecular profiling of Acanthamoeba spp. is essential to increase our understanding of the source(s) of infection, transmission pathways, and potential associations with clinical outcomes for this rare, yet potentially debilitating ocular disease.

Changing Molecular Profiles of Human Cryptosporidiosis Cases in Scotland as a Result of the Coronavirus Disease, COVID-19 Pandemic.

Cryptosporidium, the most frequently reported parasite in Scotland, causes gastrointestinal illness resulting in diarrhoea, nausea and cramps. Two species are responsible for most cases: Cryptosporidium hominis (C. hominis) and Cryptosporidium parvum (C. parvum). Transmission occurs faecal-orally, through ingestion of contaminated food and water, or direct contact with faeces. In 2020, the COVID-19 pandemic led to global restrictions, including national lockdowns to limit viral transmission. Such interventions led to decreased social mixing, and reduced/no local and international travel, which are factors associated with transmission of multiple communicable diseases, including cryptosporidiosis. This report assessed the impact of the pandemic on Scottish cryptosporidiosis cases, and identified changes in circulating molecular variants of Cryptosporidium species. Molecular data generated using real time PCR and GP60 nested-PCR assays on laboratory-confirmed cryptosporidiosis cases reported during 2018-22 were analysed. The Scottish Microbiology Reference Laboratories (SMiRL), Glasgow, received 774 Cryptosporidium-positive faeces during 2018-22, of which 486 samples were successfully subtyped. During this time period, C. hominis (n = 155; 21%) and C. parvum (n = 572; 77%) were the most commonly detected species. The total number of cases during 2020, which was greatly affected by the pandemic, was markedly lower in comparison to case numbers in the 2 years before and after 2020. The most predominant C. hominis family detected prior to 2020 was the Ib family which shifted to the Ie family during 2022. The most common C. parvum variant during 2018-22 was the IIa family, however a rise in the IId family was observed (n = 6 in 2018 to n = 25 in 2022). The dominant C. hominis subtype IbA10G2, which accounted for 71% of C. hominis subtypes in 2018-19 was superseded by three rare subtypes: IeA11G3T3 (n = 15), IdA16 (n = 8) and IbA9G3 (n = 3) by 2022. Frequently reported C. parvum subtypes in 2018-19 were IIaA15G2R1 and IIaA17G1R1, accounting for 59% of total C. parvum subtypes. By 2022, IIaA15G2R1 remained the most common (n = 28), however three unusual subtypes in Scotland emerged: IIdA24G1 (n = 7), IIaA16G3R1 (n = 7) and IIaA15G1R2 (n = 7). Continuous monitoring of Cryptosporidium variants following the pandemic will be essential to explore further changes and emergence of strains with altered virulence.

Molecular characterisation of Giardia duodenalis from human and companion animal sources in the United Kingdom using an improved triosephosphate isomerase molecular marker.

Giardia duodenalis is a protozoan parasite known for its ability to cause gastrointestinal disease in human and non-human mammals. In the UK, the full impact of this parasite has yet to be fully explored, due to the limited testing which has been undertaken in humans and the low-resolution assemblage-typing methods currently available. Rather than being primarily a travel-associated condition, a recent study has highlighted that an endemic Giardia cycle is present in the UK, although the source of human disease is unclear in the majority of cases. This study focussed on the improvement of one of the commonly used assemblage-typing assays, a nested topoisomerase phosphate (tpi) PCR, to increase the amplification success rate across both human and companion animal samples. After comparing published primers to full Giardia reference genomes, this marker protocol was optimised and then deployed to test a substantial number of human (n â€‹= â€‹79) and companion animal (n â€‹= â€‹174) samples to gain an insight into the molecular epidemiology of Giardia in the UK. One assemblage A1 and eleven assemblage A2 genotypes were detected in humans, along with and 25 assemblage B genotypes. Assemblage A1 genotypes, known to be human-infective, were found in three feline and one canine sample, while one feline sample contained assemblage A2. Additionally, four feline samples contained assemblage B, which is recognised as potentially human-infective. This study demonstrates the presence of potentially human-infective Giardia genotypes circulating in the companion animal population, notably with 17.4% (8/46) of feline-derived Giardia strains being potentially zoonotic. Using a modified tpi-based genotyping assay, this work highlights the potential for domestic pets to be involved in the endemic transmission of giardiasis in the UK and underlines the need for appropriate hygiene measures to be observed when interacting with both symptomatic and asymptomatic animals. It also serves to underline the requirement for further studies to assess the zoonotic risk of Giardia associated with companion animals in high-income countries.

Validation of a multilocus genotyping scheme for subtyping Cryptosporidium parvum for epidemiological purposes.

Subtyping Cryptosporidium parvum for outbreak investigations or epidemiological surveillance usually relies on DNA sequence analysis of a gene coding for a 60 KDa glycoprotein (gp60). Although gp60 can be useful for allelic discrimination and to help investigate sources and routes of transmission, the presence of common subtypes and recombination during the parasite's sexual life-cycle demand a multilocus-based method for more discriminatory genotyping. While whole genome sequencing would provide the ultimate approach, it is a time consuming and expensive option for faecal parasites such as Cryptosporidium that occur at low density and are difficult to propagate routinely. In this study, we selected and evaluated a panel of previously identified variable-number tandem-repeat (VNTR) markers, to establish a multilocus genotyping scheme based on fragment sizing, appropriate for inter-laboratory surveillance and outbreak investigations. Seven VNTR markers were validated in vitro and demonstrated typeability of 0.85 and discriminatory power of 0.99. The discriminatory power was much greater than the currently used gp60 sequencing (0.74), which identified 26 subtypes, compared to 100 different MLVA profiles within the same sample set. The assay was robust, with repeatable results and reproducibility across three laboratories demonstrating the scheme was suitable for inter-laboratory comparison of C. parvum subtypes. As the majority of genotypes (79%) were unique among epidemiologically unrelated samples, there was efficiency to infer linkage, and epidemiological concordance was observed in historical outbreaks. We propose that the multilocus variable number of tandem repeats analysis scheme is suitable to assist outbreak investigations.

A scoping review of risk factors and transmission routes associated with human giardiasis outbreaks in high-income settings.

The flagellated pathogen Giardia duodenalis is one of the leading causes of parasitic gastrointestinal illness worldwide. In many higher income countries, such as the United Kingdom, the disease is often perceived as being travel-related, likely leading to the under-reporting of sporadic cases and outbreaks. A summary of the literature describing outbreaks and risk factors in higher income countries is necessary to improve our understanding of this pathogen and identify existing knowledge gaps. Initial literature searches were carried out in September 2016 and updated at regular intervals until November 2021, using appropriate search terms in Medline, Embase and PubMed databases. A total of 75 papers met the inclusion criteria, revealing that the consumption of contaminated water and contact with young children of diaper-wearing age were the most common transmission routes leading to outbreaks of giardiasis. Of the ten studies where food was primarily associated with outbreaks, food handlers accounted for eight of these. Another reported transmission route was direct contact with fecal material, which was reported in six studies as the primary transmission route. Travel-associated giardiasis was considered the sole transmission route in two studies, whereas multiple transmission routes contributed to giardiasis outbreaks in eleven studies. The evidence around zoonotic transmission was less clear and hampered by the lack of robust and regularly applied parasite molecular typing techniques. This literature review summarizes the findings of Giardia outbreak investigations and epidemiological studies in high-income countries. Transmission routes are identified and discussed to highlight the associated risk factors. These data also indicate gaps in our current knowledge that include the need for robust, in-depth molecular studies and have underscored the importance of water as a transmission route for Giardia cysts. These future molecular studies will improve our understanding of Giardia epidemiology and transmission pathways in higher income countries to prevent spread of this significantly under-reported pathogen.

The first UK report of a rare Cryptosporidium hominis genetic variant isolated during a complex Scottish swimming pool outbreak.

Cryptosporidium species are responsible for causing the majority of parasite-related gastrointestinal infections in the UK. This report describes an outbreak of 12 laboratory-confirmed cryptosporidiosis cases identified as part of a Scottish swimming pool investigation, with 9 primary and 3 secondary cases occurring over an 8-week period. Molecular speciation was successful for 11/12 cases, which revealed 10 Cryptosporidium hominis cases and 1 Cryptosporidium parvum case. Of the 10 C. hominis cases, further typing identified 7 as being an unusual sub-type, IbA6G3, which is the first description in the UK of this rare variant. The remaining three C. hominis cases were identified as the common IbA10G2 subtype. Following implementation of control measures on two occasions, no further cases were reported. This report highlights the importance of molecular typing to identify and characterize outbreaks, and emphasizes the need to adhere to swimming pool guidance. It also raises awareness of the potential for outbreaks to involve multiple species/sub-types, and emphasizes the importance of strong public health leadership to ensure effective multi-agency investigations and management of outbreaks.

Molecular Epidemiology of Giardia Infections in the Genomic Era.

Giardia duodenalis is a major gastrointestinal parasite of humans and animals across the globe. It is also of interest from an evolutionary perspective as it possesses many features that are unique among the eukaryotes, including its distinctive binucleate cell structure. While genomic analysis of a small number of isolates has provided valuable insights, efforts to understand the epidemiology of the disease and the population biology of the parasite have been limited by the molecular tools currently available. We review these tools and assess the impact of affordable and rapid genome sequencing systems increasingly being deployed in diagnostic settings. While these technologies have direct implications for public and veterinary health, they will also improve our understanding of the unique biology of this fascinating parasite.

A descriptive case of persistent Acanthamoeba keratitis: raising awareness of this complex ocular disease.

BACKGROUND: Acanthamoeba species are ubiquitous free-living organisms found in the environment. They can cause a sight-threatening disease of the cornea termed Acanthamoeba keratitis (AK), often associated with contact-lens wearers. This case review describes a persistent presentation of AK and raises awareness of the challenges faced when diagnosing and managing the disease. It highlights the importance of an accurate and rapid diagnosis to assist patient management and to maximize the potential for a better outcome. CASE PRESENTATION: A 73-year-old female was admitted to hospital due to vision impairment of her left eye. Following a clinical examination, the diagnosis of herpes simplex keratitis (HSK) was reported and treated with antivirals. However, deterioration of her keratitis continued after initial treatment, which prompted an investigation into the possibility of AK. Molecular testing of sequential corneal tissue was performed using a real-time PCR assay alongside further clinical examinations. Acanthamoeba species DNA was isolated from seven out of eight corneal tissues over a 12 month period. Following prolonged drug treatment and two corneal transplants, the individual's symptoms ceased and further molecular testing of corneal tissue was negative. CONCLUSIONS: Acanthamoeba keratitis can be easily misdiagnosed due to the similarities in the clinical presentation to other, much more common ocular pathogens. This case highlights the importance of considering AK in the first-line diagnosis, and raises awareness that an early, accurate and rapid diagnosis is crucial to improve patient outcome.

An update on the incidence of human giardiasis in Scotland, 2011-2018.

BACKGROUND: Giardia duodenalis is one of the most common parasites in the UK to cause diarrhoeal illness. Giardiasis is likely to be significantly under-reported in the UK as laboratory testing is largely based on examining stool samples from individuals with a recent travel history. This results in the majority of locally-acquired cases going undetected. To increase awareness of giardiasis, we describe data gathered from cases reported within Scotland during 2011-2018. METHODS: All of the 21 Scottish National Health Service (NHS) diagnostic microbiology laboratories performed microscopy examination to detect Giardia cysts in stools, from mostly travel-related cases. The exception was one laboratory that implemented an antigen-based enzyme immunoassay in 2015. This resulted in every submitted stool being tested for Giardia. Laboratory-confirmed cases of giardiasis were reported to Health Protection Scotland (HPS) via the Electronic Communication of Surveillance in Scotland (ECOSS) during the eight-year period. Data for calculating the incidence per 100,000 of the population were obtained from the National Records of Scotland mid-2018 population estimates in Scotland. RESULTS: A total of 1631 Scottish cases were reported during 2011-2018 (8-year mean: 204; range: 166-269). National Health Service Grampian, Borders and Lothian reported the highest incidence of Giardia (9.8, 7.5 and 6.7 per 100,000, respectively), all of which were above the Scottish mean incidence (3.8 per 100,000). Following the implementation of antigen testing in NHS Grampian during 2015, reports significantly increased 3.6-fold (P = 0.005). The highest incidence of giardiasis occurred in the 20-49 years age group (mean 5.4 per 100,000). Of interest, the mean incidence of giardiasis was significantly higher in males than in females (4.8 versus 3.1 per 100,000, respectively; P < 0.0001). CONCLUSIONS: This report highlights the need to capture enhanced information on every laboratory-confirmed case of giardiasis to gain a better understanding of the local sources and transmission pathways occurring in Scotland. In addition, implementing sensitive, automated technologies across UK NHS diagnostic microbiology laboratories to permit the efficient, routine testing of every submitted stool for Giardia, should be encouraged to ensure all cases are identified and treated appropriately.

Schistosomiasis in a Scottish school group after freshwater swimming in Uganda: the need to raise awareness.

INTRODUCTION: Schistosomiasis, a travel-related trematode infection, can cause a range of symptoms with potentially life-threatening complications. In this report, we describe an outbreak of schistosomiasis in a Scottish school group that had travelled to Uganda. We discuss the requirement for robust and accurate pre-travel advice, and the importance of raising awareness in travellers, particularly due to the asymptomatic nature of the disease. In addition, we highlight the need to submit a serum sample for laboratory testing on return from endemic regions where freshwater exposure has occurred. CASE PRESENTATION: A Scottish school group consisting of 19 individuals visited Uganda during July 2016 with one positive symptomatic case identified on return to the UK. As three of the individuals were not Scottish residents, their data were excluded from this report. Freshwater exposure was noted from taking part in activities which included swimming in the Nile. The Scottish Parasite Diagnostic and Reference Laboratory performed serology testing using sera from 16 Scottish residents to detect IgG towards Schistosoma egg antigens. Thirteen were positive despite only one case being symptomatic. CONCLUSION: The high positivity rate raised several issues. These included the lack of a robust risk assessment by the travel company organizing the trip, the lack of awareness of schistosomiasis by some individuals, the lack of appropriate and accurate pre-travel advice, and the asymptomatic nature of the infection. This report provides supportive evidence to strengthen the need for improvements to prevent largely asymptomatic cases being missed in future.

Schistosomiasis in Scottish travellers: public health importance of laboratory testing and the need for enhanced surveillance.

Background: Imported schistosomiasis is of significant public health importance and is likely to be underestimated since infection is often asymptomatic. We describe data from travellers residing in Scotland which includes a subset of group travellers from one of the largest Health Boards in Scotland. Methods: Clotted bloods were obtained during the period 2001-15 from a total of 8163 Scottish travellers. This included seven groups comprising of 182 travellers. Sera were examined for the presence of Schistosome species antibody at the Scottish Parasite Diagnostic and Reference Laboratory (SPDRL). Results: Of all, 25% (n = 1623) tested positive with 40% (n = 651) of those patients aged between 20 and 24 years. Although 62% (n = 1006) of those who tested positive reported travel to Africa, important information on the specific region visited was lacking in almost one-third of samples received. Overall, 62 (34%) of group travellers tested positive and 95% (n = 59) reporting travel to Africa. Conclusions: Globalization, affordable air travel and improved awareness, are likely to contribute towards the increasing number of imported schistosomiasis cases. Therefore, enhanced surveillance capturing detailed travel history and fresh water exposures will improve risk stratification, pre-travel advice and optimize testing and treatment regimes for this increasingly important parasitic disease.

Comparison of In Vivo Confocal Microscopy, PCR and Culture of Corneal Scrapes in the Diagnosis of Acanthamoeba Keratitis.

PURPOSE: Acanthamoeba keratitis (AK) is an uncommon but serious corneal infection, in which delayed diagnosis carries a poor prognosis. Conventional culture requires a long incubation period and has low sensitivity. Polymerase chain reaction (PCR) and in vivo confocal microscopy (IVCM) are available alternative diagnostic modalities that have increasing clinical utility. This study compares confocal microscopy, PCR, and corneal scrape culture in the early diagnosis of AK. METHODS: We reviewed the case notes of patients with a differential diagnosis of AK between June 2016 and February 2017 at the Bristol Eye Hospital, United Kingdom. Clinical features at presentation, and results of IVCM, PCR, and corneal scrape cultures were analyzed. RESULTS: A total of 25 case records were reviewed. AK was diagnosed in 14 patients (15 eyes). Based on the definition of "definite AK," the diagnostic sensitivities of IVCM, PCR, and corneal scrape cultures were 100% [95% confidence interval (CI), 63.1%-100%], 71.4% (95% CI, 41.9%-91.6%) and 33.3% (95% CI, 9.9%-65.1%), respectively. The 3 methods showed a specificity of 100% and a positive predictive value of 100%. Using a reference standard of only positive corneal cultures, IVCM, and PCR had a sensitivity of 100% (95% CI, 29.2%-100%) and 75% (95% CI, 19.4%-99.4%), respectively. CONCLUSIONS: All 3 diagnostic tests are highly specific, and a positive test result is highly predictive of disease presence. IVCM is both highly sensitive and specific when performed by an experienced operator. PCR is a useful adjunct in the diagnosis of AK because of its wider availability compared with IVCM, and it may be used in combination with IVCM for microbiologic confirmation.

Cyclosporiasis in travellers returning to the United Kingdom from Mexico in 2017: lessons from the recent past to inform the future.

During the summers of 2015 and 2016, the United Kingdom experienced large outbreaks of cyclosporiasis in travellers returning from Mexico. As the source of the outbreaks was not identified, there is the potential for a similar outbreak to occur in 2017; indeed 78 cases had already been reported as at 27 July 2017. Early communication and international collaboration is essential to provide a better understanding of the source and extent of this recurring situation.

The prevalence and genotypic analysis of Toxoplasma gondii from individuals in Scotland, 2006-2012.

BACKGROUND: Contemporary information relating to the prevalence of Toxoplasma gondii in humans is lacking for the UK population, with even less information available about the human prevalence of the parasite in Scotland. To address this, two different study groups were used to determine the prevalence and genotypes of Toxoplasma gondii in the Scottish population. METHODS: The first study group included serum samples from blood donors (n = 3273) over a four-year period (2006-2009) and the second study group comprised of DNA samples extracted from human brains (n = 151) over a five-year period (2008-2012). A T. gondii IgG ELISA was performed to determine seroprevalence and available sera from individuals who had seroconverted were tested by TgERP ELISA (sporozoite specific antigen). Human brain DNA was tested for T. gondii by ITS1 PCR and positives genotyped at the SAG3 and GRA6 loci by PCR-RFLP analysis. RESULTS: Seroprevalence to T. gondii from blood donors was found to be 13.2 % (95 % CI: 11.5-15.1 %). Evidence of seroconversion (n = 2) as well as reversion to sero-negative status (n = 6) was evident from blood donors who had donated within all four collection periods (n = 184). The TgERP ELISA (indicating oocyst infection) was positive for one individual. The molecular detection of T. gondii DNA from human brains indicated a prevalence of 17.9 % (95 % CI: 12.1-24.9 %), with genotyping identifying alleles for types I and III. An increase in age was associated with an increase in detection of the parasite within both study groups. CONCLUSIONS: Our research provides current figures for the prevalence of T. gondii in Scotland and also shows evidence of seroreversion within the cohort of blood donors. In both study groups there was a correlation between increasing age and an increase in T. gondii prevalence, indicating that acquired infection plays an important role within the Scottish population.

An unusual case of vaginal myiasis.

INTRODUCTION: Myiasis, a term used to describe the infestation of a live animal by fly larvae, is rarely reported in human subjects. The adult fly lays its eggs on living tissue that progresses to become larvae that feed on living tissue having gone through three developmental stages known as the first, second and third instar. The larvae become pupae before finally developing into adults. CASE PRESENTATION: We describe an unusual case of a 79-year-old female who collapsed in her garden and lay there for several days before presenting to her local hospital Accident and Emergency department with an infestation of larvae in her vagina labia, identified as those from the Protophormia species northern blowfly. After complete removal of the larvae using tweezers followed by cleansing of the affected area and a course of antibiotics, the patient's condition improved. A follow-up review by the local gynaecology team revealed no evidence of further infestation. CONCLUSION: It is our understanding that this is the first highly unusual case of a blowfly larvae infestation to be reported in a human within the UK.

A Scottish multi-centre service evaluation examining the prevalence and diagnosis of Trichomonas vaginalis in symptomatic women attending sexual health clinics.

Trichomoniasis caused by the protozoan parasite Trichomonas vaginalis (TV) is one of the most commonly occurring sexually transmitted infections of non-viral origin. This study examines the prevalence of TV infection amongst consenting symptomatic women attending three of the largest sexual health clinics in Scotland, United Kingdom. In addition, an evaluation of three testing methods to identify TV from vaginal fluid was performed involving the commercial Hologic APTIMA TV transcription-mediated amplification assay, a real-time PCR assay and microscopy. A total of 398 patients consented to participation and all were tested by the three methods. The prevalence of TV was 2.8% (n = 11), with both molecular assays correctly detecting an additional two cases of TV compared to microscopy. The prevalence of three other sexually transmitted pathogens, namely Chlamydia trachomatis, Neisseria gonorrhoeae and herpes simplex virus were 7.3% (n = 31), 0.3% (n = 1) and 1.5% (n = 6), respectively. The majority of TV cases (78%; n = 8) occurred in women greater than 29 years of age compared to most Chlamydia trachomatis cases, who were aged 30 or less (97%; n = 30).

Cyclospora infection linked to travel to Mexico, June to September 2015.

Cyclospora cayetanensis was identified in 176 returned travellers from the Riviera Maya region of Mexico between 1 June and 22 September 2015; 79 in the United Kingdom (UK) and 97 in Canada. UK cases completed a food exposure questionnaire. This increase in reported Cyclospora cases highlights risks of gastrointestinal infections through travelling, limitations in Cyclospora surveillance and the need for improved hygiene in the production of food consumed in holiday resorts.

An Outbreak of Cryptosporidium parvum across England & Scotland Associated with Consumption of Fresh Pre-Cut Salad Leaves, May 2012.

BACKGROUND: We report a widespread foodborne outbreak of Cryptosporidium parvum in England and Scotland in May 2012. Cases were more common in female adults, and had no history of foreign travel. Over 300 excess cases were identified during the period of the outbreak. Speciation and microbiological typing revealed the outbreak strain to be C. parvum gp60 subtype IIaA15G2R1. METHODS: Hypothesis generation questionnaires were administered and an unmatched case control study was undertaken to test the hypotheses raised. Cases and controls were interviewed by telephone. Controls were selected using sequential digit dialling. Information was gathered on demographics, foods consumed and retailers where foods were purchased. RESULTS: Seventy-four laboratory confirmed cases and 74 controls were included in analyses. Infection was found to be strongly associated with the consumption of pre-cut mixed salad leaves sold by a single retailer. This is the largest documented outbreak of cryptosporidiosis attributed to a food vehicle.

Plasmodium knowlesi: clinical presentation and laboratory diagnosis of the first human case in a Scottish traveler.

The first imported case of Plasmodium knowlesi in Scotland is described in a 33-year-old female with a travel history to Borneo. The patient ceased to take antimalarial prophylaxis after 4 days of her 10-day visit and presented with a history of fever, rigor, vomiting, and diarrhea after 13 days on her return to the UK. Malaria antigen detection using the Optimal-IT and Binax-NOW kits was negative. Unusual trophozoite-like structures were observed under microscopic examination and the identification of P. knowlesi performed by a nested polymerase chain reaction (PCR) gel-based approach was confirmed by using a PCR-sequencing assay.

The rapid detection of Cryptosporidium and Giardia species in clinical stools using the Quik Chek immunoassay.

Diagnostic testing in the United Kingdom for Cryptosporidium and Giardia species is routinely performed by microscopy. In this study, two hundred stool samples from human clinical cases were examined for the presence of these two parasites comparing microscopy with an antigen immunoassay, Quik Chek (Techlab, Inc.). The Quik Chek assay was shown to have a sensitivity and specificity for Cryptosporidium detection of 87.6% and 98.9% respectively and for Giardia detection, 93.3% and 99.4% respectively. The high correlation with microscopy data provides evidence to support implementation of this rapid test within diagnostic microbiology laboratories.