Absence of Leishmania spp. DNA in road-killed wild mammals in Southern Brazil.

Leishmaniasis are neglected diseases transmitted by vectors that affect domestic and wild animals, including humans. Due to its incidence and lethality, this zoonosis is a worrying public health problem, making it essential to identify all links in the transmission chain. Infection of wild mammals by Leishmania spp. remains poorly understood, especially in southern Brazil. Therefore, the objective was to research, using the PCR technique, the presence of Leishmania spp. DNA in road-killed wild mammals in Southern Brazil. Carcasses of 96 animals were collected from highways in the Pelotas microregion, Rio Grande do Sul, southern Brazil and subjected to necropsies. Tissue fragments (spleen, skin, liver, kidney, heart, lung, lymph nodes, bone marrow and blood) were collected and genomic DNA was extracted. PCR protocols targeting the ITS1, kDNA and 18S genes were tested. We found no evidence of Leishmania spp. circulation in the studied population. However, epidemiological studies like this one are of great relevance, as they allow monitoring of the occurrence of pathogens and help identify possible risk areas. As these animals act as epidemiological markers for the presence of the microorganism, studies must be carried out continuously to understand whether there are sources of infection in the region.

No evidence of pathogenicity of Dientamoeba fragilis following detection in stools: A case-control study.

Dientamoeba fragilis is a ubiquitous intestinal parasite with detection in the stools that has become increasingly frequent following the advent of PCR as a routine screening tool. However, the pathogenicity of this parasite is still much debated. In order to assess the potentially pathogenic nature of this protozoan, a retrospective case-control study was carried out between January and December 2020 on patients from Toulouse University Hospital, with the aim of evaluating the potential clinical effects and changes in laboratory parameters linked to the presence and load of D. fragilis in stools. After matching age, sex and mode of care (consultation or hospitalisation), no significant difference was observed in the frequency of clinical signs between the 36 patients who tested positive for Dientamoeba fragilis PCR in their stools and the 72 control patients who were PCR negative for this protozoan. The presence of D. fragilis in the faeces was not associated with changes in laboratory parameters. Furthermore, a high digestive load of D. fragilis had no identifiable impact on clinical and laboratory parameters. Only the concomitant presence of Blastocystis sp. in stools was significantly more frequent in the D. fragilis group (uni- and multivariate analysis). Finally, this study showed no significant difference in clinical or laboratory signs between patients carrying Dientamoeba fragilis and the control group, regardless of the intestinal parasite load, suggesting that D. fragilis could be considered a commensal of the digestive tract.

Title: Aucune preuve de la pathogénicité de Dientamoeba fragilis détecté dans les selles : une étude cas-témoins. Abstract: Dientamoeba fragilis est un parasite digestif ubiquitaire dont la détection dans les selles est devenue de plus en plus fréquente avec l'avènement de la PCR comme outil de détection de routine. Cependant, la pathogénicité de ce parasite est encore très discutée. Afin d'évaluer le caractère potentiellement pathogène de ce protozoaire, une étude rétrospective cas-témoins a été réalisée entre janvier et décembre 2020 sur des patients du CHU de Toulouse, dans le but d'évaluer les effets cliniques et biologiques potentiels associés à la présence et à la charge de D. fragilis dans les selles. Après appariement sur l'âge, le sexe et le mode de prise en charge (consultation ou hospitalisation), aucune différence significative n'a été observée dans la fréquence des signes cliniques entre les 36 patients testés positifs pour la PCR de Dientamoeba fragilis dans les selles et les 72 patients témoins avec une PCR négative pour ce protozoaire. La présence de D. fragilis dans les selles n'était pas associée à des modifications des paramètres biologiques. De plus, une charge digestive élevée de D. fragilis n'avait pas d'impact identifiable sur les paramètres cliniques et biologiques. Seule la présence concomitante de Blastocystis sp. dans les selles était significativement plus fréquente dans le groupe D. fragilis (analyse uni- et multivariée). En conclusion, cette étude n'a pas montré de différence significative concernant les signes cliniques ou biologiques entre les patients porteurs de Dientamoeba fragilis et le groupe témoin, quelle que soit la charge parasitaire digestive, indiquant que D. fragilis pourrait être considéré comme un commensal du tube digestif.

Reliable and specific detection of Acanthamoeba spp. in dishcloths using quantitative real-time PCR assay.

Acanthamoeba spp., are ubiquitous protist which belongs to Free-Living Amoeba (FLA) group, is considered as causal agent of side-threatening keratitis or fatal encephalitis among other human infections. Besides, this parasite has been reported as host for other microorganisms important to human health such as Campylobacter spp. or Vibrio spp. among others. This role of Acanthamoeba as pathogen and environmental phagocyte has increased the reports confirming its presence in human related environments, acting as a water quality indicator. Considering the tide relationship between water and kitchen environments, and the high prevalence of Acanthamoeba in water sources, the present study aims to establish a quick and accurate protocol based on DNA extraction and a real time qPCR assay to detect Acanthamoeba spp. in dishcloths. The procedure has been validated by processing 17 used dishcloths. Our findings demonstrated the high sensitivity of the qPCR assay used which was capable of detecting up to one Acanthamoeba from an in vitro contaminated dishcloth. The protocol accurately detected 64.7% of positive samples for Acanthamoeba spp, (in 4 samples DNA concentrations corresponded to 1-102 amoebae). Our findings demonstrate the importance of FLA surveillance by efficient and sensitive methods since one amoeba is capable of colonizing human related food environments such as kitchens sinks and could be a potential source of infection.

Morphological and molecular identification of Sarcocystis falcatula from the emerald toucanet (Aulacorhynchus albivitta) in Colombia.

Sarcocystis spp. are cyst-forming coccidia characterized by a two-host predator-prey life cycle. Sarcocysts are formed in muscles or nervous system of the intermediate host, while sporocysts develop in the small intestine of the definitive host. The intermediate hosts of Sarcocystis falcatula are wild birds. Colombia is one of the countries with the greatest biodiversity of birds, however, there are few studies related to this parasite in wild birds. This study presents the morphological and molecular detection of Sarcocystis falcatula collected from the emerald toucanet (Aulacorhynchus albivitta), a wild bird species endemic to South America. Pectoral muscle samples were obtained, and microscopic and molecular detection was performed by light microscopy, transmission electron microscopy, and amplifying of the first internal transcribed spacer (ITS-1) and surface antigen-encoding genes (SAGs). Sarcocystis measured an average of 161  × 42 µm, with a cyst wall ∼0.4 µm thick. Ultrastructurally, the sarcocyst wall type 11b-like consisted of numerous villar protrusions of 850 nm wide on average. The ITS-1 sequence showed 97.0-99.7% identity to S. falcatula previously described from birds in the United States and Brazil, respectively. Concatenated phylogenetic analysis based on SAG2, SAG3 and SAG4 confirmed that the new isolate is grouped with other sequences of Sarcocystis from South America, but divergent from those isolates obtained in North America. The results of this study demonstrate for the first time the presence of S. falcatula in a wild bird from Colombia.

Evaluation of molecular-based methods for the detection and quantification of Cryptosporidium spp. in wastewater.

Cryptosporidium poses significant public health risks as a cause of waterborne disease worldwide. Clinical surveillance of cryptosporidiosis is largely underreported due to the asymptomatic and mildly symptomatic infections, clinical misdiagnoses, and barriers to access testing. Wastewater surveillance overcomes these limitations and could serve as an effective tool for identifying cryptosporidiosis at the population level. Despite its potential, the lack of standardized wastewater surveillance methods for Cryptosporidium spp. challenges implementation design and the comparability between studies. Thus, this study compared and contrasted Cryptosporidium wastewater surveillance methods for concentrating wastewater oocysts, extracting oocyst DNA, and detecting Cryptosporidium genetic markers. The evaluated concentration methods included electronegative membrane filtration, Envirocheck HV capsule filtration, centrifugation, and Nanotrap Microbiome Particles, with and without additional immunomagnetic separation purification (except for the Nanotrap Microbiome Particles). Oocyst DNA extraction by either the DNeasy Powersoil Pro kit and the QIAamp DNA Mini kit were evaluated and the impact of bead beating and freeze-thaw pretreatments on DNA recoveries was assessed. Genetic detection via qPCR assays targeting either the Cryptosporidium 18S rRNA gene or the Cryptosporidium oocyst wall protein gene were tested. Oocyst recovery percentages were highest for centrifugation (39-77 %), followed by the Nanotrap Microbiome Particles (24 %), electronegative filtration with a PBST elution (22 %), and Envirocheck HV capsule filtration (13 %). Immunomagnetic separation purification was found to be unsuitable due to interference from the wastewater matrix. Bead-beating pretreatment enhanced DNA recoveries from both the DNeasy Powersoil Pro kit (314 gc/µL DNA) and the QIAamp DNA Mini kit (238 gc/µL DNA). In contrast, freeze-thaw pretreatment reduced DNA recoveries to under 92 gc/µL DNA, likely through DNA degradation. Finally, while both qPCR assays were specific to Cryptosporidium spp., the 18S rRNA assay had a 5-fold lower detection limit and could detect a wider range of Cryptosporidium spp. than the Cryptosporidium oocyst wall protein assay.

Molecular detection of Toxoplasma gondii in domestic and wild guinea pigs (Cavia spp.) from the Marangani district in Cuzco, Peru.

Toxoplasmosis is a foodborne disease caused by the protozoan Toxoplasma gondii, and transmitted to humans by eating raw or undercooked meat, mainly. Poultry, beef, and pork are the main meats consumed in Peru; despite this, guinea pig meat is also widely consumed. For this reason, the objective of this study was to molecularly detect T. gondii in domestic and wild guinea pigs from the Marangani district in Cuzco, Peru, and identify some risk factors associated with this pathogen. DNA was extracted from the brain tissue samples of guinea pigs (30 domestic and 30 wild), and PCR protocols were used to amplify the internal transcribed spacer (ITS-1) region and a 529 bp fragment from the T. gondii genome. T. gondii DNA was detected in 14 (23.3%) guinea pigs. T. gondii frequency was 33.3% in domestic guinea pigs and 13.3% in wild guinea pigs. Our results demonstrated that guinea pigs represent an important source for T. gondii infection in human populations in this locality.

Challenging diagnosis of Plasmodium ovale malaria in a Colombian traveler: the importance of including P. ovale wallikeri in molecular screening.

This study reports a challenging diagnosis of Plasmodium ovale malaria in a Colombian citizen returning from Cameroon. Initial microscopy screenings conducted at two private hospitals yielded conflicting results, with the first showing negative smears and the second diagnosing P. vivax. Subsequent microscopy examinations at two government laboratories identified P. ovale, although the routine species-specific PCR strategy was negative. PCR confirmation was finally obtained when P. ovale wallikeri primers were used. Although P. ovale is not frequently found in Colombia, there is a clear need to include both P. ovale curtisi and P. ovale wallikeri in the molecular diagnostic strategy. Such need stems primarily from their extended latency period, which affects travelers, the increasing number of African migrants, and the importance of accurately mapping the distribution of Plasmodium species in Colombia.

Atypical acquired toxoplasmosis.

A 33-year-old male presented with unilateral painless vision loss with a history of sub-tenon steroid for the same. The fundus showed an elevated focus of retinochoroiditis with vitritis. On investigating for the cause, polymerase chain reaction test on the anterior chamber tap was found to be positive for Toxoplasma. Such confusing and atypical cases usually produce a clinical dilemma and should be managed in a stepwise manner. Ancillary investigations usually provide a clue to the clinician and should be performed without any hesitation.

The prevalence and genotypes of Cryptosporidium spp. in bar-headed goose (Anser indicus) in China.

Cryptosporidium spp. is an important foodborne and waterborne pathogen in humans and animals, causing diarrhoea in humans and respiratory and gastrointestinal diseases in birds. However, reports of Cryptosporidium infection in bar-headed goose are limited. To determine the infection rate and species/genotypes of Cryptosporidium in bar-headed goose in China, a total of 358 fecal samples were collected from 3 regions. Nested PCR was used to amplify Cryptosporidium SSU rRNA regions from the fecal extracted-DNA samples. The total infection rate of Cryptosporidium in bar-headed in China was 3.9 % (14/358), with 4.2 % (5/120) in Aba (Ngawa) Tibetan and Qiang Autonomous Prefect, Sichuan province, 7.6 % (9/119) in Maqu county, Gansu province, and 0.0 % (0/119) in Caohai, Wei ning county, Guizhou province. The differences in prevalence rate by region were statistically significant. All positive samples were identified as Cryptosporidium goose genotype I (n = 14). This is the first systematic investigation of the epidemiological status and dominant species/genotypes of Cryptosporidium in bar-headed goose in China, thereby enhancing our understanding of the epidemiology of Cryptosporidium infection in wild migratory birds.

Molecular detection of Toxoplasma gondii and Neospora caninum in seabirds collected along the coast of Santa Catarina, Brazil.

Toxoplasma gondii and Neospora caninum are two closely related protozoans that infect a wide range of animals, including birds. However, the occurrence of N. caninum and T. gondii in seabirds is unknown. Therefore, this study aimed to determine the presence of T. gondii and N. caninum DNA in tissue samples of seabirds. Tissue samples of the pectoral muscles, heart, and brain were collected from 47 birds along the coastline of Santa Catarina State, SC, Brazil. The DNA was extracted from the tissues and screened using nested-PCR (nPCR) targeting internal transcribed spacer 1 (ITS1). T. gondii DNA was detected in tissues from seven seabirds (7/47, 14.8%), kelp gull (Larus dominicanus) (5/21), and Manx shearwater (Puffinus puffinus) (2/8). N. caninum DNA was detected in tissues of nine seabirds (9/47, 19.1%), the kelp gull (L. dominicanus) (4/21), Manx shearwater (P. puffinus) (2/8), neotropic cormorant (Phalacrocorax brasilianus) (1/4), brown booby (Sula leucogaster) (1/5), and white-chinned petrel (Procellaria aequinoctialis) (1/1); however, no co-infection was observed. In conclusion, this study showed the circulation of N. caninum and T. gondii in seabirds along the coastline of Santa Catarina State. Further studies are required to clarify the role of these birds in the epidemiology of neosporosis and toxoplasmosis.

Ultrasensitive malaria detection system for Anopheles mosquito field surveillance using droplet digital PCR.

Malaria remains a significant global public health concern, with a recent increase in the number of zoonotic malaria cases in Southeast Asian countries. However, limited reports on the vector for zoonotic malaria exist owing to difficulties in detecting parasite DNA in Anopheles mosquito vectors. Herein, we demonstrate for the first time that several Anopheles mosquitoes contain simian malaria parasite DNA using droplet digital PCR (ddPCR), a highly sensitive PCR method. An entomological survey was conducted to identify simian malaria vector species at Phra Phothisat Temple (PPT), central Thailand, recognized for a high prevalence of simian malaria in wild cynomolgus macaques. A total of 152 mosquitoes from six anopheline species were collected and first analyzed by a standard 18S rRNA nested-PCR analysis for malaria parasite which yielded negative results in all collected mosquitoes. Later, ddPCR was used and could detect simian malaria parasite DNA, i.e. Plasmodium cynomolgi, in 25 collected mosquitoes. And this is the first report of simian malaria parasite DNA detection in Anopheles sawadwongporni. This finding proves that ddPCR is a powerful tool for detecting simian malarial parasite DNA in Anopheles mosquitoes and can expand our understanding of the zoonotic potential of malaria transmission between monkeys and humans.

Multicenter evaluation of the Toxoplasma gondii Real-TM (Sacace) kit performance for the molecular diagnosis of toxoplasmosis.

The molecular detection of Toxoplasma gondii DNA is a key tool for the diagnosis of disseminated and congenital toxoplasmosis. This multicentric study from the Molecular Biology Pole of the French National Reference Center for toxoplasmosis aimed to evaluate Toxoplasma gondii Real-TM PCR kit (Sacace). The study compared the analytical and clinical performances of this PCR assay with the reference PCRs used in proficient laboratories. PCR efficiencies varied from 90% to 112%; linearity zone extended over four log units (R2 > 0.99) and limit of detection varied from 0.01 to ≤1 Tg/mL depending on the center. Determined on 173 cryopreserved DNAs from a large range of clinical specimens, clinical sensitivity was 100% [106/106; 95 confidence interval (CI): 96.5%-100%] and specificity was 100% (67/67; 95 CI: 94.6%-100%). The study revealed two potential limitations of the Sacace PCR assay: the first was the inconsistency of the internal control (IC) when added to the PCR mixture. This point was not found under routine conditions when the IC was added during the extraction step. The second is a lack of practicality, as the mixture is distributed over several vials, requiring numerous pipetting operations. Overall, this study provides useful information for the molecular diagnosis of toxoplasmosis; the analytical and clinical performances of the Sacace PCR kit were satisfactory, the kit having sensitivity and specificity similar to those of expert center methods and being able to detect low parasite loads, at levels where multiplicative analysis gives inconsistently positive results. Finally, the study recommends multiplicative analysis in particular for amniotic fluids, aqueous humor, and other single specimens.

Development of nucleic acid lateral flow immunoassay for molecular detection of Entamoeba moshkovskii and Entamoeba dispar in stool samples.

Entamoeba moshkovskii, recently known as a possible pathogenic amoeba, and the non-pathogenic Entamoeba dispar are morphologically indistinguishable by microscopy. Although PCR was used for differential diagnosis, gel electrophoresis is labor-intensive, time-consuming, and exposed to hazardous elements. In this study, nucleic acid lateral flow immunoassay (NALFIA) was developed to detect E. moshkovskii and E. dispar by post-PCR amplicon analysis. E. moshkovskii primers were labeled with digoxigenin and biotin whereas primers of E. dispar were lebeled with FITC and digoxigenin. The gold nanoparticles were labeled with antibodies corresponding to particular labeling. Based on the established assay, NALFIA could detect as low as 975 fg of E. moshkovskii target DNA (982 parasites or 196 parasites/microliter), and 487.5 fg of E. dispar target DNA (444 parasites or 89 parasites/microliter) without cross-reactivity to other tested intestinal organisms. After testing 91 stool samples, NALFIA was able to detect seven E. moshkovskii (87.5% sensitivity and 100% specificity) and eight E. dispar samples (66.7% sensitivity and 100% specificity) compared to real-time PCR. Interestingly, it detected three mixed infections as real-time PCR. Therefore, it can be a rapid, safe, and effective method for the detection of the emerging pathogens E. moshkovskii and E. dispar in stool samples.

New insight into avian malaria vectors in New Zealand.

BACKGROUND: Mosquitoes (Culicidae) are vectors for most malaria parasites of the Plasmodium species and are required for Plasmodium spp. to complete their life cycle. Despite having 16 species of mosquitoes and the detection of many Plasmodium species in birds, little is known about the role of different mosquito species in the avian malaria life cycle in New Zealand. METHODS: In this study, we used nested polymerase chain reaction (PCR) and real-time PCR to determine Plasmodium spp. prevalence and diversity of mitochondrial cytochrome b gene sequences in wild-caught mosquitoes sampled across ten sites on the North Island of New Zealand during 2012-2014. The mosquitoes were pooled by species and location collected, and the thorax and abdomens were examined separately for Plasmodium spp. DNA. Akaike information criterion (AIC) modeling was used to test whether location, year of sampling, and mosquito species were significant predictors of minimum infection rates (MIR). RESULTS: We collected 788 unengorged mosquitoes of six species, both native and introduced. The most frequently caught mosquito species were the introduced Aedes notoscriptus and the native Culex pervigilans. Plasmodium sp DNA was detected in 37% of matched thorax and abdomen pools. When considered separately, 33% of abdomen and 23% of thorax pools tested positive by nested PCR. The MIR of the positive thorax pools from introduced mosquito species was 1.79% for Ae. notoscriptus and 0% for Cx. quinquefasciatus, while the MIR for the positive thorax pools of native mosquito species was 4.9% for Cx. pervigilans and 0% for Opifex fuscus. For the overall MIR, site and mosquito species were significant predictors of Plasmodium overall MIR. Aedes notoscriptus and Cx. pervigilans were positive for malaria DNA in the thorax samples, indicating that they may play a role as avian malaria vectors. Four different Plasmodium lineages (SYAT05, LINN1, GRW6, and a new lineage of P (Haemamoeba) sp. AENOT11) were identified in the pooled samples. CONCLUSIONS: This is the first detection of avian Plasmodium DNA extracted from thoraxes of native Culex and introduced Aedes mosquito species in New Zealand and therefore the first study providing an indication of potential vectors in this country.

Molecular monitoring of treatment efficacy in human visceral leishmaniasis.

BACKGROUND: Focused efforts of the visceral leishmaniasis elimination program have led to a drastic decline in cases, and the present challenge is disease monitoring, which this study aimed to assess. METHODS: A Leishmania kinetoplastid-targeted qPCR quantified parasite load at disease presentation, and following treatment completion (n=49); an additional 80 cases were monitored after completion of treatment. RESULTS: The parasite load at disease presentation was 13 461.00 (2560.00-37764.00)/µg gDNA, which upon completion of treatment reduced in 47 of 49 cases to 1(1-1)/µg gDNA, p<0.0001. In 80 cases that presented >2 months post-treatment, their parasite burden similarly decreased to 1(1-1)/µg gDNA except in 6 of 80 cases, which were qPCR positive. CONCLUSION: In 129 cases of visceral leishmaniasis, qPCR by quantification of parasite burden proved effective for monitoring treatment.

Phylogenetic analysis of Acanthamoeba isolated from soil samples and nasal cavities of patients with malignancy: a public health concern in the northwest of Iran.

BACKGROUND: The genus Acanthamoeba is reported from various environmental sources and can cause multiple complications, including chronic amoebic aeratitis and amoebic granulomatous encephalitis. This study investigated the presence and genotyping of Acanthamoeba in the soil of parks and patients with malignancies referred to health centers in Zanjan city, Iran. METHODS: In this cross-sectional study, 200 soil samples were collected from amusement parks in Zanjan city from September 2017 to May 2018. Samples were cultured on 1.5% non-nutrient agar, and the Acanthamoeba genus was identified using the morphological method. PCR was performed on all positive environmental samples, and six microscopically positive clinical samples belonged to our previous study. DNA sequencing of 18S rRNA was performed to analyze the genetic pattern of some PCR-positive isolates. RESULTS: Microscopic results showed that 96 (48%) soil samples were positive. PCR confirmed all positive cases of clinical samples and 84 soil samples. Out of the PCR-positive samples, 20 soil samples and five clinical samples were sequenced successfully. All soil isolates belonged to the T4 genotype, and three and two clinical samples belonged to T4 and T5 genotypes, respectively. CONCLUSION: : The presence of Acanthamoeba in both the environment and clinical samples of Zanjan city suggests paying greater attention to the infections caused by it.

Novel diagnostic approach for amoebic liver abscess using cell free (cf) DNA: a prospective study.

BACKGROUND: Amoebic liver abscess (ALA) is commonly seen in tropical countries and diagnosis of ALA relies mainly on non-specific serological and imaging techniques as well as PCR from pus. OBJECTIVE: This study evaluated the potential of using cell free DNA (cfDNA) from serum and urine for diagnosing ALA. METHODS: We prospectively evaluated quantitative PCR (qPCR) for detection of cf DNA in serum and urine sample in all liver abscess patients. The samples were collected from patients reporting to emergency ward of Postgraduate Institute of Medical Education and Research, Chandigarh, India with symptoms suggestive of liver abscess. Real time PCR was done to detect cf DNA in serum and urine by targeting 99-bp unit of small subunit rRNA of Entamoeba histolytica and conventional PCR for pus. RESULTS: A total 113 samples (serum and urine) and 100 pus samples were analysed. A total of 62 ALA patients were confirmed; with maximum 57 patients detected by qPCR for cfDNA in the serum, 55 patients by PCR on pus aspirate and 50 ALA patients by qPCR for cfDNA in urine sample. Therefore, the sensitivity of qPCR for detection of cf DNA in serum was 91.94% and for urine was 80.65%. CONCLUSION: A total of 11.2% of ALA patients were diagnosed only through detection of E. histolytica cf DNA in their serum and urine. Detection of cfDNA from serum, urine of ALA has a potential role in future especially for developing countries as it is a rapid, sensitive and patient friendly diagnostic approach.

High prevalence and diversity of Toxoplasma gondii DNA in feral cat feces from coastal California.

Toxoplasma gondii is a zoonotic parasite that can cause severe morbidity and mortality in warm-blooded animals, including marine mammals such as sea otters. Free-ranging cats can shed environmentally resistant T. gondii oocysts in their feces, which are transported through rain-driven runoff from land to sea. Despite their large population sizes and ability to contribute to environmental oocyst contamination, there are limited studies on T. gondii oocyst shedding by free-ranging cats. We aimed to determine the frequency and genotypes of T. gondii oocysts shed by free-ranging domestic cats in central coastal California and evaluate whether genotypes present in feces are similar to those identified in sea otters that died from fatal toxoplasmosis. We utilized a longitudinal field study of four free-ranging cat colonies to assess oocyst shedding prevalence using microscopy and molecular testing with polymerase chain reaction (PCR). T. gondii DNA was confirmed with primers targeting the ITS1 locus and positive samples were genotyped at the B1 locus. While oocysts were not visualized using microscopy (0/404), we detected T. gondii DNA in 25.9% (94/362) of fecal samples. We genotyped 27 samples at the B1 locus and characterized 13 of these samples at one to three additional loci using multi locus sequence typing (MLST). Parasite DNA detection was significantly higher during the wet season (16.3%, 59/362) compared to the dry season (9.7%; 35/362), suggesting seasonal variation in T. gondii DNA presence in feces. High diversity of T. gondii strains was characterized at the B1 locus, including non-archetypal strains previously associated with sea otter mortalities. Free-ranging cats may thus play an important role in the transmission of virulent T. gondii genotypes that cause morbidity and mortality in marine wildlife. Management of free-ranging cat colonies could reduce environmental contamination with oocysts and subsequent T. gondii infection in endangered marine mammals and people.

Molecular diagnosis of visceral leishmaniasis: a French study comparing a reference PCR method targeting kinetoplast DNA and a commercial kit targeting ribosomal DNA.

IMPORTANCE: PCR revolutionized the direct diagnosis of infectious diseases, especially protozooses, where the infectious load is usually low. Commercial PCR methods are available and offer many advantages, including convenience and batch tracking as part of a quality system. For most parameters, the performance of commercial methods is at least as good as that of finely optimized methods developed in expert laboratories. This comparison work has not been done for the molecular diagnosis of visceral leishmaniasis. Leishmania sp. has a unique organelle, the kinetoplast, which corresponds to the mitochondrial DNA. It is organized into a large number of minicircles, which has made it a target for the development of diagnostic PCR. The quanty Leishmaniae, Clonit kit targeting ribosomal DNA was compared to a widely used laboratory-developed method based on kinetoplast DNA. This reference method gave significantly better results, probably due to the difference in the number of repeats of the PCR targets.

CRISPR/Cas12a combined with RPA for detection of T. gondii in mouse whole blood.

BACKGROUND: Toxoplasma gondii is an opportunistic protozoan that is ubiquitous in humans and animals. It can invade any human organ and cause severe diseases, including toxoplasma ophthalmopathy, meningoencephalitis, and liver necrosis. Porcine toxoplasmosis is prevalent in China. CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) and Cas (CRISPR-Associated Protein) systems are widely used for gene editing and pathogen detection. CRISPR-based diagnostics are molecular assays that have been developed to detect parasites with high sensitivity and specificity. METHODS: This study aimed to establish a combined CRISPR/Cas12a and RPA rapid detection method for T. gondii by targeting the B1 gene and 529 bp repeat element (529 RE). The detection results could be visualized by the fluorescence or lateral flow strips (LFS). The sensitivity and specificity of the method were evaluated, and T. gondii-infected mouse blood was used for detection. RESULTS: The results indicated that the established method for T. gondii detection was satisfactory, with a detection limit of 1.5 cp/µl for the two loci. Moreover, the B1 gene could detect 1 tachyzoite per reaction, and the 529 RE could detect 0.1 tachyzoite per reaction, consistently with the highly sensitive nested polymerase chain reaction (PCR) results. The method was suitable for strains, including RH, and did not cross-react with other protozoa DNA with similar habits. The T. gondii-infected mouse blood samples were all positive for T. gondii at 1, 3, and 5 days post infection (dpi). CONCLUSIONS: This study established a rapid, sensitive, and time-saving DNA detection method for T. gondii that has the potential to be an alternative tool for T. gondii detection in the field.