Genotyping of European Toxoplasma gondii strains by a new high-resolution next-generation sequencing-based method

PURPOSE

A new high-resolution next-generation sequencing (NGS)-based method was established to type closely related European type II Toxoplasma gondii strains.

METHODS

T. gondii field isolates were collected from different parts of Europe and assessed by whole genome sequencing (WGS). In comparison to ME49 (a type II reference strain), highly polymorphic regions (HPRs) were identified, showing a considerable number of single nucleotide polymorphisms (SNPs). After confirmation by Sanger sequencing, 18 HPRs were used to design a primer panel for multiplex PCR to establish a multilocus Ion AmpliSeq typing method. Toxoplasma gondii isolates and T. gondii present in clinical samples were typed with the new method. The sensitivity of the method was tested with serially diluted reference DNA samples.

RESULTS

Among type II specimens, the method could differentiate the same number of haplotypes as the reference standard, microsatellite (MS) typing. Passages of the same isolates and specimens originating from abortion outbreaks were identified as identical. In addition, seven different genotypes, two atypical and two recombinant specimens were clearly distinguished from each other by the method. Furthermore, almost all SNPs detected by the Ion AmpliSeq method corresponded to those expected based on WGS. By testing serially diluted DNA samples, the method exhibited a similar analytical sensitivity as MS typing.

CONCLUSION

The new method can distinguish different T. gondii genotypes and detect intra-genotype variability among European type II T. gondii strains. Furthermore, with WGS data additional target regions can be added to the method to potentially increase typing resolution.

Seroepidemiology of toxoplasmosis in pregnant women and detection of infection acquired during pregnancy in Cotonou, Benin

Assessing the prevalence of toxoplasmosis in pregnant women and the associated risk factors is the first step in defining policy for the prevention of congenital toxoplasmosis in a given population. An epidemiological study was conducted during prenatal consultations at the CHU-MEL of Cotonou (Benin) between September 2018 and April 2021 and recruited 549 pregnant women to determine the seroprevalence and potential factors associated with Toxoplasma gondii infection. Toxoplasma gondii IgG/IgM antibodies were detected using an enzyme-linked fluorescence assay (ELFA) technique, an IgG avidity test and an IgG/IgM comparative Western blot to diagnose the maternal toxoplasmosis serological status, the possibility of an infection acquired during pregnancy and congenital infection, respectively. Concomitantly, the participants answered a questionnaire investigating potential risk factors. Toxoplasmosis seroprevalence was estimated at 44.4% (95% CI 40.3-48.6) and the factors significantly associated with T. gondii seropositivity were: age over 30 years, multigravid women and contact with cats. The possibility of an infection acquired during the periconceptional period or the first trimester of pregnancy concerned six women [1.1% (95% CI 0.5-2.0)]. However, due to the low rate of serological controls in seronegative women, a significant proportion of women first tested during the 3rd trimester of pregnancy, and an insufficient sample size, the incidence of primary infection during pregnancy could not be determined. No cases of congenital transmission occurred in the newborns from the suspected cases of primary infection.

Neurocysticercosis Diagnosis in a Non-Endemic Country: France

Diagnosing neurocysticercosis (NCC) is difficult due to its variable clinical presentations and the different imaging techniques used to detect brain damage. This study aimed to evaluate the use of cerebrospinal fluid serology and PCR for diagnosing biological neurocysticercosis in a non-endemic country. We tested samples from patients living in France with suspected NCC and confirmed that 45 of the patients presented with the disease. A total of 89% of patients had previously traveled to countries where the disease was endemic. The sensitivity of Western blots compared to ELISA was not significantly different (80% vs. 60%) (p > 0.05), and neither was the sensitivity of Western blots vs. PCR (78% vs. 56%) (p > 0.05). The PCR sensitivity was 78% and 47% in definitive NCC and in probable NCC. PCR tests using cerebrospinal fluid should be considered as a diagnostic criterion for identifying NCC.

A ring trial to harmonize Toxoplasma gondii microsatellite typing: comparative analysis of results and recommendations for optimization

A ring trial among five European laboratories was organized to reach consistency in microsatellite (MS) typing of the zoonotic parasite Toxoplasma gondii. Three sample sets were circulated and analyzed by each laboratory following a previously published method that is based on fragment length polymorphism of 15 MS markers. The first sample set compared typing results in general and focused on effects of DNA concentration; the second sample set focused on the polymorphic fingerprinting markers that can differentiate T. gondii strains within the same archetypal lineage; and the third set focused on non-archetypal genotypes. Methodological variations between laboratories, including the software programs used to determine MS fragment length, were collated using a questionnaire. Overall, lineage-level typing results reached a high level of agreement, especially in samples with the highest DNA concentrations. However, laboratory-specific differences were observed for particular markers. Major median differences in fragment length, of up to 6 base pairs, were related to the fluorophore used to label fragment-specific primers. In addition, primer pairs with identical sequences obtained from different suppliers resulted in fragments of differing length. Furthermore, differences in the way the sequencing profiles were assessed and interpreted may have led to deviating results in fragment length determination. Harmonization of MS typing, for example, by using the same fluorophores or by numerical adjustments applied to the fragment-lengths determined, could improve the uniformity of the results across laboratories. This is the first interlaboratory comparison, providing guidelines (added as a supplement) for the optimization of this technique.

Seroprevalence and risk factors of Toxoplasma gondii infection in sheep in Algeria

Toxoplasma gondii infection is recognized as one of the major causes of reproductive failure in sheep and goats. This survey was carried out in order to study the seroprevalence of Toxoplasma infection in sheep in Blida, Bouira and Medea regions from Algeria. The sample size was set at 220 animals distributed over 22 farms. Sera were assayed for T. gondii antibody detection by Modified Agglutination Test (MAT). The overall seroprevalence was 35.9% (79/220) with a herd seroprevalence of 77.3% (17/22). The prevalence was significantly higher in Medea (45.7% of 116 sheep), compared to Blida (27.7% of 83 sheep). Bouira region showed the lowest prevalence with 3 positive samples (14.3%) over 21 sheep. Logistic regression analysis revealed that the likelihood of T. gondii infection was higher in semi-extensive sheep breeding, in regions where the presence of cats is strong, and in highlands when compared with semi-intensive sheep breeding, weak presence of cat and in lowland, respectively. This study shows a high seroprevalence of Toxoplasma infection in sheep in these areas.

Toxoplasma gondii infection in sheep from Romania

BACKGROUND

Toxoplasmosis is a widespread zoonosis caused by the intracellular protozoan parasite Toxoplasma gondii. Limited epidemiological information is available about the prevalence of T. gondii in sheep in Romania, and a high incidence would have implications for both the economy and public health. To our knowledge, no studies are available about the T. gondii strains circulating in lambs. The objective of this study was to assess the prevalence of T. gondii in sheep (serology), lambs (serology, bioassay, PCR) and sheep abortions (PCR) in Romania. Moreover, the study aimed to perform the genetic characterization of T. gondii isolates from lambs.

METHODS

Serum samples collected from 2650 sheep (2067 adults and 583 lambs) were tested for anti-T. gondii antibodies (IgG) using a commercial ELISA kit. Likewise, 328 pairs of diaphragmatic muscle-serum samples were collected from lambs aged between 2 and 4 months. Lamb serum samples were analyzed using MAT for anti-T. gondii antibody detection. The diaphragm tissue samples from MAT-positive lambs (at a dilution ≥ 1:25) were bioassayed in mice. The T. gondii strains were genotyped using 15 microsatellites markers. Additionally, brain and heart samples from 76 sheep abortions were analyzed for T. gondii DNA by polymerase chain reaction (PCR) targeting the 529-bp repeat region (REP529).

RESULTS

The results showed that more than half of the tested sheep were T. gondii seropositive (53.5%). The seroprevalence was significantly higher in adults (61.1%) than in lambs (26.4%). The seroprevalence of T. gondii infection in slaughtered lambs, by MAT, was 37.5% (123/328). There were bioassayed in mice 56 diaphragmatic tissues from 123 seropositive lambs. Toxoplasma gondii strains were isolated from 18 (32.1%) lambs intended for human consumption. All T. gondii strains were confirmed by PCR. Six strains were genotyped using 15 microsatellite markers and belonged to genotype II. Toxoplasma gondii DNA was detected in 11.8% (9/76) of sheep abortions.

CONCLUSIONS

The present study showed the presence of T. gondii in sheep in all the regions considered in the study. The high prevalence of T. gondii infection in sheep and lambs, demonstrated by serology, molecular analysis and bioassay, highlighted that there is an important risk of human infection in consuming raw or undercooked sheep/lamb meat.

Molecular prevalence, genetic characterization and patterns of Toxoplasma gondii infection in domestic small mammals from Cotonou, Benin

Toxoplasmosis, one of the most prevalent parasitic infections in humans and animals, is caused by the intracellular protozoan parasite Toxoplasma gondii. Small mammals play a key role as intermediate reservoir hosts in the maintenance of the T. gondii life cycle. In this study, we estimated the molecular prevalence and provide genetic diversity data for T. gondii in 632 small mammals sampled in four areas of Cotonou city, Benin. Both the brain and heart of each individual were screened through T. gondii-targeting qPCR, and positive samples were then genotyped using a set of 15 T. gondii-specific microsatellites. Prevalence data were statistically analyzed in order to assess the relative impact of individual host characteristics, spatial distribution, composition of small mammal community, and urban landscape features. An overall T. gondii molecular prevalence of 15.2% was found and seven genotypes, all belonging to the Africa 1 lineage, could be retrieved from the invasive black rat Rattus rattus and the native African giant shrew Crocidura olivieri. Statistical analyses did not suggest any significant influence of the environmental parameters used in this study. Rather, depending on the local context, T. gondii prevalence appeared to be associated either with black rat, shrew, or mouse abundance or with the trapping period. Overall, our results highlight the intricate relationships between biotic and abiotic factors involved in T. gondii epidemiology and suggest that R. rattus and C. olivieri are two competent reservoirs for the Africa 1 lineage, a widespread lineage in tropical Africa and the predominant lineage in Benin.

Réponse sérologique après vaccination contre le coronavirus chez les patients atteints de rhumatisme inflammatoire chronique traités par DMARDs : une étude de cohorte et revue systématique avec méta-analyse

Introduction

La vaccination contre le coronavirus constitue l’une des pierres angulaires dans la gestion de la crise sanitaire liée au COVID-19. Alors que la vaccination confère une protection efficace chez les sujets immunocompétents, son immunogénicité dans la population atteinte de rhumatisme inflammatoire chronique (RIC) n’est pas clairement établie.

Patients et méthodes

Nous avons conduit une étude monocentrique rétrospective évaluant la réponse sérologique après deux doses de vaccination contre le coronavirus chez des patients adultes atteints de RIC et traités par traitements ciblés ou biologiques (n = 123). Les titres d’anticorps IgG dirigés contre la protéine spike du coronavirus (SARS-CoV-2) ont été mesurés après la seconde dose de vaccin. De plus, nous avons conduit une recherche systématique jusqu’au 31 septembre 2021 dans les bases de données PUBMED, preprint et littérature grise non encore publiée des études observationnelles des taux sérologiques après vaccination chez des patients atteints de RIC traités par médicaments ciblés ou biologiques (numéro d’enregistrement PROSPERO : CRD42021259410). Les études rapportant la taille d’échantillon, la date, le pays d’origine, le taux de séroconversion ont été incluses. Nous avons ensuite conduit une méta-analyse afin d’identifier des facteurs associés à la séroconversion.

Résultats

Sur nos 123 patients (âge médian 66 ans écart interquartile [EI] 57–75), 69,9 % ont séroconverti après 2 doses de vaccination. Les patients ayant eu une séroconversion étaient plus âgés que ceux qui n’en ont pas eu. Les patients traités par rituximab sont ceux qui ont le moins répondu à la vaccination. Nous avons identifié 20 études de séroprévalence en plus de notre cohorte, représentant un total de 4423 patients dans 11 pays. La méta-analyse a confirmé un impact négatif sur le taux de séroconversion du rituximab et dans une moindre mesure de l’abatacept, du léflunomide et du méthotrexate.

Conclusion

Le rituximab diminue la réponse sérologique à la vaccination contre le SARS-CoV-2 chez les patients atteints de RIC. Ce travail suggère également un impact négatif de l’abatacept, du méthotrexate ou du léflunomide particulièrement en cas d’association à un médicament biologique.

Toxoplasma gondii in the faeces of wild felids from the Atlantic Forest, Brazil

BACKGROUND

Toxoplasma gondii is a apicomplexan parasite of virtually all warm-blooded species. All true cats (Felidae) can act as definitive hosts for this parasite by shedding resistant oocysts into the environment. However, the patterns of oocysts shedding are only partially understood in domestic cats and largely unknown in wild felids.

OBJECTIVES

We carried out molecular analysis of 82 faecal samples from wild felids collected in the Serra dos Órgãos National Park (Parnaso), Rio de Janeiro, Brazil.

METHODS

We screened samples for T. gondii DNA using a quantitative polymerase chain reaction (qPCR) targeting the 529bp DNA fragment. Polymerase chain reaction (PCR)-positive samples were genotyped using 15 microsatellite markers.

RESULTS

Only one faecal sample from a Puma yagouaroundi was PCR-positive [cycle threshold (Ct) = 26.88]. This sample was contaminated by a T. gondii strain of BrIII lineage, a common lineage in domestic animals from Brazil.

MAIN CONCLUSIONS

This first report of T. gondii in faeces of wild South American felids in their natural environment indicates infrequent oocyst shedding and suggests a role of acquired immunity in limiting re-excretion as in domestic cats. The presence of a domestic strain of T. gondii in a faecal sample from a wild felid at very low concentrations (not detected by microscopy) is consistent with the hypothesis of host-parasite co-adaptations limiting the circulation of T. gondii strains between domestic and wild environments.

Vagues épidémiques de variants Beta, Delta et Omicron en milieu insulaire ultra-marin

Introduction

Dans cette région d'Outre-Mer, une surveillance génomique a été mise en place en janvier 2021 suite à l'émergence de variants du SARS-CoV-2. Elle se compose d'une surveillance génomique locale et des enquêtes Flash nationales. La surveillance génomique vise à cartographier la circulation de variants sur l'île, et s'inscrit dans le cadre du projet EMERGEN (Consortium pour la surveillance et la recherche sur les infections à pathogènes EMERgents via la GENomique microbienne). Elle permet également de détecter l'introduction et de suivre la diffusion de variants d'intérêt ayant un impact en termes de transmissibilité, de sévérité ou d'échappement immunitaire accrus.

Matériels et méthodes

Du 04 janvier 2021 au 30 janvier 2022, 11 341 génomes ont été séquencés et soumis à EMERGEN, soit 5,6 % des cas de COVID-19 sur la période. La sélection de prélèvements à séquencer était aléatoire pour l'enquête Flash (une certaine proportion des prélèvements sur une période définie) et pseudo-aléatoire pour la surveillance génomique locale qui cible des cas particuliers en fonction de caractéristiques épidémiologiques ou cliniques atypiques (ex : cas importés, cas graves).

Résultats

Au total, 110 lignages et sous-lignages du SARS-CoV-2 ont été identifiés, dont 68 sous-lignages du variant Delta (B.1.617.2). Pendant les six premières semaines de l'année 2021, la majorité des lignages détectés correspondait à des variants circulant activement en Europe (ex : B.1.160, B.1.177), illustrant l'impact des flux de voyageurs sur la dynamique de la COVID-19 sur l'île. Selon les données de la base de données GISAID (Global Initiative on Sharing All Influenza Data), le lignage B.1.622 semble être spécifique à l'île car aucun autre territoire n'a identifié de séquences de ce variant.

Trois variants d'intérêt ont été dominants pendant plusieurs semaines sur l'île et représentent à eux-seuls 95 % des séquences. Il s'agit du variant Beta (B.1.351 et B.1.351.2) prédominant de février à mi-juillet 2021 (29 % des séquences), le variant Delta (B.1.617.2 et sous-lignages AY) prédominant de mi-juillet à fin décembre 2021 (53 %) et le variant Omicron (B.1.529, BA.1 et BA.2) prédominant depuis fin décembre 2021 (13 %).

Ces trois variants ont influencé différemment la dynamique de l'épidémie et son impact sanitaire. Le taux d'incidence a atteint un plateau élevé de 100 et 150 cas pour 100 000 habitants en période de prédominance Beta, un pic de 397/100 000 hab en période de prédominance Delta et 5 431/100 000 hab en période de prédominance Omicron.

Conclusion

Cette étude permet de mieux comprendre les interactions entre les variants du SARS-CoV-2 et l'impact qu'ils peuvent avoir sur l'évolution de l'épidémie. Elle illustre aussi l'impact des flux de voyageurs sur la dynamique de la COVID-19 en milieu insulaire, et ouvre des perspectives de travaux en épidémiologie génomique pour mieux comprendre les mécanismes d'émergence d'un variant dominant et l'impact en termes de sévérité et d'échappement vaccinal de ces variants préoccupants plus transmissibles.

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Circulation des variants du SARS-CoV-2 en milieu insulaire ultra-marin

Introduction

Dans cette région d'Outre-Mer, les premiers cas de COVID-19 ont été détectés le 11 mars 2020 chez un groupe de personnes de retour de voyage. En réponse, une surveillance épidémiologique régionale basée sur le « contact-tracing » et l'identification de clusters a rapidement été mise en place. De mars à juillet 2020, les cas ont été importés ou autochtones sporadiques, puis la circulation virale s'est intensifiée sur l'île à partir d'août 2020 à la fin des vacances scolaires. En janvier 2021, une surveillance génomique locale a été mise en place suite à l'émergence de variants du SARS-CoV-2.

Matériels et méthodes

Du 04 janvier 2021 au 06 juin 2021, 1 528 génomes ont été séquencés, soit 8,3 % des cas de COVID-19 sur la période. La sélection de prélèvements à séquencer était pseudo-aléatoire, avec une sélection ciblée en fonction de caractéristiques épidémiologiques ou cliniques atypiques (ex : cas importés, cas graves). Les distributions de lignages génétiques dans l'Océan indien et dans certains pays d'Afrique ont été extraites de la base de données GISAID (Global Initiative on Sharing All Influenza Data).

Résultats

Au total, 22 lignages du SARS-CoV-2 ont été identifiés et 71 % des observations étaient attribuées au variant Beta (B.1.351 et B.1.351.2). Ce variant a été détecté pour la première fois la première semaine de janvier 2021, dès le lancement des activités de séquençage. Pendant les six premières semaines de l'année 2021, la majorité des lignages détectés correspondait à des variants circulant activement en Europe (ex : B.1.160, B.1.177), illustrant l'impact des flux de voyageurs sur la dynamique de la COVID-19 sur l'île. Selon les données GISAID, le lignage B.1.622 serait spécifique à l'île car aucun autre territoire n'a identifié de séquences de ce variant.

Le variant Beta est devenu dominant à partir de mi-février 2021, malgré une circulation à bas-bruit du variant Alpha (B.1.1.7) qui était alors dominant en métropole. En plus de sa transmissibilité accrue, d'autres facteurs génétiques et épidémiologiques auraient pu expliquer la dominance du variant Beta, dont une fréquence d'introduction plus importante (flux de voyageurs) et les contextes locaux et régionaux. En effet, la proximité géographique et les mouvements de population avec d'autres îles de la région relient indirectement l'île au pays d'où serait originaire le variant Beta.

Deux sous-lignages du variant Beta ont été détectés. B.1.351.2 représentait trois fois plus de séquences que B.1.351. Les données disponibles dans GISAID suggèrent qu'il aurait été importé depuis son pays d'origine vers d'autres îles de l'Océan indien avant d'être introduit sur l'île, compte tenu des flux de voyageurs entre les régions concernées et l'importante épidémie liée variant Beta ayant eu lieu sur une île voisine de janvier à mi-mars 2021.

Conclusion

Cette étude permet de mieux comprendre les interactions entre les variants du SARS-CoV-2 sur l'île, qui représente un système fermé avec contrôle des entrées. L'étude illustre aussi l'impact des flux de voyageurs sur la dynamique de la COVID-19 en milieu insulaire, et ouvre des perspectives de travaux en épidémiologie génomique pour mieux comprendre les mécanismes d'émergence de variants dominants.

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Impact of temperature on dengue and chikungunya transmission by the mosquito Aedes albopictus

The mosquito Aedes albopictus is an invasive species first detected in Europe in Albania in 1979, and now established in 28 European countries. Temperature is a limiting factor in mosquito activities and in the transmission of associated arboviruses namely chikungunya (CHIKV) and dengue (DENV). Since 2007, local transmissions of CHIKV and DENV have been reported in mainland Europe, mainly in South Europe. Thus, the critical question is how far north transmission could occur. In this context, the Albanian infestation by Ae. albopictus is of interest because the species is present up to 1200 m of altitude; this allows using altitude as a proxy for latitude. Here we show that Ae. albopictus can transmit CHIKV at 28 °C as well as 20 °C, however, the transmission of DENV is only observed at 28 °C. We conclude that if temperature is the key environmental factor limiting transmission, then transmission of CHIKV, but not DENV is feasible in much of Europe.

Development of a new serotyping ELISA for Toxoplasma gondii type II, type III and Africa 1 lineages using in silico peptide discovery methods, well categorized feline and human outbreak serum samples

BACKGROUND

Discovery of new Toxoplasma gondii serotyping epitopes is important due to reports showing the influence of genotype on the severity of toxoplasmosis. In Turkey, genotypes belonging to type II, type III and Africa 1 lineages were mainly detected. The present study focused on to find out epitopes with high discriminative capacity to serotype these genotypes using well characterized strains isolated from Turkey.

METHODS

To meet this objective, GRA6 and GRA7 genes were sequenced from strains belonging to the type II, III and Africa 1 lineages, and B cell epitopes inside these sequences were predicted by Bcepred and additional docking analysis was performed with B cell receptor. Based on these analyses, 22 peptides harboring lineage specific epitopes were synthesized. Then, the serotyping potency of these peptides was tested using peptide ELISA and well categorized serum samples collected from stray cats infected with genotypes of the different lineages type II (n:9), III (n:1) and Africa 1 (n:1). As a result of peptide-ELISA, a serotyping schema was constructed with peptides that show high discriminative capacity and this assay was validated by sera collected from humans after an outbreak (n:30) and mother/newborn pair sera (n:3). Later, the validated serotyping schema was used to serotype a larger group of human (n:38) and cat (n:24) sera.

RESULTS

Among 22 peptides, GRA6II/c, GRA7III/d, and GRA6 Africa 1/b epitopes have shown discriminative capacity. During the validation of peptide-ELISA, the serotype of toxoplasmosis outbreak and mother/newborn cases were detected to be serotype II. Moreover, the analyses in a larger group showed that serotype II was prevalent in humans and stray cats.

CONCLUSIONS

Overall, the results showed that the serotyping schema could be successfully used to serotype T. gondii infections caused by type II, III and Africa 1 genotype.

A hotspot of Toxoplasma gondii Africa 1 lineage in Benin: How new genotypes from West Africa contribute to understand the parasite genetic diversity worldwide

Through international trades, Europe, Africa and South America share a long history of exchanges, potentially of pathogens. We used the worldwide parasite Toxoplasma gondii to test the hypothesis of a historical influence on pathogen genetic diversity in Benin, a West African country with a longstanding sea trade history. In Africa, T. gondii spatial structure is still non-uniformly studied and very few articles have reported strain genetic diversity in fauna and clinical forms of human toxoplasmosis so far, even in African diaspora. Sera from 758 domestic animals (mainly poultry) in two coastal areas (Cotonou and Ouidah) and two inland areas (Parakou and Natitingou) were tested for T. gondii antibodies using a Modified Agglutination Test (MAT). The hearts and brains of 69 seropositive animals were collected for parasite isolation in a mouse bioassay. Forty-five strains were obtained and 39 genotypes could be described via 15-microsatellite genotyping, with a predominance of the autochthonous African lineage Africa 1 (36/39). The remaining genotypes were Africa 4 variant TUB2 (1/39) and two identical isolates (clone) of Type III (2/39). No difference in terms of genotype distribution between inland and coastal sampling sites was found. In particular, contrarily to what has been described in Senegal, no type II (mostly present in Europe) was isolated in poultry from coastal cities. This result seems to refute a possible role of European maritime trade in Benin despite it was one of the most important hubs during the slave trade period. However, the presence of the Africa 1 genotype in Brazil, predominant in Benin, and genetic analyses suggest that the triangular trade was a route for the intercontinental dissemination of genetic strains from Africa to South America. This supports the possibility of contamination in humans and animals with potentially imported virulent strains.

The parasite Toxoplasma gondii is a worldwide-distributed pathogen, able to infect all warm-blooded animals. There are important differences in the clinical expression of the infection in direct relation with the parasite genetic profile. In some regions, the geographical structuration of its genetic diversity points towards a crucial role of human activities in some lineages introduction or sorting. Benin is a West African country with a history of extensive transcontinental exchanges. Our genetic study of Toxoplasma in Benin shows a surprisingly homogeneous and autochthonous diversity, which contrasts with previous studies from other West and Central African countries. In Benin, the absence of European Toxoplasma lineages may be explained by the extreme rarity of the house mouse (Mus musculus), a host species that was previously described as highly susceptible to the mouse-virulent African strains. Might Benin be the origin region for the Africa 1 lineage, our results suggest that Guinean Gulf coasts may be a starting point of this lineage towards South America, especially Brazil, during the slave trade. As a whole, the present study provides further insights into the recent evolutionary history of Toxoplasma gondii and its consequences on human and animal health.

Seroprevalence of Toxoplasma gondii among healthy blood donors in two locations in Tunisia and associated risk factors

Toxoplasma gondii is a protozoan parasite that can be transmitted to humans through a variety of routes including blood transfusion. This study aimed to investigate the seroprevalence of T. gondii infection and associated risk factors in healthy blood donors in Tunisia. A total of 800 healthy blood donors from two blood centers in south and coastal Tunisia were analyzed for anti-T. gondii IgG and IgM antibodies by indirect immunofluorescence assay (IFA) and enzyme-linked immunoassays (ELISA), respectively. Structured questionnaires were used to gather information on risk factors for T. gondii infection during collection. The overall seroprevalence was 44.4% of which 352 (44%) and 3 (0.4%) were positive for IgG and both IgG and IgM anti-T. gondii antibodies, respectively. Multivariate analysis showed that T. gondii seropositivity was significantly associated with the birth place (adjusted odds ratio [OR] = 2.72; 95% confidence interval [CI]: 1.49–4.94) and the age of the donors (adjusted OR = 4.98; 95% CI: 1.50–16.58) which are independent risk factors. In addition, the variables of hand washing before eating (adjusted OR = 0.52; 95% CI: 0.37–0.74) and living in an urban environment (adjusted OR = 0.30; 95% CI: 0.13–0.71) are two protective factors. This study provided the first data on the seroprevalence and epidemiology of T. gondii infection in healthy blood donors in Tunisia.

Outbreak of Amazonian Toxoplasmosis: A One Health Investigation in a Remote Amerindian Community

Background:Toxoplasma gondii is a parasite of worldwide importance but its burden in indigenous communities remains unclear. In French Guiana, atypical strains of T. gondii originating from a complex rainforest cycle involving wild felids have been linked to severe infections in humans. These cases of Amazonian toxoplasmosis are sporadic and outbreaks are rarely described. We report on the investigation of an outbreak of acute toxoplasmosis in a remote Amerindian village. We discuss the causes and consequences of this emergence.

Methods: In May 2017, during the rainy season and following an episode of flooding, four simultaneous cases of acute toxoplasmosis were serologically confirmed in two families living the village. Other non-diagnosed cases were then actively screened by a medical team along with epidemiological investigations. Inhabitants from nine households were tested for T. gondii antibodies and parasite DNA by PCR when appropriate. Samples of water, cat feces and cat rectal swabs, soil, and meat were tested for T. gondii DNA by PCR. Positive PCR samples with sufficient DNA amounts were genotyped using 15 microsatellite markers.

Results: Between early May and early July 2017, out of 54 tested inhabitants, 20 cases were serologically confirmed. A fetus infected at gestational week 10 died but other cases were mild. Four patients tested positive for parasite DNA and two identical strains belonging to an atypical genotype could be isolated from unrelated patients. While domestic cats had recently appeared in the vicinity, most families drank water from unsafe sources. Parasite DNA was recovered from one water sample and nine soil samples. Three meat samples tested positive, including wild and industrial meat.

Conclusions: The emergence of toxoplasmosis in such a community living in close contact with the Amazon rainforest is probably multifactorial. Sedentary settlements have been built in the last few decades without providing safe water sources, increasing the risk of parasite circulation in cases of dangerous new habits such as cat domestication. Public health actions should be implemented in these communities such as safe water supply, health recommendations, and epidemiological surveillance of acute toxoplasmosis. A “One Health” strategy of research involving medical anthropology, veterinary medicine, and public health needs to be pursued for a better understanding of the transmission routes and the emergence of this zoonosis.

Combining spatial analysis and host population genetics to gain insights into the mode of transmission of a pathogen: The example of Toxoplasma gondii in mice

Toxoplasma gondii is a ubiquitous highly prevalent zoonotic protozoan. Cats are the definitive hosts, while all other warm-blooded animals are intermediate hosts for this parasite. Commensal rodents, being the main prey of cats, are probably the major reservoir for T. gondii in the domestic environment. Rodents can acquire infection after ingestion of oocysts that have sporulated in the environment. However, experimental evidence shows that vertical transmission can be sufficient for the perpetuation of transmission between generations of mice. In natural settings, the relative epidemiological importance of vertical transmission over oral transmission is a matter of debate and raises the question of the possibility of a T. gondii cycle in the absence of cats. In the present study, we took advantage of an extensive survey of commensal rodents in Dakar, Senegal, where the house mouse is the predominant putative reservoir of T. gondii. Mice genotypes and spatial location through GPS referencing of all trapping localizations were investigated in relation to T. gondii infection in eight sites of the city of Dakar and on Goree Island. In each sampling site, the occurrence of over-prevalence zones of T. gondii infection was investigated through Kulldorf's statistic using SaTScan software. Genetic structure and relatedness between mice were investigated within each over-prevalence zone, in order to find clues of transmission between related mice. Within each of the four over-prevalence zones identified across nine sites, infected mice belonged to more than one genetic group. No association between the degree of relatedness and the occurrence of T. gondii infection could be detected. These findings suggest an environmental source of infection for mice associated with localized putative foci of environmental contamination and support an oral route of infection for mice from Dakar rather than a cycle based on vertical transmission. However, further investigations based on a denser sampling in different epidemiological contexts are recommended.

Molecular Study of Toxoplasma gondii Isolates Originating from Humans and Organic Pigs in Belgium

Toxoplasma gondii is a worldwide prevalent, zoonotic parasite of major importance for public health, which can infect any warm-blooded animal species, including humans. Humans can get infected by consumption of meat from a chronically infected animal, by ingestion of sporulated oocysts (resulting from the sexual replication in felids), via contaminated water, soil, or vegetables, and by vertical transmission via the placenta. Infection through meat consumption is estimated to be one of the main sources of human toxoplasmosis cases in developed countries, and more specifically pork is considered to be responsible for 41% of foodborne human toxoplasmosis cases in the United States. To better assess the role of pork as a source of T. gondii infection in humans in Belgium, parasites were isolated from pigs to compare with human clinical isolates in a molecular epidemiological study. A positive result was obtained by magnetic capture-quantitative polymerase chain reaction for T. gondii in 14 out of the 92 hearts sampled during 2016 and 2017 from pigs raised in organic farms. From 9 of these 14 samples, parasites were isolated by mouse bioassay, demonstrating the presence of viable T. gondii in animals intended for human consumption. When genotyped and compared with 15 human isolates obtained during 2015 and 2016, a highly related structured population was demonstrated. Overall, these findings demonstrate the presence of infectious T. gondii in pigs intended for human consumption. Therefore, a potential transmission of T. gondii strains from pigs to humans could occur. However, both species could also be infected via a common source of infection such as oocysts. Furthermore, Belgium does not have an official surveillance program for T. gondii in human cases or food-producing animals; as a consequence, the detection of the infection source of a patient is very rare. Overall, this study reinforces the identification of pork as a potential risk for the consumers.

Toxoplasma gondii in beef consumed in France: regional variation in seroprevalence and parasite isolation

In France, the consumption of cattle and sheep meat appears to be a risk factor for infection of pregnant women with Toxoplasma gondii. Several nation-wide surveys in France have investigated the prevalence of T. gondii in sheep and pig meat, but little is known at present about the prevalence of the parasite in beef. The main objective of the present cross-sectional survey was to estimate the seroprevalence of T. gondii infection in beef consumed in France. A secondary objective was to attempt to isolate T. gondii from cattle tissues and to study the geographical and age variations of this seroprevalence. The overall estimate of seroprevalence of T. gondii in bovine carcasses (n = 2912), for a threshold of 1:6 was 17.38%. A strong age effect was observed (p < 0.0001) with a seroprevalence of 5.34% for calves (<8 months) and 23.12% for adults (>8 months). Seroprevalence estimates given by area of birth and area of slaughtering for adults showed that the areas with the highest seroprevalence were not the same between these two variables. Only two strains, corresponding to genotype II, were isolated from heart samples, indicating that there is a limited risk of human infection with T. gondii, which needs to be correlated with the food habit of consuming raw or undercook (bleu or saignant) beef. However, new questions have emerged, especially concerning the isolation of parasites from beef and the precise role of bovines, generally described as poor hosts for T. gondii, in human infection.