Parasite Load Research Articles

Impact of anticoccidial treatment with Solo papaya seed powder on haematological parameters in Sasso broilers Komlan Mawouli Wampah 1, 3, Kosi M

Coccidiosis is a highly contagious and damaging poultry disease. Despite its effectiveness against coccidiosis, chemotherapy has not been able to overcome certain difficulties, in particular the phenomenon of bioresistance acquired by the parasites, the rising price of anticoccidials, and the contamination of poultry products by toxic residues that are dangerous for consumers. As an alternative solution, Carica papaya is emerging as an interesting and less costly natural substance for eradicating coccidiosis. Our study aimed to evaluate the anticoccidial efficacy of the seed of Solo papaya and its effects on haematological parameters in Sasso broilers. Six-hundred-day-old chicks of Sasso breed, broiler type, were divided into four batches with five replicates per batch: untreated batch (T-), batch treated with amprolium 20% (T+), and two batches treated with papaya seed powder (5%), incorporated into the feed for one and two consecutive days per month, noted P1 and P2 respectively. Determination of number of eggs per gram (EPG) was based on Mc Master technique. Haematological parameters were determined from blood collected in tubes containing EDTA using Mindray BC-3000/China automated haematological analyser. Papaya seed powder Treatment showed anticoccidial efficacy, expressed by a significant drop in EPG in the treated batches. In addition, haematological parameters improved, notably an increase in haematocrit and a decrease in the rate of various leucocytes. Anticoccidial treatment with papaya seed powder (5%) resulted in an appreciable reduction in parasite load and an improvement in the haematological profile. The result application could serve as a sustainable alternative to synthetic chemical anticoccidial drugs.

Giardia lamblia risk factors and burden in children with acute gastroenteritis in a Nicaraguan birth cohort.

Giardia lamblia is an intestinal protozoan estimated to cause ~200 million symptomatic infections annually, mainly in children in low- and middle-income countries associated with intestinal damage, increased permeability, and malabsorption. We describe here the epidemiology, incidence, clinical characteristics, and risk factors of acute gastroenteritis episodes (AGE) with G. lamblia detection (GAGE) using a birth cohort of 443 Nicaraguan children followed weekly until 36 months of life. From June 2017 to July 2021, 1385 AGE samples were tested by qPCR. G. lamblia was detected in 104 (7.5%) of AGE episodes. In all, 69 (15.6%) children experienced at least one GAGE episode, and 25 of them (36.2%) experienced more than one episode. The incidence rate of the first episode of GAGE was 6.8/100 child-years (95% CI, 4.5-9.1). During GAGE, bloody stools, vomiting, and fever were uncommon, and children were less likely to be treated at a primary care clinic, suggesting that GAGE is typically mild and most cases did not receive medical attention, which could facilitate higher parasite loads with increased possibilities of establishing chronic carriage. GAGE was more common in children 12-24 months of age (13.9/100 child-years [95% CI, 10.7-17.1]) as compared to other age groups. In our birth-cohort, children living in a home with an indoor toilet (aHR, 0.52 [95%CI, 0.29-0.92]), and being breastfed in the first year of life (aHR: 0.10 [95%IC, 0.02, 0.57]) had a lower incidence of GAGE. In contrast, being breastfed for ≤ 6 months was associated with a higher incidence if the children were living in houses without indoor toilets and earthen floors (HR, 7.79 [95% CI, 2.07, 29.3]). Taken together, GAGE is more frequent under poor household conditions. However, breastfeeding significantly reduces the incidence of GAGE in those children.

The Sexual Dimorphism of the Neuroimmune Response in the Brains of Taenia crassiceps-Infected Mice

Background: Helminth infections are associated with cognitive deficits, especially in school-age children. Deworming treatment in heavily infected children improves their short- and long-term memory recall. In mice, intraperitoneal helminth infection with Taenia crassiceps (T. crassiceps) shows sexual dimorphism in terms of the parasite load, immune response, hormone levels, and behavioral changes. We have previously shown poorer short-term memory performance and changes in the concentrations of cytokines and neurotransmitters in the hippocampus, which were replicated in this study. The molecular changes in other brain structures, such as those related to reproduction, are unknown. Methods: Male and female Balb/cAnN mice were chronically infected with T. crassiceps larvae. We determined the peritoneal parasite load and established the presence of cytokines and neurotransmitters in the hippocampus, olfactory bulb, and hypothalamus. Results: The parasite load was higher in female than male infected mice, as expected. In the hippocampus, the neurotransmitters norepinephrine and serotonin increased in males but decreased in females. In contrast, in the olfactory bulb and hypothalamus, the neurotransmitters assessed showed no statistical differences. The cytokine profiles were different in each brain structure. The TNF-α levels in the olfactory bulb and the IL-4 levels in the hippocampus of infected mice were dimorphic; IFN-γ was augmented in both male and female infected animals, although the increase was higher in infected males. Conclusions: The brain responds to peripheral infection with cytokine levels that vary from structure to structure. This could be a partial explanation for the dimorphic behavioral alterations associated with infection, it also demonstrates the synergic interaction between the immune, the endocrine, and the nervous systems.

Prevalence of intestinal parasites in street dwellers attending a shelter in Cali, Colombia.

Intestinal parasitic infections represent a public health problem, especially among vulnerable populations. There are few studies on the prevalence and determinants of intestinal parasites infections in street dwellers, who may experience significant health and socioeconomic implications. Understanding the prevalence and associated factors of intestinal parasites in this population is crucial for targeted interventions to mitigate the spread of these infections. To determine the prevalence of intestinal parasites in street dwellers attending a shelter in Cali, Colombia. We selected 66 participants who met the inclusion criteria. We collected serial stool samples for laboratory evaluation and sociodemographic data, and information on their hygiene habits and addictions. Seventy-six percent of the participants had intestinal parasites or commensals, with 30% presenting monoparasitism, 46% polyparasitism, and 20% eosinophilia. Blastocystis spp. was the most common organism (68.18%), followed by Endolimax nana (34.85%) and Entamoeba coli (18.18%). The most common pathogens were the Entamoeba histolytica/E. dispar/E. moshkovskii complex (10.61%) and hookworms (9.09%). We evaluated prevalence-related determinants. Intestinal parasitism is a health problem among street dwellers in Cali. A serial examination is recommended for diagnosing intestinal parasitic infection, especially in cases of low parasite loads. Campaigns should be established to reduce the prevalence of these parasites in populations at risk of complications.

Unveiling the potential of parasites as proxy bioindicators for water quality assessment in river Jhelum Kashmir, India.

This study aimed to evaluate the effects of deteriorated physicochemical conditions in the river Jhelum on parasitic infestations and to investigate the potential of fish parasites as bioindicators of water quality. All the physicochemical parameters exhibited statistically significant differences based on both site and season (p < 0.01).The interaction term (Site × Season) was also kept in the model since it was statistically significant (p < 0.01). A parasitological survey of 360 schizothoracine fish revealed a 30.3% prevalence (109/360) of endohelminth infection. The study identified four predominant parasitic taxa across two distinct classes: Cestoda, including Adenoscolex oreini and Schyzocotyle acheilognathi, and Acanthocephala, comprising Pomphorhynchus kashmirensis and Neoechinorhynchus manasbalensis. For the assessment of parasitic load, we calculated the prevalence, mean intensity, mean abundance, and index ofinfection for each sampling period. Correspondence analysis identified associations between parasite occurrence and specific water quality parameters. Regression analysis, including R2 and p values, demonstrated a positive correlation between the number of parasites and both the proportion of infected fish and the ratio of infected to examined fish. Given that parasitic load is significantly influenced by a range of water quality parameters, fish parasites can serve as a robust indicator of declining water quality. Fish parasites are highly sensitive to water quality changes such as pollutants, toxins, and fluctuations in pH, temperature, and oxygen levels. Deteriorating water quality can stress fish, compromising their immune systems and increasing their susceptibility to parasitic infections. Additionally, complex life cycles of parasites can be disrupted by poor water conditions, making them indicators of water quality issues.

Effects of individual characteristics and seasonality and their interaction on ectoparasite load of Daurian ground squirrels in Inner Mongolia, China

Understanding the drivers of parasite distribution is vital for ecosystem health, disease management, and vector monitoring. While studies note the impact of host sex, size, behavior, and season on parasite load, concurrent assessments of these factors and their interactions are limited. During the spring, summer and autumn seasons from 2021 to 2023, we trapped Daurian ground squirrel (Spermophilus dauricus), a small rodent species that inhabits eastern Asian grasslands in Inner Mongolia and collected their ectoparasites. Using machine learning Lasso regression, we pinpointed factors affecting tick and flea abundance on S. dauricus. We then analyzed these factors and their seasonal interactions with a mixed negative binomial generalized linear model. Our study revealed significant but inconsistent seasonal effects on the load of ectoparasites. The tick load was significantly higher in spring and summer compared to autumn, while the flea load was higher in summer and autumn but lacked statistical significance. Furthermore, individual factors that influence the flea and tick load were moderated by seasonal effects, with a male bias in flea parasitism observed in spring. Significant interactions were also found among seasonality, sex, and body weight. The load of male squirrel fleas was positively correlated with body weight, with the highest increase observed in spring. On the contrary, the flea load of female squirrels showed a negative correlation with body weight, significantly decreasing in the autumn with increasing weight. Significant interactions were observed between season and survival status, with hosts exhibiting higher tick load during autumn survival. Our findings underscore the importance of considering seasonal variation in parasitism and the interactions between seasonal dynamics and host biological traits in shaping parasite distributions.

Some ecological aspects of Monogeneans (Platyhelminthes) ectoparasites of Enteromius guirali Thominot, 1886 (Pisces: Cyprinidae) from Cesala River in Cameroon.

Fish are exposed to various parasites such as monogeneans which are flatworms that preferentially affect the gills and skin of these hosts. This study represents the first investigation concerning the distribution of monogenean infracommunities of Enteromius guirali in Cameroon. A total of 100 fish were collected from Cesala River and preserved in 8% formalin solution. Parasite community consisted of Dactylogyrus mendehei and D. nyongensis. These monogenean species adopted an aggregated distribution. Their mean intensities and prevalence increased with host size. Both sides of E. guirali were similarly infested, and no preference for gill arches was recorded for each parasite species. Posterior hemibranch was always the most parasitized, showing the highest parasitic load. Median sector and distal filamentous zone were highly colonized by both monogenean species. This study contributes to understand that the large gill surface offered by great hosts, heterogeneity, bilateral symmetrically of the host's gill system on one hand, and the morphology of haptoral parts and reproduction of parasites, on the other hand, are the main factors which determine the distribution of studied component community.

The Prevalence of Blastocystis Hominis and Gastrointestinal System Parasites in Patients With Newly Diagnosed Multiple Myeloma Diagnosis

Introduction: Multiple myeloma (MM) is a hematological malignancy characterized by the presence of abnormal clonal plasma cells in the bone marrow. Immunodeficiency seen in patients with multiple myeloma (MM) is a serious problem. Blastocystis sp. is found in the gastrointestinal tract and can infect humans. Background/ Aims: In our study, we compared the prevalence of B.hominis and other parasites with the control group and patients who had recently been diagnosed with multiple myeloma. Material-Methods: Ninety-five multiple myeloma patients from our center and 95 volunteers as a control group were included in our study. The patients did not have any symptoms when stool samples were taken. For B.hominis, three consecutive stool samples were examined by saline-lugol trichrome staining and formalin-ethyl acetate concentration. Data were recorded and analyzed using SPSS 25.0. Results: Patients with newly diagnosed multiple myeloma and any of the patients in the control group did not have any parasites other than B.hominis. A significant difference was found between the newly diagnosed MM patients and the control group in terms of the number of B.hominis occurrences in the stool (p &amp;lt;0.001). Conclusions: According to this result, parasite load in stool increased in patients with MM. This result may reflect the suppression of the immune system of patients with MM. Accordingly, B.hominis should be considered as a causative agent in the presence of gastrointestinal symptoms that may occur during treatment in patients with MM.

In vitro gas production, in situ digestibility, intake, weight gain and ruminal characteristics of calves fed a diet containing 60% waste papaya silage.

Our aim was to evaluate a whole-grain diet containing 0 (T1) and 60% (T2) waste papaya silage in vitro, in situ and in vivo. In vitro, biogas, methane and dry matter degradation (DMDiv), neutral detergent fiber (NDFDiv) and crude protein (CPDiv) were determined at 72h; in situ, DM (DMDis), NDF (NDFis) and CP (CPDis) digestibility was determined at 72h; in vivo, consumption and apparent digestibility of DM (DMI and DMD) and NDF (NDFI and NDFD), daily weight gain (DWG), rumen characteristics (pH, bacterial and protozoan counts) were determined. In addition, we performed coproparasitoscopic analysis and interviews with producers. Biogas production, methane, DMDiv, CDPiv, DMDis, DMD, NDFD, pH, bacterial and protozoan counts, and parasite load of nematodes and coccidia were not different between treatments (p > 0.05). T2 showed more NDFDiv, CPDis, DMI, NDFI, DWG than T1, while T1 was higher than T2 in NDFDis (p < 0.05). The results obtained from in vitro, in situ and in vivo techniques indicate that the diet with 60% waste papaya silage (T2) showed a similar response to the control diet (T1). Therefore, waste papaya silage is a non-conventional feeding alternative for weaned calves in the Costa Chica region of the state of Guerrero, Mexico.

Hematological picture of pediatric Sudanese patients with visceral leishmaniasis and prediction of leishmania donovani parasite load.

Visceral leishmaniasis (VL) is a systemic protozoan infection caused by Leishmania donovani (L. donovani) and transmitted by sand flies, causing macrophage invasion in the liver, spleen, and bone marrow. Diagnosis of VL is currently based on clinical signs, symptoms, and specific in-vitro markers and bone marrow investigations. However, VL's specific hematological and bone marrow manifestation in Sudanese pediatric patients is not well studied. To examine the blood and bone marrow characteristics in pediatric patients from Sudan who have VL. This is a retrospective hospital-based study with a sample of 107 consecutive Sudanese pediatric patients. The data focused on hematological and bone marrow results. We included only the completed records of the pediatric patients with VL in the Tropical Disease Teaching Hospital in Khartoum, Sudan from the period of 2016 to 2020. The majority of pediatric patients included in this study are below 5-years-old (n = 59, 55.2%). Moreover, anemia, thrombocytopenia, and leukopenia were among the prevalent characteristics in the population under study. To further analyze the data, we developed a machine learning model using boosted forest algorithms to predict L. donovani parasites load, with a mean accuracy of 0.88 for the training dataset and an accuracy of 0.46, 0.50, and 0.74 for mild, moderate, and severe L. donovani parasite load in the validation dataset. This study shows that the most common bone marrow change among Sudanese VL children was increased chronic inflammatory cells (n = 88, 82.2%) with present macrophage hemophagocytes (n = 103, 96.3%). While anemia and thrombocytopenia were the most common hematological changes. These results will hopefully lead to an early diagnosis and hence better management for Sudanese pediatric patients with suspected VL.

Leishmania major surface components and DKK1 signalling via LRP6 promote migration and longevity of neutrophils in the infection site.

Host-related factors highly regulate the increased circulation of neutrophils during Leishmania infection. Platelet-derived Dickkopf-1 (DKK1) is established as a high-affinity ligand to LRP6. Recently, we demonstrated that DKK1 upregulates leukocyte-platelet aggregation, infiltration of neutrophils to the draining lymph node and Th2 differentiation during Leishmania infection, suggesting the potential involvement of the DKK1-LRP6 signalling pathway in neutrophil migration in infectious diseases. In this study, we further explored the potential role of DKK1-LRP6 signalling in the migration and longevity of activated neutrophils in the infection site using BALB/c mice with PMNs deficient in LRP6 (LRP6NKO) or BALB/c mice deficient in both PMN LRP6 and platelet DKK1 (LRP6NKO DKK1PKO). Relative to the infected wild-type BALB/c mice, reduced neutrophil activation at the infection site of LRP6NKO or LRP6NKO DKK1PKO mice was noted. The neutrophils obtained from either infected LRP6NKO or LRP6NKO DKK1PKO mice additionally showed a high level of apoptosis. Notably, the level of LRP6 expressing neutrophils was elevated in infected BALB/c mice. Relative to infected BALB/c mice, a significant reduction in parasite load was observed in both LRP6NKO and LRP6NKO DKK1PKO infected mice. Notably, DKK1 levels were comparable in the LRP6NKO and BALB/c mice in response to infection, indicating that PMN activation is the major pathway for DKK1 in promoting parasitemia. Parasite-specific components also play a crucial role in modulating neutrophil circulation in Leishmania disease. Thus, we further determine the contribution of Leishmania membrane components in the migration of neutrophils to the infection site using null mutants deficient in LPG synthesis (Δlpg1- ) or lacking all ether phospholipids (plasmalogens, LPG, and GIPLs) synthesis (Δads1- ). Relative to the WT controls, Δads1- parasite-infected mice showed a sustained decrease in neutrophils and neutrophil-platelet aggregates (for at least 14 days PI), while neutrophils returned to normal in Δlpg1- parasite-infected mice after day 3 PI. Our results suggest that DKK1 signalling and Leishmania pathogen-associated molecular patterns appear to regulate the migration and sustenance of viable activated neutrophils in the infection site resulting in chronic type 2 cell-mediated inflammation.

Short Term Treatment Monitoring of Renal and Inflammatory Biomarkers with Naturally Occurring Leishmaniosis: A Cohort Study of 30 Dogs

Various inflammatory and renal biomarkers have already been assessed for monitoring the response to anti-leishmanial therapy in canine leishmaniosis. This study assessed the parasite load, various inflammatory and renal biomarkers pre- and post-treatment, and any association between the studied variables and the degree of disease severity at diagnosis. This is a prospective cohort study of 30 client-owned dogs with leishmaniosis, classified according to LeishVet’s guidelines as stage I (n = 2), stage IIa (n = 7), stage IIb (n = 6), stage III (n = 8), and stage IV (n = 7). In addition to Leishmania real-time PCR in the bone marrow, blood and urine, previously studied biomarkers, and several inflammatory and renal markers never investigated in canine leishmaniosis, such as fibrinogen, antithrombin, urinary fractional excretion of sodium, and urinary amylase-to-creatinine ratio were measured pre- and post-treatment (meglumine antimoniate or miltefosine + allopurinol). A positive Leishmania real-time PCR in the blood at diagnosis predicted a positive Leishmania real-time PCR in the bone marrow post-treatment (p = 0.003). Following treatment, antithrombin and urinary amylase-to-creatinine ratio were significantly changed (p &lt; 0.001, respectively). Urinary amylase-to-creatinine ratio, total iron-binding capacity, and antithrombin were the variables most strongly associated with disease severity (p &lt; 0.005, respectively). Urinary amylase-to-creatinine ratio can be a useful marker to monitor treatment response and to classify the degree of disease severity.

Intranasal Trans-Sialidase Vaccine Mitigates Acute and Chronic Pathology in a Preclinical Oral Chagas Disease Model

Chagas disease, caused by Trypanosoma cruzi, leads to severe complications in 30% of infected individuals, including acute myocarditis and chronic fibrosing cardiomyopathy. Despite the significant burden of this disease, there is currently no licensed vaccine available to prevent it. This study aimed to evaluate the mucosal and systemic immunogenicity as well as the prophylactic efficacy of a mucosal vaccine candidate and its impact on both acute and chronic cardiomyopathy. The results showed that the nasal administration of trans-sialidase (TS) plus c-di-AMP (TS+A) vaccine elicited a NALT expression of IFN-γ, IL-17a and IL-4 mRNA as well as a nasal-specific production of IgA. An in vivo challenge with TS also triggered increased proliferation of lymphocytes from the NALT, sentinel cervical lymph node, and spleen. TS+A immunization increased the plasma levels of Th1/Th2/Th17 cytokines and elicited an evident cellular response by which to judge enhanced delayed-type hypersensitivity responses following a TS footpad challenge. After oral infection, TS+A-vaccinated mice showed significantly reduced parasitemia and parasite load in the heart, muscles and intestines, while markers of hepatic and muscle damage as well as clinical manifestations of acute infection were strongly diminished. TS+A also attenuated acute myocarditis and the expression of inflammatory markers in the heart. The protection conferred by TS+A extended into the chronic phase, where it resulted in a clear reduction in chronic myocarditis, fibrosis and functional electrocardiographic abnormalities, associated with a decreased expression of the pro-fibrotic TGF-β. These results revealed that it is possible to develop a mucosal vaccine against T. cruzi based on TS and c-di-AMP that is capable of reducing the development of Chagas cardiomyopathy, the hallmark of Chagas disease.

Evaluating CD1a Immunohistochemistry for Tegumentary Leishmaniasis Diagnosis in the New World: A Focus on Colombia.

Leishmaniasis, a chronic vector-borne disease caused by parasites of the genus Leishmania, presents diagnostic challenges. Conventional diagnostic methods struggle with accurate visualization of these parasites. Immunostaining with CD1a has demonstrated effectiveness in visualizing Leishmania parasites, particularly in the Old World. However, the application of CD1a immunostaining in Colombian leishmaniasis remains unexplored. To determine the utility of CD1a as an immunomarker in detecting chronic forms of tegumentary leishmaniasis. This proof-of-concept study involved 48 paraffin-embedded samples categorized into 3 groups: moderate-to-high parasite load (n = 15), low load (n = 15), and chronic granulomatous inflammation (n = 13); 5 samples diagnosed with cutaneous histoplasmosis. These samples were stained with the immunomarker CD1a clone EP3622 for comparative analysis. In addition, CD1a immunohistochemistry was compared with 18S rDNA qPCR and hematoxylin-eosin staining to evaluate its performance in relation to these established methods. CD1a immunohistochemistry was positive in 46.51% of the samples evaluated. This immunomarker showed lower sensitivity and negative predictive value than 18S rDNA qPCR and hematoxylin-eosin staining; specificity and negative predictive value were consistent. ROC indicated inferior discrimination for leishmaniasis compared with 18 s rDNA qPCR and hematoxylin-eosin staining. Immunohistochemistry for CD1a could be a diagnostic support in the detection of chronic forms of tegumentary leishmaniasis.

Dramatic recent declines in the size of monarch butterfly (Danaus plexippus) roosts during fall migration

The conservation status of monarch butterflies in North America is a topic of intense scrutiny and debate. It is clear that winter colonies in Mexico are declining, yet some recent studies suggest that summer breeding populations are relatively stable and similar to historical abundances. One possible explanation for these discordant patterns is that fall migration success has been recently disrupted. Here, we use a relatively unexplored citizen-scientist dataset on the size of monarch "roosts," which are resting aggregations on vegetation, to infer changes in monarch abundance along the fall migration route over the last 17 y. We found that the timing of migration remained relatively unchanged while the flyway has generally become warmer and greener. Warmer and greener conditions were associated with larger roosts, yet we found steady, dramatic declines in roost sizes through time that were independent of climate and landscape factors. Roost sizes have declined as much as 80%, with losses increasing from north to south along the migration route. These findings suggest that failure during the fall migration could explain the apparent drop in monarch numbers from summer breeding to overwintering populations. This in turn suggests that conservation efforts that support fall migration success are most needed, such as providing high quality nectar plants along the migration route or limiting the planting of nonnative milkweeds that enhance monarch parasite loads. Overall, it appears the fall migration of monarch butterflies is under imminent threat, even if the species' overall survival is not.

Trypanosoma cruzi-derived exovesicles contribute to parasite infection, tissue damage, and apoptotic cell death during ex vivo infection of human placental explants.

Trypanosoma cruzi, the causative agent of Chagas disease, can be congenitally transmitted by crossing the placental barrier. This study investigates the role of T. cruzi-derived exovesicles (TcEVs) in facilitating parasite infection and the consequent tissue damage and apoptotic cell death in human placental explants (HPEs). Our findings demonstrate that TcEVs significantly enhance the parasite load and induce tissue damage in HPEs, both in the presence and absence of the parasite. Through histopathological and immunohistochemical analyses, we show that TcEVs alone can disrupt the placental barrier, affecting the basal membrane and villous stroma. The induction of apoptotic cell death is evidenced by DNA fragmentation, caspase 8 and 3, and p18 fragment immunodetection. This damage is exacerbated when TcEVs are combined with T. cruzi infection. These findings suggest that TcEVs play a critical role in the pathogenesis of congenital Chagas disease by disrupting the placental barrier and facilitating parasite transmission to the fetus. This study provides new insights into the mechanisms of transplacental transmission of T. cruzi and highlights the potential of targeting TcEVs as a therapeutic strategy against congenital Chagas disease.

Can letrozole be repurposed for the treatment of visceral leishmaniasis?

Visceral leishmaniasis, caused by Leishmania infantum in New World countries, is the most serious and potentially fatal form of leishmaniasis, if left untreated. There are currently no effective prophylactic measures, and therapeutic options are limited. Therefore, we investigated whether the aromatase inhibitor letrozole (LET), which is already used to treat breast cancer, has an antileishmanial activity and/or immunomodulatory potential and therefore may be used to treat L. infantum infection. LET was active against L. infantum promastigote and amastigote life cycle stages in an in vitro infection model using human THP-1 cell-derived macrophages. In human peripheral blood leukocytes ex vivo, LET reduced the internalized forms of L. infantum by classical monocytes and activated neutrophils. Concomitantly, LET stimulated the production of IL-12/TNF-α and decreased the production of IL-10/TGF-β by peripheral blood phagocytes, while in T and B cells, it promoted the production of TNF-α/IFN-γ and decreased that of IL-10. In a murine infection model, LET significantly reduced the parasite load in the liver after just 5 days and in the spleen after 15 days. During in vivo treatment with LET, the production of TNF-α/IFN-γ also increased. In addition, the proportion of developing granulomas decreased and that of mature granulomas increased in the liver, while there was no significant change in organ architecture in the spleen. Based on these data, repositioning of LET may be promising for the treatment of visceral leishmaniasis in humans.

Compared Antileishmanial Activity of Clomiphene and Tamoxifen.

Drug repositioning is an efficient strategy to search for new treatment alternatives that is especially valuable for neglected parasitic diseases such as leishmaniasis. Tamoxifen and raloxifene are selective estrogen receptor modulators (SERMs) that have shown antileishmanial activity. Clomiphene is a SERM structurally similar to tamoxifen, whose antileishmanial potential is unknown. That is why the objective of the present work was to evaluate its antileishmanial activity in vitro and in vivo in comparison with tamoxifen. The inhibitory effect against promastigotes of L. amazonensis, L. major, and L. mexicana was evaluated for both compounds, as well as the cytotoxicity against mouse peritoneal macrophages, the growth inhibitory activity in intracellular amastigotes of L. mexicana, and the in vivo activity in mice experimentally infected with L. mexicana. Clomiphene was about twice as active as tamoxifen against both promastigotes and intracellular amastigotes, with IC50 values of 1.7-3.3 µM for clomiphene and 2.9-6.4 µM for tamoxifen against all three species of promastigotes and 2.8 ± 0.2 µM and 3.7 ± 0.3 µM, respectively, against L. mexicana amastigotes. Clomiphene structurally affected several parasite organelles in a concentration-dependent fashion, leading to the death of both promastigotes and intracellular amastigotes. Interestingly, the macrophage host cell did not appear damaged by any of the clomiphene concentrations tested. With oral administration at 20 mg/kg for 14 days, both compounds showed similar effects in terms of reducing the growth of the lesions, as well as the weight of the lesions and the parasite load at the end of the follow-up period. The results showed the potential of SERMs as antileishmanial drugs and support further testing of clomiphene and other compounds of this pharmacological group.

Differential Regulation of L-Arginine Metabolism through NOS2 and Arginases during Infection with Trypanosoma cruzi.

L-arginine metabolism through arginases and inducible nitric oxide synthase (NOS2) constitutes a fundamental axis for the resolution or progression of Chagas disease. Infection with Trypanosoma cruzi can cause a wide spectrum of disease, ranging from acute forms contained by the host immune response to chronic ones, such as the chronic chagasic cardiomyopathy. Here, we analyzed, in an in vitro model, the ability of two T. cruzi isolates, with different degrees of virulence, to regulate the metabolism of L-arginine through arginase 1 (Arg-1) and NOS2 in macrophages and through arginase 2 (Arg-2) and NOS2 in cardiomyocytes. Stimulation of bone marrow-derived macrophages (BMMΦ), obtained from CD1 mice, with TNF-α + IFN-γ induced their polarization into classically activated macrophages (CAMΦ), which expressed functional NOS2, while stimulation with IL-4 induced their polarization into alternatively activated macrophages (AAMΦ), which expressed functional Arg-1. Interestingly, stimulation of cardiomyocytes, obtained from hearts of CD1 neonatal mice, with TNF-α + IFN-γ or IL-4 also resulted in functional NOS2 and arginase expression, as observed in CAMΦ and AAMΦ, but Arg-2 was the arginase isoform expressed instead of Arg-1. We observed that infection of BMMΦ with the more virulent T. cruzi isolate (QRO) importantly diminished NOS2 expression and nitric oxide (NO) production in CAMΦ, allowing parasite survival, while infection with the less virulent isolate (CI2) did not diminish NOS2 activity and NO production in CAMΦ to a great extent, which resulted in parasite killing. Regarding Arg-1, infection of BMMΦ with the QRO isolate significantly induced Arg-1 expression and activity in AAMΦ, which resulted in a higher parasite load than the one in the unstimulated BMMΦ. Even though infection with CI2 isolate did not increase Arg-1 expression and activity in AAMΦ, the parasite load was higher than the one in the unstimulated BMMΦ but at a lesser magnitude than that observed during infection with the QRO isolate. On the other hand, infection of cardiomyocytes with either QRO or CI2 isolates and further stimulation with TNF-α + IFN-γ inhibited NOS2 expression and NO production, leading to amelioration of infection. Surprisingly, infection of cardiomyocytes with either QRO or CI2 isolates and further stimulation with IL-4 strongly inhibited Arg-2 expression and function, which resulted in parasite loads similar to those observed in unstimulated cardiomyocytes. Our results suggest that T. cruzi isolates that exhibit variable virulence or pathogenicity degrees differentially regulate L-arginine metabolism through Arg-1/2 and NOS2 in macrophages and cardiomyocytes.

Toxoplasma qPCR kinetics to guide pre-emptive treatment of toxoplasmosis after allogeneic hematopoietic stem cell transplantation.

Recent ECIL-guidelines recommend a quantitative PCR (qPCR) guided pre-emptive treatment approach to toxoplasmosis in seropositive recipients of allogeneic hematopoietic cell transplantation (allo-HCT). While qPCR might serve as a sensitive tool for early Toxoplasma detection, its role in treatment follow-up remains unknown. We analyzed the qPCR kinetics of allo-HCT recipients experiencing either Toxoplasma infection (TI, n=71) or disease (TD, n=14) in relation to different parameters. We included 85 patients with available qPCR values expressed as quantitative cycle (Cq) from four large hematological centers from 2009 to 2023, and kinetic analysis was performed in a selection of 74 patients screened at least weekly with blood qPCR. Day 0 (D0) was the day of anti-Toxoplasma treatment start or (when untreated) day of diagnosis. Time to qPCR negativity was inversely proportional to the Cq value at D0 (p=0.0063). Not reaching negativity at D10 was associated with a significantly higher mortality at D30 (p=0.023). Patients with a high D0-parasitic load and patients with TD showed slower clearance (p<0.001, p=0.032). Time to negativity was not significantly different for patients started on prophylactic vs curative doses as first-line treatment regimen (p=0.16). This study underscores the predictive value of qPCR kinetics monitoring in allo-HCT patients with toxoplasmosis. With the aforementioned risk factors, clinicians can identify patients at high-risk for worse outcome. Our results support to consider a therapeutic change or reinforcement if the parasitic load does not decrease after 10 days, supplementing existing clinical guidelines.