Prepatent Period Research Articles

Intestinal Parasitic Infections of Stray Dogs on the Caribbean Island of St. Maarten/St. Martin

Abstract The island of St. Maarten/St. Martin has a big stray dog population, with many roaming and non-sterilised owned dogs. Faecal samples from 111 dogs, including 70 puppies and 41 adult dogs, underwent coprological examination including flotation. Collection occurred from July through September of 2022. The infection rate of 92.8 % was higher than that reported in the previous Caribbean studies. The species found were Cystoisospora spp., Giardia intestinalis, species from the family Ancylostomatidae, Toxocara canis, Trichuris vulpis, and Dipylidium caninum. Ancylostomatidae family had the highest prevalence at 75.7 %. The high T. canis (42.3 %) and D. caninum (13.5 %) rates were attributed to the young age of the sample population in this study. Conversely, the low T. vulpis (10 %) rate was attributed to its long prepatency period, as eggs only shed from older puppies and dogs. Cystoisospora spp. were the most prevalent protozoan parasite at 10.8 %. The total coinfection rate was 45.9 %, with the most being 5 different species. It was determined that the parasite burden on the island is high and is likely to benefit from animal welfare interventions.

Molecular identification and biological characterization of Eimeria columbarum from domestic pigeons (Columba livia domestica) in Guangdong, China

Pigeon coccidiosis caused by Eimeria spp. is an important veterinary disease with a significant economic impact on the pigeon industry. Preventive measures for Eimeria columbarum in pigeons have been hampered by the lack of extensive genetic, morphological, and biological data on the oocysts. In this study, we examined the prevalence and identity of Eimeria spp. in domestic pigeons from seven cities in Guangdong Province, China. Data show that coccidiosis was prevalent in domestic pigeons in Guangdong Province, with an overall Eimeria spp. detection rate of 73.4%. Five Eimeria species were identified, including E. columbarum (73.4%), Eimeria kapotei (25.6%), Eimeria labbeana (19.6%), Eimeria duculai (19.6%), and Eimeria tropicalis (6.7%). We obtained single oocyst-derived lines of the dominant E. columbarum from fecal specimens. E. columbarum oocysts measured 20.06 ± 0.69 μm × 18.63 ± 1.03 μm, and sporocysts measured 10.29 ± 0.82 μm × 85.38 ± 0.46 μm. In infection experiment using obtained E. columbarum isolates, 60-day-old coccidia-free pigeons exhibited a prepatent period of 105 h and patent period of 9–10 days followed by severe diarrhea, depression, anorexia, and emaciation. Endogenous development of the parasite was observed mainly in the cytoplasm of epithelial cells in the duodenum, jejunum, ileum, and rectum. Two generations of meronts developed on days 3 and 4 after infection, respectively, while gamont and gamete developed on day 5 after infection. The morphological, genetic, and biological data are expected to be useful in elucidating the biological characterization of pigeon coccidiosis to develop measures against the treatment and containment of this disease.

CALCIUM CHANGES IN Bulimulus tenuissimus (MOLLUSCA) EXPERIMENTALLY INFECTED WITH LARVAL Angiostrongylus cantonensis (NEMATODA)

Only in 2018 Bulimulus tenuissimus was incriminated as an intermediate host of Angiostrongylus cantonensis, the causative agent of infections in domestic, wild animals and humans, causing neural angiostrongyliasis or eosinophilic meningitis in humans. The present study aimed to infect the mollusk B. tenuissimus, using L1 larvae of A. cantonensis, under laboratory conditions, and to analyse the changes that occurred in the calcium metabolism of the host mollusk. The infection caused hypercalcification in the shell of B. tenuissimus infected with A. cantonensis, with a 242% increase in the concentration of CaCO3, at the end of the prepatent period, in the shells of infected mollusks and hypercalcemia, especially at the end of the third week of infection (+18.51%) in relation to the control group. The interference of the parasitic nematode in the calcium metabolism of the host mollusk was evidenced, with reductions in tissue deposits and elevation of calcemia and calcium content in the shell.

Evaluation of the Effects of Papain on Schistosoma mansoni: Miracidial Infection Capacity, Infection Prevalence, Cercarial Shedding and Molecular Changes in Biomphalaria alexandrina

PurposeThe aim of the present study is to assess the molluscicidal, larvicidal and genotoxicological activities of papain and how it can affect the host-parasite interactions.MethodsToxicity of papain on snails by making series of concentrations to calculate LC50, and then study its larvicide effect on the free larval stages of S. mansoni and infection rate of snails.ResultsPapain has a molluscicidal activity on adult snails of Biomphalaria alexandrina with a lethal concentration LC50 equals to 43.1 mg/L. In addition, it has activity on miracidia with half Lethal time (LT50) of 16.11 min., and on cercariae with 12.1 min. compared to control ones. The sub lethal concentration LC10 and LC25 (6.9 or 24.1 mg/L, respectively) decreased the survival rate of snails at the first cercarial shedding, the rate of infection, the average total number of cercariae per snail, the shedding period and the life span of snails, while the prepatent period was significantly increased than the control ones. The morphological alterations in cercariae after exposure to papain were occurred where the cercariae lacked motility and some had a dark tail with complete detachment of head and tail. Compared to the control group, the levels of cytochrome oxidase subunit I (COI) and (ND1) genes significantly decreased in snails after exposure to papain.ConclusionsPapain could be used as a potential molluscicide for elimination of schistosomiasis and decrease its transmission and deterioration of host-parasite interaction.

Sporocysts of Sarcocystis bertrami (syn. Sarcocystis fayeri) shed by dogs: Molecular analysis, morphometry and pattern of excretion

Sarcocystis bertrami (synonym: Sarcocystis fayeri) is a coccidian parasite that infects horses and donkeys in several countries. Dogs are known as definitive hosts of the parasite, however, the patent period is not well defined, and S. bertrami shed by dogs has never been confirmed by molecular methods. Here we investigated the shedding of S. bertrami by experimentally infected dogs and examined the excreted parasites by morphological and molecular tools. Three dogs of small breeds (one Yorkshire terrier and two miniature Pinschers) were acquired with ages of 30 and 60 days and were exclusively fed commercial dog food. Two dogs consumed equine muscle tissues containing cysts of S. bertrami. The third dog served as negative control and was simultaneously fed commercial dog food. The two animals that received equine tissues shed sporocysts and/or oocysts in their feces after prepatent periods of 13 and 23 days. The patent periods were 47 and 14 days. Sporocysts showed average dimensions of 14.19 µm (± 0.53) x 10.06 µm (± 0.44). The control dog did not shed sporocysts or oocysts of the parasite. Interestingly, patent periods had never been reported, and for one dog, the patent period (47 days) was longer than that reported for other Sarcocystidae parasites. PCRs to the gene 18S and to the internal transcribed spacer 1 (ITS1) of the rDNA were successfully performed with DNA extracted from sporocysts. ITS1 sequences were also obtained from the equine tissue cysts used to infect the dogs. Nucleotide sequences of cloned fragments of 18S from sporocysts, and ITS1 from both stages (tissue cysts and sporocysts) matched with S. bertrami (18S: 97.50–99.88 %; ITS1: 88.76–95.21 %), although high molecular diversity was observed with data from these loci. PCR to cox1 using sporocysts’ DNA failed to amplify any product. The possibility of the existence of an additional and undescribed Sarcocystis species in the excreted sporocysts, besides S. bertrami, cannot be excluded from this experiment. To our knowledge, this is the first molecular confirmation of S. bertrami in canine feces. Sporocyst dimensions and prepatent periods observed in this study were similar to those previously described for S. bertrami and S. fayeri. In conclusion, the molecular, morphological and biological data generated here fit in previous descriptions for both S. bertrami and S. fayeri.

First experimental observation on biology of the avian malaria parasite Plasmodium (Novyella) homonucleophilum (lineage pSW2), with remarks on virulence and distribution

Species of subgenus Novyella remain most fragmentarily studied amongst avian malaria agents. Transmission of the recently described Plasmodium (Novyella) homonucleophilum (lineage pSW2) occurs broadly in the Old World, including Europe, however biology of this pathogen remains insufficiently investigated. This study provided the first data on the development of P. homonucleophilum in the experimentally infected Eurasian siskins Spinus spinus exposed by inoculation of infected blood. The parasite strain was isolated from a naturally infected song thrush Turdus philomelos, multiplied in vivo, and inoculated to six Eurasian siskins. The same number of birds were used as negative controls. All exposed birds were susceptible, and the controls remained uninfected during the entire study (172 days). Prepatent period was 8–12 days post exposure (dpe). Maximum parasitaemia reached 50–90 % of infected erythrocytes between 20 and 44 dpe. Then, parasitaemia decreased but remained relatively high during the entire observation. Three of six exposed birds died, indicating high virulence of this infection. The parasitaemia increase coincided with a decline of haematocrit value, indicating anaemia. Polychromasia was evident in all infected birds but not in controls. Body mass of exposed birds increased, coinciding with increased food intake. The latter probably is an adaptation to compensate energy loss of hosts due to the long-lasting parasitism. Exo-erythrocytic stages were not found, suggesting that long-lasting parasitaemia was entirely due to erythrocytic merogony. The lineage pSW2 has been reported broadly in the Old World and is likely a generalist infection. Neglected avian Novyella malaria parasites are worth more attention of researchers due to their cosmopolitan distribution and high virulence.

Biological characteristics of a precocious line of Eimeria tenella.

The Eimeria tenella Yulin strain (EtYL), which is sensitive to most anti-coccidial drugs, was isolated in the Yulin area of Guangxi, China. Then, Eimeria tenella Yulin precocious line (pEtYL), a precocious line with a prepatent period of 108h, was obtained through early selection. The biological characteristics of pEtYL, including its morphology, purity, oocyst excretion curve, reproductive capacity, pathogenicity, immunogenicity, and preservation time, were comprehensively analyzed. The results showed that the isolated precocious line of E. tenella exhibited high purity, relatively weak pathogenicity, and good immunogenicity and can be used as a live vaccine line for chicken coccidiosis.

Impact of Schistosoma sp., Infection on Biological, Feeding, Physiological, Histological, and Genotoxicological Aspects of Biomphalaria alexandrina andBulinus truncatus Snails.

Trematode infections of the genus Schistosoma can induce physiological and behavioral changes in intermediate snail hosts. This is because the parasite consumes essential resources necessary for the host's survival, prompting hosts to adapt their behavior to maintain some level of fitness before parasite-induced mortality occurs. In this study, the reproductive and biochemical parameters of Biomphalaria alexandrina and Bulinus truncatus were examined during the cercareal shedding stage of infection with Schistosoma mansoni and Schistosoma haematobium, respectively, compared with controls. The study revealed an infection rate of 34.7% for S. mansoni and 30.4% for S. haematobium. In B. alexandrina infected with S. mansoni, a survival rate of 65.2% was recorded, along with a mean prepatent period of 30.3 ± 1.41days, a mean shedding duration of 14.2 ± 0.16days, and a mean lifespan of 44.1 ± 0.24days. Meanwhile, in B. truncatus infected with S. haematobium, a survival rate of 56.4% was observed, with a mean prepatent period of 44.3 ± 1.41days, a mean shedding duration of 22.6 ± 2.7days, and a mean lifespan of 66.9 ± 1.6days. Feeding increased in both infected species of snails, while the net reproductive rate (Ro) of the infected snails decreased. Total antioxidant (TAO) and lipid peroxidation activity increased in the two infected snail species during shedding, while Glutathione-S-transferase levels decreased. Lipid peroxidase activity and nitrogen oxide levels significantly decreased in infected B. alexandrina and increased in infected Bulinus. Steroid hormone levels were elevated in infected Biomphalaria, whereas they were reduced in infected Bulinus. Comet assay parameters showed an increase in the two infected genera after infection compared to control snails, indicating genotoxic damage and histopathological damage was observed. These findings demonstrate that infection with larva species diverse biochemical, hormonal, genotoxic, and histopathological changes in the tissues responsible for fecundity and reproduction in B. alexandrina and B. truncates comparing with controls.

Transcriptional Profiling of the Rabbit Liver Infected With Eimeria stiedae Reveals Dynamic Host Cell Responses During the Induction and Resolution of Cholangitis

Eimeria stiedae is one of the few eukaryotic pathogens that exclusively infect the liver and serves as a good model to study the host–pathogen interactions in this vital organ. In this study, we show that rabbits infected with E. stiedae develop severe but self‐healing cholangitis. RNA‐seq analysis of the liver gene expression landscapes over the long course of E. stiedae infection identified 912 differentially expressed genes (DEGs) in the prepatent period (794 up‐ and 118 downregulated genes), 2889 DEGs in the early oocyst shedding period (1870 up‐ and 1019 downregulated genes), 2859 DEGs in the peak oocyst shedding period (1923 up‐ and 936 downregulated genes), and 327 DEGs in the recovery period (164 up‐ and 163 downregulated genes). Combined with pathological observations, we identified dynamic changes in host–parasite interactions involving multiple pathways. They showed that E. stiedae infection induced full‐blown inflammatory, Th1 and Th17 immune responses at all time points. This was associated with the strong innate immune responses during the prepatent period, including increased Toll‐like and NOD‐like receptor signaling. Despite mounting several damage control and repair responses, such as PI3K‐Akt signaling, Ras signaling, and extracellular matrix‐receptor interactions, the liver underwent severe metabolic dysfunction, oxidative damage, and coagulopathy after patency and at peak infection, possibly as a result of suppressed peroxisome activities and downregulated PPAR signaling. These responses largely disappeared during late infection, suggesting that the liver self‐heals after severe cholangitis. These data provide new insights into host–pathogen interactions during Eimeria infection and improve our understanding of the pathogenesis of parasitic cholangitis.

Self-cure of Trypanosoma brucei brucei infection in West African Dwarf sheep

This study investigated the natural course of parasitaemia in West African Dwarf (WAD) sheep experimentally infected with Trypanosoma brucei brucei parasites and the potential for spontaneous regression without any therapeutic intervention. Ten (10) adult West African Dwarf sheep of both sexes were assigned to two groups of five sheep each. One of the groups was inoculated with approximately 1× 106 trypanosome parasites per animal, intravenously, while the second group served as uninfected control. Blood samples were collected daily until parasitaemia was established and for 7 days post establishment of parasitaemia and thereafter weekly till the end of the experiment in order to monitor the course of parasitaemia. The clinical signs, packed cell volume (PCV) and rectal body temperature were monitored. A pre-patent period of 28 days was observed with peak mean parasitaemia of 81.60 ± 27.71 million trypanosome parasites, on day 43 post inoculation. The parasitaemia declined in 60 % of the sheep from day 141 post-infection (PI) and reduced to 0.34±0.02. Clinical signs observed include weakness, mild anorexia and pale mucous membranes. The 40 % of animals that manifested clinical signs eventually died and their postmortem findings were indicative of severe anaemia and dehydration. Monitoring the sheep which recovered (for parasitaemia and clinical signs) up to 141 days PI showed there was no relapse. The Trypanosoma b. brucei infected WAD sheep used in the study were able to contain both parasitaemia and fever and recovered from the infection.

A NEW EIMERIA SPECIES (APICOMPLEXA: EIMERIIDAE) PARASITIZING COMMERCIAL CHUKAR PARTRIDGES (ALECTORIS CHUKAR) IN SOUTHERN ONTARIO.

A commercial producer hatching and rearing chukar partridges (Alectoris chukar) in Ontario, Canada had flocks experiencing coccidiosis. Microscopic analysis of Eimeria species isolated from a field sample indicated the presence of 2 distinct oocyst morphotypes; the most abundant species was determined to be Eimeria chapmani, based on oocyst morphology and sequence-based genotyping, and the less abundant, second Eimeria sp. was an undescribed parasite. Oocysts of the unknown Eimeria sp. were large and oval-shaped; dimensions averaged 27.9 μm by 17.0 μm (shape index = 1.65 μm). Oocysts contained at least 1 polar granule and 4 almond-shaped sporocysts with average dimensions measuring 12.5 μm by 6.9 μm (shape index = 1.83). Each sporocyst featured a Stieda body, sub-Stieda body, and sporocyst residuum; a sporocyst contained 2 sporozoites that each possessed a small anterior refractile body and a larger posterior refractile body. Virtually all oocysts sporulated after 24 hr when suspended in potassium dichromate at room temperature (22 C) on a rotary platform. Experimental infections with various doses of oocysts demonstrated elevated parasite shedding from birds gavaged with higher challenge doses; fecundity generally decreased in heavier infections. The approximate prepatent period of the parasite was 4-5 days (unsporulated oocysts observed histologically at 90 hr postinfection and in feces by day 5) and patency lasted until day 12 postinfection. To characterize the endogenous development of the Eimeria sp., tissues were collected at 8 regions along the intestinal tract (including the ceca and rectum) every 6 hr throughout the estimated prepatent period. Parasites were observed to infect the descending and ascending duodenum, midjejunum, proximal and distal ileum, and the ceca. The endogenous stages identified included intracellular sporozoites, 3 generations of merogony, and gametogonic stages. Sequences of the mitochondrial genome (GenBank MW934555) and nuclear 18S ribosomal DNA (GenBank MW934259) were obtained using polymerase chain reaction amplification for Sanger sequencing, and these were unique from all published sequences on GenBank. Molecular data, in conjunction with the unique biology of the Eimeria sp. isolated from the chukar partridge flock, support that this coccidium is new to science.

Parasitological and molecular characterization of Trypanosoma cruzi of triatomines and mammals from endemic areas for Chagas disease in Venezuela.

It is estimated that 6-7 million people worldwide are infected with Trypanosoma cruzi, the parasite that causes Chagas disease. In Venezuela, Chagas disease remains a public health problem. In this work, T. cruzi isolates from six species of triatomines and mammals of the orders Didelphimorphia and Xenarthra, captured in rural communities of Monagas, underwent parasitological and molecular characterization. A total of 471 triatomines and 17 mammals were captured, with a natural infection rate of 41.4% and 70.6%, respectively. In the male NMRI mouse model used for parasitological characterization (prepatent period, parasitemia curve, mouse mortality, and tissular parasitism), T. cruzi isolates exhibited high lethality due to their pronounced virulence, irrespective of the parasite load in each mouse, resulting in a mortality rate of 75%. Among the vector isolates, in the mouse model, only 2 out of 6 remained alive, while the rest perished during the evaluation. Conversely, the isolates from mammals proved fatal for all the inoculated mice. All isolates were identified as belonging to DTU TcI, based on the molecular markers such as the intergenic region of the miniexon, D7 divergent domain of the 24Sα rDNA, size-variable domain of the 18S rDNA, and hsp60-PCR-RFLP-EcoRV. This study demonstrates the presence of vectors and mammalian reservoirs naturally infected with T. cruzi in communities of Monagas, the 9th largest and 9th most populous state in Venezuela. This situation represents a neglected epidemiological problem demanding urgent attention and imperative health care intervention.

1H-NMR based-metabolomics reveals alterations in the metabolite profiles of chickens infected with ascarids and concurrent histomonosis infection

BackgroundGut infections of chickens caused by Ascaridia galli and Heterakis gallinarum are associated with impaired host performance, particularly in high-performing genotypes. Heterakis gallinarum is also a vector of Histomonas meleagridis that is often co-involved with ascarid infections. Here, we provide a first insight into the alteration of the chicken plasma and liver metabolome as a result of gastrointestinal nematode infections with concomitant histomonosis. 1H nuclear magnetic resonance (1H-NMR) based-metabolomics coupled with a bioinformatics analysis was applied to explore the variation in the metabolite profiles of the liver (N = 105) and plasma samples from chickens (N = 108) experimentally infected with A. galli and H. gallinarum (+H. meleagridis). This was compared with uninfected chickens at different weeks post-infection (wpi 2, 4, 6, 10, 14, 18) representing different developmental stages of the worms.ResultsA total of 31 and 54 metabolites were quantified in plasma and aqueous liver extracts, respectively. Statistical analysis showed no significant differences (P > 0.05) in any of the 54 identified liver metabolites between infected and uninfected hens. In contrast, 20 plasma metabolites including, amino acids, sugars, and organic acids showed significantly elevated concentrations in the infected hens (P < 0.05). Alterations of plasma metabolites occurred particularly in wpi 2, 6 and 10, covering the pre-patent period of worm infections. Plasma metabolites with the highest variation at these time points included glutamate, succinate, trimethylamine-N-oxide, myo-inositol, and acetate. Differential pathway analysis suggested that infection induced changes in (1) phenylalanine, tyrosine, and tryptophan metabolism, (2) alanine, aspartate and glutamate metabolism; and 3) arginine and proline metabolism (Pathway impact > 0.1 with FDR adjusted P-value < 0.05).ConclusionIn conclusion, 1H-NMR based-metabolomics revealed significant alterations in the plasma metabolome of high performing chickens infected with gut pathogens—A. galli and H. gallinarum. The alterations suggested upregulation of key metabolic pathways mainly during the patency of infections. This approach extends our understanding of host interactions with gastrointestinal nematodes at the metabolic level.

Serum biochemical parameters of Yankasa sheep experimentally infected with &lt;i&gt;Trypanosoma evansi&lt;/i&gt; and treated with diminazene aceturate (Berenil®)

Blood glucose, serum total protein, and liver transaminases were determined in Yankasa sheep experimentally infected with Trypanosoma evansi (T. evansi) and treated with diminazene aceturate (Berenil® ). A total of 30 animals were divided into 6 groups (A to F) (n=5). Animals from each group were either uninfected or infected with T. evansi and treated with Berenil® . Infection of the infected groups (A, C and E) was done via intravenous inoculation of T. evansi, while the infected group C and E were treated with Berenil® at 3.5 and 7 mg/kg BW (single dose), respectively, by day 16 post-infection (PI). The infected groups had a pre-patent period of 8 days, with similar levels of parasitaemia of 4.7 ± 0.27. In group A, the mean parasite count rose significantly (p &lt; 0.05) to 72.8 ± 1.07 by day 12 PI and continued to a peak value of 250.6 ± 1.98 by day 28 PI. In groups C and E, the initial parasitaemia rose significantly (p &lt; 0.05) to a peak count of 80.8 ± 1.12 and 78.2 ± 1.11 by day 12 PI, following treatment with 3.5 and 7.0 mg/kg BW of Berenil® , by day 20 PI, respectively, and was completely eliminated by day 9 and 5 post-treatment (PT), respectively. The biochemical analysis showed that, from day 8 PI, the infected sheep experienced significant (p &lt; 0.05) increases in alkaline phosphatase, aspartate and alanine aminotransferase, creatinine and urea; with decreases in blood glucose and total protein. However, these changes reverted to their pre-infection values, by day 28 PI in all the affected animals following treatment with both doses of Berenil® . It is therefore, concluded that the two doses of Berenil® (3.5 mg/kg and 7.0 mg/kg) were effective in the treatment of the disease but 7.0 mg/kg cleared the parasitaemia faster.

A fecal egg count reduction test in grazing beef steers using topical pioneer and generic eprinomectin and fenbendazole oral suspension.

Many generic anthelmintics are commercially available; however, little information exists regarding product effectiveness compared to pioneer brands. The objective of this study was to compare the effectiveness of a generic eprinomectin to the pioneer eprinomectin, as well as to fenbendazole and fenbendazole in combination with the pioneer eprinomectin in grazing beef steers via a fecal egg count reduction test. Forty naturally infected steers were allocated into five treatment groups based on ranked fecal egg counts: 1. pioneer eprinomectin (Eprinex®, topical), 2. generic eprinomectin (Eprizero®, topical), 3. fenbendazole (Safeguard® 0.5% oral suspension), 4. combination of pioneer eprinomectin topical and fenbendazole oral suspension, 5. negative control. Fecal samples were collected on days -14, 0, 14, and 29. Data were analyzed using the MIXED procedure of SAS 9.4. Neither the pioneer nor the generic eprinomectin groups reached a 90% fecal egg count reduction (FECR) throughout the study with reductions of 50% and 11% for pioneer eprinomectin and 79% and-5% for generic eprinomectin at days 14 and 29 post-treatment, respectively. Both the fenbendazole and combination groups showed 98% and 99% FECR, respectively, at 14days post-treatment; these reductions dropped slightly at day 29 post-treatment to 94% and 89%, respectively. Primarily Cooperia punctata, Cooperia oncophora and Ostertagia ostertagi larvae were recovered from the coprocultures across all treatment groups. Interestingly, the proportions of C. punctata and C. oncophora essentially demonstrated a post-treatment reversal in the both the fenbendazole and combination treatment groups when comparing days 0 and 29, demonstrating prepatency period differences or a fenbendazole treatment effect.

Effect of time of treatment on the efficacy of trypanocides in rats experimentally infected with Trypanosoma brucei brucei

The effect of treatment time on the efficacy of trypanocides in rats experimentally infected with Trypanosoma brucei brucei was assessed. The thirty albino rats utilized in this study were divided into six groups, each with five rats. Group 1 rats were uninfected while those in groups 2 - 6 were inoculated intraperitoneally with 106 trypanosomes. Group 2 rats were left untreated while groups 3 - 6 rats were treated respectively on days 5, 8, 11 and 14 post infection (PI) with 1.0 mg/kg Securidium® (brand of isometamidium chloride) intraperitoneally. Level of parasitaemia, rectal temperature, clinical signs, haematological indices (packed cell volume and total leucocyte count) and survivability were used to evaluate the treatment time on the efficacy of Securidium®. Pre-patent period was 4 - 5 days. On days 4, 5, and 11 following the treatments (PT), the parasites were eliminated in the treated groups 3 - 6 respectively. Also, two rats relapsed in group 3 from 37 days PT with 20% mortality, whereas groups 4 - 6 rats relapsed from days 19, 16 and 21 PT respectively. Groups 4 - 6 rats had 40%, 60% and 80% mortalities respectively. The mean PCV and TLC showed a striking drop (p&lt;0.05) PI, however, group 3 had a better result PT compared to other infected-treated groups. In conclusion, it is safe to say that treatment time is a significant determinant of therapeutic efficacy in trypanosomosis, as early treatment group had better overall indices of therapeutic efficacy than the late treatment groups.

Pre-vaccination monocyte-to-lymphocyte ratio as a biomarker for the efficacy of malaria candidate vaccines: A subgroup analysis of pooled clinical trial data.

Pre-vaccination monocyte-to-lymphocyte ratio was previously suggested as a marker for malaria vaccine effectiveness. We investigated the potential of this cell ratio as a marker for malaria vaccine efficacy and effectiveness. Effectiveness was investigated by using clinical malaria endpoint, and efficacy was investigated by using surrogate endpoints of Plasmodium falciparum prepatent period, parasite density, and multiplication rates in a controlled human malaria infection trial (CHMI). We evaluated the correlation between monocyte-to-lymphocyte ratio and RTS,S vaccine effectiveness using Cox regression modeling with clinical malaria as the primary endpoint. Of the 1704 participants in the RTS,S field trial, data on monocyte-to-lymphocyte ratio was available for 842 participants, of whom our analyses were restricted. We further used Spearman Correlations and Cox regression modeling to evaluate the correlation between monocyte-to-lymphocyte ratio and Whole Sporozoite malaria vaccine efficacy using the surrogate endpoints. Of the 97 participants in the controlled human malaria infection vaccine trials, hematology and parasitology information were available for 82 participants, of whom our analyses were restricted. The unadjusted efficacy of RTS,S malaria vaccine was 54% (95% CI: 37%-66%, p <0.001). No correlation was observed between monocyte-to-lymphocyte ratio and RTS,S vaccine efficacy (Hazard Rate (HR):0.90, 95%CI:0.45-1.80; p = 0.77). The unadjusted efficacy of Whole Sporozoite malaria vaccine in the appended dataset was 17.6% (95%CI:10%-28.5%, p<0.001). No association between monocyte-to-lymphocyte ratio and the Whole Sporozoite malaria vaccine was found against either the prepatent period (HR = 1.16; 95%CI:0.51-2.62, p = 0.72), parasite density (rho = 0.004, p = 0.97) or multiplication rates (rho = 0.031, p = 0.80). Monocyte-to-lymphocyte ratio alone may not be an adequate marker for malaria vaccine efficacy. Further investigations on immune correlates and underlying mechanisms of immune protection against malaria could provide a clearer explanation of the differences between those protected in comparison with those not protected against malaria by vaccination.

Comparative pathogenicity of single and mixed drug-resistant Trypanosoma brucei brucei and Trypanosoma congolense infections in rats

Drug-resistant trypanosomes are widespread in sub-Saharan Africa and in conjunction with the drug-sensitive phenotypes cause a serious endemic wasting disease in animals. We evaluated the pathogenicity of single and mixed drug-resistant Trypanosoma brucei brucei and T. congolense isolates in 35 female rats, randomly divided into seven groups (1–7) of five rats. Group 1 was the uninfected control. Groups 2 and 3 were infected with drug-sensitive T. brucei brucei and T. congolense, respectively, whereas groups 4 and 5 were infected with multidrug-resistant T. brucei brucei and T. congolense respectively. Group 6 were infected with drug-sensitive T. brucei brucei and T. congolense while group 7 were infected with multidrug-resistant T. brucei brucei and T. congolense. Parasitaemia kinetics, haematological parameters, body weight, clinical signs, survival time, gross and histopathological changes in the spleen were evaluated. Parasitaemia occurred between day 3–9 post-infection in all the infected groups. Rats in groups 4 and 7 had markedly prolonged (p < 0.05) pre-patent period, days to first peak parasitaemia, survival time, and lower (p < 0.05) parasitaemia level than groups 2 and 6 rats while these parameters were comparable for groups 3 and 5 rats. Anaemia was noted in the infected groups but the severity did not vary amongst the infected groups. Severe clinical signs and splenic lesions were noted in rats infected with drug-sensitive trypanosome species compared to the multidrug-resistant species. Therefore, we conclude that the trypanosome isolates were pathogenic. However, the drug-sensitive T. brucei brucei and mixed drug-sensitive trypanosome infections were more pathogenic than their multidrug-resistant counterparts.

EPIDEMIOLOGICAL AND CLINICAL IMPORTANCE OF CANINE DIOCTOPHIMOSIS

Dioctophimosis is an endoparasitism in dogs caused by Dioctophyma renale, a nematode with an indirect life cycle and high zoonotic potential. Infection in dogs occurs through ingestion of transitional/paratenic hosts containing infective larvae. The preferred site of parasitism is the right kidney, although the parasite may also be ectopically localized in subcutaneous tissue, internal organs, peritoneum, and mediastinum. Since dogs are usually infected with a small number of parasites, the disease is asymptomatic, making the diagnosis of this disease in clinical veterinary practice rather difficult. In addition, as dogs are usually infected with a small number of parasites, the disease is asymptomatic, which makes the diagnosing of this disease in clinical veterinary practice difficult. The long prepatent period, lasting three to five months, makes it impossible to diagnose the disease in dogs younger than six months. Clinical suspicion of dioctophimosis in dogs is established on the basis of anamnestic/epizootiologic data and the clinical picture, while the final diagnosis is made ante mortem or post mortem on the basis of reliable diagnostic parameters and methods. The most practical application in routine diagnosis of canine dioctophimosis is the detection of D. renale eggs in urine sediment. When dioctophimosis is suspected in carnivores, the differential diagnosis should exclude urinary capillariosis, feline polycystic nephropathy, leptospirosis, renal fibrosis, and nephritis of various etiology. The outcome of treatment is uncertain and includes surgical removal of the affected kidney or drug therapy with avermectin derivatives. Prophylaxis consists of preventing contact of dogs with potential transitional hosts and controlling the feeding of their heat-untreated meat. Because of the potential risks that D. renale may have on the health of dog owners, education on the etiopathogenesis and means of occurrence, maintenance, and spread of this nematode is necessary.

Overexpression of Eimeria tenella Rhoptry Kinase 2 Induces Early Production of Schizonts.

Eimeria tenella is an obligate intracellular parasite responsible for avian coccidiosis. Like other apicomplexan parasites, such as Toxoplasma gondii, cell invasion and intracellular development rely on apical organelle content discharge, named micronemes and rhoptries. Some rhoptry (ROP) kinases (ROPK) are key virulence factors in T. gondii. To date, among the 28 ropk genes carried by E. tenella, only two to four were confirmed by proteomic analysis or immunostaining to be expressed at the sporozoite stage. We have previously shown that EtROP1 is implicated in the inhibition of host cell apoptosis by interacting with the cellular p53. This work functionally described the second ROP kinase expressed at the sporozoite stage in E. tenella. EtROP2 is an active kinase that phosphorylates cell substrates of approximately 50 kDa. Its overexpression leads to the shortening of the prepatent period and to the early development of first-generation schizonts. Conduction of RNA sequencing analysis and reverse transcriptase quantitative PCR (RT-qPCR) on the host cell allowed us to identify the mitogen-activated protein kinase (MAPK) pathway and the transcription factor cFos to be upregulated by EtROP2. We also showed by immunofluorescence assay that the active kinase EtROP2 is implicated in the p38 MAPK pathway activation. We established here that EtROP2 activates the p38 MAPK pathway through a direct or indirect phosphorylation, leading to the overexpression of the master transcription factor cFos known to be implicated in E. tenella development. IMPORTANCE Rhoptries are specialized secretory organelles found in zoite stages of apicomplexan parasites. In addition to well-conserved rhoptry neck proteins, their protein consists mostly of kinase proteins, highly divergent from eukaryotic kinases. Some of those kinases are described as major virulence factors in Toxoplasma gondii, secreted into the host cell to hijack signaling pathways. Most of those kinases remain to be characterized in Eimeria tenella. Deciphering their cellular function is a prerequisite to supporting their relevance as a druggable target in development of new means of Eimeria tenella control. Secreted divergent kinases that interact with host cell partners to modulate pathways are good candidates, as they coevolve with their host targets to ensure their function within the host and are less prone to mutations that would lead to drug resistance. The absence of any orthologous kinase in host cells makes these parasite kinases a promising drug target candidate.