Postnatal zinc deficiency due to giardiasis disrupts hippocampal and cerebellar development.

BACKGROUND: Giardiasis and zinc deficiency have been identified as serious health problems worldwide. Although Zn depletion is known to occur in giardiasis, no work has investigated whether changes occur in brain structures. METHODS: Three groups of gerbils were used: control (1), orogastrically inoculated on day 3 after birth with trophozoites of two isolates of Giardia intestinalis (HGINV/WB) group (2 and 3). Estimates were made at five ages covering: establishment of infection, Giardia population growth, natural parasite clearance and a post-infection age. QuantiChrome zinc assay kit, cresyl violet staining and TUNEL technique were used. RESULTS: A significant decrease (p<0.01) in tissue zinc was observed and persisted after infection. Cytoarchitectural changes were observed in 75% of gerbils in the HGINV or WB groups. Ectopic pyramidal neurons were found in the cornus ammonis (CA1-CA3). At 60 and 90 days of age loss of lamination was clearly visible in CA1. In the dentate gyrus (DG), thinning of the dorsal lamina and abnormal thickening of the ventral lamina were observed from 30 days of age. In the cerebellum, we found an increase (p<0.01) in the thickness of the external granular layer (EGL) at 14 days of age that persisted until day 21 (C 3 ± 0.3 µm; HGINV 37 ± 5 µm; WB 28 ± 3 µm); Purkinje cell population estimation showed a significant decrease; a large number of apoptotic somas were observed scattered in the molecular layer; in 60 and 90 days old gerbils we found granular cell heterotopia and Purkinje cell ectopia. The pattern of apoptosis was different in the cerebellum and hippocampus of parasitized gerbils. CONCLUSION: The morphological changes found suggest that neuronal migration is affected by zinc depletion caused by giardiasis in early postnatal life; for the first time, the link between giardiasis-zinc depletion and damaged brain structures is shown. This damage may explain the psychomotor/cognitive delay associated with giardiasis. These findings are alarming. Alterations in zinc metabolism and signalling are known to be involved in many brain disorders, including autism.

Distinguishing recrudescence from reinfection in lymphatic filariasis.

BACKGROUND: The Global Program to Eliminate Lymphatic Filariasis (GPELF) is the largest public health program based on mass drug administration (MDA). Despite decades of MDA, ongoing transmission in some countries remains a challenge. To optimise interventions, it is critical to differentiate between recrudescence and new infections. Since adult filariae are inaccessible in humans, deriving a method that relies on the offspring microfilariae (mf) is necessary. METHODS: We developed a genome amplification and kinship analysis-based approach using Brugia malayi samples from gerbils, and applied it to analyse Wuchereria bancrofti mf from humans in Côte d'Ivoire. We examined the pre-treatment genetic diversity in 269 mf collected from 18 participants, and further analysed 1-year post-treatment samples of 74 mf from 4 participants. Hemizygosity of the male X-chromosome allowed for direct inference of haplotypes, facilitating robust maternal parentage inference. To enrich parasite DNA from samples contaminated with host DNA, a whole-exome capture panel was created for W. bancrofti. FINDINGS: By reconstructing and temporally tracking sibling relationships across pre- and post-treatment samples, we differentiated between new and established maternal families, suggesting reinfection in one participant and recrudescence in three participants. The estimated number of reproductively active adult females ranged between 3 and 11 in the studied participants. Population structure analysis revealed genetically distinct parasites in Côte d'Ivoire compared to samples from other countries. Exome capture identified protein-coding variants with ∼95% genotype concordance rate. INTERPRETATION: We have generated resources to facilitate the development of molecular genetic tools that can estimate adult worm burdens and monitor parasite populations, thus providing essential information for the successful implementation of GPELF. FUNDING: This work was financially supported by the Bill and Melinda Gates Foundation (https://www.gatesfoundation.org) under grant OPP1201530 (Co-PIs PUF & Gary J. Weil). B. malayi parasite material was generated with support of the Foundation for Barnes Jewish Hospital (PUF). In addition, the development of computational methods was supported by the National Institutes of Health under grants AI144161 (MM) and AI146353 (MM). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

An Overview of Management Considerations for Mongolian Gerbils (Meriones unguiculatus), Cats (Felis catus), and Dogs (Canis familiaris) as Hosts for Brugia Infection.

Lymphatic filariasis is a mosquito-borne parasitic infection affecting an estimated 51.4 million people. Brugia malayi and Brugia pahangi are used in research because common nonprimate research species such as Mongolian gerbils (Meriones unguiculatus), cats (Felis catus), and dogs (Canis familiaris) can maintain the life cycle of these species of filarial nematodes. Although overall care and management of animals infected with Brugia spp. is relatively straightforward, there are some unique challenges and special considerations that must be addressed when managing a research colony infected with these parasites. In this review, we discuss our experience, share insight into biosafety and clinical management, and describe the expected clinical signs associated with Brugia infection in gerbils, cats, and dogs.

Toxocara canis infection in multiple types of animals: ophthalmological and pathological observations.

Human ocular toxocariasis (OT), caused by pet roundworm Toxocara canis (Nematoda Ascaridoidea), is a worldwide ocular parasitic infection that poses a severe threat to eyesight, especially in school-aged children. However, the infection process and pathological mechanism of Toxocara are difficult to study in the human body. This study was designed to explore long-term ocular manifestations in different rodents infected with Toxocara canis, uncovering the specific pathological mechanism and migration pathway of larvae after infection. The three types of experimental animals we selected were C57BL/6 mice, Mongolian gerbils and Brown Norway rats. Mice were randomly divided into five groups and infected orally with 1000, 2000, 4000, 8000 and 10,000 T. canis eggs; gerbils were randomly divided into four groups and infected orally with 1000, 2000, 4000 and 10,000 T. canis eggs; rats were randomly divided into three groups and infected orally with 2000, 6000 and 10,000 T. canis eggs. Their ocular changes were closely observed and recorded for at least 2 months. We also enucleated the eyeballs of some animals to perform pathological sectioning and hematoxylin-eosin staining. After 3 dpi (days post-infection), hemorrhagic lesions, mechanical injury of the retina and larval migration could be observed in some infected animals. The ocular infection and mortality rates tended to be stable at 7 dpi. Larval tissue, structure disorder and inflammation could be observed in the pathological sections. In conclusion, the mice infected with 2000 T. canis eggs and gerbils infected with 1000, 2000 and 4000 T. canis eggs showing obvious ocular lesions and lower mortality rates could provide a basis for long-term observation.

Geographical and Molecular Analysis of Haplotype Variations in Leishmania major Among Infected Iranian Phlebotomus papatasi.

PURPOSE: Leishmania major is main causative agent and Phlebotomus papatasi is only proven vector of Zoonotic Cutaneous Leishmaniasis (ZCL) in Iran. Human leishmaniasis is mostly susceptible to climatic conditions and molecular variations of Leishmania parasites within sandflies. METHODS: L. major was analyzed based on geographical, environmental, climatic changes and haplotype variations within P. papatasi. Molecular tools and different geographical aspects were employed using Arc-GIS software for mapping the geographic distribution of samples and other statistics tests. Fragments of ITS-rDNA, k-DNA, and microsatellite genes of Leishmania were used for PCR, RFLP, sequencing, and phylogenetic analyses. RESULTS: Totally 81 out of 1083 female P. papatasi were detected with Leishmania parasites: 70 and five were L. major and L. turanica, respectively. Golestan and Fars provinces had the highest (13.64%) and lowest (4.55%) infection rates, respectively. The infection rate among female P. papatasi collected from gerbil burrows was significantly higher (15.15%) than animal shelters, yards, and inside houses (4.48%) (P < 0.0%). Microsatellite was more sensitive (22.72%) than k-DNA (18.8%) and ITS-rDNA (7.48%). More molecular variations of L. major were found in Isfahan province. CONCLUSIONS: Arc-GIS software and other statistics tests were employed to find Leishmania positive and haplotype variations among sand flies. Geographical situations, altitude, climate, precipitation, humidity, temperature, urbanization, migrations, regional divergences, deforestation, global warming, genome instability, ecology, and biology of the sand flies intrinsically, and the reservoir hosts and neighboring infected locations could be reasons for increasing or decreasing the rate of Leishmania infection and haplotype variations.

Immunopathological investigation of a gerbil model of cutaneous leishmaniasis.

Leishmaniasis, caused by Leishmania species (intracellular protozoans), is a chronic, systemic disease that causes skin (cutaneous) and internal organ infections (visceral). Its prevalence has increased in recent years. Leishmania species are considered important pathogens that affect public health. After infecting an individual, the pathogen disrupts the immune system, but, there are not enough studies on which immune mechanisms are affected. The aim of this study was to establish a Leishmania major infection model (the causative agent of cutaneous leishmaniasis) in gerbils (Meriones unguiculatus) and to investigate the immune response in this model by examining the expression of important inflammatory genes (IL-1ß, IL-2, IL-6, IFN-É£ and TNF-α). The presence of parasites was confirmed by microscopic examination of samples taken from the lesions and culture studies. The expression of inflammatory cytokine genes was significantly increased in infected gerbils. The changes indicated that both the Th1 and Th2 pathways are activated in cutaneous leishmaniasis infection. Hence, different immunopathological mechanisms should be evaluated in the pathogenesis of the disease.

Ectoparasites associated with the Bushveld gerbil (Gerbilliscus leucogaster) and the role of the host and habitat in shaping ectoparasite diversity and infestations.

Rodents are known hosts for various ectoparasite taxa such as fleas, lice, ticks and mites. South Africa is recognized for its animal diversity, yet little is published about the parasite diversity associated with wild rodent species. By focusing on a wildlife-human/domestic animal interface, the study aims to record ectoparasite diversity and levels of infestations of the Bushveld gerbil, Gerbilliscus leucogaster, and to establish the relationship between ectoparasite infestation parameters and host- and habitat factors. Rodents (n = 127) were trapped in 2 habitat types (natural and agricultural) during 2014­2020. More than 6500 individuals of 32 epifaunistic species represented by 21 genera and belonging to 5 taxonomic groups (fleas, sucking lice, ticks, mesostigmatan mites and trombiculid mites) were collected. Mesostigmatan mites and lice were the most abundant and fleas and mesostigmatan mites the most prevalent groups. Flea and mesostigmatan mite numbers and mesostigmatan mite species richness was significantly higher on reproductively active male than female rodents. Only ticks were significantly associated with habitat type, with significantly higher tick numbers and more tick species on rodents in the natural compared to the agricultural habitat. We conclude that the level of infestation by ectoparasites closely associated with the host (fleas and mites) was affected by host-associated factors, while infestation by ectoparasite that spend most of their life in the external environment (ticks) was affected by habitat type.

Genomic analysis of Leishmania turanica strains from different regions of Central Asia.

The evolution in Leishmania is governed by the opposite forces of clonality and sexual reproduction, with vicariance being an important factor. As such, Leishmania spp. populations may be monospecific or mixed. Leishmania turanica in Central Asia is a good model to compare these two types. In most areas, populations of L. turanica are mixed with L. gerbilli and L. major. Notably, co-infection with L. turanica in great gerbils helps L. major to withstand a break in the transmission cycle. Conversely, the populations of L. turanica in Mongolia are monospecific and geographically isolated. In this work, we compare genomes of several well-characterized strains of L. turanica originated from monospecific and mixed populations in Central Asia in order to shed light on genetic factors, which may drive evolution of these parasites in different settings. Our results illustrate that evolutionary differences between mixed and monospecific populations of L. turanica are not dramatic. On the level of large-scale genomic rearrangements, we confirmed that different genomic loci and different types of rearrangements may differentiate strains originated from mixed and monospecific populations, with genome translocations being the most prominent example. Our data suggests that L. turanica has a significantly higher level of chromosomal copy number variation between the strains compared to its sister species L. major with only one supernumerary chromosome. This suggests that L. turanica (in contrast to L. major) is in the active phase of evolutionary adaptation.

Fenbendazole treatment against Dentostomella translucida in Syrian golden hamsters.

Dentostomella translucida is an oxyurid nematode that was first discovered in the Mongolian gerbil but has also been detected in other wild and housed rodents. In conventional laboratory animals, oxyurid nematode parasites are widespread infections. A proven treatment strategy for pinworm eradication is the oral application of benzimidazoles, such as fenbendazole. In general, this drug is regarded as safe with minimal side effects. Nevertheless, in Sprague Dawley rats, a significantly reduced litter size could be seen after longer treatment with fenbendazole. Even though Dentostomella translucida was already described in Syrian golden hamsters (Mesocricetus auratus), data on treatment with fenbendazole and its effects on reproduction is lacking. Therefore, the main purposes of the study were (1) the verification of the effectiveness of fenbendazole as medicated feed (150 ppm) against this parasite in naturally infected Syrian golden hamsters in conventional husbandry and (2) monitoring of possible effects on reproduction during the treatment. Results show that fenbendazole treatment was highly effective against Dentostomella translucida, as numbers of pinworm eggs in the faeces were significantly reduced already after the first week of treatment in all animals. After four weeks of treatment, eggs were eradicated entirely. Interestingly, the average weaning weight was significantly reduced during treatment, but the litters were in good health.

Identification and phylogenic analysis of Leishmania species among patients and reservoir hosts based on N-acetylglucosamine-1-phosphate transferase gene in Central Iran.

Leishmaniosis, a vector-born disease that infects humans and other vertebrates, is the result of infection with Leishmania species belong to the family Trypanosomatidae. The present study was performed to determine the status of cutaneous leishmaniosis in Isfahan province. Samples were taken from the margin of skin ulcers of patients with suspected CL referred to the medical health centers in Isfahan province. Also, ear and snout samples were taken from the rodents. In total, 85 parasitologically positive samples were subjected to the PCR-RFLP method based on the nagt gene for identification of Leishmania species, also 11 samples were subjected to sequencing and phylogenetic analysis. For all positive samples, a 1450-1460 bp band of the nagt gene was amplified in PCR method. The digestion pattern of ACC1 enzyme in 79 of patients indicated L. major and in one sample was similar to L. tropica. Four rodent reservoirs distingue as L. major and one sample as L. turanica. Phylogenetic analysis confirmed the species identification and three haplotypes were reported. The results of the current study showed that L. major is the predominant species of Leishmania parasites in Isfahan province and the main reservoir of CL is Rhombomys opimus. Also, the nagt gene is a useful and practical marker for determining different species of Leishmania parasites as well as their phylogenetic analysis.

Cutaneous leishmaniasis in Iran: A review of epidemiological aspects, with emphasis on molecular findings.

Leishmania parasites can cause zoonotic cutaneous leishmaniasis (CL) by circulating between humans, rodents, and sandflies in Iran. In this study, published data were collected from scientific sources such as Web of Science, Scopus, PubMed, Springer, ResearchGate, Wiley Online, Ovid, Ebsco, Cochrane Library, Google scholar, and SID. Keywords searched in the articles, theses, and abstracts from 1983 to 2021 were cutaneous leishmaniasis, epidemiology, reservoir, vector, climatic factors, identification, and Iran. This review revealed that CL was prevalent in the west of Iran, while the center and south of Iran were also involved in recent years. The lack of facilities in suburban regions was an aggravating factor in the human community. Some parts of southern Iran were prominent foci of CL due the presence of potential rodent hosts in these regions. Rhombomys opimus, Meriones lybicus, and Tatera indica were well-documented species for hosting the Leishmania species in Iran. Moreover, R. opimus has been found with a coinfection of Leishmania major and L. turanica from the northeast and center of Iran. Mashhad, Kerman, Yazd, and sometimes Shiraz and Tehran foci were distinct areas for L. tropica. Molecular identifications using genomic diagnosis of kDNA and ITS1 fragments of the parasite indicated that there is heterogeneity in leishmaniasis in different parts of the country. Although cutaneous leishmaniasis has been a predicament for the health system, it is relatively under control in Iran.

Title: Leishmaniose cutanée en Iran : une synthèse des aspects épidémiologiques, mettant l'accent sur les découvertes moléculaires. Abstract: Les parasites Leishmania peuvent établir une leishmaniose cutanée zoonotique (LC) en circulant entre les humains, les rongeurs et les phlébotomes en Iran. Dans cette étude, les données publiées ont été collectées à partir de ressources scientifiques telles que Web of Science, Scopus, PubMed, Springer, ResearchGate, Wiley Online, Ovid, Ebsco, Cochrane Library, Google Scholar et SID. Les mots-clés recherchés dans les articles, les thèses et les résumés de 1983 à 2021 étaient leishmaniose cutanée, épidémiologie, réservoir, vecteur, facteurs climatiques, identification et Iran. Cet examen a révélé que la LC est répandue dans l'ouest de l'Iran, tandis que le centre et le sud de l'Iran sont également impliqués ces dernières années. Le manque d'équipements dans les régions suburbaines est un facteur aggravant dans la communauté humaine. Certaines parties du sud de l'Iran sont des foyers importants de LC en raison de la présence d'hôtes potentiels de rongeurs dans ces régions. Rhombomys opimus, Meriones lybicus et Tatera indica sont des espèces bien documentées pour héberger les espèces de Leishmania en Iran. De plus, R. opimus a été trouvé avec une co-infection de Leishmania major et L. turanica au nord-est et au centre de l'Iran. Mashhad, Kerman, Yazd et parfois des foyers de Shiraz et de Téhéran sont des zones distinctes pour L. tropica. Les identifications moléculaires utilisant le diagnostic génomique des fragments d'ADNk et ITS1 du parasite ont indiqué qu'il existe une hétérogénéité dans la leishmaniose dans différentes parties du pays. Bien que la leishmaniose cutanée ait été une situation difficile pour le système de santé, elle est relativement contrôlée en Iran.

High-resolution melting analysis identifies reservoir hosts of zoonotic Leishmania parasites in Tunisia.

BACKGROUND: Leishmaniasis is endemic in Tunisia and presents with different clinical forms, caused by the species Leishmania infantum, Leishmania major, and Leishmania tropica. The life cycle of Leishmania is complex and involves several phlebotomine sand fly vectors and mammalian reservoir hosts. The aim of this work is the development and evaluation of a high-resolution melting PCR (PCR-HRM) tool to detect and identify Leishmania parasites in wild and domestic hosts, constituting confirmed (dogs and Meriones rodents) or potential (hedgehogs) reservoirs in Tunisia. METHODS: Using in vitro-cultured Leishmania isolates, PCR-HRM reactions were developed targeting the 7SL RNA and HSP70 genes. Animals were captured or sampled in El Kef Governorate, North West Tunisia. DNA was extracted from the liver, spleen, kidney, and heart from hedgehogs (Atelerix algirus) (n = 3) and rodents (Meriones shawi) (n = 7) and from whole blood of dogs (n = 12) that did not present any symptoms of canine leishmaniasis. In total, 52 DNA samples were processed by PCR-HRM using both pairs of primers. RESULTS: The results showed melting curves enabling discrimination of the three Leishmania species present in Tunisia, and were further confirmed by Sanger sequencing. Application of PCR-HRM assays on reservoir host samples showed that overall among the examined samples, 45 were positive, while seven were negative, with no Leishmania infection. Meriones shawi were found infected with L. major, while dogs were infected with L. infantum. However, co-infections with L. major/L. infantum species were detected in four Meriones specimens and in all tested hedgehogs. In addition, multiple infections with the three Leishmania species were found in one hedgehog specimen. Sequence analyses of PCR-HRM products corroborated the Leishmania species found in analyzed samples. CONCLUSIONS: The results of PCR-HRM assays applied to field specimens further support the possibility of hedgehogs as reservoir hosts of Leishmania. In addition, we showed their usefulness in the diagnosis of canine leishmaniasis, specifically in asymptomatic dogs, which will ensure a better evaluation of infection extent, thus improving elaboration of control programs. This PCR-HRM method is a robust and reliable tool for molecular detection and identification of Leishmania and can be easily implemented in epidemiological surveys in endemic regions.

Adaptation to a novel host and performance trade-off in host-generalist and host-specific insect ectoparasites.

We investigated the performance trade-offs of fleas (Siphonaptera) while adapting to a novel host using two host generalists (Xenopsylla conformis and Xenopsylla ramesis) and one host specialist (Parapulex chephrenis) maintained on their principal hosts (Meriones crassus for Xenopsylla and Acomys cahirinus for P. chephrenis). We asked whether, over generations, (i) a host generalist may become a specialist by evolving the ability to exploit a novel host and losing the ability to exploit an original host and (ii) a host specialist can become a generalist by evolving the ability to exploit a novel host without losing the ability to exploit an original host. We established an experimental line of each species on a novel host (Acomys russatus for Xenopsylla and M. crassus for P. chephrenis) and maintained this line on this host during 23 generations. We compared reproductive performance of progenitors of each line and their descendants when they exploited either original or novel host in terms of egg number and size, hatching success, offspring production, and offspring size. We found changes in performance over generations in female offspring size only. Xenopsylla conformis demonstrated a tendency to become a host specialist (increased performance on the novel host with a concomitant decreased performance on the original host), whereas P. chephrenis demonstrated a tendency to become a host generalist (increased performance on the novel host without a concomitant decreased performance on the original host). We conclude that the probability of generalist to specialist transition, and vice versa, is context-dependent and varies between species.

Zoonotic vector-borne bacteria in wild rodents and associated ectoparasites from Tunisia.

Wild rodents are considered as potential carriers of several zoonotic vector-borne bacteria but their epidemiology is poorly understood in Tunisia. A total of 305 biological samples (100 spleens, 100 livers, 100 kidneys, and 5 pooled ectoparasites (Xenopsylla cheopis, Laelaps echidninus, Ornithonyssus sp., Hoplopleura sp. and eggs of the rat fleas)) were collected from 100 wild rodents from three Tunisian governorates. Molecular screening was performed to reveal infections with main vector-borne bacteria. Captured rodents belonged to three rodent genera and species including Rattus rattus (n = 51, 51%), Meriones shawi (n = 24, 24%) and Mus musculus (n = 25, 25%). Examined rodents were found to be heavily infested by the rat flea X. cheopis (n = 32, 47%) and the rat mite L. echidninus (n = 22, 32.3%). However, the rat mite Ornithonyssus sp. (n = 13, 19.1%) and the rat lice Hoplopleura sp. (n = 1, 1.5%) were rarely identified. Based on 16S rRNA and msp4 genes, infection with Anaplasmataceae bacteria was detected in six specimens of R. rattus and one M. shawi. Pathogenic A. phagocytophilum (n = 1), A. phagocytophilum-like 1 (Anaplasma sp. Japan) (n = 1), and A. ovis (n = 5) were identified. On the basis of ompB, ompA and gltA genes, infection with Rickettsia spp. was identified in three specimens of R. rattus and one of M. shawi. Five Rickettsia species of the spotted fever group, corresponding to R. monacensis, R. helvetica, R. massiliae, R. africae, and R. aeschlimannii, were detected in mixed infections. Bartonella henselae DNA was also found in two R. rattus, based on rpoB partial sequences. All revealed Anaplasma, Rickettsia and Bartonella bacteria were detected in spleen samples. Ehrlichia, Coxiella and Borrelia spp. were not identified in any of the tested samples. In Tunisia, this is the first report indicating infections with Anaplasma, Rickettsia and Bartonella spp. in wild rodents, particularly present alongside domestic livestock and human. This represents a serious risk of potential bacterial transmission. Thus, controlling rodent population in animal herds, residential areas and sensitizing local people to this risk seem absolutely necessary.

Evaluation of Orally Administered Anthelmintic Treatment Options for Dentostomella translucida in Naturally Infected Mongolian Gerbils (Meriones unguiculatus)

Objective: This study aimed to evaluate the efficacy of eprinomectin, moxidectin and fenbendazole for treating Dentostomella translucida infections in naturally infected Mongolian gerbils (Meriones unguiculatus). Methods: A total of 28 gerbils were placed in individually numbered cages to determine the individual animal parasite load. Eggs per gram (EPG) counts were used to estimate the efficacy of the drugs. The day before the anthelmintic administration was denoted as day 0, and the EPG counts were determined by the McMaster technique from the stool removed from the cage bottom on days 7, 14, 21 and 28. The animals were assigned to one of four treatment groups according to their day 0 EPG counts. The orally administered drugs in the treatment groups were eprinomectin (15 mg/kg), moxidectin (0.4 mg/kg) and fenbendazole (12 mg/kg) for groups 1-3, respectively. The fourth group served as the control (without any drug administration). Results: Treatment efficacy was evaluated based on weekly EPG counts. The values decreased to zero in the fenbendazole group at 4 weeks of follow-up after treatment, and no parasite was found in any of the repeated examinations. The eprinomectin and moxidectin groups exhibited a fluctuating EPG state on both individual and group basis. Conclusion: D. translucida, which is known as the specific parasite of gerbils, can easily affect other members of the animal colony; thus, the control of its presence in gerbil breeding units is necessary. Therefore, the reported effective drug treatments are important for the fight against the investigated parasitic infection.

A rapid, parasite-dependent cellular response to Dirofilaria immitis in the Mongolian jird (Meriones unguiculatus).

BACKGROUND: The Mongolian jird (Meriones unguiculatus) has long been recognized as a permissive host for the filarial parasite Brugia malayi; however, it is nonpermissive to another filarial parasite, canine heartworm (Dirofilaria immitis). By elucidating differences in the early response to infection, we sought to identify mechanisms involved in the species-specific clearance of these parasites. We hypothesized that the early clearance of D. immitis in intraperitoneal infection of the jird is immune mediated and parasite species dependent. METHODS: Jird peritoneal exudate cells (PECs) were isolated and their attachment to parasite larvae assessed in vitro under various conditions: D. immitis and B. malayi cultured separately, co-culture of both parasites, incubation before addition of cells, culture of heat-killed parasites, and culture with PECs isolated from jirds with mature B. malayi infection. The cells attaching to larvae were identified by immunohistochemistry. RESULTS: In vitro cell attachment to live D. immitis was high (mean = 99.6%) while much lower for B. malayi (mean = 5.56%). This species-specific attachment was also observed when both filarial species were co-cultured, with no significant change from controls (U(9, 14) = 58.5, p = 0.999). When we replicated these experiments with PECs derived from jirds subcutaneously infected with B. malayi, the results were similar (99.4% and 4.72% of D. immitis and B. malayi, respectively, exhibited cell attachment). Heat-killing the parasites significantly reduced cell attachment to D. immitis (mean = 71.9%; U(11, 14) = 7.5, p < 0.001) while increasing attachment to B. malayi (mean = 16.7%; U(9, 15) = 20, p = 0.002). Cell attachment to both species was reduced when larvae were allowed a 24-h pre-incubation period prior to the addition of cells. The attaching cells were identified as macrophages by immunohistochemistry. CONCLUSIONS: These results suggest a strongly species-dependent response from which B. malayi could not confer protection by proxy in co-culture. The changes in cell attachment following heat-killing and pre-incubation suggest a role for excretory/secretory products in host immune evasion and/or antigenicity. The nature of this attachment is the subject of ongoing study and may provide insight into filarial host specificity.

Development of Acanthocheilonema viteae in Meriones shawi: Absence of microfilariae and production of active ES-62.

AIMS: ES-62 is a well-studied anti-inflammatory molecule secreted by L4-adult stage Acanthocheilonema viteae. We maintain the life cycle of A viteae using Meriones libycus as the definitive host. Here, we investigated whether the full life cycle could be maintained, and functional ES-62 produced, in a related jird species-Meriones shawi. METHODS AND RESULTS: Adult worms were produced in comparable numbers in the two species, but very few microfilariae (MF) were observed in the M shawi bloodstream. M shawi ES-62 produced ex vivo was functional and protective in a mouse model of arthritis. Myeloid-derived cells from naïve and infected jirds of both species were compared with respect to ROS production and osteoclast generation, and some differences between the two species in both the absence and presence of infection were observed. CONCLUSIONS: The life cycle of A viteae cannot be successfully completed in M shawi jirds but L3 stage worms develop to adulthood and produce functional ES-62. Preliminary investigation into jird immune responses suggests that infection can differentially modulate myeloid responses in the two species. However, species-specific reagents are required to understand the complex interplay between A viteae and its host and to explain the lack of circulating MF in infected M shawi jirds.

The Potential of Systemic Control of Sand Flies Using Fipronil in the Novel Leishmania major (Kinetoplastida: Trypanosomatidae) Reservoirs Meriones tristrami (Rodentia: Muridea) and Meriones crassus (Rodentia: Muridea).

Leishmania major (Yakimoff & Schokhor, 1914), an important causative agent of Old World Cutaneous Leishmaniasis (CL), is transmitted by sand flies among a limited number of gerbilline reservoir-species. We can take advantage of this strong dependency to break the pathogen transmission cycle by using systemic insecticides that render the host toxic to the blood-feeding vector. We evaluated the potential of this approach with two novel reservoir species, incriminated for CL expansion in several sites in the Middle East. Specifically, we evaluated: 1) the residuality of the systemic insecticide fipronil in Meriones tristrami (Thomas, 1892) fed on fipronil-treated baits and 2) the treatments' adulticide effect on sand flies that blood fed on treated and untreated M. tristrami and M. crassus (Sundevall, 1842). We fed M. tristrami with food pellets containing 0.1 g/kg fipronil and used gas chromatograph-mass spectrometery analysis and bioassays to examine its residual toxicity to blood-feeding female sand flies. In M. tristrami, fipronil was rapidly metabolized to fipronil sulfone, found in the blood, urine, and feces for ≥31 d after fipronil admission. The survival of sand flies that blood fed on fipronil-treated M. tristrami and M. crassus was significantly reduced for at least 15 and 9 d respectively, after fipronil admission. These results hold promise for the potential contribution of systemic control approaches to CL integrated management strategies against novel CL (due to L. major) outbreaks in Israel and elsewhere.

Systemic Control of Cutaneous Leishmaniasis Sand-Fly Vectors: Fipronil-Treated Rodent Bait Is Effective in Reducing Phlebotomus papatasi (Diptera: Psychodidae) Female Emergence Rate From Rodent Burrows.

The strong dependency of some vectors on their host as a source of habitat can be viewed as a weak link in pathogen's transmission cycles using the vertebrate host as a 'Trojan horse' to deliver insecticides directly to the vector-host point of contact (hereafter 'systemic control'). This could, simultaneously, affect the survival of blood-feeding females and coprophagic larvae. Sand-flies, vectors of leishmaniasis worldwide, are often dependent on their bloodmeal host as a source of habitat and may therefore be good candidates for systemic control. In the present study, we field-tested this methodology by baiting Meriones crassus (Sundevall, 1842) (Rodentia:Muridea) with Fipronil-treated food pellets and evaluated its effect on reducing sand-fly emergence rate, in general, and of that of blood-fed females, in particular. We demonstrated 86% reduction in the abundance of female sand-flies that exit burrows of Fipronil-treated jirds, whereas male abundance was unaffected. Furthermore, whereas in control burrows 20% of the females were blood-fed, in treatment burrows no blood-fed females were detected. Sand-fly abundance outside the burrows was not affected by burrow treatment. This highlights the focal specificity of this method: affecting female sand-flies that feed on the reservoir host. This should result in the reduction of the pathogen transmission rate in the vicinity of the treated area by reducing the prevalence of leishmania-infected sand-fly females. These results hold promise for the potential of the systemic control approach in this system. Our next-step goal is to test this methodology at a large-scale cutaneous leishmaniasis control program.

Age range implications of rats over Strongyloides venezuelensis infection.

OBJECTIVE: To evaluate the dynamics of S. venezuelensis infection in Wistar rats of different age ranges. DESIGN: Thirty-five (n = 35, 7 per group) male Wistar rats were distributed according to age into five groups: 2, 3, 6, 12 and 18 months old (mo). The rats were infected by S. venezuelensis and eggs per gram of feces (EPG) were measured at 3, 9, 15 and 21 days post-infection (dpi). All animals were killed at 21 dpi, thymus, lungs and small intestines were removed, and relative weight calculated. The adult worms recovered from the small intestines and blood cells were counted. RESULTS: Rats in advanced age presented higher parasite oviposition at 9 dpi and posterior reduction of EPG, while young rats still showed higher oviposition at 15 dpi and 21 dpi. At 12 and 18 mo, the rats had greater number of adult worms, which with low fecundity, eosinophilia and least concentration of monocytes. The fecundity of worms was more expressive in young rats. A strong correlation was observed between age and EPG at 9 dpi (R = 0.72, p < 0.0001), at 15 (R = -0.66, p < 0.0001) and at 21 dpi (R = -0.65, p < 0.0001), as well as age and numbers of worms at 21 dpi (R = 0.74, p < 0.0001). The relative weight of the thymus, lungs and small intestines were higher in rats at 2 and 3 mo in comparison to the older groups of rats. CONCLUSIONS: Aging process interfered on host-parasite relationship and changed the dynamics of infection of S. venezuelensis in Wistar rats.