Can an entomopathogenic nematode serve, as proxy for strongyles, in assessing the anthelmintic effects of phenolic compounds?

As gastro-intestinal nematodes (GINs) become increasingly resistant to chemical anthelmintics, and because consumers scrutinize chemical residues in animal products, the use of herbal anthelmintics and in particular, phenolic compounds, has become attractive. Most life stages of GINs cannot be grown in the lab as they are obligatory parasites, which limits our understanding of the effects of phenolic compounds on their parasitic stages of life. We hypothesized that a species phylogenetically close to GINs and grown in vitro, the insect-parasitic nematode Heterorhabditis bacteriophora (Rhabditida; Heterorhabditiade), when fed with Photorhabdus luminescens exposed to plant phenolics, can serve, as proxy for strongyles, in assessing the anthelmintic effects of phenolic compounds. We compared the development of H. bacteriophora infective juveniles (IJ) and the exsheathment rate of L3 larvae of the strongyle Teladorsagia circumcincta and Trichostrongylus colubriformis when exposed to catechin, rutin, chlorogenic and gallic acids, and myricetin. Gallic acid had the highest impact in terms of IJ mortality but the highest impairment of IJ development to adulthood was imposed by myricetin. The studied compounds were not lethal to GINs stricto sensu but we consider that the practical implications of total exsheathment inhibition and mortality on GIN populations are similar. Catechin and rutin had similar effects on rhabditid and strongyles: they imposed ca. 90% lethality of IJs at concentrations higher than 1200 ppm and the remaining live IJs did not develop further, and they also totally inhibited strongyle L3 exsheathment in a dose-response fashion. Gallic acid was 100% lethal to IJs exposed above 300 ppm and chlorogenic acid caused 87% mortality above 1200 ppm, with no development for the surviving IJs but for all lower concentrations, all the IJs developed to adult stages. Likewise, gallic and chlorogenic acids did not affect the exsheatment of GIN L3 larvae. Therefore, a discrepancy between the effects of gallic and chlorogenic acids on the development of rhabditid IJs and exsheathment of GIN L3 larvae was found only when they were exposed to high concentrations. A dose-response of IJ lethality to myricetin was found, with no IJ development between 150 and 2400 ppm; but contrary to the other compounds, myricetin also impaired IJ development of IJs above 10 ppm in a dose-response manner and showed dose-responses in the L3 exsheathment. Apart for the high rates of lethality imposed on IJs by gallic and chlorogenic acids at high concentration, these results suggest that H. bacteriophora fed P. luminescens exposed to phenolics shows potential to serve as model in studies of the anthelmintic effects of phenolics in GIN.

Phylogenetic analysis of Spirocerca lupi and Spirocerca vulpis reveal high genetic diversity and intra-individual variation

Background

Spirocerca lupi is a parasitic nematode of canids that can lead to a severe and potentially fatal disease. Recently, a new species, Spirocerca vulpis, was described from red foxes in Europe, suggesting a high genetic diversity of the Spirocerca spp. infecting canids. The genetic variation and phylogenetic relationships of S. lupi collected from naturally-infected domestic dogs from Australia, Hungary, Israel, Italy, India and South Africa, and S. vulpis from red foxes from Bosnia and Herzegovina, Italy and Spain, was studied using mitochondrial and rDNA markers.

Results

A high intra-individual variation was found in the first internal transcribed spacer (ITS1) locus in all Spirocerca spp., ranging between 0.37–2.84%, with up to six haplotypes per specimen. In addition, a combination of phylogenetic and haplotype analyses revealed a large variability between S. lupi specimens collected from different geographical locations using the ITS1 (0.37–9.33%) and the cytochrome c oxidase subunit 1 (cox1) gene (1.42–6.74%). This genetic diversity led to the identification of two S. lupi genotypes circulating among dogs (PTP support > 0.829), including genotype 1 found in S. lupi from Australia, India, Israel and South Africa, and genotype 2 represented by specimens from Hungary and Italy. These genotypes presented pairwise nucleotide distances of 0.14%, 8.06% and 6.48 ± 0.28% in the small rDNA subunit (18S), ITS1 and cox1 loci, respectively. Additionally, Nei’s genetic distance in the ITS1 showed a further subdivision of genotype 1 worms into 1A (Israel and South Africa) and 1B (Australia and India). A morphological analysis of the anterior and posterior extremities of genotype 1 and genotype 2 worms using scanning electron microscopy did not show any differences between the specimens, contrary to the morphological differences between S. lupi and S. vulpis.

Conclusions

These findings demonstrate the high genetic variability among Spirocerca spp. from different geographical locations, thereby expanding our understanding of the epidemiology, evolution and phylogenetic variability within the genus.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3202-0) contains supplementary material, which is available to authorized users.

Effects of selected Palestinian plants on the in vitro exsheathment of the third stage larvae of gastrointestinal nematodes

Background

Gastrointestinal parasites are one of the main restrictions to small ruminant production. Their pathological importance is primarily related to the major production losses, in quantity or quality, induced by the direct action of worms. Control of these parasites is based exclusively on the frequent use of anthelmintic drugs. However, the resistance to anthelmintics in worm populations after commercialisation of chemical drugs is now widespread. Therefore, there is a need to find new natural resources to ensure sustainable and effective treatment and control of these parasites. The aim of this study was to evaluate the anthelmintic activity, as minimum inhibitory concentration (IC₅₀ mg/mL), of different plant extracts using larval exsheathment inhibition assay using a two-species but steady population of parasitic nematodes (ca. 20% Teladorsagia circumcinta and 80% Trichostrongylus colubriformis).

Results

The study showed that the ethanolic extracts of 22 out of the 48 plant extracts, obtained from 46 plant species, have an inhibitory effect >50% (at concentrations of 100 mg/mL) on the third stage larvae (L3) of the nematodes exhibited the strongest inhibition activity (94%) with IC₅₀ of 0.02 mg/mL, where other members of the Rhamnaceae family have shown to possess strong anthelmintic activity (70–89%).

Conclusions

Plant extracts are potential rich resources of anthelmintics to combat helminthic diseases. Our results suggest that extracts from Rhamnus elaternus, Epilobium hirsutum, Leucaena leucocephala and Rhamnus palaestinus have promising anthelmintic activity, with potential applications in animal therapeutics and feed.

Detection and quantification of Spirocerca lupi by HRM qPCR in fecal samples from dogs with spirocercosis

Background

Spirocerca lupi, the dog oesophageal nematode, causes a potentially fatal disease in domestic dogs, and is currently clinically diagnosed by coproscopy and oesophagoscopy. To date, a single molecular method, a semi-nested PCR, targeting the cox1 gene, has been developed to aid in the diagnosis of spirocercosis. The present study describes three novel high-resolution melt (HRM) quantitative PCR (qPCR) assays targeting fragments of the ITS1, 18S and cytb loci of S. lupi. The performance of these molecular assays in feces was compared to fecal flotation and to the previously described cox1 gene semi-nested PCR in 18 fecal samples from dogs with clinical oesophageal spirocercosis diagnosed by oesophagoscopy.

Results

The HRM qPCR for ITS1 and 18S were both able to detect 0.2 S. lupi eggs per gram (epg), while the HRM qPCR for the cytb and the semi-nested PCR for the cox1 detected 6 epg and 526 epg, respectively. Spirocerca lupi was detected in 61.1%, 44.4%, 27.8%, 11.1% and 5.6% of the fecal samples of dogs diagnosed with spirocercosis by using the ITS1 and 18S HRM qPCR assays, fecal flotation, cytb HRM qPCR and cox1 semi-nested PCR, respectively. All dogs positive by fecal flotation were also positive by ITS1 and 18S HRM qPCRs. Quantification of S. lupi eggs was successfully achieved in the HRM qPCRs and compared to the fecal flotation with no significant difference in the calculated concentrations between the HRM qPCRs that detected the 18S and ITS1 loci and the fecal flotation. The HRM qPCR for the 18S cross-amplified DNA from Toxocara canis and Toxascaris leonina. In contrast, the HRM qPCR for ITS1 did not cross-amplify DNA from other canine gastrointestinal parasites.

Conclusions

This study presents two new molecular assays with significantly increased sensitivity for confirming and quantifying fecal S. lupi eggs. Of these, the HRM qPCR for ITS1 showed the best performance in terms of the limit of detection and absence of cross-amplification with other parasites. These assays will be useful in detecting infection and for follow-up during therapy.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2374-3) contains supplementary material, which is available to authorized users.

Molecular characterization of Trichinella species from wild animals in Israel

Trichinellosis is a worldwide disease caused by nematode worms of the genus Trichinella, frequently diagnosed in Israel. However, the identity of the Israeli isolates have not been studied. Here we describe the molecular characterization of 58 isolates collected from jackals (Canis aureus), wild boar (Sus scrofa), foxes (Vulpes vulpes) and a wolf (Canis lupus) in central and northern Israel. Isolates were analyzed using the multiplex PCR analysis encompassing expansion segment V (ESV) and internal sequence 1 (ITS-1) markers, which identified 52 of the 58 samples. Out of the six unidentified samples, four were successfully identified using extended PCR assays for ESV and ITS-1, developed in this study. Our analysis identified 44 isolates as T. britovi, 8 as T. spiralis, four mixed infections, and two isolates were not identified. Clonal analysis of the ITS-1 sequences from six isolates confirmed the initial identification of four mixed infections. These results show that the prevalent species in Israel are T. britovi and T. spiralis, with nearly 7% (4 of 58) incidence of mixed infection.

Molecular characterization of the Israeli B. bigemina vaccine strain and field isolates

The present study demonstrated the genetic character of the Israeli Babesia bigemina vaccine strain and field isolates, based on rap-1a and rap-1c gene sequences. The RAP-1a of blood-derived Israeli B. bigemina field isolates shared 100% amino acid sequence identity. However, comparison of RAP-1c from various Israeli B. bigemina field isolates revealed that the total sequence identity among the field isolates ranged from 98.2 to 100%. High identity was observed when RAP-1a sequences from the Israeli vaccine strain and field isolates were compared with RAP-1a from Egypt, Syria, Mexico and South Africa, while, the Israeli RAP-1c sequences showed the highest identity to the Mexican isolate JG-29 and to the PR isolate from Puerto-Rico. Based on sequence variations between the rap-1a of the vaccine strain and that of the field isolate, and between the rap-1c of the vaccine strain and that of the field isolates, nPCR-RFLP procedures were developed that enable, for the first time differentiation between the Israeli B. bigemina vaccine strain and field-infection isolates. These assays could serve as fast and sensitive methods for detection and differentiation between Israeli B. bigemina vaccine strains and field isolates, as well as for epidemiological investigations.

Differentiation between Israeli B. bovis vaccine strain and field isolates

The present study demonstrated for the first time the ability to distinguish between the Israeli Babesia bovis vaccine strain and field isolates. The existence of an additional EcoRI restriction site in the rhoptry-associated protein-1 (rap-1) gene, which is unique to the Israeli vaccine strain, and the abolition of one of the HaeIII restriction sites in the rap-1 gene of the vaccine strain enabled distinction between the Israeli B. bovis vaccine strain and field isolates, and this was the basis for polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) development. ClustalW sequence alignment of RAP-1-deduced amino acids of the Israeli B. bovis strains and of field isolates showed that the total sequence identity among the RAP-1 amino acid sequences ranged from 97.5% to 100%. However, comparison between amino acids of RAP-1 of the Israeli vaccine strain and of field isolates, on the one hand, and B. bovis strains from Argentina, Mexico, Brazil, and USA, on the other hand, revealed 90% identity. The PCR-RFLP assay offered the great advantage of being able to distinguish between vaccine and field isolates in mixtures and provide new insight into the molecular epidemiology of B. bovis infections in Israel.

Short communication: effect of pomegranate-residue supplement on Cryptosporidium parvum oocyst shedding in neonatal calves

Cryptosporidium parvum is considered one of the most common enteropathogens, responsible for the high incidence of diarrhea and deleterious implications on immunity and health in neonatal calves. The pomegranate is well known for its health-promoting properties. Two experiments were designed to test the antiparasitical and antidiarrheal effects of concentrated pomegranate extract (CPE) supplement in milk in neonatal Holstein calves. Forty-one calves were randomly divided into control (n=20) and treatment (n=21) groups. For the first experiment, the treatment group was supplemented with 3.75% CPE in the daily milk ration, between 3 and 14 d of age, whereas the control group received only milk. Fecal samples were collected between d 5 and 13 to quantify Cryptosporidium oocysts, and the duration and intensity of diarrhea were evaluated. Reduced fecal oocyst count and diarrhea intensity and duration were revealed in the 3.75% CPE calves. No difference was noted in average daily gain between groups. In a second experiment, which was designed to test the effect of a lower CPE concentration (0.6% of daily milk allocation), no effects on fecal oocyst count and average daily gain were observed. However, compared with control, the lower CPE group was characterized by a shorter duration of diarrhea and higher weight gain among males at 14 d of age. These results suggest that the CPE supplement-to-calf milk ratio may potentially alleviate intestinal morbidity caused by Cryptosporidium.

Temporal association of ambient temperature and relative humidity with Spirocerca lupi infection of Onthophagus sellatus: a 14-year longitudinal study

The parasitic nematode Spirocerca lupi causes major morbidity and mortality in dogs. The scarab beetle Onthophagus sellatus is its major intermediate host in Israel. We investigated the prevalence of beetle infection by S. lupi in different years between 1994 and 2008. The average monthly maximum and minimum relative humidity (RH) and ambient temperature (AT) throughout the study period were calculated based on daily meteorological data. The infection prevalence decreased over the study period, possibly due to a chronological change resulting from increased preventive treatment of dogs against S. lupi, or climate change. Multivariate analysis was performed for these two hypotheses. Under the first hypothesis, chronological change was forced into the model, and environmental variables were inserted stepwise. The final model included beetle-collection date, minimum RH (RH min) during the month preceding beetle collection, its interaction with maximal AT (AT max) during that same month, and the interaction of maximal RH (RH max) and AT max, during the month of beetle collection. Under the second hypothesis, chronological change was not forced. The final model included RH max during the month of beetle collection, average RH (RHave) during the month preceding beetle collection, and its interaction with AT max during the latter month. The results suggest that under both hypotheses, RH and AT during the month preceding beetle collection influence S. lupi's ability to develop and survive in O. sellatus, and may be used to predict the risk to dogs of S. lupi infection.

A novel bacterial symbiont in the nematode Spirocerca lupi

Background

The parasitic nematode Spirocerca lupi (Spirurida: Thelaziidae), the canine esophageal worm, is the causative agent of spirocercosis, a disease causing morbidity and mortality in dogs. Spirocerca lupi has a complex life cycle, involving an obligatory coleopteran intermediate host (vector), an optional paratenic host, and a definitive canid host. The diagnosis of spirocercosis is challenging, especially in the early disease stages, when adult worms and clinical signs are absent. Thus, alternative approaches are needed to promote early diagnosis. The interaction between nematodes and their bacterial symbionts has recently become a focus of novel treatment regimens for other helminthic diseases.

Results

Using 16S rDNA-based molecular methods, here we found a novel bacterial symbiont in S. lupi that is closely related to Comamonas species (Brukholderiales: Comamonadaceae) of the beta-proteobacteria. Its DNA was detected in eggs, larvae and adult stages of S. lupi. Using fluorescent in situ hybridization technique, we localized Comamonas sp. to the gut epithelial cells of the nematode larvae. Specific PCR enabled the detection of this symbiont's DNA in blood obtained from dogs diagnosed with spirocercosis.

Conclusions

The discovery of a new Comamonas sp. in S. lupi increase the complexity of the interactions among the organisms involved in this system, and may open innovative approaches for diagnosis and control of spirocercosis in dogs.

Characterization of Onthophagus sellatus as the major intermediate host of the dog esophageal worm Spirocerca lupi in Israel

Spirocerca lupi is a parasitic nematode of dogs, that causes significant morbidity and mortality. Its intermediate hosts in Israel have never been described. The aim of this study was therefore to identify the intermediate hosts of S. lupi in Israel and to describe their abundance and annual infection rate with the nematode, in different microenvironments (i.e., the effects of irrigation and shade) in an endemic area. Dog dung pads were collected every 2 months from two different public parks for 1 year. Dung beetles were identified to the species level in infested dog feces and were examined for the presence of S. lupi larvae through dissection. The Scarabid beetle Onthophagus sellatus was the most abundant dung beetle species in dog dung pads and the only one infected with S. lupi larvae. The minimal period for development of the S. lupi L3 infective stage was 7 days. Significant differences were observed between the two different microenvironments and along the year. The highest risk for infection of dogs with the nematode was during the summer, in an irrigated, shady microenvironment.

Impaired nocifensive behaviours and mechanical hyperalgesia, but enhanced thermal allodynia in pituitary adenylate cyclase-activating polypeptide deficient mice

Pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) and its receptors (PAC1 and VPAC) have been shown in the spinal dorsal horn, dorsal root ganglia and sensory nerve terminals. Data concerning the role of PACAP in central pain transmission are controversial and we have recently published its divergent peripheral effects on nociceptive processes. The aim of the present study was to investigate acute somatic and visceral nocifensive behaviours, partial sciatic nerve ligation-evoked chronic neuropathic, as well as resiniferatoxin-induced inflammatory thermal and mechanical hyperalgesia in PACAP deficient (PACAP(-/-)) mice to elucidate its overall function in pain transmission. Neuronal activation was investigated with c-Fos immunohistochemistry. Paw lickings in the early (0-5 min) and late (20-45 min) phases of the formalin test were markedly reduced in PACAP(-/-) mice. Acetic acid-evoked abdominal contractions referring to acute visceral chemonociception was also significantly attenuated in PACAP knockout animals. In both models, the excitatory role of PACAP was supported by markedly greater c-Fos expression in the periaqueductal grey and the somatosensory cortex. In PACAP-deficient animals neuropathic mechanical hyperalgesia was absent, while c-Fos immunopositivity 20 days after the operation was significantly higher. In this chronic model, these neurons are likely to indicate the activation of secondary inhibitory pathways. Intraplantarly injected resiniferatoxin-evoked mechanical hyperalgesia involving both peripheral and central processes was decreased, but thermal allodynia mediated by only peripheral mechanisms was increased in PACAP(-/-) mice. These data clearly demonstrate an overall excitatory role of PACAP in pain transmission originating from both exteroceptive and interoceptive areas, it is also involved in central sensitization. This can be explained by the signal transduction mechanisms of its identified receptors, both PAC1 and VPAC activation leads to neuronal excitation. In contrast, it is an inhibitory mediator at the level of the peripheral sensory nerve endings and decreases their sensitization to heat with presently unknown mechanisms.

The development of a molecular approach for coprodiagnosis of Toxoplasma gondii

Copro-diagnostic methods for Toxoplasma gondii infected cats have been traditionally based on the identification of oocysts by light microscopy or by bioassays. The first method is not sensitive and also unable to differentiate between Toxoplasma oocysts from other coccidian parasites in cats, and the second is cumbersome, time consuming and expensive. We have adapted a polymerase chain reaction (PCR) method to detect T. gondii oocyst DNA in fecal samples. Oocysts were successfully disrupted by freeze thawing coupled with mechanical means, and DNA extraction was subsequently accomplished. The test, based on amplifying a 529 bp repeated sequence, proved sensitive for detecting 1-2 oocysts in 200 microg of stool sample. The test specificity was established by showing that DNA from other cat coccidia tested negative. Specificity was reconfirmed by Southern hybridization of the PCR products with a specific probe. Of 122 stool samples from Jerusalem cats surveyed for the presence of Toxoplasma oocysts, 11 were found positive by PCR while none was detected by microscopy.

Emergence of distinct genotypes of Cryptosporidium parvum in structured host populations

Cryptosporidium parvum is an apicomplexan parasite that infects humans and ruminants. C. parvum isolated from cattle in northeastern Turkey and in Israel was genotyped using multiple polymorphic genetic markers, and the two populations were compared to assess the effect of cattle husbandry on the parasite's population structure. Dairy herds in Israel are permanently confined with essentially no opportunity for direct herd-to-herd transmission, whereas in Turkey there are more opportunities for transmission as animals range over wider areas and are frequently traded. A total of 76 C. parvum isolates from 16 locations in Israel and seven farms in the Kars region in northeastern Turkey were genotyped using 16 mini- and microsatellite markers. Significantly, in both countries distinct multilocus genotypes confined to individual farms were detected. The number of genotypes per farm was higher and mixed isolates were more frequent in Turkey than in Israel. As expected from the presence of distinct multilocus genotypes in individual herds, linkage disequilibrium among loci was detected in Israel. Together, these observations show that genetically distinct populations of C. parvum can emerge within a group of hosts in a relatively short time. This may explain the frequent detection of host-specific genotypes with unknown taxonomic status in surface water and the existence of geographically restricted C. hominis genotypes in humans.

Spirocerca lupi in dogs: prophylactic effect of doramectin

Spirocerca lupi is primarily a parasite of dogs, which typically causes oesophageal nodules, aortic aneurysms, and spondylitis. This study investigated the efficacy of doramectin as a prophylactic agent for canine spirocercosis. Five beagle dogs were injected subcutaneously with doramectin (400 microg/kg on 3 occasions 30 days apart q30d), while 5 other beagle dogs served as untreated controls. All dogs were inoculated with 40 infectious S. lupi larvae (L3) one month after the last doramectin treatment. All control dogs and 4/5 treated dogs became infected. Two control dogs died of ruptured aortic aneurysms, while no deaths occurred in treated dogs. Oesophageal nodules appeared 40-103 day later in treated as compared to control dogs, and eggs appeared in the faeces 49-106 day later in treated as compared to control dogs. The mean faecal egg count on day 223 in the treatment group was reduced by 99.77%. All control dogs had thoracic radiographic changes during the study, while only 2/5 study dogs showed radiographic changes. This study shows that although doramectin did not entirely prevent canine spirocercosis it reduced the clinical signs associated with infection and delayed and reduced egg output.

Controlling the onset of natural cryptosporidiosis in calves with paromomycin sulphate

A prospective, controlled-blind field trial was conducted to evaluate the efficacy and safety of paromomycin sulphate, given for 10 days from birth, in preventing natural cryptosporidiosis in calves. In the untreated control group, oocyst shedding and diarrhoea followed the pattern that had occurred on the farm before the trial, consistent with a perinatal infection, whereas in the treated group, the prepatent period was significantly longer than in the control group (P < 0.01) and oocyst shedding and diarrhoea started only after the drug was withdrawn. However, the regimen did not reduce the incidence of disease in the treated group.

Disseminated eosinophilic disease resembling idiopathic hypereosinophilic syndrome in a dog

True idiopathic hypereosinophilic syndrome has been described in human beings and cats, but not in dogs. The syndrome is characterised by prolonged unexplained peripheral mature eosinophilia, the infiltration of many organs by eosinophils, organ dysfunction and a fatal outcome. This paper describes an idiopathic disseminated eosinophilic disease in a dog involving various organs, manly the heart and the lungs, accompanied by a leukemoid eosinophilic response, and a fatal outcome. The histopathological findings included the infiltration of the myocardium, lung parenchyma, liver, spleen, lymph nodes and skeletal muscles with eosiniphils.

Antibodies to selected canine pathogens and infestation with intestinal helminths in golden jackals (Canis aureus) in Israel

Blood and fecal samples, collected from 46 healthy adult free-ranging golden jackals captured in two different locations in Israel, were examined. A serological Study was conducted to investigate the prevalence of circulating antibodies reacting with four common canine pathogens: canine distemper virus (CDV), canine parvovirus (CPV), Ehrlichia canis and Leishmania infantum. Faecal flotation and haematological tests were also performed. The seroprevalence of CPV, E. canis, CDV, and L. infantum were 72.3% (34/47), 54.3% (25/46), 52.2% (24/46), and 6.5% (3/46) respectively. Faecal flotation tests revealed a high prevalence of Ancylostoma caninum (13/17, 76%) and a low prevalence of Dipilidium caninum infestation. Examination of blood smears revealed Hepatazoon canis gamonts in one jackal. Golden jackals are among the most common free-ranging carnivores in Israel and neighboring countries. Their habitats are in proximity to densely populated areas and they bear close phylogenic relation to the domestic dog. These facts, combined with the high prevalence of the jackals' exposure to the major canine pathogens demonstrated in this study, suggest that they may serve as a reservoir for the transmission of certain diseases to domestic dogs.

Yeasts in the gastrointestinal tract of preweaned calves and possible involvement of Candida glabrata in neonatal calf diarrhea

To examine the possibility of a mycotic involvement in neonatal calf diarrhea (NCD) the presence of fungi was assessed in (a) the intestinal contents of dead calves and fecal samples submitted for routine laboratory examination, (b) fecal specimens, sampled once in winter and once in summer, of calves raised on 2 farms with different management systems, and (c) mucosal scrapings of various segments of the digestive tract of a diarrheic calf, massively shedding Candida glabrata. C. glabrata was the most prevalent fungal species isolated from the routine samples. It was the only fungus which was shed by the calves on the 2 farms, for continuous, more or less prolonged periods, but exclusively in the winter months. Diarrhea and C. glabrata shedding seemed to be associated. C. glabrata colonized the abomasum (the functional equivalent of the monogastric stomach) but not the other segments of the digestive tract of the euthanized calf. Based on the findings of this study it seems that while some yeast species may be considered as commensals of the digestive tract of calves, and consequently their isolation from intestinal contents or fecal samples has no clinical significance, others, such as C. glabrata may be involved in enteric pathogenic processes. Moreover, characteristics of the culture, previous chemotherapeutic treatments, the animal's age and possibly climatic conditions should be taken into account before deciding on the fungal isolate's clinical relevance. Determination of mycotic involvement in NCD by routine mycological examination of intestinal contents and fecal samples of diarrheic calves may be useful to avoid unnecessary and potentially harmful antibacterial therapy.

Sudden death due to Paragonimus kellicotti infection in a dog

A sudden death due to Paragonimus kellicotti infection in a dog that had had no previous clinical signs of illness until the day of admission to the veterinary hospital is documented. The clinical, haematological and biochemical abnormalities, as well as postmortem findings, are presented. This report represents the first case of canine paragonimiasis in Israel, and discusses the possibility of this fluke becoming established in the Middle East.

The influence of aestivation in land snails on the larval development of Muellerius cf. capillaris (Metastrongyloidea: Protostrongylidae)

The larval development of Muellerius cf. capillaris in aestivating Trochoidea seetzenii and Theba pisana was delayed: in the first snail 82% of the parasites remained as second-stage larvae (L2) after as much as 90 days, and in the second snail 60% remained as L2 after 50 days. Reactivation of T. seetzenii after 59 days of aestivation caused the larvae to develop to the third stage (L3). The number of recovered larvae among T. seetzenii was consistently higher in active vs aestivating snails (P < 0.05). Such differences were not evident among T. pisana (P > 0.05). In active T. pisana, larval development was faster than in active T. seetzenii, whereas there were no such differences between aestivating snails of these 2 species. Aestivating infected T. seetzenii had lower body weights than same-size active non-infected, as well as infected snails. Aestivating infected T. pisana were not weighed, but they too exhibited poor body condition.

Spirocerca lupi infection in the dog: aberrant migration

The nematode Spirocerca lupi (S. lupi), a parasite of dogs and other carnivores, affects mainly the esophagus and the aorta leading to gastrointestinal, respiratory, and circulatory signs. Aberrant migration of the worm to unusual anatomical structures, especially the thoracic cavity, resulting in atypical clinical signs is being reported more frequently. Aberrant migration of S. lupi is reviewed, and two such cases (i.e., migration to the heart, causing an aortico-pulmonary "window-like" opening, and to a subcutaneous abscess in the caudal thoracic region) are presented.

Cloning and characterization of the SmIMP25 integral membrane protein of the parasitic helminth Schistosoma mansoni

The cDNA and genomic clones encoding a 25 kDa integral membrane protein, termed SmIMP25, were isolated from Schistosoma mansoni. The 2.2 kb SmIMP25 mRNA was found in all developmental stages of the parasite tested: miracidium, sporocyst, cercaria and adult worm. The SmIMP25 gene is at least 16 kb long and it is split by four introns ranging in size from 36 bp to > or = 9 kb. Excluding the introns, the gene and the cDNA show 100% sequence identity. The cDNA has an open reading frame encoding a protein 223 amino acids long. The predicted sequence reveals a distinct hydrophobic domain of 20 amino acids located 12 residues from the carboxyl-terminal end. The properties of this domain (marked hydrophobicity, size, flanking by charged residues and C-terminal location) are typical of the transmembrane segments of integral membrane proteins. The presence of three potential N-glycosylation sites is also consistent with membrane proteins that are often glycosylated at the extracellular domain. Accordingly we propose that SmIMP25 is an integral membrane protein in which residues 1-191 are extracellular, residues 192-211 comprise the hydrophobic domain that spans the membrane, and residues 212-223 are intracellular. The SmIMP25 was synthesized as a fusion protein in bacteria and antibodies were elicited in rabbits. Antibodies against SmIMP25 specifically precipitated a 25 kDa protein from cell-free products programmed by schistosome mRNA, in agreement with the size of the protein predicted from the cDNA sequence. Immunofluorescence studies showed SmIMP25 on the surface of the parasite. Surface molecules expressed at the host-parasite interface are likely to provide information on host parasite relationship and may serve as targets for protective immunity.

A case of natural hydatidosis in a baboon

Four large and several smaller cysts of Echinococcus granulosus were found in the liver of a baboon submitted for necropsy. Three of the large cysts had an atypical structure and were packed with a semi-solid mass of collapsed daughter cysts, small cysts containing fluid and involuted membranes. This atypical structure has been reported previously though only in baboons.

The effect of oxytetracycline treatment on immunity induced by Anaplasma centrale

Calves vaccinated with Anaplasma centrale were treated with 20 mg/kg of long-acting oxytetracycline (OTC/LA) before or simultaneously with vaccination or up to seven months later. Of 40 animals given one or two of OTC/LA from 3 to 13 days before vaccination, 23 become patent after vaccination, with an average prepatent period almost twice as long as that in non-treated vaccinated controls. Upon challenge with 2 x 10(8) A. centrale per dose all 17 previously non-patent calves showed average maximum parasitemias of 2 to 3.8%. Out of 30 calves treated with two to four doses of OTC/LA from one to four weeks after vaccination, 29 remained negative for A. centrale and reacted to challenge infection with average maximum parasitemias of 6.9-7.8%. Five out of 10 calves receiving OTC/LA simultaneously with the vaccination, and all of a separate group of 10 calves treated with a single dose seven days after vaccination, become patent an average of 51.6 and 63.5 d, respectively, after vaccination. Upon challenge, the five previously non-patent calves showed an average of 5.2% maximum parasitemia. In all groups, only rare parasites were seen in previously patent calves after challenge. Thirty calves treated with 2-4 doses of OTC/LA about six months after vaccination showed no or only a few parasites upon challenge. The above results show that treatment with single or multiple doses of OTC/LA a few weeks before or after administration of live A. centrale vaccine can interfere with elaboration of immunity.

Schistosoma mansoni: stage-specific expression of muscle-specific genes

It was previously shown that an antigen preparation termed 9B obtained from Schistosoma mansoni cercarial extracts partially (34%) protects mice from challenge infection with cercariae (R. Tarrab-Hazdai et al., J. Immunol. 135, 2772, 1985). To characterize some of the proteins which comprise this preparation, rabbit antibodies to the 9B antigen preparation were used to screen cDNA libraries of cercariae and adult worms. We isolated and sequenced cDNA clones encoding three proteins: calcium-binding protein, paramyosin, and myosin. The calcium-binding protein was previously shown to be expressed in cercariae but not in sporocysts or adult worms (D. Ram et al., Mol. Biochem. Parasitol. 34, 167, 1989). Northern blots showed the presence of paramyosin and myosin mRNAs in sporocysts and adult worms but not in cercariae. Antibodies to paramyosin detected the protein in sporocysts and adult worms as well as in cercariae. These findings explain, in part, the protective activity of the 9B antigen preparation against challenge infection.

Rapid changes in the expression of a gene encoding a calcium-binding protein in Schistosoma mansoni

Genes expressed in a stage-specific manner may help us understand the molecular events controlling the complex life cycle of schistosomes. cDNA and genomic clones encoding a calcium-binding protein (CaBP) were obtained from cercariae and their sequence determined. The encoded protein (69 amino acids long) shows clear resemblance to the domain structure and organization of CaBP molecules. It contains two typical calcium-binding loops, the distance between which is identical to the length conserved in other CaBP molecules. In addition, the schistosome CaBP shows Ca2+-dependent electrophoretic mobility (increased with Ca2+-ions and decreased with EGTA). Northern blots revealed expression of the CaBP gene in cercariae but not in sporocyst or worm (developmental stages preceding and following cercaria). The preferential expression of this CaBP in the cercaria raises questions as to what cercaria-specific function(s) it performs. The structure of the gene is similar to that in other eukaryotes, and one intron interrupts the coding sequence. The region of the cap site was determined, and there was no evidence of the spliced leader sequence found in the mRNAs of other parasites. The CaBP reveals a rapid change in gene expression, since the mRNA is missing in the parasite residing in infected snails, but is readily detected in cercariae 1 h after shedding. We identified other genes which are turned on (like the CaBP) or shut off within the short period of transition from cercariae in the snail to free-swimming cercariae.

Use of long-acting oxytetracycline in the immunisation of cattle against Babesia bovis and B bigemina

Forty Friesian one-year-old calves were vaccinated simultaneously with live Babesia bovis and B bigemina vaccines. Three groups of 10 calves each were treated with two, three or four doses of 20 mg kg-1 long-acting oxytetracycline (OTC/LA) at six- to seven-day intervals starting from day 6 after vaccination. Ten animals remained untreated. The treated calves showed considerably fewer days of patency and higher packed cell volumes than the vaccinated untreated calves. All calves developed serum antibodies to both parasites following vaccination. Five months later the 40 vaccinated and 30 new calves were challenged with syringe-transferred virulent parasites of both species. The vaccinated calves showed no parasites or clinical manifestations while calves of the new group exhibited severe clinical babesiosis. These results show that when OTC/LA is administered following anti-babesial vaccination, parasitaemia and red blood cell destruction are significantly reduced without, however, inhibiting the development of immunity.

Mitigation of the response of Friesian calves to live Babesia bovis vaccine by treatment with long acting oxytetracycline

Forty 11- to 13-month-old Friesian calves were inoculated with live Babesia bovis vaccine. Twenty of the calves were treated with long acting oxytetracycline seven and 15 days after receiving the vaccine. Parasites were detected in nine of the treated calves compared with all 20 of the untreated control group. Treated calves were less febrile and had higher packed cell volumes than control animals. All calves from both groups developed a considerable antibody titre to B bovis. It appears that long acting oxytetracycline can mitigate the response of sensitive cattle breeds to live antibabesial vaccine and prevent damage caused by excessive multiplication of B bovis parasites.