Recovery Of Parasites Research Articles

Pathogenic Microbiological Flora Recovered From Ear, Nose And Throat Specimens In A Regional Hospital In Kosovo

to investigate the recovery of pathogenic bacteria, fungi and parasites isolated from ear, nose and throat specimens in large population group in a secondary health care institution. retrospective study results of all microbiologic cultures submitted from the outpatient clinic of a large, secondary health care practice, for the time period January 2001 until December 2005 were identified from a microbiologic specimen database. The results from these cultures were entered into a database, tabulating site from which the culture was taken, from whom the material was sent and the type of organism recovered. from a total of 17,362 specimens, 88% results in the normal bacterial flora. Remaining 12% were pathological bacterial, fungal and parasite flora: 1218 from ear specimens, 376 from nose and. 474 from throat specimens. In 40% of cases material was sent by primary health care provider, in 52% of cases material was taken during systematic screening and only in about 8% the material was sent from an ENT specialist. the most frequent pathogens isolated from ear specimens are Staphylococcus saprophiticus and aureus, 24.6 and 17.7%, followed by Pseudomonas auriginosa in 13.2%; from nose specimens the most often isolated pathogenic bacteria is Staphylococcus aureus in 52.4%, Streptococcus spp. in 16% and Branhamella in 13% of nose specimens. From the throat specimens Staphylococcus aureus in 48.7%, Enterococcus in 13.3%, Streptococcus beta-haemolyticus gr. A in 11.8% and Streptococcus beta-haemolyticus gr. B in 8.4% of cases. Staphylococcus spp, Pseudomonas, Escherichia and Streptococcus spp. are leading pathogens from ear, nose and throat specimens, so further investigation on appropriate antibiotics use and bacterial resistance will be welcome.

Multistate Evaluation of an Ultrafiltration-Based Procedure for Simultaneous Recovery of Enteric Microbes in 100-Liter Tap Water Samples

Ultrafiltration (UF) is increasingly being recognized as a potentially effective procedure for concentrating and recovering microbes from large volumes of water and treated wastewater. Because of their very small pore sizes, UF membranes are capable of simultaneously concentrating viruses, bacteria, and parasites based on size exclusion. In this study, a UF-based water sampling procedure was used to simultaneously recover representatives of these three microbial classes seeded into 100-liter samples of tap water collected from eight cities covering six hydrologic areas of the United States. The UF-based procedure included hollow-fiber UF as the primary step for concentrating microbes and then used membrane filtration for bacterial culture assays, immunomagnetic separation for parasite recovery and quantification, and centrifugal UF for secondary concentration of viruses. Water samples were tested for nine water quality parameters to investigate whether water quality data correlated with measured recovery efficiencies and molecular detection levels. Average total method recovery efficiencies were 71, 97, 120, 110, and 91% for phiX174 bacteriophage, MS2 bacteriophage, Enterococcus faecalis, Clostridium perfringens spores, and Cryptosporidium parvum oocysts, respectively. Real-time PCR and reverse transcription-PCR (RT-PCR) for seeded microbes and controls indicated that tap water quality could affect the analytical performance of molecular amplification assays, although no specific water quality parameter was found to correlate with reduced PCR or RT-PCR performance.

Larval viability and serological response in horses with long-term Trichinella spiralis infection

The horse is considered an aberrant host for the nematode parasite Trichinella spiralis, and many aspects of the biology and epidemiology of Trichinella infection in the horse are poorly understood. It has been reported that experimentally-infected horses produce a transient serological response to infection and that muscle larvae are cleared more rapidly than in parasite-adapted hosts such as the pig and humans. However, limited numbers of animals have been studied, and both the longevity of larvae in horse musculature and the immune response to Trichinella larvae remain unclear. In this study, we infected 35 horses with 1000, 5000, or 10,000 T. spiralis muscle larvae and followed the course of infection for 1 year, assessing larval burdens in selected muscles, the condition and infectivity of recovered larvae, and the serological response of infected horses. The results demonstrated that T. spiralis establishes infection in horses in a dose dependent manner. Anti- Trichinella IgG antibodies peaked between weeks 6–10 post-inoculation. Viable, infective larvae persisted in horse musculature for the duration of the study (12 months), and exhibited no apparent reduction in muscle burdens over this period. Encapsulated larvae showed no obvious signs of degeneration in histological sections. Larval capsules were surrounded by infiltrates consisting of mature plasma cells and eosinophils. Macrophages were notably absent. Given the lack of a detectable serological response by 26 weeks p.i. and the persistence of infective muscle larvae for at least 1 year, parasite recovery methods are currently the only suitable detection assays for both meat inspection and epidemiological studies of Trichinella infection in the horse.

Genetic basis of the resistance to Strongyloides venezuelensis (Nematoda, Rhabdiasidae) infection in mice (Mus musculus)

We investigated the resistance to Strongyloides venezuelensis primary infection of mice strains NIH (resistant) and C57BL/6 (susceptible) and the F1 and F2 offspring of crosses between these strains. The mice were infected with 2000 larvae and seven days later were sacrificed for parasite recovery and counting. There was no statistically significant (p > 0.05) sex effect on resistance. The F1 mice showed an intermediate mean number of parasites as compared to the parental NIH and C57BL6 strains. Out of 400 F2 mice, the 10% most resistant mice were infected with 21 to 97 parasites, while the 10% most susceptible mice were infected with 1027 to 1433 parasites. We also found that F2 mice with black fur (n = 72), the same color as the C57BL/6 susceptible parental strain, were more susceptible than white (n = 104) or gray furred (n = 224) mice. It is conceivable that some genes determining coat color are located on the same chromosome as where genes controlling helminth resistance.

Host responses during experimental infection with Fasciola gigantica or Fasciola hepatica in Merino sheep : I. Comparative immunological and plasma biochemical changes during early infection

This study reports the early biochemical changes in plasma, comparative host-immune responses and parasite recovery data in Merino sheep during the first 10 weeks of infection with Fasciola gigantica and Fasciola hepatica. One group of sheep were uninfected, four groups of sheep received incremental challenge doses of F. gigantica metacercariae (50, 125, 225 and 400, respectively) and the sixth group was challenged with 250 F. hepatica metacercariae. At 10 weeks post infection (wpi), sheep challenged with F. hepatica showed the greatest fluke recovery (mean 119, range 84–166); a significantly higher biomass of parasites recovered (2.5-fold greater than the highest dose of F. gigantica); and a greater mean % parasite recovery (39.3%, range 27–55%) than any group challenged with F. gigantica. Within the groups dosed with F. gigantica a strong dose-dependent response was observed in both fluke recovery and fluke biomass with increasing dose of metacercariae. The mean % parasite recovery of F. gigantica infected groups 1–5 were 26, 23, 26 and 25%, respectively, suggesting a uniform viability of parasite establishment independent of infection dose. At 6 wpi, elevated levels of plasma GLDH were observed in the F. gigantica infected groups compared to the uninfected sheep ( p < 0.005) whereas the F. hepatica challenged group had four-fold higher levels of GLDH compared to the F. gigantica infected group ( p < 0.001). Elevated levels of GGT as an indicator of epithelial damage in the bile duct was only seen in the group challenged with F. hepatica at 10 wpi when it rose from below 100 IU/l to approximately 250 IU/l ( p < 0.0001) whereas no detectable increase in GGT was observed in any of the groups challenged with F. gigantica. The white blood cell response to F. hepatica infection was biphasic with the initial peak at 4 wpi and a second peak at 9 wpi, corresponding to the period of migration of juvenile fluke in the liver and the time when adult flukes are migrating into the bile duct, respectively. This biphasic response was also evident in the changes in the eosinophil counts and serum haemoglobin levels. There was a trend toward higher parasite-specific IgG 2 titres in sheep infected with lower worm burdens, suggesting that higher F. gigantica or F. hepatica burdens suppress IgG 2 responses. The findings of this study suggest that, in early infection in a permissive host, F. hepatica appears to be more pathogenic than F. gigantica because of its rapid increase in size and the speed of its progression through the migratory phases of its life cycle.

Mites in the personal environment and their role in skin disorders.

An investigation into the incidence and distribution of‘ecroparasites'in the close personal environment of patients with chronic unexplained dermatoses is described. Acari were found in 356 samples from 124 of 253 (50%) patients investigated. The house dust mite Dermatophagoides pteronyssinus and related species accounted for 157 (44%) of the ‘parasites’ identified. The clinical and laboratory parasite recovery techniques are described and their limitations considered. The possible significance of the results is discussed and the need for further work emphasized.

Oesophagostomum dentatumandTrichuris suisinfections in pigs born and raised on contaminated paddocks

Transmission of Oesophagostomum dentatum and Trichuris suis was studied in outdoor reared pigs. Six farrowing paddocks were naturally contaminated in May to mid-June 2001 by experimentally infected seeder pigs. In early July 1 sow farrowed on each paddock and starting at week 3 post-partum (p.p.) the offspring was slaughtered serially every 2 weeks for parasite recovery. Faeces were collected regularly for parasite egg counts and acid-insoluble ash (AIA) content as an indicator of geophagy. Weaning took place at week 7 p.p. by removing the sow. Paddock infection levels were estimated in mid-June (O. dentatum) and late November (O. dentatum and T. suis) using helminth-naïve tracer pigs. Soil and vegetation samples were collected regularly. Despite a high initial contamination by the seeder pigs, O. dentatum paddock infectivity was negligible to low throughout the raising of the experimental piglets, which had a slow accumulation of nodular worms ending with a mean of 422 worms/pig at week 19 p.p. As only few eggs developed to infectivity overall T. suis transmission was minimal. The first T. suis were recovered at week 11 p.p. and the highest mean burden of 21 worms/pig was recorded at week 19 p.p. The experimental pigs initially had a high faecal level of AIA although it decreased over time. The results are discussed in relation to the biological characteristics of the 2 parasites and their occurrence in organic pig production.

Interleukin‐2‐Activated Natural Killer Cells May Have a Direct Role in the Control of Leishmania (Leishmania) amazonensis Promastigote and Macrophage Infection

To study the role of Natural Killer (NK) cells in Leishmania infection, peritoneal macrophages from BALB/c mice were infected with Leishmania (Leishmania) amazonensis promastigotes and incubated with interleukin-2 (IL-2)-activated NK (A-NK) cells at different ratios of A-NK cells to infected macrophages (5:1, 1:1, 0.2:1). The A-NK cells were added either together with the parasites (0-h group) or 24 h later (24-h group). Morphological studies of the cultures revealed predominance of parasitic debris within macrophages that were in close contact with A-NK cells and the decrease in parasite recovery was directly proportional to the A-NK cell concentration used. Interferon-gamma (IFN-gamma) and IL-12 were detected in the supernatant at levels proportional to the A-NK cell concentration used. No significant difference was observed between the groups with respect to NO levels in the culture supernatant. When A-NK cells were added directly to the L. (L.) amazonensis promastigote cultures, the parasite recovery decreased proportional to the number of A-NK cells added. In vivo studies demonstrated smaller lesion sizes in animals inoculated with both parasites and A-NK cells compared with parasites alone. Histopathology of the skin lesions from animals receiving A-NK cells together with the parasites showed moderate parasitism and a nodular inflammatory infiltrate formed by mononuclear cells and a few vacuolized macrophages. In contrast, animals inoculated only with the parasites showed a highly parasitized dermis with infiltration of intensely vacuolized macrophages. These results demonstrate the role of A-NK cells in parasite lysis and in resistance of macrophages to L. (L.) amazonensis in the early phase of infection.

Experimental treatments with diflubenzuron and deltamethrin of sea bass, Dicentrarchus labrax L., infected with the isopod, Ceratothoa oestroides

Summary Sea bass with approximate average weights of 5 and 20 g were treated against Ceratothoa oestroides infection with: (i) medicated pellets of diflubenzuron PC90 at a dosage of 3 mg kg−1 body weight (BW) per day for 14 days. Lice were counted at the beginning of treatment and 19 days after treatment. The drug cleared all lice in the treated group; in the control group, infection remained high 30 days after beginning the experiment. It was concluded that medicated pellets containing 3 mg kg−1 BW diflubenzuron effectively cleared pre-adult and adult stages of the isopod parasite over a 14-day period. No adverse effects were recorded in treated sea bass during the trials and no reinfection occurred 15 days after end of the treatment. (ii) Deltamethrin by means of bath treatments in infected sea bass kept in experimental tanks at 20°C. Before treatment, toxicity on healthy fish was preliminarily assessed by testing five fish from each size group at concentrations of 30, 10, 5, 3, 1, 0.1, 0.05 and 0.01 mg L−1 for 30 min. The therapeutic concentrations tested were: 10, 5, 3, 0.15, 0.1, and 0.05 μg L−1 and assessed at 1, 24 and 48 h. Best results were achieved with the 10 μg L−1 (0.01 mg L−1) dose, where prevalence was reduced from 100 to 0% over 24 h in both large and small fish. No parasite recovery was observed at 48 h. The dose of 5 μg L−1 reduced prevalence from 100 to 11.7% and to 0% for small and large fish, respectively. Finally, with the 3 μg L−1 dose, prevalence was reduced from 100 to 37.5% (small fish) and to 13.3% (large fish). Lower doses were ineffective on the parasites at either 24 or 48 h.

Immunoglobulin E and eosinophil-dependent protective immunity to larval Onchocerca volvulus in mice immunized with irradiated larvae.

Mice immunized with irradiated Onchocerca volvulus third-stage larvae developed protective immunity. Eosinophil levels were elevated in the parasite microenvironment at the time of larval killing, and measurements of total serum antibody levels revealed an increase in the immunoglobulin E (IgE) level in immunized mice. The goal of the present study was to identify the role of granulocytes and antibodies in the protective immune response to the larval stages of O. volvulus in mice immunized with irradiated larvae. Immunity did not develop in mice if granulocytes, including both neutrophils and eosinophils, were eliminated, nor did it develop if only eosinophils were eliminated. Moreover, larvae were killed in naïve interleukin-5 transgenic mice, and the killing coincided with an increase in the number of eosinophils and the eosinophil peroxidase (EPO) level in the animals. To determine if EPO was required for protective immunity, mice that were genetically deficient in EPO were immunized, and there were no differences in the rates of parasite recovery in EPO-deficient mice and wild-type mice. Two mouse strains were used to study B-cell function; micro MT mice lacked all mature B cells, and Xid mice had deficiencies in the B-1 cell population. Immunity did not develop in the micro MT mice but did develop in the Xid mice. Finally, protective immunity was abolished in mice treated to eliminate IgE from the blood. We therefore concluded that IgE and eosinophils are required for adaptive protective immunity to larval O. volvulus in mice.

Characterisation of Toxoplasma gondii engineered to express mouse interferon-gamma

Recent studies have shown the feasibility of using Toxoplasma gondii as an expression system for heterologous protein. For better understanding of the mechanism of interferon-gamma (IFN-γ) dependent immunity to T. gondii, the parasites were stably transfected with IFN-γ gene, under control of the GRA1 promoter. Immunofluorescence analyses showed that recombinant mouse IFN-γ localised to discrete punctuate structures consistent with dense granules and secreted into the vacuolar space. The production of IFN-γ was detectable in both extracellular parasites and the parasite-infected cells. Growth of the recombinant parasites was inhibited in the mouse macrophage cell line (J774A.1 cells), but not in monkey kidney adherent fibroblasts (Vero cells), demonstrating the species-specificity of IFN-γ. Addition of anti-mouse IFN-γ antibody resulted in growth recovery of the recombinant parasites, suggesting that IFN-γ, secreted from the parasitised host cells across the parasitophorous vacuole membrane, acted in a paracrine manner. Reverse transcription (RT)-PCR analysis revealed significant expression of inducible nitric oxide synthase mRNA and high levels of nitric oxide production in recombinant parasite-infected J774A.1 cells. A competitive inhibitor of the l-arginine-dependent effector pathway, N G-monomethyl- l-arginine, inhibited the reduction of recombinant parasite growth in J774A.1 cells. Taken together, our data suggest that the T. gondii expression system may provide a new tool for cytokine gene expression and that parasites engineered to express a cytokine gene may be rationally designed for use in studies on immune responses to T. gondii.

Evaluation of formalin-acetone sedimentation in the concentration of stool for intestinal parasites.

Formalin-acetone sedimentation was compared with the formalin-ether method for the concentration of stool for intestinal parasites. Of 80 stool specimens, 45 (56.25%) were positive for parasites by the formalin-acetone method. The figures for the two methods were formalin-ether 35 (43.75%) and for the direct lacto-phenol cotton blue wet mount method 17 (21.25%). There was no statistically significant difference in the parasite recovery rate between the two methods. Acetone is more stable, safer, and a cheaper fat solvent and promises to be a useful alternative to ether.

Oral transfer of adult Ancylostoma ceylanicum hookworms into permissive and nonpermissive host species.

Syrian hamsters become anemic and exhibit delayed growth following oral infection with third-stage Ancylostoma ceylanicum hookworm larvae. Here we describe experiments designed to determine the feasibility of adult worm transfer (AWT) between hosts, a technique that would facilitate the specific study of bloodfeeding hookworms in vivo without prior exposure of the host to larva-specific antigens, permit the ex vivo manipulation of adult parasites prior to reimplantation, and also allow for cross-species transfer of worms. Weanling hamsters given an oral AWT of 40 or 60 mixed-sex A. ceylanicum worms rapidly developed anemia; in the higher-dose group, hemoglobin levels declined from prechallenge levels by 44% within 4 days following AWT. Long-term survival of transferred worms was demonstrated by recovery of parasites from the intestines 42 days after AWT. AWT hamsters acquired humoral immune responses against soluble adult hookworm extracts and excretory-secretory products that were comparable in magnitude to those of animals given a typical infection with larvae. In AWT experiments employing the nonpermissive murine model, C57BL/6 mice given adult worms rapidly became anemic and lost weight in a manner similar to AWT hamsters. Infection of additional mouse strains demonstrated that while C57BL/10 and CD-1 mice also developed anemia following AWT, BALB/c mice were resistant. The technique of AWT to mice may further our understanding of hookworm pathogenesis by allowing the study of adult hookworm infections in a species with well-characterized genetics and an abundance of available reagents.

Estacionalidad de parásitos intestinales en suelos periurbanos de la ciudad de Neuquén, Patagonia, Argentina

To determine the presence of eggs, larva, cysts and oocysts of intestinal parasites in the soil of a suburb of Neuquén city during 1 year in order to evaluate their seasonal fluctuations in relation to climatic data and soil characteristics in the studied area. A total of 107 soil samples were processed for parasite isolation by sedimentation and flotation methods during the four seasons of the year. Meteorological data were registered and physical, chemical and structural characteristics of the soil were analysed. About 28.9% of the soil samples were positive for at least one parasite form. Six protozoa species (cysts of Entamoeba sp., Enteromonas sp., Endolimax sp., Giardia sp., Iodamoeba sp. and coccidia oocysts) were recovered, but neither larvae nor eggs of human or animal helminths parasites were detected. The percentage of contaminated soil samples and the diversity of species showed a marked decrease in the warm and dry months of the summer. The soil was sandy, without vegetable cover, well drained, and with scarce organic matter content. The frequencies of parasite recovery and the number of species show seasonal fluctuations related to the rainfall. The importance of soil as a risk factor for the transmission of intestinal parasites in the studied area is conditioned by its structural characteristics, which prevent retaining the humidity, and by climatic variables. The interrelation of both factors determines unfavourable conditions that could explain the low level of contamination observed in soil as well as the absence of eggs and helminth larvae.

Parasites of stellate sturgeon (Acipenser stellatus) from south-west of Caspian Sea

Sturgeons are the most important fishes of Caspian Sea, but there are few reports about the pathogens of them in southern part of the Sea. in this survey, it has been attempted to indicate the parasite communities of Acipenser steflatus and their prevalence as well as their effects on the fish growth. In this survey 234 A. steflatus were caught from three different geographical locations including fisheries sections I. ii and a hatchery adjucent to Sephid Rud River (ill) in south -west of Caspian Sea (Guilan Province. iran).Common parasitology procedures were used for necropsy of the fish and recovery of parasites. The parasites were fixed in Buffererd Formalin (10%) and ethyl alcohol (70%), stained by Acetocarmine and then identified. Standard statistical computations (mean, Standard Deviation, range, prevalence and dominance) were calculated for the overall samples and for samples grouped by geographical location. The differences between groups defined by Z test and One Way Anova test (p<0.05). Nine different parasite species wererecovered from internal organs of the fishincluding Skrjabinopsoius semiarmatus (preva|ence= p = 43.15%). Leptorhynchoides plagicephaius (p = 20.18%). Cuculianus sphaerocephaius (,0:17.26%}, Eubothrium acipenserfnum (p=9.14%), Bothrimonus faflax (p = 4.47%), Eustrongylides excisus (larvae), Anisakis sp. (larvae), Amphilina foiiacea and Corynosoma strumosum. The prevalence and intensity of parasites in fisheries section of ii and III were more than section I. A direct relation was found between some parasites(especially 8 .semr'armatus) and size. The prevalence and intensity of some parasites in females were more than males and also it was found that there is a correlation between some parasites (especially 3. semiamiatus) and season. in this survey, again it was found that the internal parasites of A. steliatus in this area (south ~ west) are the same as northern part of Caspian Sea but the diversity of parasites was less than north. Furthermore, the diversity of parasites has been decreased in a period of time (compared with the first survey), though the prevalence and intensity of some (marine) parasites appears to be increased during this period. Keywords: Fish, sturgeon, Acipenser stellatus, parasite, Caspian Sea References Dogiel, V.A.; Bykhovskiy, B.E. (1939): The parasites of fishes of Caspian Sea; in: Parasitic nematodes of fresh water fishes of Europe; Moravec, F. (1994); Kluwer Academic Publishers 473 p. Dubinln, V.B. (1952). Parazitofauna molodi osetrovikh ryb Nizhnei Volgi. In: The fresh water fishes of Europe; HolciK, J. (1989), Vol.1, part.2, AULA-Veriag Weisbaden Publication. Emadi,H;(1996). The situation of catching and the reason of decreasing the sturgeons stock ; Journal of Abzyyan ,voI.1 , p.16-18; Iran, In Persian Goroi,A;(1995): Identification of blood andinternal parasites of A. persicus in southern part of Caspian Sea ; Journal of Fisheries Organization of Iran ; vol.1, pp.35; ln Persian . HolciK .J , (1989) , The fresh water fishes of Europe , Vol.1 , part.2 , AULA-Venag Weisbaden Publication , pp. 395-433 , 345-363 , 206-223 Mokhayer, B. (1972): Recherches sur le parasitisme des Esturgoens de la MerCaspienne Meridionale, These; Universite de Paris Moravec, F. (1994): Parasitic Nematodes of fresh watr fishes of Europe, Kluwer Academic publishers, pp. 172-173, 195- 198, 377-380, 396 -399 . Nechaeva, N.L.; (1964). Parazitofauna molodi osetrovikh ryb Kaspiisko — Kurinskogo rajona; In: The fresh water fishes of Europe; Ho|c1'K, J. (1989), Vol.1,part.2, AULA-Veriag Weisbaden Publication. Sattari, M. ( 1999). Parasites of sturgeons (Chondrostei: Acipenseridae ) from south -west part of Caspian Sea ; Thesis ;Faculty of veterinary medicine ; The University of Tehran ; lran ; p. 280 (In Persian). Skryabina, E.S. (1974): Helminths of Acipenserid Fishes; ln: Parasitic Nematodes of fresh watr fishes of Europe; Moravec, F. (1994); Kluwer Academic publishers, 473 p. Shulman , S.S.; (1954) :Obzor fauny parasitov osetrovikh ryb SSSR ; ln:The fresh water fishes of Europe ; Hoicil-<,J. (1989), vol.1 , part.2 , AULA-VerlagWeisbaden Publication .

The chitinase system from Trichomonas vaginalis as a potential target for antimicrobial therapy of urogenital trichomoniasis

Chitinolytic activities in Trichomonas vaginalis membrane extracts were assessed by assays of three enzyme systems: N-acetyl-β- D-hexosaminidase (NAHase), chitobiosidase and chitotriosidase. N-acetyl-β- D-hexosaminidase was the enzyme that showed the highest specific activity. After successive subcutaneous inoculations into mice and parasite recovery in culture, the enzyme activities increased significantly with the number of inoculations for up to eight passages. In addition, enzyme activities were maximum at the logarithmic phase of growth. Glycol chitin, a chitinase substrate, enhanced all chitinolytic activities by about 30% and a clear-cut correlation is shown between the capacity for erythrocyte lysis by parasites and NAHase expression. Chitobiosidase and chitotriosidase activities were both inhibited at 58% and 100%, respectively, by allosamidine, a chitinase inhibitor used at 3 μM, whereas NAHase activity was not affected. Seven putative NAHase inhibitors (compounds n, 1–7), ureido and thioureido derivatives of 2-amino-2-deoxy- D-glucose were evaluated and five of them had K i values in the range 30–70 μM. The most active compound (compound 6) was functionally competitive with respect to the substrate with a K i value of 30 μM. The IC 50 values of the most active compounds on T. vaginalis were in the range 62–85 μM. These results indicate that chitinases of T. vaginalis are involved in pathogenicity and they could be an interesting target for drugs since chitinase inhibitors also inhibit parasite growth.

Application of the novel fluorescent dye Beljian red to the differentiation of Giardia cysts

Beljian red (BR) is a novel long Stokes shift fluorescent dye that fluoresces orange when illuminated with UV or blue light. Due to its long Stokes shift, and the fact that it is excitable at 488 nm, BR has particular utility in multi-colour applications with short Stokes shift fluorophores such as fluorescein. Here we have demonstrated that BR can be used to discriminate Giardia cysts seeded into water samples from those naturally present in the sample. We show that the dye does not interfere with other staining methods such as DAPI, and is compatible with mAb-FITC staining in a multi-colour fluorescence technique. This should be useful in determining the specific recovery of protozoan parasites from environmental samples.

Seasonal transmission of gastrointestinal parasites of equids in southern Louisiana.

Parasite-naive pony foals were used as sentinels to monitor transmission of gastrointestinal parasites of equids in Louisiana during 4 seasons of the year. Two annual periods were studied, 1988-1989 and 1992-1993. Two or 3 foals each season were turned out to graze a contaminated pasture along with resident parasitized mares and their foals. After a grazing period of 8 wk, sentinel ponies were held in a parasite-free box stall for a period of 6 wk to allow parasites to develop, thus enhancing the evaluation of hypobiotic stages. Following this holding period, necropsies were performed for complete parasite recoveries. Data show that transmission of large and small strongyles occurs during all seasons in southern Louisiana, with highest levels of transmission occurring in the winter and only minimal transmission taking place in the summer. Numbers of mucosal cyathostomes, as well as total cyathostome numbers, were highest in the winter, and luminal cyathostome numbers were highest in the spring. Transmission of Anoplocephala perfoliata and Parascaris equorum occurred during all seasons of the year, although numbers of P. equorum were reduced in spring 1989 and 1993. Gasterophilus intestinalis instars were recovered from fall and winter sentinels only. Oxyuris equi L4 were found all seasons 1 yr, but only during the fall and winter of the final year.

Ecological influences on transmission rates of Ascaris suum to pigs on pastures

A study was conducted to determine the distribution and transmission rate of Ascaris suum eggs and Oesophagostomum dentatum larvae in a pasture/pig house facility, which during the preceding summer was contaminated with helminth eggs by infected pigs. In May, four groups of 10 helminth naı̈ve tracer pigs were exposed to fenced sections of the facility for 7 days and necropsied for parasite recovery 9–10 days later (trial 1). The highest rate of A. suum transmission (201 eggs per day) occurred in the pig house (A). On the pasture, egg transmission decreased with the distance from the house: 8 eggs per day in the feeding/dunging area (B); 1 egg per day on the nearest pasture (C); <1 egg per day on the distant pasture (D). Only a few O. dentatum infections were detected, indicating a poor ability of the infective larvae to overwinter. Soil analyses revealed that the highest percentage (5.8%) of embryonated A. suum eggs were in the house (A). Subsequently, the facility was recontaminated with A. suum eggs by infected pigs. A replicate trial 2 was conducted in the following May. A major finding was the complete reversal of egg distribution between the 2 years (trials 1 and 2). In contrast to previous results, the highest rates of transmission (569 and 480 eggs per day) occurred in pasture sections C and D, and the lowest transmission rates (192 and 64 eggs per day) were associated with the feeding/dunging sections and the house (B and A). Soil analyses again supported the tracer pig results, as the pasture sections had the highest concentrations of embryonated eggs. Detailed soil analysis also revealed a non-random, aggregated egg distribution pattern. The different results of the two trials may be due to the seasonal timing of egg deposition and tracer pig exposure. Many eggs deposited during the summer prior to trial 1 may have died rapidly due to high temperatures and dessication, especially when they were not protected by the house, while deposition in the autumn may have favored egg survival through lower temperatures, more moisture, and greater sequestration of eggs in the soil by rain and earthworms. The latter eggs may, however, not have become embryonated until turnout the next year. The results demonstrate that yearly rotations may not be sufficient in the control of parasites with long-lived eggs, such as A. suum, and that a pasture rotation scheme must include all areas, including housing.

Epidemiology of parasitic gastrointestinal nematode infections of ruminants on smallholder farms in central Kenya

In order to establish the infection pattern with gastrointestinal nematodes in ruminants in the central Kenya highlands, a study was carried out in 58 smallholder farms. The study involved monthly faecal examinations from sheep, goats and cattle and pasture sampling from eight communal grazing areas. Each month, six Dorper worm-free tracer lambs were introduced and four locally grazed cross-bred sheep were purchased for parasite recovery. The mean faecal egg counts (FEC) for cattle were low throughout the study period, whereas those for sheep and goats showed a seasonal pattern with high levels of infection occurring during the two main rainy seasons, especially in March, April and October. There were significant differences in egg counts over time and among farms. Haemonchus contortus was the most prevalent nematode in the tracer lambs whereas the previously exposed locally grazed sheep had significantly lower numbers of H contortus but significantly higher numbers ofTrichostrongylus species The highest levels of infection in the tracer lambs occurred in November 1995 and January, May and June 1996. Based on this study, it is now possible to explore the possibility of using strategic treatments for the control of parasitic gastroenteritis in this area of Kenya.