Neuromusculature of Gyrodactylus rysavyi, a monogenean gill and skin parasite of the catfish Clarias gariepinus

Phalloidin fluorescence technique, enzyme cytochemistry and immunocytochemistry in conjunction with confocal scanning laser microscopy were used for the first time to describe the nervous and muscle systems of the viviparous monogenean parasite, Gyrodactylus rysavyi inhabiting the gills and skin of the Nile catfish Clarias gariepinus. The body wall muscles are composed of an outer layer of circular fibres, an intermediate layer of paired longitudinal fibres and an inner layer of well-spaced bands of diagonal fibres arranged in two crossed directions. The musculature of the pharynx, intestine, reproductive tract and the most prominent muscles of the haptor were also described. Two characteristic muscular pads were found lying in the anterior region of the haptor in close contact with the hamuli. To each one of these pads, a group of ventral extrinsic muscles was connected. The role of this ventral extrinsic muscle in the body movement was discussed. The mechanism operating the marginal hooklets was also discussed. The central nervous system (CNS) consists of paired cerebral ganglia from which three pairs of longitudinal ventral, lateral and dorsal nerve cords arise. The nerve cords are connected at intervals by many transverse connectives. The CNS is better developed ventrally than dorsally or laterally and it has the highest reactivity for all neuroactive substances examined. Both the central and the peripheral nervous system (PNS) are bilaterally symmetrical. Structural and functional correlates of the neuromusculature of the pharynx, haptor and reproductive tracts were explained. The results implicated acetylcholine, FMRFamide-related peptides (FaRPs) and serotonin in sensory and motor function. The results were compared with those of the monogeneans Macrogyrodactylus clarii and M. congolensis inhabiting the gills and skin respectively of the same host fish C. gariepinus.

Natural infection by Paramphistomoidea Stiles and Goldberger, 1910 trematodes in wild Marsh Deer (Blastocerus dichotomus Illiger, 1815) from Sérgio Mottas's hydroelectric power station flooding area.

Studies on helminthfauna of marsh deer Blastocerus dichotomus Illiger, 1815 are rare, although helminthic diseases are an important cause of mortality in these animals. Fifteen male and female adult marsh deer from Sergio Motta's hydroelectric power station flooding area at Paraná River which died during the capture and quarantine procedures, between 1998 and 1999, were necropsied. Three trematodes species, Paramphistomum cervi, Balanorchis anastrofus and Zygocotyle lunatum, all belonging to superfamily Paramphistomoidea, were identified. The obtained trematodes were identified, counted and their respectives descriptors of infection were determined. All necropsied animals were infected by helminths. Paramphistomum cervi was the most prevalent species, while Zygocotyle lunatum was found in only one animal.

New species of Haplometroides (Digenea: Plagiorchiidae) from Phalotris nasutus (Gomes, 1915) (Serpentes, Colubridae)

A new species of Haplometroides (Digenea, Plagiorchiidae) is described from a specimen of Phalotris nasutus (Gomes, 1915) (Serpentes, Colubridae). The host snake was obtained in the municipality of Corumbá, Mato Grosso do Sul State, Brazil. Trematodes were recovered from esophagus, stomach, and small intestine of the host. The main characteristic of the new species is the vitellaria, which is intercecal, cecal, and extracecal in the preacetabular region. A key for identification of the species in Haplometroides is proposed. © American Society of Parasitologists 2007.

Experimental Bolbophorus damnificus (Digenea: Bolbophoridae) Infections in Piscivorous Birds

In order to determine potential definitive hosts of the digenetic trematode, Bolbophorus damnificus, two American White Pelicans (Pelecanus erythrorhynchos), two Double-crested Cormorants (Phalacrocorax auritus), two Great Blue Herons (Ardea herodias), and two Great Egrets (Ardea alba) were captured, treated with praziquantel, and fed channel catfish (Ictalurus punctatus) infected with B. damnificus metacercariae. Patent infections of B. damnificus, which developed in both American White Pelicans at 3 days post-infection, were confirmed by the presence of trematode ova in the feces. Mature B. damnificus trematodes were recovered from the intestines of both pelicans at 21 days post-infection, further confirming the establishment of infection. No evidence of B. damnificus infections was observed in the other bird species studied. This study provides further evidence that Double-crested Cormorants, Great Blue Herons, and Great Egrets do not serve as definitive hosts for B. damnificus.

Geographic Variation of Notified Ross River Virus Infections in Queensland, Australia, 1985-1996

The spatial and temporal variations of Ross River virus infections reported in Queensland, Australia, between 1985 and 1996 were studied by using the Geographic Information System. The notified cases of Ross River virus infection came from 489 localities between 1985 and 1988, 805 between 1989 and 1992, and 1,157 between 1993 and 1996 (chi2(df = 2) = 680.9; P < 0.001). There was a marked increase in the number of localities where the cases were reported by 65 percent for the period of 1989-1992 and 137 percent for 1993-1996, compared with that for 1985-1988. The geographic distribution of the notified Ross River virus cases has expanded in Queensland over recent years. As Ross River virus disease has impacted considerably on tourism and industry, as well as on residents of affected areas, more research is required to explore the causes of the geographic expansion of the notified Ross River virus infections.

Correcting for bias when estimating the cost of hospital-acquired infection : an analysis of lower respiratory tract infections in non-surgical patients

Hospital acquired infections (HAI) are costly but many are avoidable. Evaluating prevention programmes requires data on their costs and benefits. Estimating the actual costs of HAI (a measure of the cost savings due to prevention) is difficult as HAI changes cost by extending patient length of stay, yet, length of stay is a major risk factor for HAI. This endogeneity bias can confound attempts to measure accurately the cost of HAI. We propose a two-stage instrumental variables estimation strategy that explicitly controls for the endogeneity between risk of HAI and length of stay. We find that a 10% reduction in ex ante risk of HAI results in an expected savings of £693 ($US 984).

Economic evaluation and catheter-related bloodstream infections

Catheter-related bloodstream infections are a serious problem. Many interventions reduce risk, and some have been evaluated in cost-effectiveness studies. We review the usefulness and quality of these economic studies. Evidence is incomplete, and data required to inform a coherent policy are missing. The cost-effectiveness studies are characterized by a lack of transparency, short time-horizons, and narrow economic perspectives. Data quality is low for some important model parameters. Authors of future economic evaluations should aim to model the complete policy and not just single interventions. They should be rigorous in developing the structure of the economic model, include all relevant economic outcomes, use a systematic approach for selecting data sources for model parameters, and propagate the effect of uncertainty in model parameters on conclusions. This will inform future data collection and improve our understanding of the economics of preventing these infections.

Persistent chlamydial infections : role in inflammation and challenges for vaccine development.

The development of chlamydial vaccines continues to be a major challenge for researchers. While acute infections are the main target of vaccine development groups, Chlamydia is well known for its ability to establish chronic or persistent infections in its host. To date, little effort has focussed specifically on the challenges of vaccines to successfully combat the chronic or persistent phase of the disease and yet this will be a necessary aspect of any fully successful chlamydial vaccine. This short review specifically examines the phenomenon of chlamydial persistence and the unique challenges that this brings to vaccine development.

Spatial analysis of notified cryptosporidiosis infections in Brisbane, Australia

Purpose: This study explored the spatial distribution of notified cryptosporidiosis cases and identified major socioeconomic factors associated with the transmission of cryptosporidiosis in Brisbane, Australia. Methods: We obtained the computerized data sets on the notified cryptosporidiosis cases and their key socioeconomic factors by statistical local area (SLA) in Brisbane for the period of 1996 to 2004 from the Queensland Department of Health and Australian Bureau of Statistics, respectively. We used spatial empirical Bayes rates smoothing to estimate the spatial distribution of cryptosporidiosis cases. A spatial classification and regression tree (CART) model was developed to explore the relationship between socioeconomic factors and the incidence rates of cryptosporidiosis. Results: Spatial empirical Bayes analysis reveals that the cryptosporidiosis infections were primarily concentrated in the northwest and southeast of Brisbane. A spatial CART model shows that the relative risk for cryptosporidiosis transmission was 2.4 when the value of the social economic index for areas (SEIFA) was over 1028 and the proportion of residents with low educational attainment in an SLA exceeded 8.8%. Conclusions: There was remarkable variation in spatial distribution of cryptosporidiosis infections in Brisbane. Spatial pattern of cryptosporidiosis seems to be associated with SEIFA and the proportion of residents with low education attainment.

Continuous infusion of ticarcillin-clavulanate for home treatment of serious infections : clinical efficacy, safety, pharmacokinetics and pharmacodynamics

Continuous infusion (CI) ticarcillin–clavulanate is a potential therapeutic improvement over conventional intermittent dosing because the major pharmacodynamic (PD) predictor of efficacy of β-lactams is the time that free drug levels exceed the MIC. This study incorporated a 6-year retrospective arm evaluating efficacy and safety of CI ticarcillin–clavulanate in the home treatment of serious infections and a prospective arm additionally evaluating pharmacokinetics (PK) and PD. In the prospective arm, steady-state serum ticarcillin and clavulanate levels and MIC testing of significant pathogens were performed. One hundred and twelve patients (median age, 56 years) were treated with a CI dose of 9.3–12.4 g/day and mean CI duration of 18.0 days. Infections treated included osteomyelitis (50 patients), septic arthritis (6), cellulitis (17), pulmonary infections (12), febrile neutropenia (7), vascular infections (7), intra-abdominal infections (2), and Gram-negative endocarditis (2); 91/112 (81%) of patients were cured, 14 (13%) had partial response and 7 (6%) failed therapy. Nine patients had PICC line complications and five patients had drug adverse events. Eighteen patients had prospective PK/PD assessment although only four patients had sufficient data for a full PK/PD evaluation (both serum steady-state drug levels and ticarcillin and clavulanate MICs from a bacteriological isolate), as this was difficult to obtain in home-based patients, particularly as serum clavulanate levels were found to deteriorate rapidly on storage. Three of four patients with matched PK/PD assessment had free drug levels exceeding the MIC of the pathogen. Home CI of ticarcillin–clavulanate is a safe, effective, convenient and practical therapy and is a therapeutic advance over traditional intermittent dosing when used in the home setting.