Mode of action of lufenuron on larval cat fleas (Siphonaptera: Pulicidae)

Adult cat fleas, Ctenocephalides felis (Bouché), were fed suboptimal in vitro concentrations of lufenuron in blood to allow hatching of flea larvae for cytological study. At concentrations of 0.125, 0.25, and 0.5 ppm, larval hatch was 64, 15, and 4%, respectively. Larvae hatching from eggs laid by adults fed lufenuron at concentrations of 0.025, 0.08, or 0.125 ppm did not differ significantly from the control. However, many larvae from the 0.08-ppm group and higher concentrations died during the 1st instar. Examination of these larvae revealed that they were dying from desiccation caused by bleeding from microscopic lesions in the cuticle or the inability to complete the molt to the next instar. Electron micrographs showed that lufenuron often disrupted formation of the endocuticle resulting in the deposition of an amorphous mass of randomly oriented chitin microfibrils. Other larvae formed normal endocuticle but were unable to digest the old endocuticle or produce new procuticle after apolysis. Failure of larvae to digest old cuticle or form new cuticle was caused by degeneration of the epidermal cells needed for the synthesis of molting fluid and chitin.     

Analysis of 36-kilodalton protein (PapA) associated with the bacteriophage particle of Bartonella henselae

A library of Bartonella henselae DNA was screened with antibody raised to the bacteriophage particle associated with this organism. A clone was isolated that expresses a 36-kD protein (termed PapA for particle-associated protein) when examined by immunoblot analysis using antibody raised to the particle. Southern blot hybridization indicates that the gene is present on the bacterial chromosome and packaged into the 14-kb particle-associated DNA. A papA-specific probe hybridized to multiple bands of B. henselae genomic DNA digested with several different restriction endonucleases. Thus, the gene is present in multiple copies on the genome or in different arrangements within a given population of B. henselae cells. The gene coding for PapA has been sequenced and codes for a 326-amino-acid protein with a deduced molecular weight of 36,161 daltons. The deduced protein shows 33.3% identity over a 108-amino-acid sequence with the P-min gene product of Escherichia coli. P-min is partially located within the invertible P region of the excisable element e14, found on the E. coli chromosome. Taken together, these results suggest that papA is present on a mobile genetic element of the B. henselae genome and is also packaged into the bacteriophage particle.     

Lack of bactericidal effect of antibiotics except aminoglycosides on Bartonella (Rochalimaea) henselae

Bartonella (Rochalimaea) henselae is a cause of peliosis hepatis and bacillary angiomatosis, and one of the putative agents of cat scratch disease. Specific therapy for B. henselae infections is not available. Treatment failures and relapses are frequent, especially following brief antibiotic courses, and this contrasts with the in-vitro susceptibility of B. henselae to most antibiotics. We decided to test the antibiotic susceptibility of B. henselae associated with murine macrophage-like cells (P388 D1) and a human endothelial cell line. We carried out a bactericidal assay in this model and in axenic broth. In both models, only aminoglycosides were bactericidal. These results suggest that aminoglycosides may be effective in the treatment of B. henselae infections.     

Ecology of flea groups of the species conformis (Siphonaptera: Pulicidae: Xenopsylla) of the fauna of Russia and adjacent countries (review)

Within the boundaries of the former USSR, the northern part of the conformis group distribution is located. It spreads over the arid regions of the Trans-Cacucasus, Pricaspijckaja lowland, Kazakhstan and Middle Asia. In this area 10 species and subspecies occur. They are mainly parasites of gerbillins. Unlike many other Siphonaptera the conformis fleas, when in the host's home, do not concentrate in the nest but inhabit the passages of burrow and food chambers throughout the year. On this reason the preimaginal development and existence of the adults take place not at the temperature of the habitable nest, which is heated by the host body, but at the temperature of the soil at a depth of burrow. The temperature threshold for preimaginal development of conformis fleas is reported to be 10-12 degrees. Temperature below the threshold is fatal for all immature instars. On the contrary the imago can survive at freezing temperature. The annual cycle of the conformis fleas is characterized by the presence of adults throughout the year. They breed in the warmer season and overwinter in the state of reproductive diapause. In this state the fleas are able to attack the host and to feed but do not deposit eggs. In the north deserts the reproduction begins at the early April and terminates at the early September. Southern, the reproductive period is longer. Furthermore, the complete interruption of the reproduction in the autumn-winter time may be absent as it was observed in X. gerbilli gerbilli and X. hirtipes in the south of the Middle Asia. On the other hand it is noted that in southern deserts the rate of oviposition falls in the most hot time. The number of generation per year in the conformis fleas varies from 2-3 in north deserts to 6-7 in south ones. The flea populations peak in late autumn when the insects cease to bread. The high abundance is maintained until springtime. After the diapause is ceased and the fleas begin breeding their abundance declines. In the late spring and early summer the emergence of adults begins and the populations increase. In a mild of summer the second fall takes place and then the fall is replaced by the autumnal peak. On their main hosts the conformis fleas prevail over all other species of Siphonaptera especially for warmer time when their quota among other fleas does not descend as a rule below 90% but more oftently it approaches to 100%. The fleas of this group and especially species parasitizing Rhombomys opimus are remarkable for the high level of their abundance. In the northern deserts in the periods of the most high abundance (late autumn, winter and early spring) the number of fleas per burrow occupied by family of Rh. opimus exceeds usually 1000 specimens and sometimes it can reach several thousands. In the southern deserts the abundance of the fleas is lower but the period of their active parasitizing is longer. In the species parasitizing Rh. opimus it is shown that in a complex burrow only some part of fleas has the possibility to feed regularly. In the spring and summer the percentage of fleas daily attacking the host varied from 17 to 86% and from 10 to 150 ectoparasites feed daily on one animal depending on the quantity of fleas and of hosts in the burrow. The number of attacking fleas is regulated by behaviour of the hosts, which change the used parts of burrow when the fleas are crowded there.     

Use of retinal biopsy to diagnose Bartonella (formerly Rochalimaea) henselae retinitis in an HIV-infected patient

A patient with the acquired immunodeficiency syndrome developed bilateral retinitis due to a Bartonella (formerly Rochalimaea) henselae infection. A retinal biopsy was performed when severe and progressive retinal infection failed to respond to empirical treatment for cytomegalovirus and Toxoplasma gondii. The biopsy specimen was stained with routine histopathological stains and the Steiner silver stain. Ribosomal DNA was extracted from formalinfixed, paraffin-embedded retinal tissue and amplified with the polymerase chain reaction assay, using Bartonella-specific primers. The amplified DNA fragment was cloned and sequenced. Staining with hematoxylin-eosin revealed tufts of proliferating vascular endothelium with numerous fusiformappearing cells, consistent with a diagnosis of bacillary angiomatosis. A Steiner silver stain revealed numerous small bacilli in the biopsy specimen. Amplification of DNA extracted from the tissue produced a fragment of 16S ribosomal DNA of the expected size; sequencing of the DNA fragment revealed that the infection was caused by B henselae. The retinal infection was treated with minocycline, doxycycline, and ciprofloxacin with improvement in visual acuity in the ensuing 12 weeks. To our knowledge, this is the first human immunodeficiency virus-infected patient with retinitis due to B henselae who was diagnosed by the identification of silver-staining bacilli and amplification and sequencing of B henselae with a polymerase chain reaction assay using a biopsy specimen of retinal tissue. Retinal biopsy is indicated, despite its potential for serious complications, in patients with acquired immunodeficiency syndrome who have a progressive, sight-threatening retinitis that is undiagnosed and unresponsive to therapy.     

Experimental infection of domestic sheep with culture-derived Leishmania donovani promastigotes

Domestic sheep were intradermally inoculated with culture-derived stationary phase Leishmania donovani promastigotes. Sampling of site of inoculation, liver and spleen for 244 days showed that this parasite can stay alive in the skin for up to 28 days post-inoculation. Apart from pyrexia that was evident in all the animals for 42 days, no other symptoms of kala-azar were seen. No parasites were recovered from the visceral organs throughout the sampling period, suggesting that sheep are not susceptible to infection with L. donovani. It is therefore unlikely that sheep can be synanthropic reservoirs for this parasite.     

Rapid polymerase chain reaction-based detection of the causative agent of cat scratch disease (Bartonella henselae) in formalin-fixed, paraffin-embedded samples

Bartonella (formerly Rochalimaea) henselae (Bh) plays a central role in cat scratch disease. A polymerase chain reaction (PCR)-based assay that can detect Bh DNA in formalin-fixed, paraffin-embedded (FF-PE) samples would have utility in the evaluation of processed lymph nodes suggestive of this disorder. Fresh or FF-PE cultures of Bh and related species were analyzed. Thirteen lymph nodes (12 FF-PE and one fresh cell suspension) with necrotizing suppurative granulomatous inflammation and seven FF-PE negative control lymph nodes were also evaluated. PCR was performed using a novel, hemi-nested protocol. Amplified products were analyzed by gel electrophoresis. The fresh and FF-PE Bh cultures showed a specific PCR product with an analytical sensitivity of 0.5 pg bacterial DNA. Seven (54%) of 13 clinical lymph node samples with morphological features suggestive of cat scratch disease also had detectable Bh DNA, whereas none of the seven negative control lymph nodes yielded positive results. We have designed a rapid and sensitive PCR test that can reliably detect Bh DNA in fresh and FF-PE samples. Our findings indicate that this assay has clinical utility in the diagnosis of cat scratch disease.     

Experimental infection of Culex (Culex) quinquefasciatus and Aedes (Stegomyia) aegypti with Wuchereria bancrofti

Dioctadecylamidoglycylspermine (DOGS, Transfectam) is a cationic lipid able to interact with DNA to form complexes that mediate efficient gene transfer into various eukaryotic cells. The state of condensation of the plasmid changes with the medium composition. We therefore investigated to what extent the DNA condensation buffer influences the transfection efficiency of Transfectam/DNA particles. Our results show that in a variety of cell lines, a greater than 100-fold difference in luciferase gene expression is observed with Transfectam/DNA complexes at a +/- charge ratio of 0.75 depending on the conditions of complex formation. The best transfection conditions consisted of particles formed in RPMI medium, NaHCO3/Na2HPO4 or sodium citrate solutions. Mixing in a 150 mM sodium chloride solution (as recommended) resulted in lower gene expression. When the helper lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) was present in the DNA/cationic lipid formulation, the increase in reporter activity was also observed, although to a lower extent. Thus, choosing the optimal conditions for formulating DNA/lipid complexes considerably reduces the amount of lipid and DNA needed to obtain maximum gene transfer.     

Experimental alimentary infection of anole lizards (Anolis carolinensis) with Mycobacterium ulcerans

Pathogenic Mycobacterium ulcerans were recovered from the stool of anole lizards up to 11 days after inoculation by stomach tube. M. ulcerans was isolated from the liver of 3 of 20 lizards and acid fast bacteria were seen in the mucosa of intrahepatic bile ducts in 2 of these 10 weeks post-inoculation. These results provide equivocal support for our hypothesis that herpetofauna are a reservoir of infection with M. ulcerans.     

Seroprevalence of antibodies to Bartonella henselae in patients with cat scratch disease and in healthy controls: evaluation and comparison of two commercial serological tests

As the National Library of Medicine expands access to its products and services by making them available on the Internet, more accurate information about current and future access in medical libraries is needed. The National Network Office of the National Library of Medicine conducted a survey of all network member libraries to determine the extent of connectivity and the barriers preventing 100% connectivity. Respondents called a toll-free number and, using interactive voice technology, answered questions concerning Internet access in their library. Seventy-eight percent of the network member libraries responded. Four percent of academic libraries, 27% of hospital libraries, and 10% of "other" libraries reported that they were not connected. Computer cost, lack of in-house expertise, and lack of management support were the highest ranked barriers to connecting. The National Library of Medicine and the Regional Medical Libraries will use information from this survey to develop strategies to help all member libraries achieve full connectivity.     

Experimental infection of axenic mice by "Yersinia enterocolitica" (author's transl)

Although most of Yersinia enterocolitica strains isolated from man have no pathogenicity for laboratory animals, it has been demonstrated that some strains are pathogenic for conventional mice and that most of the strains are probably pathogenic for Nude mice. The authors report the results of the infection of germ-free mice with a strain of Y. enterocolitica which is non pathogenic for holoxenic mice. It appears that C3H/He mice are sensitive to the infection by gavage or aerogenic and peritoneal routes. They all die within 8 to 12 days after injection of an inoculum of 5.10(5) viable cells. Germ-free NCS mice were also sensitive to the oral and aerogenic infection but not to the peritoneal infection; the difference between C3H/He and NCS sensitivity to this way of infection could be explained by a higher bactericidal activity of the peritoneal phagocytes of the latter. The C3H/He and NCS holoxenic control mice infected with the same inoculum of the same strain, did not show any symptoms and all attempts to isolate Y. enterocolitica failed three months after the challenge. Germ-free mice killed by the infection showed histopathological findings, i.e. abscesses involving intestinal wall. liver and spleen; they were similar to those described in experiments with pathogenic strains for conventional mice (holoxenic) and to those observed in infection of athymic Nude mice with strains non pathogenic for conventional mice. This infectious disease model is discussed in regards to the natural human infection.     

Detection of Bartonella henselae by polymerase chain reaction in brain tissue of an immunocompromised patient with multiple enhancing lesions. Case report and review of the literature

PURPOSE: The arteriovenous fistula (AVF) of Brescia-Cimino fulfills nearly all of the criteria for an optimal access for chronic hemodialysis, such as long-term patency rate, low complication rate, and respect of vascular morphologic features. Alternative dialytic methods (i.e., external shunts and vascular grafts) cannot easily be applied to pediatric patients, and in addition, these methods are responsible for higher complication rates. METHODS: From January 1985 to December 1994, 112 Brescia-Cimino AVFs were performed in 90 children (average age, 5.5 years; range, 5 months to 18 years). The average weight of the children was 28 kg (range, 6.5 to 54 kg); 16% of AVFs were performed in children who were less than 5 years old, and 18% in children who were less than 15 kg in body weight. RESULTS: Chronic renal failure was caused by a nephropathy in 53 cases (14 with a nephrotic syndrome), and 37 cases had a uropathy. In all cases a phlebography was performed before the microsurgical treatment. Since 1994 an inflatable tourniquet has been placed on the selected upper arm because of an optimal exsanguination of the operating field. The primary patency rate was obtained in all but six of the children; 35% of AVFs had either immediate or late complications. Thrombosis was the most frequent complication that we observed. In comparison with 79% of late thrombosis, 60% of early thrombosis was cured. Of the 80 AVFs, 63.5% with a 4-year follow-up are still patent. CONCLUSION: We emphasize the following two conclusions: first, microsurgery is essential to create AVFs with good results in children as well as in adult patients; and second, the results improved after the adoption of an upper-arm exsanguination and ischemia (pressure range, 400 mm Hg to 600 mm Hg) that avoided spasm of the vessels with a final 35% reduction in surgical time.     

Flexible search behavior in domestic cats (Felis catus): A case study of predator–prey interaction.

Domestic cats (Felis catus) were administered an object permanence task in a novel and a familiar situation to investigate flexibility (i.e., pause behavior and searching by following a path opposite of that taken by the object when it disappeared) in search behavior. Pause and opposite search were assumed to be independent, equiprobable, and randomly exhibited (i.e., random model). The random model predicted that cats would exhibit flexible behavior on 75% of the trials. The results revealed that flexible behavior occurred on 69% of the trials in the novel situation, but only on 52% of the trials in the familiar setting in which pauses were less frequent and shorter than in the novel situation. Thus, the random model provided a good fit of the data in the novel but not in the familiar situation. It is argued that pause and opposite search reflect decision processes when cats are dealing with the behavior of prey that has disappeared while being pursued. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental infection of maternally immune pigs with porcine reproductive and respiratory syndrome (PRRS) virus

To investigate the influence of maternal antibody to porcine reproductive and respiratory syndrome (PRRS) virus infection, the following examination was done using conventional and SPF pigs. Ten 17-day-old conventional pigs with maternal antibody against PRRS virus and 6 44-day-old SPF pigs seronegative were inoculated intranasally with 10(5.0) TCID50 of PRRS virus. Two conventional and 4 SPF pigs were served as non-inoculated control. In conventional pigs, coughing and febrile response were observed after inoculation, and mean rate of weight gain reduced. One of the inoculated conventional pigs died on post-inoculation-day (PID) 28 and Haemophilus parasuis was isolated from the lung. Although febrile response was also observed in the inoculated SPF pigs, reduction in weight gain rate was not recognized. Virus was isolated from all the sera of inoculated conventional and SPF pigs except one conventional pig between PID 7 and 49, and between PID 7 and 28, respectively. Onset of viremia in the several conventional pigs delayed. Virus was isolated from the tissues of the 5 conventional pigs on PID 65 and from the tissues of the dead pig. On the other hand, virus was not isolated from the tissues of non-inoculated conventional pigs, and inoculated and non-inoculated SPF pigs. At the virus inoculation, antibodies by the indirect fluorescent antibody (IFA) assay against PRRS virus were detected in the sera of conventional pigs with antibody titers of 1:20. Antibody titers gradually decreased after inoculation and rose from PID 21 or 28 and were between 1:160 and 1:640 on PID 63. Virus neutralization (VN) antibody titers were 1:2 or 1:4 at the inoculation and gradually decreased. Apparent rise in VN antibody titer was not observed after the inoculation. In the sera of control pigs, both antibody titers gradually decreased and did not rise. In the sera of the SPF pigs, antibodies by the IFA assay were first detected on PID 7 or 14. The titers of antibodies rose and reached their maximum with 1:320 to 1:2,560 on PID 21 to 35. VN antibodies were first detected in PID 42 to 56 and thereafter, the titers ranged between 1:1 to 1:4. Control SPF pigs were free of antibody throughout the examination. Antigenic variability was not recognized between the inoculated and recovered viruses by the VN test. The prolonged duration of viremia and virus isolation from the tissues on PID 65 in conventional pigs with low maternal antibody might support the present of antibody-dependent enhancement activity of PRRS virus infection.     

At-risk individuals in Feline Immunodeficiency Virus epidemiology: evidence from a multivariate approach in a natural population of domestic cats (Felis catus)

Prevalence of Feline Immunodeficiency Virus (FIV) infection was measured during 6 consecutive years in a natural rural population of domestic cats. Sex, age, weight, origin, group size and presence of antibodies to FIV were recorded for each sampled cat. Logistic regressions were used to estimate the influence of the recorded parameters on infection. FIV prevalence rates are as high as 19.6% in the total population, and do not statistically change between years, after controlling for changes in samples' age structure. FIV infection is characterized by risk factors linked to aggressive behaviour: old mature male adults having dispersed are more likely to be infected. A study of the cats group size and of the spatial distribution of infected individuals indicates the absence of infection clusters in males, and suggests the importance of roaming in the spreading of FIV. In conclusion, FIV infection spreads, with low contagiousness, mainly between particularly aggressive individuals, and the virus is endemic in this population.     

Experimental transmission of Ehrlichia canis (Rickettsiales: Ehrlichieae) by Dermacentor variabilis (Acari: Ixodidae)

Four trials were conducted in which laboratory-reared Dermacentor variabilis nymphs were exposed to Ehrlichia canis by feeding on experimentally infected dogs as soon as classical morulae were detected in peripheral blood monocytes. After molting 25, 50 or 90 adult tick pairs were permitted to feed on 7 Ehrlichia-naive dogs. Transmission occurred in trials 1 (1/1 dog), 3 (1/1 dog) and 4 (2/2 dogs) but not in trial 2 (0/3 dogs), with 4 of 7 dogs becoming infected. Successful transstadial transmission was demonstrated by detection of morulae in peripheral blood lymphocytes and by seroconversion to Ehrlichia canis 30 d post-exposure. Incubation periods ranged between 17 and 22 days (mean = 19). Clinical signs, typical of ehrlichiosis, included mucopurulent ocular discharge, lymphadenopathy and malaise with accompanying pyrexia, leukopenia and thrombocytopenia. Pyrexia, thrombocytopenia and erythrophagocytosis and vacuolization of the cytoplasm of monocytic cells were observed 1-4 d prior to detection of morulae. This is the first demonstration that a tick other than Rhipicephalus sanguineus is capable of transstadial transmission of this important pathogen of dogs.     

Immunization against East Coast fever (Theileria parva infection of cattle) by infection and treatment: chemoprophylaxis with N-pyrrolidinomethyl tetracycline

Cattle were immunized against East Coast fever by the inoculation of a tick-derived stabilate of Theileria parva infective particles and the intramuscular injection, at daily intervals, of n-pyrrolidinomethyl tetracycline at a dose level of 5 mg/kg. Four doses of the tetracycline, starting on the day of inoculation of the infective stabilate, minimised the ECF reactions in the cattle during immunization. Immunity to homologous T. parva stabilate challenge was demonstrated in 27 out of 27 cattle infected and treated in this manner.