Genetic diversity and geographic distribution of parasitic flies of the Philornis torquans complex in Argentina.

Philornis Meinert 1890 (Diptera: Muscidae) is a genus of flies that parasitize birds in the Neotropical region. The characteristics of the host-parasite interactions and its consequences may depend on the Philornis species involved, and thus precise identification of these parasites is crucial for the interpretation of ecological and epidemiological studies. However, morphological identification of Argentine Philornis species is elusive while molecular evidence points towards the existence of a complex of cryptic species or lineages undergoing a speciation process, which were named the 'Philornis torquans complex'. Herein the authors extended the current knowledge on the systematics and biogeography of parasitic Philornis flies from Argentina, analysing samples collected in several ecoregions, including the Atlantic Forest, Iberá Wetlands, Open Fields and Grasslands, Espinal, Pampa, Dry Chaco, Humid Chaco, Delta and Paraná River Islands, Monte of Plains and Plateaus. The results of the present study strengthen the evidence on previously described Philornis genotypes using four genetic markers (ITS2, COI, ND6, 12S rRNA). The authors report new patterns of occurrence and describe the presence of a novel genotype of subcutaneous Philornis. In addition, the present study unveils ecological niche differences among genotypes of the Philornis torquans complex in southern South America.

Environmental variables determining the distribution of an avian parasite: the case of the Philornis torquans complex in South America.

Philornis flies are the major cause of myiasis in nestlings of Neotropical birds, being of major concern in geographically-restricted and endangered bird species. Despite its relevance for the conservation of birds, there is little information about the environmental dimensions determining Philornis spp. geographical range. By using maximum entropy, we identified for the first time the macro-environmental variables constraining the abiotic niche of the P. torquans complex in South America, and provided a model map of its potential distribution based on environmental suitability. We identified the minimum temperature of the coldest month as the most relevant variable, associated with the largest decrease in habitat suitability in Brazil and northern South America. Furthermore, the mean temperature of the warmest quarter limited suitability mostly along with the Andean range. In addition, humidity and moisture are influential factors in most of Argentina, northern Chile, and coastal Peru. The geographical projection suggests that environments in most of central-eastern Argentina, and in a broad area in central Chile, are suitable for the presence of the P. torquans complex. Besides providing information about the ecology of Philornis spp., this study represents a tool for bird conservation and a reference for future work on the distribution of this genus.

The tropical fowl mite, Ornithonyssus bursa (Acari: Macronyssidae): environmental and host factors associated with its occurrence in Argentine passerine communities.

The tropical fowl mite, Ornithonyssus bursa, is a common avian parasite found on diverse bird species worldwide. In the Neotropical region, O. bursa is present in wild birds, but it may also infect poultry and bite humans. Little is known about the ecology and epidemiology of this parasite. We conducted a thorough longitudinal study in passerine assemblages from central Argentina, gathering data from six reproductive seasons, with the aim of identifying factors that have a role in driving the occurrence and distribution of O. bursa in its natural hosts. We focused on the brood and microhabitat levels, accounting for potential confounders of higher levels. The results hereby presented contribute to our knowledge on the eco-epidemiology of O. bursa in natural hosts of the Neotropical region. Among the many variables assessed, nest material and host species appeared to be the most important correlates of O. bursa prevalence. Nonetheless, supplementary analyses showed that host species is a stronger predictor than nest material. Moreover, mite burden (parasite intensity) was found to depend on host species, but not on nest material. The association with species depended on nestling age, suggesting that resistance builds up as the nestling develop, but at a different pace depending on the bird species. Brood size was inversely correlated with intensity of parasitism, suggesting a dilution of the parasite burden on each nestling.

Isolation and molecular characterization of Toxoplasma gondii in a colony of captive black-capped squirrel monkeys (Saimiri boliviensis).

Toxoplasmosis is commonly asymptomatic; however, it can be a fatal multisystemic disease in some animal species, such as New World monkeys. An outbreak of acute fatal toxoplasmosis was reported in a colony of black-capped squirrel monkeys (Saimiri boliviensis) from the zoo of La Plata, Argentina. Post-mortem examination of two monkeys revealed macroscopical and microscopical lesions compatible with acute toxoplasmosis. The presence of Toxoplasma gondii was confirmed by immunohistochemistry on monkey tissues, bioassay in mice and PCR using the specific primers B22-B23. By PCR-RFLP analysis, T. gondii isolated in mice, deriving from both monkeys, showed the same restriction pattern, with most markers showing a type III restriction pattern, except for C22-8 (type II) and C29-2 (type I). To our knowledge this is the first report of fatal toxoplasmosis in S. boliviensis caused by a non-canonical or atypical genotype of T. gondii.

Ileal ganglioneuromatosis in a piglet: histopathological and immunohistochemical studies.

Ganglioneuromatosis (GNM) is a rare condition characterized by the benign proliferation of ganglion cells, nerve fibres and supporting cells of the enteric nervous system. Necropsy examination of a female piglet weighing 4 kg revealed a well-demarcated 20 cm segment of terminal ileum with thickening of the wall. Microscopically, the lamina propria was infiltrated by enteric glial cells and large ganglion cells. Within the submucosal and muscular layers, aggregates of neurons were interlaced by Schwann cells and enteric glial cells arranged in concentric rings. Immunohistochemically, the neurons were weakly labelled for S-100 and neuron-specific enolase, Schwann cells expressed S-100 and vimentin and enteric glial cells expressed glial fibrillary acidic protein and S-100. Pathological and immunohistochemical findings supported the diagnosis of ileal GNM.

Effect of a single dose of cadmium on pregnant Wistar rats and their offspring.

Cadmium (Cd) is a well-known toxicant targeting many organs, among them placenta. This heavy metal also has embryonary and foetal toxicity. This study was undertaken to analyse the effect of a single Cd dose administered at 4, 7, 10 or 15 days of gestation on the offspring of pregnant rats sacrificed at 20 days of gestation. Cadmium chloride was administered subcutaneously at 10 mg/kg body weight to Wistar pregnant dams; control animals received a proportionate volume of sterile normal saline by the same route. Maternal uteri, livers, kidneys and lungs, and foetuses were examined at necropsy. Samples of maternal organs and whole foetuses were collected for histopathologic examination, determination of Cd levels and staining by the Alizarin red S technique. Results revealed a clear embryotoxic and a teratogenic effect of this heavy metal, the former as a significant increase in the number of resorptions, and the latter as significant decrease of the gestational sac weight, and the size and weight of foetuses of Cd-treated dams as well as induced malformations in skull bones, vertebrae and thoracic, and pelvian limbs. The deleterious effects found were similar to those previously reported for other animal models suggesting a high conservation of the pathogenic mechanisms of Cd. Additionally, many of the addressed aspects showed a slight dependence on the time of administration of the toxic that might be due to the accumulation of the metal in different organs, as we were able to demonstrate by the analysis of its concentration.

[Seroprevalence of the swine influenza virus in fattening pigs in Argentina in the 2002 season: evaluation by hemagglutination-inhibition and ELISA tests]. / Prevalencia serológica del virus de influenza A en cerdos en Argentina durante la temporada 2002: evaluación mediante inhibición de la hemaglutinación y ELISA.

The seroprevalence of the Influenza virus against H1N1 and H3N2 was determined by the hemagglutination-inhibition test (HI) and a commercial swine influenza ELISA kit, in 13 Argentinean swine herds. The results of within-herd and between-herd prevalence obtained by both tests were statistically correlated. The within-herd prevalence observed by the HI test varied from 38.46 to 100% against H1 and 7.69 to 100% for H3. When the within-herd prevalence was measured with the ELISA test, it varied from 2.33 to 6.9% for H1 and 9.65 to 48% for H3. No statistical differences were observed at herd level between HI and ELISA (H1: p = 0. 20; H3: p=0.11). No agreement between HI and ELISA detected prevalence was observed when the within-herd prevalence was compared (H1: 0.005; H3: 0.070), while the agreement at herd level was considered poor (H1: 0,350; H3: 0,235). The high within-herd prevalence values observed with the HI test and the high sensibility of this test might show that human strains or swine strains phylogenetically closely related to the humans strains used in the HI test in this study have been affecting the swine population since 2002.

Prevalencia serológica del virus de influenza A en cerdos en Argentina durante la temporada 2002: evaluación mediante inhibición de la hemaglutinación y ELISA / Seroprevalence of the swine Influenza virus in fattening pigs in Argentina in the 2002 season: evaluation by hemagglutination-inhibition and ELISA tests

Se evaluó la prevalencia serológica del virus de influenza mediante las pruebas de inhibición de la hemaglutinación (IHA) y ELISA para los subtipos H1N1 y H3N2 en 13 granjas porcinas de Argentina. Se compararon los resultados obtenidos mediante ambas pruebas en términos individuales y de establecimientos. La prevalencia individual por la técnica de IHA fue de 38,46% a 100% para H1 y de 7,69% a 100% para H3. Por la técnica de ELISA, la prevalencia individual fue de 2,33% a 6,9% para H1 y de 9,65% a 48% para H3. No se observaron diferencias significativas entre ambas técnicas a escala de granja (H1: p=0,20; H3: p=0,11). La concordancia entre las pruebas fue nula al tomar como unidad de referencia el animal (H1: 0,005; H3: 0,070), mientras que en términos de establecimiento fue escasa (H1: 0,350; H3: 0,235). Considerando la alta prevalencia individual obtenida por la prueba de IHA y la alta sensibilidad de esta técnica, se podría sugerir que en las poblaciones porcinas de la Argentina circularon cepas virales humanas o cepas porcinas con gran proximidad filogenética a las utilizadas en este estudio desde el año 2002.

The seroprevalence of the Influenza virus against H1N1 and H3N2 was determined by the hemagglutination-inhibition test (HI) and a commercial swine influenza ELISA kit, in 13 Argentinean swine herds. The results of within-herd and between-herd prevalence obtained by both tests were statistically correlated. The within-herd prevalence observed by the HI test varied from 38.46 to 100% against H1 and 7.69 to 100% for H3. When the within-herd prevalence was measured with the ELISA test, it varied from 2.33 to 6.9% for H1 and 9.65 to 48% for H3. No statistical differences were observed at herd level between HI and ELISA (H1: p = 0. 20; H3: p=0.11). No agreement between HI and ELISA detected prevalence was observed when the within-herd prevalence was compared (H1: 0.005; H3: 0.070), while the agreement at herd level was considered poor (H1: 0,350; H3: 0,235). The high within-herd prevalence values observed with the HI test and the high sensibility of this test might show that human strains or swine strains phylogenetically closely related to the humans strains used in the HI test in this study have been affecting the swine population since 2002.

Isolation and molecular characterization of Toxoplasma gondii from captive slender-tailed meerkats (Suricata suricatta) with fatal toxoplasmosis in Argentina.

In this study, the diagnosis of fatal disseminated toxoplasmosis in three captive slender-tailed meerkats (Suricata suricatta) in the zoo of La Plata, Argentina and the invitro isolation and molecular characterization of Toxoplasma gondii are reported. The animals showed depression, dyspnea and hypothermia, and also ataxia in one case, and died within 1-5 days. The main histopathological lesions included interstitial pneumonia, non-suppurative inflammatory changes and focal necrosis in liver, spleen, kidney and brain. Tachyzoites or tissue cysts were present in lung, liver, spleen, brain, striated muscle, kidney, intestine and mesenteric lymph node sections, and stained strongly with T. gondii antiserum in immunohistochemical analysis. T. gondii was isolated in Swiss mice and in bovine monocytes cultures from tissues of one of the meerkats. The isolate was cryopreserved and it was named TG-Suricata-1. T. gondii DNA was demonstrated in tissues of all three animals and in tachyzoites isolated in cell cultures. The PCR-RFLP analysis of markers based in the loci 3'-SAG2, 5'-SAG2, BTUB, GRA6, SAG3, c22-8, L358, PK1, c29-2 and Apico of T. gondii produced patterns corresponding to the clonal type III. Type III strains of T. gondii possess no or only little virulence in the mouse model, however their association with virulence in other animal species is uncertain. In the present case, T. gondii of the clonal lineage III was responsible for fatal cases in S. suricatta. To our knowledge, this is the first report of isolation and genotyping of T. gondii from S. suricatta.

A simple method of infecting rabbits with Bovine herpesvirus 1 and 5.

This report describes an alternative technique to inoculate rabbits and to reproduce infection by Bovine herpesvirus 1 and 5. First, the nostrils are anaesthetized by aspersion with local anaesthetic. A few seconds later, and after proving the insensitivity of the zone, the rabbits are put on their back legs with their nostrils upwards and the inoculum is introduced slowly into each nostril by using disposable droppers. Clinical signs, viral isolation from nasal swabs, histological lesions found, positive polymerase chain reaction and antibodies production confirm the infection. This very simple and bloodless technique, where the animals are exposed to minor distress, may be useful for evaluating the virulence of BoHV-1 and BoHV-5 strains, to study the establishment of latent virus infection and to test the potential of experimental vaccines or properties of antiviral drugs. It may be also suitable for experimental infection with other respiratory viruses in this animal model.

[Experimental model for the study of molybdenosis in the primary copper deficiency in rats]. / Modelo experimental para el estudio de la molibdenosis y de la deficiencia primaria de cobre en ratas.

An experimental model in rats was evaluated to differentiate the effects between Copper deficiency and Molybdenosis. Sixty weaning rats (30 male and 30 female) received a diet with 70% complete powder milk (1 ppm Cu) and 30% maize meal (0.8-1.5 ppm Cu). Three experimental groups received the following mineral supplementation: copper deficiency (40 ppm Fe), molybdenosis (40 ppm Fe + 40 ppm Cu + 500 ppm Mo) and control (40 ppm Fe + 40 ppm Cu). The animals were weighed each 14 days. At 70 days of treatment were sacrificed. Blood and liver were sampled for analyzing hematocrit, ceruloplasmin activity and Cu and Mo liver concentration. Copper deficiency group had less serum ceruloplasmin activity. Cu and Mo liver concentration were higher in the animals with molybdenosis. We concluded that when Cu levels are higher than minimum requirement, feeding with high Mo, do not affect ceruloplasmin activity. In addition, high Mo liver concentration allows us to elucidate effects "per se" of molybdenosis.

Modelo experimental para el estudio de la molibdenosis y de la deficiencia primaria de cobre en ratas / Experimental model for the study of molybdenosis in the primary copper deficiency in rats

Con el objetivo de diferenciar los efectos producidos por la deficiencia primaria cobre y los provocados por el excesso de molibdeno se evaluó un modelo experimental en ratas. Sesenta ratas de destete (30 machos y 30 hembras) recibieron una dieta compuesta por 70 por ciento de leche entera en polvo (1 ppm Cu) y 30 por ciento de harina de maíz (0.8 - 1.5 ppm Cu). Los animales se dividieron en tres grupos conforme a la suplementación mineral recibida: deficiencia primaria de cobre (40 ppm Fe), molibdenosis (40 ppm Fe + 40 ppm Cu + 500 ppm Mo) y controles (40 ppm Fe + 40 ppm Cu). Se pesaron cada 14 días. Al cabo de 70 días de tratamiento se obtuvieron muestras de sangre para determinación de hematocrito y actividad sérica de ceruloplasmina y se sacrificaron para medir concentraciones hepáticas de Cu y Mo. El grupo deficiente en Cu tuvo valores significativamente inferiores en la actividad de ceruloplasmina. Las concentraciones hepáticas de Cu y Mo fueron superiores significativamente en los animales con molibdenosis. Se concluye que con niveles de Cu por encima de los requerimientos mínimos, la alimentación con alto contenido de Mo, no afecta la actividad sérica de ceruloplasmina. Esto sumado a la concentración hepática de Mo lograda, permitirá identificar efectos "per se" de la molibdenosis.

Modelo experimental para el estudio de la molibdenosis y de la deficiencia primaria de cobre en ratas. / [Experimental model for the study of molybdenosis in the primary copper deficiency in rats]

An experimental model in rats was evaluated to differentiate the effects between Copper deficiency and Molybdenosis. Sixty weaning rats (30 male and 30 female) received a diet with 70

complete powder milk (1 ppm Cu) and 30

maize meal (0.8-1.5 ppm Cu). Three experimental groups received the following mineral supplementation: copper deficiency (40 ppm Fe), molybdenosis (40 ppm Fe + 40 ppm Cu + 500 ppm Mo) and control (40 ppm Fe + 40 ppm Cu). The animals were weighed each 14 days. At 70 days of treatment were sacrificed. Blood and liver were sampled for analyzing hematocrit, ceruloplasmin activity and Cu and Mo liver concentration. Copper deficiency group had less serum ceruloplasmin activity. Cu and Mo liver concentration were higher in the animals with molybdenosis. We concluded that when Cu levels are higher than minimum requirement, feeding with high Mo, do not affect ceruloplasmin activity. In addition, high Mo liver concentration allows us to elucidate effects [quot ]per se[quot ] of molybdenosis.

Modelo experimental para el estudio de la molibdenosis y de la deficiencia primaria de cobre en ratas / Experimental model for the study of molybdenosis in the primary copper deficiency in rats

Con el objetivo de diferenciar los efectos producidos por la deficiencia primaria cobre y los provocados por el excesso de molibdeno se evaluó un modelo experimental en ratas. Sesenta ratas de destete (30 machos y 30 hembras) recibieron una dieta compuesta por 70 por ciento de leche entera en polvo (1 ppm Cu) y 30 por ciento de harina de maíz (0.8 - 1.5 ppm Cu). Los animales se dividieron en tres grupos conforme a la suplementación mineral recibida: deficiencia primaria de cobre (40 ppm Fe), molibdenosis (40 ppm Fe + 40 ppm Cu + 500 ppm Mo) y controles (40 ppm Fe + 40 ppm Cu). Se pesaron cada 14 días. Al cabo de 70 días de tratamiento se obtuvieron muestras de sangre para determinación de hematocrito y actividad sérica de ceruloplasmina y se sacrificaron para medir concentraciones hepáticas de Cu y Mo. El grupo deficiente en Cu tuvo valores significativamente inferiores en la actividad de ceruloplasmina. Las concentraciones hepáticas de Cu y Mo fueron superiores significativamente en los animales con molibdenosis. Se concluye que con niveles de Cu por encima de los requerimientos mínimos, la alimentación con alto contenido de Mo, no afecta la actividad sérica de ceruloplasmina. Esto sumado a la concentración hepática de Mo lograda, permitirá identificar efectos "per se" de la molibdenosis. (AU)

Mycotoxin T-2 and aflatoxin B1 as immunosuppressors in mice chronically infected with Toxoplasma gondii.

The aim of this study was to determine whether repeated ingestion of mycotoxin T-2 (T2) or aflatoxin B1 (AFL) at low doses could contribute to the activation of toxoplasmosis in experimentally infected mice. Mice were divided into two groups: Control (C) and Infected (I). The cyst-forming Beverley strain of Toxoplasma gondii was used to produce the infection one month before treatment with mycotoxins. Mycotoxins were given intragastrically for a 50-day period. The average weight gain was reduced in the groups treated with mycotoxins. Mice developed specific IgG to T. gondii. Histopathological studies showed severe encephalitis in all groups infected. The number of unruptured and ruptured cysts was established and the severity of the lesions was evaluated, the groups treated with mycotoxins being the most severely affected. Immunohistochemical studies of the brain showed free antigen in tissues surrounding ruptured cysts. It is suggested that low and repeated doses of mycotoxins, necessary to produce a subclinical intoxication, precipitate Toxoplasma cyst rupture and consequently the activation of chronic toxoplasmosis.

Treatment of recurrent and resistant CAPD peritonitis by temporary withdrawal of peritoneal dialysis without removal of the catheter.

Recurrent and resistant continuous ambulatory peritoneal dialysis (CAPD) peritonitis is usually treated by removal of the catheter and temporary hemodialysis. We treated 3 patients: 1 with resistant Klebsiella peritonitis and 2 with recurrent peritonitis (one due to Staphylococcus and the other to Enterococcus), by stopping CAPD for a 2-4 week period, leaving the catheter in situ and continuing antibiotic therapy. All 3 patients had resolution of their infections and restarted CAPD. This therapeutic modality reduced catheter replacements, limited admissions to the hospital, reduced psychological impact, and diminished risks and costs of CAPD.