Spatial modelling for low pathogenicity avian influenza virus at the interface of wild birds and backyard poultry.

Low pathogenicity avian influenza virus (LPAIV) is endemic in wild birds and poultry in Argentina, and active surveillance has been in place to prevent any eventual virus mutation into a highly pathogenic avian influenza virus (HPAIV), which is exotic in this country. Risk mapping can contribute effectively to disease surveillance and control systems, but it has proven a very challenging task in the absence of disease data. We used a combination of expert opinion elicitation, multicriteria decision analysis (MCDA) and ecological niche modelling (ENM) to identify the most suitable areas for the occurrence of LPAIV at the interface between backyard domestic poultry and wild birds in Argentina. This was achieved by calculating a spatially explicit risk index. As evidenced by the validation and sensitivity analyses, our model was successful in identifying high-risk areas for LPAIV occurrence. Also, we show that the risk for virus occurrence is significantly higher in areas closer to commercial poultry farms. Although the active surveillance systems have been successful in detecting LPAIV-positive backyard farms and wild birds in Argentina, our predictions suggest that surveillance efforts in those compartments could be improved by including high-risk areas identified by our model. Our research provides a tool to guide surveillance activities in the future, and presents a mixed methodological approach which could be implemented in areas where the disease is exotic or rare and a knowledge-driven modelling method is necessary.

Carriage of Clostridium perfringens by benthic crabs in a sewage-polluted estuary.

The Estuary of Bahía Blanca (EBB), Argentina, is an important wetland under intense sewage pollution. We investigated the occurrence of Clostridium perfringens (CP) in populations of two benthic crabs (Neohelice granulata and Cyrtograpsus angulatus) and in sediment from the EBB. CP was found in 49.1% of the crabs and all of the isolates were identified as type A. The alpha (cpa) and enterotoxin (cpe) encoding genes were identified. Genetic analyses identified 13 novel sequence types, and found no clustering among isolates, suggesting that CP is not part of the crabs' commensal flora. CP carriage was 51 times more likely in crabs from the area nearest sewage outfalls compared with crabs from a reference site. Our in vitro experiments suggest that the carriage of CP in crabs is transient. The use of these benthic crabs as monitoring organisms of sewage pollution in coastal habitats is proposed.

Spatial distribution of canine zoonotic enteroparasites in Bahía Blanca, Argentina / Distribución espacial de enteroparásitos zoonóticos de caninos en Bahía Blanca, Argentina

The objectives of this research were: (1) to determine the occurrence of zoonotic enteroparasites in dog feces from Bahía Blanca, Argentina; (2) to characterize the spatial distribution of the parasites found in association with the quality of life index (QLI) in neighborhoods of Bahía Blanca; and (3) to determine if the presence of a particular parasite genus in a stool sample was facilitated or impeded by the presence of other parasite genera. Samples of dog stools (n = 475) were collected between December 2012 and December 2013 in areas with varying QLI. The association between QLI values and the presence of parasites was analyzed using logistic regression. Overall enteroparasite occurrence was 36.6%. Parasitic forms found included nematode larvae, cysts of Blastocystis spp., Giardia spp., and oocysts of Cryptosporidium spp., and eggs of Ancylostoma caninum, Toxocara canis, cestodes and Trichuris spp. For certain enteroparasites, we detected significant associations between their occurrence and QLI. Feces collected in areas with medium and low QLI were 2.46 and 5.43 times more likely, respectively, to contain A. caninum than stools from the high-QLI area. Samples from areas with low QLI were 2.36 times more likely to contain Trichuris spp. than those from the high QLI area. Regarding protozoa, feces from areas with low QLI were 2.4 times more likely to be positive than those from areas with high QLI. We demonstrated that canine zoonotic parasites have a wide distribution in the study area, and that occurrence is higher in neighborhoods with lower QLI.

Los objetivos del presente trabajo fueron los siguientes: a) determinar la ocurrencia de enteroparásitos zoonóticos en heces de perros de Bahía Blanca, Argentina; b) caracterizar la distribución espacial de los parásitos hallados en función del índice de calidad de vida (ICV) en barrios de Bahía Blanca, y c) determinar si la presencia de un género parasitario en particular en las heces fue facilitada o impedida por la presencia de otro/s. Se recolectaron muestras de heces de perro (n = 475) durante el período diciembre 2012-diciembre 2013 en áreas con diferente ICV. La asociación entre el ICV y la presencia de parásitos fue analizada mediante regresión logística. La ocurrencia global de enteroparásitos fue del 36,6%. Las formas parasitarias detectadas correspondieron a larvas de nematodos, a quistes de Blastocystis spp., Giardia spp. y Cryptosporidium spp., y a huevos de Ancylostoma caninum, Toxocara canis, cestodes y Trichuris spp. Se hallaron asociaciones significativas entre ocurrencia de algunos enteroparásitos e ICV. Las heces recolectadas en áreas con ICV medio y bajo mostraron una probabilidad de contener A. caninum 2,46 y 5,43 veces mayor, respectivamente, que las recolectadas en la zona de ICV alto. Las muestras de zonas con ICV bajo tuvieron una probabilidad 2,36 veces mayor de contener Trichuris spp. que aquellas de áreas con ICV alto. En lo referido a protozoos, las heces de áreas con ICV bajo tuvieron una probabilidad 2,4 veces mayor de presentar quistes que las heces de áreas con ICV alto. Se demostró que los parásitos zoonóticos caninos tienen una amplia distribución en el área estudiada y que la ocurrencia es más alta en los barrios con menor ICV.

Spatial distribution of canine zoonotic enteroparasites in Bahía Blanca, Argentina.

The objectives of this research were: (1) to determine the occurrence of zoonotic enteroparasites in dog feces from Bahía Blanca, Argentina; (2) to characterize the spatial distribution of the parasites found in association with the quality of life index (QLI) in neighborhoods of Bahía Blanca; and (3) to determine if the presence of a particular parasite genus in a stool sample was facilitated or impeded by the presence of other parasite genera. Samples of dog stools (n=475) were collected between December 2012 and December 2013 in areas with varying QLI. The association between QLI values and the presence of parasites was analyzed using logistic regression. Overall enteroparasite occurrence was 36.6%. Parasitic forms found included nematode larvae, cysts of Blastocystis spp., Giardia spp., and oocysts of Cryptosporidium spp., and eggs of Ancylostoma caninum, Toxocara canis, cestodes and Trichuris spp. For certain enteroparasites, we detected significant associations between their occurrence and QLI. Feces collected in areas with medium and low QLI were 2.46 and 5.43 times more likely, respectively, to contain A. caninum than stools from the high-QLI area. Samples from areas with low QLI were 2.36 times more likely to contain Trichuris spp. than those from the high QLI area. Regarding protozoa, feces from areas with low QLI were 2.4 times more likely to be positive than those from areas with high QLI. We demonstrated that canine zoonotic parasites have a wide distribution in the study area, and that occurrence is higher in neighborhoods with lower QLI.

Severe soft tissue ossification in a southern right whale Eubalaena australis.

The carcass of a stranded southern right whale Eubalaena australis, discovered on the coast of Golfo Nuevo in Península Valdés, Argentina, exhibited extensive orthotopic and heterotopic ossification, osteochondroma-like lesions, and early degenerative joint disease. Extensive soft tissue ossification led to ankylosis of the axial skeleton in a pattern that, in many respects, appeared more similar to a disabling human genetic disorder, fibrodysplasia ossificans progressiva (FOP), than to more common skeletal system diseases in cetaceans and other species. This is the first reported case of a FOP-like condition in a marine mammal and raises important questions about conserved mechanisms of orthotopic and heterotopic ossification in this clade.

Enteric infections by trematodes and nematodes in Olrog's gull, Larus atlanticus.

Trematodes and nematodes can be pathogenic helminths of birds. Every year during the breeding season, there is variable mortality among chicks from the largest Olrog's gull (Larus atlanticus) colony in Argentina. During two consecutive breeding seasons of Olrog's gull, we studied epidemiological and pathological aspects of infections by digeneans (Microphallidae) and nematodes (Acuariidae) in Olrog's gull chicks. Prevalence of nematode infection was 80.3% in 2005 and 89.2% in 2006, and mean intensity was 23.7 in 2005 and 50.8 in 2006. The risk for infection rose 34.3% and the intensity of infection 6.7% for every increase of 1 mm in head-beak length. The nematodes occupied the proventricular glands and caused disruption of their structure and mild inflammatory proventriculitis. Prevalence of digenean infection was 97.0% in 2005 and 97.3% in 2006. In 10-day-old live chicks, prevalence was 98.0% in 2006 and 95.3% in 2007. Infection was associated with severe catarrhal enteritis, lymphocyte/eosinophil-rich inflammatory responses, extensive fibroblast proliferation around the parasites, and disruption of the architecture of the adjacent crypts.

Efecto de la temperatura sobre la viabilidad de larvas de Trichinella spiralis / Effect of temperature on the viability of Trichinella spiralis larvae

El objetivo de este estudio fue determinar el efecto de diferentes temperaturas sobre la viabilidad de larvas libres y enquistadas de Trichinella spiralis aisladas en el sudoeste de la provincia de Buenos Aires, Argentina. Se trataron larvas libres y enquistadas a diferentes temperaturas (-30 °C, -20 °C, 4 °C, 20 °C, calentamiento gradual entre 0-100 °C). Se determinó el tiempo necesario para matar el 100 % de las larvas. Durante los primeros días, la mortalidad larvaria en todos los tratamientos con frío aumentó signifcativamente en función del tiempo. En todos los casos, las larvas libres sobrevivieron menor cantidad de días que las enquistadas. A -30 °C, -20 °C y 20 °C no se observaron diferencias signifcativas entre las curvas de mortalidad de cada estadio larvario, pero a 4 °C la mortalidad fue menos intensa entre las larvas enquistadas. El calentamiento disminuyó la viabilidad, sin observarse diferencias entre estadios larvarios. La totalidad de las larvas libres y enquistadas había muerto a los 61 y 95 días (-30 °C), a los 160 y 180 días (-20 °C), a los 280 y 330 días (4° C), y a los 460 y 590 días (20 °C), respectivamente. Fue necesaria una cocción durante 15 minutos a 90 °C para matar al 100 % de las larvas libres y a 100 °C para lograr igual mortalidad de las enquistadas. Nuestros resultados indican que la temperatura y los tiempos tradicionalmente utilizados para tratar productos cárnicos con potencial de transmisión de T. spiralis no serían los más efectivos para lograr la inactivación de la totalidad de larvas vivas de este parásito.

The aim of this work was to study the effect of temperature on the viability of free and encysted larvae of Trichinella spiralis from southwest Buenos Aires province, Argentina. Larvae were treated at variable temperatures (-30 °C, -20 °C, 4 °C, 20 °C, gradual heating between 0-100 °C). The time necessary to kill 100 % of larvae was calculated. During the frst days of freezing, larval mortality signifcantly increased as a function of time. Regardless of temperature, encysted larvae survived longer than the free ones. At -30 °C, -20 °C, and 20 °C there were no signifcant differences between the survival curves for each larval stage. At 4 °C, mortality was less severe for encysted larvae. All free and encysted larvae died at 61 days and 95 days (-30 °C), 160 days and 180 days (-20 °C), 280 days and 330 days (4 °C) and 460 days and 590 days (20 °C), respectively. Cooking at 90 °C and 100 °C during 15 minutes killed 100 % of free and encysted larvae, respectively. Our results suggest that temperatures and exposure times traditionally used to treat meat products with a potential to transmit T. spiralis are not entirely effcient.

[Effect of temperature on the viability of Trichinella spiralis larvae]. / Efecto de la temperatura sobre la viabilidad de larvas de Trichinella spiralis.

The aim of this work was to study the effect of temperature on the viability of free and encysted larvae of Trichinella spiralis from southwest Buenos Aires province, Argentina. Larvae were treated at variable temperatures (-30 °C, -20 °C, 4 °C, 20 °C, gradual heating between 0-100 °C). The time necessary to kill 100 % of larvae was calculated. During the first days of freezing, larval mortality significantly increased as a function of time. Regardless of temperature, encysted larvae survived longer than the free ones. At -30 °C, -20 °C, and 20 °C there were no significant differences between the survival curves for each larval stage. At 4 °C, mortality was less severe for encysted larvae. All free and encysted larvae died at 61 days and 95 days (-30 °C), 160 days and 180 days (-20 °C), 280 days and 330 days (4 °C) and 460 days and 590 days (20 °C), respectively. Cooking at 90 °C and 100 °C during 15 minutes killed 100 % of free and encysted larvae, respectively. Our results suggest that temperatures and exposure times traditionally used to treat meat products with a potential to transmit T. spiralis are not entirely efficient.

Intestinal Acanthocephaladiosis in Olrog's gulls (Larus atlanticus): Profilicollis chasmagnathi as possible cause of death.

In 2003 and 2005, mortality events were observed among hatch-year Olrog's gulls (Larus atlanticus) in a breeding colony in the Bahía Blanca estuary, Argentina. Freshly dead chicks were collected for parasitologic and parasite-associated pathologic studies. Profilicollis chasmagnathi was found at various intensities in all of the birds examined (n=28). On gross and histopathologic examinations, severe lesions ranging from intestinal obstruction to complete perforation were present in small and large intestines of the birds. Larval forms of P. chasmagnathi were being found in prey items of L. atlanticus in the study area, which suggests that diet may play a central role in the epidemiology of disease and mortality events in this species.