Presencia de Pseudosuccinea columella naturalmente infestada con Fasciola hepatica en Santo Tomé (Corrientes, Argentina)

La fasciolosis es una enfermedad producida por Fasciola hepatica. Esta parasitosis produce grandes pérdidas económicas en el ganado bovino de la Provincia de Corrientes, Argentina, y también tiene carácter zoonótico. En el norte de la Provincia, Pseudosuccinea columella es el caracol involucrado en la transmisión de la enfermedad. El objetivo del presente trabajo fue ampliar los datos sobre la distribución de P. columella y su infestación natural por F. hepatica en la Provincia de Corrientes. Se recolectaron caracoles en un establecimiento ganadero del Departamento de Santo Tomé, al nordeste de la Provincia, que fueron identificados taxonómicamente, medidos y disecados para verificar la presencia de cercarias de F. hepatica. Los 115 caracoles recolectados fueron identificados como P. columella. La longitud de la conchilla varió entre 0,8–21,3 mm, con una media de 10,0 mm. La prevalencia de caracoles naturalmente infestados por F. hepatica fue de 8 (7,4%) sobre 108 examinados. La presencia de P. columella en distintos departamentos del norte y nordeste de la Provincia de Corrientes y las altas prevalencias de infestación natural por F. hepatica registradas, indicarían el asentamiento de un ciclo de transmisión enzoótica en esta zona

Comparison of two coprological methods for the veterinary diagnosis of fasciolosis Comparação de dois métodos coprológicos para diagnóstico da fasciolose

The sensitivity and utility of a standard faecal sedimentation method (FSM) and a modified stool sieving staining method (FSSM), both currently employed for the diagnosis of Fasciola hepatica infection were compared. Faecal samples were obtained from 51 bovines of an endemic area for fasciolosis in Southwestern Argentina. Each sample was placed in a recipient containing 5% formalin. Eight millilitres of the suspension, equivalent to 2g of faeces, were used for each of the two methods tested. The number of eggs found per sample was recorded. The proportion of positive samples obtained by the FSSM (27/51) was significantly higher than that by the FSM (11/51) (P<0.05). The percent of agreement between methods was 41%. Over a total of 27 positive samples detected by the FSSM, the FSM missed 16, yielding 60% false negative samples. The FSSM enhanced 2.5 times the sensitivity of diagnosis. The complexity of the FSM may decrease its sensitivity through missing and loss of eggs during sample processing. These results confirmed that the commonly used FSM underestimates the prevalence and the egg output in cattle and that the FSSM is a more reliable diagnostic method.<br>Compararam-se a sensibilidade dos métodos padrão de sedimentação fecal (MPSF) e modificado da tamisação e coloração das fezes (MTCF)-quatro tamises, ambos empregados no diagnóstico de infecção por Fasciola hepatica. Amostras de fezes foram obtidas de 51 bovinos oriundos de uma área endêmica por fasciolose no Sudoeste da Argentina. Cada amostra foi colocada em um recipiente contendo formalina 5%. Oito mililitros da suspensão, equivalente a 2g de fezes, foram usados em cada método testado, registrando-se o número de ovos por amostra. A porcentagem de amostras positivas pelo MTCF (27/51) foi maior que a apresentada pelo MPSF (11/51), o que representou 60% de amostras falso-negativas. A porcentagem de concordância pelos dois métodos foi 41%. A complexidade do MPSF pode diminuir sua sensibilidade pela perda de ovos durante o processamento. Estes resultados confirmaram que o MPSF subestima a contagem de ovos e que o método MTCF é mais confiável

Early and late effects of feed restriction on survival, growth and hepatopancreas structure in juveniles of the red claw crayfish Cherax quadricarinatus

The objective of this study is to estimate the point-of-reserve-saturation 50 (PRS50) of stage III (JIII) and 1-gram (J1g) juveniles of Cherax quadricarinatus and to evaluate the early and late effects of feeding restriction on survival, growth and hepatopancreas structure. The experiments consisted of different feeding treatments followed by continuous starvation until molting to the following stage (restriction period). After molting, juveniles were fed daily until the end of the experiment (refeeding period). The PRS50 estimated for JIII was 2.05±0.11days, according to which 2 feeding days were required for 50% of the JIII to molt to JIV. However, the value of growth increment and the presence of hepatopancreatic abnormalities showed that these molted juveniles were not in optimal conditions. Their hepatopancreas showed a significant recovery during the refeeding period. This suggests that mortality in JIII exposed to a feeding restriction period close to the PRS50 occurs earlier than in the following stages and that the survivors recover after a refeeding period. The PRS50 of JIII could be used to test offspring quality, with the immediate advantage of reducing maintenance costs of poor-quality juveniles. The PRS50 estimated for J1g was 9.19±0.54days; those fed for less than 9days exhibited higher mortality during the restriction period, and those of F8 and F9 had histological abnormalities after the refeeding period. The mortality in J1g of F9 increased at the end of the experiment, suggesting that although they would be able to molt in a proportion similar to the control, they die later as a consequence of the restriction period. In this study, the relative wet hepatopancreas weight (RHW) was similar among treatments and between both experiments even when histological examination showed nutritional stress, implying that the RHW estimated with wet weight is a poor indicator of nutritional status. An adequate management in terms of reducing the amount of food and the use of proper tools for monitoring the health of cultured animals are essential for improving profits. In this context, the values of PRS50 and the information obtained from the present study are useful to establish a feeding schedule for the production of C. quadricarinatus.Fil: Calvo, Natalia Soledad. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Stumpf, Liane. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pietrokovsky, Silvia Monica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Greco, Laura S. López. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentin

Feeding patterns of Triatoma longipennis Usinger (Hemiptera, Reduviidae) in peridomestic habitats of a rural community in Jalisco State, Mexico

We analyzed triatomine blood feeding patterns to evaluate the role of peridomiciles in Trypanosoma cruzi transmission at the rural village of Tepehuaje de Morelos at Jalisco State, Mexico (1999). A total of 206 bugs were collected in 11 out of 26 households (42.3%). Nymphs predominated in the collections (64.9% of the total). Except for one Triatoma barberi female, a species that belongs to the protracta species complex, all adults were Triatoma longipennis, a species of the phyllosoma complex. Triatomines were exclusively present in peridomestic sites mainly piles of tiles and bricks, and none were found indoors. Overall infection rate was 56.6% and no significant differences (P > 0.05) were observed between nymphs and adults or males and females. Identified blood meals were chicken (29.4%), opossum (20.9%), pig (24.5%), murid (20.9%), dog (3.5%), and armadillo (0.7%). No gut content reacted against anti-human, anti-bovine, anti-rabbit, and anti-cat sera. In contrast to fifth nymphs and adults, 87% of the small nymphs fed on one host, indicating that they are less mobile than other stages. Most fifth nymphs and adults fed on domestic hosts, while small nymphs mainly fed on opossum and murid. Infection blood-meal indexes were around 50% for single meals on opossum and murid, stressing their importance as trypanosome donors. Peridomiciles in Tepehuaje could be regarded as interaction sites among domestic and wild and synanthropic mammals and triatomines, which would facilitate circulation of the same T. cruzi strains between domestic and sylvatic cycles. Stone-made walls and building materials, which hold synanthropic rodents and opossums, should be considered as targets for vector control measures