PARASITES AND PARASITOSIS IN FISH CULTURE IN PORTUGAL

This paper deals with research work covering the period from May 1979 up to May 1981 and presents results of parasites and parasitosis diagnosed in a total of 195 complete dissections of six fish species from cultured and feral populations in Portugal: European eel (Anguilla anguilla) (49); mirror carp (Cyprinus carpio specularis) (29); common grey mullet (Mugil cephalus) (18); European plaice (Pleuronectes platessa) (11); rainbow trout (Salmo gairdneri) (42); common sole (Solea solea) (46). A list of protozoans and helminths identified with respective incidence is given: A) Feral fish: 1) European eel (17)—Echinorhynchus clavula 11.8% and Rhabdochona anguilla 5.9%; 2) common grey mullet (18)—Haploporus benedenii 16.7%, Neoechinorhynchus sp. 5.6%, and Raphidascaris sp. 5.6%; 3) European plaice (11)—Bothriocephalus sp. larvae 9.1%, Contracaecum aduncum 9.1%, and Cryptocotyle lingua 9.1%; 4) common sole (46)—Cucullanellus minutus 8.7%, Gyrodactylus elegans 4.3%, and Cestodes larvae 2.2%. B) Cultured fish: 1) European eel (32)—Trichodina anguillae 3.1% and Ichthyophthirius multifiliis 18.8%; 2) rainbow trout (42)—Eimeria truttae 2.4%, Hexamita intestinalis 4.8%, Holophrya simplex 2.4%, and Trichodina truttae 4.8%. The results show that feral fish harbor predominantly indirect life cycle helminths, in contrast with cultured fish only affected with protozoans, due mainly to overcrowding and deficient management, which propitiate a significant background infection. It was in these specimens that some lesions characteristic of protozoosis were found.     

Leukocyte-hepatocyte interaction in calicivirus infection: differences between rabbits that are resistant or susceptible to rabbit haemorrhagic disease (RHD)

Calicivirus infection is lethal for adult rabbits, whereas young rabbits (less than 8-weeks-old) are resistant to the same infectious agent. The virus replicates in the liver and causes a fulminant hepatitis in adult rabbits leading to rabbit haemorrhagic disease (RHD); this is in contrast with the mild and transient hepatitis observed in infected young rabbits. We have used electron microscopy to compare liver leukocyte infiltrates between young (resistant) and adult (susceptible) rabbits, 36-48 h after inoculation of the animals with caliciviruses. In adult rabbits, liver infiltrates were made up mostly of heterophils, and they were located near hepatocytes showing severe cellular damage. In contrast, liver leukocyte infiltrates of RHD-resistant young rabbits were dominated by lymphocytes that depicted membrane contacts with the cell surface of undamaged hepatocytes. We conclude that: (i) the cellular inflammatory response of the liver to calicivirus infection is different in rabbits that are susceptible (adult) or resistant (young) to RHD; (ii) leukocyte infiltration of the adult liver by heterophils is probably directed at the removal of dead hepatocytes, whereas the liver lymphocytic infiltration of young rabbits suggests the expression of viral antigens on the surface of liver cells of the RHD-resistant animals.     

Higher incidence of Malassezia pachydermatis in the eyes of dogs with corneal ulcer than in healthy dogs

Malassezia pachydermatis is usually associated with otitis and dermatitis in dogs but it can also cause diseases in other species, including humans. In a human neonatal intensive care unit, M. pachydermatis was isolated from an infant's ocular discharge. Therefore, the aim of this study was to ascertain the presence of Malassezia spp. and its possible consequences in dogs' eyes. This research included 19 dogs with unilateral or bilateral corneal ulcers and 60 healthy dogs. A total of 158 clinical specimens from both the groups were obtained from the conjunctival sac of each eye by a calibrated platinum loop. The samples were placed on Dixon and blood agar, incubated at 35 degrees C, and examined daily for 15 days. Then, the strains were subcultured on Sabouraud agar. Of 22 clinical specimens collected from the eyes with corneal ulcers, five cultures (23%) were positive for M. pachydermatis. Of 16 samples collected from the contralateral healthy eye, cultures were positive in three samples (19%). Three animals had unilateral corneal ulcer and positive cultures for M. pachydermatis in both the eyes. Two dogs had unilateral corneal ulcer and positive cultures for M. pachydermatis in the same eye. However, from the 120 samples of 60 healthy dogs, only four clinical specimens (3%) had positive cultures for M. pachydermatis. The findings of M. pachydermatis, in a considerable percentage of clinical specimens from dogs with corneal ulcer, suggest its possible role at least as an aggravating factor in the pathophysiology of this disease.     

Implications and challenges of tuberculosis in wildlife ungulates in Portugal: a molecular epidemiology perspective

Mycobacterium bovis and, more rarely, Mycobacterium caprae, may cause zoonotic bovine tuberculosis (bTB) in an extensive range of animal species. In Portugal, during 2009, a remarkable raise of bTB incidence was registered in cattle along with an increase of new cases in wildlife. In this work, we reassess and update the molecular epidemiology of bTB in wild ungulates by including 83 new M. bovis and M. caprae isolates from wild boar and red deer obtained during 2008-2009. Spoligotyping identified 27 patterns in wild ungulates, including 11 patterns exclusive from deer and five from wild boar. The genetic relatedness of wildlife and livestock isolates is confirmed. However, the relative prevalence of the predominant genotypes is different between the two groups. Contrasting with the disease in livestock, which is widespread in the territory, the isolation of bTB in wildlife is, apparently, geographically localized and genotypic similarities of strains are observed at the Iberian level.     

Adenosine deaminase activity in serum, erythrocytes and lymphocytes of rats infected with Leptospira icterohaemorrhagiae

Leptospirosis is a systemic disease of humans and domestic animals, mainly dogs, cattle and swine. The course of human leptospirosis varies from mild to severe fatal forms and the most severe form of human leptospirosis is principally caused by Leptospira interrogans serovar icterohaemorrhagiae (L. icterohaemorrhagiae). The enzyme adenosine deaminase (ADA) plays an important role in the production and differentiation of blood cells. The aim of this study was to evaluate the activity of ADA in serum, erythrocytes and lymphocytes of rats infected with L. icterohaemorrhagiae, as compared with non-infected rats. Twenty-four adult rats, divided into two uniform groups (A and B) were used for the enzymatic assays. The animals in Group B were inoculated intraperitoneally with 2×10(8) leptospires/rat, and the rodents in Group A (control) were not-inoculated. Blood collection was performed on days 5 and 15 post-infection (PI) and the blood used to assess the ADA activity. The infection by L.icterohaemorrhagiae altered erythrocyte count, hemoglobin concentration and hematocrit, causing a decrease in all these parameters on day 15 PI. Lymphocytes decreased significantly on day 15 PI, and ADA activity in serum was inhibited in infected rats on days 5 and 15 PI and its activity in erythrocytes were increased on day 5 PI. On day 5 PI, we found an increase in ADA activity in erythrocytes of infected rats. No correlation was observed between hematocrit and erythrocyte ADA activity on days 5 and 15 PI. The ADA activity was inhibited in rats infected on day 15 PI. A positive correlation (r(2)=60) was also observed between the number of lymphocytes and ADA activity in lymphocytes on day 15 PI (P<0.05). In conclusion, our results showed that the ADA activity is altered in serum, lymphocytes and erythrocytes in experimental infection by L.icterohaemorrhagiae in rats, concomitantly with hematological parameters.     

Evaluation of Nociception,Sedation, and Cardiorespiratory Effects of a Constant Rate Infusion of Xylazine Alone or in Combination with Lidocaine in Horses

This study aimed to evaluate the effects of a constant rate infusion (CRI) of xylazine or xylazine in combination with lidocaine on nociception, sedation, and physiologic values in horses. Six horses were given intravenous (IV) administration of a loading dose (LD) of 0.55 mg/kg of xylazine followed by a CRI of 1.1 mg/kg/hr. The horses were randomly assigned to receive three treatments, on different occasions, administered 10 minutes after initiation of the xylazine CRI, as follows: control, physiologic saline; lidocaine low CRI (LLCRI), lidocaine (LD: 1.3 mg/kg, CRI: 0.025 mg/kg/min); and lidocaine high CRI (LHCRI), lidocaine (LD: 1.3 mg/kg, CRI: 0.05 mg/kg/min). A blinded observer assessed objective and subjective data for 50 minutes during the CRIs. In all treatments, heart and respiratory rates decreased, end-tidal carbon dioxide concentration increased, and moderate to intense sedation was observed, but no significant treatment effect was detected in these variables. Ataxia was significantly higher in LHCRI than in the control treatment at 20 minutes of infusion. Compared with baseline values, nociceptive threshold increased to as much as 79% in the control, 190% in LLCRI, and 158% in LHCRI. Nociceptive threshold was significantly higher in LLCRI (at 10 and 50 minutes) and in LHCRI (at 30 minutes) than in the control treatment. The combination of CRIs of lidocaine with xylazine produced greater increases in nociceptive threshold compared with xylazine alone. The effects of xylazine on sedation and cardiorespiratory variables were not enhanced by the coadministration of lidocaine. The potential to increase ataxia may contraindicate the clinical use of LHCRI, in combination with xylazine, in standing horses.     

Minimum infusion rate and hemodynamic effects of propofol, propofol-lidocaine and propofol-lidocaine-ketamine in dogs

ObjectiveTo evaluate the effects of a constant rate infusion (CRI) of lidocaine alone or in combination with ketamine on the minimum infusion rate (MIR) of propofol in dogs and to compare the hemodynamic effects produced by propofol, propofol-lidocaine or propofol-lidocaine-ketamine anesthesia.Study designProspective, randomized cross-over experimental design.AnimalsFourteen adult mixed-breed dogs weighing 15.8 ± 3.5 kg.MethodsEight dogs were anesthetized on different occasions to determine the MIR of propofol alone and propofol in combination with lidocaine (loading dose [LD] 1.5 mg kg^?1, CRI 0.25 mg kg^?1 minute^?1) or lidocaine (LD 1.5 mg kg^?1, CRI 0.25 mg kg^?1 minute^?1) and ketamine (LD 1 mg kg^?1, CRI 0.1 mg kg^?1 minute^?1). In six other dogs, the hemodynamic effects and bispectral index (BIS) were investigated. Each animal received each treatment (propofol, propofol-lidocaine or propofol-lidocaine-ketamine) on the basis of the MIR of propofol determined in the first set of experiments.ResultsMean ± SD MIR of propofol was 0.51 ± 0.08 mg kg^?1 minute^?1. Lidocaine-ketamine significantly decreased the MIR of propofol to 0.31 ± 0.07 mg kg^?1 minute^?1 (37 ± 18% reduction), although lidocaine alone did not (0.42 ± 0.08 mg kg^?1 minute^?1, 18 ± 7% reduction). Hemodynamic effects were similar in all treatments. Compared with the conscious state, in all treatments, heart rate, cardiac index, mean arterial blood pressure, stroke index and oxygen delivery index decreased significantly, whereas systemic vascular resistance index increased. Stroke index was lower in dogs treated with propofol-lidocaine-ketamine at 30 minutes compared with propofol alone. The BIS was lower during anesthesia with propofol-lidocaine-ketamine compared to propofol alone.Conclusions and clinical relevanceLidocaine-ketamine, but not lidocaine alone, reduced the MIR of propofol in dogs. Neither lidocaine nor lidocaine in combination with ketamine attenuated cardiovascular depression produced by a continuous rate infusion of propofol.     

Increased Inflammatory Mediators in Horses Naturally Infected with Trypanosoma vivax. A Preliminary Study

The aim of this study was to measure the levels of inflammatory mediators in serum from horses naturally infected with Trypanosoma vivax. Banked serum samples collected during a previously reported T. vivax natural infection were used to analyze proinflammatory cytokines such as interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin 1 (IL-1), interleukin 6 (IL-6), and nitrite/nitrate (NO_x) levels. We evaluated 12 serum samples from horses from a farm in southern Brazil, four of which had parasitological and molecular diagnoses for T. vivax and presented with clinical signs of disease. Cytokines were assessed by quantitative sandwich enzyme-linked immunosorbent assay, and NO_x was measured using the modified Griess method. Levels of IFN-γ, TNF-α, IL-1, IL-6, and NO_x were increased in serum of infected animals compared to that in noninfected animals. Therefore, infection with T. vivax caused an increase in proinflammatory cytokines and nitric oxide content.