F.A. Rojo-Vázquez

Epidemiological pattern and risk factors associated with bovine viral-diarrhoea virus (BVDV) infection in a non-vaccinated dairy-cattle population from the Asturias region of Spain.

A survey of bovine viral-diarrhoea virus (BVDV) infection was carried out in a non-vaccinated cattle population from the Asturias region of Spain in 1997 to assess seroprevalence and identify risk factors associated with infection. Twenty-eight herds were included; 529 cows were bled. Information regarding the herd and each animal sampled were recorded through a personal interview with the farmer. The true prevalence was estimated to be 21%. According to the antibody-age profiles and the herd-management characteristics, no persistently infected animals were suspected at that time within the herds sampled. Random-effects logistic regression found two major factors associated with seropositivity: age and cow origin. Results suggested that BVDV infection could be controlled in that area by livestock-trade control (without vaccines). In addition, an increasing risk of abortion was not observed when cows were seropositive to both BVDV and Neospora caninum infections.

Update on trematode infections in sheep.

Trematode parasites live in the liver, fore stomachs or blood vessels of a wide range of animals and humans. Most of them have a special economic and veterinary significance. Liver fluke disease of sheep and other animal species is caused by the common liver fluke Fasciola hepatica. Hepatic fasciolosis occurs throughout the world, where climatic conditions are suitable for the survival of aquatic intermediate host snails. Also of importance for ruminants, in some parts of the world, are Fasciola gigantica and Fascioloides magna. Other trematodes infecting ruminants include Dicrocoelium dendriticum; Eurytrema pancreaticum and Eurytrema coelomaticum. Among the Paramphistomidae, some species can infect sheep and other ruminants. Finally, Schistosoma spp. are found in the blood vessels of ruminants and are of minor importance in temperate regions. The manuscript concentrates on trematode species of veterinary importance for domestic sheep.

Cystic echinococcosis in Spain: current situation and relevance for other endemic areas in Europe.

Cystic echinococcosis (CE) remains an important health problem in many regions of the world, both where no control measures have been implemented, and where control programs have been incompletely successful with ensuing re-emergence of the disease. In Spain, official data on CE show an increase in the proportion of intermediate hosts with CE during the last few years, and autochthonous pediatric patients have been reported, a sign of active local transmission of disease. A similar picture emerges from data reported to the European Food Safety Authority by other European countries. Nevertheless, several crucial aspects related to CE that would help better understand and control the disease have not been tackled appropriately, in particular the emergence of infection in specific geographical areas. In this respect, while some data are missing, other data are conflicting because they come from different databases. We review the current situation of CE in Spain compared with areas in which similar problems in the CE field exist, and offer recommendations on how to overcome those limitations. Specifically, we believe that the introduction of national registries for CE with online data entry, following the example set by the European Registry for Alveolar Echinococcosis, would help streamline data collection on CE by eliminating the need for evaluating and integrating data from multiple regions, by avoiding duplication of data from patients who access several different health facilities over time, and by providing much needed clinical and epidemiological data that are currently accessible only to clinicians.

Prevalence study of the lungworm Aelurostrongylus abstrusus in stray cats of Portugal

In this study we have investigated the prevalence of aelurostrongylosis, one of the most common feline pulmonary parasitic diseases, in cats from the north-west region of Portugal. For this purpose, 97 faecal samples were collected from cats at risk of being infected by Aelurostrongylus abstrusus in an animal shelter and in a municipal facility. Using the Baermann–Wetzel coprological technique, faecal shedding of first stage larvae (L1) was detected in 17.4% of the cats. Based on this result, it can be concluded that this lungworm infection seems to be common among feral cats in the north-west region of Portugal, in spite of the fact that clinical aelurostrongylosis is not frequently diagnosed by feline practitioners in the area. This parasitic disease should be included in the differential diagnosis of cats presenting with coughing or dyspnoea, and it also should be extended to asymptomatic animals with pulmonary nodules detected by image diagnosis.

Comparison of three different techniques to diagnose Fasciola hepatica infection in experimentally and naturally infected sheep.

The aim of this study was to compare three different techniques for the early diagnosis of the infection by Fasciola hepatica in experimentally and naturally infected sheep. The experimental group consisted of 7 sheep infected with 200 metacercariae; faecal samples were taken weekly until 12 week post-infection (wpi). Under natural conditions, 45 individual faecal samples and 2 pools of faeces were collected from three different flocks with a history of F. hepatica infection. The results obtained by a coprological method were compared with a commercial immunoassay and with two PCR assays in faecal samples. Faecal eggs were detected by 9 wpi in experimental infection. On the other hand, only 24 out of 45 sheep were positive in naturally infected flocks. By means of a sandwich-ELISA kit, the infection was first detected by 4 wpi in the 57.1% experimentally infected sheep and this percentage reached 100% by 8 wpi. All naturally infected animals were positive with this method. Regarding PCR, a specific 423 bp fragment of mitochondrial DNA was amplified in faecal samples. The F. hepatica infection was detected from 3 wpi with a standard PCR, and from 2 wpi with a nested-PCR. Only 37 sheep out of 45 were positive by the standard PCR although the infection was diagnosed in all animals by the nested-PCR. In conclusion, the sensitivity of the nested-PCR described in our study is higher than the detection of eggs in faeces as well as the commercial immunoassay. Moreover, no cross reactions were described with gastrointestinal nematodes.

Clinical evaluation and antibody responses in sheep after primary and secondary experimental challenges with the mange mite Sarcoptes scabiei var. ovis

In this work the clinical evolution and the specific serum IgG and IgE antibody responses in sheep after primary (n=10) and secondary (n=4) experimental challenges with the mange mite Sarcoptes scabiei var. ovis were studied. The primary infection was characterized by the development of mange lesions in all sheep, a detection of live S. scabiei mites in 70% skin scrapings taken in week 10 post-challenge (PC), strongly raised and sustained specific IgG levels and a more moderate but continuous rise in specific IgE levels. Seroconversion was detected for IgG and IgE by ELISA in 90% and 60% of the sheep in week 8 PC, respectively. By Western-blotting (WB), ten IgG-reactive bands (36-120 kDa) and four IgE-reactive bands (90-180 kDa) were observed in week 8 PC. Following the secondary challenge the ewes developed a smaller area of mange lesion than that seen following primary challenge and live S. scabiei mites were not detected in skin scrapings collected in week 8 PC, suggesting that sheep had developed immunity to re-infection. Compared to primary infection, the specific IgG secondary antibody levels were transient, but in contrast there was an anamnestic IgE response, resulting in an elicitation of specific serum IgE levels in week 2 PC significantly higher than those demonstrated after primary infection. WB analysis revealed one additional IgG-reactive band (180 kDa) and no additional IgE-reactive bands. Determining the immunodiagnostic or vaccination value of the IgG-reactive antigens and IgE-reactive allergens detected requires further studies.

Appetite depression in sheep experimentally infected with Fasciola hepatica L.

The purpose of this study was to determine the effects of experimental fasciolosis at various stages of development on the daily food intake of sheep. Five male Churra sheep, 4 months of age, were infected orally with 300 Fasciola hepatica metacercariae over a 30 day period. There was a significant increase in serum glutamate dehydrogenase (GLDH) activity from 40 days post-infection and in aspartate aminotransferase (AST) activity from 60 days post-infection. Both enzyme activities reached maximum levels in the serum of infected animals at 80 days and then progressively decreased. Serum gamma-glutamyltransferase (GGT) activity was significantly increased from 80 to 120 days post-infection. Glycaemia was significantly decreased from 60 days post-infection. The average daily food intake was shown to steadily decrease until approximately 100 days. The coincidence of decreased food intake with the period of significant increase, both in AST and GLDH activities, indicated that damage caused around the time of migration of immature flukes through the liver parenchyma may be involved in appetite depression.

Seroprevalence of Fasciola hepatica infection in sheep in northwestern Spain

To estimate the prevalence ofFasciola hepatica infection in sheep in the León province (northwestern Spain), we conducted a survey between October 1992 and May 1993. A total of 767 samples of feces and serum were collected from sheep over 1 year of age belonging to 152 flocks randomly selected from the 4 natural regions of León province. Samples were analyzed by a standard coprological sedimentation method and an indirect enzyme-linked immunosorbent assay (ELISA) using excretory-secretory products fromF. hepatica as the antigen. The results showed the feasibility of using the indirect ELISA to facilitate the serodiagnosis of ovine fasciolosis in seroepidemiology studies (95% sensitivity and >99% specificity). No serological cross-reaction with infection by the trematodeDicrocoelium dendriticum was found. Furthermore, a statistically significant association was demonstrated between the mean flock prevalence results as determined by ELISA (77.6%) and by coprological examination (23.7%;P<0.001). Differences in the results obtained by the two diagnostic methods could have been due to fluctuations in the numbers of fluke eggs detected in feces and to the persistence of specific antibodies in serum after and efficacious fasciolicide treatment. The median number ofF. hepatica eggs detected per gram of feces was 10 (range, 5–450 eggs/g feces). The geographical distribution ofF. hepatica infection in León province was similar in all natural regions, probably due to the observation that meteorological conditions are not limiting for the maintenance of the parasite life cycle in any area of the province and to the abundance of irrigated areas together with the lack of planned control strategies. No significant association between trematode infection and sheep breed, flock size, or number of treatments was found, but the results showed a significant association between infection and untreated sheep (P<0.05).To estimate the prevalence ofFasciola hepatica infection in sheep in the Leon province (northwestern Spain), we conducted a survey between October 1992 and May 1993. A total of 767 samples of feces and serum were collected from sheep over 1 year of age belonging to 152 flocks randomly selected from the 4 natural regions of Leon province. Samples were analyzed by a standard coprological sedimentation method and an indirect enzyme-linked immunosorbent assay (ELISA) using excretory-secretory products fromF. hepatica as the antigen. The results showed the feasibility of using the indirect ELISA to facilitate the serodiagnosis of ovine fasciolosis in seroepidemiology studies (95% sensitivity and >99% specificity). No serological cross-reaction with infection by the trematodeDicrocoelium dendriticum was found. Furthermore, a statistically significant association was demonstrated between the mean flock prevalence results as determined by ELISA (77.6%) and by coprological examination (23.7%;P<0.001). Differences in the results obtained by the two diagnostic methods could have been due to fluctuations in the numbers of fluke eggs detected in feces and to the persistence of specific antibodies in serum after and efficacious fasciolicide treatment. The median number ofF. hepatica eggs detected per gram of feces was 10 (range, 5–450 eggs/g feces). The geographical distribution ofF. hepatica infection in Leon province was similar in all natural regions, probably due to the observation that meteorological conditions are not limiting for the maintenance of the parasite life cycle in any area of the province and to the abundance of irrigated areas together with the lack of planned control strategies. No significant association between trematode infection and sheep breed, flock size, or number of treatments was found, but the results showed a significant association between infection and untreated sheep (P<0.05).

Serum and bile antibody responses (IgG and IgA) during subclinical Fasciola hepatica infection in sheep

The kinetics of serum and bile immunoglobulins (IgG and IgA) directed against Fasciola hepatica in the course of subclinical infection induced experimentally was investigated in sheep. Serum activities of glutamate dehydrogenase and gamma-glutamyltransferase were used as markers of the different fluke stages during infection and associated liver damage. Specific serum and bile immunoglobulins followed a similar kinetic pattern, increasing progressively from infection throughout the prepatent period and tended to decrease when adult flukes became established in the bile duct. IgA titres were lower than those of IgG. Specific IgG and IgA bile titres reached maximum values at 14 weeks postinfection that were considerably lower than the serum titres during the whole experimental period. The major bile immunoglobulins are probably derived directly from plasma. The immunoglobulin kinetic pattern could be related to changes in serum liver enzyme activities.

The diagnosis of fasciolosis in feces of sheep by means of a PCR and its application in the detection of anthelmintic resistance in sheep flocks naturally infected

The aim of this study was to develop a PCR for the diagnosis of Fasciola hepatica infection in feces of sheep based on the ribosomal internal transcribed spacer. Detection of infection was possible from the second week post-infection in experimentally infected sheep by amplification of a 292bp fragment. This PCR was employed for the detection of anthelmintic resistance (AR) in naturally infected sheep flocks, and results were compared with techniques such as the fecal egg count reduction test (FECRT) and the copro-antigen reduction test (CRT). The FECRT was carried out in two flocks, Santillan de la Vega (SV) and Corullón (CR), with sheep treated with albendazole (ABZ), clorsulon (CL), or triclabendazole (TCBZ). Feces were collected from individuals on days 0, 7, 15, and 30 post-treatment (pt). The FECRT showed adult F. hepatica to be resistant to ABZ and CL in both flocks. All parasite stages in the SV flock were susceptible to TCBZ, while in the CR flock, adult flukes showed resistance and immature forms were susceptible to the treatment. To compare FECRT and the PCR results, we calculated the percent of positive sheep on day 1 pt. In both flocks, the percent positive sheep was consistently higher by PCR than by sedimentation, confirming that the PCR is a more sensitive method of diagnosing infection and therefore to detect the resistance in infected animals. The CRT was carried out in the SV flock using a sandwich ELISA kit. The percent of sheep found positive by PCR was higher than with ELISA. Comparison of FECRT, CRT, and PCR for the detection of AR showed PCR to be the most sensitive.