Traumatic myiasis by Wohlfahrtia magnifica in sheep flocks from southeastern Spain: prevalence and risk factors.

Wohlfahrtia magnifica (Diptera: Sarcophagidae) is an obligate myiasis-causing fly of livestock that is widely distributed throughout the Mediterranean basin. A total of 73 683 sheep from 122 flocks in Albacete Province (southeastern [SE] Spain) were examined to detect active traumatic myiasis. The influence of several individual and flock factors on the prevalence was also assessed. The overall flock prevalence of traumatic myiasis was 95.9%, with an individual prevalence of 7.1%. Wohlfahrtia magnifica was identified in all of the positive animals except one that was infested by Lucilia sericata (Diptera: Calliphoridae). Adults of both genders showed a higher risk of infestation than juveniles, whereas males of all ages displayed an increased risk of infestation than females of all ages; the existence of a lambing building on the farm, poor husbandry facilities and the location area were also identified as risk factors. Prevalence was highest in the summer, and the fly season lasted from March to November. Genitalia were the main location of infestation in males (94.4%) and females (76.3%). Our results reveal that traumatic myiasis by W. magnifica is widespread in southeastern Spain, hence preventive measures minimizing the attractiveness of sheep to gravid flies are necessary to avoid health and welfare problems and significant production losses in sheep flocks.

Use of a crude extract or purified antigen from first-instar cattle grubs, Hypoderma lineatum, for the detection of anti-Hypoderma antibodies in free-ranging cervids from southern Spain.

During the 2003-2005 hunting seasons, a total of 120 Cervidae, including 39 red deer (Cervus elaphus hispanicus) and 81 fallow deer (Dama dama), were examined for subcutaneous myiasis. Animals were shot from January to June in southern Spain. Specific antibodies against Hypodermatinae (Diptera: Oestridae) were detected by indirect enzyme-linked immunosorbent assay (iELISA) using a crude larval extract (CLE) and a purified antigen [hypodermin C (HC)] obtained from first instars of Hypoderma lineatum (De Villers) (Diptera: Oestridae). Hypoderma actaeon Brauer was the only species detected in this study, which represents the first confirmation of this species in fallow deer from Spain. The overall prevalence of animals presenting subcutaneous larvae (14.2%) was considerably lower than the prevalences determined by iELISA with CLE (43.3%) and HC (40.0%). Red deer showed a higher prevalence of Hypoderma than fallow deer. The concordance between larval examination during the hunting season and iELISA using both antigens was low, whereas the concordance between the CLE and HC ELISAs was good. Larval antigens obtained from H. lineatum constitute a good tool for the diagnosis of H. actaeon in Cervidae, especially when the hunting season does not coincide with the maximum presence of larvae on the back.

Efficacy of anthelminthic control programs against natural Muellerius capillaris infection in sheep in the north-west of Spain. Effect on blood gases and pH in venous blood samples.

The field efficacy of a single dose treatment against natural M. capillaris infection using different anthelmintic drugs, extensively employed in ovine parasite control programs in Galicia (N.W. Spain), and the effect of protostrongylid infection on ovine respiratory functions, were evaluated. Five groups (n = 5) of ewes were used in this study; animals were treated with injectable ivermectin 10.2 mg/kg), levamisole (7.5 mg/kg) and albendazole (5 mg/kg) and monitored at 0, 7, 21, 42 and 63 days posttreatment (d.p.t.) by enumeration of the lungworm larvae per gram of faeces (l.p.g.) and determination of gas tension and pH in venous blood using an i-Stat portable clinical analyzer. No statistical difference was found either in larval elimination between untreated and treated groups or in the reduction in larval counts in all of the treated groups. A significant increase in partial oxygen tension (pO2) and saturation (sO2) between day 0 and 7 p.t. was observed in all treated animals. These values decreased significantly at day 21 to previous levels. There were no statistical differences in blood gases between uninfected and treated groups. We can conclude that under Galician field conditions, parasitic control programs are not totally effective against M. capillaris infection.

Cytokine expression in bovine PBMC cultures stimulated with Hypoderma lineatum antigens.

Hypoderma antigens are involved in host inflammation and immune response, conditioning larvae survival. In this study, peripheral blood mononuclear cell (PBMC) cultures from Hypoderma sensitized and unsensitized cattle were performed to determine the effect of H. lineatum antigens and incubation time (18, 24, 48 h) on IFN-γ, TNF-α, IL-10 and IL-4 mRNA gene expression determined by RT-qPCR. TNF-α and IL-4 gene expression were higher in Hypoderma previously sensitized PBMCs, suggesting that a mixed Th1/Th2 response may play a significant role in host defence reactions against Hypoderma exhibited by previously infested cattle. Incubation time had a significant effect on IL-10 and TNF-α gene expression, which decreased over time. Regarding to H. lineatum antigens, the crude larval extract and the purified fraction hypodermin B (HB) produced a significant reduction of the mRNA expression levels of the proinflammatory cytokine, IFN-γ; moreover, the HB had a stimulating effect on the mRNA gene expression of the anti-inflammatory cytokine IL-10, demonstrating that the parasite would modulate the host defence mechanisms by avoiding harmful immune responses that would limit its survival into the host tissues.

Lesser housefly (Fannia canicularis) as possible mechanical vector for Aleutian mink disease virus.

Flies are known vectors for a variety of infectious diseases in animals. In fur mink farming, one of the most severe diseases is Aleutian disease, which is caused by the Aleutian mink disease virus (AMDV). The presence of large fly populations is a frequent issue in mink farms; however, no studies assessing their role as AMDV carrier vectors have been conducted to-date. In order to determine the presence of AMDV in aerial flies from an infected mink farm, flies (n = 254) and environmental swab samples (n = 4) were collected from two farm barns. Fannia canicularis (L.) (Diptera: Muscidae) represented more than 99% of the fly population. One hundred and fifty specimens of this species were divided into pools of ten flies and analysed by qPCR, and positive samples were further sequenced. All fly pools and environmental samples tested positive for AMDV, and sequence analysis revealed identical genotypes in both types of samples. This is the first report of AMDV contamination in flies from mink farms, suggesting that F. canicularis may act as an AMDV vector. These results may be of interest for epidemiological studies and also for the improvement of control measures against this virus in mink farms.

Bronchopulmonary helminths of roe deer (Capreolus capreolus) in the northwest of Spain.

From 1993 to 1995, 148 hunter killed roe deer (Capreolus capreolus L.) from game reserves in Lugo (northwestern Spain) were examined for lungworm infection. The overall prevalence of infection was high (66.2%). Infections were comprised to two species, Varestrongylus capreoli and Dictyocaulus noerneri with a prevalence of 62.0 and 18.2%, respectively. Significant differences in the prevalence and larval burdens in lungs and faecal samples were observed between different locations. The highest overall prevalence of lungworm infection was observed in the large reserve at Ancares (78%) in comparison to that in smaller reserves (61.7%). Considering that the species recorded in this study are highly host-specific, it is unlikely that roe deer represent a significant reservoir of lungworm transmissible to domestic ruminants in northwestern Spain.

Joint larval development of Cystocaulus ocreatus/Muellerius capillaris and C. ocreatus/Neostrongylus linearis (Nematoda) in six species of Helicidae (Mollusca) experimentally infected).

This is the first study on the experimental susceptibility of the following species of molluscs: Cernuella (X.) cespitum arigonis, Helicella (H.) itala, Helicella ordunensis, Cochlicella barbara, Cepaea nemoralis and Helix (C.) aspersa, as intermediate hosts for the combination of both C. ocreatus and M. capillaris, pulmonary parasites in ruminants. Furthermore, the larval development of C. ocreatus and N. linearis, the two taken together, has been followed in Cernuella (X.) cespitum arigonis, H. ordunensis and C. nemoralis. Approximately 40 specimens of each of the above-mentioned species of molluscs were infected with the parasites listed. Bearing in mind the results obtained, we believe that while Cernuella (X.) cespitum arigonis, H. ordunensis, C. nemoralis, C. barbara and Helicella (H.) itala are suitable intermediate hosts for the larval combination of C. ocreatus and M. capillaris, the same cannot be said of Helix (C.) aspersa. Likewise, the first 3 species of molluscs quoted are ideal for the joint larval development of C. ocreatus and N. linearis. It seems that double infections favour larval development.