Several studies show the presence of protozoa of the genus Nematopsis Schneider, 1892, in many species of bivalves. The pathogenicity of this Apicomplexa is still much debated, which is possibly related to the parasitism degree and host habitat. In this context, this study investigated parasitism by Nematopsis sp. in Mytella guyanensis (Bivalvia: Mytilidae) in a mangrove of the Marine Extractive Reserve Baía do Iguape, Bahia, Brazil. The collections were made monthly, from March 2014 to March 2015, consisting of 30 adults with shell height above 40 mm per month, totaling 360 specimens. The specimens were measured, weighed, opened, and macroscopically examined for identifying parasites and/or signs of morphological changes. After that, they were fixed in Davidson’s solution and processed according to classical histological techniques, with inclusion in paraffin, obtaining 5 μm-thick sections by microtomy, and stained by Harris’ Hematoxylin and Eosin (HE). The water temperature ranged from 25.5 to 33.6 ºC and the salinity from 21.1 to 34.3 Practical Salinity Units (PSU). The specimens measured between 41.1 and 68.6 mm and had an average weight of 7.24 g. Macroscopically, there was no presence of the parasite or any morphological changes related its presence. The frequency percentage of Nematopsis sp. was 99.45%. The mantle was the organ with the highest frequency of infection (46.26%), followed by the gonads (18.36%). Among the analyzed organs, all presented the parasite and, in a few severely infected cases, microscopical changes were observed in the mantle conformation. The infection intensity for most of the sessions analyzed was 1 to 3 oocysts/phagocyte; however, in one of the sessions, 9 oocysts/phagocytes were recorded. The parasite had a negative correlation with salinity. The high frequency of Nematopsis sp. should be considered for the sustainability of natural stocks, especially if such parasitism occurs simultaneously with other pathogens and stressful environmental conditions.

Parafasciolopsis fasciolaemorpha is a liver fluke typically parasitising moose in Central and Eastern Europe. The aim of our studies was to describe a case of fatal moose parafasciolopsosis, with special emphasis on the histopathological changes caused in the liver tissue by around 10,000 flukes. A male moose, found dead in Polesie National Park, eastern Poland, was subjected to parasitological necropsy. Macroscopic and histopathological examination of the liver was performed. Over 10,000 flukes identified as P. fasciolaemorpha were isolated from the liver parenchyma. Histopathological examination of the liver revealed the presence of multiple cavities, which were filled with flukes and cellular detritus and encysted with a layered capsule of connective tissue. Extensive liver fibrosis with signs of incomplete septal cirrhosis was also observed. Parafasciolopsosis with accompanying diarrhoea was the most probable reason for the moose’s death. However, it is possible that most moose are able to survive extremely intensive P. fasciolaemorpha infection by formation of extensive fibrosis, which isolates flukes from the liver parenchyma and therefore retards the failure of the organ. To the best of our knowledge, this is the first histopathological description of changes in the liver of a moose infected with P. fasciolaemorpha.

To determine resistance of small strongyles to albendazole, 3 female ponies (group 1) were grazed on a pasture from May to November 1985 and were treated with 7.5 mg of albendazole/kg of body weight, PO, 2 days before turnout in May and again in June and in July. Three other female ponies (group 2) grazed on a similar pasture from May to July, were treated with 7.5 mg of albendazole/kg, and were removed to another pasture until November. In December, ponies from both groups were treated with 7.5 mg of albendazole/kg, and 8 days later, they were euthanatized and necropsied for a critical test. Worm egg counts in the ponies' feces revealed that the May treatment of group 1 and the July teatment of group 2 were more effective than were later treatments. Numbers of small strongyles were higher in group 1 than in group 2. Efficacy of treatment against all developmental stages of small strongyles were higher in group 2 than in group 1. Efficacy was low in both groups against parasitic 3rd- and 4th-stage larvae. Fifteen species of small strongyles were identified at necrospy. Efficacy was limited against adult Cyathostomum coronatum, Cya labratum, Cylicostephanus calicatus, and Cyl poculatus in both groups; Cylicocyclus nassatus, Cyl minutus, and Cyl longibursatus in group 1; and Cya labiatum in group 2. Efficacy was 100% against Cya catinatum, Cyl goldi, and 5 other species that were found in low numbers.

The male, female, nymph, and larva of Haemaphysalis (Rhipistoma) norvali sp. n., are described and compared with other members of the H. (R.) spinulosa group. Adult H. (R.) norvali parasitize the southern African hedgehog, Erinaceus frontalis Smith, in Matabeleland, Zimbabwe. Immatures were reared on a laboratory rabbit.

In the first of 2 separate trials, the efficacy of febantel, given at a dosage of 5 mg/kg of body weight, was assessed in calves with 60-day experimentally induced Bunostomum phlebotomum infection. Ten calves were given febantel paste, and 10 were given the vehicle only. All 20 calves were necropsied 7 days after cessation of treatment. Compared with untreated calves, febantel-treated calves harbored 99.4% fewer nematodes. In the second trial, the efficacy of ivermectin, given as a paste formulation at a dosage of 0.2 mg/kg, was assessed in calves with experimentally induced B phlebotomum infection. Ivermectin was given at 18 (n = 6) and 60 (n = 6) days after infection. At each treatment date, 3 additional calves were given vehicle only. At 67 days after infection, all calves were euthanatized. Efficacies of ivermectin against 18- and 60-day infections were 100 and 99.8%, respectively. Both anthelmintic preparations were easily administered, and adverse reactions were not observed.

Observations were completed over an 18-year period (1966 through 1983) in Thoroughbred mares (15/year) and yearlings (11 to 24/year) on a farm where benzimidazole-resistant small strongyles had emerged previously (1962 to 1965). This farm was operated as a closed, nonboarding type, which included a racing stable for its home-bred foals. At 2-week intervals, counts of worm eggs per gram of feces (EPG) and larvae per gram of feces were done to monitor strongyle infections and efficacies of bimonthly (every 8 weeks) antiparasitic treatments that were administered by stomach tube or were fed (dichlorvos pellets) to 1 group of yearlings during a 7-year period (1970 through 1976). The study included several drugs or mixtures, including thiabendazole (TBZ), phenothiazine (PTZ) + piperazine (PPZ)-carbon disulfide (CS2) complex, PTZ + PPZ + trichlorfon (TCF), dichlorvos, and pyrantel pamoate. These were used selectively in treated subgroups (usually 3/year) of mares and yearlings. The horses in drug treatment subgroups grazed together on common pastures; thus, efficacy comparisons between drugs were limited or nullified. However, annual mean EPG and larvae per gram of feces counts of mares and yearlings tended to increase over time, and for the yearlings treated with TBZ + PPZ and PTZ + PPZ-CS2, the buildup of these mean counts was statistically significant (P less than 0.05 for regression coefficients). These trends of annual mean counts to increase were a general index of loss of anthelmintic activity of the 3 drug mixtures containing PPZ (TBZ + PPZ, PTZ + PPZ-CS2, and PTZ + PPZ TCF); however, trends were indicated more definitively by 2 other indices: (1) loss of effectiveness in reduction of EPG counts 2 weeks after treatment and (2) decrease in performance for complete clearance of strongyle eggs (EPG, 0) 2 weeks after treatment. Loss of effectiveness over time was statistically significant (P less than 0.001) for the mares only when data was pooled for all 3 treatments (TBZ + PPZ, PTZ + PPZ-CS2, and PTZ + PPZ + TCF); however, the decreasing effectiveness was statistically significant (P less than 0.05) for TBZ + PPZ and PTZ + PPZ-CS2 treatment of yearlings. Statistically, clearance performance in mareswas significant for treatments with TBZ + PPZ (P less than 0.003) and PTZ + PPZ + TCF (P less than 0.005) and approached significance with PTZ + PPZ-CS2 (P greater than 0.06). Clearance performances in yearlings were highly significant (P less than 0.0003) for treatments with TBZ + PPZ and PTZ + PPZ-CS2. These analyses of data indicate that the intense and prolonged (greater than or equal to 18 years) use of PPZ as a common component in several of the drug mixtures had resulted in the selection of a segment of small strongyles resistant to PPZ. Multiple resistance of this population of small strongyles includes several drugs: PTZ, the benzimidazoles (except oxibendazole and albendazole), possibly pyrantel, and PPZ. Side effects of drug treatments were not apparent during the prolonged period of this study.

Limited information is available regarding gastro-intestinal (GI)parasitic infections in Malaysian swine populations. Hence, the present study aims to determine the prevalence of GI parasites in two swine populations in Malaysia, using formalin-ether concentration technique. In the present study, three helminths and two protozoa were detected in 91 swine rectal fecal samples. The zoonotic transmissible protozoan, Balantidium coli (22.0%) had the highest infection rate, followed by strongyle (4.4%), Entamoeba spp. (2.2%), Fasciolopsis spp. (1.1%) and Trichuris suis (1.1%). The co-infection between T. suis and B. coli was also found in this study.