In vitro and in vivo action of Piptadenia viridiflora (Kunth) Benth against Haemonchus contortus in sheep

Anthelminthic resistant populations of Haemonchus contortus are a major problem in sheep rearing, but plant extracts may offer viable alternative treatments. In our preliminary studies, Piptadenia viridiflora was frequently selected by sheep grazing in the Cerrado. The present research evaluated its in vitro and in vivo anthelmintic activity. The HPLC chromatograms of P. viridiflora aqueous extract (AE) and ethanolic extract (EE) showed the presence of flavonoids. The total condensed tannin (proanthocyanidin) was 0.2 and 1.01% in AE and EE, respectively. In an egg hatching inhibition (EHI) test, the LC90 of AE was 2.4mg/mL, and, of EE, was 2.1mg/mL. After tannin extraction, higher EHI and lower LC90 were observed. In a larval development inhibition test, the LC90 of AE was 13.66mg/g of fecal culture. The highest dose of AE administered to mice (203.0mg/kg bw) was well tolerated, suggesting low toxicity. In vivo, AE was orally administered to lambs at 283mg/kg bw, and, at weeks one, two, and three post-treatment, the mean fecal egg count (FEC) was significantly lower than in untreated lambs (P<0.05). Blood parameters were normal and similar in untreated and treated sheep. For all lamb groups, the mean total serum protein was significantly higher at week two post-treatment than at other evaluated periods (P<0.05). Piptadenia viridiflora extracts had low condensed tannin content and exhibited high anthelminthic efficacy in vitro and significantly reduced FEC. Tannins were not shown to be the principal components affecting EHI, hence it is necessary to isolate and characterize the principal active P. viridiflora compounds, and to assess their possible synergism.

Rupture of the thoracic aorta associated with experimental Angiostrongylus vasorum infection in a dog

This note describes the sudden death of a dog by the rupture of the thoracic aorta caused by the presence of Angiostrongylus vasorum. A female mongrel canine with a history of weight loss and exhaustion died two hours after clinical examination. At necropsy, performed one hour after death, showed the presence of clotted blood in the thoracic cavity. Haemothorax was diagnosed. The thoracic aorta wall was thin, congested and an abnormal hole in the wall was detected approximately 0.5 cm from the entrance to the diaphragm. From clotted blood collected from the thoracic cavity, 224 first stage larvae (L1) and 15 adults of Angiostrongylus vasorum were recovered alive. Also, from a blood clot found in the aorta, four adult females and 47 L1 larvae were recovered alive. Possibly, this parasite was responsible for the aortic rupture and death of the animal.

Cytological and parasitological analysis of bronchoalveolar lavage fluid for the diagnosis of Angiostrongylus vasorum infection in dogs

Bronchoalveolar lavage (BAL) is a procedure that retrieves cells and other elements from the lungs for evaluation, which helps in the diagnosis of many pulmonary diseases. The aims of this work were to perform this procedure in dogs in the acute and chronic phases of an Angiostrongylus vasorum infection for cytological analysis and to evaluate the potential of this technique as a diagnostic method for this lung-heart worm. The BAL procedure was performed through the use of an endotracheal tube on seven A. vasorum infected dogs and on five non-infected dogs lined as a control group. Sixty days post-infection (dpi) active and live larvae were retrieved from the bronchoalveolar fluid (BALF) of all infected dogs. Furthermore, in one animal it was possible to retrieve larvae in its BALF before the pre-patent period. This work reports that the A. vasorum infection resulted in an increase of relative neutrophils and eosinophils counts. In contrast, there was a significant decrease in the alveolar macrophage relative count in infected animals from 60 to 330 dpi. This study shows that the BAL is an accurate technique for the diagnosis of canine angiostrongylosis. Moreover, the technique allows us to retrieve cells and other elements that line the lung surface for cytological evaluation, which provides information about inflammatory diseases, and the diagnosis and prognosis of pulmonary parasites such as A. vasorum.

Larval output of infected and re-infected dogs with Angiostrongylus vasorum (Baillet, 1866) Kamensky, 1905

Canine angiostrongylosis is a nematode infection in domestic dogs and wild canids. A natural infection in a domestic dog frequently leads to pneumonia, loss of physical performance, coughing, anemia, cardiac insufficiency, pulmonary fibrosis and death. The main diagnostic method is based on the finding of Angiostrongylus vasorum first-stage larvae (L1) in infected dog feces. With this objective, 11 experimentally exposed to 100 third-stage larvae (L3) per kilogram of body weight (mean = 885.45 L3/animal; S.E. = 77.7). The animals were monitored for 300 days post-single-infection (PI) and the quantity of L1 output measured. Our results showed an irregular excretion of L1 and a variation in the pre-patent period (33-76 days) and the number of L1 excreted by individual animals (1-1261 L1/g). After 300 days PI, five dogs were exposed a second time and monitored for 300 days post-re-infection (PRI) (=600 days PI). The quantity of L1 output demonstrated that double exposed dogs also presented an irregular excretion of L1 but a smaller variation in the number of L1 excreted by individual animals (4-550 L1/g).

Effect of Angiostrongylus vasorum infection on Biomphalaria tenagophila susceptibility to Schistosoma mansoni

Concomitant infection with different parasites may be a helpful laboratorial strategy leading to the better understanding of the mechanisms used by the internal defense system (IDS) of Gastropoda to deal with helminth infection, such as Schistosoma mansoni. This work reports the effect of co-infection of Angiostrongylus vasorum and S. mansoni in hemocyte activity and in the outcome of infection. The simultaneous infection resulted in an increase of snail susceptibility to S. mansoni. In contrast, snails infected with both parasites, 15 days apart, did not show differences in the susceptibility compared to a single parasite infection. The increased susceptibility was measured by the significantly higher number of migrating sporocysts, higher percentage of snails shedding cercariae, higher number of cercariae shed and higher mortality in the experimental group that were simultaneously infected with A. vasorum and S. mansoni, when compared to snails infected only with S. mansoni. Snails simultaneously infected with A. vasorum and S. mansoni showed lower hemocyte activation during the first few days of infection, compared to activation induced only by A. vasorum infection. Between 5 and 15 days post-infection (dpi), granulocyte number and nitric oxide (NO) contents of simultaneously infected snails were lower than the S. mansoni-infected snails. Based on the results, we suggest that differences in the level of hemocyte response could explain the increased S. mansoni susceptibility observed in snails simultaneously infected with both parasites. However, when S. mansoni infection occurred after A. vasorum larvae are completely encapsulated, the response against S. mansoni was not altered, and therefore there were no differences in the susceptibility level.

Biochemical serum profiles in dogs experimentally infected with Angiostrongylus vasorum (Baillet, 1866)

The biochemical profiles of crossbred dogs experimentally infected with the parasite Angiostrongylus vasorum were studied. Two groups of five dogs were experimentally inoculated with 50 and 100 third stage infective larvae (L₃) of A. vasorum per kilogram of body weight. A third group of five uninfected animals were used as control. Serum from these animals were used for biochemical tests to measure total and fractioned proteins, urea, creatinine and to determine the activities of aspartate (AST), alanine (ALT) aminotransferase, gamma-glutamyl transferase (GGT), alkaline phosphatase (PAL) and creatine kinase isoenzyme MB (CK-MB). The α-1, α-2 and β-globulins fractions showed alterations during acute phase of the infection. No modifications were observed in the biochemical profiles of ALT, AST, GGT, PAL, urea and creatinine. CK-MB was shown to be a good early indicator of cardiac injury in dogs experimentally infected with A. vasorum.

Evaluation of the prophylactic effect and curative efficacy of fipronil 1% pour on (Topline®) on post-castration scrotal myiasis caused by Cochliomyia hominivorax in cattle

A field trial was carried out during a summer-fall period on a commercial beef cattle farm in Minas Gerais State, located in the Southeast of Brazil. In order to evaluate the prophylactic effect and the curative efficacy of fipronil in a 1% solution, 200 Zebu crossbred bulls, with ages varying from 20 to 30 months and weights from 233 to 362 kg, were selected. The bulls were assigned by ranked pair to an untreated control group (A) or to a treated group (B), resulting in 100 animals per group. All experimental animals were surgically castrated on day 0, following routine procedures. After castration all animals in the group B were treated with 10 mg/kg bw of a 1% fipronil solution, topically on the dorsal mid-line. The wounds were individually inspected on days: 2, 4, 7, 10, 14, 17, 21, 28 and 35. After castration the animals were naturally exposed to Cochliomyia hominivorax and remained in the same pasture throughout the trial. Among the animals in the control group, 83 were observed to harbor C. hominivorax eggs, with a total of 97 ovipositions, and among those 73 animals had active myiasis. In group B (fipronil 1%), 66 animals showed C. hominivorax eggs, with 92 ovipositions and five animals with active myiasis. Most ovipositions and active myiasis were detected until seven days post-castration for both groups. Wound parasite infestation evidenced bleeding, serous purulent exudation and presence of active C. hominivorax larvae. Treatment with fipronil 1% had a prophylactic effect on scrotal wounds against the development of C. hominivorax larvae in more than 95% of the treated animals for up to 17 days after castration. The treatment showed partial protection of 66% and 50% on days 21 and 28 post-treatment (pt), respectively. Three animals from the control group and one from the treated group showed active screwworms on day 21 pt, and one animal from the treated group and two from the control group also presented C. hominivorax larvae on scrotal wounds on day 28 pt. By the end of the observation period (day 35 pt), the castration wound had healed in all animals. All experimental animals presenting scrotal wounds infested with C. hominivorax larvae were treated with a 1% pour-on formulation of fipronil, on the same day that infestation was observed. Active C. hominivorax larvae were not seen during the monitoring period immediately after treatment. The curative efficacy of fipronil 1% against C. hominivorax larvae infestation in castration wounds was 100%.

Ectopic location of adult worms and first-stage larvae of Angiostrongylus vasorum in an infected dog

A mongrel dog with angiostrongylosis died suddenly and was submitted to necropsy. Post-mortem findings showed adult worms in ectopic locations. This is the first report of Angiostrongylus vasorum adult worms being found within the pericardial sac and in the lumen of the bladder of an infected dog. A total of 587 A. vasorum first-stage larvae were recovered from different organs and tissues after concentration using Baermann apparatus.

Population dynamics of Lymnaea columella and its natural infection by Fasciola hepatica in the State of Minas Gerais, Brazil

Studies on the population dynamics and natural infection of Lymnaea columella by Fasciola hepatica were carried out from September 1999 to December 2000 in a low-lying area near Itajubá in the Brazilian State of Minas Gerais. A total of 626 snails were collected monthly at nine different sites, counted, and dissected to search for larvae of F. hepatica. The highest populations of L. columella were reached in October of 1999 and August of 2000, and the highest natural infection rates of snails by F. hepatica were reached in September 1999 (5.2%) and July 2000 (3.9%). The removal by farmers of aquatic plants from the drainage furrows caused a drastic reduction in this snail population.

A method to obtain axenic Angiostrongylus vasorum first-stage larvae from dog feces

An improved method to obtain a large number of axenic larvae of Angiostrongylus vasorum from fecal samples was developed in the present study. The procedure here in reported consisted of obtaining larvae using a modified Baermann technique, followed by an additional filtration step. This isolation technique recovered almost 90% of the living larvae in a clean preparation. Isolated larvae were submitted to decontamination treatments with either sodium hypochlorite or antibiotic cocktail solutions. The axenic status, as confirmed by oral inoculation of decontaminated larvae into germ-free mice, was only achieved using larvae treated with 0.5% sodium hypochlorite solution for 10 min. The isolation and decontamination treatment did not affect larval viability. Treated larvae remained viable and infective to the invertebrate host.

Western blot analysis of the humoral response of dogs experimentally infected with Angiostrongylus vasorum (Baillet, 1866)

Seven cross-bred dogs were inoculated with Angiostrongylus vasorum and serum samples were analyzed using the enzyme-linked immunosorbent assay (ELISA) and Western blot (WB). ELISA detected specific antibodies anti-A. vasorum, from 14 to 28 days after inoculation (DAI) and persisted throughout the experiment. Using WB, the main antigens detected had molecular weight of approximately 115, 102, 86, 76, 69, 56, 41, 32, 28, 20-22 and 10kDa.

Hematological and coagulation profiles in dogs experimentally infected with Angiostrongylus vasorum (Baillet, 1866)

Hematological and coagulation profiles were studied in crossbred dogs experimentally infected with Angiostrongylus vasorum. Two groups of five dogs were experimentally inoculated with 50 and 100 third stage infective larvae (L(3)) of A. vasorum per kilogram of body weight. A third group of five uninfected animals was used as control. One sample of 10 ml of blood was collected from each animal on the 10, 20, 30, and 45 days after inoculation (dai) and at 30-day intervals thereafter for the remainder of the 210-day experimental period. The blood sample was used for the complete hemogram and platelet count, as well as measurements of prothrombin time, partial thromboplastin time and factors V and VIII. Anemia was observed in infected dogs, 6 weeks after the infection. The eosinophils presented peaks in four periods after infection. Thrombocytopenia became accentuated on the 72 dai. Decreased prothrombin time activity and increased partial thromboplastin time were observed at the 6 and 9 weeks after infection and decreased of factors VIII and V activities occurred from 4 to 6 weeks after infection. It may be conclude that infection by A. vasorum in dogs may cause a discrete anemia during the acute phase which is probably regenerative. In addition, important hemostatic alterations due to the infection suggest a chronic intravascular consumption coagulopathy.

Seasonal variation of Boophilus microplus (Canestrini, 1887) (Acari: Ixodidae) in cattle in Minas Gerais State, Brazil

The seasonal variation of the tick Boophilus microplus in the 'Região Metalúrgica' region of Minas Gerais state was studied using 26 Bos taurus (Holstein) x Bos indicus (Gir) calves, of which 16 animals were 3/4 Holstein x 1/4 Gir and 10 were 3/4 Gir x 1/4 Holstein. Monthly tick counts were made between March 1996 and March 1998 and, although B. microplus infestations occurred throughout the year, they were greater during the rainy season. Rainfall was the climatic factor that most affected the seasonal variation. The animals with a preponderance of Holstein blood presented infestations that were significantly (p < 0.05) greater than those of the other cross. Five of the animals (19.2%) maintained 45.5% of the parasite load of the entire group.

Strategic control of gastrointestinal nematodes in dairy calves in Florestal, Minas Gerais, Brazil

Following epidemiological studies of gastrointestinal helminthiasis in dairy cattle in Florestal County, Minas Gerais, 80 Swiss and crossbred Zebu x Holstein calves, 8-10-months old, were selected to test the efficacy of three treatment protocols using ivermectin for helminth control. The calves were treated in Brachiaria grass paddocks, naturally infected with Haemonchus, Cooperia, Oesophagostomum and Trichostrongylus species, and then divided into four groups of 20 animals each: group 1 was treated with 200 microg/kg body weight ivermectin in April (at the end of the rainy season) and October (beginning of the rainy season); group 2 was treated in April, August (middle of the dry season) and October; group 3 was treated in April, August, October and December (middle of the rainy season); and group 4 was left untreated as a control. The treatments effectively eliminated the worm burden only in groups 2 and 3 (p < 0.05), although the calves continued to excrete Cooperia eggs after each treatment with ivermectin.

Seasonal infection pattern of gastrointestinal nematodes of beef cattle in Minas Gerais State--Brazil

Tracer calves were used to assess the seasonality of infections of gastrointestinal parasites in beef cattle extensively raised at a farm in the State of Minas Gerais, Brazil. Tracer calves acquired infections during all months of the year, however, highest worm burdens were observed in the rainy season. The following nematode species were recovered from tracer calves: Cooperia punctata, C. spatulata, C. pectinata, Haemonchus similis, H. placei, Oesophagostomum radiatum, Trichostrongylus colubriformis, T. axei, Bunostomum phlebotomum and Trichuris discolor. Cooperia was most prevalent, representing 74.4% of the total of all nematodes recovered. This was followed by Haemonchus 19.2%, Oesophagostomum 4.5%, Trichostrongylus, Trichuris and Bunostomum, represented less than 1% of the total. Thirty Nellore cows with calves were used to evaluate the dynamics of the infections. The cows were the principal source of contamination to pasture and to infection of suckling calves during the pre-weaning period, and probably, also contributed to increased infection of weaned calves at the beginning of the rainy season. Strongyloides was the first infection observed in the calves. The peak egg count was observed in the 2nd month, however, all Strongyloides egg counts became negative in the 7th month. Strongylate nematode egg counts were low in calves from the 3rd month of age onward, and increased gradually until calves were 1 year old. A gradual reduction then occurred until the end of the trial. From the 3rd month onward Cooperia and Haemonchus infective larvae (L3) were most prevalent in fecal cultures. Fecal cultures after the 4th month also resulted in recoveries of Oesophagostomum, Trichostrongylus, and Bunostomum L3. Cooperia was the predominant genus in fecal cultures until the calves were 9 months old. After the calves were 9 and 12 months of age, L3 of Cooperia and Oesophagostomum, respectively decreased in prevalence. Trichostrongylus and Bunostomum L3 were only minimally present in the fecal cultures at this time.

Volatile cardioplegia: fast normothermic cardiac arrest induction and recovery with halothane in isolated rat hearts

To study the effect of halothane as a cardioplegic agent, ten Wistar rats were anesthetized by ether inhalation and their hearts were perfused in a Langendorff system with Krebs-Henseleit solution (36 degrees C; 90 cm H2O pressure). After a 15-min period for stabilization the control values for heart rate, force(T), dT/dt and coronary flow were recorded and a halothane-enriched solution (same temperature and pressure) was perfused until cardiac arrest was obtained. The same Krebs-Henseleit solution was reperfused again and the parameters studied were recorded after 1, 3, 5, 10, 20 and 30 min. Cardiac arrest occurred in all hearts during the first two min of perfusion with halothane-bubbled solution. One minute after reperfusion without halothane, the following parameters reported in terms of control values were obtained: 90.5% of control heart rate(266.9 +/- 43.4 to 231.5 +/- 71.0 bpm), 20.2% of the force (1.83 +/- 0.28 to 0.37 +/- 0.25 g), 19.8% of dT/dt (46.0 +/- 7.0 to 9.3 +/- 6.0 g/s) and 90.8% of coronary flow (9.9 +/- 1.5 to 9.4 +/- 1.5 ml/min). After 3 min of perfusion they changed to 99.0% heart rate (261.0 +/- 48.2), 98.9% force (1.81 +/- 0.33), 98.6 dT/dt (45.0 +/- 8.2) and 94.8% coronary flow (9.3 +/- 1.4). At 5 min 100.8% (267.0 +/- 40.6) heart rate, 105.0% (1.92 +/- 0.29) force and 104.4% (48.2 +/- 7.2) dT/dt were recorded and maintained without significant differences (P > 0.01) until the end of the experiment. These data demonstrate that volatile cardioplegia with halothane is an effective technique for fast induction of and prompt recovery from normothermic cardiac arrest of the rat heart.

Rupture of femoral artery in a dog infected with Angiostrongylus vasorum

A crossbred bitch, infected with Angiostrongylus vasorum, died on the 46th day post infection. Post mortem findings showed that the rupture of the femoral artery was the cause of death. A. vasorum was present in the femoral artery.

Occurrence of Angiostrongylus vasorum in the lungs of the Brazilian fox Dusicyon vetulus

Angiostrongylus vasorum infection was detected for the first time in eight foxes (Dusicyon vetulus) captured in the south of the State of Minas Gerais, Brazil. Two crossbred dogs were successfully infected orally with larvae from the foxes' faeces.

Transmission of Schistosoma mansoni under experimental conditions using the bovine--Biomphalaria glabrata-bovine model

Three calves experimentally infected with Schistosoma mansoni, and passing viable eggs in feces, as well as 5 normal calves (coming from a non-endemic area for schistosomiasis) kept as controls, were maintained in an enclosure (850 m2 in area). In this enclosure, a tank with water received 500 laboratory reared Biomphalaria glabrata. All the control calves were infected for a period ranging from 79 to 202 days after the beginning of the experiment, and afterwards presented viable S. mansoni eggs in feces. The mean worm recovery was 555. The snail population increased throughout the experimental period, showing a high number of B. glabrata infected with S. mansoni (42% on average). According to the present study, bovine has been suggested as having potentially a role in the maintenance of the life cycle of S. mansoni.

Prevalence of Cooperia punctata, C. pectinata and C. oncophora infections in dairy calves in Brazil

Cooperia is the most prevalent helminth parasitizing calves in Brazil. Three species of this genus occur most often: C. punctata, C. pectinata and C. oncophora. Six calves from dairy farms in the south of the State of Minas Gerais aged six to 15 months were killed and necropsied each month over a period of two years. The Cooperia species were identified, counted, and the numbers related to the calves' age. The worm burdens due to the three species of Cooperia were statistically different. C. punctata was the most prevalent species and had a positive correlation with the age of the calves; C. pectinata appeared with lower intensity but was always present, and C. oncophora was not found in calves older than 11 months. These results show the existence of different degrees of resistance to Cooperia species among calves as the three species did not behave similarly. It seems to be an acquired resistance. C. punctata appears to be less immunogenic than C. pectinata and C. oncophora. As C. punctata and C. pectinata are more pathogenic than C. oncophora, it seems that this pathogenicity can be related to immunogenic aspects associated with the species.

Schistosoma mansoni: on the possibility of Indian buffalo (Bubalus bubalis) being experimentally infected

Male Indian buffalo (Bubalus bubalis) calves were submitted to Schistosoma mansoni infection by percutaneous, oral and subcutaneous routes. No worms or eggs were found in four of the animals tested. Bubalus bubalis appears to be refractory for S. mansoni.