The prevalence of anthelmintic resistance in nematode parasites of sheep in southern Latin America: Brazil.

This survey was conducted in the southern Brazilian state of Rio Grande do Sul and involved 182 farms located in 26 counties. In addition to the three major broad-spectrum anthelmintic groups (viz. benzimidazole, levamisole and ivermectin) the combination benzimidazole and levamisole and the H. contortus specific anthelmintic, closantel, were tested by the faecal egg count reduction method for the prevalence of anthelmintic resistance. Resistance was found to be 90%, 84%, 13%, 73% and 20%, respectively. This is a crisis situation. Immediate, drastic action needs to be implemented, otherwise the sheep industry in this region (approx. 10 million head) will soon face a lack of any effective anthelmintics with the inevitable consequences of major restructuring or abandonment.

Survival and development of ivermectin-resistant or susceptible strains of Haemonchus contortus under field and laboratory conditions.

The free-living development of three strains of Haemonchus contortus was studied in two experiments. Day 21 faecal samples were collected from lambs infected with either a susceptible strain, a laboratory-selected ivermectin (IVM) resistant strain or a South African field strain showing multiple anthelmintic resistance, which included IVM. No eggs hatched in samples cultured at 4 or 10 degrees C. At 22 degrees C the laboratory-selected strain showed the highest rate of development while at 27 degrees C the susceptible strain produced the highest yield of third stage larvae (L3): at both temperatures the field strain showed the lowest percentage development to L3. The second experiment was a field study carried out in southern Brazil. Faeces containing either an IVM-susceptible or an IVM-resistant strain of H contortus were placed in two series of grass plots during each of three summer months. Soil subsequently yielded more larvae than did grass suggesting migration or mechanical transport into the soil. For plots contaminated during the first two months there was no significant difference in recovery rate between the two strains (P > 0.05). When contamination occurred during the third month, the IVM-resistant strain produced significantly higher recovery rates (P < 0.05) from both pasture and soil.

Response to ivermectin treatment of parasitic stages of Haemonchus contortus resistant or susceptible to ivermectin.

Two groups of 33 helminth-naive lambs were infected with 5,000 L3 of an ivermectin-resistant or -susceptible strain of Haemonchus contortus (groups R and S). On days 6, 10, 16, and 21 postinfection, 5 animals from each group were chosen at random and orally treated with 0.2 mg/kg of ivermectin. On each occasion, 2 randomly selected lambs from each group were also killed to determine the number and stage of development of the worms present at the time of treatment. These necropsies revealed that by day 6 early and late fourth-stage larvae were present, whereas on day 10 the early fifth stage had been reached; by days 16 and 21 all worms had reached the adult stage. Necropsies on day 28 postinfection revealed that although animals treated at day 6 had 26.3% fewer worms than the controls, there was no significant difference (P greater than 0.05) between worm burdens from any of the animals infected with the R strain and treated at different times after infection when compared with the untreated controls. With ivermectin significant reductions were obtained in the worm burdens of the animals infected with the susceptible strain; these were reduced by 96% when treatment was given on day 6 against fourth-stage larvae and 98.9% when the drug was given on day 21 against adult stages. From these results it is clear that resistance to ivermectin in this strain of H. contortus is present as early as the fourth larval stage.

[Analysis of fever in 58 cases of infective endocarditis]. / Análise da febre em 58 casos de endocardite infecciosa.

PURPOSE: To evaluate if fever is an objective criterion in the assessment of response to antibiotic therapy and in the prognosis of patients undergoing treatment for infective endocarditis (IE). METHODS: Fifty-eight cases of IE, occurring from January 1980 to December 1989 have been analysed retrospectively in this study. Emphasis was given to the clinical history and body temperature changes during the first five weeks of treatment. Patients were divided in three groups according to the number of febrile peaks per week. Temperature was assessed weekly from each patient's highest peak weighed average. RESULTS: At the first exam, 52 patients (86.2%) presented fever. All patients had at least one episode of fever during their hospitalization. There seemed to be a relation between the number of febrile peaks during a one week period and the mean body temperature, so that these patients who presented four or more peaks in a week had a higher mean body temperature than those with two or less febrile peaks during the week. After the second week of treatment, patients with two or less febrile peaks had a 93.1% survival and average of 35.5 days of hospitalization, whereas those with three or more febrile peaks had 63.6% survival and an average of 47.5 days of hospitalization. CONCLUSION: The results of this study show that the intensity of fever is linked to the number of febrile peaks per week, regardless to treatment duration. Should there be three or more febrile peaks weekly after the second week of treatment, therapeutic strategy should be reviewed, considering even surgical treatment. In many cases, the persistence of fever represented the clinical expression of complications which determined a higher mortality rate and a longer hospitalization.

[Infective endocarditis. Study of 83 cases at the Hospital da Santa Casa de São Paulo]. / Endocardite infecciosa. Estudo de 83 casos no Hospital da Santa Casa de São Paulo.

PURPOSE: To analyse clinical aspects, diagnosis and treatment of infective endocarditis (IE), in order to guide medical procedures and indicate the surgical treatment. PATIENTS AND METHODS: 83 patients were submitted to clinical treatment of IE between January 1980 and December 1987; clinical aspects, laboratory and pathologic-anatomy findings, the site of infection and the entrance of micro-organism were studied. RESULTS: 37 (44.6%) patients were males. Fever was present in 75 (90.4%) cases, cardiac murmur in 76 (91.5%), splenomegaly in 28 (33.7%) and heart failure (III and IV) in 32 (39.8%) patients. Blood culture was positive in 55.5%; staphylococcus 50% of blood cultures; anemia was present in 66 cases (79.5%) and high serum mucoprotein in 58 (92%); echocardiography was 85.7% positive. The mortality was 39.76%; congestive heart failure was the main cause of death; 78.1% of these ones occurred in the first 15 days of antibiotic-therapy. The mitral valve was the one most impaired and the most frequent entrance of micro-organisms in oropharynx. CONCLUSION: Congestive heart failure, sepsis and systemic embolisms were the main complications that led the patient to death in course of IE, usually before 15 days of antibiotic-therapy. In these cases, we may hypothesize that prompt surgical treatment could have diminished the mortality of IE.