Pastoralism in the drylands of Latin America: Argentina, Chile, Mexico and Peru. / Pastoralismo en zonas áridas de Latinoamérica: Argentina, Chile, México y Perú.

This article discusses various aspects of pastoralism in the Latin American countries with the largest dryland areas. The topics covered include: social, economic and institutional issues; grasslands and their carrying capacity; production systems and productivity rates; competition for forage resources between domestic livestock and wildlife; and the health status of livestock and wildlife. Most grasslands exhibit some degree of degradation. The percentage of offspring reaching weaning age is low: 47-66% of calves and 40-80% of lambs. Some pastoralists adopt patterns of transhumance. In the main, pastoralists experience a high poverty rate and have poor access to social services. For many pastoralists, wildlife is a source of food and by-products. Argentina, Chile, Mexico and Peru have animal health control agencies, are members of the World Organisation for Animal Health (OIE) and have signed the United Nations Convention to Combat Desertification. Pastoral systems subsist mainly on income unrelated to pastoral farming. The OIE recognises all four countries as free from infection with peste des petits ruminants virus, and from rinderpest and African horse sickness. It is difficult to predict the future of pastoralism in Latin America because the situation differs from country to country. For instance, pastoralism is more important in Peru than in Argentina, where it is a more marginal activity. In the future, lack of promotion and protection policies could lead to a decline in pastoralism or to an adverse environmental impact on drylands.

Les auteurs abordent les particularités du pastoralisme dans les quatre pays d'Amérique latine dotés des plus vastes étendues de terres arides du souscontinent ; ils examinent notamment les aspects sociaux, économiques et institutionnels du pastoralisme, les pâtures et leur capacité de charge, les systèmes de production et les indices de productivité, la concurrence entre le bétail et les animaux sauvages pour le prélèvement de fourrage et le statut sanitaire respectif des animaux d'élevage et de la faune sauvage. Les prairies dédiées au pastoralisme présentent dans leur majorité un certain degré de dégradation. Le taux de survie au sevrage fluctue entre 47 % et 66 % pour les veaux et entre 40 % et 80 % pour les agneaux. Certains pasteurs adoptent des schémas de transhumance. Les populations pastorales se caractérisent par un niveau élevé de pauvreté et un accès très limité aux services sociaux. Pour de nombreux pasteurs, la faune sauvage constitue une ressource alimentaire directe mais elle fournit aussi des produits dérivés. En Argentine, au Chili, au Mexique et au Pérou, des services gouvernementaux sont chargés du contrôle de la santé animale. Ces pays sont Membres de l'Organisation mondiale de la santé animale (OIE) et signataires de la Convention des Nations Unies sur la lutte contre la désertification. Les systèmes pastoraux subsistent essentiellement grâce à des revenus autres que ceux issus de la production. Ces territoires ont été reconnus par l'OIE comme étant indemnes d'infection par les virus de la peste des petits ruminants, de la peste bovine et de la peste équine. Il est difficile de prédire l'avenir du pastoralisme en Amérique latine, en raison de la diversité des situations rencontrées d'un pays à l'autre. Par exemple, l'activité pastorale est plus importante au Pérou qu'en Argentine où elle a un caractère marginal. L'absence de politiques de promotion et de protection spécifiques pourrait se traduire à l'avenir par un déclin du pastoralisme ou par un impact écologique négatif pour ces zones arides.

Se abordan matices del pastoralismo relativos a los países con mayor extensión de zonas áridas de Latinoamérica, concretamente, los aspectos sociales, económicos e institucionales, los pastizales y su receptividad, los sistemas de producción e índices de productividad, la competencia entre ganado doméstico y fauna silvestre por el recurso forrajero, y el estatus sanitario del ganado y de los animales silvestres. La mayor parte de los pastizales presenta algún grado de deterioro. El porcentaje de crías que llega al destete fluctúa entre el 47% y el 66% en bovinos y entre el 40% y el 80% en ovinos. Algunos pastoralistas adoptan patrones de trashumancia. Los pastores se caracterizan básicamente por un índice alto de pobreza y un escaso acceso a los servicios sociales. La fauna es un recurso alimentario y una fuente de subproductos para numerosos pastores. Argentina, Chile, México y Perú cuentan con organismos destinados al control de la sanidad animal, son miembros de la OIE y han suscrito la Convención de las Naciones Unidas de Lucha contra la Desertificación. Los sistemas pastoriles subsisten principalmente a partir de ingresos ajenos a su producción. La OIE reconoce a estos territorios como libres de infección por peste de los pequeños rumiantes, por peste bovina y por peste equina. Es difícil predecir el futuro del pastoralismo en Latinoamérica debido a las diferentes situaciones de cada país. Así, por ejemplo, en Perú, esta práctica tiene mayor importancia que en Argentina, donde es más marginal. La carencia de políticas de promoción y protección podría conducir en el futuro a una disminución de la actividad o a un impacto ecológico negativo en las zonas áridas.

Biochemical and haematological measurements in beef cattle in Mendoza plain rangelands (Argentina).

Biochemical and haematological measurements were used to identify constraints on productivity in beef cattle. One hundred and twelve Aberdeen Angus and Criollo Argentino females including lactating cows, dry non-pregnant cows and heifers were selected. Blood samples were taken in the middle of summer and autumn. Serum was analysed for haemoglobin, PCV, glucose, albumin, urea, creatinine, Ca, P, Mg, Fe, Cu, ALP, AST, ALT, CK, LDH, Cl-, Na and K content. Globulin was calculated by taking the difference between total protein and albumin. Percentages of all cattle that had metabolite levels outside reference ranges were: 15% (glucose), 8% (globulin), 5% (urea), 96% (Ca), 50% (P), 12% (Mg), 20% (Na), 5% (K), 24% (Cl), 18% (Fe), 5% (Cu) and 85% (CK). These results indicate with some certainty that dietary protein was not limiting. Body condition score loss was detected only in lactating cows. There were a few animals that could have presented chronic inflammatory disease. Phosphorus could be an important potential constraint on fertility, although the presence of symptoms of hypophosphataemia was not observed. The study also demonstrates the absence of anaemia or liver disease. Breed, seasonal and physiological state differences in some blood metabolites could be attributed to one or more of the following factors: chemical composition of the feed ingested, environmental temperature, nutrient content of the forage, animal age and cattle foraging experience. The study provides a basis for implementing helpful adjustments in current cattle management practices so as to alleviate the constraints on productivity, provided that these practices are profitable.

Ceftriaxone compared with doxycycline for the treatment of acute disseminated Lyme disease.

BACKGROUND: Localized Lyme disease, manifested by erythema migrans, is usually treated with oral doxycycline or amoxicillin. Whether acute disseminated Borrelia burgdorferi infection should be treated differently from localized infection is unknown. METHODS: We conducted a prospective, open-label, randomized, multicenter study comparing parenteral ceftriaxone (2 g once daily for 14 days) with oral doxycycline (100 mg twice daily for 21 days) in patients with acute disseminated B. burgdorferi infection but without meningitis. The erythema migrans skin lesion was required for study entry, and disseminated disease had to be indicated by either multiple erythema migrans lesions or objective evidence of organ involvement. RESULTS: Of 140 patients enrolled, 133 had multiple erythema migrans lesions. Both treatments were highly effective. Rates of clinical cure at the last evaluation were similar among the patients treated with ceftriaxone (85 percent) and those treated with doxycycline (88 percent); treatment was considered to have failed in only one patient in each group. Among patients whose infections were cured, 18 of 67 patients in the ceftriaxone group (27 percent) reported one or more residual symptoms at the last follow-up visit, as did 10 of 71 patients in the doxycycline group (14 percent, P > or = 0.05). Mild arthralgia was the most common persistent symptom. Both regimens were well tolerated; only four patients (6 percent) in each group withdrew because of adverse events. CONCLUSIONS: In patients with acute disseminated Lyme disease but without meningitis, oral doxycycline and parenterally administered ceftriaxone were equally effective in preventing the late manifestations of disease.

Azithromycin compared with amoxicillin in the treatment of erythema migrans. A double-blind, randomized, controlled trial.

OBJECTIVE: To determine whether azithromycin or amoxicillin is more efficacious for the treatment of erythema migrans skin lesions, which are characteristic of Lyme disease. DESIGN: Randomized, double-blind, double-dummy, multicenter study. Acute manifestations and sequelae were assessed using a standardized format. Baseline clinical characteristics and response were correlated with serologic results. Patients were followed for 180 days. SETTING: 12 outpatient centers in eight states. PATIENTS: 246 adult patients with erythema migrans lesions at least 5 cm in diameter were enrolled and were stratified by the presence of flu-like symptoms (such as fever, chills, headache, malaise, fatigue, arthralgias, and myalgias) before randomization. INTERVENTION: Oral treatment with either amoxicillin, 500 mg three times daily for 20 days, or azithromycin, 500 mg once daily for 7 days. Patients who received azithromycin also received a dummy placebo so that the dosing schedules were identical. RESULTS: Of 217 evaluable patients, those treated with amoxicillin were significantly more likely than those treated with azithromycin to achieve complete resolution of disease at day 20, the end of therapy (88% compared with 76%; P=0.024). More azithromycin recipients (16%) than amoxicillin recipients (4%) had relapse (P=0.005). A partial response at day 20 was highly predictive of relapse (27% of partial responders had relapse compared with 6% of complete responders; P<0.001). For patients treated with azithromycin, development of an antibody response increased the possibility of achieving a complete response (81% of seropositive patients achieved a complete response compared with 60% of seronegative patients; P=0.043). Patients with multiple erythema migrans lesions were more likely than patients with single erythema migrans lesions (P<0.001) to have a positive antibody titer at baseline (63% compared with 17% for IgM; 39% compared with 16% for IgG). Fifty-seven percent of patients who had relapse were seronegative at the time of relapse. CONCLUSIONS: A 20-day course of amoxicillin was found to be an effective regimen for erythema migrans. Most patients were seronegative for Borrelia burgdorferi at the time of presentation with erythema migrans (65%) and at the time of relapse (57%).

Clarithromycin in treatment of early Lyme disease: a pilot study.

Forty-one patients with erythema migrans were enrolled in an open-labelled pilot study of oral clarithromycin, 500 mg twice daily for 21 days, for the treatment of early Lyme disease. Immediately posttherapy, pretreatment signs and symptoms resolved among 91% of the 33 evaluable patients. At 6 months, all 28 of the evaluable patients were well. Clarithromycin shows promise as an effective agent for the treatment of early Lyme disease and warrants further study.

Comparison of cefuroxime axetil and doxycycline in treatment of patients with early Lyme disease associated with erythema migrans.

A randomized, multicenter, investigator-blinded clinical trial was undertaken in order to compare the efficacies of cefuroxime axetil and doxycycline in the treatment of patients with Lyme disease associated with erythema migrans. A total of 232 patients with physician-documented erythema migrans were treated orally for 20 days with either cefuroxime axetil, 500 mg twice daily (119 patients), or doxycycline, 100 mg three times daily (113 patients), and clinical evaluations were conducted during treatment (8 to 12 days) and at 1 to 5 days and 1, 3, 6, 9, and 12 months posttreatment. Patients were assessed as to the resolution of erythema migrans and of the signs and symptoms related to early Lyme disease as well as to the prevention of late Lyme disease. A satisfactory clinical outcome (success or improvement) was achieved in 90 of 100 (90%) evaluable patients treated with cefuroxime axetil and in 89 of 94 (95%) patients treated with doxycycline (difference, -5%; 95% confidence interval, -12 to 3%). Patients with paresthesia, arthralgia, or irritability at enrollment were at higher risk for an unsatisfactory clinical outcome at 1 month posttreatment. Of the patients with satisfactory outcomes at 1 month posttreatment who were evaluable at 1 year posttreatment, a satisfactory outcome was achieved in 62 of 65 (95%) and in 53 of 53 (100%) patients treated with cefuroxime axetil and doxycycline, respectively (difference, -5%; 95% confidence interval, -10 to 4%). Twenty-eight percent of patients treated with doxycycline and 17% of those treated with cefuroxime axetil had one or more drug-related adverse events (P = 0.041). Doxycycline was associated with more photosensitivity reactions (6% compared with 0% for patients treated with cefuroxime axetil; P=0.006), and cefuroxime axetil was associated with more cases of diarrhea (5% compared with 0% for patients treated with doxycycline; P=0.030). Jarisch-Herxheimer reactions occurred in 12% of the patients in each treatment group. In summary, cefuroxime axetil is well tolerated and appears to be equally as effective as doxycycline in the treatment of early Lyme disease and in preventing the subsequent development of late Lyme disease.

Serological evidence for simultaneous occurrences of Lyme disease and babesiosis.

Babesia microti and Borrelia burgdorferi, the spirochetal agent of Lyme disease, are both transmitted by the tick Ixodes dammini. Serological evidence has shown that 54% of the patients with babesiosis tested have IgG and IgM antibodies to the spirochete causing Lyme disease. Likewise, 66% of randomly selected patients with Lyme disease from geographic areas endemic for both diseases, but not from areas where babesiosis does not occur, also have IgM and IgG antibodies to B. microti. Antigenic cross-reactivity is not the reason for these findings, as laboratory animals experimentally infected with B. microti do not develop antibodies to B. burgdorferi, and laboratory animals immunized with organisms derived from pure cultures of spirochetes do not develop antibodies to B. microti. We suggest that these patients are concurrently exposed to both organisms by doubly infected tick vectors.

Antibodies of patients with Lyme disease to components of the Ixodes dammini spirochete.

Lyme disease is an inflammatory disorder of skin, joints, nervous system, and heart. The disease is associated with a preceding tick bite and is ameliorated by penicillin treatment. A spirochete (IDS) isolated from Ixodes dammini ticks has been implicated as the etiologic agent of Lyme disease. We examined the antibody responses of Lyme disease patients to IDS lysate components in order to further understand the pathogenesis of this disease. The components were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred to nitrocellulose, reacted with patients' sera, and the bound IgG was detected with 125I-labeled protein A (western blot). We found that (a) Lyme disease patients had antibodies to IDS components (b) most patients studied had antibodies to two components with apparent subunit molecular weights of 41,000 and 60,000, and (c) the patients' antibody responses during illness and remission were specific, for the most part, for the IDS. In contrast to the findings with Lyme disease sera, sera from controls showed little reactivity with IDS components in either the western blots or a derivative solid-phase radioimmunoassay.

Human babesiosis. Clinical and therapeutic considerations.

During a two-month period, six patients from eastern Long Island were identified as having Babesia microti infection. Diagnosis was based on characteristic blood smears, hamster inoculation, or both. Symptom duration ranged from 19 to 24 days in five patients. The sixth patient, who had previously undergone splenectomy, had a more severe and prolonged illness. No specific therapy was administered to five patients. The patient who had had a splenectomy was treated with chloroquine, quinine, pentamidine, and exchange transfusions. There were no deaths. It appears that most cases of human B microti infection can be effectively managed with symptomatic and supportive care.

Lyme disease-a tick-borne spirochetosis?

A treponema-like spirochete was detected in and isolated from adult Ixodes dammini, the incriminated tick vector of Lyme disease. Causally related to the spirochetes may be long-lasting cutaneous lesions that appeared on New Zealand White rabbits 10 to 12 weeks after infected ticks fed on them. Samples of serum from patients with Lyme disease were shown by indirect immunofluorescence to contain antibodies to this agent. It is suggested that the newly discovered spirochete is involved in the etiology of Lyme disease.

Ketoprofen in the treatment of rheumatoid arthritis. Double-blind, cross-over placebo comparison.

In a two week double-blind cross-over trial of ketoprofen versus placebo in twelve patients, ketoprofen was shown to have substantial anti-inflammatory activity and to be more effective than placebo. Clinical and biological tolerance were excellent.