Impact on beef cattle productivity of infection with anthelmintic-resistant nematodes.

ABSTRACTAims: The main goal of the current study was to evaluate, on a commercial beef cattle farm, the impact of infection with gastrointestinal nematodes resistant to both ivermectin (IVM) and moxidectin (MXD) on the productivity of calves.Methods: Male Aberdeen Angus calves, aged 9-11 months, with faecal nematode egg counts (FEC) ≥200 epg and body weight ≥190 kg, were allocated to two herds. Herd A (n = 90) grazed a maize-winter forage crop rotation and Herd B (n = 90) grazed a 2-year-old Agropyrum pasture. On Day 0 in each herd, calves were randomly allocated into five groups (n = 18), which were treated with 0.2 mg/kg IVM; 0.2 mg/kg MXD; 3.75 mg/kg ricobendazole (RBZ), both IVM and RBZ, or remained untreated. Faecal samples collected on Days -1 and 19 were used to determine the percentage reduction in FEC, and genera of the nematodes were determined by the identification of the third-stage larvae recovered from faecal cultures. Total weight gain was determined from body weights recorded on Days -1 and 91.Results: Overall mean reduction in FEC was 42% for IVM, 67% for MXD, 97% for RBZ and 99% for IVM + RBZ. The reduction in FEC for Cooperia spp. was ≤78% for IVM and MXD, and for Haemonchus spp. was 0 and 36% for IVM and MXD, respectively, confirming the presence of parasites resistant to both anthelmintics. Only IVM + RBZ treatment resulted in 100% efficacy against Haemonchus spp. The overall estimated mean total weight gain for calves treated with IVM was 15.7 (95% CI = 11.9-19.7) kg and for calves treated with IVM + RBZ was 28.8 (95% CI = 25-32.5) kg (p < 0.001). Mean total weight gain for calves treated with MXD was 23.5 (95% CI = 19.7-27.2) kg.Conclusions and clinical relevance: In calves naturally infected with resistant nematodes, under the production system assessed here, weight gains were lower in calves treated with anthelmintics that were moderately or highly ineffective compared to those treated with highly effective anthelmintics. These results demonstrate to farmers and veterinarians the importance of a sustainable and effective nematode control under field conditions.

Effect of gastrointestinal nematodes on serum copper and phosphorus of growing beef calves in northwestern Argentina.

The aim of this work was to study the effect of gastrointestinal nematodes (GINs) on copper (Cu) and phosphorus (P) in blood of beef cattle in two ranches (R1 and R2) located in northwestern Argentina. In 2015-2016 (R1) and 2016-2017 (R2), in each ranch, 22 weaned female calves were divided into two groups: calves treated systematically with 200 mcg/kg moxidectin every 45-50 days (TG) and untreated calves (UTG). The following parameters were measured: number of fecal eggs (epg), fecal cultures, serum Cu and P levels, and live weight gain (LWG). Differences between groups were compared using analysis of variance and Tukey test. GIN infections in both ranches were subclinical and moderate, showing the highest epg (R1 = 907 ± 754; R2 = 1049 ± 1040) by mid-winter. Epg values of TG groups were always negligible (> 93% of moxidectin efficacy). The dominant nematode genera were Cooperia and Haemonchus. The average serum Cu values (µg/dl) indicated low (R1 = 49.7 ± 18) and severe (R2 = 27.2 ± 14) deficiency. The effect of treatments was evident in both ranches from late winter, with TG showing significantly (p < 0.01) higher serum levels in winter, spring, and early autumn (R1 = 65.1, 50.9, and 60.3; R2 = 48.0, 25.7, and 22.4) than UTG (R1 = 44.3, 33.9, and 32.9; R2 = 25.5, 18.2, and 16.4). There were no differences in serum P levels between groups. LWG of TG increased significantly (p < 0.008) (27.2% in R1 and 38.6% in R2), with respect to those of UTG. This study showed a negative effect of GIN on serum Cu values in moderately infected growing calves.

The effect of gastrointestinal nematode infection level on grazing distance from dung.

Avoiding grazing near feces is an efficient strategy to prevent parasitic infection and contamination; therefore, in the evolution of herbivorous species, this behavior may have developed as a mechanism to protect the host against infection by gastrointestinal nematodes. The aim of this study was to assess whether grazing distance from dung is related to the level of parasitic infection in cattle. Based on Fecal Egg Count (FEC) means, 18 castrated male steers, aged 18 months, were divided into three groups: High (FEC ≥ 315); Medium (FEC = 130-160); and Low (FEC = 40-70). To analyze the response to a new natural infection by gastrointestinal nematodes and to standardize infection levels, all animals received anthelmintic treatment at twenty days prior to field observation. Three observers simultaneously collected data on grazing behavior for 2.5 hours/week for 12 weeks. Observers recorded the distance when grazing occurred at less than one meter from dung. Every two weeks, fecal samples were collected for FEC, as well as serum samples to measure immunoglobulin G (IgG) levels against larvae and adult antigens of the parasitic species Haemonchus placei. All groups grazed farther from the dung on days of greater insolation (r = 0.62; P = 0.03). Animals with high levels of parasitism grazed farther from the dung (P < 0.05) but had lower levels (P < 0.0001) of IgG serum levels compared to those with medium and low levels of infection. FEC values varied over the experiment, remaining below 200 for the low and medium group and reaching 1000 (P < 0.01) for the animals with the highest rates of parasitism. Our results indicate that cattle showing high levels of parasitism are more likely to avoid contaminated areas than animals with lower infection levels, and the immune system seems to be involved in such behavior.

Clinical features of 121 patients with diffuse unilateral subacute neuroretinitis.

PURPOSE: To describe the determinant clinical signs to diagnose diffuse unilateral subacute neuroretinitis (DUSN) and the main features related to identification of the live worm. DESIGN: Retrospective study performed at the Federal University of Rio Grande do Norte, Rio Grande do Norte, Brazil, between 2003 and 2008. METHODS: Patients with early- or late-stage diffuse unilateral subacute neuroretinitis were included. All patients underwent complete ophthalmologic examination and had a minimum of 6 months of follow-up. RESULTS: A total of 121 patients were included. Most patients were younger than 20 years (69.42%). Visual acuity was 20/400 or worse in 86 patients (71.7%). Nine patients (7.43%) presented in the early stage and 112 (92.57%) patients presented in the late stage. Subretinal tracks (91.7%), focal alterations of the retinal pigment epithelium (89.3%), small white spots (80.2%), and optic nerve atrophy (76.9%) were the most frequent clinical features. The subretinal worm was identified in 48 patients (39.66%), and laser treatment to destroy it was performed in all cases. The most common location of the nematode was the posterior pole (21 patients). It was observed that the younger the age, the higher the indices of larvae identification (P=.022). Multifocal yellow-white lesions and vitritis were correlated with identification of the worm (P=.001). Mean logarithm of the minimal angle of resolution visual acuity was 1.466 (20/600) and 1.281 (20/400) before and after laser treatment, respectively (P<.005). CONCLUSIONS: Identification of clinical signs and diagnosis of diffuse unilateral subacute neuroretinitis in its early stage, followed by prompt location and destruction of the worm by photocoagulation, may improve the vision of affected patients.

Epidemiology and effects of gastrointestinal nematode infection on milk productions of dairy ewes.

66 Pampinta breed ewes were studied during milking to evaluate the infection and the effect of gastrointestinal nematode on milk production sheep system. Naturally infected ewes on pasture were randomly allocated to two groups: TG, suppressively treated group every four weeks with levamisole and UG, untreated group. Faecal nematode egg counts and larval differentiation were conducted monthly. Successive groups of worm free tracer lambs were grazed with ewes and then slaughtered for worm counts. Test-day milk yield of individual ewes was recorded and ewe machine-milking period length (MPL) were estimated. Faecal egg counts and tracer nematode numbers increased towards midsummer and declined sharply toward the end of the study. TG (188.0 +/- 60 liters) produced more (p < 0.066) milk liters than UG (171.9 +/- 52.2) and TG had significantly more extended (p < 0.041) MPL than those of UG. The present study showed that dairy sheep were negatively affected by worms, even when exposed to short periods of high acute nematode (mainly Haemonchus contortus) infection.

Early-stage diffuse unilateral subacute neuroretinitis: improvement of vision after photocoagulation of the worm.

PURPOSE: To evaluate the visual outcome after direct laser photocoagulation of the worm in patients with early-stage diffuse unilateral subacute neuroretinitis (DUSN). METHODS: We report on four patients with DUSN diagnosed in its early stage, in whom the worm was identified and destroyed by laser photocoagulation. RESULTS: In all the four cases, resolution of the inflammatory multifocal lesions was achieved within 1 month of treatment. After that period and during follow-up (mean 11.5 months), visual acuity improved in three eyes and remained unchanged in one eye. CONCLUSION: The diagnosis of DUSN in its early stage followed by prompt location and destruction of the worm by photocoagulation may improve vision of affected patients.

Lagoquilascaríase com invasäo de coluna cervical / Lagoquilascariase with cervical column invasion

Introdução: Doença rara causada por um nematódio parasita de tecidos - Lagochilascaris minor - que possui tropismo por músculos ou partes moles da região cervical, onde provoca lesões tumorais que podem se fistulizar ou ulcerar, com saída de material seropurulento e vermes. O mecanismo de infecção ainda não esta esclarecido, mas a hipótese mais aceita atualmente é a de Smith - infecção por ingestão de larvas encistadas nos músculos e outros tecidos de animais silvestres. As larvas de terceiro estádio que se libertam dos cistos em nível de estômago do hospedeiro definitivo, por um tropismo qualquer ainda não esclarecido, migram esôfago acima, rumo às áreas comumente afetadas do pescoço e circunvizinhanças. Objetivo: Com a descrição do caso, tornar conhecida essa helmintíase de maior prevalência na Região Norte e difícil controle clínico que causa constrangimento do paciente para o convívio social, levando ao abandono do tratamento ao primeiro sinal de melhora (desaparecimento da tumoração com freqüente recidiva). Relato do caso: M.C.S., 19 anos, sexo feminino, procedente de Entre Rios, sul do Estado de Roraima - Amazônia - Brasil, parda, com costume de ingerir carne de caça, principalmente para. Internada dia 04/11/97 com quadro de tumoração cervicomastóidea esquerda, com fístula cutânea e drenagem de material serocaseoso e eliminação de vermes filiformes, bem estado geral, lúcida e orientada, normocorada, dor cervical, eliminação (principalmente flexão lateral), sem déficit neurológico. Ausência de febre e perda ponderal; ausculta pulmonar e cardíaca e exame de abdome dentro da normalidade. A tomografia computadorizada de base de crânio e coluna cervical mostrou massa cervical à esquerda, multinodulada, com áreas internas de densidade de líquido e erosão do osso eccipital e primeira vértebra cervical

Ecology of the free living stages of cattle nematodes during summer contamination in Argentina Western Pampas.

Development, migration and survival of infective larvae (L3) were studied in the Western Pampeana Region. Faeces of naturally nematode infected cattle were deposited as artificial pats on plots during mid-spring-summer of 1994/1995 and 1995/1996. Since the start and during 1995, the study coincided with a severe drought, rainfalls being 29% below the 45-year means. The predominant genera recovered were Cooperia, Ostertagia and Haemonchus. Initial and peak recovery of L3 from pats occurred 8-15 and 15-21 days later respectively. A low percentage of L3 survived from November (0.3% L3) and January (0.06% L3) to the following autumn and winter. The mean persistence of larvae detected in pats or herbage was around 200 days from deposition. The migration of L3 from faecal pats to herbage started 15 to 30 days after deposition according to rainfall occurrence. Maximum herbage recoveries of L3 from pats deposited in late summer occur during autumn rainfalls. Only, few L3 were occasionally recovered from soil. Summer conditions were associated with rapid development and translation of L3 to herbage, but also with low L3 detection after initial recoveries. Faecal pats deposited from mid-summer were the main source of autumn herbage contamination.

Eosofilia elevada como manifesticiones viscerales: VI. Infección por larva de nemátodo de 427 µ / High eosinophilia with visceral manifestations: VI. Nematode's larva infection of 427 µ

Se discute el estado actual del conocimiento sobre los cuadros clínicos de eosinofilia por helmintiasis parenteral, quedando aquí englobados los síndromes de Löeffler, eosinofilia tropical, granulomatosis larvaria, endoftalmitis por nemátodos y de Friess-Pierrou. Se revisan los posibles diagnósticos etiológicos en estos pacientes. Se presenta el caso de una niña de 18 meses de edad con gran eosinofilia y hepatomegalia, en la que se encontró una larva de 427 µ de largo en el hígado. Se determinó que la larva no corresponde a un parásito habitual del hombre ni a parasitos de animales que ya se hayan encontrado en el hombre. Se opinó que tal larva puede ser un nemátodo parásito de plantas o de insectos, o quizá del género Logibucca, parásito de serpientes y murciélagos. Sea cual sea su posición taxonómica, agranda enormemente las posibilidades etiológicas del síndrome aquí estudiado

First case of Lagochilascaris minor infection in Bolivia.

Few cases of human infection with Lagochilascaris minor have been reported in the literature. They occurred in Central and South America and the Caribbean. We describe the first patient with this nematode infection in Bolivia.

Nippostrongylus brasiliensis: physiological and metabolic responses of rats to primary infection.

Primary infection of rats with Nippostrongylus brasiliensis was associated with alterations in host protein, carbohydrate and lipid metabolism. Infected rats fed ad libitum were compared with uninfected, weight matched, pair fed rats. Metabolic changes detected were related to the level of infection (larvae/g body weight) and also the time course of development of the parasite. The intestinal stage of the infection was associated with marked catabolism of skeletal muscle which did not appear to be mediated by increased secretion of corticosteroids. Plasma concentrations of protein in infected rats were altered even at the lowest dose (27 l/g), and in a biphasic manner corresponding to larval and adult stages of the parasite. Plasma globulin concentrations were increased on Day 2 after infection while from Days 5-10 after infection, plasma concentrations of both globulin and albumin were much reduced. Hypoglycemia developed on Days 8-9 after infection in rats given a dose of greater than or equal to 39 l/g. Infected rats had increased plasma concentrations of non-esterified fatty acids and in marked contrast with their pair fed partners, plasma triglyceride concentration increased dramatically with both the dose of parasites given and the duration of infection. The responses of the rat to infection with N. brasiliensis are compared with host responses to other helminths and microorganisms, and suggestions are made as to their possible functions and significance.

Neonatal IgE injections do not modify Nippostrongylus brasiliensis-induced and mercuric chloride-induced IgE increase in the rat.

The effect of neonatal IgE injections on total IgE responses was studied in two rat models. After Nippostrongylus brasiliensis infection, no differences in serum IgE level and surface or cytoplasmic IgE expression were observed between IgE-treated and control LOU/C rats. Likewise, after HgCl2 injection, IgE-treated Brown-Norway rats and controls showed no difference in serum IgE level or in the development of autoimmune glomerulonephritis and proteinuria. It has been concluded that IgE-class-restricted tolerance, induced by neonatal injections of IgE, cannot be observed in rats after strong IgE stimulation.

Physiological responses of rats to primary infection with Nippostrongylus brasiliensis.

The physiological responses of well-nourished rats to primary infection with the intestinal nematode Nippostrongylus brasiliensis were examined. Infected rats fed ad libitum were compared with uninfected control rats fed ad lib. and with uninfected rats which were pair-fed to the infected rats. Following infection with N. brasiliensis rat food intake was reduced from day 2 post infection (pi) and there were two periods of minimal food intake (days 2 to 3 and 8 to 9 pi). The water intake of infected rats was only reduced on days 2, 3 and 9 pi and not to the same extent as food intake. Muscle catabolism in infected rats was more severe than could be explained on the basis of their food intake reduction. The rectal temperature and rate of oxygen consumption per g body-weight of rats was not significantly altered by the infection. Host responses to N. brasiliensis are compared with those seen in microbial infections and some of them are found to be considerably different.

Endocrine responses of protein-malnourished rats infected with Nippostrongylus brasiliensis (Nematoda).

During the course of a primary infection of Nippostrongylus brasiliensis in protein-malnourished rats, plasma concentrations of corticosterone were found to decrease from 0.89 +/- 0.03 at the start of the infection to 0.28 +/- 0.08 mumol/l, 9 days post-infection (p.i.). Similarly, adreno-corticotrophic hormone levels were also observed to fall from 62.09 +/- 12.06 to 20.54 +/- 1.81 by 5 days p.i. and to 35.12 +/- 16.61 nmol/l by 9 days p.i. However, no significant changes were seen in the dry weight of the adrenal glands other than those expected in relation to changes in body weight. Concentrations of both plasma tri-iodothyronine and thyroxine were also severely depleted over the same period from 5.33 +/- 0.34 to 1.09 +/- 0.42 and 104.43 +/- 10.4 to 34.12 +/- 8.95 nmol/l respectively. This was considered not to be due to any change in the capacity of the plasma to bind these hormones. Results for insulin were highly variable, but overall were lower from protein-malnourished rats than results documented for well-nourished rats and a reduction from 18.07 +/- 3.17 to 6.08 +/- 2.18 mu units/ml, 9 days p.i. was observed. The results are discussed in relation to the role of these hormones in protein metabolism in a protein-malnourished animal.

Dose-dependent relationships between Nippostrongylus brasiliensis populations and rat food intake.

The pattern of daily food intake of well-nourished rats infected with Nippostrongylus brasiliensis included 2 distinct phases when food intake was much less than that of uninfected controls (days 0-4 and days 6-10 p.i.). These phases were separated by a period (days 4-6) of still reduced but relatively constant food intake. From day 10 p.i. food intake increased so that between days 12 and 17 infected rats ate more than uninfected controls. In each of the phases of reduced food intake there was a threshold dose above which food intake was further decreased as dose increased. In contrast to the obvious relationship between food intake and dose, food intake could not easily be related to the size of the adult Nippostrongylus population, as judged by egg and worm counts. The relationship appears to be complicated by host variability in susceptibility to infection and to the pathological effects of infection. Effects of N. brasiliensis on the daily pattern of food intake can be explained with respect to stages in the development of the parasite and host responses directed against the adult worms.

Impact of Nippostrongylus brasiliensis (Nematoda) on the serum albumin and amino acid concentrations of rats fed adequate or protein-deficient diets.

Food intake, body weight changes, serum protein and amino acid concentrations were measured during the course of primary infections of Nippostrongylus brasiliensis in rats fed on either a 2% protein (casein) diet or a 16% protein diet (Oxoid 41 B). Total serum protein concentration declined from 77.84 +/- 5.35 mg/ml in uninfected well-nourished rats to 54 +/- 3.29 mg/ml in rats at 9 days post-infection (p.i.). A reduction from 47.80 +/- 2.78 to 40.38 +/- 5.62 mg/ml had occurred in protein-malnourished rats by day 6 p.i. The hypoproteinaemia was accompanied by significant hypoalbuminaemia in the protein-malnourished rats and concentrations fell from approximately 33 to 19 mg/ml at the time of peak infection. Six days after inoculation, a significant increase was detected in the concentration of serum amino acids in both well-nourished and protein-malnourished rats; the effect was more prolonged for non-essential than for essential amino acids. The results are discussed briefly in relation to recent work on the control of protein metabolism during malnutrition.

Behavior of single- and mixed-sex infections of Nippostrongylus brasiliensis in fed and fasted mice.

The behavior of male and female Nippostrongylus brasiliensis differed in the intestines of mice. Intraintestinal insertion of female worms at sites that represented 5 or 20% of the pyloric-caecal distance revealed localization at those sites, whereas male populations dispersed over 50% of the intestinal length. However, introduction of females at 40% of the intestine showed a wider distribution that was similar to the male's behavior at all three locations in the intestine. Insertions of both sexes reduced the male's dispersal behavior and arrested the female's preferential localization at the 5 and 20% intestinal sites. Females that were posterior in the intestine showed no dose-dependent movement toward males that were more anterior over various distances or with various combinations of ages of males and females. Food deprivation altered the behavior of females, but this change was inhibited, apparently by males, in bisexual groups. Dispersal of bisexual populations in the intestine was independent of helminth density after fasting of the host.