Use of pathophysiological indicators for individual decision of anthelmintic treatment of ewes against gastro-intestinal nematodes in Morocco.

The targeted selective treatments (TST) aim at reducing the number of anthelmintic treatments but also to maintain productivity of animals. The aim of this work was to assess the validity of pathophysiological indicators for detecting individually ewes in need for treatments in two regions of Morocco with different management and climatic environment (Chaouia plain-seven farms, and Middle-Atlas-three farms). Although resistance to benzimidazoles was already present the same drug was used for TST. The indicators tested were: FAMACHA(©) (associated with anaemia), DISCO (diarrhoea score), and BODCON (body condition score). Only FAMACHA(©) and DISCO indicators were well correlated to the EPGs. DISCO only did permit a substantial reduction (up to 85%) of the number of treatment and EPG (nematode eggs per gramme) remained low on average (less than 160).

A survey on meat sheep farms in two regions of Morocco on farm structure and the acceptability of the targeted selective treatment approach to worm control.

Sheep production is very important in Morocco and two regions (Chaouia plain and semi-mountainous Middle-Atlas) play a significant role in this production. Ten farms were investigated for nematode species and resistance each region. Pooled material from each region provided evidence of benzimidazole resistance in Teladorsagia in both regions; Haemonchus contortus was resistant in the Chaouia only. Forty eight farms in Chaouia and 27 farms in Middle-Atlas were given questionnaires in order to characterize farms and sheep production and to investigate interest in anthelmintic targeted selective treatments (TST) against digestive-tract strongyles. TST is intended to restrict the use of anthelmintics to animals with high infection or presenting clinical signs. The acceptance of TST (67 and 81% of farmers at Chaouia plain and Middle-Atlas respectively) was strongly associated with availability of guidance for infection or clinical markers for selecting sheep in need of treatment. TST interest is associated with health indicators (Gower coefficient nearly one) and the lower cost of TST is highly attractive. The farmers showing an interest in TST have a larger number of ewes, use pasture under forest and have higher number of lambs consumed or sold per ewe. They tend to have collective ownership, acceptable hygienic conditions in the sheepfold and contracted workers. They turn to their neighbours regarding sick animals and get advice on drug selection from veterinarians. The structure of the farm is then linked to the potential use of TST.

The role of targeted selective treatments in the development of refugia-based approaches to the control of gastrointestinal nematodes of small ruminants.

Anthelmintic resistance is recognised as a major problem affecting small ruminant production worldwide and now threatens the sustainability of many of these systems. One method that has been proposed to prolong the efficacy of our current anthelmintics is the maintenance of a parasite population in refugia (unexposed to a drug) which will maintain the genes for susceptibility within the parasite population. Management strategies that employ refugia-based methods include targeted or strategically timed whole flock treatments, targeted selective treatments (TST), whereby only a proportion of the flock is treated at any one time, and the dilution of resistant with susceptible parasites. The ability to effectively target anthelmintic use relies on the identification of those animals that will most benefit from treatment. This review explains the concept of refugia, describes the role of refugia-based approaches to the management of anthelmintic resistance and reviews the markers that have been studied as indicators for TSTs as well as the implementation of refugia-based strategies. Recent results suggest that targeting anthelmintic treatment on the basis of anaemia, milk production and liveweight gain may offer a means of reducing anthelmintic usage whilst still maintaining animal performance.

Poor efficacy of the most commonly used anthelmintics in sport horse nematodes in Morocco in relation to resistance.

Sport and leisure horses in Morocco are treated with several anthelmintics, organophosphates (dichlorvos), benzimidazoles (mostly thiabendazole) or tetrahydropyrimidines (mostly pyrantel pamoate) against nematodes. We studied three horse stables in Rabat, one in Meknes and one in Bouznika. Two of the Rabat and Bouznika stables had introduced a large number of horses from countries (Argentina or Europe) where resistance to benzimidazoles is frequent, whereas the Meknes stud farm remained without foreign introduction. The number of treatments was not very frequent (twice a year in adult horses) but the same anthelmintics were used repeatedly. No resistance to dichlorvos was detected whereas benzimidazole and pyrantel pamoate resistances were detected for the first time in African horses, outside South Africa.

Faecal egg count reduction test for assessing anthelmintic efficacy: average versus individually based estimations.

The faecal egg count reduction (FECR) in faeces is the most widely used method to assess the efficacy of anthelmintics against gastrointestinal strongyles. Several methods are used and they yield different efficacy values. They give important weight to those animals which excrete the majority of eggs, before or after treatment. We propose using individual animal FECR tests that give equal weight to every tested host. The first method is based on a before and after treatment without untreated controls, whereas the second one takes into account the use of non-treated control hosts. Confidence interval at P = 0.95 were established on bootstrap resamples for both individual-based methods. The individual-based FECR presented lower values than the average-based FECR in most cases. The individual FECR provided reliable evaluation when egg counts were over 300 eggs/g and when at least 10 animals were tested.

A comparative kinetic study of ivermectin and moxidectin in lactating camels (Camelus dromedarius).

The plasma and milk kinetics of ivermectin (IVM) and moxidectin (MXD) was evaluated in lactating camels treated subcutaneously (0.2 mg kg(-1)) with commercially available formulations for cattle. Blood and milk samples were taken concurrently at predetermined times from 12 h up to 60 days post-administration. No differences were observed between plasma and milk kinetics of IVM, while substantial differences were noted between plasma and milk profiles of MXD in that both the maximal concentration (Cmax) and the area under concentrations curves (AUC) were three to four-fold higher for milk than for plasma. The time (Tmax) to reach Cmax was significantly faster for MXD (1.0 day) than that for IVM (12.33 days). The Cmax and the AUC were significantly higher for MXD (Cmax = 8.33 ng ml(-1); AUC = 70.63 ng day ml(-1)) than for IVM (Cmax = 1.79 ng ml(-1); AUC = 30.12 ng day ml(-1)) respectively. Drug appearance in milk was also more rapid for MXD (Tmax = 3.66 days) compared to IVM (Tmax = 17.33 days). The extent of drug exchange from blood to milk, expressed by the AUCmilk/AUCplasma ratio, was more than three-fold greater for MXD (4.10) compared to that of IVM (1.26), which is consistent with the more lipophilic characteristic of MXD. However, the mean residence time (MRT) was similar in both plasma and milk for each drug.

Immune response against Leishmania antigens in dogs naturally and experimentally infected with Leishmania infantum.

Cell-mediated and humoral immune response in naturally and experimentally infected dogs was studied using crude and pure antigens. Both types of infections induced severe signs of visceral disease, but the symptoms observed in natural infections were more pronounced than in experimental infections. In addition, asymptomatic infections were not observed in experimentally infected animals. Disease evolution in laboratory infections was rapid and an increase in antibody titer to crude parasite antigen was correlated with the appearance and aggravation of clinical symptoms. Peripheral blood lymphocyte proliferation to crude antigen and pure gp63 was observed early following experimental infection, but was abolished once the infected dogs began to exhibit clinical signs. A similar pattern was observed in naturally infected dogs. Serum from all patent dogs showed high antibody titers to rK39 in enzyme-linked immunosorbent assays (ELISA), and reacted by western blotting with several antigens, 12 to 120 KDa, including gp63 and gp70. In the case of asymptomatic dogs. antibody titers to crude antigen were low and only a few antigens were identified by western blotting. None of the pure proteins examined, gp63, gp70, and rK39 were recognized by western blotting or ELISA. However, asymptomatic dogs exhibited specific lymphocyte proliferation to both crude antigen and the potential vaccine candidate gp63.

Bovine babesiosis. Seroprevalence and ticks associated with cattle from two different regions of Morocco.

A total of 475 bovine sera collected in 1995-1996 from 10 areas belonging to two different bioclimatic strata were tested for antibody activity to Babesia bigemina and Babesia bovis using indirect immunofluorescence (IIF). In the Gharb, the B. bovis seroprevalence was 21.7% and for B. bigemina, 10.8%. The infection rate for either or both species as determined microscopically with Giemsa-stained blood films was 18.9%. The Tiflet area was considered an endemic focus, and the seroprevalence was 42.2% for B. bovis and 40% for B. bigemina. The infection rate by stained blood film microscopy was 66.6%. In the Haouz region, only B. bovis was found, and the seroprevalence was 10.1% with 9.4% microscopically positive blood films. More than 80% of the cattle surveyed were infested by ticks and the mean infestation rate was 36 ticks per animal and 21 ticks per animal in the Gharb and Haouz, respectively. Six species were identified. Hyalomma marginatum, Hyalomma detritum, Hyalomma anatolicum Rhipicephalus bursa, Rhipicephalus sanguineous and Boophilus annulatus. Boophilus annulatus was found in both regions with high prevalence in the Gharb (31.3%). No further correlation was made between the identified species as vectors and the presence of B. bovis and B. bigemina in these areas.

Gastrointestinal and pulmonary nematode infections decrease goat productivity in Moroccan semi-arid conditions.

A herd of goats naturally infected with lungworm and gastrointestinal nematodes was divided into three groups and treated with either morantel tartrate or fenbendazole at strategic periods, i.e. in June (at pre-mating), in November (at pre-kidding) and in January (at early lactation) or left untreated. Morantel tartrate treatment (8 mg kg-1) was efficient in reducing the gastrointestinal nematode egg output and fenbendazole treatment (15 mg kg-1) was efficient in reducing the gastrointestinal nematode egg and small lungworm larvae faecal output. Reductions in mortality of adult goats and their progeny and improvement of rearing percentages were recorded in both treated groups, with fenbendazole showing a greater response than morantel tartrate. A relative risk analysis showed that mortality in goats and kids was significantly reduced in treated kids and goats. Reduction of 6.6% in kidding rates, 0.21 in prolificacy, and an increase of 1.3 in abortion rates, 8.3% in kid and 2.2% in goat mortalities, could be attributable to the small lungworm infection. Small lungworm infections seem therefore to be one of the main causes of indirect kid mortality and inadequate breeding performance of goats in the semi-arid Middle Atlas region of Morocco.

Bronchoalveolar cellular responses of goats following infections with Muellerius capillaris (Protostrongylidae, Nematoda).

The development of Muellerius capillaris in the lung of goats was associated with marked tissue damage and pronounced a cellular reaction. Using broncho-alveolar lavage, the time course of the cellular responses was studied following primary and secondary infection. During the primary infection, there was a biphasic increase in total broncho-alveolar leucocytes (an average of 294.0 +/- 137.0 cells microl[-1]) and in the absolute number of macrophages (182.0 +/- 82.0 cells ul[-1]), lymphocytes (68.5 +/- 35.0 cells microl[-1]), eosinophils (35.3 +/- 16.4 cells microl[-1]) and neutrophils (10.9 +/- 8.7 cell microl[-1]). The lung tissue reaction against worms consisted of a mild infiltration of inflammatory cells. The secondary infection resulted in significant changes in the pulmonary tissue characterised by severe inflammation, leading to widespread granulomatous formation throughout the parenchyma, hyperplasia of cells Type II and a leucocytosis in the broncho-alveolar fluids, with an anamnestic-like response by all cell types. The overall average of the total leucocytes, macrophages, lymphocytes, eosinophils and neutrophils was 529.3 +/- 347.4; 265.4 +/- 148.1; 127.3 +/- 100; 125.4 +/- 100.1 and 14.0 +/- 8.7 cells microl(-1), respectively. Secondary infection also resulted in 56% reduction of worms established in the lungs and 72.3% of L1 larval production. These data suggest that the broncho-alveolar leucocyte response to infection has an immunological basis and that the alveolar macrophages, neutrophils, eosinophils, and lymphocytes may play a significant role in lung resistance against protostrongylid nematodes.

Short report: Leishmania tropica: etiologic agent of a case of canine visceral leishmaniasis in northern Morocco.

The domestic dog has been previously demonstrated to be the reservoir of Leishmania infantum, the etiologic agent of human visceral leishmaniasis around the Mediterranean Basin. It can also be infected with L. tropica, the etiologic agent of anthroponotic cutaneous leishmaniasis in Morocco. We report a canine L. tropica visceral infection for the first time in Morocco.

Epidemiology of human visceral leishmaniasis in Taounate, a northern province of Morocco.

We report the preliminary results of an epidemiological survey carried out in the locality of Ouled Hcein, province of Taounate (North Morocco) around one visceral leishmaniasis infant case. The strain isolated from the child was characterized by three methods as Leishmania infantum and its isoenzyme pattern was indistinguishable from zymodeme MON-1. The human survey in the locality of origin of the index case did not show any additional case and the serology was negative for the whole people sampled. The canine survey showed that the highest seroprevalence of the canine disease was found in the locality of Ouled Hcein (27.1%) when compared to 4 surrounding localities. The entomological survey showed that amongst the demonstrated L. infantum vectors around the Mediterranean Basin, Phlebotomus longicuspis was the predominant species. Furthermore, the survey led to the identification of one female of P. ariasi naturally infected with L. infantum, so this species should be at least one of the vectors of this parasite in this area. Thus, this study confirms that the transmission cycle of L. infantum in North Morocco is similar to the cycle found in the remaining Mediterranean area.

Assessment of the severity of natural infections of kids and adult goats by small lungworms (Protostrongylidae, Nematoda) using macroscopic lesion scores.

Assessment of the severity of natural infections of kids and adult goats by small lungworms using macroscopic lesion scores was carried out on 476 lungs originating from the Rabat area of Morocco. The prevalence of infection was 98% in kids and 100% in adult goats. The diaphragmatic lobes were the preferential site for protostrongylids. The average number of nodules (mostly Muellerius capillaris) and lobular lesions (mostly Protostrongylus rufescens and Cystocaulus ocreatus) was 174 and 9 per pair of lungs respectively, indicating that the amount of lung tissue rendered inactive in heavy infections was considerable. Up to 19.9% kids or 34.2% adult goats had heavy infection based on nodular lesions (more than 200 nodules); 61% and 68% of kids and adult goats respectively had heavy infection based on lobular lesions (more than four lobular lesions per pair of lungs). The proportion of the total lung surface occupied by protostrongylid lesions was 35.1% in kids and 23.5% in adult goats, suggesting that small lungworm infections may significantly contribute to the debilitation of infected caprines in the area.

Impaired pulmonary gas exchange in ewes naturally infected by small lungworms.

Respiratory rate and blood gases were studied in 2 groups of ewes: the ewes in group 1 (9 ewes) acted as uninfected controls and those in group 2 (6 ewes) were infected with small lungworms (Muellerius, Cystocaulus, Protostrongylus and < 1% Neostrongylus). The respiratory rate was higher in infected (49 +/- 19 breath min-1) than in uninfected ewes. (20 +/- 3 breath min-1); it was strongly reduced after treatment (49 vs 22) in infected ewes. The partial carbon dioxide arterial tension (PCO2), total CO2 and HCO3- were higher (respectively 77 vs 39 mmHg, 38 vs 23 mmol-1 and 35 vs 23 mmol-1) in infected compared with uninfected ewes, whereas arterial pH (7.2 vs 7.4) and partial oxygen tension PO2 were lower (41 vs 81 mmHg) in infected ewes. Group 2 was treated with fenbendazole (at 15 mg kg-1 bodyweight) to eliminate small lungworms, and the respiratory rate and blood gases were measured 3 weeks after treatment. The values after treatment were similar to those in uninfected ewes. It is concluded that heavy infections by small lungworms in ewes impairs gas exchange, but that gas exchange improves rapidly after treatment.

A quantitative approach to nematode lungworm burdens in goats.

Nematode lungworm burdens are difficult to evaluate of necropsy. The recovery of protostrongylid worms was achieved by three different post-mortem quantification techniques. Perfusion of the lungs under watertap pressure was successful in washing out Protostrongylus rufescens and Cystocaulus ocreatus but not Muellerius capillaris and Neostrongylus. Incubation of the lungs by pepsin and hydrochloric acid solution prior to perfusion helped to recover trapped Muellerius and Neostrongylus. Worm nodules were classified into type A, B and C, on increasing calcification process. Examination of these nodules showed that 75 to 80% of type A and B contained a parasite. Worms recovered by perfusion added to the sum of type A and B nodules were used to construct formula for quantifying the total lungworm burdens from naturally infected goat lungs and may provide a reasonable basis for assessing anthelmintic efficacy.

Epidemiological aspects of lungworm infections of goats in Morocco.

The results of a survey of lungworm infections in goats in the Middle Atlas and Rabat areas in Morocco during 1990-1992 are reported. Five species were recorded: Dictyocaulus filaria, Protostrongylus rufescens, Cystocaulus ocreatus, Muellerius capillaris and Neostrongylus linearis. The parasitological profile of protostrongylid species was represented by Muellerius (69-78%), Protostrongylus (16-25%) and Cystocaulus (5-6%) in the Rabat and Middle Atlas areas. Neostrongylus was virtually non-existent (under 1%) in both regions. Multigeneric infection involving several species of lungworms reached 54% in Rabat and 88% in Middle Atlas. Dictyocaulus infection of goats does not appear to be a serious problem. Infection rates of 40% and 50%, and average worm burdens of three and five worms per kid and adult goat were recorded in autumn in the Rabat area. A similar pattern was noted in Middle Atlas. In contrast, the incidence of small lungworm infections in goats is widespread at levels likely to be of economic significance. The level of infection was considerably higher than the Dictyocaulus infection and the infection rate was virtually 100% in both age groups in the two areas. The overall worm burdens averaged 77.03 +/- 22.6 parasites per adult goat and 44.16 +/- 16.3 per kid in the Rabat area, whereas the corresponding figures in Middle Atlas were 51.48 +/- 16.65 and 34.06 +/- 2.69 worms. The periods of high risk of infection by small lungworms were autumn, early winter and late spring-early summer. However, the heaviest infection by adult worms and the highest larval excretion were observed in late autumn and winter when molluscs were heavily infected. The periparturient period seemed to exert a positive influence on protostrongylid larval production. The output of first stage larvae (L1) of lungworms was significantly higher in goats than in sheep. Thus, goats may play a greater role in pasture contamination. The epidemiological factors influencing the seasonal fluctuations of lungworms are discussed and a timetable of recommended treatments is suggested.

Gross and light-microscopic features of ovine pulmonary hydatidosis and verminous pneumonias in Morocco.

Verminous pneumonias appear to be common in sheep in Morocco, therefore, a systematic study was undertaken to classify the pulmonary changes induced by various parasites in Morocco. A total of 613 pairs of lungs with parasitic pneumonias were diagnosed in 1152 young and adult sheep either slaughtered at two abattoirs in Morocco (487 out of 1152 sheep) or received at necropsy services (126 out of 1152 sheep) over a 15-month period. Based on gross and microscopic findings, four types of pulmonary changes were classified. Included were those associated with: 1. The larvae of Taenia echinococcus (Echinococcus granulosus (canine tapeworm); 520 out of 613 lungs (84.8%)); 2. Muellerius capillaris (450 out of 613 lungs (79.9%)); 3. Protostrongylus rufescens (375 out of 613 lungs (61.1%)); and 4. Dictyocaulus filaria (285 out of 613 lungs (46.4%)). Mixed infestations, involving the presence of two, three, or four species of parasites in the same lung, were encountered in 325 out of 613 (53%) lungs studied. Red-to-brownish consolidated areas, confined to the cranial parts of the lung, were observed frequently in some lungs affected with M. capillaris and P. rufescens. In most of the lungs, co-existent emphysematous, atelectatic, and abscessed areas were seen.

[Eimeria tenella and Eimeria acervulina: an antigenic stimulation in vitro of cells from immune chickens induced by adoptive transfer of protection against avian coccidiosis]. / Eimeria tenella et Eimeria acervulina: une stimulation antigénique in vitro des cellules provenant de poulets immuns induit le transfert adoptif de la protection contre les coccidioses aviaires.

The transfer of 5 x 10(7) or 10(8) spleen cells from E tenella-infected chickens to virgin animals after 12-20-h in vitro stimulation with whole sporozoite homogenates confers significant protection to recipients. The oocyst contents of ceca on d 7 post-infection with 20,000 E tenella oocysts were (1.33 +/- 1.10) x 10(6) in chickens which received 5 x 10(7) immune cells after 20-h in vitro stimulation and (4.64 +/- 2.85) x 10(6) in chickens receiving 5 x 10(7) stimulated cells from normal chickens (85% protection). Adoptive transfer by spleen cells revealed an asymmetric cross-protection between E tenella and E acervulina. Spleen cells from E tenella immune chickens protected only against a subsequent infection with the same parasite, while spleen cells from E acervulina immune chickens protected against infection with E acervulina (78%) but also against infection with E tenella (68% protection). The common antigen permits better stimulation, but common surface sporozoite antigens purified from E tenella sporozoites via anti-E acervulina biliary antibodies are capable of stimulating both types of cells without, however, changing their properties.