Viability of Ascaris suum eggs in stored raw and separated liquid slurry.

Separation of pig slurry into solid and liquid fractions is gaining importance as a way to manage increasing volumes of slurry. In contrast to solid manure and slurry, little is known about pathogen survival in separated liquid slurry. The viability of Ascaris suum eggs, a conservative indicator of fecal pollution, and its association with ammonia was investigated in separated liquid slurry in comparison with raw slurry. For this purpose nylon bags with 6000 eggs each were placed in 1 litre bottles containing one of the two fractions for 308 days at 5 °C or 25 °C. Initial analysis of helminth eggs in the separated liquid slurry revealed 47 Ascaris eggs per gramme. At 25 °C, egg viability declined to zero with a similar trend in both raw slurry and the separated liquid slurry by day 308, a time when at 5 °C 88% and 42% of the eggs were still viable in separated liquid slurry and raw slurry, respectively. The poorer survival at 25 °C was correlated with high ammonia contents in the range of 7.9-22.4 mM in raw slurry and 7.3-23.2 mM in liquid slurry compared to 3.2-9.5 mM in raw slurry and 2.6-9.5 mM in liquid slurry stored at 5 °C. The study demonstrates that at 5 °C, A. suum eggs have a higher viability in separated liquid slurry as compared to raw slurry. The hygiene aspect of this needs to be further investigated when separated liquid slurry is used to fertilize pastures or crops.

Ascaridia galli in chickens: intestinal localization and comparison of methods to isolate the larvae within the first week of infection.

This study was conducted to observe the localization and to compare methods for isolation of minute Ascaridia galli larvae in chicken intestine. Firstly, six 7-week-old layer pullets were orally infected with 2,000 embryonated A. galli eggs and necropsied either at 3, 5 or 7 days post infection (dpi). More than 95 % of the recovered larvae were obtained from the anterior half of the jejunoileum, suggesting this part as the initial predilection site for A. galli larvae. Secondly, the intestinal wall of one layer pullet infected with 20,000 A. galli eggs 3 days earlier was digested in pepsin-HCl for 90 min. The initial 10 min of digestion released 51 % of the totally recovered larvae and the last 30 min of continuous digestion yielded only 5 %. This indicates that the majority of larvae were located superficially in the intestinal mucosa. Thirdly, 48 7-week-old layer pullets were infected with 500 A. galli eggs and necropsied at 3 dpi to compare three different larval isolation methods from the intestinal wall, viz., EDTA incubation, agar-gel incubation and pepsin-HCl digestion, resulting in mean percentages of the recovered larvae: 14.4, 18.2 and 20.0 %, respectively (P = 0.15). As conclusion, we recommended Pepsin-HCl digestion as the method of choice for larval recovery from the intestinal wall in future population dynamics study due to high efficiency and quick and simple detection. The agar-gel method was considered to be a prerequisite for molecular and immunological investigations as the larvae were more active and fully intact.

Simulating transmission and control of Taenia solium infections using a Reed-Frost stochastic model.

The transmission dynamics of the human-pig zoonotic cestode Taenia solium are explored with both deterministic and stochastic versions of a modified Reed-Frost model. This model, originally developed for microparasitic infections (i.e. bacteria, viruses and protozoa), assumes that random contacts occur between hosts and that hosts can be either susceptible, infected or 'recovered and presumed immune'. Transmission between humans and pigs is modelled as susceptible roaming pigs scavenging on human faeces infected with T. solium eggs. Transmission from pigs to humans is modelled as susceptible humans eating under-cooked pork meat harbouring T. solium metacestodes. Deterministic models of each scenario were first run, followed by stochastic versions of the models to assess the likelihood of infection elimination in the small population modelled. The effects of three groups of interventions were investigated using the model: (i) interventions affecting the transmission parameters such as use of latrines, meat inspection, and cooking habits; (ii) routine interventions including rapid detection and treatment of human carriers or pig vaccination; and (iii) treatment interventions of either humans or pigs. It is concluded that mass-treatment can result in a short term dramatic reduction in prevalence, whereas interventions targeting interruption of the life cycle lead to long-term reduction in prevalence.

Environmental contamination and transmission of Ascaris suum in Danish organic pig farms.

BACKGROUND: Although Ascaris suum is the most common pig nematode, the on-farm transmission dynamics are not well described. METHODS: We performed a 1-year field study on five organic pig farms, mapping egg contamination levels in pens and pasture soil as well as faecal egg counts in starter pigs, finisher pigs, dry and lactating sows. The uppermost bedding material was sampled from three pen areas (resting, intermediate and latrine) of shallow and deep litter pens. RESULTS: Ascaris suum was found on all farms. Averaged across farm and season, the prevalence of A. suum was 48, 64, 28 and 15% in starters, finishers, dry and lactating sows, respectively. For starters and finishers, the prevalence varied with season increasing towards the end of the year when 83-96% of finishing pigs from each farm had fresh liver white spots. Farrowing pastures were contaminated with a mean of 78-171 larvated eggs/kg dry soil depending on farm, while pastures for starter pigs contained 290-5397 larvated eggs/kg dry soil. The concentration of eggs in soil was highest in the autumn. Indoors, all pen areas were contaminated with A. suum eggs at comparable levels for shallow and deep litter. Overall there were 106, 445 and 1331 eggs/g dry straw in the resting, intermediate and latrine areas, respectively. However, more eggs were undergoing development in resting areas (44%) compared to intermediate (33%) and latrine areas (13%). Irrespective of area, more eggs were undergoing development in the autumn, but overall there were very few fully developed (i.e., infective) eggs in the bedding material. Laboratory embryonation of eggs from the bedding material nevertheless revealed that an overall mean of 79% of the eggs were viable. CONCLUSION: The organic pigs of all ages were continuously exposed to A. suum, but mainly younger animals were infected. Deep litter appeared to be a less important source of A. suum eggs than previously believed compared to shallow litter. Long-term pasture rotation to eliminate pasture contamination was not possible, and control programs should therefore include thorough cleaning indoors and composting/long-term storage of bedding material and manure to inactivate eggs and reduce transmission to pigs.

The impact of natural helminth infections and supplementary protein on growth performance of free-range chickens on smallholder farms in El Sauce, Nicaragua.

Three on-farm studies were conducted in Nicaragua during three consecutive years (1999-2001) to assess the impact of natural helminth infections on growth performance of free-range chickens aged 3-4 months. On all participating farms, half of the chickens were treated regularly with anthelmintics (Trifen avicola - a combined formulation of piperazine, phenothiazine and dichlorophen - or albendazole) to express the growth potential of non-infected birds, whereas the other half served as non-treated controls. In 1999, treated chickens had a 39% higher weight gain compared to the control group 6 weeks after the first treatment on 15 farms. In 2000 and 2001, treated chickens had similar weight gain as the control group 10 weeks after the first treatment on 7 farms and 12 farms, respectively. The main reason for the very-different weight gain figures seems to be the weather conditions. In 1999, the study site experienced a rainy season with precipitation far above average, whereas in 2000 and 2001 the rainy seasons had precipitations far below average. Based on these findings, routine use of anthelmintics in the study area would only be recommended in wet years when production losses due to helminth infections seem to be pronounced. In 2001, the study set-up included an assessment of the effect of protein supplementation (soybean) on growth on six farms. Supplemented chickens (treated and non-treated with anthelmintics) had 17% higher weight gain than non-supplemented. Protein supplementation affected neither worm burdens nor faecal egg counts for any of the studied helminths. The post-mortem examinations showed that Trifen reduced burdens of Ascaridia galli, Heterakis gallinarum, and cestodes (efficacies of 100, 100 and 67%, respectively). Albendazole reduced burdens of H. gallinarum (efficacy of 100%). Efficacies against other helminths were difficult to assess due to low worm burdens. Chickens treated with albendazole had lower Ascaridia and Heterakis faecal egg counts than non-treated chickens.

Improving pig husbandry in tropical resource-poor communities and its potential to reduce risk of porcine cysticercosis.

To minimise the risk of cysticercosis in pigs it is necessary to raise pigs in confinement. The prevailing production system using free-range pigs is apparently very resilient although economic studies have shown that these traditional production systems are wasteful and unprofitable due to poor feed conversion, high mortality rates, low reproductive rates and poor final products. However, experiences from Africa show that intensive pig farming is stagnant and the sustainability of the traditional sector is better than that of the intensive sector. Examples from various African countries are given on the failure of intensive pig farming. This apparent paradox has various explanations. The lower fixed cost of traditional pig production compared with intensive production is one. Another explanation is that many households have some kind of kitchen waste, which can be exploited by a pig, but there is only enough for the partial feeding of a single pig. A third explanation of the paradox is that the pig has functions that are not reflected in a simple economic balance. The pig is a source of capital income, which can be realised at times of major expenses, and it can also be used as a way to put aside small amounts of money, which alternatively might evaporate. The pig's scavenging behaviour has clear nutritional benefits. Thus, a diet consisting of e.g. maize or sorghum, which are some of the feeds available on the small farms, will only provide approximately 30% of the pigs requirements of lysine and methionine, which are the most limiting amino-acids in pig feeds. Simulations with data available for green feeds and material of animal origin show that a 20% "supplement" from the fields may increase the amino-acid provision to about 80% of the optimum. If pigs are kept enclosed this supplement has to be fed to the pig which involves purchase and labour costs. The paper discusses the various options in terms of feeding, housing and use of genetic resources for the improvement of pig husbandry in tropical resource-poor countries.

Use of Artemisia annua as a natural coccidiostat in free-range broilers and its effects on infection dynamics and performance.

This work investigated the preventive effect of Artemisia annua L. dried leaves supplied as a botanical coccidiostat to two broiler genotypes reared in a Danish free-range system in a factorial experiment (two genotypes and ± supplement of dried A. annua leaves). The genotypes White Bresse L40, a pure slow-growing line, and Kosmos 8 Ross, a hybrid genotype with medium growing characteristics, were used. Broilers were raised indoor until 29-days-old and kept free of parasites. Twelve groups of 30 randomly selected broilers were placed in the range forming three replicates for each treatment combination. The paddocks were cultivated with a mix of grass and clover. A separate group of broilers was naturally infected with Eimeria spp. oocysts and five animals nominated as "seeders" were introduced to the above mentioned 12 groups, 10 days after its formation, with each group consisting of 35 animals per plot. This infection strategy was meant to imitate the transmission pathway observed at farm level. Ten individual birds from each of the 12 groups, in total 120 animals of mixed sex, were monitored twice weekly for 30 days for oocysts excretion. PCR of pooled faecal samples, oocyst morphology and localization upon necropsy were used to identify the Eimeria species involved in the infection. In general, broilers from both genotypes in the range coped well with a coccidia infection caused by Eimeria acervulina and Eimeria maxima as no clinical symptoms, or deaths, were reported during the experiment. In general, broilers supplemented with A. annua dried leaves showed a significantly (p<0.05) reduced number of excreted oocysts during the infection with no interaction to genotype. Females generally had a significantly higher shedding of oocysts than males (p<0.05). The overall body weight gain and the daily weight gain when infection was subdued showed a three-way interaction among genotype, sex and treatment - accounted mainly for the fact that Kosmos females responded positively to the Artemisia treatment while Kosmos males responded negatively, and only minor differences were found between sexes for the White Bresse genotype. In conclusion, supply of A. annua dried leaves as a botanical coccidiostat significantly reduced oocyst output in free ranged broilers and thus may form part of a strategy to prevent commercial losses.

Prevalence of strongyles and efficacy of fenbendazole and ivermectin in working horses in El Sauce, Nicaragua.

Horses, mules and donkeys are indispensable farming and working animals in many developing countries, and their health status is important to the farmers. Strongyle parasites are ubiquitous in grazing horses world-wide and are known to constitute a threat to equine health. This study determined the prevalence of strongyle infection, the efficacy of ivermectin and fenbendazole treatment, and strongyle re-infection rates of working horses during the dry months in Nicaragua. One hundred and five horses used by farmers for transport of people and goods were randomly allocated into three treatment groups, i.e., the IVM group treated with ivermectin, the FBZ group treated with fenbendazole and the control group treated with placebo. Determined by pre-treatment faecal egg counts (FECs), horses showed a high prevalence (94%) of strongyle parasites with high intensities of infection (mean FEC of 1117 eggs per gram (EPG) with an SD of 860 EPG, n=102). Body condition scores of all horses ranged from 1.5 to 3.5 with a mean of 2.4 (scales 1-5). Fourteen days after treatment faecal egg count reductions (FECRs) were 100% and 94% in the IVM and the FBZ groups, respectively. The egg reappearance period (ERP) defined as the time until the mean FEC reached 20% of the pre-treatment level, was estimated as 42 days for the FBZ group and 60 days for the IVM group. Individual faecal cultures were set up and the larval differentiation revealed a 36% prevalence of Strongylus vulgaris before treatment (n=45). In the FBZ group, 25% of the horses were S. vulgaris-positive 70 days post treatment compared to 11% in the IVM group. Our results indicate that strongyle infection intensities in Nicaragua are high and that S. vulgaris is endemic in the area. Furthermore, efficacies and ERPs of IVM and FBZ were within the expected range with no signs of anthelmintic resistance.