The Comparison of parasite eggs and protozoan cysts of urban raw wastewater and efficiency of various wastewater treatment systems to remove them

One of the most important quality characteristics associated with wastewater reuse in agriculture is the microbial quality. This study aimed to determine the efficiencies of Ghasreshirin (constructed wetland), Islamabadgharb and Gilangharb wastewater treatment plants (stabilization ponds), Sarpolezahab and Paveh (extended aeration activated sludge) and Kermanshah (conventional activated sludge) in the removal of protozoan cysts and parasitic eggs. This study was carried out during six months and samples were collected at weekly intervals from influent and effluent of the wastewater plants. In order to determine the concentration of ova, 288 samples were analyzed by Mc Master Slide according to Bailenger method. No parasite eggs or protozoan cysts were detected in the effluents of the constructed wetland or stabilization ponds systems. The extended aeration activated sludge system of Sarpolezahab removed 99-100% of parasite eggs and ≥99% of protozoan cysts. The respective values for extended aeration activated sludge system of Paveh were 97.5-100% and ≥99%. However, the conventional activated sludge of Kermanshah removed 97-99% and 99-100% of parasite eggs and protozoan cysts, respectively. According to the results, removal efficiency for cysts and parasite eggs in natural systems (constructed wetland and stabilization ponds) is better than mechanical systems (extended aeration activated sludge and conventional activated sludge). The effluent quality of all systems in terms of nematode eggs is consisted to Engelberg index (nematode eggs count: 1 ≥ counts per liter)

Long-term survival of Ascaris suum and Trichuris suis eggs in relation to pasture management

Background: Organic pig production systems are commonly characterized by high helminth prevalences. This problem is partly associated with access to outdoor facilities such as pastures and more knowledge is needed on long-term pasture infectivity patterns to improve farmer advisory services and guidelines on pasture management. Methods: Six identical paddocks were originally contaminated in the spring to autumn of 2001 by pigs infected with high levels of Ascaris suum and low levels of Trichuris suis. Since then, no further eggs have been deposited and 3 of the paddocks have been ploughed to a depth of 20 to 28 cm and re-sown once a year while 3 paddocks remained untouched apart from yearly cutting of the vegetation. In the late spring and late autumn of 2001, 2002, 2003, and 2004 as well as in the autumn of 2005, 2007, and 2010, survival of parasite eggs was measured by analysis of soil samples and by recovery of worms from short-term exposed helminth naïve tracer pigs. Results: Following a high initial egg mortality in 2001-2002, the number of parasite eggs in the soil declined slowly over time for both species. In 2001, very few T. suis eggs developed to infectivity. The tracer data show that overall pasture infectivity for T. suis did not peak until 3-4 years after the initial contamination. Preliminary data from 2010 indicate that T. suis is still present on the paddocks, though at very low levels. Infective A. suum eggs were detected in 2001 and paddock infectivity levels peaked within 2 years after contamination, resulting in livers with very high numbers of white spots, irrespective of paddock treatment. Transmission of T. suis was more consistently reduced by ploughing compared to A. suum. Conclusion: Development and maturation of A. suum eggs and especially T. suis eggs was overall slower than expected, indicating that pasture rotation schemes should ideally exceed 3 years. However, 9 years after initial contamination, both species were still detected and A. suum pasture infectivity was still too high for the paddocks to be suitable for pigs. Overall, transferring the eggs deeper into the soil by ploughing appeared to reduce parasite transmission

Feasibility of Using Cryostored Colorado Potato Beetle (Coleoptera: Chrysomelidae) Eggs for Rearing \u3ci\u3eEdovum Puttleri\u3c/i\u3e (Hymenoptera: Eulophidae)

Cryostored eggs of Colorado potato beetle, Leptinotarsa decemlineata (Say) eggs were suitable hosts for Edovum puttleri. Parasitism rates were low, however this study was first to show that rearing the parasite on eggs stored at ultra low temperatures (-70 0 C) is feasible. This method of storage will facilitate mass production of E. puttleri as well as prevent loss of the parasite in the event of a crash in the Colorado potato beetle colony

Metazoan-protozoan parasite co-infections and host body weight in St Kilda Soay sheep

For hundreds of years, the unmanaged Soay sheep population on St Kilda has survived despite enduring presumably deleterious co-infections of helminth, protozoan and arthropod parasites and intermittent periods of starvation. Important parasite taxa in young Soay sheep are strongyles (Trichostrongylus axei, Trichostrongylus vitrinus and Teladorsagia circumcincta), coccidia (11 Eimeria species) and keds (Melophagus ovinus) and in older animals, Teladorsagia circumcincta. In this research, associations between the intensity of different parasite taxa were investigated. Secondly, the intensities of different parasite taxa were tested for associations with variation in host weight, which is itself a determinant of over-winter survival in the host population. In lambs, the intensity of strongyle eggs was positively correlated with that of Nematodirus spp. eggs, while in yearlings and adults strongyle eggs and coccidia oocysts were positively correlated. In lambs and yearlings, of the parasite taxa tested, only strongyle eggs were significantly and negatively associated with host weight. However, in adult hosts, strongyles and coccidia were independently and negatively associated with host weight. These results are consistent with the idea that strongyles and coccidia are exerting independent selection on Soay sheep.</p

Hatching Strategies in Monogenean (Platyhelminth) Parasites that Facilitate Host Infection

In parasites, environmental cues may influence hatching of eggs and enhance the success of infections. The two major endoparasitic groups of parasitic platyhelminths, cestodes (tapeworms) and digeneans (flukes), typically have high fecundity, infect more than one host species, and transmit trophically. Monogeneans are parasitic flatworms that are among the most host specific of all parasites. Most are ectoparasites with relatively low fecundity and direct life cycles tied to water. They infect a single host species, usually a fish, although some are endoparasites of amphibians and aquatic chelonian reptiles. Monogenean eggs have strong shells and mostly release ciliated larvae, which, against all odds, must find, identify, and infect a suitable specific host. Some monogeneans increase their chances of finding a host by greatly extending the hatching period (possible bet-hedging). Others respond to cues for hatching such as shadows, chemicals, mechanical disturbance, and osmotic changes, most of which may be generated by the host. Hatching may be rhythmical, larvae emerging at times when the host is more vulnerable to invasion, and this may be combined with responses to other environmental cues. Different monogenean species that infect the same host species may adopt different strategies of hatching, indicating that tactics may be more complex than first thought. Control of egg assembly and egg-laying, possibly by host hormones, has permitted colonization of frogs and toads by polystomatid monogeneans. Some monogeneans further improve the chances of infection by attaching eggs to the host or by retaining eggs on, or in, the body of the parasite. The latter adaptation has led ultimately to viviparity in gyrodactylid monogeneans

Non-midical control of parasitic worms in pigs

Generally there is a higher prevalence of intestinal parasites in organic pigs compared to conventional indoor pigs. It may be possible to reduce infection levels by ensuring that new animals are parasite free, using a moderate stocking rate, co-grazing cows and sows, using noserings, altering feed composition and feeding the pigs predatious fungi. In addition, paddock rotation is recommended in order to remove the pigs from the infectious parasite stages (eggs and larvae). Resent results show that the free-living larvae of the nodular worm do not survive for long on pasture. Overall, the nodular worm is considered to be less of a problem than other parsites. Eggs from the large round worm and especially the whipworm can take long to become infective but may in return survive several years in the soil. It seems as if ploughing may reduce the transmission of whipworm considerably, whereas the effect on the large round worm is not as strong. The large differences between the three parasites mean that control strategies may have to be designed according to the parasites present in a given herd

Modelling the consequences of targeted selective treatment strategies on performance and emergence of anthelmintic resistance amongst grazing calves

The development of anthelmintic resistance by helminths can be slowed by maintaining refugia on pasture or in untreated hosts. Targeted selective treatments (TST) may achieve this through the treatment only of individuals that would benefit most from anthelmintic, according to certain criteria. However TST consequences on cattle are uncertain, mainly due to difficulties of comparison between alternative strategies. We developed a mathematical model to compare: 1) the most ‘beneficial’ indicator for treatment selection and 2) the method of selection of calves exposed to Ostertagia ostertagi, i.e. treating a fixed percentage of the population with the lowest (or highest) indicator values versus treating individuals who exceed (or are below) a given indicator threshold. The indicators evaluated were average daily gain (ADG), faecal egg counts (FEC), plasma pepsinogen, combined FEC and plasma pepsinogen, versus random selection of individuals. Treatment success was assessed in terms of benefit per R (BPR), the ratio of average benefit in weight gain to change in frequency of resistance alleles R (relative to an untreated population). The optimal indicator in terms of BPR for fixed percentages of calves treated was plasma pepsinogen and the worst ADG; in the latter case treatment was applied to some individuals who were not in need of treatment. The reverse was found when calves were treated according to threshold criteria, with ADG being the best target indicator for treatment. This was also the most beneficial strategy overall, with a significantly higher BPR value than any other strategy, but its degree of success depended on the chosen threshold of the indicator. The study shows strong support for TST, with all strategies showing improvements on calves treated selectively, compared with whole-herd treatment at 3, 8, 13 weeks post-turnout. The developed model appeared capable of assessing the consequences of other TST strategies on calf populations

Infection of Gammarus duebeni populations by two vertically transmitted microsporidia; parasite detection and discrimination by PCR–RFLP

We screened a population of the brackish water crustacean Gammarus duebeni from the Isle of Cumbrae for the presence of vertically transmitted microsporidia. We compared 2 screening techniques; light microscopy and PCR-based detection using generic 16S rDNA microsporidian primers. Fifty percent of females from this population tested positive for vertically transmitted microsporidia. The PCR screen was 100% efficient in comparison with existing LM based screening. In addition, the PCR screen produced bands of 2 sizes suggesting that more than 1 species of microsporidian was present. Sequencing revealed 2 distinct species of vertically transmitted microsporidia; 33% of females were infected with the feminizer Nosema granulosis and 17% were infected with a new species which we provisionally designate Microsporidium sp. On the basis of sequence information, we developed a discriminatory PCR–RFLP test based on MspI and HaeIII digests. This screen allows rapid detection and discrimination of vertically transmitted microsporidia in natural field populations. We applied the PCR–RFLP screen to a second G. duebeni population from the Isle of Man. This population also hosted these 2 parasite species. In total 45% of females harboured N. granulosis and 10% harboured Microsporidium sp. No dual-infected individuals were found in either population. The occurrence of 2 vertically transmitted parasites within a population has implications for our understanding of parasite–host relationships in the field and we discuss factors affecting the dynamics of parasite–parasite competition and coexistence

A role for eosinophils in the intestinal immunity against infective Ascaris suum larvae

The aim of this study was to explore the mechanisms of resistance against invading Ascaris suum larvae in pigs. Pigs received a low dose of 100 A. suum eggs daily for 14 weeks. This resulted in a .99% reduction in the number of larvae that could migrate through the host after a challenge infection of 5000 A. suum eggs, compared to naı¨ve pigs. Histological analysis at the site of parasite entry, i.e. the caecum, identified eosinophilia, mastocytosis and goblet cell hyperplasia. Increased local transcription levels of genes for IL5, IL13, eosinophil peroxidase and eotaxin further supported the observed eosinophil influx. Further analysis showed that eosinophils degranulated in vitro in response to contact with infective Ascaris larvae in the presence of serum from both immune and naı¨ve animals. This effect was diminished with heat-inactivated serum, indicating a complement dependent mechanism. Furthermore, eosinophils were efficient in killing the larvae in vitro when incubated together with serum from immune animals, suggesting that A. suum specific antibodies are required for efficient elimination of the larvae. Together, these results indicate an important role for eosinophils in the intestinal defense against invading A. suum larvae