Excretion of Histomonas meleagridis following experimental co-infection of distinct chicken lines with Heterakis gallinarum and Ascaridia galli

Background Histomonosis is a severe re-emerging disease of poultry caused by Histomonas meleagridis, a protozoan parasite which survives in the environment via the cecal worm Heterakis gallinarum. Following infection, the parasites reside in the ceca and are excreted via host feces. In the present work, male birds of conventional broiler (Ross 308, R), layer (Lohmann Brown Plus, LB) and a dual-purpose (Lohmann Dual, LD) chicken line were infected with 250 embryonated eggs of Ascaridia galli and Heterakis gallinarum, respectively, with the latter nematode harboring Histomonas meleagridis, to investigate a co-infection of nematodes with the protozoan parasite in different host lines. Methods In weekly intervals, from 2 to 9 weeks post infection (wpi), individual fecal samples (n = 234) from the chickens were collected to quantify the excretion of H. meleagridis by real-time PCR and to determine the number of nematode eggs per gram (EPG) in order to elucidate excretion dynamics of the flagellate and the nematodes. This was further investigated by indirect detection using plasma samples of the birds to detect antibodies specific for H. meleagridis and worms by ELISA. The infection with H. meleagridis was confirmed by histopathology and immunohistochemistry to detect the flagellate in the cecum of representing birds. Results The excretion of H. meleagridis could already be observed from the 2nd wpi in some birds and increased to 100% in the last week of the experiment in all groups independent of the genetic line. This increase could be confirmed by ELISA, even though the number of excreted H. meleagridis per bird was generally low. Overall, histomonads were detected in 60% to 78% of birds with temporary differences between the different genetic lines, which also showed variations in the EPG and worm burden of both nematodes. Conclusions The infection with H. gallinarum eggs contaminated with H. meleagridis led to a permanent excretion of the flagellate in host feces. Differences in the excretion of H. meleagridis in the feces of genetically different host lines occurred intermittently. The excretion of the protozoan or its vector H. gallinarum was mostly exclusive, showing a negative interaction between the two parasites in the same host. Graphic abstract

Diurnal variation in egg excretion by Heterakis gallinarum

Periodicity in nematode egg excretion may be of evolutionary origin as it can favour dispersal of the eggs in the environment. We investigated whether egg excretion by Heterakis gallinarum shows a repeatable pattern of periodicity. The faecal egg concentration and total number of eggs excreted within 4-h intervals were significantly affected by the sampling time within 1 day, but remained unaffected by the sampling day or interaction effects. By contrast, the total number of eggs excreted within 24 h did not differ among the 4 days of the study, collectively indicating repeatable egg excretion patterns. Both host feces and parasite egg excretion increased from night to late afternoon, followed by a decrease in the evening, resulting in higher egg excretion during daytime than the dark period. Feces excretion and worm fecundity showed overlapping diurnal rhythms with similarly timed phases, suggesting the existence of synchronicity between the host feces and nematode egg excretion patterns. We conclude that egg excretion by H. gallinarum is synchronized with host feces excretion and is higher during the daytime than during the dark period. This overlaps with the maximum activity of the day-active host and allows a maximal dispersal of the eggs in the environment.

Evaluation of Kato-Katz and spontaneous sedimentation methods for the diagnosis of platynosomiasis in Neotropical primates

Platynosomiasis is a parasitic infection reported in non-human primates, including marmosets, and is frequently difficult to diagnose. In this study, the Kato-Katz method and the spontaneous sedimentation method were evaluated for their usefulness in identifying Platynosomum eggs in fecal samples from Callithrix penicillata that naturally harbor Platynosomum illiciens. Spontaneous sedimentation allowed the diagnosis of 41.7% (5/12) and 66.7% (8/12) of infected marmosets from one and three slides, respectively, prepared from the same fecal sample. The examination of a single Kato-Katz thick smear detected 83.3% (10/12) of infection cases. The analysis of feces on three different days increased the rate of diagnosis, since 75% (9/12) and 100% (12/12) of the primates with platynosomiasis were identified using serial spontaneous sedimentation (3 slides/day) and the Kato-Katz method, respectively. The mean number of Platynosomum eggs per gram of feces determined via the Kato-Katz method was 71.7 (8-240). The spontaneous sedimentation method when performed in series is acceptable for the diagnosis of platynosomiasis. However, the Kato-Katz method, which was here used for the first time to detect this infection, has a higher diagnostic sensitivity and the advantage that a quantitative analysis of the eggs released in the host feces is possible.

Evidence for Extraintestinal Growth of Bacteroidales Originating from Poultry Litter

ABSTRACTWater quality monitoring techniques that target microorganisms in the orderBacteroidalesare potential alternatives to conventional methods for detection of fecal indicator bacteria.Bacteroidalesand members of the genusBacteroideshave been the focus of microbial source tracking (MST) investigations for discriminating sources of fecal pollution (e.g., human or cattle feces) in environmental waters. For accurate source apportionment to occur, one needs to understand both the abundance ofBacteroidesin host feces and the survival of these host-associated microbial markers after deposition in the environment. Studies were undertaken to evaluate the abundance, persistence, and potential for growth ofBacteroidalesoriginating from poultry litter under oxic and anoxic environmental conditions.Bacteroidalesabundance, as determined by quantitative PCR (qPCR) with GenBac primers and probe, increased 2 to 5 log gene copies ml−1and 2 log gene copies g litter−1under most conditions during incubation of poultry litter in a variety of laboratory microcosm and field mesocosm studies. DNA sequencing of theBacteroidalesorganisms in the litter identified taxa with sequences corresponding exactly to the GenBac primer and probe sequences and that were closely related toBacteroides uniformis,B. ovatus, andB. vulgatus. These results suggest that MST studies using qPCR methods targetingBacteroidalesin watersheds that are affected by poultry litter should be interpreted cautiously. Growth ofBacteroidalesoriginating from poultry litter in environmental waters may occur whileBacteroidalesgrowth from other fecal sources declines, thus confounding the interpretation of MST results.

Female Spider Wasps, Anoplius splendens Driesbach (Hymenoptera: Pompilidae), Learn to Associate the Odor of Host Feces With the Presence of the Host

Laboratory studies were conducted to determine whether or not adult female wasps, Anoplius splendens (Dreisbach), can learn a chemical stimulus (host feces) associated with host microhabitats. In a two-choice, static-air olfactometer, wasps previously exposed to hosts only in association with one stimulus (filter paper conditioned with odors from feces of the host spider, Drassodes auriculoides Barrows) exhibited a greater tendency to visit exclusively, and spend more time in, chambers containing a source of that stimulus as compared to control wasps exposed to paper with no host odors. The capacity for learning olfactory cues based on previous encounters with hosts should enhance the ability of wasps to accurately identify microhabitats where suitable hosts are most likely to be located.