PCR detection of Heterakis gallinarum in environmental samples

Heterakis gallinarum is a widely distributed cecal nematode that parasitizes gallinaceous birds including chickens and turkeys. H. gallinarum infection poses a problem for the poultry industry as the nematode egg serves as a vector for the protozoan parasite, Histomonas meleagridis, the causative agent of histomonosis. The only means of detecting H. gallinarum in the environment is microscopic identification of the eggs in soil or feces; however, H. gallinarum eggs are often mistaken for those of Ascaridia galli. Three primer sets were designed from sequences cloned from the H. gallinarum genome to develop a diagnostic PCR. Each of these primer sets amplified a single product from H. gallinarum, but were unable to amplify DNA from H. meleagridis, Ascaridia galli, or Cestode sp. H. gallinarum DNA was amplified from Lumbricus sp. (earthworms) and Alphitobius diaperinus (darkling beetles), confirming that the earthworm acts as a paratenic host for H. gallinarum and suggesting that the darkling beetle may be a carrier for this nematode.

First report on trichomonads from true bugs

Although the hindgut of some insects represents a rich source of intestinal trichomonads, their diversity is only poorly understood. The aim of the present study was to investigate the presence and abundance of intestinal trichomonads in true bugs (Heteroptera). We microscopically examined intestinal contents of more than 780 specimens belonging to 28 families of true bugs from localities in China, Ghana and Papua New Guinea for the presence of intestinal endosymbionts. More than 120 samples were examined also by means of PCR using trichomonad-specific primers. We determined sequences of SSU rDNA and ITS region of two isolates of the genus Simplicimonas Cepicka, Hampl et Kulda, 2010 and one isolate of Monocercomonas colubrorum (Hammerschmidt, 1844). Although our results showed that trichomonads are very rare inhabitants of the intestine of true bugs, two of three isolated flagellates belong to species specific for reptiles. The possibility of transmission of trichomonads between reptiles and true bugs is discussed.

Emerging infectious disease leads to rapid population declines of common British birds

Emerging infectious diseases are increasingly cited as threats to wildlife, livestock and humans alike. They can threaten geographically isolated or critically endangered wildlife populations; however, relatively few studies have clearly demonstrated the extent to which emerging diseases can impact populations of common wildlife species. Here, we report the impact of an emerging protozoal disease on British populations of greenfinch Carduelis chloris and chaffinch Fringilla coelebs, two of the most common birds in Britain. Morphological and molecular analyses showed this to be due to Trichomonas gallinae. Trichomonosis emerged as a novel fatal disease of finches in Britain in 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations in 2006. By 2007, breeding populations of greenfinches and chaffinches in the geographic region of highest disease incidence had decreased by 35% and 21% respectively, representing mortality in excess of half a million birds. In contrast, declines were less pronounced or absent in these species in regions where the disease was found in intermediate or low incidence. Also, populations of dunnock Prunella modularis, which similarly feeds in gardens, but in which T. gallinae was rarely recorded, did not decline. This is the first trichomonosis epidemic reported in the scientific literature to negatively impact populations of free-ranging non-columbiform species, and such levels of mortality and decline due to an emerging infectious disease are unprecedented in British wild bird populations. This disease emergence event demonstrates the potential for a protozoan parasite to jump avian host taxonomic groups with dramatic effect over a short time period.

Infectivity ofHistomonas meleagridisin ducks

The susceptibility of mule and muscovy ducks to "blackhead" disease caused by Histomonas meleagridis was studied, using an experimental intracloacal inoculation. Turkeys were used as controls. Morbidity, mortality and body weight gain were recorded regularly during the experiments. A direct examination of the caecal content was made to determine the absence or presence of the parasite. Gross and microscopic lesions were observed on days 7, 14, 21, 28 and 35 post infection to evaluate any clinical histomoniosis in ducks and to appraise the histomonad's carriage. A scoring system was developed both for gross and histological lesions of the caecum and liver. Infected mule and muscovy ducks (n = 83) never developed any clinical signs of histomoniasis. Weight gains of infected mule and muscovy ducks were similar to those of uninfected ducks. In 67% of the ducks (56/83), it was possible to demonstrate the parasite in the caecal content throughout the experiment. Typical macroscopic caecal lesions were observed in five of the ducks between days 7 and 21 post infection, with a caecal necropsy main lesion score (MLS = 1.6) less severe than that in turkeys (MLS = 2.9). Only caecal histological lesions occurred in six of the cases. Therefore, ducks do not seem to be a susceptible host for "blackhead" but may act as carrier animals for H. meleagridis. The virulence was apparently not changed, since 67% of turkeys (10/15) infected with the caecal content of positive ducks displayed classical signs of blackhead disease. Even if H. meleagridis alone does not represent a substantial danger in the duck production, its infectivity should to be taken into account in the transmission to more susceptible species.

Cryopreservation of protozoan parasites

Conventional methods for the propagation and preservation of parasites in vivo or in vitro have some limitations, including the need for labor, initial isolation and loss of strains, bacterial, and fungal contamination, and changes in the original biological and metabolic characteristics. All these disadvantages are considerably reduced by cryopreservation. In this study, we examined the effects of various freezing conditions on the survival of several protozoan parasites after cryopreservation. The viability of Entamoeba histolytica was improved by seeding (p < 0.05, chi2 test), while this was not so effective for Trichomonas vaginalis. Of six cryoprotectants examined, dimethyl sulfoxide (Me(2)SO), and glycerol showed the strongest cryoprotective effects. The optimum conditions for using Me(2)SO were a concentration of 10% with no equilibration, and those for glycerol were a concentration of 15% with equilibration for 2h. The optimum cooling rate depended on the parasite species. Trypanosoma brucei gambiense and Leishmania amazonensis were successfully cryopreserved over a wide range of cooling rates, whereas the survival rates of E. histolytica, T. vaginalis, Pentatrichomonas hominis, and Blastocystis hominis were remarkably decreased when frozen at improper rates. Unlike the cooling rate, exposure of the protozoans to a rapid thawing method produced better motility for all parasites.

Harold Kirby's symbionts of termites: karyomastigont reproduction and calonymphid taxonomy

Harold Kirby's brilliant principle of mastigont multiplicity is published here posthumously more than 40 years after it was written. He applies this principle to large multinucleate protist symbionts of termites in establishing the taxonomy of Calonymphids (Family Calonymphidae in Phylum Zoomastigina, Kingdom Protoctista). The nuclei and kinetosomes in these heterotrophic cells are organized into trichomonad-style mastigont units which reproduce independently of cytokinesis to generate nine new Calonympha and nineteen new Stephanonympha species. The total of six genera (Calonympha, Coronympha, Diplonympha, Metacoronympha, Snyderella and Stephanonympha, all symbionts of dry-wood-eating termites, Kalotermitidae) are recognized. With the aid of Michael Yamin, the distribution of all twenty-eight of Kirby's Calonympha and Stephanonympha species are tabulated. In italic type I have annotated this paper to be comprehensible to a wide readership of cell biologists, protistologists and those interested in insect symbionts. Although this extremely original and careful work was not finished when Kirby died suddenly in 1952, I deemed it important and complete enough to finally publish it so that it would not be lost to scientific posterity.