Coordinated flagellar and ciliary beating in the protozoon Tritrichomonas foetus

Tritrichomonas foetus is a flagellated protozoon found in urogenital tract of cattle. Its free movement in liquid medium is powered by the coordinated movement of three flagella projecting towards the anterior region of the cell, and one recurrent flagellum that forms a junction with the cell body and ends as a free projection in the posterior region of the cell. We have used video microscopy and digital image processing to analyze the relationships between the movements of these flagella. The anterior flagella beat in a ciliary type pattern displaying effective and recovery strokes, while the recurrent flagellum beats in a typical flagellar wave form. One of the three anterior flagella has a distinctive pattern of beating. It beats straight in its forward direction as opposed to the ample beats performed by the others. Frequency measurements obtained from cells swimming in a viscous medium shows that the beating frequency of the recurrent flagellum is approximate twice the frequency for the three anterior flagella. We also observed that the costa and the axostyle do not show any active motion. On the contrary, they form a cytoskeletal base for the anchoring and orientation of the flagella.

Host movement and the genetic structure of populations of parasitic nematodes

Mitochondrial DNA (mtDNA) sequence data were used to compare the population genetic structures of five species of parasitic nematodes from three different hosts: Ostertagia ostertagi and Haemonchus placei from cattle, H. contortus and Teladorsagia circumcincta from sheep, and Mazamastrongylus odocoilei from white-tailed deer. The parasites of sheep and cattle showed a pattern consistent with high gene flow among populations. The parasite of deer showed a pattern of substantial population subdivision and isolation by distance. It appears that host movement is an important determinant of population genetic structure in these nematodes. High gene flow in the parasites of livestock also indicates great opportunity for the spread of rare alleles that confer resistance to anthelmintic drugs. All species, including the parasite of deer, had unusually high within-population diversities (averages of 0.019-0.027 substitutions per site between pairs of individuals from the same population). Large effective population sizes (Ne), perhaps in combination with rapid mtDNA evolution, appear to be the most likely explanation for these high within-population diversities.

[Cryptosporidia and other endoparasites in heifers imported into the Czech Republic]

Totally 887 heifers of Holstein-Friesian breed mostly in late pregnancy imported to the Czech Republic from France (597), Germany (89), Denmark (181) and Holland (20) were examined coprologically from September 1993 to March 1995 in the parasitological laboratory of the National Veterinary Institute (NVI). Prague. Feces were sampled individually, rectally, always on days 1-3 following importation from heifers housed in particular quarantine sheds. In compliance with presently valid veterinary regulations, all animals were examined for liver fluke disease (fascioliasis) and lungworm. Moreover, 634 heifers were submitted to qualitative coprological examination aimed at revealing the presence of cysts and oocysts of protozoa, eggs of taenias and nematodes of gastrointestinal tract. The method according to Pavlásek (1991), especially designed for proving oocysts of the genus Cryptosporidium, was applied in all fecal specimens delivered to the SVI from animals in quarantine (N = 887). From trematodes, 12 heifers imported from France were positive for eggs of Fasciola hepatica and in other two animals eggs of the genus Paramphistomum were found. None of the imported heifers showed lungworm disease. Summary of data on occurrence of endoparasites gained during qualitative examination of samples of feces taken from heifers imported from France, Germany and Denmark is presented in Tab. I. Parasitologically, 91.2 to 100% of imported animals were positive. Taeniasis (the genus Moniezia) was detected in 2.8% of heifers imported from France and in 9.8% animals from Denmark. Protozoal parasites were found in 58.8% (Denmark) and 92.8% (Germany) heifers. Coccidial oocysts most frequently observed represented the genus Eimeria (E. bovis, E. auburnensis and E. zuernii). Gastrointestinal nematodes of nine genera were found in 72.5 to 80.8% of heifers. The most frequent findings were genera Ostertagia, Haemonchus and Trichostrongylus. Oocysts, morphologically identical with Cryptosporidium muris Tyzzer (1907), 1910, were detected in 4.5% of heifers imported into the Czech Republic from France and in 7.9% of those from Germany. In view of the fact the imported heifers were sampled always on days 1-3 of their quarantine following their importation it is quite impossible, considering the development of the protozoon, they could become infected just in the territory of the Czech Republic. Therefore, with the highest probability, our findings of C. muris-like oocysts in heifers are of priority importance for France and Germany because in the literature these countries do not report cattle as a host of this protozoon. We have found out 57.9% out of 19 animals positive for C. muris on one farm of a private cattle keeper. On the basis of a long-term monitoring of three dairy cows and one bull, the duration of the patent period is longer than 18 months, while we do not know precise onset of shedding oocysts of the protozoon in these naturally infected animals. Furthermore, the paper discusses the need of future studies of C. muris from the point of view of spread, pathogenicity, specificity and host spectrum. The author proposes and recommends obligatory examinations of imported animals with special attention paid to presence of coccidia of the genus Cryptosporidium in order to maintain, with respect to their zoonotic character, these protozoal infections under proper control. At present the parasitological laboratory of the NVI in Prague has a bank of oocyst isolates of the C. muris type from cattle (Bos taurus), from desert hamsters (Phodopus roborovskii Satunin, 1903) and camels (Camelus bactrianus). Experimental infections is permanently kept in laboratory mice following successful transmission from desert hamsters.

Successful application of deltamethrin pour on to cattle in a campaign against tsetse flies (Glossina spp.) in the pastoral zone of Samorogouan, Burkina Faso

1,500-2,000 head of cattle were treated with deltamethrin 1% Spot On in an area of high tsetse densities, notably of Glossina morsitans submorsitans. After four treatments at monthly intervals, the time between two treatments was increased to two months. 11 months after the commencement of the campaign the fly population had decreased from initially 54.2 flies/trap/day to densities varying between 0.06-2.0 flies/trap/day, mostly G. palpalis gambiensis. Blood-meal analysis showed that this species was surviving in limited areas, mainly feeding on monitor lizards; consequently it is unlikely that this species can be eradicated solely by the use of cattle treated with a pyrethroid. The resistance of Trypanosoma congolense to all commercially available trypanocides necessitated the epidemiological monitoring of calves which were born after the start of the campaign in order to reasses the real challenge. The risk of new infections was low, basically due to contracts between the cattle and tsetse outside the ranching area. A weight increase from 122.3 kg to 213.6 kg of calves aged 6-12 months was recorded from October 1993 to October 1994. An average daily weight gain of more than 400 g was observed from the end of April 1994 to the beginning of August 1994.

[The topographic selectivity of the landing and feeding by sucking of gadflies (Diptera: Tabanidae) in attacking cattle]

The detailed maps of the distribution of sittings and feedings of the 12 tabanid species among 22 zones of a cow's body are given. The material on the observations of individually marked tabanids attacking a single cow in conditions of the Pskov region in 1984-1990 (Konstantinov, 1992) has been used in present paper. It is established, that the distribution of sittings and feedings onto the cow's body has a species-specific character. The 12 species were arranged into 5 groups based on characters of the topographical similarity of their distributions. The distribution of feedings has the less range than the distribution of sittings within each species. The distribution of sittings and feedings within each species coincide average by 60%. The effectiveness of tabanid's sittings is different within different zones of the cow's body.

Comparison of characteristics of life cycle in female ticks collected on N'Dama and zebu cattle

Characteristics of the life cycle of female ticks (Amblyomma variegatum, Hyalomma truncatum and Boophilus geigyi) fed on N'Dama and zebu cattle were studied in the laboratory from pre-oviposition period to larval development. Percentage of A. variegatum eggs hatched and engorgement weight of H. truncatum were lower in ticks collected on N'Dama than on zebu cattle. Laboratory results confirmed field observations of species specific tick resistance in the N'Dama breed.

Persistence of Tritrichomonas foetus in naturally infected cows and heifers in Argentina

Tritrichomonas foetus infection was investigated in 76 pregnant and 64 non-pregnant cows slaughtered in the local abbattoir and in two different lots of first-service heifers that were found to be non-pregnant 60 days post breeding (PB). In live and slaughtered animals, mucus samples were obtained from the vagina and from the vagina and uterus, respectively, using a "screw-head scraper rod". In pregnant cows, samples of amniotic and allantoid fluid were also collected, as well as samples from the stomach contents of the fetuses. All samples were cultured in Modified Plastridge Medium. T. foetus was isolated from three pregnant and two non-pregnant slaughtered cows. Parasites were recovered from the vagina of these five cows, as well as from the uterus in two cases and from the fetus in one case. Lot I of first-service heifers consisted of 323 females from eight different farms. Bulls infected with T. foetus from these farms were culled or treated, and heifers found empty at diagnosis of pregnancy were culled. Lot II consisted of 120 heifers from a single farm where T. foetus was controlled only in bulls. All heifers from Lot I were T. foetus negative. In Lot II, 12 of 120 heifers (10%) were T. foetus positive. In ten of these the parasites were observed once, in one at 60 days PB, in seven at 160 days PB and in two at 240 days PB; in the remaining two infected heifers, an irregular pattern of isolation persisted during 300 days PB. On the basis of these results, control methods are discussed and analysed.

Temperature and population density effects on feeding activity of Stomoxys calcitrans (Diptera: Muscidae) on cattle

The relationship of population density and temperature to feeding activity of stable flies, Stomoxys calcitrans (L.), on cattle was studied by placing cattle in constant temperature chambers with controlled fly density and temperature. The number of flies per front leg declined within hours after release but increased with fly density and temperature. The time flies spent on the host during a 5.5-h exposure period ranged from < 2.5 min at temperature < 16 degrees C to > 34 min when temperature was > 20 degrees C. Estimates of the temperature threshold for flight ranged from 10.7 to 20.1 degrees C and were influenced by density and time after release. Nearly 45% of the feeding flies were on the front legs, and this proportion was unaffected by density, temperature, and time after release. In the field, the number of flies per foreleg also was influenced by density and temperature. Estimated flight threshold was 10.7 degrees C, low enough to allow flight during 41-95% of the daylight hours from May through October in southern Alberta.

Anthelmintic sales in the highveld region of Eastern Transvaal

Throughout a survey from 1991 to 1993 in the Highveld region of Eastern Transvaal, levamisole sales dominated in the sheep anthelmintic market. The macrocyclic lactone sales dominated in the cattle anthelmintic market, but were superseded by those of levamisole in 1993. The salicylanilides enjoyed the second highest demand in the sheep anthelmintic market. Anthelmintics were purchased throughout the year, but sales peaked in summer and autumn. When it rained in winter, sales increased during winter and peaked in spring. Eastern Transvaal Co-operative (OTK) sold 2,64 therapeutic doses per sheep during the driest year and 3,54 per sheep during the wettest year in the Highveld region. Only 24-29% of the cattle in the region could be treated with the anthelmintics sold by OTK for cattle. Total sales are estimated at double these figures.

In vitro cultivation of a Babesia sp. from cattle in South Africa

A South African Babesia sp. of cattle which is as yet unclassified, was continuously cultivated in micro-aerophilous stationary-phase culture. The parasites were resuscitated from a blood stabilate stored in liquid nitrogen. A modified HL-1 medium supplemented with either horse or bovine serum was used. Cultures were initiated in a humidified atmosphere containing 2% O2, 5% CO2 and 93% N2 at 37 degrees C. Parasites were detected on Giemsa-stained smears after 2 d in culture. On day 4, the cultures were split at a ratio of 1:2 (v/v) and transferred into a humidified atmosphere of 5% CO2 in air. Starting from day 6, subcultures were made daily at a ratio of 1:4 (v/v). The percentage of parasitized erythrocytes ranged from 2-5%. Addition of purine bases (hypoxanthine, adenine, adenosine or guanosine) was essential for the continuous propagation of the parasites when bovine, but not horse serum, was used for medium supplementation.

A novel method for the administration of metacercariae of Fasciola hepatica to adult cattle

A gelatin bolus containing the infective stage of Fasciola hepatica was prepared and administered to adult cattle. The bolus was formed to fit into the nozzle of a standard size bolus-type dosing gun. Administration proved easy and effective causing minimal stress to the animal, yet ensuring that experimental infection took place.

Comparative RAPD-PCR analysis of lungworms (Dictyocaulidae) from fallow deer, cattle, sheep, and horses

Genomic DNA isolated from the four Dictyocaulus species D. viviparus, D. eckerti, D. filaria and D. arnfieldi was compared by random amplified polymorphic DNA polymerase chain reaction (RAPD)-PCR to get additional information whether lungworms from fallow deer belong to a separate species (D. eckerti) or have to be regarded as an isolate of D. viviparus in wild ruminants. The resulting banding patterns of the electrophoresed PCR products were compared to assess the degree of genetic differences between the different lungworms. For the two D. viviparus isolates a similarity coefficient of 93.4% was calculated, whereas the similarity coefficient of D. viviparus, D. eckerti, D. filaria and D. arnfieldi ranged from 12% to 32%. The similarity coefficient of 32% between D. eckerti and D. viviparus compared with the intraspecies similarity of 93.4% indicates that D. eckerti most likely belongs to a separate species and is not a D. viviparus isolate of wild ruminants.

[Blastocystis fauna]

On the area of former USSR and Russia 10 species of Blastocystis were described: Blastocystis lessonae from Rana lessonae, B. anatis from Anas platyrhynchos, B. anseri from Anser anser, B. galli from Gallus gallus, B. numidae from Numida meleagris, B. meleagridis from Meleagris gallopavo, B. equi from Equus coballus, B. suis from Sus scrofa, B. bovis from Bos taurus, B. ovis from Ovis aries.

An epidemiological study of Cryptosporidium parvum in two herds of adult beef cattle

Prevalences of Cryptosporidium parvum oocysts in faeces and of isotype-specific anti-C. parvum antibodies in serum of apparently healthy adult cattle on two farms were determined. On Farm 1 cryptosporidial diarrhoea had been recorded in more than 80% of calves born over the previous 5 years, whereas on Farm 2 cryptosporidiosis had never been reported. No differences were demonstrated in oocyst excretion or presence of antibodies between the two farms. C. parvum oocysts were detected in 62.4% of faecal smears collected from a total of 553 apparently healthy adult cattle. Sucrose flotation was performed on a proportion of the faecal samples. This proved a more sensitive technique, detecting oocysts in 92% of the samples tested, and highlighting the insensitivity of direct smears for detecting oocysts. More than 90% of the cattle had specific anti-C. parvum IgG, IgG1, IgG2 and IgM antibodies and 58% specific anti-C. parvum IgA antibodies. Results suggest that asymptomatic adults may play an important role in the epidemiology of cryptosporidiosis in calves.

Recent acquisitions on tick and tick-borne disease resistance in N'dama (Bos taurus) and Gobra zebu (Bos indicus) cattle

The use of disease resistant breeds is recognised as an economically realistic alternative to acaricide application and drug administration in tick and tick-borne disease control schemes. Although resistance is mainly associated with zebu (Bos indicus) breeds, studies carried out in The Gambia show a higher resistance to ticks and tick-borne diseases in N'dama (Bos taurus) than in Gobra (B. indicus) cattle. Tick resistance in N'dama breed appears to be effective against those species with long hypostome, such as Amblyomma variegatum and Hyalomma spp. The possible mechanisms involved are discussed. Further investigations are identified to assess the economic value of tick and tick-borne disease resistance in the N'dama breed.

A genetic analysis of mixed population in Theileria sergenti stocks and isolates using allele-specific polymerase chain reaction

In order to differentiate parasite populations bearing two allelic forms of p33/32, an immunodominant piroplasm surface protein of Theileria sergenti, two sets of oligonucleotide primers were designed to amplify either of the two allele by the polymerase chain reaction (PCR). Each set of the primers differentially amplified either of Ikeda- or Chitose-type p33/32 genes. By using this allele-specific PCR and restriction enzyme digestion of amplified products, parasite populations within field isolates collected from different geographical regions in Japan were analyzed. Both of the allelic forms were detected in 13 samples out of 20 isolates and stocks by PCR. Either of Ikeda or Chitose type of p33/32 allele was detected in the other 7 samples. These results indicated that the majority of T. sergenti-infected calves (11/15) in Japan harbored mixed parasite populations bearing at least two different alleles of p33/32.

The spatial distribution of Borrelia burgdorferi-infected Ixodes ricinus in the Connemara region of County Galway, Ireland

Studies were carried out in the Connemara area of County Galway in the west of Ireland in order to determine the abundance and distribution of the tick, Ixodes ricinus and the prevalence of its infection with Borrelia burgdorferi. The tick was very abundant locally, in particular when associated with cattle, sheep and enclosed red deer. Large numbers of ticks not only occurred on the pastures, but also on adjacent roadside verges. No infections with B. burgdorferi could be demonstrated when nymphal ticks were sampled from central areas of the pastures, suggesting that livestock and red deer are probably not significant reservoirs of the spirochaete. Small numbers of infected nymphal and adult ticks were associated with hedges, dry stone walls, the margins of woodland adjoining infested pastures and in woodland from which livestock were excluded. Woodmice (Apodemus sylvaticus) were most numerous in such habitats and the majority were infected with B. burgdorferi.

Gangliosides as a possible receptor on the bovine erythrocytes for Theileria sergenti

To elucidate whether or not gangliosides on the bovine erythrocytes serve as a receptor for Theileria sergenti merozoites, the reactivities of the T. sergenti piroplasms with gangliosides were studied by the liposome agglutination test. The parasites reacted weakly with I-active ganglioside containing N-acetylneuraminic acid (NeuAc) and strongly with I-active ganglioside containing N-glycolylneuraminic acid (NeuGc). However, none of the other gangliosides expressed on the bovine erythrocytes, such as GM3 (NeuAc), GM3 (NeuGc), sialosylparagloboside (SPG) (NeuAc), SPG (NeuGc), i-active ganglioside (NeuAc), and i-active ganglioside (NeuGc), were recognized. After infection with T. sergenti, furthermore, the content of I-active ganglioside (NeuAc) was less (p < 0.05), and I-active ganglioside (NeuGc) content was much less in the erythrocytes (p < 0.01), though the contents of other NeuAc- and NeuGc-containing gangliosides did not so vary with T. sergenti infection. These results suggest that the parasites recognize the I-active ganglioside as their receptor and bind preferentially to NeuGc-carrying I-active ganglioside rather than to NeuAc-type in the target cell membranes, and that the reduction of the contents of I-active gangliosides (NeuAc and NeuGc) on the erythrocytes was related to T. sergenti infection.

[Anthelmintics resistance in gastrointestinal nematodes in domestic animals]

In Belgium benzimidazole resistance has been reported in 28% of the sheep farms and 29 to 50% of the studs. In several member states of the European Union the prevalence of anthelmintic resistance (AR) is even higher than in Belgium, although AR is nearly absent in some countries of Southern Europe. AR is particularly widespread in certain nematodes of sheep, goats and horses in Europe, whereas only sporadic cases of AR have been reported in helminths of cattle. In Belgium only one case of AR has been described in goat and one in cattle; no surveys for AR have been carried out in pigs. The main helminth species, in which AR has been observed, are Haemonchus contortus, Ostertagia circumcincta and Trichostrongylus spp. in small ruminants, the Cyathostominae in horses and Oesophagostomum spp. in pigs. Resistance has developed particularly against the benzimidazoles and to a lesser extent against the levamisole/morantel group. Up to now the prevalence of ivermectin resistance remains low, but the number of cases is increasing during recent years. Due to the low sensitivity of the currently used techniques for the detection of AR (egg count reduction test and in vitro egg hatch test) the available figures underestimate the prevalence of AR. Finally, possible control measures are discussed in order to avoid or to delay the development of resistance.

Experimental Trypanosoma congolense infection on naturally occurring ticks in N'dama and Gobra zebu cattle

The effects of experimental Trypanosoma congolense infection in Gambian N'dama and Gobra zebu cattle on number of naturally-occurring adult ticks attaching were studied. An indirect fluorescent antibody test was performed to detect serological prevalence of Cowdria ruminantium antibody. The intravenously imposed trypanosome infection did not result in significant (P > 0.05) differences in Amblyomma variegatum and Hyalomma spp. infestations between control and infected N'dama cattle. Control N'damas carried significantly (P < 0.001) lower numbers of A. variegatum and Hyalomma spp. than the control zebus. Serological frequency of C. ruminantium antibody was similar in both control or infected N'dama and in control or infected zebu cattle. No deaths occurred among N'dama cattle, while all six trypanosome infected zebus progressively died within nine weeks post-infection but trypanosomosis was excluded as the primary cause of death. Examined Giemsa-stained blood smears were negative for the presence of tick-borne micro-organisms. Four positive cases of cowdriosis were identified during post-mortem examination. It was concluded that N'damas, even when submitted to trypanosome infection, react consistently better than Gobra zebus to tick attachment. These results emphasize the benefits of rearing disease resistant cattle breeds, such as N'dama, in areas where risks of trypanosomosis and cowdriosis coexist.

Serum constituent profiles of beef heifers infested with horn flies (Diptera: Muscidae)

Nine yearling crossbred beef heifers, Bos taurus L., were used to examine physiological responses to horn fly, Haematobia irritans (L.), infestation. Heifers were stanchioned indoors in individual environmentally controlled rooms. On day 0, each animal received 0, 500, or 1,000 horn flies. Fly numbers were adjusted daily to maintain an appropriate infestation for each heifer. Feed intake, respiration rate, and rectal temperature was recorded daily. In addition, blood samples were collected from each animal on days 0, 12, and 33 for serum constituent analysis. To monitor metabolic hormone status, intensive blood samples were also collected hourly for 6 h on days 0, 12, and 33. Throughout the period of treatment, feed intake values were similar among treatments resulting in comparable body weight at the end of the trial. Respiration rates on each day were similar among groups. Rectal temperature was also unaffected by horn fly infestations. Serum electrolyte analysis revealed that neither Na, K, Cl, Ca, P, nor Fe differed among treatments. Likewise, HCO3/CO2 ratio, anion gap, and serum osmolality did not differ among treatment groups. Major indicators of nutrient status (glucose, cholesterol, triglycerides, urea N, creatinine, uric acid, albumin, globulin) and insulin, growth hormone, and prolactin were also unaffected. Serum bilirubin and enzyme (alkaline phosphatase, creatine phosphokinase, gamma-glutamyl transpeptidase, lactic dehydrogenase, aspartate amino transferase, alanine amino transferase) concentrations were similar in control heifers and those infested with horn flies.(ABSTRACT TRUNCATED AT 250 WORDS)

Host blood meals and chromosomal inversion polymorphism in Anopheles arabiensis in the Baringo District of Kenya

Studies were carried out in the villages of Kapkuikui and Maji-Ndege in the Loboi area of Baringo District, Kenya, to obtain baseline data on species identification of the Anopheles gambiae group, their feeding and resting behavior, and their frequencies of chromosomal inversions. This was carried out towards predicting the effect of introducing permethrin-impregnated cloths or other intervention measures. In this study, Anopheles arabiensis was identified as the only species of the An. gambiae group. This species contained 2 inversions, 2Rb and 3Ra, occurring at frequencies ranging from 55 to 60%, and from 5 to 11%, respectively. There was no evidence for nonrandom mating. Indoor- and outdoor-collected samples were significantly different in respect of inversion 3Ra in one village and in the distribution of the different sources of blood meals in both areas. In these villages, 37% of indoor-resting mosquitoes fed outside before entering houses to rest.

Ingestion of host immunoglobulin by three non-blood-feeding nematode parasites of ruminants

Host immunoglobulin was detected in homogenates of adult worms or fourth stage larvae of Haemonchus contortus, Ostertagia ostertagi, O circumcincta and Dictyocaulus viviparus, but not in preparasitic third stage larvae of H contortus. All the worms had been washed in detergent before being homogenised to remove any immunoglobulin adhering to the cuticle. This procedure, the concentrations of immunoglobulin detected and observations on sections of the worms stained with fluorescent anti-sheep immunoglobulin, all suggested that the immunoglobulin had been ingested, even by the non-blood-feeding species. This finding suggests that the Ostertagia species and D viviparus may be susceptible to vaccination by the gut antigen approach, a method with considerable promise for blood-feeding parasites like H contortus and Boophilus microplus.