Efficacy of an injectable formulation of eprinomectin against Psoroptes cuniculi, the ear mange mite in rabbits

Thirty rabbits naturally infected with ear mange mite, Psoroptes cuniculi, were subcutaneously administrated with a single dose of eprinomectin at 100, 200 and 300 microg/kg body weight or vehicle on day 0. The extent of lesions was scored on day -6 (prior to treatment), day 0 (treated), days 7, 14, 21, 28 and 35, the ear scabs were collected simultaneously; mites in scabs were examined and counted. The results showed that a single dose of eprinomectin at 200 or 300 microg/kg body weight following subcutaneous administration was able to eliminate P. cuniculi infection in rabbits, and a dose of eprinomectin at 100 microg/kg could significantly reduce mites but was unable to eliminate P. cuniculi.

[Gastrointestinal parasites of rabbits in coproscopic investigations]

BACKGROUND

Parasitological screening was carried out in a breeding herd of the New Zealand White rabbit breed in 2004.

MATERIAL AND METHODS

Mothers, together with their offsprings, were kept in boxes on deep litter, whereas young rabbits were transferred to cages with slatted floor. All the animals were fed a complete balanced pelleted feed with two coccidiostats added alternately (Lerbec, Robenidine), and droplet watering system was applied. No anthelmintic was used in the rabbitry. A total of 170 individual samples of fresh feces from females of breeding stock, and 55 pooled samples in the case of young animals 2-4 months of age, collected on a month intervals, were analyzed according to a modified concentration McMaster's method, using saturated salty water with sugar as a flotation fluid.

RESULTS

The presence of several species of coccidia was evaluated, with Eimeria stiedae, E. perforans, E. media and E. magna being found in great numbers. The dynamics of infection showed that both adults and young animals were affected by coccidia mostly in May (mean intensity reached at that time 24000 opg in young rabbits), and then until August the infection lasted on a high level. As regards coccidiosis, parasitism could be considerably cut back in the herd by frequent changing of the straw litter, which should also always be dry. Only Passalurus ambiguus was found from nematodes, and only in the feces of adults, probably due to the modern forage and watering system applied, which broke the other worms' life cycles.

Tick infestations of the eastern cottontail rabbit (Sylvilagus floridanus) and small rodentia in northwest Alabama and implications for disease transmission

Studies were conducted over a four-county area of northwest Alabama to determine the association of eastern cottontail rabbits with Dermacentor variabilis, the eastern United States vector of Rocky Mountain spotted fever. A secondary objective was to compare infestations of this tick on rabbits with infestations on commonly encountered rodent species as a means of determining the relative importance of each in the disease transmission cycle. These epidemiologic surveys were conducted in response to reported fatal cases of Rocky Mountain Spotted Fever in two counties of the study area. From 202 eastern cottontail rabbits, 3,956 ticks were collected. Of this total, 79.87% were Haemphysalis leporispalustris, 9.15% Amblyomma americanum, 8.22% Ixodes dentatus, and 2.76% D. variabilis. Only immature stages of D. variabilis were collected from cottontail rabbits. Ticks were collected on rabbits in all months except November, and only one specimen was taken in January. Based on the average number of ticks per host collected in each month, April was the peak month for D. variabilis and I. dentatus. High values for H. leporispalustris also occurred at this time, but even higher values occurred in October and December. The heaviest infestation of A. americanum occurred during the month ofAugust and coincides with the activity period for the larvae of this species. Two hundred sixty-nine of the smaller Rodentia, comprising 13 species, yielded 264 ticks, all D. variabilis, and all but two were immature stages. Five rodent species, Microtus ochragaster Orozomys palustris, Peromyscus gossypinus, Peromyscus leucopus, and Sigmodon hispidus accounted for 95.83% of the ticks collected, and appeared to be preferred hosts for D. variabilis; all five had higher infestation levels per host than did the eastern cottontail rabbit. Data on host relationships in association with seasonal activity are presented.

The role of rabbits in the biology of some gastrointestinal parasites infecting sheep

Twelve rabbits (Buscat strain) were classified into 4 Gs (3 rabbits each). The first three groups were experimentally infected with the infective 3rd stage larvae of Bunostomum phlebotomum, Trichostrangylus colubriformis and Cooperia onchophora, respectively. The 4th G was used as a control. The faecal examination until slaughtering time (21 days post infection) of all Gs did not show any nematode eggs. The microscopic examination of the gastrointestinal canal contents and mucosal scrapings of all Gs at slaughtering time did not show any gastrointestinal parasites. The 4th stage larvae (L4) of B. phlebotomum and T. colubriformis were obtained after digestion of epithelium of ileum and duodenum of G.1 & G.2 respectively. The histopathologic examination of gastrointestinal canal, ileum of G.1 showed necrosis of epithelium and eosinophilic infiltration associated with parasitic stages (L4) of B. phlebotomum. The intestine of G.2 showed parasitic stages (L4) loaded in the villi of duodenum associated with eosinophilic infiltration of T. colubriformis. The intestine of G.3 showed necrosis of the villi and eosinophilic infiltration due to C. onchophora. The histopathologic examination of the gastrointestinal canal of control group was normal.

Temporal host-parasite relationships of the wild rabbit, Oryctolagus cuniculus (L.) as revealed by stable isotope analyses

Natural abundances of the stable isotopes, 15N/14N (delta15N) and 13C/12C (delta13C), were used to study temporal host-parasite relationships of the wild rabbit, Oryctolagus cuniculus (L.). During the 12-month sampling period, temporal isotopic shifts in delta15N were noted for dietary vegetation, host rabbit faeces and fur, but not for muscle or stomach contents. delta15N varied temporally for the parasitic cestode species, Mosgovoyia pectinata but not for Cittotaenia denticulata. Similarly, intestinal parasitic nematodes had apparent species-specific delta15N patterns. Only rabbit fur and intestinal parasitic nematodes did not exhibit temporal shifts in delta13C. Overall, host faeces and stomach contents were isotopically indistinct as a likely consequence of coprophagy. Relative to their host, parasitic nematodes were 15N-enriched, consistent with an increase in trophic level status. Conversely, cestodes were 15N-depleted. Isotopically, each parasite reflected a species-specific relationship with their rabbit host. This technique could be utilized to integrate parasites into food-web studies.

In vitro cultivation of a zoonotic Babesia sp. isolated from eastern cottontail rabbits (Sylvilagus floridanus) on Nantucket Island, Massachusetts

A Babesia sp. found in eastern cottontail rabbits (Sylvilagus floridanus) on Nantucket Island, Massachusetts, is the same organism that caused human babesiosis in Missouri and Kentucky, on the basis of morphology and identical small-subunit rRNA (SSU rRNA) gene sequences. Continuous cultures of the rabbit parasite were established from infected blood samples collected from two cottontail rabbits livetrapped on Nantucket Island. HL-1 medium or minimal essential medium alpha medium supplemented with 20% human serum best supported in vitro propagation of the parasite in human or cottontail erythrocytes, respectively. Parasite growth was not sustained in domestic-rabbit erythrocytes or in medium supplemented with domestic-rabbit serum. The cultured parasites were morphologically indistinguishable from the Kentucky human isolate. Transmission electron microscopy revealed similar fine structures of the parasite regardless of the host erythrocyte utilized in the cultures. Two continuous lines of the zoonotic Babesia sp. were established and confirmed to share identical SSU rRNA gene sequences with each other and with the Missouri and Kentucky human Babesia isolates.

The inadvertent introduction into Australia of Trypanosoma nabiasi, the trypanosome of the European rabbit (Oryctolagus cuniculus), and its potential for biocontrol

Wild rabbits (Oryctolagus cuniculus) in Australia are the descendents of 24 animals from England released in 1859. We surveyed rabbits and rabbit fleas (Spilopsyllus cuniculi) in Australia for the presence of trypanosomes using parasitological and PCR-based methods. Trypanosomes were detected in blood from the European rabbits by microscopy, and PCR using trypanosome-specific small subunit ribosomal RNA (SSU rRNA) gene primers and those in rabbit fleas by PCR. This is the first record of trypanosomes from rabbits in Australia. We identified these Australian rabbit trypanosomes as Trypanosoma nabiasi, the trypanosome of the European rabbit, by comparison of morphology and SSU rRNA gene sequences of Australian and European rabbit trypanosomes. Phylogenetic analysis places T. nabiasi in a clade with rodent trypanosomes in the subgenus Herpetosoma and their common link appears to be transmission by fleas. Despite the strict host specificity of trypanosomes in this clade, phylogenies presented here suggest that they have not strictly cospeciated with their vertebrate hosts. We suggest that T. nabiasi was inadvertently introduced into Australia in the 1960s in its flea vector Spilopsyllus cuniculi, which was deliberately introduced as a potential vector of the myxoma virus. In view of the environmental and economic damage caused by rabbits in Australia and other islands, the development of a virulent or genetically modified T. nabiasi should be considered to control rabbits.

Protective effect of Eimeria stiedae coproantigen against hepatic coccidiosis in rabbits

Immunization of rabbits against hepatic coccidiosis was tried. The animals were immunized twice with Eimeria stiedae coproantigen in freund's adjuvant with two week intervals. The rabbits were challenged orally with sporulated E. stiedae oocysts one week post last injection. The protection was assessed by number of oocysts output, number of focal liver lesions, clinical sings and antibody response. The immunization resulted in 70% protection from infection and decline in oocysts count. High level of IgG response in immunized rabbits than control infected ones was occurred and being responsible for the recorded protection. The electrophoretic make up of the coproantigen and oocyst antigen showed different patterns of separation. Common as well as specific bands to each antigen were identified. Using the rabbit sera after 3 weeks post vaccination in immunoblot assay, immunogenic components were detected of molecular weight 155, 103, 74, 66, 44, 22KD with coproantigen and 155, 115, 57, 26 KD with oocyst antigen. While, the rabbit sera after 2 and 4 weeks post challenge reacted with oocyts antigen, in immunoblot assay, revealing immunogenic bands of molecular weight 155, 115, 57, 26, 22KD and 155, 115, 57, 25 KD respectively. Bands of 22KD and 155KD are partially responsible for eliciting host protective immune response where they were recognized by immunized sera in coproantigen and by immunized infected sera in oocyst antigen.

FURTHER OBSERVATIONS ON THE DEVELOPMENT OF GONGYLONEMA PULCHRUM IN RABBITS

Third-stage larvae of Gongylonema pulchrum from naturally infected dung beetles were inoculated orally into 24 rabbits. Worm recovery ranged from 54 to 91% (mean = 67.5%) during the period from 24 hr to 52 wk postinoculation (PI). Two hours PI, the larvae entered the mucosa at the junction of the stomach and esophagus and migrated upward. Early development occurred primarily in pharyngeal mucosa, tongue, and buccal mucosa. The third molt took place 11 days PI and the final molt at 36 days PI. Male worms reached sexual maturity at 7 wk PI and females at 9 wk PI. Adult worms were found mainly in the esophagus but also occurred in the tongue and the wall of the oral cavity after 30 wk PI. Embryonated eggs appeared in the feces of 3 rabbits inoculated with 50 or 100 larvae on days 72-81 PI. Morphologically, the cuticle in young fourth-stage larvae exhibited bosses on the anterior portion on day 11 PI, and the left spicule length : total body length exhibited no remarkable change between 9 and 52 wk PI. The latter finding confirms the utility of the ratio for identification of the nematode.

Concentration of some toxic elements in Oryctolagus cuniculus and in its intestinal cestode Mosgovoyia ctenoides, in Dunas de Mira (Portugal)

The need for sentinel organisms reflecting small-scale changes in heavy metal pollution of different habitats has been previously stated and the role of terrestrial mammalian parasites has been pointed out as an important field of research aiming at the potential use of parasitic models as bioindicators. The scope of the present study was to assess the concentration of some toxic (Cd, Pb, As and Hg) elements in Dunas de Mira (Natura 2000 PTCON055) while testing the model constituted by the wild rabbit (Oryctolagus cuniculus Linnaeus, 1758) and its intestinal cestode parasite Mosgovoyia ctenoides Railliet, 1890 as potential bioindicators. Wild rabbits were harvested by hunters and analysed for intestinal cestodes. Samples of kidney, liver, intestinal mucosa, muscle of host and also M. ctenoides were taken and deep-frozen for posterior element analysis by ICP-MS. In general, levels of contamination in rabbit tissues were found to be low although some of the elements were detected in higher quantities when compared to other previous reports for wildlife in Europe. The highest quantity of Pb was found in rabbit muscle (3.81 ppm) while highest Cd and Hg values were found in kidney (1.02 and 0.08 ppm). Significant linear relationships were found between Pb concentration in the parasite and Pb concentration in kidney (P=0.0047), muscle (P=0.0002) and intestinal mucosa (P=0.0181) and between As concentration in the parasite and As concentration in liver (P=0.0024), kidney (P=0.0010), muscle (P=0.0003) and intestinal mucosa (P=0.0047). The most significant relationships for Pb and As were detected between element concentration in the cestode and in host muscle. However, maximum Pb and As concentrations in M. ctenoides were only twice as high as those found for rabbit kidney and therefore it is not possible to confirm the role of the model O. cuniculus/M. ctenoides as a promising bioindicator system unlike other mammalian host/cestode models tested in other studies. The contrasting results might be due to differences in the absorption processes in the tegument of different cestode families. Furthermore, the large size of the cestodes used in the present study might also explain the relatively low element concentration values obtained.

Peak shift and epidemiology in a seasonal host-nematode system

Insight into the dynamics of parasite-host relationships of higher vertebrates requires an understanding of two important features: the nature of transmission and the development of acquired immunity in the host. A dominant hypothesis proposes that acquired immunity develops with the cumulative exposure to infection, and consequently predicts a negative relationship between peak intensity of infection and host age at this peak. Although previous studies have found evidence to support this hypothesis through between-population comparisons, these results are confounded by spatial effects. In this study, we examined the dynamics of infection of the nematode Trichostrongylus retortaeformis within a natural population of rabbits sampled monthly for 26 years. The rabbit age structure was reconstructed using body mass as a proxy for age, and the host age-parasite intensity relationship was examined for each rabbit cohort born from February to August. The age-intensity curves exhibited a typical concave shape, and a significant negative relationship was found between peak intensity of infection and host age at this peak. Adult females showed a distinct periparturient rise in T. retortaeformis infection, with higher intensities in breeding adult females than adult males and non-breeding females. These findings are consistent with the hypothesis of an acquired immune response of the host to a parasite infection, supporting the principle that acquired immunity can be modelled using the cumulative exposure to infection. These findings also show that seasonality can be an important driver of host-parasite interactions.

Parasite-mediated reduction in fecundity of mountain hares

Mountain hare populations in Scotland exhibit regular 10 year fluctuations in abundance. Simple models of host-parasite population dynamics suggest that parasite-mediated reductions in host fecundity can cause a transition from stable to cyclic host population dynamics. We tested the hypothesis that parasites reduce hare fecundity by experimentally reducing parasite burdens and recording female survival, body condition and fecundity. We captured 41 adult female hares in October 2002; 22 were treated with Ivermectin to remove parasites and 19 were left untreated as controls. The treated and untreated hares were culled in May 2003 together with a second control group of nine unhandled hares. Treatment with Ivermectin significantly reduced the abundance of Trichostrongylus retortaeformis and increased-the fecundity of the hares, but had no measurable effect on body condition or over-winter survival. These results are consistent with the hypothesis that parasites may be a contributory cause of cycles in populations of mountain hares.

Induction of protective antibody response in rabbits against fascioliasis with Toxocara/Fasciola cross- reactive defined antigen

A method of affinity chromatography purification of Toxocara vitulorum antigen cross- reacts with Fasciola gigantica antiserum is described. Characterization of the isolated cross- reactive fraction by SDS-polyacrylamide gel electrophoresis, isoelectric focusing and amino acid analysis resulted in a fraction consists of five polypeptides of 137.7KDa, 81KDa, 75KDa, 48KDa and 21.6KDa with isoelectric points of 8, 7.5, 7.2, 6.7 and 6.6. Seventeen amino acids were identified in the fraction with high proportions of only two of them (tyrosine and glutamic). Rabbits immunization with this identified T. vitulorum cross- reactive antigen in Freund's adjuvant followed by challenge with F. gigantica metacercariae resulted in 60% reduction in worm burden over control infected rabbits. Higher IgG level was detected in vaccinated rabbits four weeks post first immunization than control infected ones and remained high up to the end of the trial.

Cross-reactivity between antigens from Amblyomma cajennense and A. hebraeum (Acari: Ixodidae)

Laboratory animals exposed to feeding ticks develop resistance which is reflected by a decline in tick engorgement weight, egg-laying by adults and reduced egg viability. Serum antibodies from these hosts and their reaction with tick antigens have been detected by different methods, including precipitation techniques, immunofluorescent techniques, ELISA and Western blots. However, little is known about the effects of antibodies on ticks that engorge on resistant hosts, or which tissues of the tick body are possibly immunogenic. Some researchers, using immunohistochemistry, have detected host antibodies in the gut, salivary glands and haemolymph of ticks engorged on resistant animals. The same technique has helped considerably in determining antigenic sites or antibody targets in other arthropods. Consequently, immunohistochemistry techniques were used in this study to detect cross-reactivity between sera raised against Amblyomma cajennense (Fabricius, 1787) with Amblyomma hebraeum (Koch, 1844), and vice versa. The results show the existence of shared antigens between the 2 tick species. In general, our results point more to a 1-way cross-reactivity of A. hebraeum with A. cajennense than a reciprocal cross-reactivity, suggesting that A. hebraeum is more immunogenic than A. cajennense.

Factors affecting the seroprevalence of Toxoplasma gondii infection in wild rabbits (Oryctolagus cuniculus) from Spain

Sera from 456 wild rabbits (Oryctolagus cuniculus) collected between 1992 and 2003 from five geographical regions of Spain were examined for antibodies to Toxoplasma gondii by the modified agglutination test. Antibodies to T. gondii were found in 65 (14.2%) wild rabbits. Prevalence of infection was significantly higher in samples collected from wild rabbits from Catalonia, northeast Spain (53.8%), where rabbits lived in forest, compared to other areas (Huelva and Cádiz, Andalucía, south Spain; Toledo, Castilla-La Mancha, central Spain; and Zaragoza, Aragón, northeast Spain) with more dry conditions, where prevalence ranged from 6.1 to 14.6%. No differences were observed on prevalence and age (young animals <7 months of age compared to older animals), sex, date of samples collection or season of samples collection. The results indicate that prevalence of T. gondii in some areas of Spain is high, and this finding could have environmental and/or public health implications if wild rabbits are to be used as a source of food.

Development of Nematodirus spathiger (Nematoda, Molineoidea) in the rabbit and comparison with other Nematodirus spp parasites of ruminants

The morphogenesis and chronology of the life cycle of Nematodirus spathiger (Railliet, 1896), a parasite of ruminants, were studied in detail in an experimental host. Twenty-four worm-free rabbits were each infected per os with N. spathiger larvae and were killed at 12 h after infection (12 HAI) and every day from 1 DAI to 23 DAI. By 12 HAI, all the larvae were exsheathed and present in the small intestine. The third moult occurred between 4 DAI and 5 DAI. The last moult occurred between 13 DAI and 16 DAI. The prepatent period lasted 21-24 days. The distribution of N. spathiger along the small intestine of the rabbit was assessed. The chronology of the life cycles was compared for various Nematodirus spp from ruminants in their natural hosts and in the rabbit (N. battus, N. spathiger).

Sub-clinical infection as an effective protocol for obtaining anti-Leishmania chagasi amastigote antibodies of different animal species

This work aims at identifying an effective protocol to raise anti-Leishmania chagasi amastigote antibodies in different animal species. Protocols of immunization by subcutaneous injections of L. chagasi promastigote and amastigote lysates or by either intravenous or subcutaneous inoculation of live metacyclic promastigotes were assessed in mice, rabbits, and dogs. The immunization with live promastigotes produced a strong humoral immune response against L. chagasi amastigotes in all three animal species. The sera from animals immunized with the promastigote lysate did not react with amastigotes and, conversely, the sera from mice immunized with the amastigote lysate did not react with promastigotes. Taken all data together, the immunization through infection with metacyclic promastigotes was considered the most satisfactory way to immunize animals for obtaining anti-amastigote and anti-promastigote antibodies, since it did not only allowed the obtention of antibody against the two forms of the parasite, but it is also cheap, less laborious than carrying out the purification of amastigotes from infected tissues and avoid the use of a large number of hamsters for obtention the amastigotes, necessary to produce the immunogenic lysates. Furthermore, this immunization protocol was comparable to the amastigote lysate immunization protocol for the obtaining of mouse monoclonal antibodies (mAbs).

Fasciola gigantica: immunization of rabbits with proteins isolated from coproantigen

Two fractions were isolated from coproantigen by ion-exchange chromatography in which DEAE cellulose was utilized. Both fractions and crude antigen were characterized by SDS-polyacrylamide gel electrophoresis which revealed 13 bands of molecular weight ranged from 205-31 in crude coproantigen. While fraction I resolved into six bands of molecular weight 198, 178, 148, 111, 101 & 45. Fraction II showed seven bands of 191 KDa, 178KDa, 166KDa, 118KDa, 98.5KDa, 72KDa & 32KDa. Fraction 1I was higher immunoreactivity than fraction by ELISA. Three immunoreactive bands of 191KDa, 118KDa & 98.5KDa were identified in fraction II using immunoblot assay. Five bands of 178KDa, 148KDa, 111KDa, 101KDa & 45KDa were detected in fraction I. Immunization of rabbits twice with fraction II in Freund's adjuvant with two weeks interval followed by challenge with F. gigantica metacercariae resulted in 66.6% protection from infection. The protection was assessed by detect-ion of hepatic damage, worm recoveries and antibody response. High level of IgG response in vaccinated rabbits than control infected ones occurred and being responsible for the recorded protection.

Determination of Trichuris skrjabini by sequencing of the ITS1-5.8S-ITS2 segment of the ribosomal DNA: comparative molecular study of different species of trichurids

Adults of Trichuris skrjahini have been isolated from the cecum of caprine hosts (Capra hircus), Trichuris ovis and Trichuris globulosa from Ovis aries (sheep) and C. hircus (goats), and Trichuris leporis from Lepus europaeus (rabbits) in Spain. Genomic DNA was isolated and the ITS1-5.8S-ITS2 segment from the ribosomal DNA (rDNA) was amplified and sequenced by polymerase chain reaction (PCR) techniques. The ITS1 of T. skrjabini, T. ovis, T. globulosa, and T. leporis was 495, 757, 757, and 536 nucleotides in length, respectively, and had G + C contents of 59.6, 58.7, 58.7, and 60.8%, respectively. Intraindividual variation was detected in the ITSI sequences of the 4 species. Furthermore, the 5.8S sequences of T. skrjabini, T. ovis, T. globulosa, and T. leporis were compared. A total of 157, 152, 153, and 157 nucleotides in length was observed in the 5.8S sequences of these 4 species, respectively. There were no sequence differences of ITS1 and 5.8S products between T. ovis and T. globulosa. Nevertheless, clear differences were detected between the ITS1 sequences of T. skrjabini, T. ovis, T. leporis, Trichuris muris, and T. arvicolae. The ITS2 fragment from the rDNA of T. skrjabini was sequenced. A comparative study of the ITS2 sequence of T. skrjabini with the previously published ITS2 sequence data of T. ovis, T. leporis, T. muris, and T. arvicolae suggested that the combined use of sequence data from both spacers would be useful in the molecular characterization of trichurid parasites.

A comparison of homologous genes encoding aminopeptidases among bird and human Encephalitozoon hellem isolates and a rabbit E. cuniculi isolate

Encephalitozoon cuniculi and E. hellem are often recognized as the agents of human microsporidiosis, but less than optimal therapy is available for treatment. The identification of enzymes critical to the parasitic life cycle is an important step in finding targets for potential drug development. Aminopeptidase gene sequences were obtained from cDNA and gDNA from avian and human E. hellem isolates and from a rabbit E. cuniculi isolate. At the amino acid level, the aminopeptidase sequences from the E. hellem human and bird isolates share >99% identity and are nearly 70% identical with the E. cuniculi sequence. Conserved HEXXH and GAMEN motifs classify the predicted aminopeptidase in the MA clan of the M1 family. The obtained aminopeptidase gene sequences are likely homologous to the previously reported E. cuniculi glutamyl aminopeptidase. The conservation of this aminopeptidase between species and divergence from mammalian aminopeptidases indicate that this enzyme may be a valid target for drug therapy.

Competition and mutualism among the gut helminths of a mammalian host

Most animal species are infected with multiple parasite species; however, the role of interspecific parasite interactions in influencing parasite dynamics and shaping parasite communities has been unclear. Although laboratory studies have found evidence of cross-immunity, immunosuppression and competition, analyses of hosts in the field have generally concluded that parasite communities are little more than random assemblages. Here we present evidence of consistent interspecific interactions in a natural mammalian system, revealed through the analysis of parasite intensity data collected from a free-ranging rabbit (Oryctolagus cuniculus) population, sampled monthly for a period of 23 yr. The wild rabbit plays host to a diverse gut helminth community that reflects the communities seen in other economically important domestic herbivores. These findings suggest that parasite interactions could have profound implications for the dynamics of parasite communities. The efficacy of parasite control programmes could be jeopardized if such interactions are not taken into account. In contrast, a clear understanding of such interactions may provide the basis for the development of more environmentally acceptable methods of parasite control.

Comparison of the infection rate of tsetse, Glossina morsitans morsitans, fed in vitro or in vivo

Studies were made of infection rates of trypanosomes in the tsetse fly Glossina morsitans morsitans Westwood (Diptera: Glossinidae) when maintained in vivo (rabbits) or in vitro on high quality, gamma-irradiated, sterile defibrinated bovine blood, obtained from the Entomology Unit of the International Atomic Energy Agency (IAEA). For both Trypanosoma congolense Broden and T. b. brucei Plimmer & Bradford, in vitro maintenance significantly reduced the proportion of flies that developed mature metacyclic trypanosome infections.