Natural Besnoitia sp. infection in domestic rabbits from Argentina

Besnoitia sp. are apicomplexan coccidian parasites affecting several species of mammals and cold-blooded animals in several countries. Besnoitia sp. tissue cysts were seen in several tissues of five rabbits from a rabbit breeder in La Plata, Argentina. Bradyzoites released from macroscopic tissue cysts were inoculated onto bovine monocytes, and into interferon gamma gene knockout (KO) mice. Besnoitia sp. tachyzoites were seen in the peritoneal exudate of KO mice on day 10 pi and these tachyzoites were infective to other KO mice. Tachyzoites grown in cell culture were infective to gerbils (Meriones unguiculatus). This is the first report of Besnoitia sp. infection in any host in Argentina.     

Clinical, pathological and epidemiological findings in three outbreaks of ovine protozoan myeloencephalitis

Ovine protozoan myeloencephalitis is a disease of sheep associated with the apicomplexan protozoan Sarcocystis tenella. This paper describes the clinical, pathological and epidemiological findings in three affected flocks from a well-defined geographical area. Clinical signs were restricted to sheep under one year old in their first winter and were first observed at least 42 days after they had been moved off the hill grazing areas to low ground pasture, or after they were given conserved forage. The findings are discussed in relation to the timescale of the life cycle of S. tenella and it is suggested that clinical disease was precipitated by the change from a low level of exposure to infection on the hill to a high level of exposure through contaminated pasture or forage. Possible preventive strategies are discussed.     

Neospora caninum: adoptive transfer of immune lymphocytes precipitates disease in BALB/c mice

Neospora caninum is a recently described apicomplexan parasite first isolated from a dog in 1988 and has subsequently been shown to infect a wide range of mammals. In mice, Neospora can cause primary pneumonia, myositis, encephalitis, radiculoneuritis, and pancreatitis. Whereas, certain aspects of the host immune response to Toxoplasma gondii have been well studied, not as much is known about the full immune response to Neospora. This paper examines whether or not immune splenocytes are able to adoptively transfer protection against N. caninum infection in BALB/c mice. Mice receiving immune enriched CD8+ cells had severe neurological signs by 19 days post infection. Mice receiving immune enriched CD4+ cells had mild neurological signs on day 22 post infection. It would appear that additional immune cells can precipitate disease in the presence of circulating lymphocytes.     

Sequence conservation in the rRNA first internal transcribed spacer region of Babesia gibsoni genotype Asia isolates

Babesia gibsoni genotype Asia is a small, tick-transmitted intraerythrocytic protozoan that parasitizes dogs. Reports suggest that it is increasingly diagnosed in the United States. The clinical outcome of infection with this piroplasm is often variable, leading us to hypothesize that the different clinical outcomes resulting from B. gibsoni genotype Asia infection are due to genetically distinguishable strains that differ in virulence. As a first step to assess the genetic variability of B. gibsoni isolates originating from the southeastern United States, we sequenced the rRNA first internal transcribed spacer region of recent isolates from Georgia and Alabama, and compared these sequences with isolates originating from Japan and Australia. All isolates examined proved to be genetically identical at the first internal transcribed spacer region, although this region differed distinctly from other Babesia species and closely related apicomplexan species. Although negating our hypothesis, this information gives us insight into the recent evolutionary history and spread of B. gibsoni genotype Asia in dogs in the U.S. Our research suggests that the gradual rise in prevalence of canine babesiosis due to B. gibsoni genotype Asia in the United States may be a result of clonal expansion of a single strain within a susceptible host population.     

First report of naturally acquired clinical sarcocystosis in a pig breeding stock

A two-year-old Large White boar from a pig breeding stock in an indoor farm in Switzerland presented anorexia, reduced general condition and fever. Despite antibiotic and anti-inflammatory treatment, the boar developed severe dyspnoea and cyanosis, and died after 4 days. At necropsy, no gross lesions were observed. Histopathologically, multifocal degeneration and necrosis of myocardial fibers with interstitial edema, severe multifocal non-suppurative myocarditis and hepatitis, and non-suppurative interstitial nephritis were observed. In heart samples, groups of organisms resembling apicomplexan tachyzoites were seen associated with the lesions. A PCR using the primers COC1-COC2 that target a conserved region of the small-subunit rRNA gene of Apicomplexa was performed with DNA from paraffin-embedded tissues. An amplification product of about 350 bp was obtained from heart samples. A sequence analysis showed 100% identities with GenBank sequences reported for Sarcocystis miescheriana. The histopathological observations and molecular findings in combination with the clinical signs, and absence of other pathologic agents highly suggested that an acute infection with S. miescheriana was the cause of death in this boar. To our knowledge, this the first report of fatal acute sarcocystosis after natural infection in a pig breeding herd.     

Molecular detection of Mycoplasma wenyonii and 'Candidatus Mycoplasma haemobos' in cattle in Hokkaido, Japan

Blood samples from 78 cattle were tested for hemoplasma infection using molecular methods. PCR and sequence analysis revealed that 17 cattle were infected with Mycoplasma wenyonii, while 13 were infected with 'Candidatus Mycoplasma haemobos'. Four animals were infected with both species. This is the first study to report hemoplasma species infection among cattle in Japan.     

The role of Neospora caninum and Toxoplasma gondii in spontaneous bovine abortion in Argentina

The aim of the present work was to evaluate the role of Neospora caninum and Toxoplasma gondii infections in spontaneous bovine abortions in Argentina. Based on histopathological results, 70 presumptive cases of apicomplexan protozoal abortion from a total of 666 cases of spontaneous bovine abortion submitted to the National Institute of Agrarian Technology, Balcarce, from 1999 to 2007 were included in this study. N. caninum infection was diagnosed by an indirect fluorescent antibody test (IFAT), by immunohistochemistry (IHC) and by nested-PCR. T. gondii infection also was diagnosed by nested-PCR. DNA from fetuses was extracted primarily from CNS tissues. Heart, liver, muscle and/or placenta were processed when nervous tissue was not available. Sixty-six (9.9%) fetuses were positive by at least one technique (IFAT, IHC or nested-PCR) for N. caninum infection. Overall, there was poor agreement among results obtained by these diagnostic techniques. In contrast, no Toxoplasma-infection was detected in any aborted bovine fetus.     

自噬通路及其在顶复门原虫入侵发育中的作用

自噬(autophagy)是细胞通过降解自身大分子物质或破损细胞器等来维持胞内稳态的一种平衡机制.近年来在顶复门原虫与宿主细胞相互作用研究中发现,顶复门原虫不但可诱导宿主细胞产生自噬并启动天然免疫途径清除寄生虫,亦可进化出独特的机制来抵抗宿主细胞自噬甚至利用其为自身生长提供条件.不同种类顶复门原虫与宿主细胞互作方式不同...     

Larval Gulf Coast ticks (Amblyomma maculatum) [Acari: Ixodidae] as host for Hepatozoon americanum [Apicomplexa: Adeleorina].

Laboratory-reared larval Gulf Coast ticks (GCTs) (Amblyomma maculatum) were exposed experimentally and found to acquire Hepatozoon americanum infection while feeding on parasitemic dogs. These ticks supported gamogonic and sporogonic development of the apicomplexan, and oocysts from newly molted nymphs were infectious for a dog. Other nymphs from this cohort that were allowed to feed on a blood-parasite naive sheep molted normally; the resulting adult ticks contained oocysts that were infectious for another dog. Merogonic development of H. americanum in the dogs and the resulting lesions/disease appeared similar, irrespective of whether infectious oocysts were derived from nymphal or adult ticks that acquired infection as larvae. In the system previously known, nymphal ticks acquire infection and adults harbor infective oocysts, which vertebrate hosts ingest. Given that larval A. maculatum can acquire infection and nymphs can harbor viable oocysts as demonstrated by this study, the potential variety of vertebrate hosts that can alternate with GCTs in maintaining an endemic cycle is considerably expanded.     

The efficacy of a mixture of trimethoprim and sulphaquinoxaline against Plasmodium gallinaceum malaria in the domesticated fowl Gallus gallus

The apicomplexan parasite Plasmodium gallinaceum has not been much studied from the veterinary standpoint. Although it causes malaria in domesticated chickens, no effective drugs appear to be commercially available. A mixture of trimethoprim and sulphaquinoxaline (TMP/SQX, ratio 1:3), with a wide spectrum of activity against bacteria and coccidia, is here shown to be also efficacious against blood-induced P. gallinaceum malaria when administered therapeutically in the feed of chickens for 5-day periods, beginning on the day before infection, or on the day of infection, or up to four days after infection. Chickens were protected against mortality and reduction of weight gain. Three other criteria of efficacy, which showed good correlation with each other and also with the two commercial performance criteria, were the production of green diarrhoea (due to biliverdin), parasitaemia and reduced haematocrit values. When TMP/SQX treatments were initiated sooner than five days after infection, parasites were almost entirely eliminated from the blood, whereas treatments initiated later than four days after infection failed to protect birds against clinical disease. Birds protected by TMP/SQX against primary infection with P. gallinaceum were immune to clinical malaria when exposed to a severe blood-induced challenge of P. gallinaceum 28 days later.     

Dermatitis in a dog associated with an unidentified Toxoplasma gondii-like parasite

Protozoal dermatitis was diagnosed in a 6-year-old female Great Dane dog from Rio de Janeiro, Brazil. The dog died because of a chronic illness with an Ehrlichia-like organism. Numerous apicomplexan parasites were identified histologically in the section of dermal lesions. The protozoan reacted with Toxoplasma gondii polyclonal rabbit serum but not with Neospora caninum or Sarcocystis neurona antibodies. Ultrastructurally, the protozoa was not T. gondii because it had schizont-like structures with merozoites arranged around a prominent residual body, and the merozoites had several rhoptries with electron-dense contents; rhoptries in T. gondii tachyzoites are electron-lucent and a residual body is not found in groups of tachyzoites. This is the first report of unidentified T. gondii-like protozoa in the skin of a dog.     

顶复门原虫电子转移链代谢及Ⅱ型NADH脱氢酶研究进展

顶复门原虫是包括刚地弓形虫、疟原虫及球虫等在内的一大类寄生性原虫的总称,可引起重要的人畜寄生虫病.抗顶复门原虫药物的长期使用,甚至是滥用,使得这类寄生虫对现有药物产生了明显的抗药性,急需开发新型药物.Ⅱ型NAD(P)H脱氢酶是电子转移链途径中的关键酶,由于其仅存在于某些植物、细菌、真菌和寄生原虫等一些低等生物体内,而在高等动物体内缺失,是研发新型抗感染性药物的重要靶标.笔者主要针对顶复门原虫线粒体电子转移链代谢途径以及Ⅱ型NAD(P)H脱氢酶的研究概况进行综述.     

Red blood cell volume as a predictor of fatal reactions in cattle infected with Theileria parva Katete

A comparison of mean corpuscular volume (MCV) and packed cell volume (PCV) was made between cattle undergoing lethal and non-lethal reactions following experimental infections with the apicomplexan protozoa, Theileria parva Katete. This work confirmed that anaemia occurs in infected animals. However, the fall in PCV was steeper in lethal reactions compared to non-lethal reactions. Our results show that animals with initially lower MCV values are more prone to fatal reaction, despite having normal PCV profiles. The study also found that small red blood cells are more likely to be infected with T. parva. These findings suggest that animals with a higher proportion of small red blood cells in circulation will be more likely to succumb to T. parva infections. The potential for using MCV as a predictor of the outcome of infection challenge is discussed.     

The first report of Hepatozoon sp. (Apicomplexa: Hepatozoidae) in neotropical felids from Brazil

In order to investigate the occurrence of Hepatozoon infection in Neotropical felids from Brazil, blood from the jugular or cephalic vein was taken from 29 non-domestic felids including ocelot (Leopardus pardalis), little spotted cat (Leopardus tigrinus), margay (Leopardus wiedii), and jaguarondi (Puma yagouaroundi) from the Northeast region of Brazil. Hepatozoon infection was confirmed by light microscopy and molecular techniques. The results showed five naturally infected felids. Partial sequences of the 18S rRNA gene of the Hepatozoon sp. from these felids were further analyzed. Sequences revealed that the isolates found are closely related to Hepatozoon sp. from domestic cats in Spain. Hepatozoon species from Neotropical felids were identified molecularly and characterized for the first time. This is also the first report of Hepatozoon infection in a little spotted cat.     

Oxalate-producing pulmonary aspergillosis in an alpaca

An aging lactating alpaca was presented in sternal recumbency. Although bright and alert, she did not respond to symptomatic treatment and was euthanized 5 weeks after initial presentation. Gross postmortem examination revealed purulent material in the pulmonary airways. Histologic examination of the lungs revealed an extensive pyogranulomatous pneumonia with bronchiectasis. There were abundant fungal hyphae and high numbers of associated oxalate crystals, which were presumed to have been produced by the fungus. Low numbers of yeast cells were also present. Microbiological culture of tissues on horse blood agar and Sabouraud's agar identified the fungus to be Aspergillus niger. There was also moderate growth of Candida albicans. Calcium oxalate crystals in cytologic and histologic preparations can suggest an underlying Aspergillus infection. This is the first reported veterinary case of pneumonia due to Aspergillus niger infection and the associated production of oxalate crystals.     

Determination of the activity of pyrimethamine, trimethoprim, sulfonamides, and combinations of pyrimethamine and sulfonamides against Sarcocystis neurona in cell cultures.

Equine protozoal myeloencephalitis (EPM) is a neurologic syndrome in horses from the Americas and is usually caused by infection with the apicomplexan parasite, Sarcocystis neurona. The activities of pyrimethamine, trimethoprim, sulfachloropyridazine, sulfadiazine, sulfadimethoxine, sulfamethoxazole, sulfamethazine, and sulfathiazole were examined against developing S. neurona merozoites in bovine turbinate cell cultures. A microtiter plate host cell lesion based assay was used to determine the effects of agents on developing merozoites. A cell culture flask assay was used to determine if selective concentrations of the agents killed or only inhibited development of S. neurona. Pyrimethamine was coccidiocidal at 1.0 microg/ml and trimethoprim was coccidiocidal at 5.0 microg/ml. None of the sulfonamides had activity when used alone at 50.0 or 100.0 microg/ml. Combinations of sulfonamides (5.0 or 10.0 microg/ml) with 0.1 microg/ml pyrimethamine demonstrated improved activity.     

Plasmodium (Bennettinia) juxtanucleare infection in a captive white eared-pheasant (Crossoptilon crossoptilon) at a Japanese zoo

An adult male white eared-pheasant (Crossoptilon crossoptilon) at a Japanese zoo exhibited lethargy and emaciation. Microscopic examination of a blood smear revealed a haemosporidian parasitic infection. Based on the morphological characteristics and molecular analysis of the parasite, it was identified as Plasmodium (Bennettinia) juxtanucleare. This is the first report of P. juxtanucleare infection in bird species belonging to the genus Crossoptilon. Caution against avian malaria infection is required for the conservation of endangered bird species in zoos.     

Chronic active hepatitis in dogs associated with leptospires.

Chronic active hepatitis was diagnosed in five American Foxhounds from one kennel. Spirochetes were demonstrated in the liver in four of the dogs. A rising titer to Leptospira interrogans serovar grippotyphosa was found in the fifth dog, although spirochetes were not demonstrated in tissues. A serologic survey at the kennel revealed evidence of exposure of 6 of 13 dogs to grippotyphosa. This is the first report of an association between chronic active hepatitis leptospiral infection in any species.     

Immunological aspects of Marek's disease in chickens with maternal antibodies]

The dynamics of the production of immunoprecipitation antibodies to Marek's disease virus was studied in the serum of chickens with maternal antibodies in relation to the occurrence of the immunoprecipitation antigens of Marek's disease virus in feather follicles. One-day-old chickens were infected by the contact method with Marek's disease virus. The first occurrence of immunoprecipitation antigen was detected on the 14th day after infection and this occurrence persisted throughout the experiment, i. e. until the 112th day after infection. The antibodies were first detected the 28th day after infection and their titre kept rising until the 98th day after infection. Immunoprecipitation antibodies and antigens of Marek's disease virus were detected in some tumorously changed kidneys. Immunoelectrophoretic examination revealed in the same kidneys immunoglobulins of the class IgY, IgA and beta-globulin. The slowest-migrating fraction of IgY, together with IgA, beta-globulin and C-reactive protein were detected in the skin extracts from infected poultry. Indirect haemagglutination enabled the detection of the presence of haemagglutination antibodies in rabbit immunoglobulin to the skin antigen of Marek's disease virus, and in avian immunoglobulin to the same virus. Haemagglutination antigen was revealed in the extract from tumorously changed kidneys.