Ultrastructure and pathology of Besnoitia caprae in the naturally infected goats of Kerman, East of Iran

An update on epidemiology and clinical aspects of besnoitiosis in livestock and wildlife in sub-Saharan Africa: A systematic review

Besnoitiosis is a parasitic disease of economic importance caused by cyst-forming protozoa from the genus Besnoitia. The disease affects the skin, subcutis, blood vessels, and mucous membranes of the animals. It is traditionally endemic in the tropical and sub-tropical regions of the world, and causes enormous economic loss associated with impaired productivity and reproduction, as well as skin lesions. Therefore, knowledge of the epidemiology of the disease, including the current Besnoitia species occurring in sub-Saharan Africa, the wide range of mammalian species hosts they use as intermediate hosts, and the clinical signs manifested by infected animals is crucial in developing effective prevention and control measures. This review collected information from peer-reviewed publications involving the epidemiology and clinical signs of besnoitiosis in sub-Saharan Africa using four electronic databases. Results showed that B. besnoiti, B. bennetti, B. caprae, B. darlingi-like and unidentified Besnoitia spp. were found naturally infecting livestock and wildlife across nine reviewed sub-Saharan African countries. Besnoitia besnoiti was the most common species, occurring in all nine reviewed countries, and utilised a wide range of mammalian species as intermediate hosts. Prevalence of B. besnoiti ranged from 2.0 to 80.3%, and B. caprae 5.45-46.53%. Infection rate was high with serology compared to other techniques. Some of the typical signs of besnoitiosis included sand-like cysts on the sclera conjunctiva, nodules in the skin, thickening and wrinkling of the skin and alopecia. Inflammation, thickening and wrinkling of the scrotum were observed in bulls, and lesions on the scrotum deteriorated progressively and became generalized in some cases in spite of treatment. There is still a need for surveys focusing on detecting and identifying Besnoitia spp. using molecular techniques in combination with serological, histology and visual observation, and scoping their natural intermediate and definitive hosts, as well as assessing the burden of the disease animals reared on different husbandry systems in sub-Saharan Africa.

Optimization of murine model for Besnoitia caprae

It has been shown that mice, particularly the BALB/c ones, are susceptible to infection by some of the apicomplexan parasites. To compare the susceptibility of the inbred BALB/c, outbred BALB/c and C57 BL/6 to Besnoitia caprae inoculation and to determine LD50, 30 male inbred BALB/c, 30 outbred BALB/c and 30 C57 BL/6 mice were assigned into 18 groups of 5 mice. Each group was inoculated intraperitoneally with 12.5 × 10(3), 25 × 10(3), 5 × 10(4), 1 × 10(5), 2 × 10(5) tachyzoites and a control inoculum of DMEM, respectively. The inbred BALB/c was found the most susceptible strain among the experienced mice strains so the LD50 per inbred BALB/c mouse was calculated as 12.5 × 10(3.6) tachyzoites while the LD50 for the outbred BALB/c and C57 BL/6 was 25 × 10(3.4) and 5 × 10(4) tachyzoites per mouse, respectively. To investigate the impact of different routes of inoculation in the most susceptible mice strain, another seventy five male inbred BALB/c mice were inoculated with 2 × 10(5) tachyzoites of B. caprae via various inoculation routes including: subcutaneous, intramuscular, intraperitoneal, infraorbital and oral. All the mice in the oral and infraorbital groups survived for 60 days, whereas the IM group showed quicker death and more severe pathologic lesions, which was then followed by SC and IP groups. Therefore, BALB/c mouse is a proper laboratory model and IM inoculation is an ideal method in besnoitiosis induction and a candidate in treatment, prevention and testing the efficacy of vaccines for besnoitiosis.

Suspension culture of Besnoitia caprae by murine macrophage

Besnoitia caprae is a tissue cyst-forming protozoan that infects goats and has considerable economic importance in certain regions of Asia and Africa. Murine macrophage J774 cell line was inoculated with tachyzoites of Besnoitia caprae (BC-Pars isolate) collected from mice. A significant growth of tachyzoites was observed in J774. Mice were inoculated with tachyzoites harvested from J774 cell culture. Skin samples from the mice infected with tachyzoites of BC-Pars were PCR positive. One mouse showed alopecia and skin lesions on 45 DPI. Dermal lesions started from around right eye and gradually developed more and more. After euthanasia on 60 DPI, histopathological evaluation of skins around the eye showed necrosis of the epidermis and follicular adnexa with chronic inflammatory cell infiltration. Histopathological sections of their skin showed the presence of necrosis and mononuclear cell infiltration. To the authors' knowledge, this is the first report of successful production of Besnoitia caprae tachyzoites was achieved in vitro by suspension culture technique. Another interesting finding is the report of the alopecia and skin lesions around the eye in mouse that quite similar to lesions of goats due to infection of Besnoitia caprae.

Proteomics reveals differences in protein abundance and highly similar antigenic profiles between Besnoitia besnoiti and Besnoitia tarandi

Besnoitia besnoiti and Besnoitia tarandi are two cyst-forming apicomplexan parasites of the genus Besnoitia. B. besnoiti uses cattle as an intermediate host, in which it causes a disease that progresses in two sequential phases: the acute anasarca stage and the chronic scleroderma stage. Reindeer and caribou act as intermediate hosts for B. tarandi, which causes clinical signs similar to those caused by B. besnoiti. Previous studies demonstrated high molecular similarity, as determined by 18S and ITS-1 RNA sequences, between these Besnoitia spp., and strong serological cross-reactivity between these species has recently been demonstrated. Thus, a difference gel electrophoresis approach and mass spectrometry analysis were used to describe the proteomes and explore differences in protein abundance between B. besnoiti and B. tarandi in tachyzoite extracts. Immunoproteomes were also compared using 2-DE immunoblotting with polyclonal sera from experimentally infected rabbits. From approximately 1400 spots detected in DIGE-gels, 28 and 29 spots were differentially abundant in B. besnoiti and B. tarandi tachyzoites, respectively (± 1.5-fold, p<0.05). Four and 13 spots were exclusively detected in B. besnoiti and B. tarandi, respectively. Of the 32 differentially abundant spots analyzed by MALDI-TOF/MS, 6 up-regulated B. besnoiti proteins (LDH; HSP90; purine nucleoside phosphorylase and 3 hypothetical proteins) and 6 up-regulated B. tarandi proteins (G3PDH; LDH; PDI; mRNA decapping protein and 2 hypothetical proteins) were identified. Interestingly, no specific antigen spots were recognized by sera on any of the Besnoitia species studied and a similar antigen profile has been observed for B. tarandi and B. besnoiti sera when cross reactions were studied. This fact corroborates the difficulty in discerning Besnoitia infections using current serological assays. The present study underscores the importance of sequencing the B. besnoiti genome for species diversity studies of the genus Besnoitia.

Naturally acquired bovine besnoitiosis: histological and immunohistochemical findings in acute, subacute, and chronic disease

The pathogenesis of bovine besnoitiosis, a disease of increasing concern within Europe, is still incompletely understood. In this study, disease progression after natural infection with the causative apicomplexan Besnoitia besnoiti was monitored in histological skin sections of 5 individual female cattle over time. High-frequency skin sampling of 2 cattle with mild and 2 with severe acute, subacute, and chronic besnoitiosis, as well as from 1 animal during subclinical disease, enabled documentation from the beginning of the disease. Skin sections were stained with hematoxylin and eosin and Giemsa, periodic acid-Schiff reaction, and anti-Besnoitia immunohistochemistry. In all 4 clinically affected animals, tachyzoite-like endozoites could be detected for the first time by immunohistochemistry, and tissue cyst evolution was monitored. Besnoitiosis-associated lesions were not detected in the animal showing the subclinical course. Because of the inconsistency of the nomenclature of Besnoitia tissue cyst layers in the literature, a new nomenclature for B. besnoiti cyst wall layers is proposed: tissue cysts consist of a hypertrophied host cell with enlarged nuclei, an intracytoplasmic parasitophorous vacuole with bradyzoites, a sometimes vacuolated inner cyst wall, and an outer cyst wall in more developed cysts. Inner and outer cyst walls can be readily distinguished by using special stains. In 1 animal, extracystic B. besnoiti zoites were immunohistochemically detected during the chronic stage. At necropsy, the 2 severely affected cows displayed large numbers of B. besnoiti cysts in a variety of tissues, including the corium of the claws, contributing mainly to the development of chronic laminitis in these 2 cases.

Caprine besnoitiosis: an emerging threat and its relationship to some other infections of ungulates by Besnoitia species

Caprine besnoitiosis, caused by the cyst-forming protozoal apicomplexan Besnoitia caprae appears to be endemic in Kenya, Nigeria and Iran, but has yet to be detected in other parts of the world. The infection causes an important parasitic disease of goats in affected developing countries. Bovine besnoitiosis, is a widespread disease of cattle in Africa, Asia (but not Iran) and southern Europe. Recent epidemiological data confirm that the incidence and geographical range of bovine besnoitiosis in Europe is increasing, which is why growing attention has been given to the condition during the past decade. This paper reviews pertinent information on the biology, epidemiology, pathology, clinical signs, diagnosis and control of caprine besnoitiosis, together with its similarities to, and differences from, bovine besnoitiosis. The serious economic consequences of besnoitiosis on goat breeding and local meat and hide industries is also considered.

Dynamics of Besnoitia besnoiti infection in cattle

Bovine besnoitiosis is caused by the cyst-forming apicomplexan parasite Besnoitia besnoiti. This disease progresses in two sequential phases: a febrile acute phase with oedemas and respiratory disorders, and a chronic phase characterized by the presence of subcutaneous tissue cysts and skin lesions. Serious consequences of the infection are poor body condition, sterility in bulls and eventual death. The role of host/parasite-dependent factors, which play a major role in the pathogenesis of the disease, is not yet fully elucidated. Isolate/strain virulence, parasite stage, dose and the route of parasite inoculation were studied under different experimental conditions, which make it difficult to compare the results. Data on host-dependent factors obtained from naturally infected cattle showed that (i) the seroprevalence of infection is similar in both sexes; (ii) seropositivity increases with age; (iii) both beef and dairy cattle are susceptible to the infection; and (iv) the cell-mediated immune response is likely to play a major role because a T cell response has been observed around several tissue cysts. Whether colostral antibodies are protective and to what extent the humoral immune response might reflect the disease/protection status require further research. Thus, a well-established experimental bovine model could help to clarify these important questions. The dynamics of B. besnoiti infection in cattle and available knowledge on relevant factors in the pathogenesis of the infection are reviewed in the present work.

First serosurvey of Besnoitia spp. infection in wild European ruminants in Spain

Besnoitia besnoiti has been reported to affect cattle, wildebeest, kudu and impala, and B. tarandi other wild ruminants (caribou, reindeer, mule deer and musk ox), causing similar characteristic clinical signs and lesions. However, both Besnoitia species have been reported in different geographical areas and the link between the sylvatic and domestic life cycles of Besnoita spp. in wild ruminants and cattle remains unknown. The aim of this study was to evaluate the presence of specific antibodies against Besnoitia spp. in wild ruminants in Spain. A wide panel of sera from red deer (Cervus elaphus) (n=734), roe deer (Capreolus capreolus) (n=124), chamois (Rupicapra pyrenaica) (n=170) and mouflon (Ovis musimon) (n=20) collected from different locations of Spain was analyzed. Beef cattle were present in all sampled areas and, interestingly, bovine besnoitiosis has been widely reported in some of them (e.g., Pyrenees and Central Spain). Sera samples were first examined with an Enzyme-Linked Immunosorbent Assay (ELISA). For red deer and roe deer, the ELISA was standardized with positive and negative control sera from several Cervidae species (100% Se and 98% Sp). Chamois and mouflon sera samples were tested with a previously reported ELISA validated for bovine sera (97% Se and 95% Sp) using protein G as a conjugate. Positive results by ELISA were confirmed a posteriori with a tachyzoite-based Western blot. Sixty-one sera samples from red deer and 17 sera samples from roe-deer were seropositive or doubtful by ELISA. All samples from mouflon were seronegative and 15 sera samples from chamois were considered doubtful. B. besnoiti exposure was only confirmed clearly by Western blot in one red deer and one roe deer from the Spanish Pyrenees where the disease is traditionally endemic. This is the first serological report of Besnoitia spp. infection carried out in European wild ruminants and the results show that specific antibodies are present at least in red deer and roe-deer. Thus, wild ruminants from endemic regions of bovine besnoitiosis should be further studied because they may be putative reservoirs of the parasite.

Serological evidence of Besnoitia spp. infection in Canadian wild ruminants and strong cross-reaction between Besnoitia besnoiti and Besnoitia tarandi

Bovine besnoitiosis, caused by Besnoitia besnoiti, is considered to be emergent in Europe and responsible for severe economic losses due to the chronic and debilitating course of the disease but has not been reported in North America. Besnoitia tarandi is a related species and it has been reported in reindeer and caribou from different locations of the Arctic Pole, including North America. Diagnosis of clinical besnoitiosis is largely based on the recognition of dermal grossly visible tissue cysts of Besnoitia. Nothing is known of cross reactivity between B. besnoiti and B. tarandi species. Here, we evaluated the use of serological tests employed in the diagnosis of bovine besnoitiosis for the detection of Besnoitia spp. infections in different wild ruminant species (caribou, elk, mule-deer, white-tailed deer, moose, muskox and bison) from Canada and investigated cross-reactivity between B. besnoiti and B. tarandi species by indirect immunofluorescence antibody test and Western blot. For this, species-specific antibodies were obtained in rabbits experimentally infected with B. besnoiti and B. tarandi. Marked cross reactivity was found between B. besnoiti and B. tarandi. For the first time, antibodies to Besnoitia spp. infection were found in 16 of 20 caribou (Ranginfer tarandus), seven of 18 muskox (Ovibos moschatus), one of three bison (Bison bison), but not in 20 elk (Cervus canadensis), 20 white tailed deer (Odocoileus virginianus), and 20 moose (Alces alces) in Canada; results were similar using B. besnoiti and B. tarandi as antigen. There was no cross reactivity between the two Besnoitia species, Neospora caninum and Toxoplasma gondii with the cut-offs applied that prevented to observe it. The present study provides evidence that the serological assays can be useful to accomplish large scale prevalence studies in caribou and other wildlife species. Further studies are needed to study sylvatic and domestic cycle of B tarandi and B. besnoiti.

Molecular pathology, taxonomy and epidemiology of Besnoitia species (Protozoa: Sarcocystidae)

Until recently, besnoitiosis has been a neglected disease of domestic animals. Now, a geographic expansion of the causing protozoan parasite Besnoitia besnoiti in livestock has been recognized and the disease in cattle is considered emerging in Europe. Bovine besnoitiosis leads to significant economic losses by a decline in milk production, sterility, transient or permanent infertility of bulls, skin lesions and increase of mortality in affected cattle population. Phylogenetically, the Besnoitia genus is closest related to the well studied and medically important protozoans, Toxoplasma gondii and Neospora caninum. In contrast, discriminative molecular markers to type and subtype large mammalian Besnoitia species (B. besnoiti, B. caprae, B. tarandi, B. bennetti) on a relevant level of species and strains are lacking. Similarly, these cyst-forming parasites may use two hosts to fulfill their life cycle, but this has not been proven for all large mammalian Besnoitia species yet. Most important though, the final hosts and transmission routes of these Besnoitia species remain mysterious. Here, we review aspects of parasite's pathology, speciation, phylogeny, epidemiology and transmission with a special focus on recent molecular studies of all to date known Besnoitia species. Using an integrated approach, we have tried to highlight some promising directions for future research.

Hematological and serum biochemical analyses in experimental caprine besnoitiosis

This study was undertaken to investigate the hematological and biochemical changes in experimentally infected goats with Besnoitia caprae from the time of infection till 360 days post-infection (PI). Six male goats were inoculated subcutaneously with 13 × 10(7) bradyzoites of B. caprae, and blood samples were collected from the jugular vein. The total erythrocyte and total leukocyte counts, hematocrit value, and differential leukocyte counts were determined. Serum biochemical analysis, including the total protein, albumin, total globulin, cholesterol, triglyceride, chloride, testosterone, calcium (Ca(2+)), inorganic phosphorus, sodium (Na(+)), potassium (K(+)), iron (Fe(2+)), glucose, serum amyloid A (SAA), haptoglobin (Hp), fibrinogen, ceruloplasmin, aspartate aminotransferase, alanine aminotransferase, creatine kinase, lactate dehydrogenase, and alkaline phosphatase, was undertaken. Skin biopsy from the limbs were collected at weekly intervals and histologically examined for Besnoitia cysts. Cysts were present in the skin biopsies of the leg of the infected goats from day 28 PI. There were variations in hematological analyses, but no significant difference was seen. From day 30 to 360 PI, results showed that SAA, Hp, fibrinogen, and ceruloplasmin concentrations increased, whereas testosterone concentrations decreased. Infected goats exhibited decrease of albumin and increase of serum total protein and globulin concentrations. By contrast, there were no significant differences in the remained analyses concentrations.

Histopathologic and Ultrastructural Studies on Experimental Caprine Besnoitiosis

The distribution pattern and associated tissue reactions with progressive changes in Besnoitia caprae cysts were investigated in 6 experimentally infected 16- to 20-month-old male goats. Each goat was subcutaneously inoculated with approximately 13 × 108 B caprae bradyzoites. The animals were examined daily for development of clinical besnoitiosis, and skin biopsies from distal parts of the limbs were taken at weekly intervals. At 15, 30, 60, 120, 180, and 365 days postinfection (DPI), 1 goat was euthanized. Samples were collected at autopsy from various organs for histologic and ultrastructural studies. No cysts were seen in tissue sections on 15, 30, and 365 DPI, but large numbers were present at 60, 120, and 180 DPI in the skin of the distal limbs, scrotum, and ears, with fewer in the tongue, palate, sclera, testicles, and spermatic cord. No cysts were seen in the lungs, liver, kidneys, spleen, central nervous system, or lymph nodes. Cyst numbers peaked at 60 DPI, then declined from 120 to 180 DPI. Degenerated cysts were relatively rare at 60 DPI but more numerous at 180 compared with 120. A granulomatous reaction—predominantly characterized by macrophages, lymphocytes, and plasma cells—surrounded each degenerated cyst. All goats showed testicular tubular degeneration with little or no spermatogenic activity. The sizes of cysts and their wall thickness, with the size of bradyzoites and some of their organelles, exhibited progressive chronologic changes.