Development of a protocol testing the ability of Stomoxys calcitrans (Linnaeus, 1758) (Diptera: Muscidae) to transmit Besnoitia besnoiti (Henry, 1913) (Apicomplexa: Sarcocystidae)

Seroprevalence and Factors Associated with Toxoplasma gondii, Neospora caninum, and Besnoitia besnoiti Infections in Cattle and Goats in Selangor, Malaysia

Apicomplexan parasites such as Toxoplasma gondii, Neospora caninum, and Besnoitia besnoiti are widely recognized as causes of production diseases in ruminants. This study aimed to investigate the serological occurrence of T. gondii, N. caninum, and B. besnoiti in cattle and goats from smallholder farms in Selangor, Malaysia. A cross-sectional study was conducted on 19 farms by collecting 404 bovine (n = 225) and caprine (n = 179) serum samples, which were then essayed for T. gondii, N. caninum, and B. besnoiti antibodies using commercially available ELISA test kits. Farm data and animal characteristics were documented, and the data were analyzed using descriptive statistics and logistic regression models. The seroprevalence of T. gondii at animal and farm levels in cattle was 5.3% (95% CI 1.2-7.4%) and 36.8% (95% CI 22.4-58.0%), respectively. Animal-level seropositivity for N. caninum was 2.7% (95% CI 0.4-4.2%) and 5.7% for B. besnoiti (95% CI 1.3-9.4%) with corresponding farm-level seropositivity of 21.0% and 31.5%, respectively. For the goat samples, a high animal- (69.8%; 95% CI 34.1-82.0%) and farm-level (92.3%) seropositivity was recorded for T. gondii, but was relatively lower for N. caninum antibodies, at 3.9% (95% CI 1.5-6.2%) and 38.4% (5/13). The factors associated with T. gondii seropositivity were older animals (above 12 months) (OR = 5.3; 95% CI 1.7-16.6), semi-intensive farms (OR = 2.2; 95% CI 1.3-6.2), the presence of either dogs or cats (OR = 3.6; 95% CI 1.1-12.3), a large herd size (>100 animals) (OR = 3.7; 95% CI 1.4-10.0), and a single source of replacement animals (OR = 3.9; 95% CI 1.6-9.6). These findings are vital in developing effective control measures against these parasites in ruminant farms in Selangor, Malaysia. More national epidemiological research is required to elucidate the spatial distribution of these infections and their potential impact on Malaysia's livestock industry.

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.

Validation of a commercial version of a competitive enzyme linked immunosorbent assay for the detection of antibodies to Besnoitia besnoiti

BACKGROUND

Several reports suggest a further spread of besnoitiosis to countries in which Besnoitia besnoiti-infected bovine herds have not been noticed yet. Cattle infected without clinical signs may represent reservoirs. Serological analyses in affected herds or animals from endemic regions are necessary to identify subclinical or inapparent infections and stop transmission to naïve animals or herds. The Monoscreen AbELISA Besnoitia besnoiti (BIO K 466) is based on a previously published in-house competitive ELISA, the Bb-cELISA1, but has a different test architecture. The present study aimed to use sera from a previous evaluation of Bb-cELISA1 to assess whether BIO K466 shows identical results. In addition, further well-characterized positive and negative samples were analysed to estimate diagnostic sensitivity and specificity.

METHODS

A first set of sera consisted of a total of 305 bovine sera, collected from German herds infected by B. besnoiti, Neospora caninum or Sarcocystis spp. Sera had been characterized by reference serological tests (i.e. immunoblot, immunofluorescence antibody test and an in-house indirect ELISA). A second set consisted of 200 confirmed B. besnoiti-positive sera from French herds. Negative cattle sera (n = 624) originated from Norway and The Netherlands, countries in which bovine besnoitiosis has not been reported yet.

RESULTS

Using the first set of sera, the BIO K466 showed an estimated diagnostic sensitivity of 97.9% (95% CI: 91.9%-99.6) and a diagnostic specificity of 99.5% (95% CI: 96.9%-100%) relative to reference serological tests. A direct comparison of the results revealed an almost perfect agreement between the results of the in-house Bb-cELISA1 and the commercialized version (kappa 0.98; 95% CI: 0.95-1). The validation using positive bovine sera from France and negative sera from other European countries revealed a diagnostic sensitivity of 97.5% (95% CI: 93.9%-99.1%) and specificity of 99.5% (95% CI: 98.5%-99.9%).

CONCLUSION

In conclusion, BIO K 466 appears to be a suitable tool to diagnose bovine besnoitiosis, but needs further validation especially in cases of inconclusive, suspected false-positive or -negative results in other serological tests.

First Expert Elicitation of Knowledge on Drivers of Emergence of Bovine Besnoitiosis in Europe

Bovine besnoitiosis (BB) is a chronic and debilitating parasitic disease in cattle caused by the protozoan parasite Besnoitia besnoiti. South European countries are affected and have reported clinical cases of BB. However, BB is considered as emerging in other countries/regions of central, eastern and northern Europe. Yet, data on drivers of emergence of BB in Europe are scarce. In this study, fifty possible drivers of emergence of BB in cattle were identified. A scoring system was developed per driver. Then, the scoring was elicited from eleven recognized European experts to: (i) allocate a score to each driver, (ii) weight the score of drivers within each domain and (iii) weight the different domains among themselves. An overall weighted score was calculated per driver, and drivers were ranked in decreasing order of importance. Regression tree analysis was used to group drivers with comparable likelihoods to play a role in the emergence of BB in cattle in Europe. Finally, robustness testing of expert elicitation was performed for the seven drivers having the highest probability to play a key role in the emergence of BB: i.e., (i) legal/illegal movements of live animals from neighbouring/European Union member states or (ii) from third countries, (iii) risk of showing no clinical sign and silent spread during infection and post infection, (iv) as a consequence, difficulty to detect the emergence, (v) existence of vectors and their potential spread, (vi) European geographical proximity of the pathogen/disease to the country, and (vii) animal density of farms. Provided the limited scientific knowledge on the topic, expert elicitation of knowledge, multi-criteria decision analysis, cluster and sensitivity analyses are very important to prioritize future studies, e.g., the need for quantitative import risk assessment and estimation of the burden of BB to evidence and influence policymaking towards changing (or not) its status as a reportable disease, with prevention and control activities targeting, firstly, the top seven drivers. The present methodology could be applied to other emerging animal diseases.

Emergence of Besnoitia besnoiti in Belgium

Bovine besnoitiosis is a cattle disease caused by a protozoan parasite called Besnoitia besnoiti. It is of serious economic concern to the cattle industry and also compromises animal welfare. For several years, it has been considered an emerging disease in some countries and regions located in the north of Europe far away from the known endemic areas in the south. This study describes the situation in the southern part of Belgium, where the parasite was recently introduced through imports of animals coming from departments of France where the disease was present. It details the detection of clinical cases as well as disease transmission features related to contacts during grazing and sales of infected cattle. A tracking and monitoring system was quickly set up and detected twelve outbreaks. Several cattle were controlled, but the lack of appropriate regulations weakens disease-management efforts. Hopefully, this predictable and silent introduction triggers the awareness of decision-makers about the need for an appropriate prevention and control policy, law enforcement, and the implementation of necessary measures to avoid bovine besnoitiosis becoming endemic in Belgium or other non-endemic countries. In addition, more proactive surveillance is required from authorities through threat analysis in the context of the risk of emergence or re-emergence of infectious animal diseases.

Insecticidal efficacy of afoxolaner against Stomoxys calcitrans (Diptera: Muscidae) in dogs

The insecticidal activity of oral afoxolaner (NexGard®) against stable flies Stomoxys calcitrans (Diptera: Muscidae) that had fed on dogs was evaluated in a blinded, randomised, and negative controlled efficacy study. The efficacy assessments were based on survival rates of fed flies after challenges to treated dogs. For a challenge, each dog was exposed to 50 unfed S. calcitrans for 30 minutes, after which time live fed flies were collected and incubated in an insectarium for viability assessment after 48, 72 and 96 hours. Fourteen dogs were randomly allocated to an untreated control group and an afoxolaner-treated group of seven dogs each. NexGard® was administered on Day 0 per label instructions to the treated group. All dogs were challenged on Days 1, 7, 14, 21 and 28. Efficacy was calculated by comparison of the proportion of incubated live fed flies for each individual after their related 30-min challenges in the control and treated groups after 48, 72 and 96 hours of incubation. A significant afoxolaner activity against S. calcitrans was demonstrated, with efficacy at 96 hours after blood-feeding ranging from 76.4 to 98.5% through Day 28.

Experimental Assessment of Zika Virus Mechanical Transmission by Aedes Aegypti

The pandemic emergence of several mosquito-borne viruses highlights the need to understand the different ways in which they can be transmitted by vectors to human hosts. In this study, we evaluated the propensity of Aedes aegypti to transmit mechanically Zika virus (ZIKV) using an experimental design. Mosquitoes were allowed to feed on ZIKV-infected blood and were then rapidly transferred to feed on ZIKV-free blood until they finished their meal. The uninfected blood meals, the mosquito abdomens, as well as the mouthparts dissected from fully and partially engorged mosquitoes were analyzed using RT-qPCR and/or virus titration. All the fully engorged mosquito abdomens were ZIKV-infected, whereas their mouthparts were all ZIKV-negative. Nonetheless, one of the partially engorged mosquitoes carried infectious particles on mouthparts. No infectious virus was found in the receiver blood meals, while viral RNA was detected in 9% of the samples (2/22). Thus, mechanical transmission of ZIKV may sporadically occur via Ae. aegypti bite. However, as the number of virions detected on mouthparts (2 particles) is not sufficient to induce infection in a naïve host, our results indicate that mechanical transmission does not impact ZIKV epidemiology.

Stomoxys calcitrans, mechanical vector of virulent Besnoitia besnoiti from chronically infected cattle to susceptible rabbit

Cattle besnoitiosis caused by Besnoitia besnoiti (Eucoccidiorida: Sarcocystidae) is a re-emerging disease in Europe. Its mechanical transmission by biting flies has not been investigated since the 1960s. The aim of this study was to re-examine the ability of Stomoxys calcitrans (Diptera: Muscidae) to transmit virulent B. besnoiti bradyzoites from chronically infected cows to susceptible rabbits. Three batches of 300 stable flies were allowed to take an interrupted bloodmeal on chronically infected cows, followed by an immediate bloodmeal on three rabbits (Group B). A control group of rabbits and a group exposed to the bites of non-infected S. calcitrans were included in the study. Blood quantitative polymerase chain reaction (qPCR) analyses, and clinical, serological and haematological surveys were performed in the three groups over 152 days until the rabbits were killed. Quantitative PCR analyses and histological examinations were performed in 24 tissue samples per rabbit. Only one rabbit in Group B exhibited clinical signs of the acute phase of besnoitiosis (hyperthermia, weight loss, regenerative anaemia and transient positive qPCR in blood) and was seroconverted. Parasite DNA was detected in four tissue samples from this rabbit, but no cysts were observed on histological examination. These findings indicate that S. calcitrans may act as a mechanical vector of B. besnoiti more efficiently than was previously considered.

Phenotypic susceptibility to pyrethroids and organophosphate of wild Stomoxys calcitrans (Diptera: Muscidae) populations in southwestern France

Stomoxys calcitrans (Diptera: Muscidae), is an important vector of lumpy skin disease and bovine besnoitiosis in Europe. Control of this biting fly could represent a keystone in the containment of this emerging disease. Reports of insecticide resistance in S. calcitrans are scarce in Europe. Therefore, the purpose of this study was to evaluate the phenotypic susceptibility to deltamethrin, cypermethrin and phoxim of five wild S. calcitrans populations from southwestern France, where transmission of bovine besnoitiosis is very prevalent. Adult S. calcitrans were caught at each study site and exposed to insecticide-impregnated filter papers under laboratory conditions. Quantities of active ingredients on filter papers corresponded to the recommended doses proposed by the manufacturers (37.5 mg a.i./m² of cattle's skin, 125 mg a.i./m² and 750 mg a.i./m² for deltamethrin, cypermethrin and phoxim respectively) were tested. Knock-down effects (KD) (1 h after the onset of exposure) and mortality rates (24 h and 48 h after exposure) were evaluated. Phoxim showed a rapid and full efficacy in all populations. However, the KD effects (37.5 to 97.5%) and the mortality rates at 48 h (10 to 91.25%) induced by the exposure to pyrethroids varied greatly according to the study site but none of the populations showed full susceptibility. Therefore, the current recommended doses of these pyrethroids are probably less efficient than expected in the field and should be considered with caution in the control of bovine besnoitiosis in France.

First evidence of Besnoitia bennetti infection (Protozoa: Apicomplexa) in donkeys (Equus asinus) in Belgium

BACKGROUND

Besnoitiosis is caused by different species of intracellular protozoan parasites belonging to the family Sarcocystidae and affecting multiple host species worldwide. Including B. besnoiti, ten species are described infecting animals. Among ungulates, Besnoitia bennetti infects horses, donkeys and zebras and was described in Africa and in the USA where donkey besnoitiosis is considered as an emerging disease.

CASE PRESENTATION

A two-year-old male donkey was purchased in May 2016 in poor body condition (cachexia, alopetic areas and pruritus mainly on neck and head) by the present owner in Le Roeulx (Belgium) from a milk producing donkey farm in Frasnes-lez-Buissenal (Belgium). Shortly after its purchase and shearing, the donkey presented with crusts, hyperkeratosis (both flanks and neck) anorexia and cachexia. A treatment with phoxim was given with no improvement. A cutaneous biopsy of hyperkeratotic skin was performed in July. It showed a perivascular eosinophilic infiltrate with a large thick walled cyst located in the dermis containing numerous bradyzoites. This was highly suggestive of besnoitiosis. Several skin biopsy samples were obtained for qPCR analysis and confirmed the presence of Besnoitia spp. DNA. Further laboratory diagnosis tests were performed (western blot and rDNA sequencing) confirming Besnoitia bennetti aetiology for the male. For the female, the punch-biopsy, haematology and qPCR were negatives but the western blot showed the presence of antibodies directed to Besnoitia spp. Further clinical examination performed in August highlighted scleral pinhead sized cysts (pearl) in the right eye and between nares. Another ten-year-old female donkey purchased in France and sharing the same accommodation showed a good clinical condition, but a thorough clinical examination showed the presence of numerous cysts on the inner face of upper labial mucosa. A daily treatment based on sulfamethaxzole and trimethoprim (Emdotrim 60% Mix®, 30 mg/kg) was given orally and some improvement was noticed.

CONCLUSION

This is the first evidence of Besnoitia bennetti infection (Protozoa: Apicomplexa) in donkeys (Equus asinus) in Belgium.

Advances in the diagnosis of bovine besnoitiosis: current options and applications for control

Bovine besnoitiosis, which is caused by the tissue cyst-forming intracellular parasite Besnoitia besnoiti, is a chronic and debilitating disease that is responsible for severe economic losses in the cattle raised under extensive husbandry systems. The absence of vaccines, treatments or a health scheme at local, national and international levels has led to a rapid spread of bovine besnoitiosis from western Europe towards eastern countries and northwards. Moreover, this parasitic disease is widely present in many sub-Saharan countries. Thus, bovine besnoitiosis should be included in the animal health scheme of beef cattle herds. Accurate diagnostic tools and common diagnostic procedures are mandatory in any control programme. Relevant advances have been made in this field during the last decade. Succeeding with accurate diagnosis relies on the technique employed and the antibody and parasite kinetics of the infection stage, which may notably influence control programmes and surveillance. Moreover, control programmes should be adapted to the epidemiological status of the disease, as the disease presentation in a herd has important implications for prospective control. Herein, we review the clinical disease presentation of bovine besnoitiosis and the correlation between its clinical course and laboratory parameters. We also provide an update on the available diagnostic tools, discuss their strengths and pitfalls, and provide guidelines for their use in control, surveillance and epidemiological studies. A rational control strategy is also recommended.

Besnoitia besnoiti lytic cycle in vitro and differences in invasion and intracellular proliferation among isolates

Background

Bovine besnoitiosis, caused by the protozoan Besnoitia besnoiti, reduces productivity and fertility of affected herds. Besnoitiosis continues to expand in Europe and no effective control tools are currently available. Experimental models are urgently needed. Herein, we describe for the first time the kinetics of standardised in vitro models for the B. besnoiti lytic cycle. This will aid to study the pathogenesis of the disease, in the screening for vaccine targets and drugs potentially useful for the treatment of besnoitiosis.

Methods

We compared invasion and proliferation of one B. tarandi (from Finland) and seven B. besnoiti isolates (Bb-Spain1, Bb-Spain2, Bb-Israel, Bb-Evora03, Bb-Ger1, Bb-France, Bb-Italy2) in MARC-145 cell culture. Host cell invasion was studied at 4, 6, 8 and 24 h post infection (hpi), and proliferation characteristics were compared at 24, 48, 72, 96, 120, and 144 hpi.

Results

In Besnoitia spp., the key parameters that determine the sequential adhesion-invasion, proliferation and egress steps are clearly distinct from those in the related apicomplexans Toxoplasma gondii and Neospora caninum. Besnoitia spp. host cell invasion is a rather slow process, since only 50 % of parasites were found intracellular after 3–6 h of exposure to host cells, and invasion still took place after 24 h. Invasion efficacy was significantly higher for Bb-France, Bb-Evora03 and Bb-Israel. In addition, the time span for endodyogeny to take place was as long as 18–35 h. Bb-Israel and B. tarandi isolates were most prolific, as determined by the tachyzoite yield at 72 hpi. The total tachyzoite yield could not be predicted neither by invasion-related parameters (velocity and half time invasion) nor by proliferation parameters (lag phase and doubling time (dT)). The lytic cycle of Besnoitia was asynchronous as evidenced by the presence of three different plaque-forming tachyzoite categories (lysis plaques, large and small parasitophorous vacuoles).

Conclusions

This study provides first insights into the lytic cycle of B. besnoiti isolates and a standardised in vitro model that allows screening of drug candidates for the treatment of besnoitiosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1405-9) contains supplementary material, which is available to authorized users.

Experimental infections of rabbits with proliferative and latent stages of Besnoitia besnoiti

Cattle besnoitiosis due to Besnoitia besnoiti is spreading across Europe and is responsible for severe economic losses in newly infected herds. Experimentally speaking, rabbits have been found to be susceptible to this parasite. The adaptation of B. besnoiti to rabbits may offer a new, easier and cheaper model of investigation for this disease. This study compared the virulence between tachyzoites and bradyzoites of B. besnoiti in rabbits. Eighteen New Zealand rabbits were allocated into three groups of six animals each. The rabbits from the control (group C), "tachyzoite" (group T) and "bradyzoite" (group B) groups were subcutaneously injected in the right flank with 66 μg of ovalbumin, 6.10(6) tachyzoites (125th passage on Vero cells) and 6.10(6) bradyzoites (collected from a natural infected cow) of B. besnoiti, respectively. Clinical follow-up and blood sampling for serological survey and qPCR were performed during 10 weeks until euthanasia. Molecular and immunohistochemistry examination was achieved on 25 samples of tissue per rabbit. Seroconversion occurred in group T without any clinical signs. Rabbits of group B exhibited a febrile condition (temperature above 40 °C from day 8 to day 11 following injection) with positive qPCR in blood. Cysts of B. besnoiti were found on skin samples and organs of rabbits from group B in tissue explored with threshold cycle (Ct) values below 30. These results suggest a higher virulence of bradyzoites in rabbits than Vero cell-cultivated tachyzoites. The proposed model could be used to assess the in vivo effectiveness of vaccine or drugs against cattle besnoitiosis.

Besnoitia besnoiti among cattle in insular and northwestern Italy: endemic infection or isolated outbreaks?

BACKGROUND

Bovine besnoitiosis, caused by the apicomplexan Besnoitia besnoiti, is a chronic and debilitating disease considered as emerging in Europe. In Spain, Portugal and France it is endemic and foci of infection were recorded in Germany, Switzerland, Hungary, Greece and Italy. In Italy, cases of bovine besnoitiosis were registered both in imported and autochthonous cattle, and mostly in central regions; high seroprevalence was also revealed by an epidemiological survey performed in the southern part of the country. Aiming to update information on the disease in northwestern and insular areas of Italy, where data on bovine besnoitiosis were missing, a serosurvey was designed for the present study.

METHODS

Three thousand one hundred and forty bovine blood samples from both dairy and beef farms (n = 126) were collected in northwestern regions (Lombardy, Piedmont and Liguria) and in the island of Sardinia. Samples were analyzed by a standardized in-house ELISA and those resulted positive were re-tested by Western Blot (WB) for confirmation. On results obtained by both ELISA and WB, apparent (AP) and true prevalence (TP) were calculated at individual and herd levels. Further, a panel of sera resulted positive to ELISA was analyzed by IFAT.

RESULTS

A total of 712 animals (AP = 22.7%; TP = 18.8%) and 109 farms (AP = 86.5%; TP = 88.2%) showed a positive reaction in ELISA. Only ten (AP = 0.3%; TP = 0%) specimens proceeding from five farms (AP = 3.9%; TP = 1.7%) from Lombardy were confirmed positive to the WB, corresponding to two Holstein Friesian cows and eight beef cattle. IFAT showed a low sensitivity (44.4%) scoring positive in only four samples out of 9 positive to WB.

CONCLUSIONS

The survey demonstrated that bovine besnoitiosis cannot still be considered endemic in whole Italy. In fact, independent foci of infection were registered only in Lombardy region. Therefore, a sanitary strategy aimed to increase control measures and to organize monitoring plans, by adequate diagnostic tools is necessary to avoid overestimation of B. besnoiti in Italy.

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.

No detection of Besnoitia besnoiti DNA in the semen of chronically infected bulls

Bovine besnoitiosis is a chronic and debilitating disease observed in many European countries that may cause important economic losses in cattle. The recent widespread of the parasite in Europe had led the European Food Safety Authority to declare bovine besnoitiosis as a re-emerging disease in Europe. Many aspects of the epidemiology of bovine besnoitiosis such as the main routes of transmission are still unclear and need to be further studied. Among the different hypotheses, a sexual transmission has not yet been investigated. Therefore, the aim of this study was to evaluate the presence of Besnoitia besnoiti DNA in the semen of naturally infected bulls by using a highly sensitive method (real-time qPCR). Both pre-sperm and sperm fractions of 40 bulls, including seronegative (n = 11), seropositive subclinically (n = 17), and seropositive clinically (n = 12) infected animals, were collected by electroejaculation and analyzed by real-time qPCR. No B. besnoiti DNA was detected in 27 pre-sperm and 28 sperm fractions of the 40 examined bulls, suggesting that the transmission of B. besnoiti infection by the semen of chronically infected bulls is very unlikely.

A review on bovine besnoitiosis: a disease with economic impact in herd health management, caused by Besnoitia besnoiti (Franco and Borges, )

Bovine besnoitiosis is caused by the largely unexplored apicomplexan parasite Besnoitia besnoiti. In cows, infection during pregnancy often results in abortion, and chronically infected bulls become infertile. Similar to other apicomplexans B. besnoiti has acquired a largely intracellular lifestyle, but its complete life cycle is still unknown, modes of transmission have not been entirely resolved and the definitive host has not been identified. Outbreaks of bovine besnoitiosis in cattle were described in the 1990s in Portugal and Spain, and later several cases were also detected in France. More cases have been reported recently in hitherto unaffected countries, including Italy, Germany, Switzerland, Hungary and Croatia. To date, there is still no effective pharmaceutical compound available for the treatment of besnoitiosis in cattle, and progress in the identification of novel targets for intervention through pharmacological or immunological means is hampered by the lack of molecular data on the genomic and transcriptomic level. In addition, the lack of an appropriate small animal laboratory model, and wide gaps in our knowledge on the host-parasite interplay during the life cycle of this parasite, renders vaccine and drug development a cost- and labour-intensive undertaking.

Transmission of pathogens by Stomoxys flies (Diptera, Muscidae): a review

Stomoxys flies are mechanical vectors of pathogens present in the blood and skin of their animal hosts, especially livestock, but occasionally humans. In livestock, their direct effects are disturbance, skin lesions, reduction of food intake, stress, blood loss, and a global immunosuppressive effect. They also induce the gathering of animals for mutual protection; meanwhile they favor development of pathogens in the hosts and their transmission. Their indirect effect is the mechanical transmission of pathogens. In case of interrupted feeding, Stomoxys can re-start their blood meal on another host. When injecting saliva prior to blood-sucking, they can inoculate some infected blood remaining on their mouthparts. Beside this immediate transmission, it was observed that Stomoxys may keep some blood in their crop, which offers a friendly environment for pathogens that could be regurgitated during the next blood meal; thus a delayed transmission by Stomoxys seems possible. Such a mechanism has a considerable epidemiological impact since it allows inter-herd transmission of pathogens. Equine infectious anemia, African swine fever, West Nile, and Rift Valley viruses are known to be transmitted by Stomoxys, while others are suspected. Rickettsia (Anaplasma, Coxiella), other bacteria and parasites (Trypanosoma spp., Besnoitia spp.) are also transmitted by Stomoxys. Finally, Stomoxys was also found to act as an intermediate host of the helminth Habronema microstoma and may be involved in the transmission of some Onchocerca and Dirofilaria species. Being cosmopolite, Stomoxys calcitrans might have a worldwide and greater impact than previously thought on animal and human pathogen transmission.

A century of bovine besnoitiosis: an unknown disease re-emerging in Europe

Bovine besnoitiosis, which is caused by the cyst-forming apicomplexan parasite Besnoitia besnoiti, is a chronic and debilitating vector-borne disease characterized by both cutaneous and systemic manifestations. In Europe, this parasitic disease appeared in a few restricted areas in France and Portugal since the first recorded cases in the beginning of the 20th century. However, at present, the disease is considered to be re-emerging by the European Food Safety Authority due to an increased number of cases and the geographic expansion of besnoitiosis into cattle herds in several European countries. In this review, we will provide an update of the epidemiology and impact of B. besnoiti infection. Strategies to control this parasitic disease will also be discussed.

The repellency of lemongrass oil against stable flies, tested using video tracking

Lemongrass oil (Cymbopogon citratus) is an effective repellent against mosquitoes (Diptera: Culicidae) and house flies (Diptera: Muscidae). In this study, its effectiveness was assessed on stable flies (Diptera: Muscidae) in laboratory conditions. First, we demonstrated that lemongrass oil is an active substance for antennal olfactory receptor cells of Stomoxys calcitrans as indicated by a significant increase in the electroantennogram responses to increasing doses of lemongrass oil. Feeding-choice tests in a flight cage with stable flies having access to two blood-soaked sanitary pads, one of which was treated with lemongrass oil, showed that stable flies (n = 24) spent significantly more time in the untreated zone (median value = 218.4 s) than in the treated zone (median value = 63.7 s). No stable flies fed on the treated pad, whereas nine fed on the untreated pad. These results suggest that lemongrass oil could be used as an effective repellent against stable flies. Additional studies to confirm its spatial repellent and feeding deterrent effects are warranted.