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What do we still need to know about Ixodes ricinus?

2021-05, Gray, J. (Jeremy S.), Kahl, Olaf, Zintl, Annetta

In spite of many decades of intensive research on Ixodes ricinus, the castor bean tick of Europe, several important aspects of its basic biology remain elusive, such as the factors determining seasonal development, tick abundance and host specificity, and the importance of water management. Additionally, there are more recent questions about the geographical diversity of tick genotypes and phenotypes, the role of migratory birds in the ecoepidemiology of I. ricinus, the importance of protective immune responses against I. ricinus, particularly in the context of vaccination, and the role of the microbiome in pathogen transmission. Without more detailed knowledge of these issues, it is difficult to assess the likely effects of changes in climate and biodiversity on tick distribution and activity, to predict potential risks arising from new and established tick populations and I. ricinus-borne pathogens, and to improve prevention and control measures. This review aims to discuss the most important outstanding questions against the backdrop of the current state of knowledge of this important tick species.

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Changing incidence of bovine babesiosis in Ireland

2014-09-05, Zintl, Annetta, McGrath, Guy, O'Grady, Luke, Gray, J. (Jeremy S.), et al.

Background: In Ireland bovine babesiosis is caused by the tick-borne blood parasite, Babesia divergens. A survey of veterinary practitioners and farmers in the 1980’s revealed an annual incidence of 1.7% associated with considerable economic losses. However, two subsequent surveys in the 1990’s indicated a decline in clinical babesiosis. Recent evidence from continental Europe suggests that, probably due to climate change, the distribution of the tick vector of B. divergens, Ixodes ricinus is extending to more northerly regions and higher altitudes. In addition, milder winters are thought to widen the window of tick activity. In order to determine whether any such changes have affected the incidence of bovine babesiosis in Ireland, a questionnaire survey of farmers and veterinarians was carried out and compared with data from previous surveys. Results: Our survey indicates that while the incidence of clinical disease has continued to decline, cases can occur at any time of year. In contrast to previous surveys, affected farms were the same size as unaffected ones. There was no correlation between disease risk and the presence of deer on the land. Disease severity and mortality rates were increased because many infections were advanced by the time they were detected and treated. Conclusion: While the precise reasons for the decline in the incidence of redwater are unknown, changes in agricultural practice are likely to be of importance. A reversal of the trend could be devastating, as vigilance among farmers and veterinarians is flagging and the national herd is losing its protective immunity to disease.

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Squirrelpox virus reservoir expansion on the east coast of Ireland

2015-03-03, Stritch, Carin, Naulty, Favel, Zintl, Annetta, Callanan, John J., Mccullough, Maureen, McMahon, Barry J., et al.

The European red squirrel (Sciurus vulgaris) has suffered a 20 % decline in range in Ireland since the introduction of the eastern grey squirrel (Sciurus carolinensis) in 1911. In the UK, squirrelpox virus (SQPV) has been identified as being a major contributor to the decline of red squirrel populations but has only recently been confirmed in a red squirrel from Wicklow in Ireland with anecdotal references to a previous outbreak in the Shankill area of south County Dublin and a case in Kilmacanogue, north County Wicklow. The current study examined a sample of grey squirrels from these areas for SQPV seroprevalence. Enzyme-linked immunosorbent assay (ELISA) tests were carried out on sera from 51 grey squirrels culled from two sites in south County Dublin, areas A and B, and a third site in north County Wicklow, area C. The results indicated declining SQPV seroprevalence rates moving northwards from Wicklow, 55 % in area C, 50 % in area B and 11 % in area A. The low levels of seropositivity in Killiney (A) suggest that this is the wave-front of grey squirrel expansion from Wicklow and that the population may not yet have reached the threshold density for SQPV transmission to the red squirrel population to occur. The results of this study indicate that there is potential overlap between seropositive grey squirrel populations and susceptible red squirrel populations with obvious implications for conservation and management.

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Comparison of in vitro viability methods for Cryptosporidium oocysts

2018-04, Vande Burgt, Nathan H., Auer, Agathe, Zintl, Annetta

The water-borne protozoan parasite Cryptosporidium parvum forms oocysts that can persist for long periods of time in the environment, even though the sporozoites inside the oocysts may no longer be viable, making it difficult to assess the associated risk of infection. In this study, we compared the ability of various in vitro methods to discriminate viable from non-viable oocysts, including excystation, DAPI/PI staining, RNA FISH, PMA-qPCR and a novel polymer slide adhesion method. With the notable exception of our in vitro excystation protocol, all methods were found to be useful for identifying viable oocysts.

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Update on the presence of Ixodes ricinus at the western limit of its range and the prevalence of Borrelia burgdorferi sensu lato

2020-11, Zintl, Annetta, Zaid, Taher M.T., McKiernan, Fiona, Naranjo Lucena, Amalia, Gray, J. (Jeremy S.), Brosnan, Sorcha, Browne, John, et al.

It is often suggested that due to climate and environmental policy changes, the risk from tick-borne disease is increasing, particularly at the geographical limits of the vector distribution. Our project aimed to determine whether this was true for the risk of Lyme borreliosis in Ireland which is the western-most limit of Ixodes ricinus, the European vector of Borrelia burgdorferi sensu lato. The availability of a historical data set of tick infection rates compiled in the 1990s represented a unique opportunity as it provided a baseline against which current data could be compared. Following construction of a spatial predictive model for the presence and absence of I. ricinus based on data from 491 GPS locations visited between 2016 and 2019, 1404 questing nymphs from 27 sites were screened for the presence of Borrelia spp. using a TaqMan PCR aimed at the 23S rRNA gene sequence. All positive ticks were further analysed by nested PCR amplification and sequence analysis of the 5 S–23 S intergenic spacer. The model indicated that areas with the highest probability of tick presence were mostly located along the western seaboard and the Shannon and Erne river catchments, coinciding with historical high incidence areas of bovine babesiosis, while the infection rate of questing nymphs with B. burgdorferi s.l. and the prevalence of the various genospecies have remained surprisingly stable over the last 3 decades. Clear communication of the potential disease risk arising from a tick bite is essential in order to allay undue concerns over tick-borne diseases among the general public.

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Comparison of diagnostic techniques for the detection of Cryptosporidium oocysts in animal samples

2015-05, Mirhashemi, Marzieh Ezzaty, Zintl, Annetta, Grant, Tim, Lucy, Frances E., Mulcahy, Grace, De Waal, Theo

While a large number of laboratory methods for the detection of Cryptosporidium oocysts in faecal samples are now available, their efficacy for identifying asymptomatic cases of cryptosporidiosis is poorly understood. This study was carried out to determine a reliable screening test for epidemiological studies in livestock. In addition, three molecular tests were compared to identify Cryptosporidium species responsible for the infection in cattle, sheep and horses. A variety of diagnostic tests including microscopic (Kinyoun's staining), immunological (Direct Fluorescence Antibody tests or DFAT), enzyme-linked immunosorbent assay (ELISA), and molecular methods (nested PCR) were compared to assess their ability to detect Cryptosporidium in cattle, horse and sheep faecal samples. The results indicate that the sensitivity and specificity of each test is highly dependent on the input samples; while Kinyoun's and DFAT proved to be reliable screening tools for cattle samples, DFAT and PCR analysis (targeted at the 18S rRNA gene fragment) were more sensitive for screening sheep and horse samples. Finally different PCR primer sets targetedat the same region resulted in the preferential amplification of certain Cryptosporidium species when multiple species were present in the sample. Therefore, for identification of Cryptosporidium spp. in the event of asymptomatic cryptosporidiosis, the combination of different 18S rRNA nested PCR primer sets is recommended for further epidemiological applications and also tracking the sources of infection.

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Bulk milk ELISA and the diagnosis of parasite infections in dairy herds: A review

2013-07-25, Sekiya, Mary, Zintl, Annetta, Doherty, Michael L.

The bulk milk enzyme-linked immune sorbent assay (ELISA) is a rapid and inexpensive method of assessing herd exposure to pathogens that is increasingly being used for the diagnosis of parasite infections in dairy herds. In this paper, with the dairy herd health veterinarian in mind, we review the principles of the assay and the recent literature on the potential role of bulk milk ELISA for the diagnosis of ostertagiosis, fasciolosis, parasitic bronchitis due to cattle lung worm and neosporosis. It is generally accepted that assay results reflect exposure to the parasite rather than the presence of active infection. Bulk milk ELISA can be a useful tool for the veterinary practitioner as a component of a herd health monitoring programme or in the context of a herd health investigation. It can also play a role in regional or national surveillance programmes. However, the results need to be interpreted within the context of the herd-specific health management, the milk production pattern and the parasite life cycle.

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The immunoregulatory effects of co-infection with Fasciola hepatica: From bovine tuberculosis to Johne's disease

2017-04, Naranjo Lucena, Amalia, Garza-Cuartero, Laura, Mulcahy, Grace, Zintl, Annetta

Fasciola hepatica (liver fluke) is a parasite prevalent in much of the world that causes the economically-important disease of fasciolosis in livestock. The threat that this disease poses extends beyond its direct effects due to the parasite's immunomodulatory effects. Research at this laboratory is focusing on whether this immunoregulation can, in animals infected with liver fluke, exert a bystander effect on concurrent infections in the host. It has already been established that F. hepatica infection reduces cell mediated immune responses to Mycobacterium bovis in cattle, and that the interaction between the two pathogens can be detected on an epidemiological scale. This review explores the immunological consequences of co-infection between F. hepatica and other bacterial infections. Arguments are presented suggesting that immunity of cattle to Mycobacterium avium subsp. paratuberculosis is also likely to be affected.

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A Survey of Ticks Infesting Dogs and Cats in Ireland

2020-08-12, De Waal, Theo, Lawlor, Amanda, Zintl, Annetta, Cowley, D. J. Bosco, Bagha, Atiyah

Ticks are important ectoparasites of dogs and cats. Infestations can result in itching and localised dermatitis. In addition, ticks can act as vector of a range of viral, bacterial and protozoal pathogens. This paper reports the results of a nationwide survey of ticks infesting dogs and cats in Ireland. Seventy veterinary practices submitted a total of 120 ticks collected from 56 dogs and 16 cats. Ixodes ricinus was the most abundant species on dogs while Ixodes hexagonus was the most abundant species on cats. The remainder were identified as Ixodes canisuga and a single Rhipicephalus sanguineus specimen. The garden was most frequently associated with tick exposure in both dogs and cats. Sporting dog breeds (n = 17; 31%) were more likely to be infested with ticks than any other breed. Nearly all (n = 56; 95%) veterinarians indicated that ticks are a concern to their clients when they are found on their pets. Pet owners used a variety of products to control ectoparasites on their animals but a significant number (n = 18, 31%) indicated that they felt that the products are less effective highlighting the need for further investigations. Field sampling indicated that ticks are present at a low level in much of the greater Dublin area.

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Comparison of three methods for the detection of Angiostrongylus vasorum in the final host

2016-04-15, Houpin, E., McCarthy, Grainne, Ferrand, M., De Waal, Theo, O'Neill, Emma J., Zintl, Annetta

Angiostrongylosis is potentially fatal parasitic nematode infection affecting dogs which can be difficult to diagnose. In recent years several microscopical, serological and molecular detection methods have been developed, however there are few studies that have compared the relative performance of these methods. Screening necropsy material from an opportunistic sample of 140 foxes (82 of which were considered to be infected with Angiostrongylus vasorum), indicated sensitivities of 84.1% for dissection and visual examination of plucks, 69.5% for nested PCR of an 18S rRNA fragment and 76.8% for a canine A. vasorum antigen detection test (IDEXX Angio Detect) of tissue fluid samples respectively. Agreement between the tests ranged from 45.6 to 79.7%. A novel nested PCR-RFLP for the detection and identification of canid lungworm spp. is described.