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Dargatz, D. A., & Traub-Dargatz, J. L. (2004). Multidrug-resistant Salmonella and nosocomial infections. Vet Clin North Am Equine Pract, 20(3), 587–600.
Abstract: Nosocomial infections are a serious threat to optimum patient care. In addition, nosocomial infections can have far-reaching consequences for the hospital personnel and the financial aspects of the hospital. Nosocomial infections with Salmonella spp have been described among hospitalized equine populations more frequently than any other agent. Salmonella spp associated with hospitalized equids often possess more antimicrobial resistance determinants than do Salmonella spp isolated from healthy horses in the general population. There is little evidence to suggest that resistant salmonellae are more virulent than nonresistant forms. MDR forms of Salmonella complicate the selection of appropriate antimicrobials when they are indicated, however. Furthermore, the use of some antimicrobials may apply selection pressure toward enhanced ability of MDR Salmonella to colonize equine patients. Further research should help to elucidate the risky uses of antimicrobials in the hospital setting and define the role of disinfectants and treatments such as NSAIDs in the ecology of MDR forms of nosocomial infections, including Salmonella. In the meantime, thoughtful selection of when and how to use antimicrobials in equine patients, together with deliberate selection of which antimicrobials to use based on monitoring data and other factors, such as safety and spectrum, is advised.
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Giangaspero, A., Traversa, D., & Otranto, D. (2004). [Ecology of Thelazia spp. in cattle and their vectors in Italy]. Parassitologia, 46(1-2), 257–259.
Abstract: The genus Thelazia (Spirurida, Thelaziidae) includes a cosmopolitan group of eyeworm spirurids responsible for ocular infections in domestic and wild animals and transmitted by different species of muscids. Bovine thelaziosis is caused by Thelazia rhodesi Desmarest 1828, Thelazia gulosa Railliet & Henry 1910, and Thelazia skrjabini Erschow 1928, which occur in many countries; T. gulosa and T. skrjabini have been reported mainly in the New World, while T. rhodesi is particularly common in the Old World. In Italy, T. rhodesi was reported in southern regions a long time ago and, recently, T. gulosa and T. skrjabini have been identified in autochthonous cattle first in Apulia and then in Sardinia. Thirteen species of Musca are listed as intermediate hosts of eyeworms, but only Musca autumnalis and Musca larvipara have been demonstrated to act as vectors of Thelazia in the ex-URSS, North America, ex-Czechoslovakia and more recently in Sweden. In Italy, after the reports of T. gulosa and T. skrjabini in southern regions, the intermediate hosts of bovine eyeworms were initially only suspected as the predominant secretophagous Muscidae collected from the periocular region of cattle with thelaziosis were the face flies, M. autumnalis and M. larvipara, followed by Musca osiris, Musca tempestiva and Musca domestica. The well-known constraints in the identification of immature eyeworms to species by fly dissection and also the time-consuming techniques used constitute important obstacles to epidemiological field studies (i.e. vector identification and/or role, prevalence and pattern of infection in flies, etc.). Molecular studies have recently permitted to further investigations into this area. A PCR-RFLP analysis of the ribosomal ITS-1 sequence was developed to differentiate the 3 species of Thelazia (i.e. T. gulosa, T. rhodesi and T. skrjabini) found in Italy, then a molecular epidemiological survey has recently been carried out in field conditions throughout five seasons of fly activity and has identified the role of M. autumnalis, M. larvipara, M. osiris and M. domestica as vectors of T. gulosa and of M. autumnalis and M. larvipara of T. rhodesi. Moreover, M. osiris was described, for the first time, to act as a vector of T. gulosa and M. larvipara of T. gulosa and T. rhodesi. The mean prevalence in the fly population examined was found to be 2.86%. The molecular techniques have opened new perspectives for further research on the ecology and epidemiology not only of Thelazia in cattle but also of other autochthonous species of Thelazia which have been also recorded in Italy, such as Thelazia callipaeda, which is responsible for human and canid ocular infection and Thelazia lacrymalis, the horse eyeworm whose epidemiological molecular studies are in progress.
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Traversa, D., Giangaspero, A., Galli, P., Paoletti, B., Otranto, D., & Gasser, R. B. (2004). Specific identification of Habronema microstoma and Habronema muscae (Spirurida, Habronematidae) by PCR using markers in ribosomal DNA. Mol Cell Probes, 18(4), 215–221.
Abstract: Gastric or cutaneous habronemosis caused by Habronema microstoma Creplin, 1849 and Habronema muscae Carter, 1865 is a parasitic disease of equids transmitted by muscid flies. There is a paucity of information on the epidemiology of this disease, which is mainly due to limitations with diagnosis in the live animal and with the identification of the parasites in the intermediate hosts. To overcome such limitations, a molecular approach, based on the use of genetic markers in the second internal transcribed spacer (ITS-2) of ribosomal DNA, was established for the two species of Habronema. Characterisation of the ITS-2 revealed sequence lengths and G+C contents of 296 bp and 29.5% for H. microstoma, and of 334 bp and 35.9% for H. muscae, respectively. Exploiting the sequence difference (approximately 40%) between the two species of nematode, primers were designed and tested by the polymerase chain reaction (PCR) for their specificity using a panel of control DNA samples from common equid endoparasites, and from host tissues, faeces or muscid flies. Effective amplification from each of the two species of Habronema was achieved from as little as 10 pg of genomic DNA. Hence, this molecular approach allows the specific identification and differentiation of the DNA from H. microstoma and H. muscae, and could thus provide a molecular tool for the specific detection of Habronema DNA (irrespective of developmental stage) from faeces, skin and muscid fly samples. The establishment of this tool has important implications for the specific diagnosis of clinical cases of gastric and cutaneous habronemosis in equids, and for studying the ecology and epidemiology of the two species of Habronema.
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Dauphin, G., Zientara, S., Zeller, H., & Murgue, B. (2004). West Nile: worldwide current situation in animals and humans. Comp Immunol Microbiol Infect Dis, 27(5), 343–355.
Abstract: West Nile (WN) virus is a mosquito-borne flavivirus that is native to Africa, Europe, and Western Asia. It mainly circulates among birds, but can infect many species of mammals, as well as amphibians and reptiles. Epidemics can occur in rural as well as urban areas. Transmission of WN virus, sometimes involving significant mortality in humans and horses, has been documented at erratic intervals in many countries, but never in the New World until it appeared in New York City in 1999. During the next four summers it spread with incredible speed to large portions of 46 US states, and to Canada, Mexico, Central America and the Caribbean. In many respects, WN virus is an outstanding example of a zoonotic pathogen that has leaped geographical barriers and can cause severe disease in human and equine. In Europe, in the past two decades there have been a number of significant outbreaks in several countries. However, very little is known of the ecology and natural history of WN virus transmission in Europe and most WN outbreaks in humans and animals remain unpredictable and difficult to control.
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Nelson, D. M., Gardner, I. A., Chiles, R. F., Balasuriya, U. B., Eldridge, B. F., Scott, T. W., et al. (2004). Prevalence of antibodies against Saint Louis encephalitis and Jamestown Canyon viruses in California horses. Comp Immunol Microbiol Infect Dis, 27(3), 209–215.
Abstract: Jamestown Canyon (JC) and Saint Louis encephalitis (SLE) viruses are mosquito-transmitted viruses that have long been present in California. The objective of this study was to determine the seroprevalence of these two viruses in horses prior to the introduction of West Nile (WN) virus. Approximately 15% of serum samples collected in 1998 from 425 horses on 44 equine operations horses throughout California had serum antibodies to JC virus, whereas antibodies were not detected to SLE virus. The results indicate that horses in California were commonly infected prior to 1998 with mosquito-transmitted Bunyaviruses that are identical or closely related to JC virus, but not with SLE virus. The different seroprevalence of SLE and JC viruses in horses likely reflects the unique ecology of each virus, and it is predicted that WN virus will have a wider distribution in California than closely related SLE virus.
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Komar, N. (2003). West Nile virus: epidemiology and ecology in North America. Adv Virus Res, 61, 185–234.
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Passler, S., & Pfeffer, M. (2003). Detection of antibodies to alphaviruses and discrimination between antibodies to eastern and western equine encephalitis viruses in rabbit sera using a recombinant antigen and virus-specific monoclonal antibodies. J Vet Med B Infect Dis Vet Public Health, 50(6), 265–269.
Abstract: Three arthropod-borne alphaviruses, western equine encephalitis viruses (WEEV), eastern equine encephalitis viruses (EEEV) and Venezuelan equine encephalitis viruses are the aetiological agents of a sometimes severe encephalomyelitis in equines and humans in the New World. With regard to the different ecology and epidemiology of these viruses, a method applied in serological screening should be able to distinguish between them as well as other related members of the genus Alphavirus in the American continent. However, this has been hampered in the past by (a) the close antigenic relationship between alphaviruses in traditional serological assays, especially in the routinely used haemagglutination-inhibition, and (b) the need of biosafety level 3 facilities to grow the viral antigens. An epitope blocking assay using an EEEV glycoprotein E1-expressing recombinant Sindbis virus and virus-specific monoclonal antibodies (mAbs) binding to the E1 of EEEV (strain NJ/60) and the E1 of Sindbis virus was established using automated flow cytometry. The test was evaluated using sera of infected and vaccinated rabbits. A cut-off value of 30% inhibition for antigenic complex-specific seroconversion was found to be sufficient for the detection of the respective infection. By using three different mAbs in parallel, we were able to detect alphavirus genus-, EEEV- and WEEV-complex-specific serum antibodies. As this test is based on the inhibition of binding of virus-specific mAbs, sera of every origin other than mouse can be tested. Thus, this assay may prove useful in the serological screening of a variety of animal species during an outbreak investigation.
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Barker, S. C. (2003). The Australian paralysis tick may be the missing link in the transmission of Hendra virus from bats to horses to humans. Med Hypotheses, 60(4), 481–483.
Abstract: Hendra virus is a new virus of the family Paramyxoviridae. This virus was first detected in Queensland, Australia, in 1994; although, it seems that the virus has infected fruit-eating bats (flying-foxes) for a very long time. At least 2 humans and 15 horses have been killed by this virus since it first emerged as a virus that may infect mammals other than flying-foxes. Hendra virus is thought to have moved from flying-foxes to horses, and then from horses to people. There is a reasonably strong hypothesis for horse-to-human transmission: transmission of virus via nasal discharge, saliva and/or urine. In contrast, there is no strong hypothesis for flying-fox-to-human transmission. I present evidence that the Australian paralysis tick, Ixodes holocyclus, which has apparently only recently become a parasite of flying-foxes, may transmit Hendra virus and perhaps related viruses from flying-foxes to horses and other mammals.
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Hall, R. A., Broom, A. K., Smith, D. W., & Mackenzie, J. S. (2002). The ecology and epidemiology of Kunjin virus. Curr Top Microbiol Immunol, 267, 253–269.
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Endy, T. P., & Nisalak, A. (2002). Japanese encephalitis virus: ecology and epidemiology. Curr Top Microbiol Immunol, 267, 11–48.
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