Assessment of mycoplasma vaccine efficacy in reducing infection with Newcastle disease virus

The present work recorded the impact of using Mycoplasma gallisepticum vaccines on post-vaccinal response and protection against challenge with Newcastle disease virus. Specific pathogen-free chickens were divided into eight groups of forty chickens each. Group G1 was vaccinated with Mycoplasma gallisepticum live attenuated and Mycoplasma gallisepticum inactivated vaccines. Group G2 was vaccinated with Mycoplasma gallisepticum live attenuated, Mycoplasma gallisepticum inactivated and Newcastle disease inactivated vaccines. Group G3 was vaccinated with Mycoplasma gallisepticum live attenuated vaccine. Group G4 was vaccinated with Mycoplasma gallisepticum live attenuated and Newcastle disease inactivated vaccines. Group G5 was vaccinated with Mycoplasma gallisepticum inactivated vaccine. Group G6 was vaccinated with Mycoplasma gallisepticum inactivated and Newcastle disease inactivated vaccines. Group G7 was vaccinated with Newcastle disease inactivated vaccine. Group G8 was kept as non-vaccinated control. The Newcastle disease hemagglutination inhibition antibodies and mortality percentages were measured. Group G7 recorded the best protective Newcastle disease hemagglutination inhibition antibody titer (7 log2). Group G2 recorded a marginal satisfactory antibody titer (6 log2) after vaccination by the three tested vaccines. The remaining groups revealed unsatisfactory titers ranged from 0-5. The protection levels for G2, G4, G6 and G7 ranged from 70percent to 100percent, but only G2 and G7 were considered protected. G1, G3, G5 and G8 showed typical clinical signs of Newcastle disease. The Mycoplasma gallisepticum vaccines couldn't improve the response to Newcastle disease inactivated vaccine. The results suggest that Mycoplasma gallisepticum vaccination is immunosuppressive rather than immunomodulatory in Newcastle disease vaccination(AU)

En el presente trabajo se registró el impacto de la utilización de vacunas contra Mycoplasma gallisepticum sobre la respuesta posvacunal y la protección frente al reto con el virus de la enfermedad de Newcastle. Pollos libres de patógenos específicos se distribuyeron en ocho grupos de cuarenta pollos cada uno. El grupo G1 se vacunó con vacunas vivas atenuadas e inactivadas contra Mycoplasma gallisepticum. Al grupo G2 se le aplicaron las vacunas: viva atenuada contra Mycoplasma gallisepticum, inactivada contra Mycoplasma gallisepticum e inactivada contra la enfermedad de Newcastle. El grupo G3 se inmunizó con la vacuna viva atenuada contra Mycoplasma gallisepticum; el G4, con las vivas atenuadas contra Mycoplasma gallisepticum e inactivada contra la enfermedad de Newcastle; el G5, con la vacuna inactivada contra Mycoplasma gallisepticum; el G6 con las vacunas inactivadas contra Mycoplasma gallisepticum y la enfermedad de Newcastle; el G7, con la vacuna inactivada contra la enfermedad de Newcastle y el G8 se mantuvo como control no vacunado. Se midieron los anticuerpos de inhibición de la hemaglutinación contra el virus de la enfermedad de Newcastle y los porcentajes de mortalidad. El grupo G7 registró el mejor título de anticuerpos inhibidores de la hemaglutinación contra la enfermedad de Newcastle (7 log2). El grupo G2 registró un título de anticuerpos marginalmente satisfactorio (6 log2) tras la vacunación con las tres vacunas ensayadas. Los demás grupos revelaron títulos insatisfactorios que oscilaban entre 0 y 5. Los niveles de protección de los grupos G2, G4, G6 y G7 oscilaron entre el 70 por ciento y el 100 por ciento, pero sólo G2 y G7 se consideraron protegidos. Los grupos G1, G3, G5 y G8 mostraron signos clínicos típicos de la enfermedad de Newcastle. Las vacunas contra Mycoplasma gallisepticum no pudieron mejorar la respuesta a la vacuna inactivada contra la enfermedad de Newcastle. Los resultados revelan que la vacunación con Mycoplasma gallisepticum es más inmunosupresora que inmunomoduladora en la vacunación contra la enfermedad de Newcastle(AU)

Multilocus sequence typing of pathogenic Mycoplasma mycoides subsp. capri reveals the predominance of a novel clonal complex among isolates from goats in India.

Mycoplasma mycoides subsp. capri (Mmc) typically causes pneumonia, mastitis, arthritis, keratitis and septicaemia in goats. Mortality associated with Mmc in goat flocks is lower compared to Mycoplasma capricolum subsp. capripneumoniae-associated respiratory infections. Case fatality rates associated with Mmc ranged from 9.8 to 26.8% among several states in India. Molecular epidemiology approaches aimed at genotyping help to identify the diversity of isolates involved in a disease. Ten clinical pathogenic Mmc isolates were analysed by multilocus sequence typing (MLST) for studying genotypic relationships with 50 isolates available from public databases. The MLST analysis indicates high genetic diversity among Mmc isolates. From a total number of 60 isolates, 43 six sequence types (STs) were recognized comprising of six STs from India and 37 STs from other geographical regions. MLST profiles of isolates revealed none of the STs observed in Indian isolates were shared with global isolates. Some of the STs representing Indian isolates (four STs) were clustered into a novel clonal complex 1 (CC1). Maintenance of genetically related STs forming CCs among the goat population in India for longer periods indicates disease causing potentiality of these isolates. Based on various recombination analysis, weak clonal relationship among Mmc isolates were identified. The present study has enlightened further steps in disease investigations and to design future control measures by employing prevalent genotypes as vaccine candidates against Mmc infections.

Pathogenic load and frailty in older adults: Singapore longitudinal ageing study.

Human evidence for the role of continuous antigenic stimulation from persistent latent infections in frailty is limited. We conducted a nested case-control study (99 deceased and 43 survivors) of participants aged 55 and above in a longitudinal ageing cohort followed up from 2003 to 2017. Using blood samples and baseline data collected in 2003-2004, we examined the association of pathogenic load (PL) count of seropositivity to 10 microbes (viruses, bacteria and mycoplasma) with cumulated deficit-frailty index (CD-FI) and the physical frailty (PF) phenotype, and mortality. Controlling for age, sex, education, smoking and alcohol histories, high PL (7-9) versus low PL (3-6) was associated with an estimated increase of 0.035 points in the CD-FI (Cohen's D=0.035 / 0.086, or 0.41). High PL was associated with 8.5 times odds of being physically frail (p=0.001), 2.8 times odds of being weak (p=0.010), 3.4 times odds of being slow (p=0.024), and mortality hazard ratio of 1.53 (p=0.046). There were no significant associations for specific pathogens, except marginal associations for Epstein-Barr virus and Chikungunya. Conclusion: A high pathogenic load of latent infections was associated with increased risks of frailty and mortality.

Increased incidence rate of undesired early heifer departure in Mycoplasma bovis-antibody positive Danish dairy cattle herds.

Mycoplasma bovis infections cause disease and production losses in cattle worldwide. The long-term consequences are not well described despite being important for management decisions during and after disease outbreaks. We investigated the association between M. bovis antibody-positivity and undesired early departure (UED, i.e. death, euthanasia or slaughter) before first calving in a cohort of 636 heifers from 36 Danish dairy herds with and without a history of M. bovis-associated disease. The herds were visited 4 times at 3-month intervals and blood samples from young stock and milk samples from lactating cows were collected. Poisson regression was performed to examine the association with UED as outcome, logarithmic transformation of risk time as offset and herd as a random effect. Individual antibody measurements and group-level variables representing the infection level among young stock and cows, age and mortality variables were included in the model. The incidence rate ratio of UED increased by 1.23 times for every 10% increase in M. bovis young stock seroprevalence, while the effect of individual antibody level was modified by age and influenced UED less. In conclusion, UED in heifers was associated with M. bovis antibody-positivity in young stock and should be controlled in dairy herds to reduce losses.

Patho-bacteriological investigation of an outbreak of Mycoplasma bovis infection in calves - Emerging stealth assault.

Mycoplasma bovis (M. bovis) is an important bacterium, causing severe respiratory infection, and arthritis in dairy animals worldwide. This study is based on 50 suckling calves among which 15 showed respiratory distress, lameness and swollen joints and died later. M. bovis was isolated and identified from all dead (n = 15) and live (17.14%; 06 out of 35) calves on the basis of bacteriological examination. In morbid calves, the carpus and stifle joints were severely affected, while necropsy revealed multiple well-circumscribed calcified abscesses and caseous exudates in cranio-ventral and diaphragmatic lobes of lungs. Suppurative polyarthritis, fibrino-suppurative, teno-synovitis and otitis media were the common and striking lesion observed at postmortem examination. Histopathological examination revealed broncho-interstitial pneumonia and necrotic fibrino-purulent broncho-pneumonia in lungs. Similarly, synovial membranes and joints revealed presence of multiple foci of liquefactive necrosis surrounded by lymphocytes, plasma cells, macrophages and peripheral fibroplasia. In the bacteriological investigations, the characteristic fried egg colonies of M. bovis further confirmed this infection in all suspected cases. In conclusion, the current clinico-histo-pathological features are the depictive picture, and is the first report of M. bovis infection in calves in Pakistan.

Fatal nosocomial meningitis caused by Mycoplasma hominis in an adult patient: case report and review of the literature.

Meningitis due to Mycoplasma hominis in adults is rarely described, with only three cases having been reported to date. A case of fatal meningitis in a 39-year-old patient after a neurosurgical procedure for a subarachnoid haemorrhage is reported herein. Identification and treatment were significantly delayed because of the rarity of the aetiology and difficulty identifying this organism with the routinely used conventional methods, such as Gram staining and agar growth on standard agar plates. Clinical procedures and the treatment of 'culture-negative' central nervous system infections is a real challenge for clinical microbiologists and clinicians, and M. hominis has to be considered as a potential, although very uncommon, pathogen.

A new predilection site of Mycoplasma bovis: Postsurgical seromas in beef cattle.

Mycoplasma bovis is a highly contagious bacterium, which predominantly causes chronic pneumonia, otitis and arthritis in calves and mastitis in adult cattle. In humans, Mycoplasma species have been associated with post-surgical infections. The present study aimed to identify the bacteria associated with three outbreaks of infected seromas after caesarian section in Belgian Blue beef cattle. A total of 10 cases occurred in three herds which were in close proximity of each other and shared the same veterinary practice. M. bovis could be cultured from seroma fluid in five of the six referred animals, mostly in pure culture and was isolated from multiple chronic sites of infection (arthritis and mastitis) as well. DNA fingerprinting of the isolates targeting two insertion sequence elements suggested spread of M. bovis from chronic sites of infection (udder and joints) to the postsurgical seromas. Identical genetic profiles were demonstrated in two animals from two separate farms, suggesting spread between farms. Mortality rate in the referred animals positive for M. bovis in a seroma was 80% (4/5), despite intensive treatment. A massive increase in antimicrobial use was observed in every affected farm. These observations demonstrate involvement of mycoplasmas in outbreaks of postsurgical seromas in cattle.

First isolation of Mycoplasma iowae in grey partridge flocks.

Mycoplasma iowae, an occasional pathogen of turkeys, was isolated for the first time from captive grey partridges (Perdix perdix). Clinical signs including respiratory and intestinal disorder were seen in birds of all ages but mainly in those kept housed during rearing. Mortality rates averaged over 20% during the year. Treatment with antibiotics and antiparasitic drugs produced only a transient improvement in condition. The gross pathology findings included poor body growth, lack of development of the breast muscles, abnormalities in the keel development, and bone fragility. Some birds showed infraorbital sinusitis with serous or fibrinous exudates and catarrhal tracheitis, while others presented serofibrinous airsacculitis and splenomegaly. Laboratory investigations revealed pure cultures of M. iowae in the gut as well as sinus and air sacs. While other organisms such as coccidia, Trichomonas, Escherichia coli, Clostridium perfringens, and Aspergillus spp. were detected, the similarity of the disease with that seen in turkeys infected with M. iowae strongly suggests that this mycoplasma may be the primary pathogen here. The presence of M. iowae in game birds commonly released into the wild could have serious implications particularly in areas where industrial poultry farms are concentrated.

Hemotropic mycoplasmas in little brown bats (Myotis lucifugus).

BACKGROUND: Hemotropic mycoplasmas are epicellular erythrocytic bacteria that can cause infectious anemia in some mammalian species. Worldwide, hemotropic mycoplasmas are emerging or re-emerging zoonotic pathogens potentially causing serious and significant health problems in wildlife. The objective of this study was to determine the molecular prevalence of hemotropic Mycoplasma species in little brown bats (Myotis lucifugus) with and without Pseudogymnoascus (Geomyces) destrucans, the causative agent of white nose syndrome (WNS) that causes significant mortality events in bats. METHODS: In order to establish the prevalence of hemotropic Mycoplasma species in a population of 68 little brown bats (Myotis lucifugus) with (n = 53) and without (n = 15) white-nose syndrome (WNS), PCR was performed targeting the 16S rRNA gene. RESULTS: The overall prevalence of hemotropic Mycoplasmas in bats was 47%, with similar (p = 0.5725) prevalence between bats with WNS (49%) and without WNS (40%). 16S rDNA sequence analysis (~1,200 bp) supports the presence of a novel hemotropic Mycoplasma species with 91.75% sequence homology with Mycoplasma haemomuris. No differences were found in gene sequences generated from WNS and non-WNS animals. CONCLUSIONS: Gene sequences generated from WNS and non-WNS animals suggest that little brown bats could serve as a natural reservoir for this potentially novel Mycoplasma species. Currently, there is minimal information about the prevalence, host-specificity, or the route of transmission of hemotropic Mycoplasma spp. among bats. Finally, the potential role of hemotropic Mycoplasma spp. as co-factors in the development of disease manifestations in bats, including WNS in Myotis lucifugus, remains to be elucidated.

Cathepsin L protects mice from mycoplasmal infection and is essential for airway lymphangiogenesis.

Cathepsin L (Ctsl) is a proposed therapeutic target to control inflammatory responses in a number of disease states. However, Ctsl is thought to support host defense via its involvement in antigen presentation pathways. Hypothesizing that Ctsl helps combat bacterial infection, we investigated its role in Mycoplasma pulmonis-infected mice as a model of acute and chronic infectious airway inflammation. Responses to the airway inoculation of mycoplasma were compared in Ctsl(-/-) and Ctsl(+/+) mice. After infection, Ctsl(-/-) mice demonstrated more body weight loss, greater mortality (22% versus 0%, respectively), and heavier lungs than Ctsl(+/+) mice, but had smaller bronchial lymph nodes. The burden of live mycoplasma in lungs was 247-fold greater in Ctsl(-/-) mice than in Ctsl(+/+) mice after infection for 3 days. Ctsl(-/-) mice exhibited more severe pneumonia and neutrophil-rich, airway-occlusive exudates, which developed more rapidly than in Ctsl(+/+) mice. Compared with the conspicuous remodeling of lymphatics after infection in Ctsl(+/+) mice, little lymphangiogenesis occurred in Ctsl(-/-) mice, but blood vessel remodeling and tissue inflammation were similarly severe. Titers of mycoplasma-reactive IgM, IgA, and IgG in blood in response to live and heat-killed organisms were similar to those in Ctsl(+/+) mice. However, enzyme-linked immunosorbent spot assays revealed profound reductions in the cellular IFN-γ response to mycoplasma antigen. These findings suggest that Ctsl helps contain mycoplasma infection by supporting lymphangiogenesis and cellular immune responses to infection, and our findings predict that the therapeutic inhibition of Ctsl could increase the severity of mycoplasmal infections.

Emergence of atypical Mycoplasma agalactiae strains harboring a new prophage and associated with an alpine wild ungulate mortality episode.

The bacterium Mycoplasma agalactiae is responsible for contagious agalactia (CA) in small domestic ruminants, a syndrome listed by the World Organization for Animal Health and responsible for severe damage to the dairy industry. Recently, we frequently isolated this pathogen from lung lesions of ibexes during a mortality episode in the French Alps. This situation was unusual in terms of host specificity and tissue tropism, raising the question of M. agalactiae emergence in wildlife. To address this issue, the ibex isolates were characterized using a combination of approaches that included antigenic profiles, molecular typing, optical mapping, and whole-genome sequencing. Genome analyses showed the presence of a new, large prophage containing 35 coding sequences (CDS) that was detected in most but not all ibex strains and has a homolog in Mycoplasma conjunctivae, a species causing keratoconjunctivitis in wild ungulates. This and the presence in all strains of large integrated conjugative elements suggested highly dynamic genomes. Nevertheless, M. agalactiae strains circulating in the ibex population were shown to be highly related, most likely originating from a single parental clone that has also spread to another wild ungulate species of the same geographical area, the chamois. These strains clearly differ from strains described in Europe so far, including those found nearby, before CA eradication a few years ago. While M. agalactiae pathogenicity in ibexes remains unclear, our data showed the emergence of atypical strains in Alpine wild ungulates, raising the question of a role for the wild fauna as a potential reservoir of pathogenic mycoplasmas.

Bovine mycoplasmosis: silent and deadly.

The first international conference on bovine mycoplasmosis, held in Saskatoon, Canada, in 2009, marked an official recognition of the importance of mycoplasmas in bovine respiratory disease, mastitis, arthritis and other disorders. Furthermore, bovine mycoplasmosis has been identified as a major emerging infectious disease by the European Community 7th Framework Programme under the EMIDA ERA-NET, which is funding a three-year study into the development of improved diagnosis and control of bovine mycoplasmosis involving the UK, Germany, Italy and Israel. These developments coincide with the publication of the complete sequence of the Mycoplasma bovis genome, which offers fresh insight into the properties of this tiny wall-less bacterium. With this in mind, it is an appropriate time to review our knowledge of cattle diseases caused by mycoplasmas.

Mycoplasma bovis outbreak in a herd of North American bison (Bison bison).

A disease outbreak of high morbidity and high mortality in bison (Bison bison) was investigated. Clinical signs included lameness, swollen joints, respiratory distress, and lethargy. Fifty-three of 194 animals died. Cows between 5 and 10 years of age were the most affected group, in which 40 of 88 animals died. Necropsies were performed on several animals. There were abscesses in the lung and liver, as well as fibrinosuppurative pleuritis, polyarthritis, and disseminated microabscesses in various organs. No significant bacteria were isolated by routine aerobic cultures of lung and liver from 2 representative cases. However, Mycoplasma cultures were positive. Polymerase chain reaction tests on the isolated bacteria were positive for Mycoplasma bovis. Histologically, the abscesses were characterized by areas of necrosis with variable mineralization rimmed by granulomatous inflammation and fibrous tissue. No new animals had been introduced into the herd, but a cattle herd was present adjacent to the affected bison herd. Two restriction fragment length polymorphism techniques were used to compare the bison isolate and another bison isolate from an outbreak in North Dakota with a field isolate of M. bovis from cattle and with a laboratory control strain of M. bovis; the isolates and control strain were found to be similar. The isolates and the control were sequenced and compared with sequences in GenBank. Bison isolates were more than 99% homologous to M. bovis sequences in GenBank. It was concluded that M. bovis in bison can cause disseminated infection with a high morbidity and mortality and that bison isolates are similar to bovine M. bovis isolates.

Anemia in cats with hemotropic mycoplasma infection: retrospective evaluation of 23 cases (1996-2005).

This study summarizes the diagnostic findings from all anemic cats diagnosed with hemotropic mycoplasma (HM) infections at the Western College of Veterinary Medicine-Veterinary Teaching Hospital between 1996 and 2005. The objectives were to determine the frequency of HM-induced anemia among all cats presented with anemia during this period, the clinical findings and risk factors associated with clinical HM infection, and factors affecting or predicting survival. Medical records were examined from 23 cats with HM-induced anemia from the total of 170 cats diagnosed with anemia during this period. The frequency of HM-induced anemia was 14% (23/170) among all anemic cats. Cats with HM-induced anemia were less likely to be purebred (P = 0.04) than other cats with anemia. Of the cats with HM-induced anemia, those with positive retroviral status (P = 0.01), concurrent illness (P < 0.01), or lack of erythroid regeneration (P = 0.01) were most likely to die. The 1-year survival of HM-infected cats was 65% (13/20).

The potential impact of disease on the migratory structure of a partially migratory passerine population.

Since its introduction into eastern North America in the 1940s, the eastern population of house finches (Carpodacus mexicanus) has become partially migratory, unlike its nonmigratory source population in southern California (Able and Belthoff in Proc. R. Soc. Lond. 265 (1410), 2063-2071, 1998; Belthoff and Gauthreaux in Condor 93, 374-382, 1991). The infectious disease mycoplasmal conjunctivitis (pathogen Mycoplasma gallisepticum or "MG"), which has been monitored in the house finch population since its appearance around 1993 (Dhondt et al. in J. Wild. Dis. 34 (2), 265-280, 1998), may induce higher mortality rates among populations in more northerly latitudes relative to more southerly populations. Here, we investigate the potential impact of this differential disease mortality on the migratory structure of the eastern house finch population using an epidemic modeling approach. Analytical and computational results suggest the ongoing MG epidemic in the eastern house finch could lead to increases in the percentage of and the total number of migrating individuals in a population despite overall population declines, assuming relatively high winter mortality rates in the north eastern part of their range. These results also suggest that empirical evidence of such a change in migratory structure would be most noticeable in northerly inland populations that showed significant declines following the initial outbreak of MG in the east.

[Mycoplasma mastitis in dairy cattle]. / Mycoplasma mastitis bij het rund.

The most important characteristics of Mycoplasma mastitis on dairy farms are described, based on two case studies. Clinical symptoms, diagnostics, epidemiology, and a plan of action are presented. In the herds investigated, Mycoplasma mastitis was characterized by multiple affected quarters unresponsive to treatment with antibiotic and/or anti-inflammatory agents. Most striking were a sandy sediment, brown colouring, and rice-like structure of the milk of affected animals. Clinical symptoms differed in the two affected herds. Diagnosis was based on bacteriological investigation of samples of milk and synovial fluid taken from infected cows. Affected animals were culled immediately, and the herds were monitored by repeated testing of bulk milk samples. It was concluded that a consequence of the increasing size of cattle herds in the Netherlands is that subclinical/clinical Mycoplasma mastitis may be diagnosed more frequently than in the past. In the case of Mycoplasma mastitis, farmers and veterinary practitioners are advised to draw up a plan of action together, incorporating aspects such as diagnostics at cow level, direct culling of affected animals, hygiene during milking, including post-milking teat disinfection, and routine monitoring of bulk milk. Unpasteurized milk should not be given to calves.

Contrasting natural experiments confirm competition between House Finches and House Sparrows.

After House Finches were introduced from the western to the eastern United States and rapidly increased in numbers, House Sparrows declined, leading to suggestions that the decline was caused by interspecific competition. However, other potential causes were not excluded. The rapid decline in House Finches following the emergence of a new disease (mycoplasmal conjunctivitis) caused by a novel strain of Mycoplasma gallisepticum (MG) in 1994 has provided a natural experiment and an opportunity to revisit the hypothesis that interspecific competition from House Finches drives population changes in House Sparrows. If true, the recent decline in House Finches should lead to an increase in House Sparrows. In this paper we test the hypothesis that House Sparrow and House Finch numbers in the northeastern United States vary inversely by examining data from three independent volunteer programs that monitor bird species' abundance and distribution (Christmas Bird Count, Project FeederWatch, and Breeding Bird Survey). In the first analysis we found that House Sparrow and House Finch numbers varied inversely during a time interval when House Finches were increasing and a time interval when House Finches were decreasing. In the second analysis, we found that the rates of geometric change in House Sparrow abundance (ln[HOSP(t+1)/HOSP(t)]) were negatively correlated with initial House Finch (HOFI(t)) and sparrow (HOSP(t)) abundances at individual sites, irrespective of the time period. Given that finch range expansion and subsequent declines in abundance are the result of two very different phenomena, it would be very unlikely for apparent competition or spurious correlations to cause the observed concomitant changes in House Sparrow abundance. We conclude that interspecific competition exists between these two species.

Characterization of experimental Mycoplasma gallisepticum infection in captive house finch flocks.

The use of controlled, horizontal-transmission experiments provides detailed information on the spread of disease within fixed social groups, which informs our understanding of disease dynamics both in an empirical and theoretical context. For that reason, we characterized in 2002, horizontal transmission of Mycoplasma gallisepticum (MG) in two flocks of 11 wild-caught house finches housed in outdoor aviaries over a 6-mo period. All birds were initially free of MG by a polymerase chain reaction (PCR)-based test, rapid plate agglutination (RPA), and the scoring of physical signs. We inoculated one flock member bilaterally in the palpebral conjunctiva and reintroduced it into its cage. Index birds developed conjunctivitis within 3 to 5 days but died 13 and 20 days postinfection (PI) possibly because of very severe weather. The proportion of birds with physical signs increased gradually, reached 40% at 6 wk PI, and fluctuated around 40% until 21 wk PI. By the time our experiment ended at 24.5 wk PI, 28% of the birds still exhibited physical signs. Across both flocks, 80% of the birds developed unilateral or bilateral conjunctivitis, and several birds relapsed. The appearance of physical signs in new individuals occurred between 10 and 144 days PI (median 41 days PI). Physical signs lasted 1-172 days (median 42 days). Birds that became infected earlier during the experiment developed more severe conjunctivitis, and there was a tendency for birds that developed bilateral conjunctivitis to develop physical signs earlier. Most birds that developed physical signs of MG were also PCR- and RPA-positive, although we detected a single asymptomatic carrier and a single symptomatic false negative. No birds died as a result of secondary MG infection.

Concurrent infections with vector-borne pathogens associated with fatal hemolytic anemia in a cattle herd in Switzerland.

Bovine anaplasmosis is a vector-borne disease that results in substantial economic losses in other parts of the world but so far not in northern Europe. In August 2002, a fatal disease outbreak was reported in a large dairy herd in the Swiss canton of Grisons. Diseased animals experienced fever, anorexia, agalactia, and depression. Anemia, ectoparasite infestation, and, occasionally, hemoglobinuria were observed. To determine the roles of vector-borne pathogens and to characterize the disease, blood samples were collected from all 286 animals: 50% of the cows were anemic. Upon microscopic examination of red blood cells, Anaplasma marginale inclusion bodies were found in 47% of the cows. The infection was confirmed serologically and by molecular methods. Interestingly, we also found evidence of infections with Anaplasma phagocytophilum, large Babesia and Theileria spp., and Mycoplasma wenyonii. The last two species had not previously been described in Switzerland. Anemia was significantly associated with the presence of the infectious agents detected, with the exception of A. phagocytophilum. Remarkably, concurrent infections with up to five infectious vector-borne agents were detected in 90% of the ill animals tested by PCR. We concluded that A. marginale was the major cause of the hemolytic anemia, while coinfections with other agents exacerbated the disease. This was the first severe disease outbreak associated with concurrent infections with vector-borne pathogens in alpine Switzerland; it was presumably curtailed by culling of the entire herd. It remains to be seen whether similar disease outbreaks will have to be anticipated in northern Europe in the future.

Mycoplasma bovis-associated suppurative otitis media and pneumonia in bull calves.

Outbreaks of Mycoplasma bovis-associated otitis media and pneumonia occurred on four beef cattle farms in Hokkaido, Japan between 2000 and 2001. The morbidity and mortality were estimated at 8-40 and 30-100%, respectively. Eight calves with bilateral ear droop and exudative otitis media were examined bacteriologically and histopathologically. M. bovis was isolated post mortem from nasal swabs and from the ears, lungs, lymph nodes (cranial and pulmonary), brain and heart of all calves. At necropsy, suppurative exudates were observed in the tympanic bullae of all cases. Numerous abscesses were also found in the petrous portion of the temporal bone and lungs in seven cases. Histopathologically, the exudates within the tympanic bullae consisted of a mixture of neutrophils, necrotic cell debris and fibrin, and the tympanic mucosa was thickened with neutrophil and macrophage infiltration and proliferation of fibrous connective tissue. Pulmonary lesions included extensive foci of coagulative necrosis surrounded by numerous neutrophils. Hepatocytes or renal tubular epithelial cells were enlarged with hyaline cytoplasmic inclusions in four calves. Immunohistochemical labelling confirmed the presence of M. bovis antigen in the cytoplasm of the inflammatory cells in the middle ear, temporal bone and lungs, and was also demonstrated within the cytoplasmic inclusions of the hepatocytes and renal tubular epithelial cells. Ultrastructurally, mycoplasma-like organisms, 200-500 microm in diameter, were found within not only hepatocytes and renal tubular epithelia but also within axons of the facial nerves. The present results show that M. bovis spreads to multiple organs and is capable of invading various kinds of host cell. The intracellular localization may be favourable for evading host immune responses.