Brucella suis biovar 2 infection in humans in France: emerging infection or better recognition?

Brucellosis is usually acquired by humans through contact with infected animals or the consumption of raw milk from infected ruminants. Brucella suis biovar 2 (BSB2) is mainly encountered in hares and wild boars (Sus scrofa), and is known to have very low pathogenicity to humans with only two case reports published in the literature. Human cases of brucellosis caused by BSB2 were identified through the national mandatory notification of brucellosis. The identification of the bacterium species and biovar were confirmed by the national reference laboratory. Epidemiological data were obtained during medical follow-up visits. Seven human cases were identified between 2004 and 2016, all confirmed by the isolation of BSB2 in clinical specimens. All patients had direct contact with wild boars while hunting or preparing wild boar meat for consumption. Five patients had chronic medical conditions possibly responsible for an increased risk of infection. Our findings suggest that BSB2 might be an emerging pathogen in hunters with massive exposure through the dressing of wild boar carcasses. Hunters, especially those with chronic medical conditions, should be informed about the risk of BSB2 infection and should receive information on protective measures.

Urgent request on avian influenza.

Highly pathogenic avian influenza (HPAI) H5N8 is currently causing an epizootic in Europe, infecting many poultry holdings as well as captive and wild bird species in more than 10 countries. Given the clear clinical manifestation, passive surveillance is considered the most effective means of detecting infected wild and domestic birds. Testing samples from new species and non-previously reported areas is key to determine the geographic spread of HPAIV H5N8 2016 in wild birds. Testing limited numbers of dead wild birds in previously reported areas is useful when it is relevant to know whether the virus is still present in the area or not, e.g. before restrictive measures in poultry are to be lifted. To prevent introduction of HPAIV from wild birds into poultry, strict biosecurity implemented and maintained by the poultry farmers is the most important measure. Providing holding-specific biosecurity guidance is strongly recommended as it is expected to have a high impact on the achieved biosecurity level of the holding. This is preferably done during peace time to increase preparedness for future outbreaks. The location and size of control and in particular monitoring areas for poultry associated with positive wild bird findings are best based on knowledge of the wider habitat and flight distance of the affected wild bird species. It is recommended to increase awareness among poultry farmers in these established areas in order to enhance passive surveillance and to implement enhanced biosecurity measures including poultry confinement. There is no scientific evidence suggesting a different effectiveness of the protection measures on the introduction into poultry holdings and subsequent spread of HPAIV when applied to H5N8, H5N1 or other notifiable HPAI viruses.

Human brucellosis in France in the 21st century: Results from national surveillance 2004-2013.

Brucellosis is a bacterial zoonotic disease mainly transmitted to humans by ruminants. In France, brucellosis has disappeared from ruminants herds. Human brucellosis surveillance is performed through mandatory notification and the national reference center. METHODS: We report the results of human brucellosis surveillance from 2004 to 2013 with regards to epidemiological, clinical and microbiological data. RESULTS: A total of 250 cases were notified, making an annual incidence of 0.3 cases per million inhabitants. Brucella melitensis biovar 3 was the most frequently identified bacterium (79% of isolated strains). In total, 213 (85%) cases had been contaminated abroad in endemic countries. In 2012, an episode of re-emergence of brucellosis in cattle occurred in Haute-Savoie, in the French Alps, and was responsible for 2 human cases. CONCLUSION: Brucellosis has become a disease of travelers in France. However, maintaining a stringent epidemiological surveillance is necessary to be able to early detect any local re-emergence in humans or animals. The multidisciplinary surveillance was implemented in France years ago and is a successful example of the One Health Concept.

Evaluation of three competitive ELISAs and a fluorescence polarisation assay for the diagnosis of bovine brucellosis.

Bovine brucellosis is an infectious disease of worldwide public health and economic importance. The usual tests for the diagnosis of this disease include the Rose-Bengal test (RBT), complement fixation test (CFT), serum agglutination test (SAT) and indirect ELISA. New tests such as competitive ELISAs (C-ELISA) and fluorescence polarisation assay (FPA) have been developed. However, C-ELISA may correspond to different protocols and a wide variation may exist in their diagnostic performance. The aim of this study was to evaluate three commercially available C-ELISA kits (C-ELISA1-3) and FPA for the diagnosis of bovine brucellosis and compare test performance with RBT, CFT, indirect ELISA and FPA. Sera submitted to EU laboratories in 2011 from 5111 adult cattle were tested. Individual test sensitivities (Se) and specificities (Sp) were estimated. Threshold assessment using the receiver operating characteristic method was also performed. The most sensitive tests were FPA (99.0%; 95% confidence interval [CI], 97.9-100%), C-ELISA1 (98.4%; 95% CI, 97.0-99.8%) and RBT (97.7%; 95% CI, 95.9-99.3%). The most specific tests were CFT (99.98%; 95% CI, 99.93-100%), SAT (99.98%; 95% CI, 99.93-100%) and RBT (99.89%; 95% CI, 99.79-99.99%). Among the new tests, none of the three C-ELISA kits studied could be recommended as a single screening test because of their low specificity, especially when used in a herd. C-ELISA3 could not be recommended as confirmatory test on individual animals to determine whether false positive serological test results had occurred.

Assessment of the sensitivity of the gamma-interferon test and the single intradermal comparative cervical test for the diagnosis of bovine tuberculosis under field conditions.

In some French départements, the eradication of bovine tuberculosis is incomplete and usual skin tests [single intradermal tuberculin test (SIT) and single intradermal comparative cervical test (SICCT)] have poor specificity due to cross-reactions with non-pathogenic mycobacteria, causing economic losses. In Côte d'Or (Burgundy, France), an experimental serial testing scheme based on the combination of SICCT and gamma-interferon (IFN-γ) tests has been initiated in order to shorten the interval between suspicion and its invalidation in herds with false-positive results to skin tests. Our aim was to assess the scheme's sensitivity and to compare it to the sensitivity of the screening scheme recommended by the European Commission. Our study included 1768 animals from Côte d'Or. The sensitivities of both schemes were estimated using a Bayesian approach. The individual sensitivity of the IFN-γ test [88·1%, 95% credibility interval (CrI) 72·8-97·5] was not significantly different from individual SICCT sensitivity (80·3%, 95% CrI 61·6-98·0) and individual SIT sensitivity (84·2%, 95% CrI 59·0-98·2). The individual specificity of the IFN-γ test was 62·3% (95% CrI 60·2-64·5). No significant difference could be demonstrated between the sensitivities of the serial testing scheme used in Côte d'Or (73·1%, 95% CrI 41·1-100) and the European Union serial testing scheme (70·1%, 95% CrI 31·5-100·0).

Brucellosis in terrestrial wildlife.

The epidemiological link between brucellosis in wildlife and brucellosis in livestock and people is widely recognised. When studying brucellosis in wildlife, three questions arise: (i) Is this the result of a spillover from livestock or a sustainable infection in one or more host species of wildlife? (ii) Does wildlife brucellosis represent a reservoir of Brucella strains for livestock? (iii) Is it of zoonotic concern? Despite their different host preferences, B. abortus and B. suis have been isolated from a variety of wildlife species, whereas B. melitensis is rarely reported in wildlife. The pathogenesis of Brucella spp. in wildlife reservoirs is not yet fully defined. The prevalence of brucellosis in some wildlife species is very low and thus the behaviour of individual animals, and interactions between wildlife and livestock, may be the most important drivers for transmission. Since signs of the disease are non-pathognomonic, definitive diagnosis depends on laboratory testing, including indirect tests that can be applied to blood or milk, as well as direct tests (classical bacteriology and methods based on the polymerase chain reaction [PCR]). However, serological tests cannot determine which Brucella species has induced anti-Brucella antibodies in the host. Only the isolation of Brucella spp. (or specific DNA detection by PCR) allows a definitive diagnosis, using classical or molecular techniques to identify and type specific strains. There is as yet no brucellosis vaccine that demonstrates satisfactory safety and efficacy in wildlife. Therefore, controlling brucellosis in wildlife should be based on good management practices. At present, transmission of Brucella spp. from wildlife to humans seems to be linked to the butchering of meat and dressing of infected wild or feral pig carcasses in thedeveloped world, and infected African buffalo in the developing world. In the Arctic, the traditional consumption of raw bone marrow and the internal organs of freshly killed caribou or reindeer is an important risk factor.

Modelling transmission of bovine tuberculosis in red deer and wild boar in Normandy, France.

In early 2001, Mycobacterium bovis infection was confirmed in red deer (RD) (Cervus elaphus) shot in Normandy region, France. An epidemiological survey conducted during the following hunting season in two connected forests confirmed the occurrence of the disease in both free-ranging RD and wild boar (WB) (Sus scrofa). This was the first detected bovine tuberculosis outbreak in wildlife in France. We present a simple deterministic age-structured model of the within- and between-species M. bovis transmission in RD and WB populations that distinguishes direct transmission (horizontal and pseudo-vertical) and indirect transmission through contaminated offal left behind by hunters. Results issued from the epidemiological surveys conducted in Normandy forests were used to estimate transmission parameters. Because data for RD and WB populations were not available, population sizes at demographic equilibrium were estimated and used to run the model. We qualitatively tested different control measure scenarios with our model, considering different mortality rates and offal harvesting, to determine which ones affect the success of infection control. The most realistic control scenario would combine the total depopulation of RD and good compliance with offal harvesting, because the model suggests that infected offal left by hunters represents the main transmission source of M. bovis in the field.

Re-emergence of brucellosis in cattle in France and risk for human health.

A case of human brucellosis was diagnosed in France in January 2012. The investigation demonstrated that the case had been contaminated by raw milk cheese from a neighbouring dairy farm. As France has been officially free of bovine brucellosis since 2005, veterinary investigations are being conducted to determine the origin of the infection and avoid its spread among other herds. Hypotheses about the source of this infection are discussed.

The first International Standard anti-Brucella melitensis Serum.

The World Organisation for Animal Health (OIE) requested an International Standard anti-Brucella melitensis Serum (ISaBmS) to standardise diagnostic tests and reagents for sheep and goats. The agreed criteria were the highest dilution (in negative serum) of the standard which must give a positive result and the lowest dilution (in negative serum) which must simultaneously give a negative result. The two dilutions for each assay were, respectively: indirect enzyme-linked immunosorbent assay (iELISA) 1/64 and 1/750, competitive ELISA (cELISA) 1/8 and 1/300, fluorescent polarisation assay (FPA) 1/16 and 1/200, Rose Bengal test (RBT) 1/16 and 1/200. The OIE International Standard Serum (OIEISS) will remain the primary standard for the RBT; the ISaBmS is an additional standard. It was impossible to set criteria for the complement fixation test, therefore the OIEISS will remain the primary standard. The ISaBmS can be used to standardise iELISA, cELISA and FPA to diagnose sheep and goat brucellosis. This standard should facilitate harmonisation of tests used for brucellosis surveillance and international trade in these species.

[Unexpected increase of human and animal tularemia cases during winter 2007/2008 in France: Emergence or short-lasting episode?]. / Excès de cas humains et animaux de tularémie en France au cours de l'hiver 2007-2008 : émergence ou phénomène isolé ?

CONTEXT: Tularemia is a zoonosis affecting humans and hares in France. We describe the results of surveillance in both species, in 2007 and 2008. METHODS: Human tularemia cases are mandatorily notifiable in France since 2003. In hares, surveillance relies on volunteer hunter associations in all districts of the country. Data from mandatory reports and volunteer surveillance in 2007/2008 were analyzed and compared with previous results. RESULTS: In 2007/2008, 144 cases were reported in humans and 117 cases in hares. This was a 100% increase compared to previous years. Human cases differed from those of previous years only by the frequency of contact with breeding animals. Human cases without any documented risk exposure were also more frequent. CONCLUSION: An increase of tularemia cases occurred in 2007/2008 in both species. Complementary studies are needed to identify the species reservoir in France to understand the causes of this peak of cases.

[Brucella bacteremia reactivation 70 years after the primary infection]. / Réactivation bactériémique d'une brucellose 70ans après la primo-infection.

After primary infection, some bacteria can remain in a latent state for several years before a new bacteremia, often due to a weakened immune status. This is common for Mycobacterium tuberculosis, less for other pathogens more difficult to have in mind when facing patients with fever. We report the case of an 84-year-old female patient presenting with fever in the months following antilymphoma chemotherapy, due to bacteremic brucellosis (with a hemophagocytic syndrome) probably latent after primary infection as a child.

Eradication of bovine brucellosis in the Azores, Portugal-Outcome of a 5-year programme (2002-2007) based on test-and-slaughter and RB51 vaccination.

Bovine brucellosis is an important contagious disease that can cause abortions and infertility in cattle, and can be transmitted to humans. Despite having an eradication programme in place since 1994, in 2000 the situation of bovine brucellosis due to Brucella abortus was not significantly improving in 3 of the 9 islands (Terceira, S. Miguel and S. Jorge) of the archipelago of Azores, an autonomous region of Portugal. Farming on these islands, particularly dairy, is extensive. Therefore, the use of RB51 vaccine, which does not induce antibodies detectable with routine brucellosis diagnostic tests, was implemented. This article reports the results of an eradication programme based on RB51 mass vaccination combined with test-and-slaughter, which was implemented in the Azores during the 2002-2007 period. During the first round of vaccination, both adult cows and heifers were vaccinated. Subsequently, only replacement stock aged 4-12 months, were immunized with RB51.The test-and-slaughter policy based on bulk milk ring test (MRT) and serological surveillance was maintained. During this period, the average brucellosis herd incidence, herd prevalence and individual prevalence decreased 69.26%, 39.26% and 75.41% respectively for the three above-mentioned islands. However, disease reduction approaching eradication was obtained only on the island of Terceira, where a high level of vaccine coverage was rapidly reached and regularly maintained together with strict application of a test-and-slaughter programme. This work shows that the RB51 vaccine could be a useful tool for eradicating bovine brucellosis in well-controlled epidemiological units provided that there is mass vaccine coverage for a sufficiently long period of time and it is combined with an appropriate test-and-slaughter programme.

Brucella suis infection in domestic pigs and wild boar in Croatia.

Between the years 2000 and 2004, 93,107 sera from 1,997 pig herds in 11 regions of Croatia were tested for the presence of antibodies against brucellosis. Positive results were observed in 67 herds from seven regions (mean individual prevalence: approximately 1%; herd prevalence: 3.4%). The herds from all but two of the infected farms were reared outdoors and thus almost certainly came into contact with wildlife. From 2003 to 2004, 424 sera, which were randomly collected from hunted wild boar (Sus scrofa), were also tested and shown to have a mean seroprevalence of 27.6%. Brucella was isolated from 88 out of 151 serologically positive pigs (58.3%) and 7 of the 93 (7.5%) wild boar which were randomly submitted for bacteriological study. All but three isolates were Brucella suis biovar 2; the others being biovar 3. These results suggest that brucellosis is enzootic in Croatian populations of wild boar. These populations represent a potential disease reservoir for free-range pig farms, as they do in other countries of Central and Western Europe. This is the first report of B. suis biovar 3 in swine and wild boar in Europe, which is an issue of serious concern for public health.

Evaluation of a multiplex PCR assay (Bruce-ladder) for molecular typing of all Brucella species, including the vaccine strains.

An evaluation of a multiplex PCR assay (Bruce-ladder) was performed in seven laboratories using 625 Brucella strains from different animal and geographical origins. This robust test can differentiate in a single step all of the classical Brucella species, including those found in marine mammals and the S19, RB51, and Rev.1 vaccine strains.

Reference laboratory networking: the European experience in brucellosis.

Over the past forty years, a huge effort of standardisation of tests and harmonisation of sanitary policies and requirements has been made in the European Union (EU). The EU has itself greatly evolved in its size and policies. Voluntary uncoordinated actions initially had some success but not enough to attain a level of standardisation compatible with a single market and to achieve the sanitary level foreseen by the community. The creation of a Community Reference laboratory with specific responsibilities and tasks and the provision of adequate financial assistance is expected to lead to better co-ordination of activities and to ensure international harmonisation of tests and procedures.

Prevalence of classical swine fever, Aujeszky's disease and brucellosis in a population of wild boar in Switzerland.

During two survey rounds of a national surveillance system for infectious diseases in wild boar in Switzerland, each lasting four months from November to February, between 2001 and 2003, 1949 blood samples and 62 tissue samples from the spleen and 50 from the reproductive organs were collected from hunted wild boar. The survey was designed so that freedom from infection could be detected with a probability of 95 per cent at a threshold prevalence of less than 1 per cent for classical swine fever and Aujeszky's disease and less than 1.5 per cent for brucellosis. There was no serological evidence of classical swine fever or Aujeszky's disease, but brucellosis due to Brucella suis biovar 2 was confirmed serologically and by bacterial isolation.