0 2000 4000 6000 8000 10000 12000 14000 16000 18000 19801981198219831984198519861987198819891990199119921993199419951996199719981999200020012002200320042005200620072008200920102011 Nu m ber o f C ases
Totaal Enteritidis Typhimurium Andere
Figure 34. Trend of the human Salmonella isolates and of the two major serotypes Enteritidis and Typhimurium over the last thirty one years in Belgium:
51
Seasonal Distribution 2006-2011
0 100 200 300 400 500 600Jan Feb Ma Apr May Jun Jul Aug Sep Oct Nov Dec
Nu
m
be
r o
f C
ases
2006 2007 2008 2009 2010 2011Figure 35. Trend of the human Salmonella isolates and of the two major serotypes Enteritidis and Typhimurium over the last thirty one years in Belgium: num-
ber of laboratory confirmed cases.
Age and seasonal distribution
Most cases of salmonellosis were reported in children less than 5 years old (37,6% of cases), with no significant gender difference.
Table 22. Human cases of Salmonella: Age and gender distribution 2011. Note that the gender of all salmonellosis cases is not known.
M: male; F: female; SR: sex ratio
Salmonella Salmonella Enteritidis Salmonella Typhimurium
Age Total M F SR Total Total M F SR Total Total M
< 1 year 268 142 122 1,2 22 268 142 122 1,2 22 268 142 1 to 4 1217 596 613 1,0 149 1217 596 613 1,0 149 1217 596 5 to 14 years 746 368 376 1,0 122 746 368 376 1,0 122 746 368 15 to 24 years 185 93 92 1,0 34 185 93 92 1,0 34 185 93 25 to 44 years 230 118 112 1,1 52 230 118 112 1,1 52 230 118 45 to 64 years 257 130 126 1,0 59 257 130 126 1,0 59 257 130 ≥ 65 years 265 136 126 1,1 37 265 136 126 1,1 37 265 136 unknown 63 11 21 0,5 6 63 11 21 0,5 6 63 11 Total 3231 1594 1588 1,0 481 3231 1594 1588 1,0 481 3231 1594
Regarding the seasonal distribution (Fig. 35), about 200 to 300 cases were monthly reported between January and July 2011. From July until September, the monthly number of isolates increased, to reach approximately 400 isolates. From October to December, the monthly number of isolates gradually decreased.
1.8. Tuberculosis
Maryse Fauville-Dufaux, Marc Govaerts, Luc Vanholme, Maryse Wanlin
1.8.1. Zoonotic tuberculosis
(Mycobacterium bovis)
Tuberculosis in humans caused by Mycobacterium bovis is rare. In regions where M. bovis infections in cattle are largely eliminated, only few residual cases occur either among elderly persons as a result of the reactivation of dormant M. bovis within old lesions and among migrants from high-prevalence countries. Agricultural workers may get infected by M. bovis by inhaling aerosols from coughing infected cattle and may subsequently develop typical pulmonary or genito-urinary tuberculosis. Such patients may infect cattle through cough or urine. Evidence for human-to-human transmission of zoonotic tuberculosis is only rarely reported.
In developing countries, where M. bovis is largely prevalent among cattle, some studies reported that 3-6% of all tubercu- losis cases are due to M. bovis and that mostly young people get infected through the ingestion of contaminated raw milk. Also occupational contacts should be regarded as a risk factor for transmission to humans, although companion animals can provide a less common indirect route of infection.
In humans, the disease caused by M. bovis is clinically indis- tinguishable from that caused by M. tuberculosis. Pulmonary tuberculosis is frequently observed and cervical lymphadenop- athy, intestinal lesions, chronic skin tuberculosis and other non pulmonary forms are particularly common.
1.8.2. Mycobacterium bovis in cattle
Belgium is officially free from bovine tuberculosis (Myco- bacterium bovis) since 25 June 2003 (Commission Decision 2003/467/EC establishing the official tuberculosis, brucellosis and enzootic bovine leucosis free status of certain Member States and regions of Member States as regards bovine herds).
1.8.2.1. Surveillance programme
The control of tuberculosis is based on Council Directive 64/432/EEC, which is implemented and adapted in the national legislation since 1963 and was last amended by Royal Decree of 17 October 2002.
The control implies:
• Skin testing of animals at purchase (mandatory),
• In case of a positive reactor, skin testing of all the animals of
the holding and skin testing of all contact animals (tracing on and tracing back),
• Systematic post mortem examinations at the slaughter-
house. In case a suspected lesion is identified, a sample is sent to the NRL for analysis.
The FASFC is informed about any doubtful or positive result of the skin test and may decide to re-examine (additional tests) the animals or to kill them (test slaughter, additional tests). If M. bovis is isolated as a consequence of post mortem examina- tions or of mandatory test-slaughter, all animals in the herd of origin are skin tested and a complete epidemiological investi- gation is performed.
An animal is defined as infected with bovine tuberculosis if the skin testing is positive or if M. bovis is isolated by culture or confirmed by laboratory testing (PCR). A holding is defined as infected if M. bovis was isolated or detected by PCR from an animal of the holding.
Isolation of M. bovis and biochemical testing is exclusively performed in the NRL where also IFN-gamma and molecular typing by means of IS6110 RFLP, spoligotyping and MIRU-VNTR are done.
In Belgium, vaccination against tuberculosis is prohibited.
1.8.2.2. Epidemiological investigations and results of 2010- 2011 surveillance
At the slaughterhouse, tissue samples from individual animals were taken. The samples originated from animals suspected of being infected with M. bovis, i.e. skin test reactors, animals that had been in contact with M. bovis infected animals or animals that showed suspicious lesions at meat inspection. The samples were submitted to the NRL where culture, PCR and confirmatory tests were done. M. bovis was only detected in animals belonging to the outbreak herds.
The evolution of tuberculosis outbreaks in Belgian cattle herds over the last years is indicated in table 23 and figure 36.
53
Table 23. Evolution of bovine tuberculosis outbreaks in cattle herds in
Belgium, period 2000-2011 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 TB Break- downs 24 23 13 7 8 5 8 5 12 2 0 1
The NRL performs routine IS6110 RFLP typing and spoligotyp- ing of M. bovis field isolates. Since 1995, the strains of 96% of the outbreak herds are typed by both methods. More recently, all strains typed by RFLP and spoligotyping were addition- ally analysed by MIRU-VNTR, which is done in collaboration with IPH. As a consequence, a comprehensive database of the vast majority of M. bovis types isolated in Belgium since 1995 is maintained. Analysis of molecular profiles of all isolates obtained from Belgian TB breakdowns until 2009 allowed the identification of a predominant spoligotype (SB0162). Only one bovine TB breakdown was found over this 2-years reporting period. Clustering of this isolate within the 1995-2010 collection based on its molecular profile is yet undetermined.
1.8.3. Mycobacterium bovis in wildlife
During the period 2000 – 2011, all suspected lesions of wildlife were send to the NRL for analysis of tuberculosis. This pas- sive monitoring never caused a positive result for M. bovis by culture. Only environmental Mycobacteria could be detected in wildlife.
In 2011, in consequence of the tuberculosis outbreak detection in one bovine herd, 230 wildboars and 23 badgers originating from the surrounding areas of the outbreak herd were analysed for M. bovis. All results were negative.
24 23 13 7 8 5 8 5 12 2 0 1 0 5 10 15 20 25 30 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
TB Breakdowns
Figure 36. Evolution of bovine tuberculosis breakdowns in cattle herds in
Belgium, period 2000 – 2011
1.8.4. Mycobacterium bovis in humans
Mycobacterium bovis can infect humans and cause a disease similar to infections with M.tuberculosis. The main transmission routes of M.bovis to humans are contaminated food (especially raw milk or milk products) or direct contact with animals. In 2010, 15 human cases of bovine tuberculosis were identified and confirmed by culture followed by molecular identification in the NRL, Scientific Institute of Public Health. For 2 of these patients a specimen was obtained at the end of 2009 but was identified only in 2010. Eight patients were from Belgian origin. Among the 15 patients, 6 pulmonary forms of the disease, 1 pleural tuberculosis, 1 cervical lymphadenopathy, 1 tonsillitis, and several abdominal diseases were observed. One Belgian patient, plumber in a hospital, was infected by a multidrug resistant M. bovis and developed a pulmonary zoonosis which was the result of a nosocomial contamination. He never had di- rect contact with the index patient but had to repair piping in the toilet next to her room during her hospitalization in 2008. The isolates from both patients had the same spoligotype and MIRU-VNTR patterns. Genotyping made it possible to prove that the worker had an occupational disease. The index case was a woman from foreign origin already detected in 2005 with abdominal tuberculosis. As the patient was not compliant to the treatment, the M. bovis strain evolved to multidrug resist- ance in 2007 and was also isolated from respiratory specimens in 2008.
On the other hand, genotyping allowed identification of 2 clusters, both including 2 Belgian patients infected by the same strain (88 and 100 years old; 50 and 62 years old).
In 2011, 12 human cases of bovine tuberculosis were identified and confirmed by culture followed by molecular identification in the NRL. Among the 12 patients, 4 pulmonary forms of the disease, 1 pleural tuberculosis, 3 cervical lymphadenopathy were observed. All the bovis strains were genotyped by the spoligotyping technique.
Zoonosis due to M .bovis is not frequent in Belgium and was more often detected in patients from North Africa. Notewor- thy, the number of cases in the old Belgian population slightly increased over the last years and could be a reactivation of a previous disease. This justifies a special attention to the identification of the species M. bovis within the Mycobacte- rium tuberculosis complex, which is not possible with the most common molecular techniques used in the laboratories to identify positive cultures of mycobacteria. M. bovis being re- sistant to pyrazinamid, this first-line drug must not be included in the treatment of zoonosis.
1.8.5. Human tuberculosis
(Mycobacterium tuberculosis)
The incidence of human tuberculosis shows little variation over the last years. From 2001 to 2011 respectively 1321, 1309, 1128, 1226, 1144, 1127, 1028, 1006, 1020, 1115 and 1085 (provisional) new notified cases of active human tuberculosis were detected. In 2010, over the 66,1% were male patients and 49% of the tuber- culosis cases were foreigners. In 2011, 65,8% were male patients and 54,6% of the tuberculosis cases were foreigners.
Groups at risk are persons with a marginal existence, asylum seekers and refugees. Alcoholism and a co-infection with HIV are known as specific risk factors. Human tuberculosis cases are mainly concentrated in urban populations.
1321 1309 1128 1226 1144 1127 1028 1006 1020 1115 1085 0 200 400 600 800 1000 1200 1400 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011