Tuberculosis due to Mycobacterium bovis in the Australian population: cases recorded during 1970-1994.

OBJECTIVE: To determine the contribution of Mycobacterium bovis to active tuberculosis in the Australian population during 1970-1994, and to collate and analyse demographic data from bacteriologically proven cases. DESIGN: Summary data for tuberculosis cases notified by Australian public health agencies during 1970-1985 and 1991-1994 were obtained from the database of notifiable diseases maintained by the Department of Health and Family Services. More detailed demographic data for cases confirmed by bacteriology during 1970-1994 were supplied by the Australian Mycobacterium Reference Laboratory Network. RESULTS: At least 236 cases of bovine tuberculosis (TB) occurred in the Australian population during 1970-1994 (mean 9.4 cases; range 3-22 cases annually). The bovine strain has accounted for around 1% of Australian cases of TB during this period. Laboratory sources provided demographic data for 150 cases with positive bacteriology. For this group, the mean age was 54 years (range 22-86), and the male:female ratio was 2.4:1. The majority of cases (74%) involved pulmonary disease. Australian-born persons accounted for 68% of the total cases and typically had histories of employment in meat and/or livestock industries. CONCLUSION: M. bovis was responsible for less than 1.5% of cases of TB in the Australian population during 1970-1994. Most cases were apparently due to reactivation of infection acquired through occupational exposure. Thus, although virtual eradication of M. bovis from Australia's cattle herds has now reduced the risk of exposure, it can be expected that human cases of bovine TB will continue to be detected for years to come. The bovine strain should be considered as the possible agent of TB in foreign-born Australians.     

Epidemiology of Mycobacterium bovis disease in San Diego County, 1994-2000.

SETTING: Local public health department. OBJECTIVE: To examine the current epidemiology of Mycobacterium bovis disease in San Diego County and to compare patient characteristics to those of patients with M. tuberculosis disease. DESIGN: Retrospective review of surveillance and epidemiologic data. RESULTS: Between 1994 and 2000, 1,931 evaluable cases of culture-positive TB were identified; 129 were infected with M. bovis and 1,802 were infected with M. tuberculosis. More than 90% of M. bovis cases occurred in Hispanic persons. About 25% of patients were children, and the main site of disease was extra-pulmonary in 53% of patients. Twenty-three per cent had concurrent HIV infection. Compared to patients with M. tuberculosis, patients with M. bovis were more likely to be Hispanic, aged 0-14 years, have extra-pulmonary disease, or have HIV co-infection in a multivariate model. They were less likely to be born in countries outside of the US or Mexico. CONCLUSION: While human disease due to M. bovis has essentially been eliminated in many parts of the US and other industrialized countries, it persists in certain demographic groups, including Hispanic children and HIV-infected adults, in San Diego County.     

Antimicrobial resistance of Mycobacterium tuberculosis isolates from children in Greece, 1994-2004.

OBJECTIVE: To document the prevalence of resistance to various agents of Mycobacterium tuberculosis strains derived from children over 1994-2004. DESIGN: We prospectively studied the susceptibility patterns of 77 strains of M. tuberculosis isolated from the same number of children, which provided 112 positive samples. RESULTS: Most children were boys (53.2%), native Greeks (87%) and aged under 2 years (41.5%). Sample origin was mainly gastric fluid (97 cases, 86.6%). Sixty-one isolates (79.2%) were susceptible to all anti-tuberculosis agents and 16 (20.8%) were resistant to > or =1 drug. Multidrug resistance (MDR), resistance to at least isoniazid (INH) and rifampicin (RMP), was seen in three cases (3.9%). On comparing resistance to INH, RMP and streptomycin (SM) and MDR in children and adults diagnosed with tuberculosis in our centre during the same time period, SM resistance was significantly more common in children (P < 0.001), while a trend for increased resistance to INH was also observed in children (P = 0.079). CONCLUSION: Resistance of M. tuberculosis isolates to the first line anti-tuberculosis drugs appears to be comparable in children and adults in Greece, while SM resistance appears to be more common in children. Tracing the sources of these children is important for the effective surveillance and treatment of tuberculosis.     

Human tuberculosis due to Mycobacterium bovis: report of 10 cases.

During the period 1986-1990, 10 cases of human disease caused by Mycobacterium bovis were diagnosed in our hospital. The incidence, in relation to the cases of disease from Mycobacterium tuberculosis diagnosed in the same period, was 0.9%. The patients had an average age of 32 years (range 5-68 years). Pulmonary disease was observed in 5 patients (50%), lymphadenitis in 2, pleural effusion in 2 and peritoneal in 1. The most significant of the epidemiological features was that 2 patients were veterinary students. There was 1 death from ovarian neoplasia with abdominal dissemination. The other cases responded favourably to treatment with standard chemotherapy of 6-12 months achieving cure, without relapse, of all the patients.     

Pulmonary tuberculosis due to Mycobacterium bovis in León.

In recent years, human infection due to Mycobacterium bovis has been considered almost eradicated in most industrialised countries. During the period 1998-2002, nine patients were diagnosed with pulmonary tuberculosis (TB) due to M. bovis in the Hospital Monte San Isidro, León, Spain. Their average age was 66 years. The response to therapy was good in seven cases, while two died, one from renal TB and the other from cancer of the pancreatic head.     

Treatment of Mycobacterium bovis infected tuberculosis patients: San Diego County, California, United States, 1994-2003.

SETTING: A local tuberculosis control program. OBJECTIVE: To examine treatment completion rates of patients with Mycobacterium bovis disease and compare them with those of patients with M. tuberculosis disease. DESIGN: Retrospective review of data from a tuberculosis surveillance computer database. RESULTS: Data from 167 M. bovis patients and 928 M. tuberculosis patients were examined. Rates of treatment completion were not significantly different (78% vs. 82%, chi2 = 1.60, P = 0.174), although death was more frequent among M. bovis patients (15% vs. 7%). The median time to treatment completion was 94 days longer for M. bovis patients. CONCLUSION: Overall, treatment completion rates of M. bovis and M. tuberculosis patients were comparable, although the death rate was higher for M. bovis patients. The latter finding may be related to a particularly high death rate among HIV-infected M. bovis patients. Therapy duration was longer for M. bovis patients, probably because resistance to pyrazinamide prevented the use of a short-course (6-month) regimen.     

Acute, lethal miliary tuberculosis due to Mycobacterium bovis]

The authors report a case of lethal acute miliary with bovine tuberculous bacilli. They stress the main characteristics of this exceptional observation :--difficulties in isolating and identifying,--favourable disposition linked to age and to a depressed cellular immunity,--pathogenic interest in the mechanisms of late endogenous reinfestation and of suffocating acute evolution.     

Tuberculosis in a prison population in Mwanza, Tanzania (1994-1997).

SETTING: Bugando Medical Centre, a referral consultant hospital in the lake zone to which all inmates from Butimba prison are admitted and treated. OBJECTIVE: To determine the extent of open (smear-positive) tuberculosis and other types of tuberculosis among prisoners with tuberculosis. DESIGN: A retrospective cohort study. Case notes of 501 prisoners from January 1994 to December 1997 were retrieved and reviewed. RESULTS: The proportion of open tuberculosis in this study was high, with 204 prisoners (40.7%) having smear-positive tuberculosis. Co-infection was recorded in the majority of patients; HIV/AIDS was recorded in 25.9% of cases. The mean length of imprisonment at the time of diagnosis was 19 months. CONCLUSION: The proportion of open, smear-positive tuberculosis among prisoners admitted with tuberculosis is high. Intervention measures specifically targeting this population are urgently needed in order to contain tuberculosis disease in the prison population.     

Rhinoceros' rhinorrhea: cause of an outbreak of infection due to airborne Mycobacterium bovis in zookeepers.

Seven of 24 zookeepers exposed to a Southern white rhinoceros infected with Mycobacterium bovis were presumably infected via aerosols generated in the cleaning of the barn for the rhinoceros. All demonstrated conversion by the intermediate-strength purified-protein-derivative skin test, but none had clinical illness. In certain occupational settings like zoos and abattoirs, exposure to M. bovis may be an occupational hazard, and routine periodic tuberculin screening should be performed.     

DNA fingerprinting of a national sample of Mycobacterium tuberculosis isolates, Botswana, 1995-1996.

DNA fingerprinting may be useful to elucidate tuberculosis (TB) transmission in community settings, but its utility is limited if only few fingerprint patterns are observed or band numbers are low. We performed DNA fingerprinting on a national, population-based sample of Mycobacterium tuberculosis isolates from Botswana. During 1995-1996, a random sample of 213 isolates, representing 5% of all smear-positive TB cases, underwent DNA fingerprinting using restriction fragment length polymorphism (RFLP) IS6110 analysis. Eighty-two (38%) of the 213 isolates belonged to one of 18 clusters, with 2-9 isolates/cluster. The median number of bands was 10 (range 1-19); 183 (86%) had six or more bands. Sixty-three (49%) of 128 patients tested were infected with the human immunodeficiency virus (HIV). The degree of RFLP pattern heterogeneity and high band number support the feasibility of a prospective DNA fingerprinting study in Botswana.     

Tuberculosis trends in Madrid, 1994-2003: impact of immigration and HIV infection.

SETTING: Tuberculosis (TB) cases reported from nine districts of Madrid, where the percentage of immigrant population varied from 1.9% in 1996 to 12.2% in 2003. OBJECTIVE: To describe the trends in TB incidence from 1994 to 2003. DESIGN: Observational study. RESULTS: Between 1994-1995 and 2002-2003, the TB rate decreased from 48.5 (95% CI 45.8-51.1) to 23.3 per 100000 population (95% CI 21.5-25.1) (P < 0.001). The percentage of TB cases co-infected with HIV decreased from 55.9% in 1994 to 14.3% in 2003 (P < 0.001), whereas TB cases in foreigners increased from 2.6% in 1994 to 33.7% in 2003 (P < 0.001). CONCLUSION: Although the TB rates showed a marked decrease in the study period, the increasing impact of immigration contributed to slowing down the trend.     

The population structure of Mycobacterium bovis in Great Britain: clonal expansion

We have analyzed 11,500 isolates of Mycobacterium bovis (the cause of tuberculosis in cattle and other mammals) isolated in Great Britain (England, Wales and Scotland)] and characterized by spoligotype. Genetic exchange between cells is rare or absent in strains of the Mycobacterium tuberculosis complex so that, by using spoligotypes, it is possible to recognize "clones" with a recent common ancestor. The distribution of variable numbers of tandem repeats types in the most common clone in the data set is incompatible with random mutation and drift. The most plausible explanation is a series of "clonal expansions," and this interpretation is supported by the geographical distribution of different genotypes. We suggest that the clonal expansion of a genotype is caused either by the spread of a favorable mutation, together with all other genes present in the ancestral cell in which the mutation occurred, or by the invasion of a novel geographical region by a limited number of genotypes. A similar pattern is observed in M. tuberculosis (the main cause of tuberculosis in humans). The significance of clonal expansion in other bacteria that have recombination is discussed.     

Varicella mortality: trends before vaccine licensure in the United States, 1970-1994

We examined varicella deaths in the United States during the 25 years before vaccine licensure and identified 2262 people who died with varicella as the underlying cause of death. From 1970 to 1994, varicella mortality declined, followed by an increase. Mortality rates were highest among children; however, adult varicella deaths more than doubled in number, proportion, and rate per million population. Despite declining fatality rates, in 1990-1994, adults had a risk 25 times greater and infants had a risk 4 times greater of dying from varicella than did children 1-4 years old, and most people who died of varicella were previously healthy. Varicella deaths are now preventable by vaccine. Investigation and reporting of all varicella deaths in the United States is needed to accurately document deaths due to varicella, to improve prevention efforts, and to evaluate the vaccine's impact on mortality.     

Tuberculosis in ruminants: characteristics of intra-tonsilar Mycobacterium bovis infection models in cattle and deer

Mycobacterium bovis infection produces tubercular lymphadenitis in the head lymphatics of cattle and deer, in addition to pulmonary disease. A low-dose intra-tonsilar infection model that establishes tuberculosis (Tb) lymphadenitis in cattle and deer is characterised in this study. Intra-tonsilar infection of red deer (500 cfus of M. bovis) was monitored longitudinally at 6-week intervals over a period of 23 weeks. Lesion characteristics, bacteriological and immunological parameters were assessed, and compared against those observed in cattle at 20 weeks post-infection, where the latter were infected with 500 or 5000 cfus of M. bovis. Intra-tonsilar inoculation of M. bovis established infection in >90% of deer and cattle, with lesion frequencies at the draining sentinel lymphatic site (left medial retropharyngeal node) of 68-86% and tissue bacterial burdens >3.5 logs/g of tissue, the tonsil being a major site of M. bovis persistence in deer only. Mineralisation occurred at lesion sites in both species in the later stages (18-23 weeks) of infection, with extensive coarse mineralisation observed mainly in cattle. The severity of infection or disease in cattle that received the higher or lower dose of M. bovis did not differ markedly. Pathogen-induced cellular immune response (lymphocyte transformation) and humoral responses (IgG and IgG(1) anti-mycobacterial antibodies) were recorded in both species, and the magnitude of these was noticeably amplified by skin tuberculin testing. IgG(1) antibodies were detectable within 6 weeks post-inoculation in deer and could be associated with early detection of lymphadenitis. Deer and cattle show similar levels of susceptibility to M. bovis infection.     

Use of DNA restriction fragment typing in the differentiation of Mycobacterium tuberculosis complex isolates from animals and humans in Burundi

Setting: Bubanza Hospital and Veterinary Laboratory in Bujumbura, Burundi.Objective: To monitor the rate of Mycobacterium bovis infections among tuberculosis (TB) patients and among slaughtered cattle, and to analyse the polymorphism among deoxyribonucleic acid (DNA) fingerprints of the M. tuberculosis complex isolates.Design: 135 lymph node biopsies and 35 sputum specimens from human patients, together with specimens from 46 healthy animals and 36 animals suspected for bovine tuberculosis (BTB), were cultured. Isolates were identified phenotypically and DNA fingerprints were obtained by IS6110 based restriction fragment length polymorphism.Results: 119 M. tuberculosis complex isolates were obtained from 170 human specimens. M. bovis was not identified in any human sample. One out of 46 healthy animals and 14 out of 36 BTB suspected animals yielded M. bovis isolates. DNA fingerprinting revealed four to eight copies of IS6110 for all M. bovis isolates with some degree of polymorphism, and some clustering for human TB isolates. No relationship was observed between human and bovine isolates.Conclusion: At present M. bovis seems to play a minor role in human TB in Burundi, despite the high prevalence of both human immunodeficiency virus infection in humans and M. bovis in cattle. DNA fingerprinting is able to differentiate between bovine isolates.     

Risk factors for nosocomial transmission of multidrug-resistant tuberculosis due to Mycobacterium bovis among HIV-infected patients.

OBJECTIVE: To identify risk factors for transmission of multidrug-resistant tuberculosis (MDR-TB) among hospitalized human immunodeficiency virus (HIV) infected patients exposed during a nosocomial outbreak. DESIGN: Case control study. Cases were HIV-infected patients with MDR-TB due to Mycobacterium bovis (MDR-TBMb) who acquired the disease after exposure to an MDR-TBMb patient in an hospital ward. Controls were HIV-infected patients exposed to a case of MDR-TBMb in an hospital ward but who did not develop MDR-TBMb during the follow-up. RESULTS: Nineteen cases and 31 controls were included. CD4 cell counts were significantly lower among cases. Exposure in the infectious diseases ward or exposure to the index patient were associated with development of MDR-TBMb, while exposure during a single-room hospital stay and exposure in the respiratory isolation ward were associated with non-development of MDR-TBMb. A multiple regression logistic model showed that only a CD4 cell count below 50/microL and exposure to the index patient increased the risk of developing MDR-TBMb (P < 0.05). Hospitalization in a single room seemed to protect HIV-infected patients from developing nosocomial MDR-TBMb (P = 0.052). CONCLUSIONS: Over classic risk factors, such as length of exposure or sharing a room with a case, severe immunosuppression independently increases the risk of MDR-TB transmission in the context of a nosocomial MDR-TB outbreak among HIV-infected patients. This information must be considered in the management of tuberculosis outbreaks. Patients with CD4 cell counts below 50/microL should be the principal group targeted for prevention strategies in nosocomial outbreaks.     

Genetic and serovar typing of clinical isolates of the Mycobacterium avium-intracellulare complex

Setting: One hundred and thirty-four Mycobacterium avium-intracellulare complex (MAC) isolates were obtained from 121 patients in the UK.Objective: To compare serotyping and genetic analysis for species identification of MAC isolates from patients with and without the acquired immunodeficiency syndrome (AIDS).Design: Clinical MAC isolates were cultured and analyzed by serotyping, the commercially available Accuprobe kit, hybridization with genes coding for the 19 kDa and 38 kDa antigens of M. tuberculosis and fingerprinting with the pMB22 probe derived from M. paratuberculosis.Results: Species classification on the basis of genetic analysis was similar to serovar typing, with only exceptional discrepancies. Serovar prevalence was different in the two groups of patients, and different from those reported in other countries. MAC isolates from AIDS patients were exclusively M. avium, whereas patients without AIDS had MAC infections with M. avium and M. intracellulare in about equal proportion. M. intracellulare clinical isolates were genetically more heterogeneous than M. avium. Only M. intracellulare hybridized with the 38 kDa gene probe.Conclusions: Serovars are strongly linked with species in clinical MAC isolates, confirming results previously obtained with reference strains. M. intracellulare can be easily identified by the presence of a 38 kDa gene.