Community Acquired Infections Division, Centre for Communicable Diseases and Infection Control, Public Health Agency of Canada, 100 Eglantine Driveway, Ottawa, ON K1A 0K9, Canada. email@example.com
Investigations related to tuberculosis (TB) cases on airline flights have received increased attention in recent years. In Canada, reports of air travel by individuals with active TB are sent to the Public Health Agency of Canada (PHAC) for public health risk assessment and contact follow-up. A descriptive analysis was conducted to examine reporting patterns over time.
Reports of air travel by individuals with active TB received by PHAC between January 2006 and December 2008 were reviewed. Descriptive analyses were performed on variables related to reporting patterns, characteristics and actions taken.
The number of reports increased each year with 18, 35 and 51 reports received in 2006, 2007 and 2008, respectively. Of the 104 total cases, most were male (63%) and born outside of Canada (87%). Ninety-eight cases (97%) met the criteria for infectiousness and a contact investigation was initiated for 136 flights.
Reports of air travel by individuals with active TB have been increasing annually in Canada in recent years. Outcomes of the subsequent contact investigations, including passenger follow-up results and evidence of TB transmission, is necessary to further evaluate the effectiveness of the Canadian guidelines.
A long-term observation for 12 years revealed a tendency to stabilization of localization of tuberculous infection foci in rural areas and their main concentration in large villages. In such villages 82.7 per cent of new cases of tuberculosis and 80.3 per cent of new cases of tuberculous infection were recorded. The tension of the epidemiological situation with respect to tuberculosis in rural areas directly depended on the number of tubercle bacilli carriers living in such areas. It was maintained by three factors: migration of the bacilli carriers, the number of new cases of bacillary tuberculosis of the lungs and the results of their therapy. Among persons having family contacts with tubercle bacilli carriers, the incidence of pulmonary tuberculosis was 12.4 and 40.6 times higher than that resulting from professional and village contacts, respectively. A differential approach to organization of anti-epidemiological measures, early detection and prophylaxis of tuberculosis in rural areas is proposed.
To describe the demographic and geographic distribution of tuberculosis (TB) in Manitoba, thus determining risk factors associated with clustering and higher incidence rates in distinct subpopulations.
Data from the Manitoba TB Registry was compiled to generate a database on 855 patients with tuberculosis and their contacts from 1992-1999. Recovered isolates of M. tuberculosis were typed by IS6110 restriction fragment length polymorphisms. Bivariate and multivariate logistic regression models were used to identify risk factors involved in clustering.
A trend to clustering was observed among the Canadian-born treaty Aboriginal subgroup in contrast to the foreign-born. The dominant type, designated fingerprint type 1, accounts for 25.8% of total cases and 75.3% of treaty Aboriginal cases. Among type 1 patients residing in urban areas, 98.9% lived in Winnipeg. In rural areas, 92.8% lived on Aboriginal reserves. Statistical models revealed that significant risk factors for acquiring clustered tuberculosis are gender, age, ethnic origin and residence. Those at increased risk are: males (p
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The paper outlines the results of following up 50 infants and preschool children who had contacts on their families. The major sources of infection were equally both their mother and their father. The children were found to have pronounced active processes. The most severe types of tuberculosis were common in infants in whom general, military tuberculosis and tuberculous meningitis along with complicated types in intrathoracic lymph node tuberculosis were detected. There was more commonly a phase of dissemination and decay in infants. Severe types of tuberculosis were encountered in the families having a combination of many unfavourable factors, both medical and social ones. Among the children who had fallen ill, 32% were detected on their visits to polyclinics of upon admissions to general hospitals.
Programs to prevent the incidence rate of tuberculosis (TB) from increasing in many low-incidence countries are challenged by international travel and immigration from high-burden countries.
The current study aimed to determine the effect of such immigration on the genetic diversity of Mycobacterium tuberculosis isolates in an entire nation's population during 1994-2005.
A total of 3,131 patients were notified with TB during the 12-year period. Of these, 2,284 (73%) had TB verified by culture, and isolates from 2,173 (96%) of these were analyzed by IS6110 restriction fragment length polymorphism.
Only 31% of the included strains were isolated from nonimmigrants, the remaining 69% were isolated from immigrants. Although the incidence increased throughout the period, the genetic diversity remained high. A total of 135 clusters were identified; the percentage of recent disease was reduced among nonimmigrants, and remained stable among the immigrants during the study period. Although 69% of the isolates originated from immigrants from high-incidence countries, the established TB control program in the receiving country was adequate for the prevention of disease transmission. On average per year, only 2 nonimmigrants and 13 immigrants developed disease as a result of infection within the country by imported M. tuberculosis.
Twelve years of M. tuberculosis importation as a result of immigration from high-incidence countries had little influence on the transmission of this pathogen in the receiving low-incidence country. To prevent future increase of transmission of TB, the current control strategies of low-incidence countries are adequate but must be maintained.
Comment In: Am J Respir Crit Care Med. 2007 Nov 1;176(9):840-217951558
The purpose of the study was to assess the incidence and relative risk of hepatitis A and B and tuberculosis among Danish merchant seamen. We also assessed the occurrence of malaria. The study was based on record linkage of a research database containing data on 24,132 Danish male seamen and the Registry for Notifiable Infectious Diseases in Denmark, supplemented by data from other sources. The standardized incidence ratio (SIR) for hepatitis A for male seamen was 1.77 (0.91-3.10) as compared with the incidence in the general population. The incidence was 0.9 notified cases/10,000 years. The SIR for hepatitis B for male seamen was 3.02 (1.79-4.78), the main risk factors being intravenous drug use and casual sex abroad. Tuberculosis was not more common among seamen than in non-seamen. The results have implications for vaccination strategies in this occupational group. Malaria occurred frequently in the seamen, especially among those involved in West African trade. Irregular use of malaria prophylaxis and probably chloroquine resistance were of importance in some cases. To detect further cases of hepatitis A and B and malaria, other sources were reviewed. Only a few extra cases were identified. The registry of notifiable infectious diseases was thus found to be rather complete.