Factors associated with severity of bovine tuberculosis in Ethiopian cattle.

Bovine TB is a disease of high economic and public health importance particularly in resource poor countries. Many aspects of pathogenesis of bovine TB in cattle have not been well understood. We carried out an investigation on 337 Ethiopian cattle with characteristic TB-like lesions to describe severity of pathology and factors associated with it. Severity of pathology was determined based upon gross lesion characteristics, distribution and presence/absence of viable mycobacteria. Molecular speciation of mycobacteria was performed using Gene-Probe's Accu-Probe method. Mycobacterium bovis was identified by genomic deletion analysis and spoligotyping. Data were analysed using descriptive statistics and regression model. The results showed that TB-like lesions and M. bovis were more frequently observed in lungs and respiratory lymph nodes. Mammary lesions yielded significant proportion of M. bovis upon culturing. Intestinal lesions were the second most frequently encountered pathology; upon culturing, however, the tissue specimens yielded the lowest proportion of M. bovis isolates. Sex, breed and management system were found to significantly affect TB manifestation. Female (ß ± SE = 4.1 ± 1.0; P = 0.00) and exotic breed (ß ± SE = 1.7 ± 0.9; P = 0.045) were at a relatively higher risk of developing severe tuberculosis. TB pathology was more severe in cattle raised under large-scale farming (ß ± SE = 2.3 ± 0.5; P = 0.00). The fact that severe tuberculosis is linked to high degree of disease transmission potential warrants implementation of proper disease surveillance programs in large-scale farms. Isolation of M. bovis from mammary and muscle tissues implies a potential threat of zoonotic transmission, where raw milk and raw beef constitute a customary dietary regimen in Ethiopia.

Risk factors associated with prevalence of tuberculosis-like lesions and associated mycobacteria in cattle slaughtered at public and export abattoirs in Ethiopia.

This study was aimed at investigating risk factors associated with prevalence of tuberculosis (TB)-like lesions and associated mycobacteria in Ethiopian cattle slaughtered. The study was carried out during 2006-2007 in five selected municipal and export abattoirs. Methods of investigation involved detailed necropsy examination of carcasses and isolation of mycobacteria from pathologic tissue specimens. Factors of animal and environment origin were recorded and examined as explanatory variables in relation to the presence or absence of TB-like lesions and the presence of viable mycobacteria. Multivariable logistic regression analysis was used to identify risk factors associated with prevalence of TB-like lesions and mycobacteria. Out of 3,322 carcasses inspected, 10.2% (95% confidence interval (CI) [9.2-11.3]) and 3.2% (95% CI [2.6-3.8]) were positive, respectively, based on necropsy and bacteriologic examinations. The highest and lowest lesion prevalence was recorded in Adama (24.7%) and Yabello (4.2%), respectively. Multivariable logistic regression analysis identified age, breed, abattoir location, geographic origin and management system as being risk factors for prevalence of TB-like lesions and occurrence of viable mycobacteria in Ethiopian cattle. The study demonstrated mycobacterial infection as important infectious disease of Ethiopian cattle. The reported confirmed cases of the disease in different management and geographic settings in Ethiopia disproved the earlier held opinion of its occurrence as a low sporadic profile. In view of a dietary proclivity of Ethiopian communities (milk and meat are predominantly consumed raw) and lifestyle (close contact of people with animals), the risk of bovine tuberculosis as a public health threat is eminent.

Molecular characterization of Mycobacterium bovis isolates from Ethiopian cattle.

BACKGROUND: Bovine Tuberculosis (BTB) is a widespread and endemic disease of cattle in Ethiopia. Information relating to genotypic characteristics of Mycobacterium bovis strains affecting the cattle population in Ethiopia is limited. We carried out molecular characterization of M. bovis strains isolated from BTB infected cattle using the spoligotyping technique. The relationship between distribution of spoligotypes and recorded variables was also investigated. A new approach that can numerically reflect the degree of genetic polymorphism in a M. bovis population was also developed. The study was conducted from July 2006 to January 2007 in cattle slaughtered at five representative abattoirs in Ethiopia. RESULTS: Forty-five M. bovis isolates were obtained from 406 pathologic tissue specimens collected from 337 carcasses with lesions compatible with BTB. Twelve spoligotypes were identified from 34 distinct strains; with SB1176 as a dominant spoligotype (41.2% of the isolates) followed by SB0133 (14.7%). Comparison of spoligotypes with an M. bovis global database http://www.mbovis.org revealed six new spoligotypes which were subsequently registered in the database with international identification codes of SB1517, SB1518, SB1519, SB1520, SB1521 and SB1522. The majority of strains were obtained from cattle slaughtered at Addis Ababa abattoir. On the basis of the Spoligotype Evolutionary Index, SEI (a numeric expression approach to make standardized comparison of spoligotype evolution), M. bovis isolates from Ethiopia were relatively more heterogeneous (SEI = 3.2) compared to isolates from other countries. This might be attributed to extensive livestock movement linked to trading or seasonal migration, high degree of livestock mingling, and also diversities of the country's agricultural and livestock ecosystems, in addition to lack of disease control measures that led to high infection prevalence. Multiple spoligotype infection was recorded in nine (50%) of infected carcasses and this may indicate the prevailing high degree of super infection. CONCLUSIONS: This study provided molecular evidence for the widespread distribution of M. bovis in the cattle population in Ethiopia. It also demonstrated a relatively high degree of genetic polymorphism of the isolates. Further molecular investigation of M. bovis strains in humans and other domestic animals is recommended in order to elucidate the zoonotic importance as well as reservoirs and pattern of transmission among various hosts.

Diagnostic efficiency of abattoir meat inspection service in Ethiopia to detect carcasses infected with Mycobacterium bovis: implications for public health.

BACKGROUND: Bovine Tuberculosis (BTB) is a widespread and endemic disease of cattle in Ethiopia posing a significant threat to public health. Regular surveillance by skin test, bacteriology and molecular methods is not feasible due to lack of resource. Thus, routine abattoir (RA) inspection will continue to play a key role for national surveillance. We evaluated efficiency of RA inspection for diagnosis of Mycobacterium bovis infection and discussed its public health implications in light of a high risk of human exposure. METHODS: The study was conducted in five abattoirs: Addis Ababa, Adama, Hawassa, Yabello and Melge-Wondo abattoirs. The efficiency of routine abattoir (RA) inspection was validated in comparison to detailed abattoir (DA) inspection, followed by culture and microscopy (CM) and region of difference (RD) deletion analysis. Diagnostic accuracies (with corresponding measures of statistical uncertainty) were determined by computing test property statistics (sensitivity and specificity) and likelihood estimations using web-based SISA diagnostic statistics software. Post-test probability of detecting TB infected carcasses was estimated using nomograms. Agreement between RA and DA inspections was measured using kappa statistics. The study was conducted and reported in accordance with standards for reporting of diagnostic accuracy (STARD) requirements. Both routine and detailed meat inspection protocols were performed on a subpopulation of 3322 cattle selected randomly from among 78,269 cattle slaughtered during the study period. Three hundred thirty seven carcasses identified through detailed meat inspection protocols were subjected to culture and microscopy; of the 337, a subset of 105 specimens for culture and microscopy were subjected to further molecular testing. RESULTS: There was a substantial agreement between RA and DA inspections in Addis Ababa (Kappa = 0.7) and Melge-Wondo abattoirs (Kappa = 0.67). In Adama, Hawassa and Yabello abattoirs, the agreement was however poor (Kappa

Applying the epidemiologic problem oriented approach (EPOA) methodology in developing a knowledge base for the modeling of HIV/AIDS.

INTRODUCTION: In the epidemiologic modeling of diseases, the epidemiologic problem oriented approach (EPOA) methodology facilitates the development of systematic and structured knowledge bases, which are crucial for development of models. A detailed understanding of the epidemiology of a given disease provides the essential framework for model development and enables the laying out of the comprehensive and fundamental structures for the models. OBJECTIVE: To develop such a knowledge base for developing HIV/AIDS models. METHODS: The EPOA methodology was utilized to develop the knowledge base for HIV/AIDS; it is composed of six pillars within two triads: the Problem Identification/Characterization and the Problem Management/Solution/Mitigation Triads, interlinked by the diagnostic procedure. RESULTS: Using information from various sources, the triads are decomposed into their respective pillar variables and parameters. The agent pillar identifies the causative agent (HIV) and its characteristics. The host pillar identifies and characterizes the host (human). The environment pillar characterizes the physical, biological and socioeconomic environments for both the host and agent. The therapeutics/treatment pillar considers the treatment options for HIV/AIDS. The prevention/control pillar considers prevention and control measures. The health maintenance/health promotion pillar considers measures for the health maintenance of the population. CONCLUSION: Models for HIV/AIDS can be conceptual, in vivo or in vitro, systems analysis, mathematical, or computational just to name a few. The knowledge base developed using the EPOA methodology provides a well-organized structured source of information, which is used in the variable and parameter estimations as well as analysis (biological, mathematical, statistical and computer simulations), which are crucial in epidemiologic modeling of HIV/AIDS. EPOA methodology has become an important tool in the development of models that can enlighten decision making in public health.

Assessing HIV/AIDS intervention strategies using an integrative macro-micro level computational epidemiologic modeling approach.

INTRODUCTION: Epidemiologic research involves the study of a complex set of host, environmental and causative agent factors as they interact to impact health and diseases in any population. The most advanced of these efforts have focused on micro (cellular) or macro (human) population level studies but lacked the integrative framework as presented in this article. Modeling the cumulative impact of HIV/AIDS at the cellular, molecular, and individual behaviors at the population-level can be complex. The main objective of our research is to develop a macro-micro level computational epidemiologic model that integrates the dynamic interplay of HIV/AIDS at the cellular and molecular level (micro-epidemiologic modeling), and the dynamic interplay of multifactorial determinants: biomedical, behavioral, and socioeconomic factors at the human population level (macro-epidemiologic modeling). METHODS: The computational epidemiologic model was constructed using systems dynamics modeling methodology. The dynamics of the relationships was described by means of ordinary/partial differential equations. All state equations in the model were approximated using the Runge-Kutta 4th order numerical approximation method. RESULTS: Computational tools and mathematical approaches that integrate models from micro to macro levels in a seamless fashion have been developed to study the population-level effects of various intervention strategies on HIV/AIDS. The critical variables that facilitate transmission of HIV and intracellular interactions and molecular kinetics were examined to assess different interventions strategies. Such multilevel models are essential if we are to develop quantitative, predictive models of complex biological systems such as HIV/AIDS.

Assessing the Key Attributes of Low Utilization of Mammography Screening and Breast-self Exam among African-American Women.

PURPOSE: African-American (AA) women living in four Black Belt Counties (BBC) of Alabama; consisting of Barbour, Macon, Green and Wilcox are known to have lower mammogram utilization and breast self-exam rates when compared to their white female counterparts. The influence of socioeconomic and demographic factors on these disparities has not been clearly defined so far. Our study was designed to determine whether these observed disparities can be predicted with the socioeconomic and other demographic attributes. METHODS: Health Disparity Questionnaires data (n = 516) for BBC of Alabama was analyzed using a logistic regression model to examine the association of breast cancer screening rates and breast self-exam with income, the level of education, family doctor, type of health insurance, obesity, and age. RESULTS: Income, education, family doctor, age and health insurance were independent predictors for the low utilization rate of mammography and breast self-exam (BSE). CONCLUSION: Improving socioeconomic conditions such as level of education and availability of health care are essential to increase the rates of breast cancer screening test and breast self-exam in the BBC of Alabama.

The Role of Computational Epidemiology and Risk Analysis in the Fight Against HIV/AIDS.

Substantial progress in the understanding of HIV and CD4 cell dynamics using computational models undergirded by sound epidemiologic and mathematical principles has been achieved. The early stages of the applications of these models were based on relatively simple mathematical models that considered the body as a one-compartment system. In spite of these models attractiveness due to the experimental and/or mathematical standpoints, the underlying simplification neglected a lot of important factors affecting the population dynamics both on macro (human) and micro (cellular) population levels. This simplification also affected the kinetics linked to the immunology, infection and chemotherapy dynamics throughout the host. Epidemiologic research involves the study of a complex set of host, environmental and causative agent factors as they interact to impact health and diseases in any given population whether biotic or abiotic. This leads in generating large data sets which require the use of powerful computational methods for studying these large and complex models by means of computational epidemiologic methods. Another dimension of a great challenging problem to public health decision makers is that of emerging diseases, as they have to face and deal with a lot of uncertainty at the early stages of disease outbreaks. However, at this juncture, epidemiologic problem-solving and decision-making often proceeds in the face of uncertainties and limited information. One methodology to address these types of shortcomings is the application of risk analysis. Risk analysis is a process for decision making under uncertainty that consists of three fundamental tasks: risk management, risk assessment, and risk communication. Excitingly, the prospective role that computational models and risk analysis may possibly play in the advancement of the theoretical understanding of disease processes and the identification of specific intervention strategies holds the potential to impact and save human lives.

The Association between Interrelationships and Linkages of Knowledge about HIV/AIDS and its Related Risky Behaviors in People Living with HIV/AIDS.

The relationship between knowledge about HIV/AIDS and its associated risky behaviors is complex and has not been sufficiently explored. It is especially important to look at some of the aspects of this relationship among people living with HIV/AIDS (PLWHA) in order to develop effective intervention strategies to reduce HIV/AIDS risky behaviors. The objective of this study was to investigate the association between knowledge about HIV/AIDS and its risky behaviors among PLWHA. METHODS: Risk taking behavior among the participants was measured as the number of all risky behaviors before and after the knowledge of their HIV/AIDS positive status. Knowledge was measured by the extent to which participants answered the HIV/AIDS related questions. The relationships between the identified HIV/AIDS risky behaviors and the knowledge among PLWHA were analyzed using Structural Equation Modelling. RESULTS: 341 questionnaires were administered and 326 (96%) were completed and returned from PLWHA clients of HIV/AIDS outreach facility in Alabama. Analysis revealed that, knowledge of HIV/AIDS, and knowledge of a properly used condom in preventing the infection through sexual activity were positively related with knowledge of where to get tested for HIV/AIDS. Using drugs before sex was significantly related with having sex with prostitutes (total effects' standardized regression coefficient (TESRC)=0.29, p<0.001). Sharing the same syringe or needle with another person or other people to inject oneself was strongly related with number of sexual partners within one year (TESRC=0.25, p<0.001), and sex with injecting drug users (TESRC=0.45, p<0.001). CONCLUSION: A deeper understanding of HIV/AIDS and some of its transmission pathways appears to be very effective in practicing the taking of preventive measures such as using condoms or getting tested for HIV. Increasing access to HIV/AIDS education could therefore be very useful in providing further gains in HIV/AIDS awareness among PLWHA.