[show abstract][hide abstract] ABSTRACT: Data on genotypic diversity of Mycobacterium tuberculosis complex (MTBC) is important to understand its epidemiology, human adaptation, clinical phenotypes, and drug resistance. This study aimed to characterize MTBC clinical isolates circulating in a predominantly pastoralist area in Ethiopia, a country where tuberculosis is the second leading cause of mortality. Culture of sputum samples collected from a total of 325 pulmonary TB suspects was done to isolate MTBC. Spoligotyping was used to characterize 105 isolates from culture positive slopes and the result was compared with an international database. Forty-four spoligotype patterns were observed to correspond to 35 shared-types (SITs) containing 96 isolates and 9 orphan patterns; 27 SITs containing 83 isolates matched a preexisting shared-type in the database, whereas 8 SITs (n=13 isolates) were newly created. A total of 19 SITs containing 80 isolates were clustered within this study (overall clustering of 76.19%). Three dominant lineages (T, CAS, and Manu) accounted for 76.19% of the isolates. SIT149/T3-ETH was one of the two most dominant sublineages. Unlike previous reports, we show that Manu lineage strains not only constitute a dominant lineage, but are also associated with HIV infection in Afar region of Ethiopia. The high level of clustering suggests the presence of recent transmission that should be further studied using additional genotyping markers.
BioMed Research International 03/2014; 2014(ID 238532):12 pages. · 2.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: Little attention has been given to the role of antibodies against Mycobacterium tuberculosis (Mtb) infection. We have compared the levels of IgA and IgG against ESAT-6/CFP-10 and Rv2031c antigens in sera of culture-confirmed pulmonary tuberculosis (PTB) patients, healthy Mtb infected and non-infected individuals in endemic TB settings. Venous blood samples were collected from 166 study participants, sera were separated and assayed by an enzyme-linked immunosorbent assay (ELISA). QuantiFERON-TB Gold In-Tube (QFTGIT) assay was used for the screening of latent TB infection. The mean optical density (OD) values of IgA against ESAT-6/CFP-10 and Rv2031 were significantly higher in sera of patients with culture confirmed PTB compared to healthy Mtb-infected and non-infected individuals (p<0.001). The mean optical density (OD) values of IgG against ESAT-6/CFP-10 and Rv2031 were also significantly higher in sera of patients with culture confirmed PTB compared to healthy Mtb-infected and non-infected individuals (p<0.05). The mean OD values of IgA against both antigens were also higher in sera of healthy Mtb-infected cases compared to non-infected individuals. There were positive correlations (p<0.05) between the level of IFN-γ induced in QFTGIT assay and the OD values of serum IgA against both antigens in healthy Mtb-infected subjects. The current study shows the potential of IgA response against ESAT-6/CFP-10 and Rv2031 antigens in discriminating clinical TB from healthy Mtb-infected and non-infected cases. Nevertheless, further well designed cohort study is needed to fully realize the full potential of this diagnostic marker. This article is protected by copyright. All rights reserved.
Scandinavian Journal of Immunology 05/2013; · 2.20 Impact Factor
[show abstract][hide abstract] ABSTRACT: Bovine tuberculosis (BTB) has a potential public health risk and economic impact in pastoralist community whose livelihood depends on their livestock. A cross-sectional study was carried out from September, 2008 to June, 2011 on 1087 cattle under pastoral and agro-pastoral production system in four districts of Afar Pastoral Region of Ethiopia using comparative intradermal tuberculin skin test to estimate the prevalence of BTB and assess the associated risk factors for infection. The individual animal prevalence of BTB in cattle of Afar pastoralists was 11% (95% confidence interval (CI): 9 to 13%) with ≥ 4 mm cut-off and 18% (95% CI: 16% to 21%) with ≥2 mm cut-off. The herd prevalence was 44% (95% CI: 36 to 51%) and 56% (95% CI: 48 to 63%) at ≥4 and ≥2 mm cut-off points, respectively. In bivariate analysis, the prevalence was significantly associated with study districts, herd size, sex and age, and in multivariable logistic regression analysis, the statistical significance was maintained with study district, age and herd size of the cattle. In conclusion, the present study revealed a moderately high prevalence of BTB in Afar Pastoral Region of Ethiopia and further investigation is recommended to assess the zoonotic significance of the disease to the pastoralist communities of the region.
Journal of Veterinary Medicine and Animal Health. 05/2013; 5(6):171-179.
[show abstract][hide abstract] ABSTRACT: Background: Information on the community-based prevalence of tuberculosis (TB) in different
settings is vital for planning, execution and evaluation of strategies to control the disease.
Objective: To assess community-based prevalence of undetected active pulmonary TB (PTB) in
pastoralists of the Amibara District.
Methods: BetweenMarch and April 2010, a community-based cross-sectional survey of undiagnosed
active PTB was conducted in the pastoralists of the Amibara District of the Afar Region,
north-east Ethiopia. The study participants were interviewed for symptoms suggestive of PTB
using a structured questionnaire. Sputum samples were collected and processed for smear
microscopy and culture. Mycobacterium genus typing was performed using a multiplex polymerase
chain reaction (PCR).
Results: Out of 222 individuals who had symptoms suggestive of PTB, 4 (1.8%) were found positive
by smear microscopy, while mycobacterial growth was observed on 62 (27.9%) samples.
Mycobacterium genus typing was carried out for 42 of these 62 samples; 39 (92.9%) gave a positive
signal for the genus Mycobacterium. Of these, 23 (59%) isolates proved to bemembers of the
Mycobacterium tuberculosis (Mtb) complex, while the remaining 16 (41.0%) were found to be
members of non-tuberculous Mycobacteria (NTM) species.
Conclusion: Sputumculture is highly sensitive, and it is the gold standard for the bacteriological
diagnosis of PTB, while smear microscopy is less sensitive to detect acid fast bacilli (AFB) in
stained sputum smears. The findings of the present study warrant the strengthening of culture
facility services in the study area. The study also provides important preliminary information on
the status of NTM infection in the pastoral setting. Nevertheless, further investigations into the
species identification of the NTM infections would be useful in the study area.
International Journal of Mycobcateriology. 04/2013; xxx(xxx):xxx.
[show abstract][hide abstract] ABSTRACT: Bacille Calmette-Guérin (BCG), developed a century ago, is the only licensed tuberculosis (TB) vaccine in use to date. The protective efficacy of BCG against TB varies with no apparent protection in some population, and mechanisms of its immune protection is poorly known, and yet BCG is the most widely used vaccine, with more than 4 billion BCG-vaccinated children globally. BCG is probably the only licensed vaccine currently in use believed to mediate immune protection through the production of interferon (IFN)-γ by CD4 T cells, which in turn activates macrophages to kill Mycobacterium tuberculosis (Mtb). Currently, a number of new TB candidate vaccines are in different phases of clinical trial. The majority of these new vaccines are either recombinant forms of BCG or prime boosters of BCG (rBCG) and their immunogenicity is tested using BCG as a benchmark by measuring specific IFN-γ produced by CD4(+) T cells as a protective immune marker. However, some recent studies that examined mechanisms of immune protection of BCG in animals and humans have reported a lack of correlation between IFN-γ production by CD4 cells and BCG-induced immune protection. These studies point to the fact that there is a missing link in our understanding of TB immunology. Conversely, there is emerging evidence that other T cell subsets (gammadelta, γδ), CD8(+) T cells and natural killer (NK) cells may play a vital role in immune protection against Mtb infection and BCG-induced immune protection. γδ T cells and NK cells, which were considered to be part of the innate immunity in the past, have been shown to develop immunological memory upon re-encounter with the same pathogen. In this paper, the controversy over the role of IFN-γ as a marker for protective immunity against TB, and emerging data on the role of γδ T cells, CD8(+) and NK cells in TB immunology, will be presented.
[show abstract][hide abstract] ABSTRACT: A cross sectional study was conducted on 2231 small ruminants in four districts of the Afar Pastoral Region of Ethiopia to investigate the epidemiology of tuberculosis in goats and sheep using comparative intradermal tuberculin skin test, postmortem examination, mycobacteriological culture and molecular typing methods. The overall animal prevalence of TB in small ruminants was 0.5% (95% CI: 0.2%–0.7%) at ≥4 mm and 3.8% (95% CI: 3%–4.7%) at cutoff ≥2 mm. The herd prevalence was 20% (95% CI: 12–28%) and 47% (95% CI: 37–56%) at ≥4 mm and ≥2 mm cut-off points, respectively. The overall animal prevalence of Mycobacterium avium complex infection was 2.8% (95% CI: 2.1–3.5%) and 6.8% (95% CI: 5.8–7.9%) at ≥4 mm and ≥2 mm cut-off points, respectively. Mycobacteriological culture and molecular characterization of isolates from tissue lesions of tuberculin reactor goats resulted in isolation of Mycobacterium tuberculosis (SIT149) and non-tuberculosis mycobacteria as causative agents of tuberculosis and tuberculosis-like diseases in goats, respectively. The isolation of Mycobacterium tuberculosis in goat suggests a potential transmission of the causative agent from human and warrants further investigation in the role of small ruminants in epidemiology of human tuberculosis in the region.
Veterinary Medicine International. 07/2012; 8(2012 Article ID 869146):8.
[show abstract][hide abstract] ABSTRACT: TB is a major public health problem globally and Ethiopia is 8th among the 22 high burden countries. Early detection and effective treatment are pre-requisites for a successful TB control programme. In this regard, early health seeking action from patients' side and prompt diagnosis as well as initiation of treatment from the health system's side are essential steps. The aim of this study was to assess delay in the diagnosis and treatment of TB in a predominantly pastoralist area in Ethiopia.
On a cross-sectional study, two hundred sixteen TB patients who visited DOTS clinics of two health facilities in Afar Region were included consecutively. Time from onset of symptoms till first consultation of formal health providers (patients' delay) and time from first consultation till initiation of treatment (health system's delay) were analyzed.
The median patients' and health system's delay were 20 and 33.5 days, respectively. The median total delay was 70.5 days with a median treatment delay of 1 day. On multivariate logistic regression, self-treatment (aOR. 3.99, CI 1.50-10.59) and first visit to non-formal health providers (aOR. 6.18, CI 1.84-20.76) were observed to be independent predictors of patients' delay. On the other hand, having extra-pulmonary TB (aOR. 2.08, CI 1.08- 4.04), and a first visit to health posts/clinics (aOR. 19.70, CI 6.18-62.79), health centres (aOR. 4.83, CI 2.23-10.43) and private health facilities (aOR. 2.49, CI 1.07-5.84) were found to be independent predictors of health system's delay.
There is a long delay in the diagnosis and initiation of treatment and this was mainly attributable to the health system. Health system strengthening towards improved diagnosis of TB could reduce the long health system's delay in the management of TB in the study area.
BMC Public Health 05/2012; 12:369. · 2.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: There is growing evidence showing the potential of T-cell-based gamma interferon (IFN-γ) release assays (IGRAs) for predicting the risk of progression of Mycobacterium tuberculosis (Mtb) infection, though there is little information from tuberculosis (TB)-endemic settings. In this study, we assessed the association between the level of IFN-γ produced by T cells in response to Mtb-specific antigens and the size of skin test indurations in 505 adult individuals who were screened for latent tuberculosis infection (LTBI) using the QuantiFERON-TB Gold In Tube (QFTGIT) assay and tuberculin skin test (TST). There was a strong positive correlation between the level of IFN-γ induced by the specific antigens and the diameter of the skin indurations (Spearman's rho = 0.6, P < 0.001). Body mass index and parasitic infection were not associated with the level of IFN-γ production or the TST reaction. In linear regression analysis, the size of the skin test indurations was significantly associated with the mean level of IFN-γ [coefficient, 0.65; 95% confidence interval (CI), 0.47 to 0.82, P < 0.001]. Similarly, results from logistic regression analysis demonstrated that individuals who had skin test indurations ≥ 10 mm were 6.82 times more likely than individuals who had skin test indurations < 10 mm to have high levels of IFN-γ (i.e. positive QFTGIT result) (adjusted odd ratio = 6.82; 95% CI, 3.67 to 12.69, P < 0.001). In conclusion, the results of this study could provide indirect evidence for the prognostic use of the QFTGIT assay for progression of Mtb infection, though prospective follow-up studies are needed to provide direct evidence.
International Immunology 02/2012; 24(2):71-8. · 3.14 Impact Factor
[show abstract][hide abstract] ABSTRACT: To determine the prevalence of pulmonary tuberculosis (PTB) and associated risk factors among inmates in three major prison settings of Eastern Ethiopia.
Between July and November, 2008, 371 prisoners with a history of cough of ≥ 2 weeks were screened for PTB using direct smear microscopy and culture. Data were analysed using descriptive statistics and multivariable logistic regression.
Of 371 PTB suspects identified by active screening, 33 (8.9%) were confirmed as smear- or culture-positive PTB. Together with the 11 PTB patients already on treatment, the point prevalence of PTB was 1913 per 100,000 (95%CI 1410-2580), about seven times higher than that of the general population. Eleven newly diagnosed PTB patients were sharing a cell with known TB patients. Factors significantly associated with PTB were young age (15-44 years of age) (OR 3.73), urban residence (OR 3.59), having a cough >4 weeks (OR 3.15), and sharing a cell with a TB patient (OR 3.39) or a prisoner with chronic cough (OR 4.5).
The study documented a high prevalence of PTB among Ethiopian prisoners. Socio-demographic and TB management factors were identified to be underlying causes of the high transmission rate and the acquisition of new cases. Active surveillance of TB and implementing prevention and control guidelines are imperative.
The international journal of tuberculosis and lung disease: the official journal of the International Union against Tuberculosis and Lung Disease 05/2011; 15(5):668-73. · 2.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: Infection with Mycobacterium bovis (Mb) predominantly causes cervical TB lymphadenitis (TBL). Raw milk is considered the main source of Mb infection and raw milk is a major food source for Afar pastoralists. The aim of this study was to assess Afar pastoralists' knowledge concerning cervical TBL and its treatment.
A community-based cross-sectional survey involving 818 interviewees was conducted in two districts of the Afar Region, Ethiopia. In addition, two focus group discussions (FGDs) were conducted in each of the study areas, one with men and the other with women.
Of the 818 interviewees [357 (43.6%) females and 461 (56.4%) males], 742 (90.7%) reported that they had knowledge of cervical TBL, mentioning that swelling(s) on the neck resulting in a lesion and scar are common symptoms. However, only 11 (1.5%) individuals mentioned that bacteria or germs are the causative agents of TBL. Three interviewees and a male discussant mentioned drinking raw milk as the cause of TBL. A considerable proportion (34.2%) of the interviewees and almost all the discussants suggested herbal medicine as an effective treatment. Male study participants were 1.82 times more likely to have overall knowledge of TBL than female study participants (adjusted OR, 1.82; 95% CI, 1.32 to 2.51, p < 0.001).
The pastoral community members in the study areas had little biomedical knowledge of the cause, the source of infection and the transmission route of cervical TBL. Furthermore, most community members believed that herbal medicines are the most effective treatment for TBL. Therefore, TB control programs in the Afar Region require the incorporation of public health education introducing current biomedical knowledge of the disease. In addition, further studies are important to elucidate which medicinal plants are used by Afar pastoralists to treat TBL.
BMC Public Health 03/2011; 11:157. · 2.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: To assess the level of knowledge and practice related to TB and identify predictive factors in three prisons in eastern Ethiopia: Dire Dawa, Jijiga and Harar.
Between July and November 2008, 382 TB patients and suspects were interviewed using a structured questionnaire. Data were analysed using descriptive statistics and ordinal logistic regression.
Only six (1.6%) prisoners described the cause of TB as being bacterial, while a wind locally known as 'nefas' was frequently mentioned (36.1%); nearly 75% of the prisoners correctly described breath as a mode of TB transmission; 116 (30.7%) did not know any measures for TB prevention and control; and half of the participants did not know that anti-tuberculosis drugs were provided free of charge. Significant predictors of TB knowledge were: incarceration in the Jijiga (OR 9.62, P < 0.001) and Dire Dawa (OR 2.14, P = 0.016) prisons, those who did not consult and receive treatment for TB symptoms (OR 2.46, P < 0.001), and prisoners without a past history of TB (OR 2.72, P = 0.002).
The study demonstrates that prisoners have a modest level of biomedical knowledge. As part of the National TB Programme, health education programmes need to be implemented to enhance prisoners' knowledge of TB.
The international journal of tuberculosis and lung disease: the official journal of the International Union against Tuberculosis and Lung Disease 02/2011; 15(2):228-33, i. · 2.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: A cross sectional study was conducted on 906 apparently healthy camels slaughtered at Akaki and Metehara abattoirs to investigate the pathology of camel tuberculosis (TB) and characterize its causative agents using postmortem examination, mycobacteriological culturing, and multiplex polymerase chain reaction (PCR), region of difference-4 (RD4)-based PCR and spoligotyping. The prevalence of camel TB was 10.04% (91/906) on the basis of pathology and it was significantly higher in females (χ(2) = 4.789; P = 0.029). The tropism of TB lesions was significantly different among the lymph nodes (χ(2) = 22.697; P = 0.002) and lung lobes (χ(2) = 17.901; P = 0.006). Mycobacterial growth was observed in 34% (31/91) of camels with grossly suspicious TB lesions. Upon further molecular characterization using multiplex PCR, 68% (21/31) of the colonies showed a positive signal for the genus Mycobacterium, of which two were confirmed Mycobacterium bovis (M. bovis) by RD4 deletion typing. Further characterization of the two M. bovis at strains level revealed that one of the strains was SB0133 while the other strain was new and had not been reported to the M. bovis database prior to this study. Hence, it has now been reported to the database, and designated as SB1953. In conclusion, the results of the present study have shown that the majority of camel TB lesions are caused by mycobacteria other than Mycobacterium tuberculosis complex. And hence further identification and characterization of these species would be useful towards the efforts made to control TB in camels.
PLoS ONE 01/2011; 6(1):e15862. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: There is little information concerning community-based prevalence of latent tuberculosis infection (LTBI) using T-cell based interferon-γ (IFN-γ) release assays (IGRAs), particularly in TB endemic settings. In this study, the prevalence of LTBI in the Afar pastoral community was assessed using QuantiFERON-TB Gold In-Tube (QFTGIT) and tuberculin skin tests (TST).
A community-based cross-sectional survey of LTBI involving 652 apparently healthy adult pastoralists was undertaken in the pastoral community of Amibara District of the Afar Region between April and June 2010.
The prevalence of LTBI was estimated as 63.7% (363/570) using QFTGIT at the cut-off point recommended by the manufacturer (≥0.35 IU/ml IFN-γ), while it was 74.9% (427/570) using a cut-off point≥0.1 IU/ml IFN-γ. The QFTGIT-based prevalence of LTBI was not significantly associated with the gender or age of the study participants. However, the prevalence of LTBI was 31.2% (183/587) using TST at a cut-off point≥10 mm of skin indurations, and it was higher in males than females (36.8% vs. 23.5%, X2=11.76; p<0.001). There was poor agreement between the results of the tests (k=0.098, 95% CI, 0.08-0.13). However, there was a positive trend between QFTGIT and TST positivity (X2=96.76, P<0.001). Furthermore, individuals with skin indurations≥10 mm were 13.6 times more likely to have positive results using QFTGIT than individuals with skin indurations of 0 mm (adjusted OR=13.6; 95%CI, 7.5 to 24.7, p<0.001).
There is currently no agreed gold standard for diagnosis of LTBI. However, the higher prevalence of LTBI detected using QFTGIT rather than TST suggests that QFTGIT could be used for epidemiological studies concerning LTBI at the community level, even in a population unreactive to TST. Further studies of adults and children will be required to assess the effects of factors such as malnutrition, non-tuberculosis mycobacterial infections, HIV and parasitic infections on the performance of QFTGIT.
[show abstract][hide abstract] ABSTRACT: Afar pastoralists live in the northeast of Ethiopia, confined to the most arid part of the country, where there is least access to educational, health and other social services. Tuberculosis (TB) is one of the major public health problems in Afar region. Lack of knowledge about TB could affect the health-seeking behaviour of patients and sustain the transmission of the disease within the community. In this study, we assessed the knowledge and perception of apparently healthy individuals about pulmonary tuberculosis (PTB) in pastoral communities of Afar.
Between March and May 2009, a community-based cross-sectional questionnaire survey involving 818 randomly selected healthy individuals was conducted in pastoral communities of Afar region. Moreover, two focus group discussions (FGDs), one with men and one with women, were conducted in each of the study area to supplement the quantitative study.
The majority (95.6%) of the interviewees reported that they have heard about PTB (known locally as "Labadore"). However, the participants associated the cause of PTB with exposure to cold air (45.9%), starvation (38%), dust (21.8%) or smoking/chewing Khat (Catha edulis) (16.4%). The discussants also suggested these same factors as the cause of PTB. All the discussants and the majority (74.3%) of the interviewees reported that persistent cough as the main symptom of PTB. About 87.7% of the interviewees and all the discussants suggested that PTB is treatable with modern drugs. All the discussants and the majority (95%) of the interviewees mentioned that the disease can be transmitted from a patient to another person. Socio-cultural practices, e.g. sharing cups (87.6%), and house type (59.8%) were suggested as risk factors for exposure to PTB in the study areas, while shortage of food (69.7%) and chewing khat (53.8%) were mentioned as factors favouring disease development. Almost all discussants and a considerable number (20.4%) of the interviewees thought that men were the highest risk group to get PTB as well as playing a major role in the epidemiology of the disease.
The findings indicate that pastoral communities had basic awareness about the disease. Nevertheless, health education to transform their traditional beliefs and perceptions about the disease to biomedical knowledge is crucial.
BMC Public Health 04/2010; 10:187. · 2.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: At the dawn of the third millennium, while the control of the second biggest infectious killer in the world (tuberculosis [TB]) is an international priority, millions of pastoralist communities in the Horn of Africa are struggling to access TB care. Prompt diagnosis and treatment of pastoralist TB patients remain to be a challenge in TB control programs in many countries in this region, where pastoralism is a common means of livelihood. Better understanding of community perceptions of TB and its management could help identify reasons for the delay in diagnosis of TB among pastoral communities. The aim of this study is to explore barriers delaying diagnosis among pastoralist TB patients in the Somali Regional State (SRS) of Ethiopia.
A qualitative study, including 19 respondents was conducted in the SRS of Ethiopia. Participatory Rural Appraisal (PRA) and informal interview techniques were employed to explore pastoralists' migration patterns, their perceptions of TB and their access to TB services. The influence of these factors on the delay of TB patients in receiving biomedical diagnosis was then assessed.
We found that lack of access to formal health services as well as traditional beliefs leading to self treatment were barriers to prompt bio-medical diagnosis of TB among pastoralist TB patients in the SRS of Ethiopia. This study highlights that limited access to TB control programs is the most important barrier in early seeking of biomedical diagnosis of TB among pastoral communities with nomadic pastoralist being the most affected.
Diagnostic and treatment facilities should be established in strategic villages that pastoralist can reach in both dry and wet seasons. Such facilities may alleviate the observed long distance to health facilities and thus long delay in diagnosis of TB. This strategy should be compounded with a community based TB control approach, whereby basic medical training on TB management such as provision of health education, drug distribution and observations is provided to local traditional healers and religious leaders. This approach may improve pastoralists' perceptions of TB, hence eliminating the observed traditional believes associated with TB in pastoralists' context of the SRS.
[show abstract][hide abstract] ABSTRACT: Currently, T-cell based gamma interferon (IFNγ) release assays (IGRAs) are acknowledged as the best methods available for the screening of latent tuberculosis infection (LTBI) and also as aid for the diagnosis of active tuberculosis (TB). To our information, the performance of these diagnostic tests has not been evaluated in Ethiopia. Therefore, the intent of this study was to evaluate the performance of QuantiFERON-TB Gold In-Tube (QFTGIT) in patients clinically suspected of active pulmonary TB (PTB) as well as in healthy subjects prior to its utilization for the epidemiological study of active TB and LTBI in Afar pastoralists.
The sensitivity of QFTGIT was evaluated in 140 subjects who were clinically suspected of PTB using the cut-off value recommended by the manufacturer (≥ 0.35 IU/ml) and disease-specific cut-off value. Sputum culture result was used as a gold standard. The specificity of the test was evaluated both in patients and in 55 tuberculin skin test (TST) negative healthy subjects.
Out of the 140 study participants, 37 (26.4%) were positive for active PTB by culture. Out of the 37 subjects who had positive results by culture, 6 individuals were HIV-seropositive. Out of the 103 subjects who were negative by culture, 6 subjects had indeterminate results and 21 were HIV-seropositive. The performance of the test was assessed using data from 107 (31 culture positive and 76 culture negative) individuals who were clinically suspected of PTB and HIV-seronegatives. Using the manufacturer recommended cut-off value, the sensitivity of the test was 64.5% (20/31), while its specificity was 36.8% (28/76). The sensitivity of the test was increased to 77.4%, while the specificity was reduced to 23.7% using a cut-off value ≥ 0.1 IU/ml of IFNγ as disease-specific cut-off value. In TST negative healthy subjects, the specificity of the test was 58.2%.
Our findings revealed a low sensitivity of QFTGIT in the diagnosis of Mycobacterium tuberculosis (Mtb) infection in the present study area using the cut-off value recommended by the manufacturer. Nevertheless, the sensitivity increased from 64.5% to 77.4% by lowering the cut-off value recommended by the manufacturer to ≥ 0.1 IU/ml of IFNγ level. Hence, it is of practical importance to evaluate the performance of QFTGIT in population under different settings prior to its application either for the diagnosis of active TB or LTBI.
[show abstract][hide abstract] ABSTRACT: 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.
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.
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.
BMC Veterinary Research 01/2010; 6:28. · 1.86 Impact Factor
[show abstract][hide abstract] ABSTRACT: Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) is one of the most important infectious diseases globally. Immune effector mechanisms that lead to protection or development of clinical disease are not fully known. It is generally accepted that cell-mediated immunity (CMI) plays a pivotal role in controlling Mtb infection, whereas antibody responses are believed to have no protective role. This generalization is based mainly on early classical experiments that lacked standard protocols, and the T helper type 1 (Th1)/Th2 paradigm. According to the Th1/Th2 paradigm Th1 cells protect the host from intracellular pathogens, whereas Th2 cells protect form extracellular pathogens. During the last two decades, the Th1/Th2 paradigm has dominated not only our understanding of immunity to infectious pathogens but also our approach to vaccine design. However, the last few years have seen major discrepancies in this model. Convincing evidence for the protective role of antibodies against several intracellular pathogens has been established. Studies of B cell-deficient mice, severe combined immunodeficiency (SCID) mice, passive immunization using monoclonal (mAb) and polyclonal antibodies and immune responses against specific mycobacterial antigens in experimental animals reveal that, in addition to a significant immunomodulatory effect on CMI, antibodies play an essential protective role against mycobacterial infections. In this review, our current understanding of the essential role of antibodies during Mtb infections, limitations of the Th1/Th2 model and the unfolding interdependence and mutual regulatory relationships between the humoral and CMI will be presented and discussed.
[show abstract][hide abstract] ABSTRACT: Tuberculosis (TB) is a major public health problem in the Horn of Africa with Ethiopia being the most affected where TB cases increase at the rate of 2.6% each year. One of the main contributing factors for this rise is increasing transmission due to large number of untreated patients, serving as reservoirs of the infection within the communities. Reduction of the time between onset of TB symptoms to diagnosis is therefore a prerequisite to bring the TB epidemic under control. The aim of this study was to measure duration of delay among pastoralist TB patients at TB management units in Somali Regional State (SRS) of Ethiopia.
A cross sectional study of 226 TB patients with pastoralist identity was conducted in SRS of Ethiopia from June to September 2007. Patients were interviewed using questionnaire based interview. Time between onset of TB symptoms and first visit to a professional health care provider (patient delay), and the time between first visits to the professional health care provider to the date of diagnosis (medical provider's delay) were analyzed. Both pulmonary and extrapulmonary TB patients were included in the study.
A total of 226 pastoralist TB patients were included in this study; 93 (41.2%) were nomadic pastoralists and 133 (58.8%) were agro-pastoralists. Median patient delay was found to be 60 days with range of 10-1800 days (83 days for nomadic pastoralists and 57 days for agro-pastoralists). Median health care provider's delay was 6 days and median total delay was 70 days in this study. Patient delay constituted 86% of the total delay. In multivariate logistic regression analysis, nomadic pastoralism (aOR. 2.69, CI 1.47-4.91) and having low biomedical knowledge on TB (aOR. 2.02, CI 1.02-3.98) were significantly associated with prolonged patient delay. However, the only observed risk factor for very long patient delay >120 days was distance to health facility (aOR.4.23, CI 1.32-13.54). Extra-pulmonary TB was the only observed predictor for health care providers' delay (aOR. 3.39, CI 1.68-6.83).
Patient delay observed among pastoralist TB patients in SRS is one of the highest reported so far from developing countries, exceeding two years in some patients. This long patient delay appears to be associated with patient's inadequate knowledge of the disease and distance to health care facility with nomadic pastoralists being the most affected. Regional TB control programmes need to consider the exceptional circumstances of pastoralists, to maximise their access to TB services.
BMC Public Health 01/2009; 9:5. · 2.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: One-third of the world population is estimated to have Mycobacterium tuberculosis infection. Accurate and timely identification of infected individuals is critical for treatment and control. The current diagnostic methods lack the desired sensitivity and specificity, require sophisticated equipment and skilled workforce or take weeks to yield results. Diagnosis of extrapulmonary TB, TB-HIV co-infection, childhood TB and sputum smear-negative pulmonary TB pose serious challenges. Interest in developing serodiagnostic methods is increasing because detection of antibody is rapid, simple and relatively inexpensive, and does not require a living cell for detection. Three types of tests, namely screening tests to overcome diagnostic delay, specific tests for diagnosis of extrapulmonary TB and other bacteriologically negative cases, and tests for vaccine-induced immunity need critical consideration. Several factors must be considered to develop serodiagnostic methods for TB. Antigen recognition by infected individuals is highly heterogeneous due to stage of disease, differences in HLA types, strain of the bacilli, health of the patient and bacillary load. With advances in molecular biological techniques, a number of novel antigens have been identified. Some of these antigens have proven valuable in detecting specific antibodies in some of the most challenging TB patients. The best example is a fusion protein containing several M. tuberculosis proteins (e.g. CFP-10, MTB8, MTB48, MTB81 and the 38-kDa protein) which showed encouraging results in detecting antibodies in sera of patients, including TB-HIV co-infection. This review presents progress made in the serodiagnosis of TB during the last decade.
Scandinavian Journal of Immunology 01/2007; 66(2-3):176-91. · 2.20 Impact Factor