Characterization of virulence factors of Salmonella isolated from human stools and street food in urban areas of Burkina Faso.

BACKGROUND: This study was undertaken to identify and functionally characterize virulence genes from Salmonella isolates in street food and stool cultures. From February 2017 to May 2018, clinical and food Salmonella strains were isolated in three regions in Burkina Faso. Salmonella was serotyped according to the White-Kauffmann-Le Minor method, and polymerase chain reaction (PCR) was used to detec invA, spvR, spvC, fimA and stn virulence genes commonly associated with salmonellosis in Sub-Saharan Africa. RESULTS: A total of 106 Salmonella isolates (77 human stools; 14 sandwiches) was analyzed using a serological identification with an O-group test reagent. The presence of Salmonella was confirmed in 86% (91/106) of the samples were reactive (OMA-positive/OMB-positive). Salmonella serogroup O:4,5 was the most common serogroup detected (40%; 36/91). Salmonella Enteritidis and Typhimurium represented 5.5% (5/91) and 3.3% (3/91), respectively and were identified only from clinical isolates. Furthermore, 14 serotypes of Salmonella (12/91 human strains and 2/15 sandwich strains) were evocative of Kentucky/Bargny serotype. For the genetic profile, 66% (70/106) of the Salmonella had invA and stn genes; 77.4% (82/106) had the fimA gene. The spvR gene was found in 36.8% (39/106) of the isolates while 48.1% (51/106) had the spvC gene. Among the identified Salmonella Enteritidis and Salmonella Typhimurium isolated from stools, the virulence genes detected were invA (3/5) versus (2/3), fimA (4/5) versus (3/3), stn (3/5) versus (2/3), spvR (4/5) versus (2/3) and spvC (3/5) versus (2/3), respectively. CONCLUSION: This study reports the prevalence of Salmonella serotypes and virulence genes in clinical isolates and in street foods. It shows that food could be a significant source of Salmonella transmission to humans. Our results could help decision-making by the Burkina Faso health authority in the fight against street food-related diseases, in particular by training restaurateurs in food hygiene.

Epidemiology and microscopic diagnosis of tuberculosis in pigs and small ruminants slaughtered at Bobo-Dioulasso abattoir, Burkina Faso.

Bovine tuberculosis (bTB) is a zoonotic, infectious, chronic and contagious disease, caused by Mycobacterium bovis that mainly affects cattle. This pathology has a negative impact on animals and animal products trade. Unfortunately, in Burkina Faso where agriculture and livestock sectors represent around 80% of the socio-economic activities, the real situation of the disease is not well known especially in small ruminants and swine. Thus, our study focused on both the epidemiology and the microbiological diagnosis of tuberculosis (TB) in small ruminants and pigs slaughtered at Bobo-Dioulasso abattoir. A prospective study was conducted between August 2017 and December 2017. Epidemiological data collection was performed during routine meat inspection; moreover, samples were taken and transported to the Bacteriology laboratory of Centre Muraz for microbiological analyses. This diagnosis consisted in search of Acid Fast Bacilli (AFB) using the hot Ziehl-Neelsen staining. Out of a total of 14 648 small ruminants and 2430 pigs slaughtered during the study period, 156 and 17 had lesions suggestive of bTB with prevalence of 1.07% and 0.7%, respectively. Females and those between 2 and 4 years old were mainly infected. The most affected organs were: lungs, liver, spleen and lymph nodes. Finally, microscopy revealed 43.35% (75/173) of positive cases for AFB. These results confirm the presence of bTB in small ruminants and pigs in Burkina Faso. Efforts must still be made in the fight against this zoonosis in order to limit its economic and public health impacts.

[Bochdalek hernia with intrathoracic liver herniation in an adult patient treated with robotic surgery: a case report]. / Hernie de Bochdalek avec issue hépatique en intrathoracique chez un adulte, traitée par voie robotique: à propos d´un cas.

This study reports the case of a 45-year-old female patient presenting with isolated pain in the right hypochondrium radiating to the back, evolving over the last several years. The patient had no medical history. Physical examination was normal. Computed tomography (CT) scan showed right-sided diaphragmatic hernia (Bochdalek hernia) with a part of the liver protrunding into the chest. The patient underwent robotic surgery. The postoperative course was simple. The patient had no recurrence at 1-year follow-up. Bochdalek hernia with intrathoracic liver herniation is rare in adult patients. It can be treated by robotic surgery.

Clinical presentation, outcomes and factors associated with mortality: A prospective study from three COVID-19 referral care centres in West Africa.

OBJECTIVES: The overall death toll from COVID-19 in Africa is reported to be low but there is little individual-level evidence on the severity of the disease. This study examined the clinical spectrum and outcome of patients monitored in COVID-19 care centres (CCCs) in two West-African countries. METHODS: Burkina Faso and Guinea set up referral CCCs to hospitalise all symptomatic SARS-CoV-2 carriers, regardless of the severity of their symptoms. Data collected from hospitalised patients by November 2020 are presented. RESULT: A total of 1,805 patients (64% men, median age 41 years) were admitted with COVID-19. Symptoms lasted for a median of 7 days (IQR 4-11). During hospitalisation, 443 (25%) had a SpO2 < 94% at least once, 237 (13%) received oxygen and 266 (15%) took corticosteroids. Mortality was 5% overall, and 1%, 5% and 14% in patients aged <40, 40-59 and ≥60 years, respectively. In multivariable analysis, the risk of death was higher in men (aOR 2.0, 95% CI 1.1; 3.6), people aged ≥60 years (aOR 2.9, 95% CI 1.7; 4.8) and those with chronic hypertension (aOR 2.1, 95% CI 1.2; 3.4). CONCLUSION: COVID-19 is as severe in Africa as elsewhere, and there must be more vigilance for common risk factors such as older age and hypertension.

Predictors of severe hypoxemia among COVID-19 patients in Burkina Faso (West Africa): Findings from hospital based cross-sectional study.

INTRODUCTION: COVID-19 is one of the world's major health crises. The objective of this study was to determine the predictive factors of severe hypoxemia in patients hospitalized in COVID-19 health facilities in Burkina Faso. PATIENTS AND METHOD: This study was a hospital-based cross-sectional study. The data collected relate to the period of the first wave of the epidemic (March 9 to June 30, 2020). All patients hospitalized for COVID-19 in the requisitioned health facilities of Ouagadougou were included in this study. Predictors of severe hypoxemia were identified using a multivariate logistic regression model. RESULTS: During the study period, 442 patients were included, representing 45.7% of the total number of positive patients in the entire country. The most common co-morbidities were diabetes (55; 12.4%) and arterial hypertension (97; 21.9%). Severe hypoxemia (SpO2 < 90%) was observed in 64 patients (14.5%). Age over 65 years (OR = 8.24; 95% CI: 2.83-24.01) and diabetes (OR = 2.43; 95% CI: 1.17-5.06) were the predictors for occurrence of severe hypoxemia in multivariate analysis. CONCLUSION: The predictive factors of COVID-19 are similar in African and Caucasian populations. The surveillance of COVID-19 in risk groups should be strengthened to reduce their morbidity and mortality.

Infection of highly insecticide-resistant malaria vector Anopheles coluzzii with entomopathogenic bacteria Chromobacterium violaceum reduces its survival, blood feeding propensity and fecundity.

BACKGROUND: This is now a concern that malaria eradication will not be achieved without the introduction of novel control tools. Microbiological control might be able to make a greater contribution to vector control in the future. The interactions between bacteria and mosquito make mosquito microbiota really promising from a disease control perspective. Here, the impact of Chromobacterium violaceum infections, isolated from both larvae and adult of wild-caught Anopheles gambiae sensu lato mosquitoes in Burkina Faso, was evaluated on mosquito survival, blood feeding and fecundity. METHODS: To assess entomopathogenic effects of C. violaceum infection on mosquitoes, three different types of bioassays were performed in laboratory. These bioassays aimed to evaluate the impact of C. violaceum infection on mosquito survival, blood feeding and fecundity, respectively. During bioassays mosquitoes were infected through the well-established system of cotton ball soaked with 6% glucose containing C. violaceum. RESULTS: Chromobacterium violaceum kills pyrethroid resistant Anopheles coluzzii (LT80 of 8.78 days ± 0.18 at 108 bacteria cell/ml of sugar meal). Interestingly, this bacterium had other negative effects on mosquito lifespan by significantly reducing (~ 59%, P < 0.001) the mosquito feeding willingness from day 4-post infection (~ 81% would seek a host to blood feed) to 9- day post infection (22 ± 4.62% would seek a host to blood feed). Moreover, C. violaceum considerably jeopardized the egg laying (~ 16 eggs laid/mosquito with C. violaceum infected mosquitoes vs ~ 129 eggs laid/mosquito with control mosquitoes) and hatching of mosquitoes (a reduction of ~ 22% of hatching rate with C. violaceum infected mosquitoes). Compared to the bacterial uninfected mosquitoes, mosquitoes infected with C. violaceum showed significantly higher retention rates of immature eggs and follicles. CONCLUSION: These data showed important properties of Burkina Faso C. violaceum strains, which are highly virulent against insecticide-resistant An. coluzzii, and reduce both mosquito blood feeding and fecundity propensities. However, additional studies as the sequencing of C. violaceum genome and the potential toxins secreted will provide useful information render it a potential candidate for the biological control strategies of malaria and other disease vectors.

[Vancomycin-based Lowenstein-Jensen selective medium for reducing contamination of mycobacterial cultures by spore-forming bacteria]. / Milieu sélectif de Lowenstein-Jensen à base de vancomycine pour la réduction des contaminations de cultures de mycobactéries par les bactéries sporulantes.

INTRODUCTION: despite the development of new methods, culture on solid medium is the gold standard for the diagnosis of tuberculosis. However, this method is associated with increased rates of contamination of cultures by spore-forming bacteria. These bacteria are generally sensitive to vancomycin and to a combinsation of vancomycin, colistin, nystatin, and trimethoprim (VCNT). The purpose of this study was to assess the effectiveness of VCNT-based selective Lowenstein-Jensen (LJ) medium in reducing contamination of cultures by spore-forming bacteria. METHODS: sputum samples, collected from the 120 TB and non-TB patients included in the study between October 2016 and May 2017, were decontaminated with the modified Petroff method. Decontamination pellets were inoculated onto conventional LJ media and selective VCNT-based LJ medium containing 10µg/ml vancomycin. Fifteen strains of spore-forming bacteria were inoculated onto the same media in order to assess their sensitivity to VCNT. RESULTS: the contamination of cultures on VCNT-based LJ medium containing 10µg/ml of vancomycin and LJ medium were 11.66% (14/120) and 39.16% (47/120) with p <0.0001, respectively. Sensitivity of spore-forming bacteria to VCNT decreased with the increasing of culture incubation time. CONCLUSION: VCNT-based selective LJ medium containing 10µg/ml vancomycin led to a significant reduction in the rate of culture contamination. This environment could contribute to improve the quality of mycobacterial cultures and thus bacteriological diagnosis of tuberculosis.

[Cancer of the vulva: Diagnostic stages, treatment and survival in a country with limited resources (Burkina Faso)]. / Cancer de la vulve : stades diagnostiques, traitement et survie dans un pays aux ressources limitées (Burkina Faso).

INTRODUCTION: Vulvar cancer is rare and belatedly diagnosed in Africa. We describe its diagnostic stages, therapeutic and evolution features in a country with limited resources. METHODOLOGY: Forty-seven cases of vulvar cancer diagnosed between 2013 and 2018 in Burkina Faso, were analyzed retrospectively. The diagnostic stages, therapeutic and evolution terms were considered. Survival was calculated through the Kaplan Meier Method and compared using the Logrank technique. RESULTS: Stages IA and IB accounted for 10.6%. Radiotherapy was not available and chemotherapy was done in 9 cases. Full vulvectomy with bilateral inguino-femoral dissection was performed in 11 cases. Average survival was 41 months with a median of 52 months. The difference in survival according to the diagnostic stages were highly significant statistically (P=0.000). DISCUSSION: Cancer of the vulva is rare and raises major therapeutic difficulties in countries with limited resources. Surgery is the only affordable weapon. Evolution would be better if radiochemotherapy was possible. CONCLUSION: Radiochemotherapy cannot be done due to the lack of a radiotherapy unit and the high cost of cytotoxics. Surgery is largely palliative and/or mutilating. Survival is modest. An early diagnosis could help promote conserving treatments.

Why oral antiseptic mouth rinsing before sputum collection cannot reduce contamination rate of mycobacterial culture in Burkina-Faso.

BACKGROUND: Tuberculosis (TB) diagnosis by culture in most resource-limited settings is hampered by high contamination rate varying up to 31%. Reduction of oral microorganism loads by mouth rinse with antiseptic before sputum collection showed a reduction of contamination. Moreover, knowing the characteristic of residual contaminant microorganisms would be an asset to understand contamination issues. OBJECTIVES: The aim of this study was to evaluate the effects of mouth rinsing with chlorhexidine on mycobacteria culture contaminations and to characterize morphologically the residual contaminants. METHODS: We consecutively included 158 patients in a TB center. Each of them supplied two sputa: The first before mouth rinse, and the second after 60sec of mouth rinsing with chlorhexidine (0.1%). Petroff method and Lowenstein-Jensen media were used for sputum decontamination and inoculation respectively. The contamination rates were compared, and the type of residual contaminants were characterized and compared. RESULTS: The contamination rate did not differ before and after the mouth rinse (respectively 58/150 (39 %) vs 61/150 (41 %), p=0.7). The major residual contaminants were Gram positive spore forming bacteria (94%). CONCLUSION: Chlorhexidine mouth rinsing before sputum collection did not reduce mycobacterial culture contamination rate. This is probably due to spore forming bacteria, highlighted as major residual contaminants.

Ectopic pheochromocytoma or paraganglioma of the ZUCKERKANDL organ: A case report and review of the literature.

INTRODUCTION: Paraganglioma of the ZUCKERKANDL organ are rare. Diagnosis is based on clinical, radiological and biological arguments. We report a case to describe our surgical procedure and insist on the necessity of preoperative diagnosis. PRESENTATION OF CASE: BA, 52-years-old male patient was seen in consultation for left hypochondrium pains. The clinical examination had revealed a painful tumefaction in the left flank and the left hypochondrium. A deep mass was observed, but was difficult to be assessed, due to pain. Abdominal-pelvic CT scan with contrast injection had revealed a tissue mass, suggesting a tumor of the tail of the pancreas. Laparotomy showed this mass was not attached to the tail of the pancreas, and was along the abdominal aorta up to the aortic bifurcation. Upon touching the mass, blood pressure raised up to 240 mmHg. A least mobilization of the mass and the use of nicardipine helped maintain blood pressure below 180mmhg. Dissection was carried out from the aortic bifurcation to the TREITZ's angle and the mass was removed. The follow-ups were characterized by low blood pressure a few minutes following the resection of the mass. DISCUSSION: Pheochromocytoma is rare. The Clinical signs, Abdominal-pelvic CT scan and biology are the steps of the preoperative diagnosis. The surgery consists a lumpectomy. The resuscitation determines the patient's prognosis. CONCLUSION: Pheochromocytoma is an unusual mass. Preoperative diagnosis can be difficult in pauci-symptomatic cases. One should consider this in the face of any abdominal mass, so as to improve planning of resuscitation which determines the patient's prognosis.

Giant lipoma of the left mesocolon: Radiological and surgical aspects.

INTRODUCTION: Abdominal masses are common in digestive surgery and gastro-enterology units. However, meso-intestinal lipomas remain rare and lipoma of the left colon uncommon. We report a case of giant lipoma of the left mesocolon whose diagnosis was highly guided by radiological examinations. PRESENTATION OF CASE: A female patient aged 56, consulted for left subcostal abdominal pains. The clinical examination showed an abdominal mass occupying the left hemiabdomen. The abdominal-pelvic CT scan highlighted a large abdominal-pelvic mass in the left abdomen. Abdominal-pelvic MRI revealed a large fatty mass spreading from the front subphrenic space up to the level of the left iliac fossa, non-suspected and compatible with lipoma. FDG-Pet Scan had not revealed pathological fixing. The mass appeared like a total gap space. Exploratory surgery revealed a lipoma mass in the left mesocolon. Hemicolectomy was performed taking away the mass. Histology confirmed the diagnosis of lipoma and the outcome was favourable. DISCUSSION: Our case represents the fourth case of mesocolon lipoma described in the literature. Imaging, especially TDM and MRI are an important step of the preoperative diagnosis. The surgery consists of either a lumpectomy or a colectomy. CONCLUSION: Lipoma of the left mesocolon is exceptional. Radiological examinations provide most arguments to suggest lipoma. However the organ's diagnosis is provided by surgical exploration and the certainty diagnosis by pathological examination. Treatment is surgical.

Identification of spore-forming bacteria isolated from contaminated Lowenstein Jensen media and effectiveness of Vancomycin to reduce Mycobacterial culture contamination in Burkina-Faso.

The type of commensal microorganisms can influence the efficiency of sputum decontamination for TB diagnosis. A basic characterization of contaminants from LJ contaminated media showed that Gram positive Spore Forming Bacteria (SFB) were the major contaminants. This study aims to identify the species of this contaminants and to evaluate the effectiveness of VCNT at 10 µg of vancomycin to reduce mycobacterial culture contamination mainly linked to SFB. Fifty-three SFB isolated between February 2016 and May 2017 were used. The effectiveness of LJ with VCNT at 10 µg of Vancomycin were evaluated with sputum collected in the same period. SFB had been stored at -20 °C and identified after subculture onto 5% sheep blood Columbia agar and incubated at 37 °C during 24 h. Bacteria cells and isolated colonies were described. API 50CH/B was performed and MALDI-TOF MS was used for external quality control. Thirty- five (66%) isolates representing 4 genera (Bacillus, Paenibacillus, Brevisbacillus and Lysinibacillus) including 10 species were identified. The most important species were Bacillus cereus (30%) and Bacillus licheniformis (21%). Eighteen (34%) isolates were non-reactive Bacillus. The overall contamination rate on LJ with VCNT at 10 µg of vancomycin was statistically lower than which without VCNT (18.7% versus 43.8%) (p = 0.01). The most important SFB identified were B. cereus and B. licheniformis. Almost all identified strains were similar to those currently isolated in fermented traditional food suggesting in part food related contaminants. VCNT containing 10 µg of vancomycin is a good alternative method to reduce mycobacterial culture contamination.

Male breast cancer: diagnosis stages, treatment and survival in a country with limited resources (Burkina Faso).

BACKGROUND: Male breast cancer is a rare and less known disease. Therapeutic modalities affect survival. In Burkina Faso, male breast cancers are diagnosed in everyday practice, but the prognosis at short-, middle-, and long-term remains unknown. The objective of this study is to study the diagnosis stages, therapeutic modalities, and 5-year survival in male breast cancer at the General Surgery Unit of Yalgado Ouedraogo University Hospital from 1990 to 2009. METHODS: A cohort longitudinal study concerning cases of breast cancer diagnosed in man. Survival was assessed using the Kaplan-Meier method and survival curves were compared through the LogRank test. RESULTS: Fifty-one cases of male breast cancer were followed-up, i.e., 2.6% of all breast cancers. Stages III and IV represented 88% of cases. Eleven patients (21.6%) were at metastatic stage. Patients were operated in 60.8% of cases. The surgery included axillary dissection in 25 (80.6%) out of 31 cases. Lumpectomy was performed on 6.5% of patients (2 cases). Fifteen (29.4%) and 11 (21.6%) patients underwent chemotherapy and hormonal therapy, respectively. The FAC protocol was mostly used. Radiation therapy was possible in two cases. The median deadline for follow-up was 14.8 months. A local recurrence was noticed in 3.2% of cases. The overall 5-year survival rate was 49.9%. The median survival was over 5 years for stages I and II. It was 54 down to 36 months for stages III and IV. CONCLUSION: Diagnosis is late. The lack of immunohistochemistry makes it difficult to define the proportion of their hormonal dependence. Surgery is the basic treatment. Five-year survival is slow and the median survival depends on the diagnosis stage. It can be improved through awareness-raising campaigns and the conduct of individual screening.

[Occlusion secondary to congenital internal transmesenteric hernia: about 2 cases]. / Occlusion par hernie interne transmesenterique congénitale: à propos de deux cas.

Internal hernia due to mesenteric defect or transmesenteric hernia is a rare cause of acute intestinal obstruction. Its diagnosis is most often done during surgery. The knowledge of its clinical peculiarities allows the preoperative diagnosis. We here report 2 cases of acute intestinal obstruction secondary to congenital transmesenteric hernia in two adult patients. This study aims to highlight the clinical peculiarities of this rare form of internal hernia.

The emerging threat of pre-extensively drug-resistant tuberculosis in West Africa: preparing for large-scale tuberculosis research and drug resistance surveillance.

BACKGROUND: Drug-resistant tuberculosis (TB) is a global public health problem. Adequate management requires baseline drug-resistance prevalence data. In West Africa, due to a poor laboratory infrastructure and inadequate capacity, such data are scarce. Therefore, the true extent of drug-resistant TB was hitherto undetermined. In 2008, a new research network, the West African Network of Excellence for Tuberculosis, AIDS and Malaria (WANETAM), was founded, comprising nine study sites from eight West African countries (Burkina Faso, The Gambia, Ghana, Guinea-Bissau, Mali, Nigeria, Senegal and Togo). The goal was to establish Good Clinical Laboratory Practice (GCLP) principles and build capacity in standardised smear microscopy and mycobacterial culture across partnering laboratories to generate the first comprehensive West African drug-resistance data. METHODS: Following GCLP and laboratory training sessions, TB isolates were collected at sentinel referral sites between 2009-2013 and tested for first- and second-line drug resistance. RESULTS: From the analysis of 974 isolates, an unexpectedly high prevalence of multi-drug-resistant (MDR) strains was found in new (6 %) and retreatment patients (35 %) across all sentinel sites, with the highest prevalence amongst retreatment patients in Bamako, Mali (59 %) and the two Nigerian sites in Ibadan and Lagos (39 % and 66 %). In Lagos, MDR is already spreading actively amongst 32 % of new patients. Pre-extensively drug-resistant (pre-XDR) isolates are present in all sites, with Ghana showing the highest proportion (35 % of MDR). In Ghana and Togo, pre-XDR isolates are circulating amongst new patients. CONCLUSIONS: West African drug-resistance prevalence poses a previously underestimated, yet serious public health threat, and our estimates obtained differ significantly from previous World Health Organisation (WHO) estimates. Therefore, our data are reshaping current concepts and are essential in informing WHO and public health strategists to implement urgently needed surveillance and control interventions in West Africa.

[Tourniquets, a drama in the infant: about 3 cases]. / Les garrots de prélèvement, un drame chez le nourrisson: à propos de 3 cas.

The time limit for the removal of a tourniquet is short; any delay in tourniquet deflation, especially if it exceeds the 3 hour limit, exposes to amputation hazards. Our objective was to report three cases of ischemic limb gangrene, caused by having forgotten to take a tourniquet off after a blood sampling, to inform healthcare professionals about the risk associated with that negligence. We encountered 3 cases of infants (2 three-month-old infants and 1 five-month-old infant), hospitalized in intensive care unit of Yalgado Ouédraogo University Hospital for upper-left limb swelling. Their medical history shows that there was a delay in tourniquet deflation after a blood sampling of 24 hours in two cases and of 48 hours in one case. Physical examination revealed a diffuse edema associated with upper limb gangrene spread to the mid-third of the upper arm, abolition of the ulnar and radial pulse as well as loss of sensation in the hand in 2 cases. In one case clinical signs were attenuated. The diagnosis of ischemic limb gangrene was confirmed in all cases. Laboratory examinations were normal. Two cases needed urgent trans-humeral amputation and one case needed debridement plus amputation of four fingers. The evolution was simple in all cases. Iatrogenic dry gangrene caused by a delay in tourniquet removal should never happen at hospitals. This can be guaranteed only by tightening up health management and by performing regular and accurate patient monitoring.

Mycobacterium tuberculosis: ecology and evolution of a human bacterium.

Some species of the Mycobacterium tuberculosis complex (MTBC), particularly Mycobacterium tuberculosis, which causes human tuberculosis (TB), are the first cause of death linked to a single pathogen worldwide. In the last decades, evolutionary studies have much improved our knowledge on MTBC history and have highlighted its long co-evolution with humans. Its ability to remain latent in humans, the extraordinary proportion of asymptomatic carriers (one-third of the entire human population), the deadly epidemics and the observed increasing level of resistance to antibiotics are proof of its evolutionary success. Many MTBC molecular signatures show not only that these bacteria are a model of adaptation to humans but also that they have influenced human evolution. Owing to the unbalance between the number of asymptomatic carriers and the number of patients with active TB, some authors suggest that infection by MTBC could have a protective role against active TB disease and also against other pathologies. However, it would be inappropriate to consider these infectious pathogens as commensals or symbionts, given the level of morbidity and mortality caused by TB.