Mycobacterium bovis in humans and M. tuberculosis in animals in Nigeria: an overview from 1975-2014.

Zoonotic transmission of mycobacteria between humans and other animal species is an important aspect of the epidemiology of tuberculosis (TB) in regions of the world where the burden of the disease in humans and other animals is high. This is particularly important in areas in which sociocultural factors increase the possibility for interspecies transmission of different mycobacteria. Carrying out a review of the published literature involving laboratory-confirmed TB cases (by culture) and/or biochemical and molecular identification, we described the presence of Mycobacterium bovis and M. tuberculosis infections in humans and animals from 1975 to 2014. Overall, 1693 isolates of M. tuberculosis complex and other mycobacteria were identified and reported, of which 1131 represented M. tuberculosis, 286 represented M. bovis, 71 represented M. africanum, and 205 represented other mycobacteria. Importantly, 1.3% (15/1131) of the M. tuberculosis isolates reported were identified in cattle, while 8.0% (23/286) of the M. bovis isolates reported were isolated from humans. We suggest that representative sampling of TB cases in both hosts, studied by molecular identification tools, will help significantly in deciphering ongoing transmission between animals and humans in both directions and will enhance TB control in Nigeria.

Isolation of Mycobacterium tuberculosis from livestock workers and implications for zooanthroponotic transmission in Ibadan, South-western Nigeria.

INTRODUCTION: Tuberculosis (TB) remains a public health problem in sub-Saharan Africa coupled with dearth of information about the disease among livestock workers at risk of infection. We determined the prevalence of pulmonary TB infection and factors associated with its occurrence among livestock workers in south-western Nigeria. METHODS: A cross-sectional study was conducted using active case-finding among livestock workers with sub-clinical pulmonary TB between August 2014 and March 2015. Sputum samples were cultured and subjected to a two-step multiplex-PCR technique based on genus-typing and genomic regions-of-difference. Interviewer-administered questionnaire was utilized in assessing worker's TB related knowledge and practices. Data were analysed using STATA 12. RESULTS: Overall, 206 livestock workers (traders = 136; butchers = 70) were screened; 5.1% (7/136) of the traders and 7.1% (5/70) of the butchers had positive mycobacterial cultures. Molecular techniques identified one Mycobacterium tuberculosis with six non-tuberculous mycobacteria (NTM) from the traders and four M. tuberculosis with one NTM from the butchers.Participants within the age range of 50 years and above were at higher risk of being infected with TB (OR = 7.7; 95%CI:1.7-35.6) and majority had poor knowledge and practices regarding TB. CONCLUSIONS: We confirmed M. tuberculosis as the cause of pulmonary TB among the livestock workers, with implications for zooanthroponotic transmission of the disease along the human-animal ecosystem interface in Nigeria.

Brucellosis in Sub-Saharan Africa: Current challenges for management, diagnosis and control.

Brucellosis is a highly contagious zoonosis caused by bacteria of the genus Brucella and affecting domestic and wild mammals. In this paper, the bacteriological and serological evidence of brucellosis in Sub-Saharan Africa (SSA) and its epidemiological characteristics are discussed. The tools available for the diagnosis and treatment of human brucellosis and for the diagnosis and control of animal brucellosis and their applicability in the context of SSA are presented and gaps identified. These gaps concern mostly the need for simpler and more affordable antimicrobial treatments against human brucellosis, the development of a B. melitensis vaccine that could circumvent the drawbacks of the currently available Rev 1 vaccine, and the investigation of serological diagnostic tests for camel brucellosis and wildlife. Strategies for the implementation of animal vaccination are also discussed.

Prevalence and direct economic losses from bovine tuberculosis in makurdi, Nigeria.

A retrospective study was conducted to investigate the prevalence of bovine tuberculosis and direct economic losses (DEL) from tuberculosis in cattle slaughtered in Makurdi abattoirs from 2008 to 2012, using abattoir records obtained from the Ministry of Agriculture and Natural Resources. Out of 61654 cattle slaughtered during the study period 1172 (1.90%) were positive for tuberculosis lesions. The annual prevalence of bovine tuberculosis ranges from 0.90% in 2008 to 4.04% in 2012. There was significant (P < 0.05) difference in annual prevalence of bovine tuberculosis. It was also observed that there was no seasonal difference in the prevalence of bovine tuberculosis. A total of 1935 affected organs by BTB weighing 3046.50 kg, amounting to 2.91 × 10(6) Naira (1.82 × 10(4) USD), were condemned within the study period. Seasonal variation in organ condemnation due to bovine tuberculosis was significantly different (Mann-Whitney U statistics = 774 × 10(3), P = 0.034). It was concluded that bovine tuberculosis is prevalent in Makurdi and accounts for heavy economic losses due to condemnation of edible organs.

Seroprevalence and risk factors of brucellosis in goats in selected states in Nigeria and the public health implications.

Available reports on brucellosis in Nigeria are largely confined to cattle while it is believed that other ruminants like sheep and goats are equally exposed to the disease. To have an insight into the role of goats in the epidemiology of brucellosis in Nigeria, we conducted a cross-sectional study between June 2011 and May 2013 to determine the seroprevalence of brucellosis in goats in some selected states in Nigeria. Serum samples were collected from goats at different locations and tested for antibodies to Brucella spp using the Rose Bengal Test (RBT), samples positive by RBT were further subjected to Competitive Enzyme Linked Immunosorbent Assay (cELISA). Data collected to determine risk factors were also analysed using chi-square and logistics regression statistics. Out of a total of 2827 samples tested from the different states (Benue = 331; Borno =195; Oyo = 2155; Sokoto = 146), we recorded an overall seroprevalence of 2.83% (Benue = 17.30%; Borno = 2.05%; Oyo = 0.60% and Sokoto = 0.00%) by RBT. The cELISA further supported 9.45% (7/74) of the total RBT positive samples. Logistic regression analysis showed that the location (p = 0.004) and source (p < 0.0001); are probable risk factors to be considered in the epidemiology of brucellosis with sex (p = 0.179); age (p = 0.791) and breed (p = 0.369) not playing any major role. Our findings reveal a relatively low seroprevalence of brucellosis among goats screened except for Benue State. Since most of the goats sampled in the present study were from the abattoirs, further farm level investigations are required to determine the role of goats in the epidemiology of brucellosis in Nigeria since they share common environment with sheep and cattle that are natural hosts of Brucella species which are of major public health threat.

Mycobacterium africanum and nontuberculous mycobacteria from fresh milk of pastoral cattle and soft cheese in Oyo State--implications for public health.

BACKGROUND: Milk and.milk products from cattle in tuberculosis endemic countries like Nigeria where pasteurization is not enforced could be a source of health concerns to the consumers. METHODS: We assessed randomly selected fresh milk from pastoral cattle, cheese samples and sour milk (nono) for the presence of Mycobacterium species through cultural isolation, Multiplex Polymerase Chain Reaction (PCR) and PCR-restriction enzyme analysis (PRA)-hsp65. RESULTS: Out of 269 fresh milk, 295 cheese and 150 sour milk samples screened; 8.30%, 0.34% and 0.00%, respectively were positive for Mycobacterium species. Molecular characterization revealed three M. africanum (fresh milk = 2; cheese = 1) and a high prevalence of Non-tuberculous Mycobacterium (NTM; 89.29%) from fresh milk comprising M. gordonae (n = 12), M. fortuitum (n = 4), M. senegalense (n = 7) and M. avium (n = 1). CONCLUSION: The isolation of M. africanum and NTM species from this study is a matter of public health concern considering the practice of pooling milk from different animals and the consumption of unpasteurized milk which characterize most pastoral communities in Nigeria. Given the predominance of NTM in this study, their potential to cause disease in humans should not be ignored. Urgent measures should also be taken to integrate molecular techniques that will differentiate NTM from members of the M. tuberculosis complex in the epidemiology of tuberculosis in order to avoid misdiagnosis in humans and thereby protect public health.

Molecular characterization of Mycobacterium bovis in slaughtered cattle in North-Central Nigeria and the public health implications.

BACKGROUND: The molecular biological techniques of polymerase chain reaction (PCR) are accurate and rapid diagnostic methods in the epidemiology of Mycobacterium species in humans and animals, especially in developing countries. METHODS: In this study, positive cultures from suspected tuberculous lesions of slaughtered cattle from two abattoirs in north-central Nigeria were subjected to a two-step multiplex PCR technique, based on genus typing and genomic regions of difference (RD). RESULTS: Out of 50 suspected tuberculous lesions cultured, 40 isolates were obtained. Based on genus typing, 32 of the isolates were identified as Mycobacterium tuberculosis complex (MTC), one as non-tuberculous Mycobacterium (NTM) and the remaining seven were unclassified. Using genomic RD multiplex PCR, all the 32 isolates initially identified as MTC were further characterized as M. bovis. CONCLUSION: Our findings show that 80% of positive cultures from suspected tuberculous lesions were identified as M. bovis; hence, re-confirming M. bovis as the main cause of bovine tuberculosis in Nigeria. These results give further credence to the use of PCR-based molecular techniques as excellent complementary epidemiological tools in the tracking of bovine tuberculosis, a zoonotic disease of major public health importance in Nigeria.

Mapping of Mycobacterium tuberculosis cases in post-conflict Liberia, 2008-2012: A descriptive and categorical analysis of age, gender and seasonal pattern.

BACKGROUND: Tuberculosis (TB) is a major public health. problem in Liberia and it is among the first five most important infectious diseases. Fourteen years of civil war in Liberia caused a large internal displacement and external migration of its citizens to neighbouring countries such as Guinea, Ivory Coast, Sierra Leone, Ghana and Nigeria. Current spatio-temporal pattern of TB cases in Liberia is essential for identifying risk factors among humans for optimal resource allocation. METHODS: Surveillance data from January, 2008 to December, 2012 were retrieved from two national TB referral hospitals in the country: TB Annex Hospital (TBAH) (Montserrado County) and Ganta TB and Leprosy Rehabilitation Hospital (GTBLRH) (Nimba County). Geographic coordinates of TB patient's locations were captured based on records in the hospital case-files using Global Positioning System (GPS). The coordinates were mapped using Geographic Information Systems (GIS) software. Data on age, gender, date of illness, dry and wet season frequency were used to compute a descriptive and categorical analysis. Kulldorff's spatio-temporal scan statistic was used to identify clusters of TB in the two Counties. RESULTS: A total of 2,890 laboratory-confirmed cases were reported during the study period. There were 1,365 (47.23%) and 1,525 (52.77%) cases from TBAH and GTBLRH respectively. The mean age of patient was 45.19 years ± 19.49 (SD). Of this, 1,450 (50.17%) were male. There was significant association between year of TB occurrence and treatment outcome (χ2 = 14.38; p = 0.006). CONCLUSION: The paper presents TB spatial pattern, summarizing 5-year records of post-conflict surveillance of the disease in Liberia.

Lack of protection against rabies in neighbourhood dogs in some peri-urban and rural areas of Ogun and Oyo states, Nigeria.

BACKGROUND: Rabies is a highly fatal zoonosis that causes severe destruction to the central nervous system and remains underreported in developing countries like Nigeria. OBJECTIVES: The increasing close contact between dogs and their owners or neighbours suggest a need for investigation of the protective level of rabies virus (RABV) antibodies in dogs. METHODS: Sera from 150 apparently healthy neighbourhood dogs from some peri-urban and rural areas of Ogun and Oyo states, southwestern Nigeria were analyzed for the presence of RABV antibodies using the indirect ELISA technique. These dogs were kept as pets, used for hunting or sold for human consumption. RESULTS: The results showed that none of the dogs had optimal RABV antibody titres, 25 (16.7%) had sub-optimal antibody titres while 125 (83.3%) were negative. Detection of sub-optimal RABV antibody levels in these unvaccinated dogs suggests that they might have been exposed to rabies or rabies-related viruses. Data obtained from interviews conducted revealed that 21.3% of the dog owners were informed about rabies but neglected vaccination while 44.7% were uninformed. CONCLUSIONS: We conclude that these dogs lacked protective levels of RABV antibodies and thus constitute a public, health threat. This finding underscores the need for dog anti-rabies vaccination campaigns covering peri-urban and rural areas as well as the promotion of large scale public enlightenment programmes on rabies in Nigeria.

Inhibitory activities of selected south west Nigerian medicinal plants against mycobacterium tuberculosis.

INTRODUCTION: Tuberculosis (TB), an infectious disease prevalent in the tropics especially in Africa and Asia is one of the highest causes of morbidity and mortality and a global concern. With increasing resistance of the pathogen, to existing antituberculosis drugs and the synergy between TB infection and acquired immune deficiency syndrome (AIDS), the need for development of new drugs to cope with the infection is urgent. OBJECTIVE: Extracts from 16 plants identified and selected from the ethnomedicine of the Ijebus in Southwestern Nigeria as remedies for tuberculosis were evaluated for activity against Mycobacterium tuberculosis, in vitro. METHODOLOGY: Plant extracts were screened against clinical isolate of Mycobacterium tuberculosis using agar plate method on Middlebrook 7H11 medium and observed for 12 weeks. RESULTS: The crude aqueous methanol extracts. showed varying degrees of activity at concentrations of 0.025 - 100 mg/mL. Ocimum grattisimum (leaf) demonstrated the highest activity with minimum inhibitory concentration (MIC) of 0.025 mg/mL. Two standard anti-tuberculosis drugs; rifampicin and isoniazid, included in the assay had MIC values of 0.01 mg/mL and 0.0005 mg/mL, respectively. CONCLUSION: The results of the study confirm the ethnopharmacological uses of some of the plants for TB indicating their potential as sources for the discovery of anti-tuberculosis drugs.

Mycobacterium bovis infection in livestock workers in Ibadan, Nigeria: evidence of occupational exposure.

SETTING: Bovine tuberculosis (TB) is endemic in the cattle population in Nigeria. Livestock workers are at risk of Mycobacterium bovis infection and unaware of their health status. OBJECTIVE: To determine the occurrence of pulmonary M. bovis infection among livestock workers. DESIGN: A cross-sectional study of livestock traders was conducted for TB through screening of sputum samples using a simple random sampling method coupled with oral interview on the assumption of sub-clinical pulmonary TB infection. Specimens were cultured, and the isolates analysed using molecular typing techniques. RESULTS: Overall, 10% (7/70) of the livestock traders had a positive culture indicative of M. tuberculosis complex, which were differentiated into M. bovis (n = 2) and M. tuberculosis (n = 5) using deletion typing. Further spoligotyping analyses of the M. bovis and two available M. tuberculosis isolates classified the strains as SB1432 and SB09444 and LAM_10 CAM and T1 using respectively www.mbovis.org and spotclust databases. Prolonged cough and >3 years in the livestock trade were risk factors for infection. CONCLUSION: We confirm that there is undetected pulmonary M. bovis infection among livestock traders in Nigeria. Further studies on the role of occupationally exposed workers in the transmission of M. bovis infection to the larger community are required.

Tuberculosis in humans and cattle in jigawa state, Nigeria: risk factors analysis.

A cross-sectional study was conducted from September 2008 to March 2009 to identify risk factors for BTB in cattle and humans in Jigawa State, Nigeria. A total of 855 cattle belonging to 17 households were subjected to comparative intradermal tuberculin test (CITT) while interviewer-administered questionnaire was used to obtains information on the risk factors. Twenty-two (22) respondent (5%) amongst the families sampled had TB or clinical signs suggestive of TB, while 9 (2%) had reactor cattle in their herds; However, no statistically significant association (P ≥ 0.05) was observed between reactor cattle and human TB cases in the households. The habit of milk and meat consumption was found to be affected by occupation and location of the household residence. None of these risk factors (food consumption, living with livestock in the same house, and presence of BTB-positive cattle) were found to be statistically significant.

Recovery rates of Mycobacterium tuberculosis using five decontamination methods.

Tuberculosis (TB) caused by Mycobacterium tuberculosis remains one of the leading infectious diseases in resource limited countries of the world, including Nigeria. For optimal care of patients with pulmonary TB, effective decontamination methods are required for isolation and identification of M. tuberculosis from other fast growing organisms found in sputum samples of infected patients. Five methods of sputum decontamination including the Petroff, oxalic, bleach, simplified concentration and Kudoh methods were assessed prior to mycobacterial culture. In all, thirty human sputum samples were processed and results analysed after eight weeks of incubation. Overall, there was a significant difference in the growth yield using the different methods (Friedman test statistic, Q(K) = 36.3; P < 0.05). Again, a significant difference (Friedman test statistic, Q(K) = 48.0; P < 0.05) was observed between the valuable and non-valuable yield of mycobacteria. Furthermore, the simplified concentration method had the best performance in terms of pure culture growth/minimal media contamination coupled with a cost benefit ratio of 0.10; the bleach method being the least. Given these findings, coupled with laboratory challenges in developing countries as well as ease of use on the field/cost effectiveness; we propose the simplified concentration as an optimal decontamination method for use in resource limited settings where TB remains an endemic problem.

Methods of sputum decontamination with emphasis on local tuberculosis laboratories.

One of the major goals for the global control of tuberculosis (TB) in humans is the laboratory diagnosis of Mycobacterium tuberculosis the causative agent of TB. This organism is present in sputum specimens which are often contaminated by other fast growing microflora. Therefore, the use of rapid and effective diagnostic methods for optimal detection of Mycobacterium tuberculosis is required through different decontamination methods. This review considers some of the decontamination methods that have been described for the recovery of M. tuberculosis based on published print and electronic articles. Some of these methods have limitations which may make them unsuitable for use in most local laboratories in the developing world; and these include unavailability of essential reagents and materials, cost of acquiring equipment, lack of skilled personnel and undue delay in the time of processing samples. Despite these challenges, there are some methods that have potentials of being adapted for use in clinical mycobacteriology laboratories in developing countries particularly Nigeria. With the correct laboratory logistics put in place, the simplified concentration, Kudoh-Kudoh, and modified Petroff methods may go a long way in achieving effective sputum decontaminations under local setting. The potentials and challenges of using other decontamination methods are discussed.

Seroprevalence of Brucella abortus and B. canis in household dogs in southwestern Nigeria: a preliminary report.

A preliminary serological study of 366 household dogs in Lagos and Ibadan, southwestern Nigeria, was carried out to determine antibodies due to exposure to Brucella abortus and B. canis, using the rose bengal test (RBT) and the rapid slide agglutination (RSA) test, respectively. Results showed that 5.46 % (20/366) and 0.27 % (1/366) of the dogs screened were seropositive to B. abortus and B. canis, respectively. Of all dogs, 36 had a history of being fed foetuses from cows and 11 (30.6 %) of these tested positive in the RBT. Our findings, although based on a limited sample size and a dearth of clinical details, revealed that dogs in Nigeria may be infected with Brucella spp. given the wide range of risk factors. Further studies are recommended to elucidate the epidemiology of brucellosis in dogs and its possible zoonotic consequences in the country.

Molecular epidemiology of human and animal tuberculosis in Ibadan, Southwestern Nigeria.

From 2005 to 2007, Mycobacterium tuberculosis complex (MTC) strains were isolated from cattle, goats and pigs samples collected at the Bodija abattoir and from human samples from tuberculosis patients and livestock traders at the Akinyele cattle market in Ibadan, Southwestern Nigeria. Seventy four isolates obtained from humans (24) and livestock (50) were identified as MTC strains. Thirty two isolates were spoligotyped. Nineteen of these 32 isolates were identified as M. tuberculosis whilst 13 were identified as Mycobacterium bovis. M. bovis was isolated from two humans, whereas M. tuberculosis was isolated from a bovine, a pig and a goat. All the M. bovis isolates identified in this study belonged to the Africa 1 clonal complex. Multiple locus VNTR [variable number of tandem repeats] analysis (MLVA) was carried out on the 74 isolates. Three major clusters were defined. Group A consisted of 24 M. tuberculosis isolates (MLVA genotypes 1-18). One strain was isolated from a bovine and one from a pig. Group B consisted of 49 M. bovis strains (MLVA genotypes 19-48), mainly of cattle origin but also included four goat, nine pig and two human isolates. Group C consisted of a single M. tuberculosis isolate (MLVA genotype 49) obtained from a goat. Spoligotyping and MLVA confirmed it as clustering with the East Africa Indian clade found in humans in Sudan and the Republic of Djibouti. The isolation of three M. tuberculosis strains from livestock raises the question of their epidemiological importance as a source of infection for humans.

Exploring the use of molecular epidemiology to track bovine tuberculosis in Nigeria: an overview from 2002 to 2004.

Tuberculosis remains a major public health problem in Nigeria. While human to human transmission of Mycobacterium tuberculosis is clearly of major importance in driving the tuberculosis epidemic in Nigeria, the impact of Mycobacterium bovis transmission from infected cattle is largely unknown. Molecular epidemiology of M. bovis in Nigeria will increase our understanding of this endemic disease and provide tools to assess cattle-to-human transmission. Between 2002 and 2004, molecular techniques including spoligotyping, variable number of tandem repeats (VNTR) typing and deletion typing were used to track and analyze a sample of strains of the M. tuberculosis complex circulating in the cattle population in Ibadan, Southwestern Nigeria. In all, 180 isolates were typed with a view to elucidating epidemiological information on circulating strains, occurrence of transborder transmission and molecular diversity of the M. bovis strains. Results obtained showed that 99% (178/180) of the isolates were M. bovis, while the remaining were M. tuberculosis and M. africanum. In all, strains of M. bovis had 34 different spoligotypes: strains with spoligotype pattern SB0944 (as designated by www.mbovis.org) were the most common (46% of strains). This molecular type is also common in countries neighbouring Nigeria. Strains with this spoligotype pattern could be further divided into 40 different VNTR types. This analysis shows the value of simple molecular epidemiological techniques applied to strains of M. bovis and suggests that further epidemiological studies will shed more light on the transmission dynamics of bovine tuberculosis locally and across neighbouring African countries.

Seroprevalence of bovine brucellosis in trade cattle slaughtered in Ibadan, Nigeria, from 2004-2006.

A seroprevalence study was carried out among trade cattle slaughtered at Bodija Municipal Abattoir, Ibadan (southwestern Nigeria) over a period of 3 consecutive years from 2004 to 2006 with a view to determining the breed, sex and age distribution in the seropositivity of bovine brucellosis. In total, 1642 animals were examined for antibodies to Brucella abortus using the Rose Bengal test. Seroprevalences of 6.00%, 6.17% and 5.31% were obtained in the years 2004, 2005 and 2006, respectively but a decrease in 2006 shows no significant difference (P > 0.05). The role of the breed (P > 0.05), sex (P > 0.05) and age (P > 0.05) in the occurrence of the infection was not statistically significant at 5%, although higher rates were obtained for females and older animals. The trend in the disease over the 3-year period showed that it is endemic in trade cattle slaughtered in Ibadan and the public health implications of this are discussed.

Using geographical information system to model the spread of tuberculosis in the University of Ibadan, Nigeria.

Nigeria currently ranks as the fourth highest burdened nation with tuberculosis (TB) globally; hence, new perspectives of addressing treatment and control of the disease are needed. New technology, such as Geographical Information Systems (GIS), may be useful in this process. We therefore sought to identify geographical areas where on-going TB transmission was occurring by linking GIS technology with disease surveillance in a University community in Ibadan, Nigeria. Retrospective data of TB incidence between 2004 and 2007 from the Health Centre in the University were cartographically mapped to show current trends in the spread of the disease and its geographic dispersion among those infected using ArcGIS 9.2 software and Global Positioning System (GPS). A total of 71 cases were detected over the study period. The mean age for the affected population was 27.76 +/- 8.46 (SD); fifty six (78.87%) patients being students while 15 (21.13%) were workers. The nearest neighbour distance analysis indicated a clustered pattern of locations; with zip code- 2 characterized by overcrowding and limited room space having increased likelihood of on-going transmission. This study therefore provides a preliminary synopsis of the uses of GIS in tuberculosis control in Nigeria; hence the need to explore it on a larger scale.