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.

Prevalence of previously undetected tuberculosis and underlying risk factors for transmission in a prison setting in Ibadan, south-western Nigeria

People with congregational tendencies such as the prison inmates constitute an important target group in the global efforts towards the control of tuberculosis (TB). The prison setting in most developing countries particularly Nigeria, currently does not have routine diagnostic procedures for TB despite the existing risks that could facilitate disease transmission. We conducted a cross sectional study among the inmates in a major prison in south-western Nigeria for TB by screening their sputum samples using a simple random sampling method coupled with questionnaire interview, on the assumption of sub-clinical pulmonary TB infection. The overall TB prevalence found was 1.2% (2/164). Significant risk factors that could facilitate disease transmission in the prison included lack of BCG immunization (p = 0.017); history of contact with TB patients (p = 0.020); prolonged cough (p = 0.016) and drug abuse (p = 0.019). Our findings of 1.2% undetected pulmonary TB infection among the inmates though low; still reiterate previous observation that the prison setting constitutes a veritable environment for TB transmission and a threat to public health. Efforts are therefore needed to institute routine screening and reduce the risk factors associated with TB transmission among prison inmates in Nigeria.

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.

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.

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.

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.

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.

Mycobacterium fortuitum from lesions of slaughtered pigs in Ibadan, Nigeria

To ascertain the cause of tuberculous-like lesions in pigs slaughtered in a local abattoir in Ibadan (south-western Nigeria), a total of 516 pigs were inspected over a period of four months, 18 of which had gross lesions suggestive of tuberculosis at post-mortem. Mycobacterial culture and molecular typing (GenoType Mycobacterium CM [Common Mycobacteria] assay) analysis were used to identify and confirm the mycobacteria species responsible for these lesions. Results show that 2.3% (12/516) of the animals screened were infected with mycobacteria; Mycobacterium fortuitum was confirmed in 33.3% (4/12) of these cases. As far as the authors are aware, this is the first report confirming the isolation of M. fortuitum in slaughtered pigs in Nigeria. There is a need to improve on necessary preventive and control measures that will reduce potential sources of mycobacterial infections in pig-rearing herds. These infections may also have public health implications, especially to workers in the pig industry.

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.

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.

The use of the milk ring test and rose bengal test in brucellosis control and eradication in Nigeria

In this study, milk and blood samples collected simultaneously from 532 trade cows to be slaughtered at Bodija abattoir, Ibadan (southwestern, Nigeria) were examined for antibodies to Brucella using the milk ring test (MRT) and the rose bengal test (RBT). Overall, 18.61% of the milk samples were positive according to the MRT, while 9.77% of the serum samples were positive according to the RBT. The difference was highly significant (Chi-square value 16.33; P < 0.05); only 32 (6.02%) of the samples were positive for both tests. The Red Bororo breed of cattle and the White Fulani had the highest positive rates, namely 20.93% and 11.69% for the MRT and RBT respectively. No conclusion can be drawn about sensitivity because we do not know the true status of the animals tested. It is, however, obvious that although the MRT and RBT are 1st-line screening tests for brucellosis in cows in some countries, their lack of specificity is of concern. Therefore, the requirement for other confirmatory tests that are more specific should be considered for control and eradication of the disease, especially in Nigeria.