Dynamics of Mpox infection in Nigeria: a systematic review and meta-analysis

The seasonal outbreaks of Mpox continue in most parts of West and Central Africa. In the past year, Nigeria had the highest number of reported cases. Here, we used the PRISMA guidelines to carry out a systematic review and meta-analysis of available evidence on Mpox in Nigeria to assess the prevalence, transmission pattern, diagnostic approach, and other associated factors useful for mitigating the transmission of the disease. All relevant observational studies in PubMed/MEDLINE, Embase, AJOL, Web of Science, Scopus and Google Scholar on Mpox in Nigeria were assessed within the last fifty years (1972 to 2022). In all, 92 relevant articles were retrieved, out of which 23 were included in the final qualitative analysis. Notably, most of the cases of Mpox in Nigeria were from the southern part of the country. Our findings showed a progressive spread from the southern to the northern region of the country. We identified the following factors as important in the transmission of Mpox in Nigeria; poverty, lack of basic healthcare facilities, and risk of exposure through unsafe sexual practices. Our findings reiterate the need to strengthen and expand existing efforts as well as establish robust multi-sectoral collaboration to understand the dynamics of Mpox Nigeria.

Ecological correlates and predictors of Lassa fever incidence in Ondo State, Nigeria 2017-2021: an emerging urban trend

Lassa fever (LF) is prevalent in many West African countries, including Nigeria. Efforts to combat LF have primarily focused on rural areas where interactions between rodents and humans are common. However, recent studies indicate a shift in its occurrence from rural to urban areas. We analysed secondary data of reported LF outbreaks from 2017 to 2021 in Ondo State, Nigeria to identify the distribution pattern, ecological variations, and other determinants of disease spread from the ward level using nearest neighbour statistics and regression analysis. Data utilised include LF incidence, ecological variables involving population, nighttime light intensity, vegetation, temperature, market presence, road length, and building area coverage. ArcGIS Pro 3.0 software was employed for spatial analysis. Results revealed spatio-temporal clustering of LF incidents between 2017 and 2021, with an increasing trend followed by a decline in 2021. All wards in Owo Local Government Area were identified as LF hotspots. The ecological variables exhibited significant correlations with the number of LF cases in the wards, except for maximum temperature. Notably, these variables varied significantly between wards with confirmed LF and those without. Therefore, it is important to prioritise strategies for mitigating LF outbreaks in urban areas of Nigeria and other LF-endemic countries.

If You're Not Confused, You're Not Paying Attention: Ochrobactrum Is Not Brucella

Bacteria of the genus Brucella are facultative intracellular parasites that cause brucellosis, a severe animal and human disease. Recently, a group of taxonomists merged the brucellae with the primarily free-living, phylogenetically related Ochrobactrum spp. in the genus Brucella. This change, founded only on global genomic analysis and the fortuitous isolation of some opportunistic Ochrobactrum spp. from medically compromised patients, has been automatically included in culture collections and databases. We argue that clinical and environmental microbiologists should not accept this nomenclature, and we advise against its use because (i) it was presented without in-depth phylogenetic analyses and did not consider alternative taxonomic solutions; (ii) it was launched without the input of experts in brucellosis or Ochrobactrum; (iii) it applies a non-consensus genus concept that disregards taxonomically relevant differences in structure, physiology, population structure, core-pangenome assemblies, genome structure, genomic traits, clinical features, treatment, prevention, diagnosis, genus description rules, and, above all, pathogenicity; and (iv) placing these two bacterial groups in the same genus creates risks for veterinarians, medical doctors, clinical laboratories, health authorities, and legislators who deal with brucellosis, a disease that is particularly relevant in low- and middle-income countries. Based on all this information, we urge microbiologists, bacterial collections, genomic databases, journals, and public health boards to keep the Brucella and Ochrobactrum genera separate to avoid further bewilderment and harm.

Phenotypic Characterization and Antibiograms of Extended-Spectrum Beta-Lactamase-Producing Escherichia coli Isolated at the Human-Animal-Environment Interface Using a One Health Approach Among Households in Wakiso District, Uganda

Background

The occurrence of extended spectrum beta-lactamase (ESBL) producing bacteria such as Escherichia coli has increasingly become recognized beyond hospital settings. Resistance to other types of antibiotics limits treatment options while the existence of such bacteria among humans, animals, and the environment is suggestive of potential zoonotic and reverse-zoonotic transmission. This study aimed to establish the antibiotic susceptibility profiles of the ESBL-producing Escherichia coli (ESBL-EC) from human, animal, and environmental isolates obtained among farming households within Wakiso district using a One Health approach.

Methods

A total of 100 ESBL-EC isolates from humans 35/100 (35%), animals 56/100 (56%), and the environment 9/100 (9%) were tested for susceptibility to 11 antibiotics. This was done using the Kirby-Bauer disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Data were analyzed in STATA ver. 16 and graphs were drawn in Microsoft excel ver. 10.

Results

Most of the ESBL-EC isolates (98%) were resistant to more than two antibiotics. ESBL-EC isolates were most susceptible to meropenem (MEM) (88.0%), and imipenem (82.0%) followed by gentamicin (72%). ESBL-EC isolates from humans were most susceptible to meropenem (MEM) followed by imipenem (IPM)> gentamicin (CN)> ciprofloxacin (CIP). Animal samples were more susceptible to MEM, IPM, and CN but were highly resistant to cefotaxime (CTX)> cefepime (FEP)>other antibiotics. Multidrug resistance (MDR) was mostly reported among households keeping goats under intensive husbandry practices. Seven percent of the isolates exhibited carbapenem resistance while 22% showed aminoglycoside resistance. Similar resistance patterns among humans, animals, and environmental samples were also reported.

Conclusion

Our study provides baseline information on non-hospital-based MDR caused by ESBL-EC using a One Health approach. ESBL-EC isolates were prevalent among apparently healthy community members, animals, and their environment. It is important to conduct more One Health approach studies to generate evidence on the drivers, resistance patterns, and transmission of ESBL-producing organisms at the human-animal-environmental interface.

Seroprevalence of brucellosis and Q fever infections amongst pastoralists and their cattle herds in Sokoto State, Nigeria

Brucellosis and Q fever are neglected zoonoses of global health importance, with unknown true prevalence in occupationally vulnerable settings, partly due to misdiagnosis for other febrile conditions and poor access to primary health care. We examined the seroprevalence of these diseases and associated factors amongst pastoralists and their cattle in Sokoto State, a hub of cattle and pastoral populations in Nigeria. Serum samples randomly collected from 137 pastoralists and 366 cattle from 27 herds in three selected Local Government Areas (LGAs) in the state were analysed for antibodies to Brucella abortus using Rose Bengal Plate Test (RBT) and competitive Enzyme-Linked Immunosorbent Assay (cELISA) as well as antibodies to Coxiella burnetti using indirect ELISA. Consenting pastoralists' knowledge, perception and practices about the diseases were assessed using a semi-structured questionnaire. Data were analysed using descriptive statistics and bivariate analysis at p ≤ 0.05 level of significance. Brucellosis adjusted individual seroprevalence were 0.83% (95%CI: 0.04-4.59%) and 0% among pastoralists; 2.28% (95%CI: 1.16-4.43%) and 5.70% (95%CI: 3.68-8.74%) in cattle by RBT and cELISA, respectively. Adjusted herd-level seroprevalence for brucellosis were 23.20% (95%CI: 11.07-42.54%) and 42.00% (95%CI: 25.27-61.11%) by RBT and cELISA, respectively. For Q fever, higher seroprevalence of 62.57% (95%CI: 54.04-70.46%) and 2.98% (95%CI: 1.57-5.58%) were recorded amongst the pastoralists and their cattle, respectively. with adjusted herd-level seroprevalence of 40.36% (95%CI: 22.57-63.17%). The LGAs of sampling were significantly (OR: 0.2; 95%CI: 0.02-1.00) associated with Q fever infection, though marginal. The majority of the pastoralists had poor knowledge, perception and practices towards the diseases. This is the first study establishing the presence of brucellosis and Q fever at the human-animal interface in Sokoto State, Nigeria. The pastoralists' poor knowledge, perception and practices about these diseases are worrisome and are important factors for consideration in disease control.

Ethical issues in the COVID-19 pandemic control preparedness in a developing economy

Adequate preparation for highly pathogenic infectious disease pandemic can reduce the incidence, prevalence and burden of diseases like COVID-19 pandemic. An antidote to the spread of the disease is adequate preparation for its control since there is no proven curative measure yet. Effective management of identified cases, social distancing, contact tracing and provision of basic infrastructure to facilitate compliance with preventive measures, testing are proven management strategies. Although these measures seem to be the best options presently, it is important to pay attention to ethical issues arising from the implementation process to ensure best practice. While disease epidemic is not alien to human societies, lessons from previous outbreaks are vital for addressing future outbreaks. For effective control of this pandemic, there should be a clear definition of social distancing in terms of distance and space in line with the WHO definition, adequate provision of basic amenities, screening and testing with specific criteria for selecting those to be screened. Also, there should be a free testing procedure, access to treatment opportunities for those who test positive, ethical free contact tracing practice, respect for the autonomy of those to be tested, and global best practice of open science, open data and data sharing practices. In conclusion, a framework/guideline for epidemic/pandemic ethics guidance should be developed while an ethical sensitive communication manual should be prepared for public engagement on epidemic and pandemic.

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.

Tuberculosis in Liberia: high multidrug-resistance burden, transmission and diversity modelled by multiple importation events

Tuberculosis (TB) surveillance is scarce in most African countries, even though it is the continent with the greatest disease incidence according to the World Health Organization. Liberia is within the 30 countries with the highest TB burden, probably as a consequence of the long civil war and the recent Ebola outbreak, both crippling the health system and depreciating the TB prevention and control programmes. Due to difficulties working in the country, there is a lack of resistance surveys and bacillus characterization. Here, we use genome sequencing of Mycobacteriumtuberculosis clinical isolates to fill this gap. Our results highlight that the bacillus population structure is dominated by lineage 4 strains that harbour an outstanding genetic diversity, higher than in the rest of Africa as a whole. Coalescent analyses demonstrate that strains currently circulating in Liberia were introduced several times beginning in the early year 600 CE until very recently coinciding with migratory movements associated with the civil war and Ebola epidemics. A higher multidrug-resistant (MDR)-TB frequency (23.5 %) than current estimates was obtained together with non-catalogued drug-resistance mutations. Additionally, 39 % of strains were in genomic clusters revealing that ongoing transmission is a major contribution to the TB burden in the country. Our report emphasizes the importance of TB surveillance and control in African countries where bacillus diversity, MDR-TB prevalence and transmission are coalescing to jeopardize TB control programmes.

Control of paratuberculosis: who, why and how. A review of 48 countries

Paratuberculosis, a chronic disease affecting ruminant livestock, is caused by Mycobacterium avium subsp. paratuberculosis (MAP). It has direct and indirect economic costs, impacts animal welfare and arouses public health concerns. In a survey of 48 countries we found paratuberculosis to be very common in livestock. In about half the countries more than 20% of herds and flocks were infected with MAP. Most countries had large ruminant populations (millions), several types of farmed ruminants, multiple husbandry systems and tens of thousands of individual farms, creating challenges for disease control. In addition, numerous species of free-living wildlife were infected. Paratuberculosis was notifiable in most countries, but formal control programs were present in only 22 countries. Generally, these were the more highly developed countries with advanced veterinary services. Of the countries without a formal control program for paratuberculosis, 76% were in South and Central America, Asia and Africa while 20% were in Europe. Control programs were justified most commonly on animal health grounds, but protecting market access and public health were other factors. Prevalence reduction was the major objective in most countries, but Norway and Sweden aimed to eradicate the disease, so surveillance and response were their major objectives. Government funding was involved in about two thirds of countries, but operations tended to be funded by farmers and their organizations and not by government alone. The majority of countries (60%) had voluntary control programs. Generally, programs were supported by incentives for joining, financial compensation and/or penalties for non-participation. Performance indicators, structure, leadership, practices and tools used in control programs are also presented. Securing funding for long-term control activities was a widespread problem. Control programs were reported to be successful in 16 (73%) of the 22 countries. Recommendations are made for future control programs, including a primary goal of establishing an international code for paratuberculosis, leading to universal acknowledgment of the principles and methods of control in relation to endemic and transboundary disease. An holistic approach across all ruminant livestock industries and long-term commitment is required for control of paratuberculosis.

Neutralizing antibodies against Simbu serogroup viruses in cattle and sheep, Nigeria, 2012-2014

Background

Simbu serogroup viruses of the Orthobunyavirus genus (Family Peribunyaviridae) include teratogenic pathogens that cause severe economic losses, abortions, stillbirths and congenital abnormalities in ruminants worldwide. Although they were initially isolated from ruminants and Culicoides biting midges about five decades ago in Nigeria, there is no current information on their prevalence and geographical distribution despite reports of abortions and congenital malformations in the country’s ruminant population. Here, apparently healthy cattle and sheep obtained from eight states in the three major vegetation zones of Nigeria were screened for the presence of specific neutralizing antibodies against Schmallenberg virus (SBV), Simbu virus (SIMV) and Shamonda virus (SHAV).

Results

Using a cross-sectional design, 490 cattle and 165 sheep sera were collected between 2012 and 2014 and tested by a commercial SBV ELISA kit which enables the detection of antibodies against various Simbu serogroup viruses. The seropositivity rates for cattle and sheep were 91.2% and 65.4%, respectively. In cattle, there was no association between ELISA seropositivity and vegetation zone. However, the prevalence of anti-Simbu serogroup antibodies was significantly higher in Ebonyi State compared to other states in the rainforest vegetation zone. The seroprevalence was significantly higher in sheep obtained from live animal markets compared to farms (OR = 5.8). Testing of 20 selected ELISA-positive sera by serum neutralisation test showed that all were positive for one or more of SBV, SIMV and SHAV with the highest titres obtained for SHAV. Antibodies to SBV or a closely related virus were detected in the Sudan savannah and rainforest zones, anti-SIMV antibodies were detected only in the rainforest zone, while anti-SHAV antibodies were found in the three vegetation zones.

Conclusion

The findings of this study reveal that following the early isolation of Simbu serogroup viruses in Nigeria in the 1960s, members of this virus group are still circulating in the country. Specifically, SBV, SIMV and SHAV or closely related viruses infect cattle and sheep across the three vegetation zones of Nigeria suggesting that insect vector activity is extensive in the country. The exact vegetation zone where the animals became exposed to the viruses could, however, not be determined in this study.

SEROLOGICAL SURVEY OF TOXOPLASMOSIS, NEOSPOROSIS AND BRUCELLOSIS AMONG CATTLE HERDS IN OYO STATE, SOUTH-WESTERN NIGERIA

BACKGROUND

Several zoonotic diseases are known to constitute great impediment to livestock management and production worldwide, especially in developing countries where control measures are largely non-existent. This study sets out to investigate the occurrence of toxoplasmosis, neosporosis and brucellosis among cattle herds in Oyo State, southwest Nigeria.

MATERIALS AND METHODS

A cross-sectional survey to screen for antibodies to Toxoplasma gondii, Neospora caninum and Brucella abortus was conducted among 174 cattle in 17 herds. Sera obtained from the cattle were screened for antibodies to Toxoplasma gondii and Neospora caninum using enzyme-linked immunosorbent assay (ELISA) and for Brucella abortus antibodies using Rose Bengal test and Competitive Enzyme Linked Immunosorbent Assay (cELISA).

RESULTS

Overall, herd level prevalence of 52.9%, 23.5% and 23.5% as well as individual prevalence of 7.5%, 3.4% and 3.4% was obtained for toxoplasmosis, neosporosis and brucellosis, respectively. Antibodies to T. gondii, N. caninum and B. abortus were detected in 2 of the 17 herds, T. gondii and N. caninum in 4 herds, and T. gondii and B. abortus in 4 herds. Statistically significant association was only found between seropositivity to T. gondii antibodies and sex (p<0.05).

CONCLUSION

Our results showed that toxoplasmosis, neosporosis and brucellosis are prevalent among cattle herds screened in the study area. Considering the potential impact of these diseases on livestock management and production, extensive surveillance is necessary for development and implementation of effective control and prevention strategies.

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.

Bovine tuberculosis: a retrospective study at Jos abattoir, Plateau State, Nigeria

Introduction

Nigeria has the thirteenth highest burden of human tuberculosis. The current increasing incidence of tuberculosis in humans, particularly in immune-compromised persons, has given interest in the zoonotic importance of Mycobacterium bovis in developing countries like Nigeria. This study determined the prevalence of bovine tuberculosis as a background information for effective control measures in Plateau State in cattle population.

Methods

We reviewed surveillance records on cattle slaughtered and suggestive tuberculosis lesions from cattle slaughtered annually from 2007-2012 in Jos abattoir, Plateau State. Bovine tuberculosis cases at post mortem were based on examination of characteristics TB lesion on organs by Veterinary officers. We performed descriptive analysis using Epi info version 3.5.3 and Microsoft Excel 2007.

Results

A total of 52, 262 cattle were slaughtered from 2007-2012, out of which 4, 658 (11.2%) had evidence of tuberculosis lesion at post mortem. The average yearly prevalence was 9.1% but varied from a high of 16.3% in 2007 to a low of 3.1% in 2012. Trend analysis showed that bovine tuberculosis had a seasonal variation and peaked mostly in July and August. The number of suggestive Tb lesion cases was highest in the month of August and lowest in the month of January, 2007-2012.

Conclusion

This study shows that bovine tuberculosis is endemic in Plateau State. Trend analysis showed that bovine tuberculosis is seasonal and peaked mostly in July and August. Continuous surveillance through meat inspection is required to prevent zoonotic transmission of bovine tuberculosis.

Prevalence and risk factors of Mycobacterium tuberculosis complex infection in slaughtered cattle at Jos South Abattoir, Plateau State, Nigeria

INTRODUCTION

Bovine tuberculosis (BTB) is widespread yet poorly controlled in Nigeria hence posing a public health threat. This study determined the prevalence of Mycobacterium tuberculosis complex (MTC) and factors associated with MTC among slaughtered cattle at Jos South Abattoir in Plateau State, Nigeria.

METHODS

We conducted a cross sectional study in which we collected 168 lung samples systematically from 485 slaughtered cattle from May-June, 2012, and tested for acid fast bacilli (AFB) using Ziehl-Neelsen test and a duplex polymerase chain reaction technique (PCR) for MTC detection. Data on cattle socio-demographic characteristics and risk factors for zoonotic BTB infection was obtained and analyzed using Epi info version 3.5.3 to determine frequency, proportions, and prevalence odds ratios. Multiple logistic regression was done at 95% Confidence Interval (CI).

RESULTS

The mean age of the cattle was 5.6 ± 1.3 years and (108) 64.3% were females. Majority were indigenous White Fulani breed of cattle (58.5%) and about half (54.8%) were slightly emaciated. Prevalence of MTB complex was 21.4% by AFB test and 16.7% by duplex PCR. Of 33 (19.6%) lungs with lesions, 27 (81.8%) were positive for AFB; while of 135 (80.4%) lungs without lesions, 9 (6.7%) were positive for AFB. Lungs with lesions were 52 times more likely to test positive to AFB test compared to tissues without lesions (AOR=52.3; 95% CI: 16.4-191.8).

CONCLUSION

The presence of MTC in cattle signifies its potential risk to public health. Presence of lesions on lungs is a reliable indicator of MTC infection that meat inspectors should look out for.

Factors associated with tuberculosis among patients attending a treatment centre in Zaria, North-west Nigeria, 2010

Introduction

Tuberculosis remains a global public health problem. In 2011, tuberculosis incidence was 133 per 100,000 in Nigeria. In Nigeria, little is known about the factors associated with tuberculosis, especially in the northern part and only few studies have characterized the Mycobacterium species that cause tuberculosis infection in humans. This study determined factors associated with tuberculosis and identified Mycobacterium species causing human tuberculosis in North-West, Nigeria.

Methods

We conducted a hospital based case control study between April and July 2010 in Zaria. Cases were newly diagnosed sputum smear-positive tuberculosis patients >15 years while controls were patients >15 years attending the hospital for other reasons but were negative for tuber-culosis. We used a structured questionnaire to obtain information on demographics, knowledge of transmission of tuberculosis, and exposure to some factors. We preformed descriptive, bivariate and backward elimination logistic regression. Sputa from cases were analyzed by multiplex polymerase chain reaction (PCR) based on genomic regions of difference.

Results

The mean ages of the cases and controls were 36, standard deviation (SD) 9.0 and 36, SD 9.7 respectively. Only 10 (9.8%) and nine (8.8%) of cases and controls respectively had a good knowledge of the transmission of tuberculosis. Contact with a tuberculosis patient (adjusted odds ratio (AOR) 12.3, 95% confidence interval (CI) 5.2-28.8), consumption of unpasteurized milk (AOR 6.4, CI 2.4-17.2), keeping pets (AOR 5.6, CI 2.3-13.7), associating closely with cattle (AOR 5.6, CI 1.3-6.8), and overcrowding (AOR 4.8, CI 1.8-13.1) were significantly associated with tuberculosis. Of the 102 sputa analyzed, 91 (89%) were M. tuberculosis, 8 (7.8%) were M africanum.

Conclusion

We identified possible opportunities for intervention to limit the spread of tuberculosis. We recommend that the Nigeria tuberculosis control program consider some of these factors as a way to mitigate the spread of tuberculosis in Nigeria.

African 2, a clonal complex of Mycobacterium bovis epidemiologically important in East Africa

We have identified a clonal complex of Mycobacterium bovis isolated at high frequency from cattle in Uganda, Burundi, Tanzania, and Ethiopia. We have named this related group of M. bovis strains the African 2 (Af2) clonal complex of M. bovis. Af2 strains are defined by a specific chromosomal deletion (RDAf2) and can be identified by the absence of spacers 3 to 7 in their spoligotype patterns. Deletion analysis of M. bovis isolates from Algeria, Mali, Chad, Nigeria, Cameroon, South Africa, and Mozambique did not identify any strains of the Af2 clonal complex, suggesting that this clonal complex of M. bovis is localized in East Africa. The specific spoligotype pattern of the Af2 clonal complex was rarely identified among isolates from outside Africa, and the few isolates that were found and tested were intact at the RDAf2 locus. We conclude that the Af2 clonal complex is localized to cattle in East Africa. We found that strains of the Af2 clonal complex of M. bovis have, in general, four or more copies of the insertion sequence IS6110, in contrast to the majority of M. bovis strains isolated from cattle, which are thought to carry only one or a few copies.

Molecular analysis of human and bovine tubercle bacilli from a local setting in Nigeria

To establish a molecular epidemiological baseline for the strains causing tuberculosis in Nigeria, a survey of isolates from humans and cattle was carried out. Spoligotyping and variable-number tandem-repeat analysis revealed that the majority of tuberculosis disease in humans in Ibadan, southwestern Nigeria, is caused by a single, closely related group of Mycobacterium tuberculosis strains. Using deletion typing, we show that approximately 13% of the disease in humans in this sample was caused by strains of Mycobacterium africanum and Mycobacterium bovis rather than M. tuberculosis. Molecular analysis of strains of M. bovis recovered from Nigerian cattle show that they form a group of closely related strains that show similarity to strains from neighboring Cameroon. Surprisingly, the strains of M. bovis recovered from humans do not match the molecular type of the cattle strains, and possible reasons for this are discussed. This is the first molecular analysis of M. tuberculosis complex strains circulating among humans and cattle in Nigeria, the results of which have significant implications for disease control.