Bovine Tuberculosis in Rwanda: Prevalence and Economic

Impact Evaluation by Meat Inspection at Société d’Abattoir

de Nyabugogo-Nyabugogo Abattoir, Kigali

Gervais Habarugira*1, Joseph Rukelibuga2, Mark Nanyingi3, 5

Borden Mushonga4

1School of Animal Sciences and Veterinary Medicine, College of Agriculture, Animal Sciences and Veterinary Sciences, University of Rwanda, Nyagatare, Rwanda.

2US-Centre for Disease Control and Prevention (CDC), Kigali, Rwanda.3Department of Public Health, Pharmacology and Toxicology, University of Nairobi Nairobi, Kenya.

4Department of Livestock and Pasture Science, Faculty of Science and Agriculture, University of Fort Hare, South Africa.

5Kenya Medical Research Institute, United States Centres for Disease Control and Prevention, Kenya

Corresponding Author: Gervais Habarugira gervaish@gmail.com*

Presented at the Inaugural Regional conference on Zoonotic Diseases in Eastern

Africa, Naivasha, Kenya on Tuesday, March 10th, 2015

Etiology: TB in humans is primarily caused by

Mycobacterium tuberculosis (M. tb), it represents

the greatest burden of infectious diseases second

to AIDS worldwide.

Global incidence estimates : 8.7 million cases

of & 1.4 million deaths/3,833 daily (WHO 2011)

Burden: 17 million Disability Adjusted Life Years (DALY), social impact underestimated.

Drug resistance: 480,000 people with MDR-TB

Rwanda prevalence estimates: human TB due

to (M. tb) 0.08% in 2008 (MOH 2008).

INTRODUCTION: GLOBAL ZOONOTIC TB BURDEN

(WHO Annual TB report, 2011, WHO TB Factsheet 2014)

Pathogen host and species jump : Cattle is the

main host of Mycobacterium bovis (M. bovis) and

leads to latent infection in immunocompromised

humans (LTBI)(Gortázar et al. 2008, Cicero et al. 2009)

Global Burden: >128 countries reported M. bovis clinical disease in cattle population, ≈ 50 million

cattle at risk globally (Michel et al. 2002, Chantal 2001).

Transmission: Consumption of infected animal

products (milk) or inhalation of droplets.

Zoonotic Challenges: Human-livestock-wildlife

interactions, HIV, high prevalence of b TB,

Pasteurization failures of milk, drug resistance

(PZA)

ZOONOTIC POTENTIAL OF MYCOBACTERIUM BOVIS

(CDC TB Factsheet, Cosivi et al.1998)

To determine the prevalence of bTB by evaluating the presence of

granulomatous lesions in cattle at SABAN Abattoir, Kigali

To identify different mycobacteria species that are responsible for

lesions resembling tuberculosis

Evaluate the economic impact of bTB to the beef industry in

Rwanda.

RESEARCH QUESTION

Lack of surveillance and Diagnosis in Rwanda : Underreporting and

underestimation of human TB caused by M. bovis.

Lack of Prevalence data: on national-wide bovine tuberculosis in

cattle, All forms of human TB estimated at 91.3/10,000 pop/yr.

RESEARCH OBJECTIVES

MATERIALS AND METHODS

Geographical Study Area: The study was carried out at SABAN-Nyabugogo abattoir in Kigali

on slaughtered animals from four Provinces (East, North, South and West) and Kigali city

(Jan-Nov 2009)

Cross-sectional design: A stratified cluster sampling proportional to the size of the cattle

population

STUDY DESIGN : PATHOLOGY & LAB ANALYSIS

Lab analysis: Microbiological laboratory of Higher Institute of Agriculture and Animal

Husbandry (ISAE)

RESULTS: PATHOLOGICAL TUBERCULOUS LESIONS

ORGAN CONDEMNED COUNT PERCENTAGE (%)

Head 65 43.9

Lungs 19 12.8

Liver 50 33.8

Intestine 8 5.4

Kidney 2 1.3

Abomasum 1 0.6

Whole carcass 3 2.0

Total 148 100

Overall prevalence of gross tuberculous lesions = 0.9%

RESULTS: PATHOLOGICAL TUBERCULOUS LESIONS

Liver and Mediastinal Lymphnodes with caseous necrotic tubercles

The overall postmortem prevalence of M. bovis using culture was

estimated to be 0.5% (0.587*148/16753)

RESULTS:PREVALENCE OF BTB ACCORDING TO SEX

Slaughtered cattle

according to sex

Count Organ condemned Occurrence

(%)

Males 10 051 61 0.6

Females 6 702 87 1.4

Total 16 753 148 1.9

Females higher prevalence attributed to: (p < 0.05, n = 16 753) Husbandry stress caused by poor housing and extended confinement

Higher vulnerability to infection due Lactation and gestation.

Prolonged contact with humans infected with TB during milking (Imtiaz et

al. 2008; Skuce, Allen & McDowell 2011).

RESULTS:PREVALENCE OF BTB ACCORDING TO AGE

Age differentials and prevalence attributed to:

Prolonged overall exposure increases exponentially with age.

Possibility of vertical transmission of infection(in-utero)

The macroscopic lesions appear at advanced stages of infection

(Awah-Ndukum et al.2012)

Slaughtered cattle

according to age

Number Organ condemned Occurrence

(%)

Less than 2 years 11 966 72 0.6

Over 2 years 4 787 76 1.6

Total 16 753 148 0.9

Prevalence of test positives increased significantly with cattle age (p<0.001)

LABORATORY FINDINGS: MICROSCOPY

Cultures

(-)

Cultures

(+)

Total Percentage

(%)

Kinyoun(-) 8 2 10 27.8

Kinyoun(+) 5 21 26 72.2

Total 13 23 36 100

Percentage(%) 36.1 63.9 100 -

The overall postmortem prevalence of M. bovis using culture was estimated to be

0.5% (0.587*148/16753)

36 samples microscopically examined, 26 (72.2%) were positive to Kinyoun staining.

LABORATORY FINDINGS: BACTERIOLOGY

Condemned

organ

Positives

Cultures

Positive Results

Mycobacterium

bovis

Results for

atypical

mycobacteria

Number Percent

(%)

Number Percent

(%)

Lymphnodes 19 17 89.5 2 10.5

Lung 2 2 100 0 0

Liver 2 2 100 0 0

Total 23 21 91.3 2 8.7

Mycobacterium bovis was present in 91.3% (n=36) of the samples vs. 8.7% (n=36) for atypical mycobacteria

ECONOMIC AND PUBLIC HEALTH IMAPCTS

A total of 1 683.5 kg of meat was condemned and the loss was

estimated to 3 030 300Frw (USD 4810) based on the prevailing

meat market prices.

Malnutrition: RDAI (6g of animal protein) translates into loss of

animal proteins for 345 persons per year.

Value chain impacts: Decreases livestock productivity may be

economically devastating for the dairy sector. Milk yields and draft

power can be significantly reduced, with direct effects on the

livelihoods of poor livestock holders (WAHID 2012)

Public health impacts at crossroads with opportunistic HIV/AIDS

infections.

The prevalence of bTB in Rwanda is significant and requires continued

implementation of surveillance and control measures.

Routine meat inspection protocols utilised in Rwandan abattoirs are able to detect

0.9% of bTB lesions at the gross level.

A comparative sensitivity of tests: The sensitivity of Kinyoun staining compared to

culture was 91.3%, while the specificity was 61.5%.

The molecular and epidemiological analysis of the M. bovis in Rwanda is necessary

to determine the clonal lineages from different provinces.

Risk factor analysis for comparing with prevalence of cattle interdermal test positives

of cases.

Studies are needed to assess the risk of zoonotic TB among populations in regions

where socio-cultural and economic factors increase the risk posed by this zoonosis.

DISCUSSION AND CONCLUSION

Habarugira et al., 2014

Evaluation of Molecular diagnostics: Polymerase chain reaction for higher

sensisitivity and specificity of bTb genetic diversity detection.

Molecular epidemiology: Determination of the Rwanda population structure and

description of the epidemiological units?

The spoligotypes naming according to the M. bovis Spoligotype Database website

(www.mbovis.org ).

1. Ministry of Health 2009, Annual Report 2009

2. Cosivi O et al., 1998, Zoonotic tuberculosis due to Mycobacterium

bovis in developing countries. Emerging Infectious Diseases 4: 59-70

3. Gortázar C et al., 2008 : The Role of Wild Ungulates as Disease

Reservoirs in the Last Iberian Lynx Strongholds. PLoS ONE

4. Michel, A.L., 2002, ‘Implications of tuberculosis in African wildlife and

livestock’, Annals of the New York Academy of Sciences.

5. OIE, 2009, Manual of diagnostic tests and vaccines for terrestrial

animals: Bovine tuberculosis.

REFERENCES(SELECTED)

University of Rwanda for providing funding for the research

Dr. Anselme Achille Shyaka through his unconditional support, we

were able to overcome the difficult times that we had during this

study.

Dr. Louis Fischer for his advice and support, both materially and

morally.

Technicians of Saban Nyabugogo abattoir and laboratories of ISAE

Busogo who assisted respectively in samples collection and

laboratory analysis.

The organizers of RCZEA and Audience for Kind Attention!

ACKNOWLEDGEMENTS