Efforts to reduce the
tuberculosis burden, therefore, must include strategies to reduce
incidence of the bacteria in animals using "One Health" approach.
‘A disease modeling approach has been used to analyze the cost and effectiveness of interventions aimed at bovine tuberculosis among cattle in Morocco.’
Researchers reporting in PLOS Neglected Tropical Diseases
used a disease modeling approach to analyze the cost and effectiveness
of interventions aimed at bovine tuberculosis among cattle in Morocco.
Around 18% of cattle in Morocco carry Mycobacterim bovis
which can cause tuberculosis in humans who catch the bacteria from
consuming raw milk or being in contact with infected animals. One
previous study found that 17.8% of drug resistant TB among humans in
Morocco was due to M. bovis
rather than the classic
Mycobacterium tuberculosis. The main strategy to control bovine
tuberculosis (BTB) in Morocco is based on a test and slaughter scheme,
but testing is not mandatory.
In the new work, Jakob Zinsstag and Nakul Chitnis, of the Swiss
Tropical and Public Health Institute, associated with the University of
Basel and their colleagues, in partnership with the Institut Agronomique
et Vétérinaire, Hassan II, Rabat, Morocco, developed a mathematical
model of BTB transmission from cattle to cattle and cattle to humans in
order to assess the disease cost and simulate interventions. They
assumed a prevalence of 18% among cattle and used annual data on cattle
numbers collected by the Moroccan Ministry of Agriculture.
The time until less than one in a thousand cattle are newly infected
with BTB in Morocco depends on the proportion of testing. The model
showed that the time to bovine tuberculosis elimination ranged from 12
years - with a 100% tested - to 75 years - when only 20% of cattle were tested annually.
Assuming testing rates were
higher than 40%, costs for the program ranged from 1.47 to 1.6
billion Euros and led to freedom from disease in 12 to 32 years. The
simulation also suggested that using a more conservative cutoff for a
positive skin test for BTB would result in cheaper and quicker
elimination of the disease. Further studies are needed, however, to
better describe the prevalence of BTB in humans in Morocco.
"The economic assessment presented here is preliminary, and a
detailed cost and cost-effectiveness analysis will be published
separately," the researchers say. "However, our analysis informs
Moroccan bovine tuberculosis control policy on the time horizon, range
of cost and optimal levels of intervention. An effective control program
will depend on the human resources and technical and logistical
capacity of the veterinary services to implement testing and
slaughtering of animals."