Economics of Bovine Tuberculosis: A One Health Issue 33
The public health burden of zoonotic TB in
industrialized countries is low because of the
pasteurization of milk and/or its effective elimi-
nation in cattle. Rare cases are contracted
abroad (de la Rua-Domenech, 2006). For
example, in Australia Mycobacterium bovis
represented 0.2% of all human TB cases in
2010, and M. bovis infection is linked with
employment in the livestock industry and immi-
gration from countries in which bovine TB is
endemic (Ingram et al., 2010). In the USA,
between 1995 and 2005, the majority of human
M. bovis patients were born outside of the USA
and could have contracted zoonotic TB abroad.
In addition, the consumption of fresh cheese
(‘queso fresco’) produced from unpasteurized
milk in Mexico has been described to be a poten-
tial source of M. bovis in the USA (Hlavsa et al.,
2008). Mexico is a country where bovine TB has
a high prevalence in cattle, and studies have
found high prevalence in humans (Sreevatsan
et al., 2000; LoBue et al., 2003; de Kantor and
Ritacco, 2006). A recent study described a prev-
alence of 26.2% of M. bovis among human TB
patients (n = 1165) in Mexico. However, this
high proportion of M. bovis among human TB
patients has been explained by the authors
as potentially linked to immunosuppressed
patients; in addition, isolates obtained from HIV-
infected patients accounted for 19.2% of the
local samples in the same study (Bobadilla-del
Valle et al., 2015).
Bovine TB has been previously classified by
the WHO to be a neglected zoonosis in develop-
ing countries, where the public health burden of
bovine TB is high and many risk factors linked to
the transmission and persistence of M. bovis are
present, for example, consumption of unpas-
teurized milk (Ayele et al., 2004). Moreover,
neglected zoonoses such as bovine TB in devel-
oping countries are associated with poverty
(Maudlin et al., 2009). The quantified burden of
zoonotic TB on public health is still not well
known in developing countries. A recent review
of M. bovis among humans in Africa reported a
mean prevalence of 2.8% of M. bovis among
human TB patients. Considering an incidence
rate of 264/100,000 population/year, this
review resulted in a crude estimate of 7 zoonotic
TB cases/100,000 population per year (Müller
et al., 2013); however, more studies are needed
to better investigate the public health burden of
bovine TB in developing countries. In June 2016,
the WHO included zoonotic TB as a priority and
it is now endorsed by the Strategic and Technical
Advisory Group. In order to follow this develop-
ment, OH approaches are needed to continue to
improve the situation.3.3.1 LivestockBovine TB causes economic losses to the live-
stock industry, as it increases mortality and
reduces milk and meat production. It also results
in condemnation of organs and carcasses in the
slaughterhouses when animals show gross visi-
ble lesions suggestive of bovine TB infection
(Michel et al., 2010). To date no study has been
performed in Africa to estimate the productivity
losses in terms of meat and milk caused by
bovine TB.
In Ireland, a study showed that bovine TB
infection caused a decrease of milk production
by 0.5% to 14.6%; however, decreased milk pro-
duction has been shown to be a risk factor for
bovine TB (Boland et al., 2010). These findings
are in line with earlier estimates of milk produc-
tion losses of 10% among tuberculin-positive
animals in the former East Germany (Meisinger,
1970). In Bangladesh, a study showed bovine
TB to be responsible for 18% of milk losses
( Rahman and Samad, 2008). In addition,
annual calving rates are reduced by 5% among
bovine TB-positive animals, thus affecting the
fertility and demographic composition of the
herd (Bernues et al., 1997). Overall, the cost of
bovine TB to the Ethiopian livestock production
systems was estimated at 1% of the net present
value in the rural and 4% to 6% in urban areas
(Tschopp et al., 2012).3.3.2 Human healthThe emergence of drug-resistant M. bovis is an
important public health problem that affects the
success of TB control programmes in many
developing countries, for instance in Mexico
(Vazquez-Chacon et al., 2015). Consequently, it
causes an increased illness burden and financial
losses due to relapses considering the resistance
of M. bovis to a first-line drug (pyrazinamide)