22 F. Olea-Popelka et al.
2.3.5 ChildrenIn many regions of the world where bovine TB is
endemic, children frequently consume unpas-
teurized milk. In the US, the predominance of
M. bovis disease among children suggests recent
infection, likely from contaminated food sources
(Dankner and Davis, 2000; Hlavsa et al., 2008).
In the analysis conducted by Scott et al. (2016),
children younger than 15 years of age born in
Mexico or with at least one parent born there
were more likely to have M. bovis infection com-
pared to children born in the US. In children,
severe forms of disease such as disseminated TB
or meningitis are more common, exacerbated by
a late diagnosis due to the fact that they are
dependent on adults for accessing healthcare, do
not easily produce sputum or may have extra-
pulmonary disease.
Two recent paediatric case reports of gas-
trointestinal TB due to M. bovis published by
Anantha et al. (2015) in Canada and Pemartín
et al. (2015) in Spain further highlight the seri-
ous health consequences of M. bovis in children.
The authors emphasized the need for increased
awareness of abdominal TB caused by M. bovis
that may mimic other conditions, resulting in
delayed diagnosis and unnecessary surgery. This
is of particular relevance for foreign-born indi-
viduals who travel periodically to TB-endemic
regions. Another case report in the US by Hang
et al. (2015) of an Hispanic girl with a sub-
mandibular mass caused by M. bovis further
demonstrates the clinical challenges she faced,
including failure of initial two-drug therapy, the
need for surgery, followed by nine additional
months of treatment.
2.3.6 Patient demographicsIn the US, patients with TB caused by M. bovis
are more likely to be Hispanic than patients with
TB caused by M. tuberculosis (LoBue and Moser,
2005; Rodwell et al., 2008; Scott et al., 2016). In
contrast, most zoonotic TB patients in the UK are
white and older, born prior to the introduction
of widespread milk pasteurization, suggesting
re-activation of a latent infection acquired
decades earlier (Mandal et al., 2011). In African
countries, several studies have identified risk fac-
tors for M. bovis transmission to humans, such
as a lack of education including unawareness
of zoonotic TB, consumption of unpasteurized
milk products, and not using protective equip-
ment in abattoirs. In Uganda, Kazoora et al.
(2016) concluded that knowledge of inter-
viewed cattle farmers regarding zoonotic TB
caused by M. bovis in humans was poor. In Nige-
ria, two recent studies regarding knowledge,
attitudes and practices conducted among abat-
toir workers concluded that there is an urgent
need for public health authorities to intervene in
controlling bovine TB (Sa’idu et al., 2015) and
that the knowledge on bovine TB among abat-
toir workers was low (Ismaila et al., 2015). In
Cameroon, Kelly et al. (2016) concluded that the
control of bovine TB under the current cattle
husbandry practices is challenging, particularly
in mobile pastoralist herds, and that the preven-
tion of M. bovis transmission in milk offers the
best approach for human risk mitigation. How-
ever, this requires strategies that improve risk
awareness among producers and consumers. In
Ethiopia, Kidane et al. (2015) found that among
high school students in Adis Ababa, a low pro-
portion of students considered raw milk and
yogurt as sources of M. bovis infection (47.3%
and 15.8%, respectively). It was concluded that
there was a much lower knowledge and aware-
ness of bovine TB among students compared to
human pulmonary TB.
Although extremely rare, transmission of
M. bovis from pets to humans has been docu-
mented. In the UK, Shrikrishna et al. (2009)
documented an owner and her pet dog having
pulmonary TB caused by the same strain of
M. bovis. In Texas, USA, Ramdas et al. (2015)
documented two (indoor) cats suffering from
pulmonary TB caused by M. bovis and discussed
the potential association with at least one house-
hold member, who had died from pulmonary TB
due to M. bovis. Although, the M. bovis strains
did not exactly match, the authors concluded
that the cat and human M. bovis strains were
closely related, and highlighted the challenges
of this unusual case of M. bovis infection. Due to
the scarcity of data on this topic, the potential
public health risk of M. bovis infection in pets
deserves further attention.