Although human Middle-East respiratory syndrome coronavirus (MERS-CoV) infection seems
to be associated with exposure to animals, including camels, identification of the
animal reservoir remains challenging.1, 2, 3 We believe that this gap results from
the fact that surveillance systems for diseases in both human beings and animals remain
fragmented and fail to take into account the social and ecological contexts within
which diseases emerge. Additionally, there is a paucity of data for emerging infectious
diseases in animals, especially camels in east Africa. For example, most MERS-CoV
cases have been identified in the Arabian Peninsula, in places with robust health
care, veterinary care, and disease surveillance. Although preliminary data link some
cases of human MERS-CoV to exposure to dromedary camels or their products,1, 2 reliable
health records of both human beings and animals cannot confirm a causal relationship.
At the same time, many of the camels in the Arabian Peninsula derive from herds in
east Africa, where both human and animal health systems, including surveillance, remain
To understand the potential reservoirs and prevalence of MERS-CoV, and in the absence
of surveillance and clinical data in east Africa, some researchers have tapped into
banked animal and human biological specimen repositories as a proxy for baseline data.
Findings of retrospective serosurveys done between 1983 to 1997 in east Africa showed
that most (up to 81%) camels were exposed or infected as early as 1980.
However, these findings do not consider exposure to other viruses or the potential
sources of exposure. Indeed, although not recognised until now, MERS-CoV infection
seems likely among east African camels, but the lack of surveillance delays its detection.
Further, in human and camel populations, MERS-CoV infections might be masked by other
common comorbidities. Thus, one of the challenges of surveillance is that syndromic
definitions cannot differentiate MERS-CoV from pneumonia, tuberculosis, and other
common respiratory infections; MERS-CoV cases might go undetected in human beings
and in camels, necessitating confirmatory diagnostics.4, 5, 6
In addition to MERS, tuberculosis poses another, arguably more economically important,
zoonotic disease in camels and other livestock in east Africa. The disease is transmitted
from infected animals through bodily fluids, including milk, and might cause up to
10% of the global human tuberculosis burden.
Although no population-based studies of tuberculosis in human or camel populations
in east Africa specify mycobacterium species, data from small studies suggest that
ethnic Somalis' extraordinarily high rates of tuberculosis and extrapulmonary tuberculosis
without high prevalence of HIV/AIDS could be related to their exposure to tuberculosis
in livestock milks.
Even so, little research or policy work has been done to address these potential sources
of spillover and infection. Although tuberculosis interventions in domesticated, non-mobile
livestock have proven successful, surveillance and control for camel herds remain
restricted because of their mobility and the poverty and disintegration of many local
and regional agricultural and health bureaus.
Camels are central to the diets, economies, and cultures of millions of people in
east Africa. Camel milk is typically consumed—and strongly preferred—without pasteurisation
or other processing, and milk and meat economies are mostly unregulated, informal,
and thus outside the purview of governmental and international regulation.
More than 65% of the world's camels are raised by ethnic Somalis in Ethiopia, Somaliland,
and production has increased exponentially in the past 15 years, including among non-Somali
groups in east Africa. Prices for camels have risen as much as ten times
and exports from Africa to the Middle East are increasing substantially.
Despite the importance of camels to so many lives and livelihoods, the absence of
effective monitoring and sustainable disease reporting systems within and between
countries in the region keep proximal populations vulnerable to both anticipated and
unexpected disease outbreaks.
In addition to MERS-CoV and tuberculosis, other emerging infectious diseases linked
to camels include Rift Valley fever, brucellosis, trypanosomiasis, adenovirus, equine
herpes virus, and camelpox. There are gaps in data on each of these, as well as about
the association between different zoonotic diseases in increasing risks of comorbidity.
Research is necessary to understand if and how MERS-CoV or tuberculosis, for example,
might heighten risk of other infections, and vice versa, in both human beings and
animals. As preliminary research on emergent zoonoses in camels suggest, infectious
diseases and surveillance systems cannot be regarded alone or in isolation from their
broader social and ecological environment.