Introduction
In sub-Saharan Africa, rapid urbanisation and per capita consumption of animal
source foods are expected to accelerate in the short-medium term and to increase
the movements of live animals and animal products in the region. In Cameroon,
where the livelihood of most of the rural population depends on the agricultural
and livestock sector, a wide range of endemic transboundary infectious diseases
(TADs) affect livestock production and trade, and have direct detrimental effects
on animal, human and environmental health. Livestock mobility represents a
central economic activity in the livestock value chain of the country as well as a
central strategy of seasonal adaptation to the ecosystem. Livestock movements,
however, are also a central driver of infectious diseases dynamics and contacts
between livestock populations are major risk factors for disease introduction and
circulation. In countries where financial and technical resources are constrained,
such as Cameroon, strategic interventions aiming at the surveillance and control
of multiple infectious diseases simultaneously are essential for optimising their
cost-effectiveness. The overall aim of this study was to apply a methodological
framework to contribute to the understanding of cattle movements in Cameroon
and of their implications for disease circulation.
Methods
This project used a variety of epidemiological and statistical methods to characterise
cattle movements in the country across different scales. The collection
of primary data and information targeted both the formal cattle trade system,
across the country, and the informal seasonal transhumance, across the main livestock
production areas. Between September 2014 and May 2015 diverse strategies
were applied for collecting empirical data and various data sources from multiple
Regions of the country were combined. Cattle trade in Cameroon mainly occurs
via multiple trading points owned and managed either by the veterinary authorities or the municipalities. A total of 62 livestock markets, and the relevant offices
of the Ministry of Livestock, Fisheries and Animal Products (MINEPIA), were
targeted for collecting official data on cattle trade referring to a 12-month period
ranging between September 2013 and August 2014. Additionally, a questionnaire-based
survey with the various livestock markets stakeholders (herders, traders,
butchers and veterinary officials) was carried out to collect a variety of information
on the cattle market system. During this 9-month period of field work, data
on cattle seasonal transhumance were simultaneously collected using a combination
of GPS-tracking technology and questionnaire-based survey.
Results
Volumes of cattle trade, the type of traded animals and their commercial values
varied over the year and across the Regions of the country included in this study.
Nevertheless, the market supply of live cattle showed similar temporal trends over
the year and across the Regions. Although for almost the entire study area the
peak of traded animals in the market system was in December 2013, the trade
volume was consistently higher during the rainy season (May to September).
On the contrary, the reduction in the trade volume during the dry season was
accompanied by an opposite trend in the cattle price, with their commercial value
being higher during the dry season. Furthermore, a cattle price differential was
highlighted between production Regions and high consumption Regions of the
country.
The highest volume of cattle trade was recorded in the Adamawa Region, which
was the main source of cattle for the country while also receiving animals from
neighbouring countries, such as Chad and Central African Republic. In contrast,
major urban markets in the Littoral and Central Regions were the main receivers
of cattle originating from almost all the other areas of the country. Interestingly,
the North-West Region appeared to be more independent and isolated within
the cattle trade network of Cameroon, particularly receiving few animals from
other Regions. Importantly, there was little variation in the structural characteristics
of the cattle trade network as well as in its properties across seasons,
showing that, despite the seasonality in traded numbers, the network of cattle
moving between markets in Cameroon is very stable. This consistent structure
of the network over the year increases the robustness of strategic targeted interventions.
We found that targeting the top 20% of the most connected markets
would significantly reduce the network cohesiveness providing opportunities for
strategic disease surveillance, communication and risk mitigation interventions.
The centrality of the market within the trading network was also found to be
positively associated with the price of live cattle, which tended to be heavily
affected by phenotypic characteristics of the traded cattle. The seasonal cattle
transhumance has been found as a common and widespread practice for herders
attending the market system across whole the study area, highlighting the close
relation between formal trading movements and informal pastoral movements
across the country. Transhumant herds were observed to undertake migrations
across multiple Regions for period exceeding 6 months and showing the potential
for multiple types of interactions with domestic and wild animals.
Discussion
Multiple livestock infectious diseases were identified as being related to the cattle
trade system. As neighbouring and non-neighbouring countries were found to
be epidemiologically connected it is clear that national strategies for surveillance
and control are likely to have limited effectiveness. Regional coordination for designing
and implementing prevention and mitigation strategies against infectious
diseases is essential to improve animal health also at national level. This study
highlights the opportunity for strategic surveillance, control and communication
interventions targeting key livestock markets and Regions of Cameroon. Live
cattle price and centrality of markets, represented by their connectedness within
the trading network, highlights the need to further investigate the links between
economic factors and drivers of disease dynamics, such as livestock movements.
The complexity of cattle movements in this context was further evidenced by
the seasonal transhumance representing an established common mechanism for
managing livestock, and closely interacting with the formal trading system as
well as with other domestic and wild animal populations. Better data collection
and analysis of livestock movements is required for improving the effectiveness of
surveillance and control of infectious diseases. Although animal identification and
registration systems would represent an ideal step for increasing traceability of
cattle movements, enhancing animal health management and the overall competitiveness
of the livestock industry, in the short-term a cost-effective intervention
should aim at further developing the current data recording and management
systems. Pastoralism, for long seen as an economic and environmental activity
with little future, also needs to be acknowledged as a key component of the livestock
production system in the country and to be considered accordingly in the
management of infectious diseases