Discussion on a Selection of Key Scientific Articles


Economic effects of foot and mouth disease outbreaks along the cattle marketing chain in Uganda, Veterinary World, 9 ( 6 ), pp. 544-553, Baluka, S.A., 2016.

Key Thoughts:
To change global FMD control and move towards eradication, it is essential that the impact to the cattle owner be properly understood. Individual countries have different dynamics in farming, so it is important to investigate specific cases. This study looks at the economic effects of FMD across the cattle marketing chain, and identifies significant losses to farmers and others involved in Uganda. The total income earned was reduced by 23%, while the losses for bulls and cows were $196.10 and $1552.90, respectively. While all factors were affected, smallholders saw the biggest losses relative to income. This type of information can be essential in discussions with farmers to highlight the real damage done by the disease.

Article Review:
This study aimed to assess the multiple economic effects of FMD across the cattle marketing chain in Uganda by using a combination of qualitative and quantitative approaches.

Low- and middle-income countries account for 75% of the world’s cattle, and yet only account for 15% of the global value. 70% of households in Uganda own livestock of some description, and a high proportion of those derive their livelihood from livestock. This means that disease is a major constraint to trade, and a disease such as FMD limits access to global trade. Outbreaks are associated with movement bans, while the disease imposes heavy costs. 

Focus group discussions (FGDs) and key informant interviews (KIs) were used for the qualitative stages of the study, taking farmers from districts identified from previous FMD outbreak data. Veterinarians were also considered by district, while traders were treated as an aggregate as they operated in multiple districts. FGDs with farmers concentrated on livelihood activities, with cattle traders on supply, sales data, and transport, and with processors on frequency of purchase and size of business. All actors were asked about the impact of the last FMD outbreak. KIs with veterinarians and policy makers concentrated on constraints, outbreaks, and regulations. The use of a structured questionnaire allowed more control over the responses.

Household incomes and market revenues were calculated. Draft power was discounted as not important for the region. Once gross margin analysis was performed, it was possible to determine the economic costs associated with an outbreak.

Labor, treatment, veterinary drugs, acaricides, mineral salts, vaccination, fencing and farm maintenance were the major inputs into the enterprises. Milk, live cattle sales, and manure were the main outputs. Milk yield was affected by the seasons, with prices higher in the dry seasons and falling in the wet seasons. The district of Nakaseke had higher prices and earned more revenue than other districts.

FMD outbreaks lead to a loss of income from reduced milk yield and reduced live cattle sales in all study districts. Overall milk yield dropped 42% in infected animals, and this represented a loss of 12% of milk sales. Importantly, the loss of milk also leads to starvation due to loss of milk for food. There were also additional expenditures in the way of drugs, vaccines, labor, and abortions. Large herds (151-350 head) were less impacted, with no salvage losses. The greatest loss for small herds came from mortality, for medium herds from salvage sale, and for large herds from milk loss.

Smallholder farmers are disproportionately impacted by FMD outbreaks. However, all actors along the chain are affected, as the quarantine periods make it difficult for traders to obtain new stock, and then processors struggle to obtain animals for slaughter.

African horse sickness: The potential for an outbreak in disease-free regions and current disease control and elimination techniques, Equine Veterinary Journal, 48, 659-669. doi:10.1111/evj.12600, Robin, M., Page, P., Archer, D., Baylis, M., 2016.

Key Thoughts:
In the last decade the range of vector-borne diseases has changed. New regions such as Europe are seeing the spread of Bluetongue virus and Schmallenberg virus. As African Horse Sickness (AHS) is an arboviral disease transmitted by Culicoides biting midges, the risk of new outbreaks is significant. Furthermore, there is evidence that the correct conditions are already in place in what are currently considered disease-free countries. An outbreak in one of these countries could have a major impact on equine welfare and industry.

Article Review:
African Horse Sickness (AHS) is a vector-borne disease currently endemic in sub-Saharan Africa. It has a high mortality rate, up to 95% in naïve populations. It is classified as a listed disease by the OIE. The virus consists of 9 serotypes, two of which have previously caused outbreaks outside of sub-Saharan Africa. A number of the serotypes have recently been found in eastern and northern Africa. The principle vector is Culicoides, and both geographical and seasonal distribution of the disease has been dependent on this vector.

A combination of climate change and increasing international movement has been linked to changes in global distribution of other vector-borne disease, and this leads to concerns that AHS may be an increased threat.

Equids do not play a role as long-term carriers, but reservoirs are found in certain equid species where the disease is associated with prolonged viraemia. This allows for continuous cycling. Zebra have been identified as important in this regard, but other species, including donkeys, must also act as reservoir hosts.

Culicoides midges are the primary vector for AHS, and this leads to comparisons with Bluetongue, which is also reliant on the midge. Although there are over 1400 different species, not all of them are capable of virus transmission. However, Culicoides imicola is of primary importance to both diseases and is found in Southern Europe and Asia. The transmission of AHS in midges is dependent on large numbers of Culicoides, and therefore is associated with weather conditions that allow for the development of large populations.

Five scenarios must be considered when assessing risk in disease-free regions:

  1. Altered global distribution of known vector species
  2. Vector role of indigenous species
  3. Viral introduction with infected vertebrates
  4. Viral introduction with infected vectors
  5. Reversion of virulence of vaccine strains

AHS is notifiable in disease-free countries and, if confirmed, the priority is to stop further spread, as outbreaks can lead to significant costs. For example, a potential outbreak in the Netherlands has been estimated to cost $272-516 million. In order to combat losses, certain countries, such as the UK, would implement culling as part of the control strategy. While tracking of horse movement would be another important technique, unfortunately there is no suitable system currently established in the EU.

Vaccination is an option, and is currently used in Africa, but does not cover all serotypes and is not completely protective. As some vaccinated horses may get sub-clinical disease and a viraemia, this may represent a risk of transport around the country, although it is not clear if the viraemia would be sufficient to infect Culicoides. Current vaccines are attenuated and there is some concern regarding reversion to virulence.
Further research is required to prepare for any epidemic of AHS.

Research needs to focus on:

  1. The vector competence of Culicoides species
  2. Improving disease modeling through improved knowledge of Culicoides and equid movement
  3. Prevention of blood feeding by Culicoides
  4. Establishment of vaccine banks


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