1
|
Yawa M, Mtenjwa B, Jaja IF, Mthi S, Nyangiwe N, Tokozwayo S, Rumosa-Gwaze F, Stempa T, Qokweni L. Assessment of knowledge, attitudes, and practices related to the prevalence of sheep scab among communal sheep farmers in Eastern Cape Province, South Africa. Vet World 2024; 17:558-563. [PMID: 38680145 PMCID: PMC11045542 DOI: 10.14202/vetworld.2024.558-563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 02/13/2024] [Indexed: 05/01/2024] Open
Abstract
Background and Aim Sheep scab is one of the most contagious diseases of sheep found in rural communities worldwide and is a major health and welfare concern for sheep farming. Information on the attitudes of communal farmers to sheep scab remains speculative in the Eastern Cape Province. This study aimed to investigate knowledge, attitudes, and practices related to the prevalence of sheep scab among communal sheep farmers in Eastern Cape Province, South Africa. Materials and Methods From June to August 2022, a cross-sectional survey using a semi-structured questionnaire (n = 160) was conducted in two rural communities of the Enoch Mgijima Local Municipality in Eastern Cape Province. Purpose sampling was used to obtain respondents' knowledge, attitudes, and management practices regarding sheep scabs. Results Among respondents, 81% were males and 19% were females. The majority of sheep farmers (59%) in both communities were aware of sheep scabs, but the majority (64%) did not receive any farming training. The majority of sheep farmers (65%) believed that sheep scab was the most serious threat to their sheep production since it increased mortality. In the past 3 years, approximately 57% of respondents reported an increase in the prevalence of sheep scab. The majority of farmers reported wool loss as the most noticeable clinical symptom (73%). More than 80% of sheep farmers do not use acaricide on a regular basis. Sixty-one percent of farmers prefer a pour-on topical application method. The frequency of annual dipping was every fortnight (40%), during summer and winter (24%). Most farmers (66%) regularly vaccinate their sheep. Conclusion The prevalence of sheep scab is increasing in these communities; however, a better understanding of the factors that facilitate its transmission is required to allow improved management and control of this disease. The government must involve extension officers and distribute them to disseminate information to farmers. Thus, it will be easy to translate the literature into action.
Collapse
Affiliation(s)
- Mandla Yawa
- Department of Rural Development and Agrarian Reform, Döhne Agricultural Development Institute, Private Bag X15, Stutterheim 4930, South Africa
- Department of Livestock and Pasture, Faculty of Science and Agriculture, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
| | - Bukeka Mtenjwa
- Department of Livestock and Pasture, Faculty of Science and Agriculture, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
| | - Ishmael Festus Jaja
- Department of Livestock and Pasture, Faculty of Science and Agriculture, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
- Department of Agriculture and Animal Health, University of South Africa, Florida, South Africa
| | - Siza Mthi
- Department of Rural Development and Agrarian Reform, P.O. Box 112, Queenstown 5320, South Africa
| | - Nkululeko Nyangiwe
- Department of Rural Development and Agrarian Reform, Döhne Agricultural Development Institute, Private Bag X15, Stutterheim 4930, South Africa
- Department of Agriculture and Animal Health, University of South Africa, Florida, South Africa
| | - Sive Tokozwayo
- Department of Rural Development and Agrarian Reform, Döhne Agricultural Development Institute, Private Bag X15, Stutterheim 4930, South Africa
| | | | - Thuthuzelwa Stempa
- Department of Rural Development and Agrarian Reform, Private Bag X3090, Butterworth 4960, South Africa
| | - Luxolo Qokweni
- Department of Rural Development and Agrarian Reform, Private Bag X6012, Port Elizabeth 6001, South Africa
| |
Collapse
|
2
|
Lihou K, Wall R, Nixon E. Treatment of sheep prior to movement: its contribution to an effective scab (psoroptic mange) management strategy. Parasit Vectors 2023; 16:436. [PMID: 38007436 PMCID: PMC10676605 DOI: 10.1186/s13071-023-06044-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 11/06/2023] [Indexed: 11/27/2023] Open
Abstract
BACKGROUND Ovine psoroptic mange (sheep scab) is an important disease of sheep worldwide caused by the parasitic mite, Psoroptes ovis. It has a negative impact on animal welfare and leads to significant economic losses for the sheep industry. Effective and targeted management is required to limit its transmission. METHODS A stochastic metapopulation model of sheep scab transmission is used to investigate the contribution of the treatment of sheep prior to movements to sales, gatherings (predominantly markets) and away grazing to the reduction of prevalence of farms with scab in Great Britain. RESULTS Treatment prior to movement to gatherings resulted in an 86% reduction in the overall prevalence of farms with scab and was more effective at reducing the overall prevalence of farms with scab than treatment before other categories of movements. The relative risk of farms having scab infection was inversely related to the percentage of farms which treated, but this relationship was not linear, with the biggest declines in the prevalence of farms with scab being achieved by small percentages of farms treating; a 50% relative reduction in the farm prevalence was achieved with only 15% of farms treating prior to gathering movements. CONCLUSIONS The results suggest that pre-movement treatment of sheep could make an important contribution to national scab control and, in practice, the approach could be more highly targeted if used in conjunction with known geographic and management risk factors for scab.
Collapse
Affiliation(s)
- Katie Lihou
- Department of Engineering Mathematics, University of Bristol, Bristol, UK.
| | - Richard Wall
- School of Biological Sciences, University of Bristol, Bristol, UK
| | - Emily Nixon
- Department of Mathematical Sciences, University of Liverpool, Liverpool, UK
| |
Collapse
|
3
|
Chang Y, de Jong MCM. A novel method to jointly estimate transmission rate and decay rate parameters in environmental transmission models. Epidemics 2023; 42:100672. [PMID: 36738639 DOI: 10.1016/j.epidem.2023.100672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 12/23/2022] [Accepted: 01/26/2023] [Indexed: 02/05/2023] Open
Abstract
In environmental transmission, pathogens transfer from one individual to another via the environment. It is a common transmission mechanism in a wide range of host-pathogen systems. Incorporating environmental transmission in dynamic transmission models is crucial for gauging the effect of interventions, as extrapolating model results to new situations is only valid when the mechanisms are modelled correctly. The challenge in environmental transmission models lies in not jointly identifiable parameters for pathogen shedding, decay, and transmission dynamics. To solve this unidentifiability issue, we present a stochastic environmental transmission model with a novel scaling method for shedding rate parameter and a novel estimation method that distinguishes transmission rate and decay rate parameters. The core of our scaling and estimation method is calculating exposure and relating exposure to infection risks. By scaling shedding rate parameter, we standardize exposure to pathogens contributed by one infectious individual present during one time interval to one. The standardized exposure leads to a standard definition of transmission rate parameter applicable to scenarios with different decay rate parameters. Hence, we unify direct transmission (large decay rate) and environmental transmission in a continuous manner. More importantly, our exposure-based estimation method can correctly estimate back the transmission rate and the decay rate parameters, while the commonly used trajectory-based method failed. The reason is that exposure-based method gives the correct weight to infection data from previous observation periods. The correct estimation from exposure-based method will lead to more reliable predictions of intervention impact. Using the effect of disinfection as an example, we show how incorrectly estimated parameters may lead to incorrect conclusions about the effectiveness of interventions. This illustrates the importance of correct estimation of transmission rate and decay rate parameters for extrapolating environmental transmission models and predicting intervention effects.
Collapse
Affiliation(s)
- You Chang
- Quantitative Veterinary Epidemiology Group, Wageningen Institute of Animal Sciences, the Netherlands.
| | - Mart C M de Jong
- Quantitative Veterinary Epidemiology Group, Wageningen Institute of Animal Sciences, the Netherlands
| |
Collapse
|
4
|
Nixon EJ, Brooks-Pollock E, Wall R. Assessing the effectiveness of prophylactic treatment strategies for sheep scab. Vet Parasitol 2022; 312:109822. [DOI: 10.1016/j.vetpar.2022.109822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 11/29/2022]
|
5
|
Crawford PE, Hamer K, Lovatt F, Robinson PA. Sheep scab in Northern Ireland: Its distribution, costs and farmer knowledge about prevention and control. Prev Vet Med 2022; 205:105682. [DOI: 10.1016/j.prevetmed.2022.105682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 05/21/2022] [Accepted: 05/24/2022] [Indexed: 11/30/2022]
|
6
|
Nixon EJ, Brooks-Pollock E, Wall R. Sheep scab spatial distribution: the roles of transmission pathways. Parasit Vectors 2021; 14:344. [PMID: 34187531 PMCID: PMC8243883 DOI: 10.1186/s13071-021-04850-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/12/2021] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Ovine psoroptic mange (sheep scab) is a highly pathogenic contagious infection caused by the mite Psoroptes ovis. Following 21 years in which scab was eradicated in the UK, it was inadvertently reintroduced in 1972 and, despite the implementation of a range of control methods, its prevalence increased steadily thereafter. Recent reports of resistance to macrocyclic lactone treatments may further exacerbate control problems. A better understanding of the factors that facilitate its transmission are required to allow improved management of this disease. Transmission of infection occurs within and between contiguous sheep farms via infected sheep-to-sheep or sheep-environment contact and through long-distance movements of infected sheep, such as through markets. METHODS A stochastic metapopulation model was used to investigate the impact of different transmission routes on the spatial pattern of outbreaks. A range of model scenarios were considered following the initial infection of a cluster of highly connected contiguous farms. RESULTS Scab spreads between clusters of neighbouring contiguous farms after introduction but when long-distance movements are excluded, infection then self-limits spatially at boundaries where farm connectivity is low. Inclusion of long-distance movements is required to generate the national patterns of disease spread observed. CONCLUSIONS Preventing the movement of scab infested sheep through sales and markets is essential for any national management programme. If effective movement control can be implemented, regional control in geographic areas where farm densities are high would allow more focussed cost-effective scab management.
Collapse
Affiliation(s)
- Emily Joanne Nixon
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK.
| | - Ellen Brooks-Pollock
- Veterinary Public Health, Bristol Veterinary School, University of Bristol, Bristol, BS40 5EZ, UK
- NIHR Health Protection Research Unit in Behavioural Science and Evaluation, University of Bristol, Bristol, UK
| | - Richard Wall
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
| |
Collapse
|