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The overall driver of disease trends during January 2025 was fast changing environmental factors. Interactions between the following main factors give rise to the occurrence (prevalence) and changes in disease occurrences over a specific time period (incidence) per geographical area:
- Environment (rainfall, temperature, wind, grazing, soil, minerals, nutrition, farm management).
- Type of animal (species, breed, age, stage of production, size of herd, level of herd resistance).
- Specific disease-causing organisms and factors present.
Conditions in December 2024/January 2025
During the first half of December 2024 a heat wave persisted throughout the summer rainfall area and conditions were very dry with very limited grazing. This coincided with the start of the breeding season. Heat waves have a major effect on reproduction performance.
Due to the hot but very dry weather disease problems in the summer rainfall area were limited. Most of the regular insect transmissible summer disease problems depend on the availability of moisture.
During the second half of December 2024 and especially during January 2025, high to abnormal rainfall was prevalent in especially the northern (Limpopo, Gauteng and northern parts of the Free State), eastern (Mpumalanga and KwaZulu-Natal), and western (North West) parts of the summer rainfall area. This was accompanied by relatively low temperatures and less sunshine.
Large parts of the summer rainfall area remained dry during January with limited grazing and even drought.
Along with the good rain in the areas mentioned previously a sudden increase was reported of insect transmissible diseases (lumpy skin disease, three-day stiffsickness and bluetongue) by the end of January. This was, however, much lower than the severe outbreaks experienced in 2022 and 2023 (see Figure 1 containing the lumpy skin disease report for 2018-2024). With autumn’s colder weather setting in, these cases can be expected to remain at lower levels than in years with peak outbreaks during autumn.
Figure 1: Lumpy skin disease report, 2018 to 2024.
Veterinary support
All veterinary practices that report diseases, are also members a WhatsApp group, making communication with these veterinarians immediate and feedback can also be obtained within one day from most of these veterinarians. Currently, 300 veterinarians representing 175 practices are participating in the national disease reporting system and dedicate their time and efforts to also participate in WhatsApp polls, the goal being to obtain even more feedback regarding specific diseases.
The purpose behind this is to identify problem or priority diseases for which a active plan must be set up to find better treatment or prevention solutions through a focussed approach or further research. Figure 2 contains an example of the type of feedback obtained from veterinarians during such WhatsApp polls. Eye infections, for example, is a constant or ongoing problem, one of the reasons being that it can be caused by a high number of disease-causing organisms (bacteria and viruses) and environmental conditions can also be major predisposing factors.
Figure 2: Example of WhatsApp poll feedback from veterinarians.
These replies are then added to the disease reporting system as well as disease distribution maps displayed on the Red Meat Industry Services (RMIS) website at www.rmis.co.za.
Use of polls to gather disease information
Our focus as veterinarians is to drive a project by doing more diagnostic work to identify the most common infectious causes to see whether a more standard approach to prevention (possibly a local produced vaccine) or more targeted use of antibiotics for treatment is possible.
One of the disease trends that drew attention was a short term increase in the fly population. It was confirmed through the WhatsApp poll system, but upon follow-up most veterinarians confirmed that it was limited to a relatively short period during January amid ideal conditions for the propagation of the fly population (high humidity after rain in the north and a few weeks of high temperatures).
The polls revealed a very low incidence of three-day stiffsickness up until January 2025, which is likely to change to much higher levels in February.
Also revealed was a very low incidence of lumpy skin disease up until January 2025, which is expected to change to much higher levels in February.
The most outstanding disease trend and disease priority identified was Asiatic redwater which is the leading cause of acute death in the cattle population in South Africa (Figure 3). One of the most important functions of the disease reporting system is to identify priority diseases and then to take specific action with the limited resources available.
Figure 3: Asiatic redwater, 2018 to 2024.
In respect of Asiatic redwater the following actions will be taken:
- Determining why there are a vaccine shortage and to rectify that.
- Performing diagnostic surveillance in different herds by testing the immune status (laboratory testing of antibody levels) of young cattle (one to two years of age) to gain a more quantified understanding of the problem.
- Undertaking a follow up study involving veterinarians using the vaccine to prevent the disease. This study will involve the following steps:
- Firstly determining whether there are reactions in cattle vaccinated after eight months of age with the live vaccine.
- Determining the risk involved when vaccinating during the period when there is active transmission of the diseases versus vaccinating during winter when there is low risk for natural infection.
- Determining the long-term protection provided by the vaccine in herds that were vaccinated where the veterinarian was involved.
These practical in-field research projects are well on their way and feedback will be given in the February report.
Awareness of maps on the RMIS website
Under the ‘Statistics’ menu on www.rmis.co.za you will find the distribution maps regarding animal diseases reported by Veterinarian Network in conjunction with the Ruminant Veterinary Association of South Africa (RuVASA).
The RMIS is supporting Veterinarian Network which enables us to provide the necessary data needed to populate the disease distribution maps on the RMIS website. This is a huge task Dr Faffa Malan used to perform manually by plotting dots on maps. He retired at the end of December last year and we are very thankful for his dedication and the foundation he has laid for us.
The process is now automated and yields an electronic map with a zoom function to check the prevalence of a specific disease in an area, as reported by participating veterinarians. When hovering with the mouse over the specific reported dot on the map, the information and contact information of the veterinarian that reported the case can also be viewed.
There are three different maps for each disease. To view these maps one has to select the species of livestock and then you select the disease.
The default map is the distribution map containing disease cases over a period of two years.
The second map (click on ‘Seasonal’), provides a indication of the risk of this disease occurring in the next three months based on the data of the previous year.
The third map (click on ‘Current’), gives a indication of the incidence of disease reported in the previous month by the veterinarians.
With the monthly data transfer from Veterinarian Network and electronic mapping by the RMIS now in place, more work will be done to develop a dashboard that will make it easier for livestock producers to view the incidence (level of risk) of the most important diseases in a one-pager format.
Monthly meetings
The latest development in order to communicate with reporting veterinarians and to stimulate better reporting is a monthly online Teams meeting with all participating veterinarians. While this may seem like a small step it is important to recognise the immense contribution these veterinarians are making in terms of time and effort. Without their dedication, the disease reporting system would not exist.
It is important for livestock producers to appreciate the fact that their local veterinarian best understands disease occurrence in his/her practice area and possesses the professional knowledge to diagnose, treat, or give advice on the prevention of these diseases.
To foster better participation and understanding of the value of the disease reporting system, monthly electronic feedback will therefore take place on the first Thursday evening of each month, to further stimulate the finalisation of reporting for the previous month. These meetings will also be registered and added to the CPD points each veterinarian must gather annually.
Areas are unique in their disease makeup
When it comes to interpreting disease problems, there are major differences between different areas. Figure 4 (wireworm in sheep and goats in January 2025) is a good example of this, along with Figure 5 which contains the complete January 2025 report. These documents clearly show that only the veterinarian operating within a specific geographical area can truly understand and interpret the disease problems faced in that area at any given time.
Figure 4: Example of wireworm prevalence in different areas.
Figure 5: Complete January 2025 disease report.
Although we communicate long term-trends and a basic disease distribution to livestock producers, the real interpretation and advice can only be found with the local veterinarian in each geographical area. Support your veterinarian and make him or her your first stop for region-specific advice and information. – Dr Danie Odendaal, Veterinarian Network
