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- Veterinarian Network, in collaboration with RuVASA and RMIS, manages the national disease reporting system, which relies on private veterinarians reporting livestock diseases encountered at the farm level monthly.
- The disease reporting system provides an overview of diseases in a specific practice’s operating region over a year or multiple years and captures data electronically in real-time on a single database.
- Livestock producers and industry stakeholders can access a monthly national map via the RMIS website, indicating regional disease occurrences alongside a detailed report featuring disease awareness, trends, rampant diseases, and priority diseases.
- Bovine brucellosis, a state-controlled bacterial disease transmissible to humans, remains rampant in beef cattle herds, necessitating mandatory reporting to state veterinarians and stringent control measures.
- The disease reporting system highlights Asiatic redwater as a priority cattle disease requiring further research due to its increasing spread and high mortality rates in susceptible herds.
Veterinarian Network in collaboration with the Ruminant Veterinary Association of South Africa (RuVASA) and Red Meat Industry Services (RMIS) are responsible for the national disease reporting system. For the most part, disease reporting is undertaken by private veterinarians working in the livestock industry who each month report the diseases they encounter at farm level.
This reporting by private veterinarians focusses on all diseases and parasites responsible for livestock deaths and losses on farms; the state, on the other hand, focusses on state-controlled and notifiable diseases. Reporting via the private system is done in real time because it is captured electronically on a single database. The reporting system provides an overview of diseases in a specific practice’s operating region over a year or number of years.
A national picture
Livestock producers and other industry role-players are now able to access a national map on a monthly basis via the RMIS website. This map indicates which diseases occur in which region. Veterinarian Network also compiles a national report each month featuring the following subsections:
- Disease awareness: Diseases still prevalent but which can be prevented effectively through vaccination or other specific disease prevention management strategies.
- Rampant diseases: Diseases that mostly require more complex control methods, as well as comprehensive disease management, which includes testing and culling, biosecurity (quarantine) and vaccination, to control or eradicate it.
- Disease trends: Diseases restricted to a certain area and which have now become more widespread, or diseases that have never occurred in the area and are becoming a source of concern.
- Priority diseases: Diseases that lead to major losses and for which there are currently no effective control measures. In many cases, further research is needed to find better solutions.
Disease awareness
The main diseases against which livestock should have been vaccinated by now are the insect-borne viral diseases – these diseases appear a month or so after the beginning of the rain season in the summer rainfall regions. It is slightly different in the winter rainfall region where rain falls in winter but the disease only appears from spring onwards (as soon as the weather turns warm and insects start to hatch).
Lumpy skin disease
A poxvirus is the culprit responsible for lumpy skin disease in cattle. The disease is mainly prevalent from January to March. Looking at the long-term disease incidence (Figure 1), it is evident that many producers are not vaccinating their livestock like they should. The live vaccine available for this single virus strain is highly effective and able to not only prevent the disease, but also induce long-term immunity, especially if administered for a second year.
Figure 1: Lumpy skin disease outbreaks, April 2022 to September 2024.
Three-day stiffsickenss
Three-day stiffsickness is prevalent in beef cattle during the summer breeding season. Replacement heifers (year-old and two-year-old) and breeding bulls are the worst affected. The disease is responsible for sizable milk losses in dairy cattle and in many instances the more fatal form of the disease, which causes pulmonary emphysema and death, is seen in highly susceptible dairy cattle.
Heifers and young bulls receiving the vaccine for the first time should be vaccinated again with the inactivated vaccine. Thereafter, annual vaccination is crucial, and a booster must be given before the start of the period in which the disease typically occurs in a region.
Timing is essential when it comes to three-day stiffsickness, as the vaccine is less immunogenic and vaccination or a booster dose induces a high level of immunity shortly before and during the period in which disease transmission is highest (January to December in the summer rainfall areas). Work directly with the local veterinarian as this will allow him/her to send an early warning once the first cases of the season are noted.
Bluetongue
Bluetongue is a complex, insect-borne disease in sheep; it can also affect cattle although they usually do not exhibit visible disease signs. Sheep can be affected by several different strains of the bluetongue virus. To date, a total of 21 virus serotypes have been isolated in South Africa. Each of the serotypes may cause the disease and there is little or no cross-protection between serotypes. Currently there is no vaccine containing all the different strains of the bluetongue viruses (serotypes).
The live vaccine has 15 different serotypes (five in each fraction) providing high-level immunity. Three injections must be given at an interval of three to four weeks. This is the optimal vaccine for use in young replacement ewes and rams older than six months. Do not vaccinate ewes in early gestation and rams shortly before or during the breeding season.
The new inactivated vaccine contains 11 serotypes. Administer a booster dose three to four weeks after the first vaccine was administered to build protective immunity. Give young sheep their first vaccine after the age of six months. The inactivated vaccine is safe for use in rams and pregnant ewes before and during the breeding season.
Rampant diseases
The most important disease in cattle is the state-controlled disease, bovine brucellosis. This bacterial disease can be transmitted to humans and poses a major risk for livestock producers, herders and veterinarians working with cattle. All disease incidences must be reported to the state veterinarian; he/she will then take control of the disease on the infected farm/s.
State veterinarians are mostly responsible for reporting the disease, but private veterinarians can also do so. The disease distribution maps generated by the epidemiology department of the state veterinary services (Figure 2) clearly show that this disease is rampant, especially in beef cattle herds.
Figure 2: Bovine brucellosis outbreaks, January 2018 to December 2022.
Brucellosis is under control in dairy herds thanks to annual tests and monthly milk ring tests that dairy producers perform to verify that their herds are clean – this is a condition set by dairy buyers.
Rabies
Dogs, jackals, or other carrier animals can transmit rabies to livestock, especially cattle. People that get bitten by a rabid animal or who handle rabies-infected livestock can also contract the disease.
Where rabies occur in livestock, real-time reporting by veterinarians is essential since the disease is limited to certain areas and specific times of the year. Because vaccination against rabies is not part of the standard vaccination plan, it is essential to send an early warning to livestock producers in the area concerned. To limit losses and as an emergency measure, livestock on neighbouring farms and within a 5 to 10km zone should all be vaccinated preventatively. Animals are only protected two weeks after vaccination which is why immediate action and a working early warning system are vital.
Priority diseases
Asiatic redwater is the most important priority cattle disease identified by the disease reporting system as a disease that continues to spread. It is also the leading cause of the rapid onset of death in cattle.
The pantropical blue tick transmits the disease. Unlike African redwater, typical disease signs such as red urine and pale mucous membranes due to internal blood loss, are sometimes absent. The organism that multiplies in the red blood cells causes the cells to clump together, forming microclots in the capillary blood vessels.
In susceptible herds, the approach is to block treat the entire herd to prevent more deaths. A problem that is often encountered is that the residual effect of the block treatment does not last for long, which may indicate the development of resistance to the agent used.
The only current long-term solution is to vaccinate animals to induce immunity, using the blood vaccine. However, the vaccine was unavailable for a long time, which meant producers could not vaccinate their cattle before the first rains and during a time when tick numbers were increasing.
Asiatic redwater has been identified by the disease reporting system as a high priority requiring further research in a bid to find a better and more permanent solution to livestock mortalities. Cases of Asiatic redwater reported by veterinarians in the Free State (where the disease is a major cause for concern) over the past 18 months were widespread throughout the province.
A final word
Disease control at farm level is in the hands of the livestock producer who must find practical solutions in collaboration with his/her local veterinarian. The disease reporting system offers the opportunity to better understand the occurrence and control of livestock diseases, as well as ways of controlling them in a more targeted manner. – Dr Danie Odendaal, Veterinarian Network
For enquiries, phone Dr Danie Odendaal on 082 454 0523.
