THE seasonal resurgence of Theileriosis in Zimbabwe for the past two decades has been cause for concern.
While veterinary research and epidemiology have evolved and improved to address agro-bio-societal changes – chief among them, the eradication of agricultural pests and livestock/animal diseases important for both human and animal survival — a practical national livestock disease elimination programme, engaging veterinary practitioners, is yet to manifest in Zimbabwe.
Animal scientists and veterinary practitioners have the responsibility to protect human health and well-being by ensuring food safety through the prevention and/or controlling animal diseases; preventing emerging infectious zoonoses; protecting environments and ecosystems as well as assisting in the prevention of possible bio-chemical terrorism and agro-terrorism through contaminated agricultural produce, and thus promoting national food security
Veterinary practitioners are also responsible “…for advancing treatments and controlling zoonotic and non-zoonotic diseases (such as vaccine-preventable illnesses and chronic diseases), contributing to public health and engaging in medical research.” (Pappaioanou, 2004)
Despite the importance of veterinary intervention on animal and human welfare, support for it appears to be isolated and inadequate and not commensurate with its overall effect and societal contribution.
Today in Zimbabwe, the much talked about Theileriosis, also known as January Disease, caused by Theileria parva, are very small blood-borne parasite called protozoa continues unabated.
The infective sporozoite stage of the parasite is transmitted in the saliva of infected ticks as they feed.
On a global scale, there are variations in diseases caused by the different species of the parasite, with the most severe being East Coast fever, which is endemic in African countries.
It has long been considered that tropical and sub-tropical climates tend to favour the survival and transmission of the Theileria.
Different species of Theileria cause different diseases in animals, but the two of most concern in South Africa are corridor disease and turning sickness which result in brain damage.
Corridor disease, caused by Theileria parva lawrencei protozoa, is also known as buffelsiekte, as it is spread by buffalo.
It occurs near wild life environs when buffalo come into contact with domesticated animals.
The presence of a single buffalo for a relatively short period may cause a serious outbreak of disease among cattle.
Symptoms of corridor disease include fever, combined with depression, listlessness or standing apart, enlarged glands (lymph nodes, especially below the ear and those in front of the shoulder and the knee), decreased milk production, loss of appetite, watery discharge from eyes, weakness and difficulty in breathing – especially just before death which follows three-to-four days after the first signs of the disease in at least 80 percent of infected animals.
The disease is acute and progresses very quickly. Treatment is usually not possible.
The disease is called ‘corridor disease’ because it was first identified in South Africa in the ‘corridor’ between the Hluhluwe and Umfolozi game reserves in KwaZulu-Natal (KZN).
It currently occurs in Limpopo, Mpumalanga, KZN, Botswana, Mozambique, Angola and Zimbabwe.
After foot-and-mouth disease, it is the second-most important disease transmitted from buffalo to cattle.
Turning sickness occurs in young cattle.
They are infected when bitten by brown ear ticks carrying Theileria taurotragi protozoa.
The disease can occur wherever the ticks are found and usually results in death within a few days of the symptoms appearing, redness and bleeding in the brain and the covering of the brain may be seen in dead animals.
Symptoms include walking in circles – giving the disease its name — staggering, blindness and paralysis.
In its many strains, variants and compounded complications, Theileriosis continues to wreak havoc to livestock throughout susceptible regions in the country this agricultural season (2021-2022), as it has done for the past several seasons, the latest being 400 cattle deaths reported in the Midlands area.
However, numerous others go unrecorded.
The disease, which is usually fatal in cattle, occurs when cattle become infected by Theileria, when bitten by brown ear ticks (rhipicephalus appendiculatus) that carry the disease.
Cattle are also at risk of infection when moved to areas where infected ticks are present.
Although it is not spread by direct animal-to-animal contact, infected animals can also spread the infection to ticks when transported to new areas.
In turn, this can spread the disease to uninfected animals.
Cows, during calving and young calves (two-to-three months), are at most risk from infection.
Cattle can be infected with the Theileria parasite without necessarily showing any signs of clinical disease.
Once the animal is bitten, it takes about six-to-eight weeks for the parasite to build up the significant levels in the blood.
At this stage, the body reacts by trying to destroy the parasite.
Because the parasite is living inside the red blood cells, the body attacks its own infected red blood cells (haemolysis) to destroy the parasite.
Unfortunately, this can lead to a huge loss in red blood cells which are responsible for carrying the oxygen around the body.
This is known as anaemia.
Symptoms in affected animals are: pale or yellow, rather than healthy pink, to not responding as expected to treatment, lack of appetite, decrease in milk production and sudden death, especially in late pregnancy or early lactation.
Signs of anaemia associated with Theileriosis are more likely seen around calving time, in calves (two-to-three months) and if cows are coping with other health challenges or potentially at mating time.
In January (2021), 3 165 cases of tick-borne diseases were recorded, while in February, The Herald reported 3 165 had died during the same period in 2020, with 4 340 cases reported – a decline of 1 175, attributed to the Presidential Blitz Tick Grease Input Scheme.
However, in November 2020, 1 903 cattle died of tick-borne diseases – an increase of 770 from November 2019’s count of 1 133 dead cattle.
Theileria is a widespread disease with an increasing number of cases countrywide.
The new farming season in Zimbabwe (2021-2022) has already witnessed many cases of Theileriosis, including concurrent diseases such as lumpy skin and pink eye diseases compounded by Theileriosis, appearing in all the 10 provinces – an estimated 5 270 cattle dying so far this year (Jan/Feb 2022).
Treatment for Theileriosis is usually unsuccessful; thus, prevention and control are recommended.
The disease can be prevented by vaccination and effective tick control – not tick grease alone.
Fortunately, cattle cannot infect one another and the disease does not continue spreading.
However, it is important to contact a veterinarian immediately if any Theileria symptoms/signs are noticed as Theileriosis is time sensitive and delays can prove fatal and costly.
Given some of the most pressing issues in Zimbabwe today affect the health and food security of the people, the economy and ecology, more financial attention needs to be focussed on permanently eradicating diseases such as Theileriosis in our precious cattle.
The extreme heat wave experienced in Zimbabwe recently, coupled with the increased precipitation and continued environmental degradation, will no doubt result in further animal diseases and crop pests, such as army worm, that Zimbabwean farmers should guard against.
In this light, it is important for Zimbabwe’s relevant authorities to be aware of the various factors that contribute to the health and economic implications of veterinary disease control in Zimbabwe today.
Effective disease control programmes are crucial for improving the health and welfare of Zimbabwe’s agriculture and livestock sectors.
This in turn, will improve the health and well-being of the people, the ecological environment and, in turn, national economic prosperity.
With appropriate agro-veterinary support systems and financial resources, the eradication of Theileriosis in Zimbabwe is feasible if the necessary manpower is sought and mustered to implement a national disease eradication strategy.
Dr Tony Monda is currently conducting veterinary epidemiology, agro-economic and food security research in Zimbabwe and Southern Africa.
For views and comments, email: E-mail: tonym.MONDA@gmail.com