Economic Significance of Tropical Theileriosis on a Holstein Friesian Dairy Farm in Pakistan.

The dairy industry in Pakistan is booming, and investors are anxious to fund dairy farms that are using high-milk-producing (exotic) cattle breeds such as Holstein Friesians that are not native to the country. Unfortunately, the benefits of increased milk production do not provide resistance to pathogens present in regions where the exotic breeds are introduced. Therefore, the current study was conducted to evaluate the economic impact of Theileria annulata on a commercial Holstein Friesian dairy farm in the District of Ranjanpur, in the Province of Punjab, Pakistan. The economic impact of T. annulata infection was calculated for cattle with subclinical and clinical theileriosis. Losses were estimated based on milk production, morbidity, mortality, and tick control costs (organophosphate sprays). Animals were classified into groups after screening for mastitis, teat abnormality, abnormal parturition, intestinal parasites, and hemoparasites ( T. annulata, Babesia spp., and Anaplasma spp.). Microscopy was done for hemoparasites and intestinal parasites. PCR was used to confirm microscopic identification of T. annulata. Animals were classified into 3 groups: group A (normal), group B (subclinical theileriosis), and group C (acute theileriosis). Hemoparasites were observed microscopically in 28.7% of cows. Theileria annulata was found in 8%, and the herd incidence (new cases) of T. annulata was 2.8%. Milk production, animal rectal temperature, and body condition scores between group A and groups B and C were significantly different ( P < 0.05). But the enlargement of sub-scapular lymph node and interval of body condition score of the 3 groups were not significant ( P > 0.05). The total expenditure incurred due to theileriosis was US $74.98 per animal and 13.83% of total farm costs. Hence theileriosis caused significant economic loss of US $18,743.76 (0.02 million) on this Holstein Friesian dairy.

Current situation of tropical theileriosis in the Sudan.

Tropical theileriosis has long been recognized as a hindrance to the development of sound dairy industry in the Sudan and is a cause of major economic losses. Serological surveys indicated that Theileria annulata infection is widespread in the country but the disease mostly affects exotic dairy breeds and their crosses with indigenous breeds. The disease has recently been identified in Darfur and southern parts of Blue Nile State in dairy farms around large urban areas where it has never been detected before. These new introductions were accompanied by the establishment of Hyalomma anatolicum tick which is the main vector of the parasite in the Sudan. The disease is routinely diagnosed using microscopic examination of stained blood and lymph node biopsy smears. More advanced techniques are mainly used for research purposes. Tropical theileriosis in the Sudan is mainly controlled by using anti-theilerial drugs and acaricide application. It is recommended that live attenuated schizont vaccines developed from locally isolated T. annulata strains be used to control the disease. In addition, every care should be taken to prevent introduction of the disease into new areas.

Ranking control options for tropical theileriosis in at-risk dairy cattle in Tunisia, using benefit-cost analysis.

An economic evaluation of various control programmes against Theileria annulata infection was conducted on a sample of 49 Tunisian dairy farms where clinical cases of tropical theileriosis had been recorded during the summer. Indicators of morbidity and the prevalence of infection, as well as production and demographic indicators (recorded in the present survey ortaken from secondary sources), were used to rank the potential costs and benefits of various control programmes for tropical theileriosis over a time horizon of 15 years. Three options were considered, i.e. vaccination with a local attenuated cell-line vaccine; partial barn upgrading, based on first roughcasting then smoothing all the walls of the animal premises (inner and outer surfaces); and applying acaricides to control the vector tick population on the cattle. The most important loss from this disease, representing between 22% and 38% of the overall losses, is the loss in milk yield from carriers of T. annulata. Upgrading barns produced the highest mean benefit-cost ratio (1.62 to 3.71), while the ratios for vaccination and acaricides ranged from 0.20 to 1.19 and 0.32 to 0.88, respectively. However, the benefit-cost ratio of vaccination increased (from 1.65 to 5.41), when the costs due to carrier state infection, which vaccination does not prevent, were ignored. Upgrading barns is a sustainable eradication policy against tropical theileriosis, based on a single investment, and is environmentally friendly. This control option should be encouraged by national Veterinary Authorities in regions where tropical theileriosis is transmitted by a domestic endophilic tick.

Assessing the impact of East Coast Fever immunisation by the infection and treatment method in Tanzanian pastoralist systems.

A field trial was carried out in a Maasai homestead to assess the impact of East Coast Fever (ECF) immunisation by the infection and treatment method (ITM) with the Muguga Cocktail on the occurrence of this disease in Tanzanian pastoralist systems. These data were further used in partial budgeting and decision analysis to evaluate and compare the value of the control strategy. Overall, ITM was shown to be a cost-effective control option. While one ECF case was registered in the immunised group, 24 cases occurred amongst non-immunised calves. A significant negative association between immunisation and ECF cases occurrence was observed (p≤0.001). ECF mortality rate was also lower in the immunised group. However, as anti-theilerial treatment was given to all diseased calves, no significant negative association between immunisation and ECF mortality was found. Both groups showed an overall similar immunological pattern with high and increasing percentages of seropositive calves throughout the study. This, combined with the temporal distribution of cases in the non-immunised group, suggested the establishment of endemic stability. Furthermore, the economic analysis showed that ITM generated a profit estimated to be 7250 TZS (1 USD=1300 TZS) per vaccinated calf, and demonstrated that it was a better control measure than natural infection and subsequent treatment.

Live immunization against East Coast fever--current status.

The infection-and-treatment method (ITM) for immunization of cattle against East Coast fever has historically been used only on a limited scale because of logistical and policy constraints. Recent large-scale deployment among pastoralists in Tanzania has stimulated demand. Concurrently, a suite of molecular tools, developed from the Theileria parva genome, has enabled improved quality control of the immunizing stabilate and post-immunization monitoring of the efficacy and biological impact of ITM in the field. This article outlines the current status of ITM immunization in the field, with associated developments in the molecular epidemiology of T. parva.

Current status of ruminant theileriosis and its economical impact in Turkey.

The diagnosis of ruminant theileriosis in Turkey is based on microscopical examination of thin blood and lymph smears, serology, traditional staining methods of the salivary glands of ticks and molecular techniques. Although some investigators reported that T. mutans was found in cattle with microscopic examination (7.4%-36.7%) and experimental study, they did not detect this parasite using molecular techniques. On the other hand, the prevalence of T. buffeli/orientalis was found to differ between 0.9% and 13.6% using molecular techniques in different regions of Turkey. Tropical theileriosis caused by T. annulata is widespread, and constitutes a major health and management problem in cattle in Turkey. The economic losses resulting from the tropical theileriosis were estimated to be US $598,000, $133,000 and $130,000 in the endemic stable zones of Turkey. Microscopic prevalence of T. annulata has been reported to be between 0% and 60.5% in different parts of Turkey. The serologic prevalence of T. annulata was found to differ between 1.8% and 91.4% by IFAT. In subsequent studies, the prevalence of this parasite was found to differ between 15.4% and 61.2% by molecular techniques. Clinical cases of ovine theileriosis have not been documented in Turkey. The prevalence of T. ovis/recondita was found to differ between 0% and 41.3% by microscopic examination of thin blood smears and its seroprevalence was found to be between 8.2% and 63.2% by IFAT. This parasite has also been reported to be present between 41.8% and 67.7% by molecular techniques.

The transfer of East Coast fever immunisation to veterinary paraprofessionals in Zambia.

In eastern Zambia, immunisation by 'infection and treatment' is the main method used to control East Coast fever, an acute and lethal cattle disease. This service, which requires a stringent cold chain, used to be free of charge. When a minimal user fee was introduced, attendance dropped drastically. Consequently, this complex immunisation programme was transferred to veterinary paraprofessionals working on their own account, with the aim of boosting a more sustainable distribution of vaccine. Paraprofessionals were provided with a motorbike and the required specific equipment, but fuel and drugs were at their expenses. The paraprofessionals recovered their costs, with a profit margin, by charging the cattle owners for immunisation. The reasons for the successful transfer of immunisation to paraprofessionals (despite the maintenance of a fee) are attributed mainly to the absence of information asymmetry between the paraprofessional and the livestock owner, the appreciable level of effort of the paraprofessionals and the verifiable outcome of the service provided.

Economical impact of tropical theileriosis in the Cappadocia region of Turkey.

This study was initiated to investigate the economical impact of vaccination against tropical theileriosis in cattle in Cappadocia in Turkey. A total of 554 vaccinated and non-vaccinated animals were monitored for Theileria annulata infection using microscopic examination serology by measuring the antibody response of the animals by the indirect immunofluorescence antibody test (IFAT). The prevalence of T. annulata infection, morbidity and mortality were significantly higher in unvaccinated than in vaccinated cattle, whereas the seropositivity was significantly lower in the unvaccinated group. Acute tropical theileriosis cases were diagnosed in 156 of 554 (27.61%) cattle, and 86 of 156 (56.21%) died from the disease. The total economic losses because of tropical theileriosis were estimated at US $598,133 for 2 years.

Epidemiological aspects and economic impact of bovine theileriosis (East Coast fever) and its control: a preliminary assessment with special reference to Kibaha district, Tanzania.

A cross-sectional study based on clinical examination, inspection of herd health records and a questionnaire was designed to determine the epidemiology, economics and potential impact of immunisation against theileriosis in Tanzania. The results showed annual theileriosis costs to be US$ 205.40 per head, whereas the introduction of immunisation reduced this by 40-68% depending on the post immunisation dipping strategy adopted. Morbidity risk due to theileriosis was 0.048 in immunised and 0.235 in non-immunised cattle, and the difference was significant (chi(2)=66.7; P=0.000). The questionnaire results indicated that immunised cattle had a significantly (chi(2)=6; P=0.015) higher risk of anaplasmosis compared with non-immunised cattle, whereas the risk of bovine babesiosis did not differ significantly (chi(2)=0.06; P=0.807) between the two groups. Mortality risk due to anaplasmosis was 0.046 in immunised and 0.018 in non-immunised cattle and this difference was statistically significant (chi(2)=4.48; P=0.043). The theileriosis mortality risk was 0.203 in the non-immunised cattle, while the risk was 0.009 in the immunised cattle and these differences were also significant (chi(2)=103; P=0.000). It was concluded that farmers who have immunised their cattle may cautiously cut down acaricide application by 50% for extensively grazed herds and by 75% for zero grazed animals depending on the level of tick challenge at the herd level.

Estimated direct economic costs associated with tick-borne diseases on cattle in Tanzania.

Tick-borne diseases, namely, anaplasmosis, babesiosis, cowdriosis and theileriosis, constrain cattle production and improvement in Tanzania, leading to considerable economic losses. A simple spreadsheet model was used to estimate the economic losses resulting from production losses, treatment and control costs associated with tick-borne diseases (TBD) in Tanzania. Model parameters included the national cattle population, reported TBD morbidity, fatality risk, and chemotherapy and control measures used. The total annual national loss due TBD was estimated to be 364 million USD, including an estimated mortality of 1.3 million cattle. Theileriosis accounted for 68% of the total loss, while anaplasmosis and babesiosis each accounted for 13% and cowdriosis accounted for 6% of the total loss. Costs associated with mortality, chemotherapy and acaricide application accounted for 49%, 21% and 14% of the total estimated annual TBD losses, respectively, infection and treatment method milk loss and weight loss accounted for 1%, 6% and 9% of the total annual loss, respectively. Despite the inadequacies of the data used, the results give evidence that tick-borne diseases inflict substantial economic losses on cattle production and resource use in Tanzania.

Infection of calves with Theileria annulata in Tunisia: Economic analysis and evaluation of the potential benefit of vaccination.

A field study aiming to estimate the costs of tropical theileriosis was carried out in an endemic region of the North of Tunisia. Three farms were monitored for two successive summer seasons. A total number of 56 calves and 12 sentinel cows were monitored. Calves were ranked into four groups: non infected animals, diseased animals with clinical tropical theileriosis, sub-clinical Theileria annulata infected animals with anaemia and sub-clinical T. annulata infected animals without anaemia. The total costs due to disease and infection were estimated to be 15,115.058 TD (Euro 9388.20). A high proportion of these costs (50.81%) is accounted for by asymptomatic infection. Sub-clinical infections with anaemia showed the highest losses in live weight, while disease cases (prevalence 42.86%) are responsible for 23.64% of the losses with death as the most important element. A cost-benefit analysis of vaccination using a Tunisian attenuated cell line vaccine was also undertaken. Considering that the vaccine would cost 5 TD (Euro 3.10), the cost-benefit ratio of vaccination is 23.7. Sensitivity analysis of the vaccination costs shows that the indifference decision point is around 118 TD (Euro 73.29).

Theileria parva epidemics: a case study in eastern Zambia.

This paper presents the results of the follow-up of three sentinel herds between 1994 and 2000 during an East Coast fever (ECF) epidemic in eastern Zambia. The animals of the sentinel herds were closely monitored clinically and serologically together with detailed Rhipicephalus appendiculatus counts. Peaks of disease incidence occurred in the rainy season (December-February) and the dry months of May-July with nymph-to-adult tick transmission dominating the infection dynamics. A second wave of adult R. appendiculatus at the start of the dry season is essential for the occurrence of a full-blown epidemic while the size of the susceptible cattle population acts as a most important limiting factor. The majority of adult cattle of the sentinel herds became infected less than 2 years after the introduction of the disease. The median age at first contact for calves born towards the end of the study (1999) was about 6 months. The case-fatality ratio (including sub-clinical cases) is estimated at 60%. It is argued that part of the so-called 'natural mortality' is actually due to ECF and that ECF occurrence and mortality are systematically underestimated. The direct financial cost of the epidemic, based on loss of animals and cost of treatment only and calculated over 4 years running, is estimated at about 6 US dollars per year per animal at risk. The value of the traditional seroprevalence survey as a tool for monitoring ECF epidemiology is put in question and the prevalence of maternal antibodies in new-born calves, reflecting the immune status of the dam population, is introduced as an alternative. It is demonstrated that an efficient immunisation campaign should concentrate its efforts in the period of low adult R. appendiculatus abundance (July-October).

Economics of theileriosis control in Zambia.

For an economic analysis of theileriosis control, we adopted the total economic cost (TEC) method, which calculates the sum of output losses from tick damage, theileriosis mortality and morbidity, and expenditures for treatment or prevention of the disease. At farm level, the TEC can be minimized by a specific combination of vector control and/or immunization and an acceptable level of losses. Expenditures for vector control include acaricides, construction of dipping or spraying facilities and their maintenance, and variable costs such as those for water and labour. Economics of vector control depend on the herd size and the method of application of the acaricide. Morbidity, mortality and tick damage losses are effectively reduced by correct and intensive vector control programmes. Expenditures for vector control are estimated at US$ 8. 43, 13.62 and 21.09 per animal per year for plunge dipping, hand spraying and pour-on, respectively. Immunization costs comprise production of parasite stabilates, storage and application, delivery and treatment. At US$ 9.5 per animal, immunization limits losses caused by Theileria parva, but ticks still may reduce the productivity of the animals. Expenditures for treatment after natural infection involve drugs, transport, veterinary fees and farm labour costs. Treatment has a moderate success rate, hence both morbidity and mortality remain important factors. Equally, it does not affect the vector, which may continue to reduce overall productivity of cattle. Expenditures for treatment range between US$ 9.04 and US$ 27.31 per animal. To compare different TECs in relation to different control strategies, assumptions have to be made on disease occurrence, case fatality, value and productivity of the cattle, reductions in productivity due to morbidity and number of animals under a specific control regime. Calculations based on data from Southern Province, Zambia show that large-scale immunization reduces the TEC by 90% compared to no intervention. Treatment, which is the second-best option, reduces the TEC by 60%. Appendix 1 Summary of factors influencing total economic cost

Theileriosis control modelling (experiences from Southern Province, Zambia).

Effects of different tick-borne disease control strategies on cattle productivity are simulated based on a 30-year herd projection, calculated by a modified Markov Chain model. Input data can be grouped in technical, economic and epidemiological parameters. The output is a set of economic parameters such as benefit/cost ratio (BCR), net present value (NPV) of the profit, internal rate of return (IRR), total economic cost (TEC) as well as graphs showing animal production over time. Shadow prices are obtained for input and output in kind. Throughout the calculations a distinction is made between transactions in cash and transactions in kind. A case study was run for Southern Province, Zambia, to illustrate the model. Either vector control or treatment, or a combination of these, controls theileriosis at farm level after natural infection. Preventive immunization against the parasite is also possible. Although the calculations are based on a mixture of data obtained from literature, field experience, expert opinion and assumptions, the importance of theileriosis control is clearly indicated. Immunization gives better economic results than chemotherapy. Vector control can only be used as a last resort.

Cost analysis of immunisation against east coast fever on smallholder dairy farms in Kenya.

A spreadsheet model was developed and used to estimate the total cost of immunising cattle against East Coast fever (ECF) based on the infection-and-treatment method. Using data from an immunisation trial carried out on 102 calves and yearlings on 64 farms in the Githunguri division, Kiambu district, Kenya, a reference base scenario of a mean herd of five animals, a 10% rate of reaction to immunisation and a 2-day interval monitoring regimen (a total of 10 farm visits) was simulated. Under these conditions, the mean cost of immunisation per animal was US$16.48 (Ksh 955.78); this was equivalent to US$82.39 (Ksh 4778.90) per five-animal farm. A commonly reported reactor rate of 3% would decrease the cost of US$14.63 (Ksh 848.29) per animal. Reducing the number of farm monitoring visits from 10 to 7 would reduce the total cost by 10%, justified if farmers are trained to undertake some of the monitoring work. The fixed costs were 53% of the total cost of immunisation per farm. The cost of immunisation decreased with increasing number of animals per farm, showing economies of scale.

General review of tick-borne diseases of sheep and goats world-wide.

A general review of the tick-borne diseases of sheep and goats is given, with the emphasis on those thought to be of greatest economic importance. These include babesiosis, theileriosis, cowdriosis, anaplasmosis, ehrlichiosis, Nairobi sheep diseases and tick paralysis. A commented list of tick-borne diseases and their vectors is presented. It is stressed that large gaps remain in our knowledge of the real importance in the field of many of these diseases, especially in local stock.

Immunisation of cattle in Zimbabwe using Theileria parva (Boleni) without concurrent tetracycline therapy.

Five hundred and ten cattle were immunised using the Theileria parva (Boleni) stock without concurrent chemotherapy with tetracycline on 2 farms in Zimbabwe, both of which had a history of theileriosis. The stabilate had been titrated in Friesian calves to determine a 50% protective dose (PD50) and 2 or 3 (PD50s) were used to immunise the cattle. None of the cattle showed a clinical reaction following the immunisation procedure. However, the cattle were shown to have responded immunologically on testing for antibodies to a T. parva antigen in an indirect fluorescent antibody test. The immunised cattle were then exposed to a natural field challenge causing severe theileriosis in control cattle. Immunisation against theileriosis without the need for concurrent chemotherapy is much less expensive than the infection and treatment method (US $2.72) compared to US $10.23 in the first year) and would be much more attractive to commercial and traditional farmers.

Effects of immunisation against Theileria parva on beef cattle productivity and economics of control options.

Over 500 cattle of all age groups on 2 farms in Zimbabwe were immunised against theileriosis using the "infection and treatment" method and disease prevalence and their productivity assessed during a period of 18 months. The immunising stock, Theileria parva (Boleni) was isolated in Zimbabwe. None of the immunised cattle suffered from theileriosis upon natural exposure whereas 22 unimmunised cattle died of theileriosis and a further 48 required treatment for theileriosis. In the first year, some immunised cattle were maintained with minimal threshold dipping (once or twice during the rainy season). During periods of very high tick challenge of 100 to 1,000 Rhipicephalus appendiculatus per animal from January to March, a transient decrease in liveweight gain was observed particularly in cows. However, by the end of the period of observation, the weights had recovered so that intensively dipped and immunised and threshold or strategically dipped groups of cattle showed no significant differences. From the results it was estimated that each engorging female R. appendiculatus caused a temporary depression in weight gain of 8 grams. In young stock the weight loss was exacerbated by the presence of screw worm (Chrysomya bezziana) infestation. It was then possible to define an economically attractive integrated tick and theileriosis control strategy based on these findings, whereby immunised cattle were dipped 6 times between mid-December and mid-March. In this regimen, no weight loss occurred and no cases of screw worm were observed. For each of 3 herd sizes of 250, 500 and 1,000 cattle, comparisons were made of the costs of 4 different control options: (i) Intensive dipping (40 times/year) (ii) Intensive pour-on acaricide treatments (18 times/year) (iii) Theileria immunisation with strategic dipping (6 times/year) (iv) Theileria immunisation with pour-on treatment (4 times/year) It is concluded from these studies that, on farms where theileriosis is a serious problem, immunisation coupled with a strategic dipping programme is economically very attractive. In the year in which immunisation is carried out, costs will be higher than for intensive dipping, but from the second year on, the costs are decreased to approximately 50% of those for intensive dipping.

Assessing the economic impact of immunisation against East Coast fever: a case study in coast province, Kenya.

The cost of immunising cattle against East Coast fever by the infection and treatment method has been calculated for a pilot scheme in Kaloleni Division of the Coast Province of Kenya by using a spreadsheet model. The cost was calculated to be KSh 544 (US$25) per animal (in 1990 values). If a farmer were to bear all this cost, immunisation would be financially profitable in grade cattle, but the benefits of immunisation would not be sufficient to justify the immunisation of zebu cattle. For these animals, the cost of immunisation would have to be in the range of KSh 230 to KSh 415 per animal, or the farm-gate price of milk would have to increase by at least 80 per cent from KSh 7.50 to 13.50/litre, or the government would have to subsidise the cost either partially or fully. The first two possibilities are realistic, because the costs of routine immunisation are likely to be lower than for the pilot scheme, and because the increasing demand for milk is likely to push up prices in the liberalised markets. If both the grade and zebu cattle in Kaloleni Division were targets for immunisation, it is estimated that there would be 14,500 head for immunisation annually, costing an estimated KSh 8 million. The spreadsheet model used to assess the economics of immunisation in the Kaloleni Division could be applied to determine the government or private veterinary service charges for immunisation that would be financially profitable to farmers in a defined cattle production system in any division, district or country. The model could also be used to estimate the annual total number of cattle for immunisation in a target cattle production system and thus help with the financial planning for the exercise.

Treatment of theileriosis in crossbred cattle in the Punjab.

One hundred and nine cases of bovine tropical theileriosis (Theileria annulata infection) in Punjab State, India, were treated with oxytetracycline (23 cases) or buparvaquone (86 cases). Ages of affected cattle ranged from 6 days to 3 years. Oxytetracycline cured only 7 animals (30.4%), all of them calves below 15 days old, while buparvaquone cured all but one (98.8%), a severely affected 10 day old calf. Cured cattle remained theileriosis-free for 12 to 18 months following recovery. Theileriosis in Punjab is predominantly a disease of young calves that cannot be protected by available cell-culture vaccines. It is suggested that the most economical way to control theileriosis in India would be to immunise calves by infection with sporozoite stabilate and simultaneous treatment with tetracycline, and to reserve buparvaquone for the treatment of clinical cases, in cattle of all ages.