The financial implications of endemic stability as a control strategy for Bovine babesiosis in veld grazing beef production systems of the KwaZulu-Natal Midlands
Edwardes, William Francis Ivor (2019-04)
ENGLISH SUMMARY : The consumption of beef products in South Africa is expected to increase by 24% in the next ten years. To achieve the production levels, efficiency need to be optimised. Production challenges arise as a result of climatic changes, policy implementations, pests and production diseases of which the myriad of tick-borne diseases present in South Africa form a large component. One of the most economically important tick-borne disease is Bovine babesiosis and has carried this label for at least 35 years. Despite its importance, little economic research was conducted within South Africa boarders. Bovine babesiosis is caused after a tick vector, either Rhipicephalus decoloratus or Rhipicephalus microplus, transmits a Babesia bigemina or the more virulent Babesia bovis parasite to a susceptible bovine. Infection may result in direct production losses such as mortality and weight loss, indirect production losses such as abortions and reduced fertility which are all translated into revenue forgone. Expenditures incurred due to preventive and treatment measures as well as maintenance costs such as compensatory feed. The concept of endemic stability whereby little to no evidence of clinical disease occurs, has long been an epizootioligical principle discussed as a control strategy for Bovine babesiosis. To achieve endemic stability, a strategic dipping routine is implemented exposing cattle to a tick challenge in order to promote the development of endemic stability through parasite transmission. Farmers shifting from intensive dipping towards the strategic option is encouraged by veterinarians, but little is known about the economic and financial implications. This study attempts to fill this gap in the knowledge by exploring the financial and economic implications of either prevention method within beef farms of KwaZulu-Natal Midlands. This was achieved by developing a dynamic stochastic model which simulates a stable herd of 100 cow-spaces over a period of 15 years. Scenarios at varying seroprevalence rates were simulated to compare the economic impact incurred for either dipping strategy, to analyse the results financially, and therefore provide insight as to whether a farmer should focus on maintaining the intensive dipping option or to promote the development of endemic stability. Extreme intensive dipping in the attempt to eradicate tick-vectors is not in the scope of this study. Results indicate that Babesia bovis infections are a cause for greater concern as it may translate into damages up to twenty-fold the economic impact of Babesia bigemina. Overall results indicate that intensive dipping results in a smaller economic impact than strategic dipping except in a scenario of 90% Babesia bigemina seroprevalence. The value of weight lost is responsible for the largest component of the total economic cost. Financial indicators determine that intensive dipping is the more feasible method of prevention for all simulated scenarios of either parasite except for where a 90% Babesia bovis seroprevalence exists. With decreasing seroprevalence rates, the economic consequences decrease while the NPV and IRR increase for an intensive dipping strategy suggesting that the eradication of tick vectors in the attempt to achieve a disease free situation should result in greater production efficiencies.
AFRIKAANSE OPSOMMING : Die verbruik van beesvleis produkte in Suid-Afrika sal na verwagting met 24% toeneem oor die volgende tien jaar. Om die nodige produksievlakke te bereik sal doeltreffendheid van produksie moet toeneem. Produksie uitdagings kom voor weens klimaatsveranderings, beleid implementering, peste en plae, waarvan die verskeidenheid bosluis oorgedraagde siektes in Suid-Afrika ’n groot komponent uitmaak. Een van die ekonomies belangrikste bosluis oorgedraagde siektes, reeds vir 35 jaar, is Bovine babioses. Ondanks die belangrikheid daarvan is daar beperkte ekonomiese navorsing op die siekte binne Suid-Afrika gedoen. Bovine babesiosis word veroorsaak deur ’n bosluis vektor; of Rhipicephalus decoloratus of Rhipicephalus microplus, versprei Babesia bigemina of die meer kwaadaardige Babesia bovis parasiet na ’n vatbare gasheer. Infeksie kan produksie verlies tot gevolg hê, soos gewigsverlies en laer vrugbaarheid en abortering wat direkte finansiële verlies veroorsaak. Kostes kan verhoog weens voorkomende en onderhoudende aksies soos dip en spuit programme en byvoeding. Die konsep van endemies stabiliteit waar geen of min voorkoms van kliniese siekte sigbaar is, word lank reeds as ’n klinies dierkundige beginsel bespreek as beheer strategie vir Bovine babesiosis. Ten einde endemiese stabiliteit te bereik word ’n strategiese dip program gevolg wat beeste blootstel aan bosluis besmetting om die weerstand teen infeksie deur parasiet oordrag te verhoog. Produsente van oorskakel van die intensiewe dip opsie na endemiese stabiliteit word deur vee-artse ondersteun, maar daar is min kennis aangaande die finansiële implikasies. Die studie poog om hierdie gaping te vul deur die finansiële implikasies te ondersoek van beide beheer maatreëls op plaasvlak in die KwaZulu-Natal Middellande. Die doel is bereik deur die ontwikkeling van ’n dinamiese stochastiese model wat ’n stabiele kudde van 100 beeste oor 15 jaar simuleer. Scenario’s teen verskillende weidingsvoorkoms koerse is gesimuleer om die impak te vergelyk van die verskillende dip strategieë. Die resultate verskaf insig in die opsie om intensief te dip of oor te skakel na strategiese dip met gepaardgaande endemiese stabiliteit opbou. Ekstreme intensiewe dip, as strategie om van die bosluis as draer uit te roei, was nie deel van die omvang van hierdie studie. Resultate wys dat Babesia bovis infeksie groter gevaar inhou as Babesia bigemina en skade kan soveel as 20 keer meer wees in finansiële terme. Algehele resultate wys dat intensiewe dip ’n kleiner finansiële impak het as strategiese dip, behalwe vir die scenario waar 90% van die bosluis populasie Babesia bigemina is. Die waarde van gewigsverlies is die grootste bydraer tot algehele finansiële impak. Finansiële indikasies wys dat intensiewe dip die meer lewensvatbare opsie is vir alle scenario’s, behalwe waar 90% Babesia bovis voorkoms is. Teen laer bosluis voorkoms koerse verlaag die NHW (netto huidige waarde) en die IOK (interne opbrengskoers van kapitaal investering) vir ’n intensiewe dip strategie wat sinspeel daarop dat die uitwissing van die bosluispopulasie ten einde infeksie te verlaag die mees doeltreffende strategies behoort te wees.
Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/105999