LUGWEG- INFEKSIES IN BEESTE: n Paar vrae beantwoord

Transcription

1 veevernuf stocksense 2013 ISSUE Why is the energy balance in lactating cows so important? Dr Adél de Haast sovereign pour-on: Champion Choice Dr Johan Cloete Zoonoses: Anthrax Dr Mats Abatzidis LUGWEG- INFEKSIES IN BEESTE: n Paar vrae beantwoord Dr Pierre Jansen van Vuren Hoekom ent ons diere? Diere word geënt om sekere siekte toestande te voorkom, dis n voorsorgmaatreël, maar nog steeds kry ons verbruikers wat dink jy kan siek diere ent om hulle gesond te maak. 8 9 MSD Implant range Dr Pierre Jansen van Vuren Hoekom beeste dip in die koue wintermaande? Elize Terblanche & Dr Johan Cloete n Siek dier se immuun stelsel is al klaar onder druk, besig om sy huidige siekte toestand te beveg. Deur hom in te ent terwyl hy siek is, sit ons net meer stres op sy immuun stelsel, wat net negatiewe gevolge het. Wat is Bees Lugweg Infeksie? Bees Lugweg infeksie, bekend as BRD (bovine respiratory disease), is vandag, naas rooiwater, seker die duurste en die mees algemene gesondheidsprobleem in die voerkraal bedryf (1) en gaan dikwels ongesiens verby in n koeikalfsisteem. Verliese beloop biljoene wêreldwyd en biljoene meer word spandeer om seker te maak dat hierdie verliese beperk word. Ons fokus op die virusse omdat hulle die lugweë van die gestresde beeste beskadig. Hulle onderdruk ook die dier se immuunstelsel. Dit veroorsaak gunstige toestande vir bakterieë om te oorgroei en die dier raak net al sieker en kan doodgaan as hy nie vroeg genoeg behandel word nie. Voor jy ent, wat is die omstandighede waaronder die beeste hulle bevind tydens enting? Voor jy ent moet jy vir jouself die vraag vra, gaan ek die dragtige koeie ent voor kalwing of is dit kalwers wat n vinnige immuniteit moet opbou voor hulle n voerkraal binne gaan? 11 SHEEP FARMERS: How to minimise your losses from Karoo paralysis ticks Jacques van Rensburg Intervet SA (Pty) Ltd. Reg. No. 1991/006580/07 20 Spartan Road Isando 1600 R.S.A Private Bag X2026 Isando 1600 Tel +27 (0) Fax +27 (0) Dit is meestal n probleem in die aanpassings en groeifases (eerste 40 dae) by voerkrale. Hierdie siektekompleks bestaan uit verskeie faktore wat saamwerk om die siekte toestand te veroorsaak. Verliese sluit in n verlaging in gemiddelde daaglikse toename (GDT), verlaging van karkas kwaliteit en dit verhoog die dae op voer (DOV) (1) en beeste wat herstel van longontsteking, se vleis is ook taaier. Watter faktore kan n rol speel in hierdie siektekompleks? Stres Omgewingsfaktore (wye fluktuasie in omgewingstemperature) Swak bestuur Virusse Bakterieë Die rede vir die onderskeid is as volg : Daar is 2 tipes entstowwe wat gebruik kan word, naamlik lewendige entstowwe of dooie entsowwe (geïnaktiveerde entstof) Dooie enstowwe - Moet gebruik word in teel en dragtige diere, asook vir kalfies wat nog suip om voldoende teenliggaam konsentrasie teen hierdie organismes in die kolostrum te verseker. Op hierdie wyse word beskerming aan die kalf van geboorte af verleen mits kalwers genoeg (ongeveer 800 milliliter in vleisbeeste) kwaliteit kolostrum binne 6 ure na geboorte inneem. Gebruik altyd soos aanbeveel deur die vervaardigers. Die eerste toediening met n dooie entsof moet altyd met n skraagdosis, 6 weke later, opgevolg word. >>

2 LUGWEGINFEKSIES IN BEESTE: n Paar vrae beantwoord Lewende entstowwe Moet gebruik word in situasies waar n vinnige immuunreaksie verlang word en van groot belang is. In voerkraal omstandighede vereis ons onmiddelike beskerming omdat die hoë bevolkingsdigtheid en die gevolglike siekteverspreiding dit vereis. Die diere is gestres en n vinnige, doeltreffende immuunreaksie is essensieël omdat beeste aan duisende virusse oor n kort tydperk, uit die omgewing bloodgestel word. Lewende entsowwe behoort verkieslik nie in beeste jonger as 4 maande toegedien word nie. Bied entsowwe 100% beskerming teen siekte toestande? Entsowwe voorkom nie infeksie 100% nie. Wat dit wel doen is om die risiko van die dier te verlaag om besmet te word. Dit verminder ook die hoeveelheid diere wat klinies siek word. Dit verminder ook die hoeveelheid en tyd wat virusse afgeskei word deur die besmette dier. Wat is die redes hoekom entsowwe kan misluk? Genetika van die spesifieke dier. Party diere reageer net beter op entings en sodoende word hulle ten volle beskerm waar ander minimaal reageer en op die ou einde nog steeds siek word. Skraag dosis is nie toegedien nie: Dooie entsowwe verlang n opvolg enting om seker te maak die immuunstelsel is genoegsaam gestimuleer om die dier te beskerm. Baie mense versuim om dit te doen, of gee die opvolgenting hopeloos te laat en sodoende is die dier se immuunstelsel nie genoegsaam gestimuleer nie en word die dier siek. Die dier se voeding en hidrasie status. Ondervoed en gedehidreerde diere reageer minimaal teen entstowwe omdat hulle essensiële vitamienes, minerale en proteïne kort wat noodsaaklik is vir n goeie immuniteitsreaksie. Hantering van die entstof: Lewendige enstowwe kan vernietig word deur enige temperatuur verhoging, ontsmettingsmiddel of deur dit te lank te bêre voor dit weer gebruik word. Die koue ketting moet altyd behoue bly tot die dier ingespuit word. Die entstof moet binne 2 ure na oopmaak gebruik word anders begin die virus gedeelte dood gaan. Die enstowwe wat MSD Animal Health het vir BRD kompleks is: Respiravax Bovitect III Bovitect PI Bovitect P Tipe enstof Geïnaktiveerde (Dooie entstof) Lewende enstof (Modified live (MLV)) Lewende enstof (Modified live (MLV)) Leukotoksien Samestelling BVD, IBR, PI3 en M. haemolytica leukotoksien BVD, IBR en M. haemolytica leukotoksien IBR en M. haemolytica leukotoksien M. haemolytica leukotoksien Positionering (waar om te gebruik) Koei kalf kudde Kalfies na speen; voerkraal. Kalfies na speen; voerkraal. Koei kalf kudde Kalfies na speen; voerkraal. Wanneer om te ent Koeie: 2 maande voor kalwing vir oordra van passiewe immuniteit deur kolostrum aan pas gebore kalf vir beskerming Kalf: van oningeënte koeie kan op enige ouderdom ingeent word. Gebruik as die eerste lewendige entstof (MLV) na speen in vleis bees kuddes op ouderdom 6-8 maande. Gebruik by herimmunisering as eerste enting Bovitect III was in nie dragtige diere. Kan gebruik word saam met ander BRD entings wat nie Mannheimia leukotoksien bevat nie. Registrasie nommers G3867 (Act36/1947) Namibia Reg. V10/24.4/719 G3211 (Act 36/1947) Namibia Reg. V03/24.4/684 G3001 (Act 36/1947) Namibia Reg. V02/24.4/786 G3002 (Act 36/1947) Namibia Reg. V02/24.4/689 Verwysings: 1. Gregg A. Hanzlicek, DVM; Brad J. White, DVM, MS; Derek Mosier, DVM, PhD; David G. Renter, DVM, PhD; David E. Anderson, DVM, MS. Serial evaluation of Physiologic, Pathological and Behavioral changes related to disease progression of experimentally induced Mannheimia haemolytica pneumonia in post weaned calves. AJVR; Vol 71, No3, March Robert M. Chanock; Brain R Murphy; Peter L. Collins; Kathleen V.W. Coelingh; Robert A. Olmsted; Mark H Snyder; Melanie K. Spriggs; Greggory A. Prince; Bernard Moss; Jorge Flores; Mario Gorziglia; Albert Z Kapikian. Live viral vaccines for respiratory and enteric tract diseases. Vaccine; Vol 6; April Amelia R Woolums, DVM, MVSc, PhD, DACVIM, DACVM. Vaccination to control Bovine Respiratory Disease (BRD): Rational and case examples. CVMA Scientific presentations. Beef Respiratory Diseases Rick Hill. BVD vaccine. Centre for epidemiology and Animal Health. Fort Collins (970) Nov /1301 2

3 Why is the energy balance in lactating cows so important? Dr Adél de Haast Most cows go through some periods of negative energy balance during early lactation when feed consumption does not meet demands of milk production. Some important facts Energy balance of any animal is calculated using energy in minus energy out Cows can use energy reserves in early lactation to support milk production Cows return to normal energy balance by 6 to 7 weeks in lactation High producing cows will consume more feed than lower producing cows to meet their energy needs for greater milk production Dry matter intake, not milk yield, is the driving force behind energy balance in early lactation Milk production is not related to body condition score or use of body reserves Most cows go through some periods of negative energy balance during early lactation when feed consumption does not meet demands of milk production. Negative energy balance has been associated with immunosuppression, peri-parturient diseases and increased time to first ovulation and first breeding. NEB (Negative Energy Balance) also reduces the ability of the uterus to recover after calving and may result in persistent inflammatory damage to the uterus which will struggle to carry an embryo. NEB will also affect the quality of the developing egg in the ovary that will be ovulated in the next reproductive cycle. This can lead to an unviable embryo. Cows are selected for higher production and therefore they partition a greater proportion of available energy to milk production rather than other bodily functions. High producing cows mobilize more tissue and are in greater and more prolonged negative energy balance than low producing dairy cows. McGuire et al (2004) showed in a study that cows that gave on average 46.4kg/d, were back in positive energy balance by an average of four weeks following calving. (Figure 1) 15 In the study by McGuire et al, (2004) Body Condition Score (BCS) study, was not well correlated with energy balance. A single BCS gives no indication of whether a cow is gaining or losing weight at that time as body condition scoring is primarily an assessment of subcutaneous tissue change. When a cow begins to replenish mobilized tissue, abdominal fat and intramuscular and abdominal fat are replenished before subcutaneous fat. These fat depots are not evaluated (they are not visible) in the body condition scoring procedure. Without any other practical method of measuring energy balance, body condition scoring is still the most useful tool. Some major metabolic and endocrine changes occur around the time of parturition. The late dry period coincides with the last phase of foetal growth when nutrient requirements for the pregnant uterus increase. A dramatic rise in the demand for glucose, protein and fatty acids for milk synthesis occurs as lactation becomes established. The body will then use NEFA (non-esterified fatty acids) for nutrients. Often fodder flow planning is not at its best and this may result in an exacerbated NEB situation. Animal nutritionist should be involved frequently to assess the quality and nutrient composition of available feed sources. Corrective recommendations and actions that are implemented here may have positive effects on the health of the herd and subsequently profitability too. The general thinking has been that calving interval must be short because short intervals are more profitable. However, if we consider that the main product from dairy cows is milk and that a short calving interval is very difficult without reproductive problems, and that a longer calving interval might be more sensible and also more profitable. References 1. Renate Knop, H. Cernescu, effects of negative energy balance on reproduction in dairy cows, Faculty of veterinary medicine Timisoara, Calea Aradului No. 119, , Timisoara, Romania 2. Mark A. McGuire et al, Controlling Energy Balance in Early Lactation, Department of Animal and Veterinary Science, University of Idaho. Advances in Dairy technology (2004) Volume 16, pg /1301 Energy Balance (Mcal/c) Week of Lactation Figure 1. Energy balance of cows (n =29) in early lactation (McGuire, unpublished data).

4 Sovereign Pour On champion choice Dr Johan Cloete Local trails prove Sovereign Pour On to be the champion choice for the control of roundworms, liver flukes and blue ticks. Roundworms occur more wide spread than liver flukes. (1) In this issue we will focus on our experience with regards to roundworms and liver flukes in South Africa. In very recent trial work conducted in South Africa (1), 80% of the herds in these trials were infested with roundworms, 60% were infested with liver fluke. Blue ticks were also present in low numbers as the trials occurred from March through to October These are the cooler months of the year, with reduced tick numbers on animals. The main focus of the trials was to determine the effect of treating cattle for liver fluke on normal veld conditions with veld parasite exposure and the effect thereof on their bodyweight after treatment. Roundworms were more prevalent than liver flukes, raising the issue that it is probably more important to treat primarily for roundworms and secondarily for liver flukes. This most probably may result in a combination treatment such as Sovereign being the best suited strategic remedy for cases where more than one parasite group e.g. roundworms, immature and mature liver flukes and blue ticks needs to be controlled. Heifers from the Hartebeestfontein region were first checked for the presence of an active liver fluke infestation. Once this was proved the heifers were uniquely identified with the ID tags and placed into the GMPBasic livestock identification and management system. All records of weights and treatments were captured into the system. The heifers were divided into four trial groups, a control group (untreated), a Fluxacur NF group, a Triclabendazole + oxfendazole group and a Sovereign Pour-On group. Young heifers are especially vulnerable to the effects of migrating immature liver flukes if their immune status to Clostridia bacteria is insufficient. This may predispose them to Clostridia infections with possible death and financial losses to the producer. Ensure vaccination for Cl.novyi type B, D and Cl.chauvoei as a precautionary measure to reduce such risks. The heifers were treated with various endoparasiticide products to determine if there was a visible effect of weight gain in the post infestation recovery period. Once the animals had been treated the owners from all the trials (1) were asked to identify the worst appearing animals. The expectation would have been that these animals would have represented mainly the untreated controls. There was no such correlation and the conclusion was therefore that cattle do not show visible symptoms of recovery within one month of treatment. There appears to be a perception amongst some producers and advisors that it is only important to treat cattle with a product that concentrates on liver flukes. In the trials conducted it was found that roundworms were more prevalent at the various trial sites than liver flukes. Adult cows are difficult to assess as they have complicating factors such as suckling calves, autumn to winter weaning and early autumn pregnancy and ensuing poor winter grazing conditions to deal with. The weight losses are as a result of these factors. Winter supplementary feed is absolutely essential to optimise weight gain. In another study, it was found that Rates of growth were significantly reduced by 14.7% and 14.1% in steers receiving a superimposed artificial infection rate of 1200 metacercariae and grazed at 3.54 beasts/ hectare and 4.39 beasts / hectare respectively. Similarly group body weights were depressed 3% and 20% in steers receiving 600 metacercariae and grazed at 3.54 beasts/ hectare and 4.39 beasts/ hectare respectively. There was a significant interaction between level of nutrition and size of artificial infection on body weight changes in the first 12-week period. (2) Treatment advantage In this trial (1) there was a definite advantage to treating an infected herd against liver fluke and roundworm infestations. Products may vary in efficacy from trial to trial. This specific trial indicated that Sovereign was as, or more effective in treating liver fluke and roundworms on a farm with a natural infestation from the pasture. It is important to ensure that the application of Sovereign or the other oral dose remdies is done correctly for optimum efficacy. Roundworms and their effect on pregnancy in heifers In additional trials, Heifers treated for nematode infections were heavier and had higher condition scores (P < 0.01) than untreated control heifers at initiation of breeding, and maintained that difference through pregnancy diagnosis. Liver fluke infection did not affect heifer gains or condition scores prior to palpation (P < 0.01). At palpation, heifers treated for both forms of parasitism had the highest condition scores and weight gains (P < 0.01), and also higher 4

5 pregnancy rates than control heifers and heifers treated for nematodes only (P <0.01). Pregnancy rates for heifers treated for flukes only, were not significantly different from those treated for both nematodes and flukes. Heifers treated for nematodes weaned heavier calves than those not treated for nematodes (P < 0.05). (3) Weight gain The heifers at Hartebeestfontein were infected with 54.2% roundworms and 54.2% liver fluke. The faecal samples indicated an average e.p.g. (egg per gram) of 150 per heifer. These trial heifers responded with positive weight gains (**) over the control group. Control group as base = 0% Flucacur NF = 15.9% (Opposition dewormer) = 14.4% Sovereign = 27.8% (**) Consolidated weight gains over a period of 3 months In the trials conducted in various provinces of the country, it once again became evident that there are distinct differences between various beef breeds and cross-breeds in terms of maintaining their bodyweights under the same conditions in winter. This must be considered when evaluating the post treatment recovery and weight gains expected from your cattle. (1) Calf performance Treatment had a substantial effect on calf weights. Calves from the untreated Group 1 dams were lighter at birth than calves from Group 4 heifers that had been treated for GIN (Gastro-intestinal nematodes) and flukes. Calves from heifers not treated for GIN (Groups 1 and 3) were lighter at weaning than those from heifers that were treated for GIN (Groups 2 and 4). When weights were adjusted for calf age and sex, calves from heifers treated for flukes only (Group 3) were not significantly heavier than calves from untreated Group 1 heifers, nor significantly lighter than calves from Group 2 heifers which were treated for nematodes only. (3) Are you optimising your calf growth? Use the MSD production enhancement program to assist you to achieve optimum production. Sovereign - convenience & efficacy Sovereign is a Pour-On formulation which has been specifically formulated in such a manner as to afford the absorption of the majority of the active ingredients through the skin of the animal. It is not impossible for a small percentage of it to be absorbed via the grooming process. In the winter it is recommended not to apply the product when the ambient temperature is at minus 1 degrees celcius or lower. This may decrease absorption and no efficacy. The product formulation is very volatile (evaporation effect) and hence it is important to apply the product in a short but highly concentrated manner on the skin to reduce evaporation and to increase transdermal absorption. The dosage should be applied at 1ml/10kg live body mass. Cows, oxen or bulls exceeding 650 kg should receive an additional 5ml for effective absorption. Reference: 1. MSD field trials conducted by Dr JD Cloete (BVSc), faecal and serology work by MRU, Malelane Approved for publication by the Director of the Louisiana Agricultural Experiment Station as manuscript number * Corresponding author. Fax: address: aloyacano@agctr.lsu.edu (A.F. Loyacano) /02/$ see front matter 2002 Elsevier Science B.V. All rights reserved. PII:S (02) F. Loyacano et al. / Veterinary Parasitology 107 (2002) A. 133/1301 Reg. No. G3831 (Act 36/1947) 2013 ISSUE 2 5

6 ZOONOSeS Dr Mats Abatzidis MSD Animal Health would like to take this opportunity to inform you, the reader, regarding the importance of gaining knowledge on zoonotic (diseases that can be transferred from animals to humans) diseases. These diseases will be dealt with in alphabetical order. ANTHRAX Synonyms: Charbon, Malignant pustule, Malignant carbuncle, Milzbrand, Splenic fever, Woolsorters disease Classification: Direct Zoonosis Distribution: Anthrax has an almost world-wide distribution AGENT DETERMINANTS Bacillus anthracis: aerobic, endospore-forming, Gram-positive rod. Sporulation does NOT occur in an unopened carcase. The capsule, size and shape of the organism are of diagnostic significance. Encapsulated forms are invasive i.e. resistant to the immune system of the host and highly virulent. No capsule, no disease. The most important determinant of disease with respect to the agent is therefore the anthrax spore. It is resistant to physical inactivation by enviromental heat, cold and desiccation and highly resistant to chemical inactivation with disinfectants. Fortunately B. anthracis is not a saprophyte (feeds on dead organic matter) in nature and it cannot easily perpetuate itself in competition with saprophytes. B. anthracis produces a toxin of THREE components oedema factor (EF): protective antigen (PA): lethal factor (LF): Factor I Factor II Factor III HOST DETERMINANTS All mammals appear to be susceptible and generally speaking, cattle, sheep, horses and goats, in that order, are the most susceptible and commonly affected animals. Pigs, dogs and cats are ± equally resistant and man lies somewhere in between. The disease is however primarily a disease of herbivores. Epidemic trend: (General Mode of Spread) - dissemination throughout a susceptible population by way of a common source of exposure to a viable spore population. In LIVESTOCK The soil is seeded with anthrax spores in an epizootic form in late summer during dry, hot and windy conditions (NB. seasonal). Vegetative bacteria contaminate the soil via bloody fluids which exuded through the natural openings of animals that have died of anthrax. Persistence in soil appears to be aided by: An alkaline ph (6,0+) Adequate moisture Temperatures in excess of 15.5 o C Reduced micro-organism antagonism Infection occurs via inhalation, ingestion, or contamination of skin lesions. Predators and mechanical vectors may play a role in the spread. Other important sources are infected feed, or bone meal used as a fertilizer (man & animals). The most common cycle of transmission is: soil-borne organisms susceptible herbivore host disease death dissemination of organisms from the carcase to other premises. ENVIRONMENTAL DETERMINANTS In MAN Industrial anthrax: Seen in persons engaged in processing animals or animal by-products that may be contaminated due to the animal dying of anthrax Agricultural anthrax: Seen in persons contacting the infected animal in the field - usually cutaneous form. SYMPTOMS Animals Peracute Acute Subacute to chronic Ruminants Horses Dogs, cats and pigs 6

7 ANTHRAX Man There are THREE major forms depending on the mode of entry and location of the site of infection: 1) Cutaneous anthrax 2) Inhalation (respiratory) anthrax 3) Intestinal anthrax All three can be complicated by meningitis and septicaemia In man, the disease usually occurs in the cutaneous form (95%) with 80% of victims recovering without treatment. 1) Cutaneous anthrax: 95-98% of human cases are contracted via a cut or abrasion and NOT due to penetration of intact skin. Incubation: 1-7 days The lesions appear in the following sequence: Papule (pruritic/itchy): vesicle (fluid clear then dark & bluish-black) rupture with necrosis - black eschar = relatively painless with mild systemic symptoms = pyrexia/fever, inflamed and swollen lymph nodes healing with black scab falling o f f granulation distinct scar: The head and forearm are the most common sites of lesions followed by the hands. Sometimes (20%) this form of the disease progresses into a fatal septicaemia/toxaemia (bacteria and toxins spread throughout a host s blood circulation). 2) Inhalation (respiratory) anthrax: How it happens: viable spores enter the lungs via inhalation where they are consumed b y im mune c ells and transported to the mediastinal lymph nodes. Toxin is released and the disease progresses rapidly to a fatal toxaemia and bacteraemia (bacteria circulating within host s blood circulation). Lymph nodes are necrotic (die off), haemorrhagic and oedematous (swollen). Incubation period: 6-10 days Clinical signs: Phase 1: mild upper respiratory tract infection which can be confused with influenza (flu), viral respiratory disease and mild bronchopneumonia Phase 2: Acute dyspnoea (battling to breathe), cyanosis (blue discolouration of the mucous membranes), diaphoresis (profuse sweating), accelerated pulse and breathing rate, stridor, rales & signs of pleural effusion, rapidly fatal. 3) Intestinal anthrax: How it happens: The bacteria usually enter by ingestion of contaminated tissues of animals that have died of anthrax. Infectious organisms penetrate the intestinal lining of the terminal ileum or caecum. Toxin is released in the tissue immediately below the lining of the intestine and ulcers develop due to the necrotizing (dying off) effect of the toxin. The ulcers can also result in haemorrhage. Incubation: 2-5 days Clinical signs: nausea, vomiting, anorexia and fever with abdominal pain. Which may progress to toxaemia, shock, cyanosis and death. Mortality rate is 20-50%. NB: Meningeal involvement results in a ±100% mortality rate and may develop as a primary or secondary lesion, often as an extension to cutaneous anthrax in the latter case. Differential diagnosis: Many other diseases can give a clinical picture similar to that of anthrax, namely, rapid bloating, incomplete rigor and bloody exudates from natural body openings. These include: Clostridial diseases Heavy metal poisoning Certain toxic plants Bloat Ketosis Lightning PREVENTION AND CONTROL Anthrax is a controlled animal disease i.e. authorities should be informed of its incidence Animals: vaccination. Humans: a vaccine has been used successfully in at risk individuals (wool & hide processing) To minimise spread, do NOT perform a post mortem (PM) and adequately dispose of carcasses by either incineration or deep burial with quicklime (anhydrous calcium oxide). 136/ ISSUE 2 7

8 hoekom beeste dip in die koue wintermaande? Me Elize Terblanche & Dr Johan Cloete Hoekom dip ons as ons nie bosluise sien nie? Dit is n relevante vraag wat menige kritiese lesers sal vra as hulle die titel van hierdie artikel onder oë kry. Ons verduidelik: Gedurende die lente en somer maande dip ons gewoonlik om bosluisgetalle te verminder en dan ook om siektes soos rooiwater en galsiekte te voorkom. Afrika rooiwater word oorgedra deur twee bosluise, naamlik Rhiphicephalus microplus en Rhiphicephalus evertsi evertsi. Asiatiese rooiwater word oorgedra deur die bloubosluis, naamlik Rhiphicephalus decoloratus. Rhiphicephalus microplus en Rhiphicephalus decoloratus is albei een-gasheer bosluise. Wanneer dit by die voorkoming van meergasheer bosluise kom is dit moeiliker om bosluise hok te slaan as gevolg van die volgende redes (1) : a. Hulle lewenssiklus is lank (5 maande tot >1 jaar vir die bontbosluis), en b. Nimfe kan vir 2-3 maande weg van die bees af oorleef c. Dip besluite word gebasseer op die teenwoordigheid van volgesuigde volwasse wyfies in die somer, en neem nie die groot getalle onvolwassenes in ag wat tydens die kouer winter maande op beeste voorkom nie. Van die meer-gasheerbosluise wat die meeste probleme in beeste veroorsaak is: Drie-gasheer bosluise (1) Bontbosluis (Amblyomma habraeum): Hartwater en absesse veral uier- en skede-absesse in die somermaande Bruinoorbosluis (Rhipicephalus appendiculatus): Oor-absesse word deur die volwassenes veroorsaak met n piek tydens Januarie tot Maart. Simptomatiese behandeling is reaktief, duur en nie altyd bevredigend nie. Twee-gasheer bosluise (1) Bontpootbosluis (Hyalomma spp.) : Weefsel-afsterwe (nekrose) by die bytplek en sweetsiekte. Behandeling van kliniese gevalle is ook reaktief en duur. Rooipootbosluis (Rhiphicephalus evertsi evertsi): Afrika rooiwater met pieke in die herfseisoen. Wanneer n dipmiddel aangewend word, word net die bosluise (bykans onsigbare onvolwassenes en sigbare volwassenes) op die beeste geaffekteer. Die stadia wat nie tydens behandeling op die bees voorkom nie, kom ongedeerd daarvan af en sal by n latere geleentheid op die bees klim - wat weer latere herdipping noodsaak. Vir koste-effektiewe dipping is dit dus nodig dat ons die lewenssiklus van die drie-gasheer bosluis oor n seisoen heen verstaan. As hartwater naїewe beeste in die laat-winter en/ of lente op gespaarde kampe wei is dit moontlik om gevalle te kry wat deur nimfe oorgedra word sonder die teenwoordigheid van enige volwasse bosluise. THREE-HOST TICK LIFECYCLE / DRIE-GASHEER BOSLUIS LEWENSIKLUS Larvae/Larwes BONT TICK, BROWN EAR TICK AND KAROO PARALYSIS TICK BONTBOSLUIS, BRUINOOR BOSLUIS EN KAROOVERLAMMINGSBOSLUIS Adults/Volwassenes Nymphae/Nimfe Engorged Larvae/ Volgesuigde Larwes Engorged Nymphae/ Volgesuigde Nimfe Larvae/Larwes Eggs/Eiers Engorged Female/ Volgesuigde Wyfie 8

9 Bosluise gaan nie dood tydens die koue wintermaande nie. Koue affekteer nie die eiers wat deur volgesuigde wyfies tydens die laatsomer gelê is nie. Die uitbroei van eiers word wel later vertraag deur die kouer weer. Figuur 1 toon aan dat die drie-gasheerbosluis se lewenssiklus verbreek kan word indien dipping gereeld in die winter toegepas word. Drie-gasheerbosluise het n baie langer lewenssiklus (5 maande tot langer as een jaar) as die van een-gasheerbloubosluise (56 dae onder ideale toestande). Hulle onvolwassenes, wat onsigbaar is, kom in groot getalle tydens die wintermaande op beeste en ander tussengashere soos tarentale, hase en skilpaaie voor Volwassenes Larwes Nimfe Jan Feb Mrt April Mei Jun Jul Aug Sep Okt Nov Des Figuur 1: Seisoenale voorkoms van drie-gasheerbosluisgetalle op beeste Variasies afhangende van streek sal voorkom (2) Om die uitdaging van meer-gasheer bosluise in die somer te beperk is dit aangewese dat, na dipping in die winter, beeste vir die tydperk wat die dip aktief op die bees is (gewoonlik 3-10 dae met olie basis opgietmiddels afhangende van reënval, haarlengtes graslengte ensovoorts), en deur die meeste kampe te roteer na elke behandeling sodat enige bosluise wat op die weiding wag vir beeste, kan opklim en deur die residuele werking van die dip gedood kan word. Dit sal die bosluislas en die gepaardgaande probleme, in die somer help beperk. Van MSD Animal Health se dipprodukte, almal doeltreffend teen vatbare drie-gasheer bosluise, is die volgende: - Taktic Cattle Spray (Reg. no. G2535 Wet 36/ 1947) spreidip vir totale benatting met swaar bosluisladings: verdun 1 liter dip met 500 liter water vir beeste Delete All (Reg.no. G2837 Wet 36/ 1947) opgiet dip: 1ml per 10kg gewig oor die toplyn van kop tot stert Delete (Reg no. G2815 Wet 36/ 1947) opgiet dip: 1ml per 10kg gewig oor die toplyn van kop tot stert Delete X5 (Reg no. G3279 Wet 36/1947) spreidip. Vir bosluise: Los 500ml op in 500 liter water Deltab Tablets (Reg no. G2517 Wet 36/ 1947): 1 x 25.0 gram tablet per 100 liter water Deltab Back-Pack (Reg no. G2518 Wet 36/ 1947): 1 x 2.5 gram tablet per 12.5 liter water genoeg om een volwasse bees volledig, doeltreffend te benat n Winter dipping is dus nooit vergesog nie en behoort oordeelkundig aangewend te word tesame met n goeddeurdagte weidingrotasie strategie. Die voordele van minder uierkwartskade, absesse, verliese as gevolg van hartwater en bruinoorbosluis maak dit die moeite werd. Verwysings 1. Coetzer J.A.W. en Tustin R.C. (ed) 2004 Infectious Diseases of Livestock. 2 nd edn. Oxford Univ Press. 2. Horak I. University of Pretoria student notes 3. Jan du Preez en Faffa Malan, Entstowwe en immunisering van plaasdiere. 135/1301 G2837 (Wet 36/ 1947) G2518 (Wet 36/1947) G2517 (Wet 36/1947) G2815 (Wet 36/1947) G3279 (Wet 36/1947) 2013 ISSUE 12 9

10 Sheep farmers How to minimise your losses from Karoo Paralysis Ticks (Ixodes rubicundus) Jacques van Rensburg Ticks are generally found in the warmer parts of South Africa with exceptions of the blue- and red- legged ticks that may be present in a much wider distribution area. There are other tick species that will be more of a challenge in the winter months like the Karoo paralysis tick (Ixodes rubicundus) 4. Ticks General Ticks are obligate external parasites of most types of vertebrates (animals with a backbone) virtually wherever these animals are found. Ticks belong to the class Arachnida, members of the subclass Acari and are therefore more closely related to spiders than to insects 2. Ticks have four developmental stages: egg, larva, nymph, and adult. Between every stage the tick will undergo a moulting process where they will lose the outer layer or skin before developing into the next life cycle stage. Once the adult female tick has mated with an adult male she will fall from her host and begin to lay eggs in the environment. One of the key differences between the larvae, nymphs and adults is that the larvae only have 6 legs, while the nymphs and adults have 8 legs. Adult ticks also have a distinctive genital and anal area on the ventral body surface that could be used to identify the correct sex of the tick at an early stage of development. The forelegs of all ticks bear a unique sensory apparatus called the Haller s organ, used for sensing carbon dioxide, chemical stimuli (odour), temperature, humidity etc. and is one of the effective ways that ticks use to locate accessible hosts in close proximity. Pheromones are used to stimulate group assembly, species recognition, mating, and host selection 2. Certain tick species can survive several months and occasionally a few years, without food if environmental conditions permit. Tick host preferences are usually limited to a certain genus, family, or order of vertebrates; however, certain ticks are exceptionally adaptable to a variety of hosts. The larvae and nymphs of most ixodids that parasitize livestock, feed on small wildlife such as birds, rodents, small carnivores, or even lizards 2. Ticks are mainly divided into 3 main groups according to their developmental habits 4 : 1. One-host ticks: These ticks complete all of their developmental stages (larvae, nymphs and adults) on the same host. (e.g. Blue tick Boophilus decoloratus and B. microplus) 2. Two-host ticks: Ticks of which the larva and nymph will stay on the same host. The fully engorged female nymph will fall from the host and moult into an adult female that needs to climb onto a second host in order to develop further (e.g. Red-legged tick Rhipicephalus evertsi evertsi). 3. Three-host ticks: Ticks in this group will, when fully engorged, fall from their host and moult into the next stage after which they will again climb onto the next available host thus potentially feeding on three separate hosts (e.g. Karoo paralysis tick - Ixodes rubicundus). Karoo Paralysis Tick (Ixodes rubicundus) The female paralysis tick is quite small in size and almost black in colour before they take their first blood meal. Once they have started feeding their colour will change to a more orange/reddish brown colour (hence the species name rubicundus). When fully engorged the female will present herself as a shiny dark brown tick. The male tick stays a shiny dark brown colour 5. Distribution: The distribution of the Karoo paralysis tick is associated with the presence of besembos (Rhus erosa) and suurpol grass, which tends to harbour these types of ticks as well as their intermediate hosts 1. Ixodes rubicundus occurs in the Karoo, eastern parts of the Western Cape Province, Eastern Cape Province, southern parts of the Free State Province and isolated patches in the Gauteng and Mpumalanga Provinces of South Africa 1. The natural hosts of the adults are caracal (lynx) and mountain reedbuck, but they also readily infest sheep, goats, cattle and even dogs on occasion 1. The tick is typically found in hilly or mountainous terrain associated with habitats which also favour the species of shrews and hares on which the larvae and nymphs feed 1. The adult and immature stages of this tick are active and most abundant from autumn through to spring. They also prefer the southern slopes of hills which are cooler than the northern slopes. Both the eggs and engorged nymphs of one season have their development arrested during the summer months and only resume their further development (hatching or moulting to adults) in the following late summer or autumn, usually after a cold spell of weather. Immature stages may parasitize the rock hare, other hares, and elephant shrews. The life cycle thus takes approximately two years to complete. Seasonality The active period for adult ticks begins usually late in summer and reaches peak levels in autumn and early winter (April/May) and declines 10

11 thereafter. Towards the end of September only a few adults may be found on livestock 5. The paralysis commonly occurs from February and reaches a peak in April and May. Sudden drops in temperature caused by rain, cold winds and cloudy conditions seem to stimulate the activity of the adult ticks 5. A female tick can lay up to eggs when she drops from her host. The egg-laying period normally takes place from the end of August or early September and eggs may take months to hatch. When hatched, the larvae will feed during the autumn of the following year and may take up to 2 months to develop and moult into a nymph. The nymphs will develop and feed during the next spring to develop and moult into adults after approximately 6 months 5. Adult ticks are most active during late summer (as early as February), peaking in the autumn and early winter after which their activity will gradually decrease 5. Symptoms The adult tick excretes salivary toxins that cause paralysis in sheep, goats, humans, dogs and jackals (calves and some antelope species may also be affected). Only some ticks will be the carrier of the toxins 4. Interestingly, only 0.64 to 3.56 ticks per bodyweight (sheep) is needed to induce paralysis; however, all ticks need to be removed in order to stop further development of the paralysis 5. Affected animals become paralysed and some may even show signs of incoordination and stumbling. The host animals need to be exposed to a certain amount of toxin to show signs of paralysis and subsequently variable degrees of paralysis may occur. Some animals may be completely paralysed while others may only show slight signs of weakness, like stumbling of the hind legs when chased. If the toxins are still in the early stages of paralysis, simply removing these ticks will help the animal recover quite rapidly. Unless these ticks are removed, the animal will remain paralysed and will die within days. Angora goats (especially young goats) and Dorper sheep are particularly susceptible to paralysis and great losses can be incurred if animals are not dipped early enough. The latter two animals have similar eating habits, putting them in closer contact to these ticks 5. Huge losses have been recorded due to tick paralysis in the past when animals were not seen and treated in time. In 1951, approximately sheep died due to paralysis within 3 areas of the Karoo and it was also found, more recently, that up to 15% of animals that are not treated can die from paralysis 5. The preferred attachment sites of these ticks are mainly on the legs (seldom lower than the knee) and along the lower line of the neck, chest and belly. In the case of wool sheep they do prefer the wool-less areas around the groin area and under the armpits, however, it is also common to find these ticks between the shoulders in the wool. The latter is quite different to many other tick species that very seldom or never target the wool areas on wool sheep. It is particularly difficult to see these ticks in the wool and may only present themselves as small black spots. When a tick is seen one should try to preserve it in methylated spirits in order to assist with the identification and so the confirmation of the tick species present on your farm 5. Prevention and Control Most affected animals recover within 24 to 48 hours, once the ticks have been removed or animals have been dipped. Losses may be greatly reduced when animals are dipped with a dip containing the active Amitraz. Amitraz is developed to paralyse the mouthparts of the tick thus ensuring the release of the tick from the host shortly after treatment (dipping). Thus, the tick will be unable to attach to any new host and will die as a result of starvation. An example of such a product is Taktic Cattle Spray. Care should be taken when sheep with long wool are dipped to include Zink sulphate to assist in the prevention of wool rot 5. The following prevention guidelines are recommended: If possible, remove susceptible animals from February from especially mountainous sheep camps that have a southerly aspect. Camps containing suurpol and besembos which are historically known to predispose sheep to paralysis should also be considered 5. When these camps have to be used one should consider starting to dip as early as February and continue to dip with regular intervals (1-3 weeks apart). One could use a few goats as a tick indicator to see when the tick population is on the increase. Dip animals strategically before the potential outbreak periods. Dips generally have longer residual effect on sheep with wool compared to sheep with no wool. Remember that rainwater can affect the duration of efficacy of dips. Cattle and Boer goats may be used to clean-out infested camps like vacuum cleaners before dipping them with an Amitrazcontaining product like TAktic Cattle Spray; particularly helpful where game farmers have problems with tick paralysis. Is has also been found to be beneficial to have cattle and horses go into the camp first and only let the sheep into the camp once the grass is much shorter 5. MSD Animal Health supplies the following dips that can be used against Karoo paralysis tick: Zipdip Taktic Cattle Spray The following pour-on formulations may also be used: Delete Delete All Bottom of Form With the use of pour-on formulations it is recommended to only apply these products on the wool-less areas and not directly onto the wool as this practice could lead to discolouration of the wool Product information: Zipdip Contains: Triazophos 40% m/m (Reg. No. G381 Act 36/1947), Taktic Cattle Spray Contains: Amitraz 12,5% m/v (Reg. No. G2535 Act 36/1947), Delete Contains: Deltamethrin 0,5% m/v and Piperonyl butoxide 2% m/v (Reg. No. G2815 Act 36/1947), Delete All Contains: Amitraz 2% m/v, Deltamethrin 0,5% m/v and Piperonyl butoxide 2% m/v (Reg. No. G2837 Act 36/1947). References: 1. MSD web page New/Informative Articles/996. aspx#0 -Karoo Paralysis Tick Tick Paralysis: Introduction Ixodes spp 4. Mönnig en Veldman Handboek oor veesietes p Vra vir Faffa: Article written by Dr. Faffa Malan, Intervet - n deel van Schering- Plough en Prof. Gareth Bath, Fakulteit Veeartsenykunde, Universiteit van Pretoria 134/ ISSUE 2 11

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