Recent Spread of Tuberculosis in the Kapiti and Horowhenua Districts

Recent spread of tuberculosis in the Kapiti and Horowhenua districts

The Kapiti, Horowhenua and Manawatu dis- proximity to Wellington, there are many Tuberculosis breakdowns tricts have traditionally been free of bovine subdivisions of small farming or lifestyle tuberculosis. lnvestigations of tuberculosis blocks whose owners commute to the The breakdowns that occurred are breakdowns before 1990 showed that the in- capital. Horticultural blocks, with accom- shown in Table I. fection couldgenerally be traced to cattle that panying shelter belts, are scattered be- Otaki Beach: In early 1992, a large had movedfrom tuberculosis endemic areas. tween the livestock farms as the climate town-supply dairy herd just north of the Most breakdowns in cattle herds involved is suitable for many enterprises such as Otaki River (Property A, see Table I) was only a single infected animal. Since 1990, pip and stone fruit. Generally the owners tuberculin tested following the finding outbreaks ofbovine tuberculosis have occurred of smaller 'lifestyle' blocks farm a few of a tuberculous lesion in a bull beef in herds in the Horowhenua and Kapiti Dis- cattle, sheep or horses and the properties animal at slaughter in December 1991. tricts. At the time of these breakdowns there change hands frequently. Thus stock and Investigations revealed no obvious source was no immediate obvious domestic animal human movement is commonplace and of infection. The whole herd test resulted source of infection so a tuberculous wildlife part of the farming culture. in 12 reactors, eight of which had visible source was considered. Subsequent surveys Before 1992, the endemic area to the lesions at slaughter. of wildlife showed that tuberculosis was south,(')included the area around Moon- As usual in this district, there had present in theferret and cat population in the shine Valley and Pauatahanui (Figure 1). been many stock movements from the Otaki Beach area, and in the ferret and pos- This boundary was drawn after persist- herd since the previous whole herd test. sum population around the Manakau town- ent infections in small herds around these Heifershad been grazed at Te Horo Beach ship. localities in the 1970s and the finding of and animals had been bought. However, The Kapiti Coast and Horowhenua tuberculosis in possums, wild deer and investigation of all the source and in- districts of the lower North Island are pigs in 1980. contact herds and immediate testing on intensively farmed areas and extend from However, in 1991 there were several many of these herds revealed no obvious Paraparaumu north to the town of Fox- breakdowns inbeef cattle and dairy herds source of the infection. ton and from the coast eastward to the in the Paekakariki Hill and McKay's Testing of all neighbouring herds re- Tararua mountain ranges. On the eastern Crossing areas that led MAF Quality vealed only one tuberculous animal, a side of these ranges is the Wairarapa, Management (MQM) staff to believe that 15-month beef heifer on Property B. which has been known to be an endemic the feral animals inhabiting the bush this There had been no direct contact be- area for bovine tuberculosis since the far north were infected with bovine tu- tween infected groups on Properties A 1970s, with wild animals such as pos- berculosis. So in 1992 the northern Wel- and B but the infected animals had at sums and red deer infected. lington endemic boundary was redrawn some stage grazed the paddocks adja- The vegetation in the Kapiti and to cross from the coast to the ranges at cent to the beach. High on the list of risk Horowhenua districts is mainly grass Paraparaumu. At the time the placement factors was a feral animal source, so a with some lupin and a few remaining of a tuberculosis 'buffer', in which feral survey was undertaken of possums, fer- boxthorn and pampas bushes on the animal control would be ongoing, was rets and feral cats. coastal sand dunes. There are several raised.") Further information was re- In the area in which the cattle had inland lakes and swamps that supply quired before an effective 'buffer' could grazed, possums were in fairly low num- cover for wild mammalian and bird life. be put in place. Therefore all stock north bers (0.26 possums per hectare) as the Rabbits are controlled regularly as they to the Otaki River, the northern bounda- land supported little of their habitat. Fer- are in abundance, particularly in the coast- ry of the 'fringe' zone,(')were put on to an ret and cat numbers were estimated to be al areas. annual tuberculin testing program. high because of the large numbers of Dairy farms are scattered throughout the area and many are on a winter milk (town) supply contract. Beef breeding and beef finishing make up a significant proportion of the farms. Because of the

25 0 25 50 75 100 Kibmetas

Figure 1: Map ofthe south eastern North lsland of New Zealand 18 Surveillance 23(2) 7996 rabbits and birds in the open sand dune Table I: Herds affected with tuberculosis in the Kapiti and Horowhenua districts country and around the lakes and swamps. In the first weekof the survey, a tuber- Date Location Property Herd First Reactors1 M. bovis REA Comments culous ferret was found on the property Type detected No.Tested isolated Type adjacent to Property A. About this time Dec Otaki A Dairy Slaughter 121415 8 W.CP Skin Tb bovine tuberculosis was found in ferrets 1991 Beach also present in the Mackenzie Basin of the South Is- land, on and around properties on which Feb Otaki B Dairy & Testing 11412 1 W.CP bovine tuberculosis was present in the 1992 Beach Beef farmed livestock. (2) The survey contin- Mar Otaki C Dairy Testing 31224 3 Pending ued for several months and moved fur- 1994 Beach ther inland but no evidence of tuberculosis was found in the more than 600 pos- May Otaki D Dairy Testing 31482 1 Pending sums examined. 1994 Beach In July 1992, a cat shot in the northern part of the survey area, towards Waikawa APr Pukehou E Beef Testing 2178 2 W.CP Beach, was found to have extensive tu- 1993 Breeding berculous lesions. Although the disease May Pukehou F Deer Testing 191812 1 W.CP Avian had not been found in possums, possum 1993 reactivity in control was instituted on the assumption herd that possums, the traditional tuberculosis vector, could be the primary source of Jun Te Horo G Dairy Testing 91394 1 Skin Tb the disease in the other ~pecies.(~)[~)Apart 1990 Beach also present from the ferrets and cats trapped and Dec Te Horo H Dairy Testing 61246 2 W.CP Skin Tb caught at the time of the survey, no fol- 1992 Beach also present low up control has been directed towards ferrets and cats. Aug Te Horo I Dairy Testing 121220 1 Skin Tb The Otaki Beach and Waikawa Beach 1992 Beach also present areas have now been under intensive Nov Te Horo 3 Beef Testing 11103 1 W Animal possum control for two years (see Figure 1993 Beach Breeding bought in 2) and possum numbers in the areas have continued to diminish (1993/94 counts Mar Te Horo K Deer Slaughter Pending 4 Pending 0.134 possums per ha). In March and I994 Beach May 1994 two more dairy herds were placed on Movement Control when tu- Jun Manakau L Beef Slaughter 0117 1 Pending 1993 Drystock berculin test reactors with tuberculous lesions were detected at the annual test. Oct Manakau M Beef Testing 3/25 2 W.CP Both herds are neighbours of the original 1993 Drystock severely infected herd, and the disease had not been detected previously in these Nov Manakau N Dairy Testing 321304 19 W.CP Within herd herds (Properties C and D). 1993 infection also feral source Pukehou: In February 1993, a ferret handed to the Levin Livestock Officer Nov Manakau 0 Beef Testing 1/74 1 W.CP (LO) by a farmer was found to have a 1993 tuberculosis-like lesion in the prescapu- lar lymph node. The ferret had been Jun Manakau P Dairy Testing 6/56 5 Pending picked up on the main road at Pukehou, 1994 near the Forest Lakes turn off, in Novem- Jul Manakau Q Dairy Testing 11252 1 Pending ber 1992, placed in a deep freeze and 1994 retrieved when the LO visited the farm. Histological examination showed lesions Jul Manakau R Dairy Testing 3/21 1 1 Pending consistent with bovine tuberculosis but 1994 Mycobacterium bovis was not cultured. Ma Koputaroa S Beef Testing 2110 12 Pending All animals About a month later at the routine 1976 Breed & with lesions tuberculin test on two nearby farms on to Dry stock bought in the western side of Highway 1, several Mar 1991 reactors were detected and lesions were found at slaughter. They included an Dec Koputaroa T Beef Slaughter 01357 1 Pending aged hind from a nearby deer herd, and 1990 Breeding two bovine weaners in an adjacent small Dec Koputaroa U Deer Slaughter 711012 3 Pending Owner buys beef breeding herd (Properties E and F). I990 in and M. bovis was cultured from the lesions finishes stock from all three animals. Neither herd had a history of the disease, and both had Mar Waitarere V Dairy Testing 11142 1 W.Wait been tested a year previously. These facts, 1992 together with the finding of the tubercu- Jul Waitarere W Beef Testing 1/38 1 W.Wait lous ferret only about 1 kilometer away, 1992 Breeding again indicated that feral animals were a likely source of the infection. Jun Koputaroa X Beef Testing 21383 1 W.Koput TeHoro Beach: In 1YY2, bovine tuber- 1993 Breeding culosis was detected in two large neighbouring dairy herds in the Te Horo Beach Mar Koputaroa Y Beef Slaughter 1I540 1 CNI 1994 Drystock area, south of the Otaki river (Properties H and I). One herd had two tuberculous Apr Ihakara Z Dairy Testing 11455 1 Pending reactors and the other had a single tuber- 1994 culousreactor. M. bozjis was cultured from Surveillance 23(2) 7 996 19 all lesions. These breakdowns followed a positive animal detected in another neighbouring dairy herd in mid 1990 (Property G). In spring 1993, another beef herd, which had recently been formed on the Te Horo beach country (Property J), also had a tuberculous reactor at its first test. However, this reactor could have originated from a herd from the Wellington area with a history of tuberculosis. In early 1994, three hinds from a new deer herd established on an old horticultural block immediatelysouth of the Otaki river (Property K) showed tuberculous lesions at slaughter. M. bovis was cultured from the lesions. The herd had been assembled from several sources, although the owner claimed that the positive hinds were from accredited tuberculosis-free herds. Non-specific tuberculin reactivity: Dairy cows in the Otaki Beach and the Te Horo Beach areas have a skin tuberculo- YI sis problem, which causes non-specific 12 0 2 4 6 8 1OKibmacre reactivity to bovine tuberculin. In many cases skin tuberculosis is evident visual- ly. This skin infection, caused by Myco- Figure 2: Map showing possum control operations and location of tuberculousferal animals in Kapiti bacteria that have never been cultured or and Horowhenua districts identified, appears to be antigenically closer to bovine than to avian tuberculin. Three possums found on the northern Waitarere Beach area (Properties V and The phenomenon has been recognised in and eastern end of the survey area, and W) had single reactors at the routine tu- dairy cows in the Kapiti I Horowhenua one ferret found on the southern end, berculin test. Both had bovine tuberculo- districts since the 1950s. had tuberculous lesions from which M. sis lesions at slaughter. Again there was Many cows have been slaughtered bovis was cultured. After these findings a no obvious explanation as to how these because they reacted to the skin test but possum contol operation was undertak- herds became infected. Both herds were were in fact not actually infected withM. en around the Manakau township as high- ’closed and both had a clean history. The bovis. However, on Property A some cows lighted in Figure 2. land on which these herds were located infected with bovine tuberculosis also Koputarod Waitarere: This area lies fell outside the BLIP area. had evidence of skin tuberculosis. Thus a at the northern end of the Horowhenua A subsequent predator survey car- mixed infection can occur in the one herd district immediately south of the Mana- and in the one animal. ried out by Landcare Research in 1993 watu river. Waitarere Beach is adjacent failed to find any tuberculous ferrets, Manakau breakdown: In mid 1993 to a large commercial pine forest. Pos- feral cats or possums (in more than 60 bovine tuberculosis was detected in two sums, ferrets and cats are prevalent, and possums examined).‘‘) small beef finishing herds in the Mana- a herd of wild Sambar deer roams the kau district (Properties L and M). A large area. The Koputaroa area is an intensive- Later in 1993 another ’closed’ cattle dairy herd on the northern boundary of ly farmed dairy and beef area, requiring herd in Koputaroa was found to have a these infected herds was immediately drainage as it is low lying, but fertile and tuberculin test reactor, which was posi- tuberculin tested (Property N). Of the productive. Most herds in the area were tive for the disease at slaughter (Property 304 dairy animals tested 32 reacted and historically accredited or free of bovine X). This herd was just to the east of the many showedbovine tuberculosislesions tuberculosis. However, before 1990 one designated BLIP area, but bordered onto at slaughter. The test took place in No- large beef breeding and dry stock herd, the river country with its areas of cover. vember 1993 and the herd had previous- which bought in most of its finishing In February 1994 M. bovis was isolated ly tested clear in July 1992. stock from saleyards in the area, had a from a bull in a dry stock herd, again at Details of the spread of bovine tuber- persistent bovine tuberculosis problem slaughter. In this case, because of this farmer’s buying policy, the animal could culosis in this herd and in other herds in (Property S). This herd bordered on the the Manakau district will be outlined in a southern end of the Manawatu river have come on to the property with the disease (Property Y). later publication. where flax cover for possums is in abun- During the following months four dance. It was generally assumed that the Ihakara: Because of the increasing moreherds in theManakau area (Proper- infection was ’bought in’ because of the tuberculosis problem in the Horowhen- ties 0, P, Q and R) had reactors, which farmer’s buying policy. However, in late ua district, MQM and Regional Animal subsequently showed bovine tuberculo- 1990 a heifer in a neighbouring herd Health Committee representatives met sis lesions at slaughter. Results of culture (Property T), which had always been ac- in late 1993 and decided to test the whole on the lesions from the two most recently credited for tuberculosis, was found to area annually. Herds north to the Mana- detected cases is still pending. Stock be infected at slaughter. Also in 1990 a watu River and east to the ranges through movements could not account for the neighbouring deer herd (Property U) had to the township of Shannon were includ- infection and there was minimal direct infected stock at slaughter. Many of these ed. The area was named the Special Tu- contact between herds.i5) animals were bought in and their origin berculosis Investigation Area - Horow- was impossible to trace. All farmers interviewed at the time of henua.i7) their breakdowns independently com- As a result of these findings a brief In April 1994 a dairy herd in the Ihaka- mented that they had recently noticed a localised immediate possum poisoning ra district, east of Koputaroa toward the dramatic increase in possum numbers operation (BLIP) was carried out in the Tararuas, was tested and had one reactor compared to previous years. A feral ani- Koputaroa area, and repeated in 1992. out of the 455 tested. M. boziis was cul- mal survey was therefore conducted in In mid 1992 neighbouring dairy and tured from the lesion found at slaughter the area in late 1993. small beef breeding herds in the adjacent (Property Z). The infected animal had 20 Surveillance 23(2) 1996 spent some of itslife grazing in the north- not show tuberculosis to a greater degree Acknowledgements ernManawatu districtbut testing of herds before it was discovered at Otaki Beach? on the grazing properties has revealed If the disease had leaked into the local Wewish to thanktheMQMLivestock no problems. wild animals from herds that were infect- Officers, particularly Leo Coonep and A feral animal survey is proposed for ed many years ago why has the disease Tony Clifford, and the Land Manage- this area. taken so long to manifest itself in the ment staff of the Wellington and Mana- farmed livestock? It is therefore most watu / Wanganui Regional Councils who likely that a combination of all four meth- assisted in this study. DNA fingerprinting ods of introduction are involved. Becausebovine tuberculosis was first DNA fingerprinting of M. hmis by References restriction endonuclease analysis (REA) detected in possums in New ZeaIand was developed at Wallaceville(8,'w to there is much evidence to support the (I) Livingstone PG. Tuberculosis in New Zea- assist in epidemiological investigations. belief that possums are indeed the pri- land - current status and control policies. The same REA type was found in M.bovis mary vector for tuberculosis in farmed Surveillance 19jl). 14-8, 1992. Walker R, Reid B, Crewes K. Bovine tuber- isolates from cattle, possums and ferrets cattle and deer.", 4, *. 12, 131 However, the (2) disease hasbeenisolated from most mam- culosis in predators in the Mackenzie Basin. fromManakau, dairy cattle from TeHoro Surveillance 20(2). 11 4, 1993. and a beef animal from Pukehou. This malian species including deer, ferrets, cats, pigs, and goats, and many of these (3j Davidson M. Tuberculosis in possums. Sur- REA type has been seen previously in a veillance 18(5) 16, 1991. species are present in the areas where the possum from Castlepoint (on the east (4) Coleman JD. Distribution, prevalence and coast of the Wairarapa). These results disease breakdowns have le epidemiology of bovine tuberculosis in 17. 2, 6. 16, 17, 16, 19. 20. 21, 22) The significance of suggest that there was a limited intro- brushtail possums, Trichosurus vulpecula, in ductionofM. boziis into thewildlifein this each species as a reservoir and vector of the Hohonu Range, New Zealand. Australian region, and a subsequent spread to do- tuberculosis is not known. Wildlife Research 15(6), 651-63, 1988. Griffin JM, Hahey T, Lynch K,Salman MD, mestic animals. The strains of bouk The significance of isolating the or- (S) M. ganism from the ferret population needs McCarthy J. Hurley T. The association of isolated from Koputaroa and Waitarere cattle husbanw practices, environmental fac- were different from those isolated from further investigation. The fact that two consecutive years of possum control in tors and farmer characteristics with the occur- Te Horo and Manakau but were similar rence of chronic bovine tuberculosis in dairy to other strains from the Wairarapa. The the Otaki Beach area does not seem to be herds in the Republic of Ireland. Preventive results of REA typing of the organism preventing further disease occurring in Veterinary Medicine 17, 145-60, 1993. from the dairy heifer from the Ihakara herds within the control area is of con- (6j Cowan PE. PredatorBovine Tuberculosis herd is pending. cern. In the herds infected initially (Prop- Surveys - Synthesis and Review Landcare erties A and B) no further tuberculosis Research. Contract Report LC9394/107, pre- has been detected. Has the possum con- pared for Animal Health Board, Wellington, Epidemiology of the disease trol or the routine rabbit control caused a 1994. migration of ferrets? We know ferrets (7) Chiefveterinary Officer, Annualreport 1992. Surveillance 20(3), 9-14, 1993. These breakdowns raise three critical move when their major food source be- (8) Collins DM, Gabric DM, de Lisle GW. Typ- questions: comes depleted.'23)The ferret has for a How did the microorganism get into ing of Mycobacterium bovis, isolates from long time been known to be susceptible cattle and other animals in the same locality. the livestock? to bovine tuberculosis infection.(16)Its New Zealand Veterinary Journal 36, 45-6, How is the disease spreading? genetic relationship to the badger could 1988. How can the spread be prevented? aid inour understandingof the disease in (9) de Lisle GW, Hansen M, Yates GF, Collins In many of the recently recognised ferrets and their significance as a poten- DM, Mackenzie KW. Walker R. The epide- endemic areas of New Zealand, the move- tial vector. The dynamics of bovine tu- miology of bovine tuberculosis in the Mac- ment of infected deer seems to havebeen berculosis in badgers has been studied kenzie Basin. Proceeding&of the Deer Branch ofthe New Zealand VeterinaryAssociation7, involved, for example in the Mackenzie widely24,25. 2b' z,and this may help us Basin,(') Waipawa.'1s:8However, in none 34-42, 1990. understand the role that ferrets play in (10) of the Horowhenua and Kapiti break- ColljnsDM,deLisleGW,CollinsJD.Costello the bovine tuberculosis cycle in some E. DNA restriction fragment typing of Myco- downs has there been a severely infected parts of New Zealand. bacteriurnbovis isolates fromcattle andbadg- deer herd from which the disease could Feral deer and pigs are present in the ers in Ireland. The Veterinary Record 134, have spread into the possum or other Tararua foothills behind Manakau and 681-2, 1994. feral animal populations. Pukehou, but not on the beach country. (1I) Mackereth G. The Waipawa Endemic Area: Possible explanations for how the dis- Sambar deer are present around Kopu- the epidemiological picture. Proceedings of ease got into the livestock include: taroa and at times around Waitarere. the Deer Branch of the New Zealand Veteri- Association 10,222-8,1993. movementupthecoastfromPaekaka- These species have been surveyed for nary not (12) Ministry of Agriculture and Fisheries, New riki via a feral source; bovine tuberculosis. Feral red deer are movement over the Tararua ranges Zealand. Possum researchand cattle tubercu- thought to be increasing in numbers along losis. SurveiIlance 13(3}. 18-30, 1986. from thewairarapa withaferalsource; the Tararua foothills between Manakau (I3) Moms RD, Pfeiffer DV, Jackson R, Wilson movement into the areas with stock and Pukehou. PR. Current understanding of the epidemiol- movements; Defining the bovine tuberculosis sta- ogy of tuberculosis. Proceedings of the Deer previous tuberculosis infected herds; tus of these feral species is a key to better Branch ofthe New Zealandveterinary Asso- a combination of all four. understanding of how the bovine tuber- ciation 10,229-45, 1993. The data collected to date do not une- culosis infection is spread in livestock. (14) Beatson NS. Tuberculosis in red deer in New Zealand. Biology of Deer Production, the quivocally support any one of these. The epidemiology of the disease in this Royal Society of New Zealand Bulletin 22, However, because different tuberculosis geographic area is clearly complex and 145-50. 1985. strains are involved it is likely that the could involve interaction between do- (ISj Bertram MF. h'idespredd Tb (Mycobacle- infection has originated from more than mestic animals and several feral species, n'um bovis) infection within a large red deer one source. Linear extension from one the latter either as reservoirs or vectors of herd. Proceedings of a Deer Conference for single reservoir would not explain all of the disease. Veterinarians Rotorua, 78-81, 1986. the findings. For example if the feral an- The significance of the new break- (16) Mannj RP, Adkins JA, Fox JG. Proven or imals in the Tararuas are infected, why down herds at Ihakara and the connec- potential zoonotic diseases of ferrets. Journal are not more herds along the Tararua tion with the Manakau problem further American Veterinary Medical Association 195(7). 990-4, 1989. western boundary showing infection? south and the Koputaroa problem to the (1 7) de Lisle GW. Mycobacterial infection in cats And why are more herds on the western west will be followed up with further and dogs. Surveillance 20(4), 24-6, 1993. side of the Akatarawas not showing evi- feral animal surveys and REA typing. (18) Gumbrell RC. Tuberculosis in cats. Surv-eil- dence of infection? If infection came up The results of this work wiI1 be a key to lance 2I(l), 21, 1994. the coast from Paekakariki why did the the control plan and the placing of a herds at Te Horo and south from there 'buffer' for the 1995196 test year. Continued next page Surveillance 23(2) 1996 21 Recent spread of tuberculosis in the Kapiti and Horowhenua districts Continued from page 2 1

(19) McLaughlin AA. An episode of Mycobacre- rium bovis infection in pigs. Surveillance 16(2), 23-4, 1989. (20) Wakelin CA, Churchman OT. Prevalence of bovine tuberculosis in feral pigs in Central Otago. Surveillance 18(5), 19-20, 1991, (21) Sanson RL. Tuberculosis in goats. Surveil- lance 15(2), 7-8, 1988. (22) Allen GM. Other animals as sources of Tb infection. Proceedings from a Symposium on tuberculosis, Palmerston North, 197-20 I, 1991. (23) Research on mustelids and cats in New Zea- land. Wildlife Research Liaison Group. Re- view (3) 6, 1984. (24) Noonan NL, Sheane, WD, Harper LR, Ryan PJ. Wildlife as a possible reservoir of bovine tuberculosis. Irish Veterinary Journal 29 (I), 1975. (25) Pritchard DC. A century of bovine tuberculosis, 1888-1988. Conquest and Controversy. Journal Comparative Pathology 99, 357-99, 1988. (26) HewsonPI, Simpson WJ. Tuberculosis infection in cattle and badgers in an area of Staf- fordshire. Veterinary Record I20,252-6,1987. (27) Cheeseman CL, Wilesmith JW, Stuart FA, Mallinson PJ. Dynamics of tuberculosis in a naturally infected badger population. Mam- malian Review 18 (I), 61-72, 1988.

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22 Surveillance 23(2) 1996