6 Disease control

6.1 Tuberculosis (Tb) control

Control of Mycobacterium bovis (Tb) over the agricultural industry is managed by TBfree New Zealand, whose primary objective is to manage Tb to reduce the number of infected herds and to prevent Tb vector free areas becoming vector risk areas. The status of a vector area is determined by the prevalence of wild animals (e.g., possums and ferrets) that are considered a source of infection.

The total number of infected dairy herds in 2022/23 was 7 (Table 6.1). The number of tuberculous dairy cattle increased to 50 from the 42 in 2021/22. This exceeds totals from the past five seasons; however, it is still below the 10-year average of 53.

The West Coast had the greatest number of infected herds (4) in 2022/23, as well as the greatest number of tuberculous dairy cattle (44).

Region	Vector Status	Number of infected dairy herds at the end of the season (30 June)	Number of dairy cattle primary tested during the season	Number of tuberculous dairy cattle
Northland	Free	0	32,905	0
Auckland	Free	0	7,878	0
Waikato	Free	0	287,605	1
	Risk	0	30,077	0
Bay of Plenty	Free	0	45,047	0
	Risk	0	5,756	0
Gisborne	Free	0	1,295	0
Hawkes Bay	Free	0	11,185	2
	Risk	1	22,469	1
Taranaki	Free	0	77,481	0
Manawatu/Wanganui	Free	1	54,180	1
	Risk	0	9,657	0
Wellington	Free	0	1,015	0
	Risk	0	60,011	0
North Island	Free	1	518,591	4
	Risk	1	127,970	1
North Island	Total	2	646,561	5
Marlborough	Free	0	1,586	0
	Risk	0	838	0
Tasman/Nelson	Free	0	10,316	0
	Risk	0	9,667	0
West Coast	Free	0	5,148	0
	Risk	4	176,240	44
Canterbury	Free	0	177,135	0
	Risk	0	63,206	0
Otago	Free	0	81,185	0
	Risk	1	117,435	1
Southland	Free	0	109,089	0
	Risk	0	43,262	0
South Island	Free	0	384,459	0
	Risk	5	410,648	45
South Island	Total	5	795,107	45
New Zealand	Free	1	903,050	4
	Risk	6	538,618	46
New Zealand	Total	7	1,441,668	50

Note:
- Sourced from TBfree New Zealand.
- Tuberculous animals include lesioned reactor cattle and lesioned cull cattle.

The trend in the number of infected herds, by island and for the country as a whole, is presented in Graph 6.1. Nationally, the past 17 seasons has seen an 86.8% decrease in the number of infected herds. The overall number of infected animals has also decreased (85.8%) over the same period (Graph 6.2).