TABLE 1.

FIV diffusion in the shelter where the vaccination experiment was conducted

Parameter	Yr
	1991	1992	1993	1994	1995	1996a	1997	1998
No. of cats in shelter	76	123	164	146	108	91	82	78
No. FIV seropositive/no. examined	22/76	35/83	45/85	36/62	29/75	24/74	27/65	32/61
Preexisting		21	34	33	23	16	19	26
New arrivals		9	4	0	1	2	1	0
Seroconversions		5	7	3	5	6	7	6
FIV prevalence (%)	29	43	53	58	39	32	41	52
FIV incidence (%)		9	15	10	10	11	15	17
No. of FeLV p17 positive cats/no. examined	1/76	7/83	7/85	2/62	9/75	9/74	7/65	1/60

^aImmunizations started in January 1996.