Table 2. Comparison between each two groups as regards the levels of antistreptolysin O titer.

	Acute RF(1st attack)	Recurrent RF	Chronic RHD	Acute f. tonsillitis	H of recurrent f. tonsillitis
1) Controls	<0.0001	<0.0001	0.08	<0.0001	<0.0001
2) Acute RF (1st attack)		<0.0001	<0.0001	>0.99	>0.99
3) Recurrent RF			<0.0001	<0.0001	<0.0001
4) Chronic RHD				<0.0001	<0.0001
5) Acute follicular tonsillitis				<0.0001	>0.99

ARF, acute rheumatic fever; RHD, rheumatic heart disease; H of recurrent F tonsillitis, history of recurrent follicular tonsillitis.