TABLE 2.

Classification of place and time period of transmission of TB cases in the Rotterdam region, 1995 to 2006

Criteriona	Place of infection					Time of infection for patients infected in The Netherlandse
	Infected in a foreign country		Indeterminateb	Infected in The Netherlands		≤2 yrs	>2 yrs	Unknown
	Confirmed	Probably		Probably	Confirmed
Cases with a unique fingerprint (n = 919)
Cases in immigrants (n = 700)
Arrived in The Netherlands after 1/1/1993	376
In residence before 1/1/1993 and had documented contact with PTB case in The Netherlands				18	1	1c	18
In residence before 1/1/1993 and had documented history of frequent travel to countries where TB is endemic		79
In residence before 1/1/1993 and lived more yrs in foreign country than in The Netherlands in the pregenotyping period		170
In residence before 1/1/1993 without identified risks			56
Cases in nonimmigrants (n = 219)
Documented contact with PTB case in The Netherlands					39	1c	38
Documented history of frequent travel to countries where TB is endemic		32
No documented risks				148			148
Cases with a clustering fingerprint (n = 1,108)
No preceding PTB in the clusterd (n = 62)	29	21		12		2c	10
Diagnosis within 3 mo of arrival	32
Not in residence in The Netherlands with a clustered TB case	32
Cases with a confirmed epidemiological link					258	195	63
Cases with a possible epidemiological link					190	185	5
Cases without an established epidemiological link				534		401	133
Cases without a DNA fingerprint (n = 609)
Documented contact with PTB case in The Netherlands					192	154	38
Documented contact with PTB case in a foreign country	13
Chest X-ray abnormalities or positive TST at entrance screening	43
Cases in immigrants who lived more yrs in a foreign country than in The Netherlands		151
Cases in immigrants without other documented risks			70
Cases in nonimmigrants with documented history of frequent travel to countries where TB is endemic		14
Cases of recurrent TB in nonimmigrants				13			13
Cases in nonimmigrants without documented risks				113				113
Total (n = 2,636)	525	467	126	838	680	939	466	113
%	19.9	17.7	4.8	31.8	25.8	35.6	17.7	4.3

^aDates are given as month/day/year. PTB, pulmonary tuberculosis; TST, tuberculin skin test.

^bTwenty-two of 56 and 21 of 70 cases had unknown dates of arrival in The Netherlands.

^cPatients were infected by a visiting person later diagnosed with infectious TB shortly after leaving The Netherlands.

^dThese clustered cases without a preceding PTB were classified according to the trees for unique fingerprints.

^eThe classification of time of infection for 994 clustered cases infected in The Netherlands, presented in boldface in this table, is explained in Fig. 1.