Table 1. Serologic analysis^a of 22 horse serum samples from five Mexican states, positive for West Nile virus antibodies, July 2002–March 2003^b.

					WNV serologic findings							HI SLEV
State, locality	Sample no.	Date	Age	Sex	IgG-E	IgM	IgG		PRNT	HI
Veracruz, Minatitlan	VER-015	Oct 28, 2002	7 y	M	pos	1,600	400		>320	20	20
Veracruz, Minatitlan	VER-011	Oct 28, 2002	18 m	M	pos	neg	400		>320	160	neg
Veracruz, Hidalgotitlan	VER-017	Oct 29, 2002	8 m	M	pos	12,800	neg		>320	>640	160
Veracruz, Texistepec	VER-26	Oct 29, 2002	2 y	M	pos	neg	100		40	160	neg
Veracruz, Texistepec	VER-025	Nov 7, 2002	18 m	M	pos	6,400	neg		>320	>640	160
Veracruz, J. Carranza	VER-036	Nov 11, 2002	7 m	M	pos	neg	6,400		>320	>640	40
Veracruz, Angel R Cabada	406	Mar 20, 2003	13 m	F	pos	neg		400	>320	80	neg
Veracruz, Cosamaloapan	187	Aug 28, 2002	5 y	F	pos	neg		1,600	>320	160	20
Yucatan, Merida	389	Mar 7, 2003	4 y	F	pos	neg		1,600	nt	80	20
Yucatan, Tizimin	391	Mar 1, 2003	5 y	M	pos	neg		1,600	160	40	20
Chihuahua, Ojinaga	210	Oct 20, 2002	2 y	M	neg	1,600		neg	40	320	40
Coahuila, Cd Acuna	112	Oct 14, 2002	3 y	M	pos	1,600		neg	80	20	20
Coahuila, Hidalgo	4	Sep 1, 2002	5	F	pos	400		100	>320	>640	20
Coahuila, Villa Union	26	Nov 2, 2002	4 y	M	pos	400		100	>320	320	80
Coahuila, Nava	67	Jul 11, 2002	7 y	M	pos	400		100	>320	320	20
Coahuila, P. Negras	56	Nov 5, 2002	2 y	M	pos	6,400		100	>320	>640	40
Coahuila, Zaragoza	39	Oct 10, 2002	5 y	F	pos	neg		400	>160	320	20
Coahuila, Morelos	51	Oct 5, 2002	7 y	M	pos	neg		100	>160	160	40
Tamaulipas, Diaz Ordaz	268	Nov 7, 2002	8 y	F	pos	12,800		1,600	40	320	40
Tamaulipas, Camargo	279	Nov 11, 2002	4 y	F	pos	12,800		3,200	>320	320	80
Tamaulipas, Rio Bravo	349	Nov 5, 2002	8 y	M	pos	neg		400	80	80	neg
Tamaulipas, Victoria	344	Nov 7, 2002	2 y	M	pos	neg		6,400	>320	160	20

^aTiters expressed as reciprocal of dilution; all tests were enzyme-linked immunosorbent assays unless otherwise noted; all tests were against WNV (West Nile virus) unless otherwise noted. ^bSLEV, St. Louis encephalitis virus; Ig, immunoglobin; G-E, recombinant domain III of E protein; PRNT, plaque reduction neutralization test; HI, hemagglutination inhibition test.