Texas Preventable Disease News, Volume 51, Number 2, January 26, 1991 Page: Page2

                                
1 91 -209

TPDN 1991, Vol. 51, No. 2

MAR   5 1991

Page 2

EPI NOTES
Mumps Outbreak in Floyd County: In October and November 1990, an outbreak of mumps occurred
among a population of 319 high school students in which more than 98% of students had been
immunized, according to school records. Sixty-two cases of mumps (seven serologically confirmed)
were identified among students (attack rate=22%) between October 3 and November 23, 1990. There
were five generations of transmission during the outbreak. Only two patients were immunized before
onset of illness. These data suggest that sustained transmission of mumps can occur in a highly
immunized population.
INFLUENZA - TEXAS, 1990-91 SEASON

Influenza virus activity has become more wide-
spread in Texas as we approach mid-January.
Currently, five cities have reported positive viral
isolates. Influenza A and B isolates have been
reported from Houston, San Antonio, and Austin.
Temple has reported one influenza A isolate, and
Waco, an influenza B isolate.
Influenza B (Yamagata) is the predominant virus
in circulation, with influenza A virus appearing
sporadically. One of the influenza A isolates
(from Houston) has been subtyped as HlN1.
Houston experienced significant influenza B
activity in November 1990, with reported cases
of flu and flu-like illness exceeding 1,000 per
week as early as Week 44 (Table 1). In contrast,
the first week in which case totals exceeded 1,000
per week in Houston during the 1989-1990 flu
season was Week 49 (mid-December); the pre-
dominant virus in circulation during this previ-
ous season was influenza A, which tends to show
increased activity in Texas beginning in Decem-
ber.

1990
1989

Table 1.
Reported flu and flu-like illness, Texas
Oct.-Dec. 1989,1990

November
(weeks 44-47)
9,377
5,676

October
(weeks 40-43)
4,685
4,128

December
(weeks 48-52)
42,447
47,766

To date, the Influenza Research Center at Baylor
College of Medicine in Houston has reported 85
influenza B isolates. With the exception of one B
virus isolated from a 40-year-old, all influenza B
isolates have come from throat swabs collected
from pediatric patients, predominantly elemen-
tary and middle-school children (Figure 1).
Figure 1.
Distribution of influenza B isolates from children by age group
Houston, November-December 1990

# 45-

0
f
s
0
a
t
e
s

40-
35 -
30
25-
20-
16-
10-
5-
0-

19%
4% 16
3

46%

26%
22
6%
- 6

38

<1            1-4            5-9           10-14           15-19

Ages (years)
Influenza B virus morbidity generally affects
children more than adults. Influenza B viruses
Total   change antigenically at a slower rate than influ-
enza A viruses. Many adults have partial immu-
56,509   nity because of prior exposure to influenza B
57,570   viruses antigenically similar to current strains.

AIDS MONTHLY STATISTICAL SUMMARY

AIDS Cases and Deaths by Year of Diagnosis,
Texas -- January 19, 1991

3000 -
2500
2000

1500
1000
500
0

1980-1985  1986

1987     1988    1989    1990
Year of Diagnosis

Distribution of Counties by Number of
Reported AIDS Cases,
Texas -- January 19, 1991
140
#
120j
100

C
0
u
n
e
s

80
60
40-
20
0

=Deceased         - Living

-    --      - -      -     -
0     1-9  10-50  51-100  100-1000  1,000
Number of Cases

Cumulative: Cases 11,624 Deaths 7,302

0
f
C
a
S
e
S

. .

N -254

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