|
Dr. Lisa Conti, State
Public Health Veterinarian
Jerne Shapiro, MPH,
Florida EIS
David
Atrubin, MPH, Florida EIS for Hillsborough County
Fermin Arguello, MD,
MPH, Florida (CDC) Epidemic Intelligence Service
Melanie Black, MSW, Professional Training Cooridinator, Bureau of
Epidemiology
Caroline Collins, Arbovirus Surveillance
Coordinator
Lisa Conti, DVM, MPH, State Public Health
Veterinarian
D’Juan Harris, GIS Coordinator
|
|
►Investigation
of Blood Transfusion-Associated West Nile Virus
Infection
September through
October 2002, a 7 year old boy received 37 blood products for his
underlying anemia. A day
after his discharge from the hospital on October 7, he was readmitted with fever, malaise and rash; he
subsequently developed encephalopathy. A lumbar puncture revealed elevated
protein and WNV IgM antibody; the patient recovered and was discharged.
Retention segments were available for 36 of 37 donors; one retention
segment was equivocal (one sample positive and one negative) for WNV by
kinetic quantitative PCR assay (TaqMan®), and the remaining 35 were
negative. A recent blood
sample obtained from the donor revealed IgM antibodies to West Nile virus,
although the donor did not report clinical signs of West Nile virus
infection near the time of his blood donation. As a result of this investigation,
a second recipient of this donor's blood products was found to have
antibodies to West Nile virus. Histories of both individuals diminish the
likelihood that they became infected from mosquito bites; findings
indicate that the patients became infected through transfusion of blood
products.
Federal, state and local collaborators continue to
investigate West Nile virus (WNV) infections in recipients of blood
transfusions. During 2002, over 3,900 West Nile cases were reported in the
United States. Fifty-eight
reports of possible transfusion associated transmission were investigated;
to date 17 cases have been confirmed. Currently there are no FDA
approved tests for donor screening.
Prior to 2002 transmission of West Nile virus through transfusion
had not been documented.
Back
to top
►Chickenpox
Outbreak in a Hillsborough County Elementary
School
Introduction
On October 14, 2002, the
Hillsborough County Health Department received a report of a chickenpox
outbreak at an area elementary school. Preliminary reports indicated 26
students had exhibited symptoms of chickenpox (fever, malaise and a
blistering rash). Schools
nurses reported that both vaccinated and unvaccinated students were among
the ill.
Methods
The school nurse provided the following
data for each of the affected students: date of disease onset, grade
level, teacher, chickenpox vaccination status and length of time of school
absence. Additionally, total
enrollment figures, number of students per grade level, number of staff
members and information about pregnant staff and immune compromised
individuals were made available.
Cases were identified both
clinically and epidemiologically.
At least 3 of the affected students were seen by physicians who
diagnosed the disease as chickenpox.
Most of the other cases were identified by the students’ parents
who subsequently reported the illnesses to the school. The school nurse diagnosed several
of the cases as well. All
cases were identified between September 23, 2002 and October 25,
2002.
Attack rates were calculated for each grade and for the
entire student body. The
dates of onset were entered into a Microsoft Excel spreadsheet and an
epidemiological curve showing number of cases by disease onset date was
produced. Additionally, a
table was constructed showing the cases by grade level and vaccination
status. Procedures for
tracking further cases were instituted.
An analysis was conducted
to explore differences in severity of disease between the vaccinated and
unvaccinated students. Data
were not available as to the severity of the illness (including the number
of lesions) for the affected students, however, the number of days absent
from school was provided by the school’s staff. A two-sample t-test was executed
to determine if the previously vaccinated students suffered a milder
(shorter) illness than those without a history of vaccination. A p-value was calculated using a
two-tailed t-test and assuming equal variances among vaccinated and
unvaccinated cases.
Disease control methods were recommended to
school officials. School
nurses were instructed to exclude all affected students from school until
all lesions had crusted over.
School officials were asked to identify any immune compromised
students who would be at particular risk of complications from chickenpox
infection. Pregnant staff
members were told to consult their OB/GYN doctors. A letter, which related basic
information about chickenpox and the chickenpox vaccine, was sent home to
each of the families of the children attending the school.
The Florida Bureau of
Immunization, the Center for Disease Control and Prevention and
Hillsborough County infectious disease doctors were consulted with respect
to vaccination recommendations for the students.
Results
Twenty-seven
students were infected with the varicella virus that causes chickenpox
between the dates of 9/23/02 and 10/25/02. Table 1 below shows that the
overall attack rate among students was 2.85%. The second and third grade classes
were most affected by the outbreak with attack rates of 5.95% and 6.00%,
respectively. The fourth and
fifth grades were largely unaffected with only one case among the students
in those two grades. It is
noteworthy that the kindergarten and first grade class had attack rates of
3.47% and 1.41%, respectively.
For the last two years, all incoming elementary school students
have been required to have had the chickenpox vaccine or a history of
chickenpox prior to beginning school. Therefore, if the vaccine were
completely effective and the histories of chickenpox accurate, the degree
of immunity to varicella, in those two grades, should have been
effectively 100% (some students are exempted from vaccination because of
medical conditions or religious beliefs).
| Table
1. Chickenpox Attacks
Rates - Total and by Grade Level (N=27)
|
Grade Level
|
Number of Cases |
# of Students |
Attack Rate |
| KG |
5 |
144 |
3.47% |
| 1 |
2 |
142 |
1.41% |
| 2 |
10 |
168 |
5.95% |
| 3 |
9 |
150 |
6.00% |
| 4 |
0 |
150 |
0.00% |
| 5 |
1 |
192 |
0.52% |
| Total |
27 |
946 |
2.85%
|
Table
2 demonstrates that 11 of the 27 cases of chickenpox occurred in students
with a history of vaccination.
As expected, all 7 of the cases among kindergarteners and first
graders had received the chickenpox vaccine.
Of the 10 second graders, 4 of them had been
vaccinated.
|
Table 2. Chickenpox cases at an
elementary school by grade and vaccination
status ( N=27) |
|
|
|
|
Grade
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
KG
|
1
|
2
|
3
|
4
|
5
|
Total for all
grades |
Vaccination Status |
Yes
|
5
|
2
|
4
|
0
|
0
|
0
|
11 (40.7%)
|
|
|
No
|
0
|
0
|
6
|
9
|
0
|
1
|
16 (59.3%)
|
|
|
Total
|
5 (18.5%)
|
2 (7.4%)
|
10 (37.0%)
|
9 (33.3%)
|
0 (0%)
|
1 (3.7%)
|
27
|
Figure 1 shows the number of cases by date.
This epidemiological curve, with its bimodal pattern, is indicative
of a person-to-person outbreak.
The time difference between peaks of 14-16 days coincides closely
with the known incubation period of the varicella virus and also indicates
that those cases with onsets around 9/25 likely infected those with onsets
around 10/9.
It is also evident from the epidemiological curve that the index
case was never identified, since no case was found during the time period
14-16 days before the first group of cases.
Unvaccinated cases were ill for an average of 7.9 days
(standard deviation = 3.4 days), whereas the vaccinated cases’ illnesses
lasted an average of 7.7 days (standard deviation = 4.7 days). The p-value for the two-sample
t-test was 0.89 confirming that there was no statistically significant
difference in length of school absence between the two
groups.
After consulting with the state, the CDC and the infectious
diseases doctors, the decision was made to inform the families of the
students at the school about vaccination but not to specifically recommend
immunizations. Procedures
were instituted for tracking additional cases that could occur. No cases were reported after
October 25, 2002.
Discussion
Clearly, the most intriguing
finding from this study is that 11 out of the 27 (40.7%) of the cases of
chickenpox occurred in children with a history of vaccination. Unfortunately, a vaccine efficacy
rate could not be calculated, because the vaccine status of every student
was not obtained. It is
evident that significant vaccine failure did occur. A recent New England Journal of
Medicine article investigating an outbreak of chickenpox at a day-care
center yielded vaccine efficacy rates of 44.0% against disease of any
severity and 86.0% against moderate or severe disease (Galil et al.,
2002).
In the
investigation presented here, the vaccinated and unvaccinated students
were absent from school for nearly the same length of time. However, the school nurse did
report that the vaccinated children were, for the most part, suffering
milder illnesses with fewer lesions than the unvaccinated students.
Of the 11 cases that
occurred among the elementary school students with a history of
vaccination, only one student was vaccinated within the last 3 years. In their study, Galil et al.
(2002) found that those day-care attendees vaccinated longer than 3 years
ago had 2.6 times the risk of getting chickenpox compared to those who
were vaccinated within the last 3 years. The issue of waning immunity after
vaccination merits further study.
The index case at the elementary
school was never identified, but if this child were among the vaccinated,
he or she may have experienced few lesions and minimal illness. Unfortunately, this breakthrough
illness can be just as infectious as a more severe case of
chickenpox. From the
epidemiological curve, it appears that the index case may have infected 11
other students.
Several limitations were
present in the study. Case
diagnosis was primarily based on the parent reporting that the child had
chickenpox. In addition, no
good data indicating the severity of the illness were available for the
affected students. Finally,
since the index case was never identified, it is difficult to trace the
transmission of the disease through the school. The first group of cases included
students from first, second, third and fifth grades.
Chickenpox
vaccination appears to have limitations in preventing disease, however it
does seem to provide good protection in moderating the illness. Since, prior to the vaccination
era, varicella caused approximately 11,000 hospitalizations (Galil (b) et
al., 2002) and 100 deaths (Meyer et el., 2000) annually, a good case can
be made for vaccination. The
question of waning immunity needs to be studied in greater detail to
determine the long-term implications of chickenpox vaccination.
In
the event of an outbreak in a school, it is critical that symptomatic
students are excluded from school until their lesions have crusted
over. Vaccination of
household and school contacts can be utilized as an effective means of
preventing severe cases of chickenpox and limiting the spread of the
disease.
References
Galil K, Lee B, Strine T, Carraher C,
Baughman A, Eaton M, Montero J, Seward J. Outbreak of varicella at a
day-care center despite vaccination.
N Engl J Med 2002;347:1909-15.
Galil K (b), Brown C, Lin F,
Seward J. Hospitalizations
for varicella in the United States, 1998 to 1995. Pediatr Infect Dis J
2002;21:931-5.
Meyer
PA, Seward JF, Jumaan AO, Wharton M.
Varicella mortality: trends before vaccine licensure in the United
States, 1970-1994. J Infect
Dis 2000;182:383-90
Back
to top
► Requesting Assistance From Local Health
Departments Regarding Possible Transmission of Legionnaires’ Disease -
Islamorada (Florida Keys), FL
On January 23, 2003,
the Florida Department of Health (DOH) became aware of two cases of
Legionnaires’ disease from residents of Michigan and Pennsylvania after
their return from a vacation in the Florida Keys. Their dates of onset
were December 25, 2002 and January 5, 2003. It appears that the only
epidemiological link between these two cases was their vacation to the
Florida Keys between December 12, 2002 and January 3, 2003.
An
investigation has ensued to further determine whether the exposure
occurred in the Florida Keys.
As part of the investigation the DOH is trying to determine if
there are additional cases and requests that local health departments
heighten their activities in identifying cases suspicious for
Legionnaires' Disease.
Additionally, the DOH requests that any Legionnaires’ cases with
travel to the Florida Keys within ten days of symptom onset be reported to
the Bureau of Epidemiology (850-245-4406).
Back
to top
►AHRQ Web-Assisted Audio Conferences on
Bioterrorism and Health
System Preparedness. (Agency for Healthcare Research
and Quality, Dept of Health and Human
Services)
Mark your calendars! AHRQ is sponsoring a new series of
five free Web-assisted audio conference calls on bioterrorism and health
system preparedness. These
90-minute calls are designed to share the latest health services research
findings, promising practices, and other important information with State and
local health officials and key health systems decision makers. The first call of this series will
beheld on Tuesday, February 28, from 2:00 to 3:30 p.m., EST, and will
focus on smallpox immunization issues, strategies, and tools. Visit www.hsrnet.net/ahrq-ulp/bioterrorism to see the agenda
and to register.
Back
to top
►Arboviral Activity Summary through the
Week Ending January 27, 2003
Disclaimer: Please note that numbers are
subject to change with confirmatory information.
During
the period of January 21, 2003 through January 27, 2003, the following
arbovirus activity (St. Louis encephalitis [SLE] virus, eastern equine
encephalomyelitis [EEE] virus, West Nile [WN] virus and dengue virus) was
recorded for Florida:
Human: No
new cases of arboviral
meningo-encephalitis were reported this week.
Sentinel
Chickens: Twelve WN seroconversions were confirmed in Duval
(1), Hendry (1), Hillsborough (2), Indian River (1), Manatee (1), Orange (1), Osceola (1), Palm
Beach (2) and Seminole (2)
counties. All
reports represent 2002 activity. This week, 494
samples were tested from 12 counties.
Equine*: No new cases of equine arboviral
infection were reported this week.
Bird
Mortality: Upon further testing, one dead
bird from Bay County (collected 11/19/02) was reported positive for
EEE.
In
2002, 3,370 birds were tested and an additional 400+ were too decomposed
to be tested. Last year,
9,993 bird reports were logged representing 11,680 dead birds; 1,230 (11%)
were crows; 1,353 (12%) were blue jays and 320 (3%) were raptors. Thus far in 2003,
247 reports have been logged representing 324 dead birds; of these, 91
were tested and results were negative.
To
report dead birds use http://wildflorida.org/bird/.
Online
bird identification sites include: http://www.mbr-pwrc.usgs.gov/id/framlst/framlst.html
or http://data.acnatsci.org/ornithology/vireo.php.
Mosquito
Pools: No
new mosquito pools were reported WN or EEE positive this week. Over 4,200 mosquito pools
collected during 2002 were submitted for testing at the DOH Tampa
Laboratory. At least 982
additional pools were tested by mosquito control agencies and 298 pools
were tested by Department of Defense installations in the
state.
The
Disease Outbreak Information Hotline offers updates on medical alert
status and surveillance at
888-880-5782.
Florida is
currently at “Level 1” in the Arbovirus Response Plan (see http://www9.myflorida.com/disease_ctrl/epi/htopics/arbo/index.htm). DOH Press releases can be seen at
http://apps3.doh.state.fl.us/IRM/PressReleaseSearch/search.cfm
.
2003
Cumulative Arbovirus Activity by County
1.
Human Surveillance
No
new activity for 2003 has been reported for WN, SLE, EEE or
Dengue.
2. Animal Surveillance
West
Nile Virus
Positive
samples from 2 sentinel chickens in 1
county were received. Date of first positive bleed is shown in
parentheses.
Bay: 2
sentinel chickens (1/7, 1/7)
Back to top
► Weekly Disease
Table : Week
3
Florida Department of
Health, Bureau of Epidemiology
Weekly Morbidity Report, Week 3, ending
January 18, 2003
Selected Diseases and Conditions (Confirmed Cases
Only)
|
Disease |
2003
Week 3
|
2002
Total
|
2001
To Week 3
|
2002
To Week 3
|
2003
To Week
3 |
Average For 2001 Through 2003 To Week 3
|
2003
Percent Change From Average
|
|
ANIMAL BITE, PEP
RECOMMENDED |
16 |
1082 |
13 |
42 |
49 |
34.67 |
41 |
|
ANIMAL
RABIES |
0 |
37 |
4 |
0 |
0 |
1.33 |
-100 |
|
ANTHRAX |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
BOTULISM |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
BRUCELLOSIS |
0 |
6 |
0 |
0 |
0 |
0.00 |
0 |
|
CAMPYLOBACTERIOSIS |
20 |
980 |
11 |
85 |
50 |
48.67 |
3 |
|
CIGUATERA |
0 |
7 |
0 |
0 |
0 |
0.00 |
0 |
|
CRYPTOSPORIDIOSIS |
1 |
101 |
0 |
3 |
2 |
1.67 |
20 |
|
CYCLOSPORIASIS |
0 |
32 |
0 |
0 |
0 |
0.00 |
0 |
|
DENGUE
FEVER |
0 |
12 |
0 |
1 |
0 |
0.33 |
-100 |
|
DIPHTHERIA |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
EHRLICHIOSIS,
HUMAN |
0 |
2 |
0 |
0 |
0 |
0.00 |
0 |
|
EHRLICHIOSIS, HUMAN
GRANULOCYTIC |
0 |
1 |
0 |
0 |
0 |
0.00 |
0 |
|
ENCEPHALITIS, EASTERN
EQUINE |
0
|
1
|
0
|
0
|
0
|
0.00
|
0
|
|
ENCEPHALITIS,
POST-INFECTIOUS |
1
|
17
|
0
|
2
|
1
|
1.00
|
0
|
|
ENCEPHALITIS,
ST. LOUIS |
0
|
1
|
0
|
0
|
0
|
0.00
|
0
|
|
ENCEPHALITIS,
VENEZUELAN |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
ENCEPHALITIS, WEST NILE
VIRUS |
0 |
27 |
0 |
0 |
0 |
0.00 |
0 |
|
ENCEPHALITIS, WESTERN
EQUINE |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
ESCHERICHIA COLI,
O157:H7 |
0 |
62 |
0 |
2 |
3 |
1.67 |
80 |
|
ESCHERICHIA COLI,
OTHER |
0 |
22 |
0 |
1 |
1 |
0.67 |
50 |
|
GIARDIASIS |
20 |
1279 |
3 |
102 |
48 |
51.00 |
-6 |
|
H. INFLUENZAE INVASIVE
DISEASE |
5 |
94 |
3 |
6 |
10 |
6.33 |
58 |
|
HANTAVIRUS
INFECTION |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
HEMOLYTIC UREMIC
SYNDROME |
0 |
4 |
0 |
0 |
0 |
0.00 |
0 |
|
HEMORRHAGIC
FEVER |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
HEPATITIS
A |
15 |
1010 |
4 |
48 |
34 |
28.67 |
19 |
|
HEPATITIS B {+HBsAg IN PREGNANT
WOMEN} |
8 |
632 |
0 |
30 |
20 |
16.67 |
20 |
|
HEPATITIS B PERINATAL,
ACUTE |
0 |
7 |
0 |
0 |
0 |
0.00 |
0 |
|
HEPATITIS B,
ACUTE |
9 |
538 |
2 |
31 |
22 |
18.33 |
20 |
|
HEPATITIS B,
CHRONIC |
8 |
541 |
0 |
20 |
28 |
16.00 |
75 |
|
HEPATITIS C,
ACUTE |
3 |
60 |
0 |
1 |
6 |
2.33 |
157 |
|
HEPATITIS C,
CHRONIC |
158 |
3636 |
0 |
51 |
355 |
135.33 |
162 |
|
HEPATITIS NANB,
ACUTE |
0 |
8 |
0 |
0 |
0 |
0.00 |
0 |
|
HEPATITIS UNSPECIFIED,
ACUTE |
0 |
1 |
0 |
0 |
1 |
0.33 |
200 |
|
HUMAN
RABIES |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
LEAD
POISONING |
24 |
1031 |
1 |
51 |
48 |
33.33 |
44 |
|
LEGIONELLOSIS |
1 |
85 |
0 |
6 |
8 |
4.67 |
71 |
|
LEPROSY {HANSENS
DISEASE} |
1 |
4 |
0 |
0 |
1 |
0.33 |
200 |
|
LEPTOSPIROSIS |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
LISTERIOSIS |
0 |
28 |
0 |
2 |
2 |
1.33 |
50 |
|
LYME
DISEASE |
1 |
78 |
0 |
2 |
5 |
2.33 |
114 |
|
MALARIA |
1 |
75 |
0 |
3 |
5 |
2.67 |
87 |
|
MEASLES |
0 |
2 |
0 |
1 |
0 |
0.33 |
-100 |
|
MENINGITIS, OTHER
BACTERIAL |
2 |
210 |
1 |
24 |
17 |
14.00 |
21 |
|
MENINGOCCOCAL
DISEASE |
1 |
109 |
3 |
8 |
9 |
6.67 |
35 |
|
MERCURY
POISONING |
0 |
8 |
0 |
0 |
0 |
0.00 |
0 |
|
MONKEY
BITE |
0 |
1 |
0 |
0 |
0 |
0.00 |
0 |
|
MUMPS |
0 |
6 |
0 |
0 |
0 |
0.00 |
0 |
|
NEUROTOXIC SHELLFISH
POISONING |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
OTHER VIBRIO
INFECTIONS |
0
|
43
|
0
|
1
|
0
|
0.33
|
-100
|
|
PERTUSSIS |
0
|
39
|
0
|
0
|
1
|
0.33
|
200
|
|
PLAGUE |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
POLIOMYELITIS |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
PSITTACOSIS |
0 |
2 |
0 |
0 |
0 |
0.00 |
0 |
|
Q
FEVER |
0 |
1 |
0 |
0 |
0 |
0.00 |
0 |
|
ROCKY MOUNTAIN SPOTTED
FEVER |
0
|
9
|
0
|
0
|
0
|
0.00
|
0
|
|
RUBELLA |
0
|
5
|
0
|
0
|
0
|
0.00
|
0
|
|
RUBELLA,
CONGENITAL |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
SALMONELLOSIS |
60 |
4475 |
23 |
203 |
161 |
129.00 |
25 |
|
SHIGELLOSIS |
65 |
2220 |
9 |
54 |
178 |
80.33 |
122 |
|
SMALLPOX |
0
|
0
|
0
|
0
|
0
|
0.00
|
0
|
|
STAPHYLOCOCCUS
AUREUS {GISA/VISA} |
0
|
0
|
0
|
0
|
0
|
0.00
|
0
|
|
STAPHYLOCOCCUS
AUREUS {GRSA/VRSA} |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
STREPTOCOCCAL DISEASE INVASIVE
GROUP A |
8 |
218 |
2 |
21 |
15 |
12.67 |
18 |
|
STREPTOCOCCUS PNEUMONIAE,
INVASIVE DISEASE |
18 |
648 |
21 |
52 |
48 |
40.33 |
19 |
|
TETANUS |
0 |
3 |
0 |
0 |
0 |
0.00 |
0 |
|
TOXOPLASMOSIS |
0 |
28 |
0 |
3 |
0 |
1.00 |
-100 |
|
TRICHINOSIS |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
TULAREMIA |
0 |
0 |
0 |
0 |
0 |
0.00 |
0 |
|
TYPHOID
FEVER |
0
|
19
|
0
|
4
|
0
|
1.33
|
-100
|
|
VIBRIO
CHOLERAE TYPE O1 |
0
|
0
|
0
|
0
|
0
|
0.00
|
0
|
|
VIBRIO
PARAHAEMOLYTICUS |
1
|
23
|
0
|
0
|
2
|
0.67
|
200
|
|
VIBRIO
VULNIFICUS |
0
|
20
|
0
|
0
|
0
|
0.00
|
0
|
|
WEST
NILE FEVER |
0
|
8
|
0
|
0
|
0
|
0.00
|
0
|
|
YELLOW
FEVER |
0
|
0
|
0
|
0
|
0
|
0.00
|
0
|
|
