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This section presents information on the public health importance of selected nationally notifiable diseases reported from the states to CDC, including a) domestic and some international disease outbreaks, b) active surveillance findings, c) changes in data reporting practices, d) the impact of prevention programs, e) the emergence of antimicrobial resistance, and f) changes in immunization policies. This information is intended to provide a context in which to interpret surveillance and disease-trend data and to provide further information on the epidemiology and prevention of selected diseases.
AIDS
Since the use of highly active antiretroviral therapy (HAART) in the United
States became widespread in 1996, the number of persons diagnosed with
acquired immunodeficiency syndrome (AIDS) has declined. The number of deaths
among persons with AIDS has also declined substantially; as a result, the
number of persons living with AIDS has increased (1).
By December 2001, a total of 807,075 adults and 9,074 children had been
reported with AIDS.
In 1996, sharp declines in AIDS incidence occurred for the first time; during 1998-1999, declines in AIDS incidence began to level, and essentially no change occurred from 1999 through 2000. Through December 2001, 462,653 adult and 5,257 pediatric AIDS cases resulted in death. Since 1996, the number of deaths among persons with AIDS declined sharply and continued to decline each year through 2000. The number of persons living with AIDS, approximately 362,827, was the highest ever reported; of these persons, 78% were men and 61% were black or Hispanic. Of the 282,250 adult and adolescent men with AIDS, 57% were men who have sex with men, 24% were injecting drug users, 9% were exposed through heterosexual contact, and 8% were both men who have sex with men and injecting drug users. Of the 76,696 adult and adolescent women with AIDS, 59% were exposed through heterosexual contact and 38% through injecting drug use (2).
To provide better data for prevention of human immunodeficiency virus (HIV) infection (the virus that causes AIDS), CDC and CSTE recommend that national surveillance include the monitoring of both HIV infection and AIDS (3,4). CDC supports several supplemental surveillance projects that collect data on barriers to preventing AIDS cases and deaths of persons with AIDS, including access to HIV testing and treatment in accordance with current public health service guidelines.
Anthrax
In September and October 2001, in an unprecedented biological terrorism event,
letters containing Bacillus anthracis spores were sent through
the U.S. Postal Service to various addresses in several states. Eleven
inhalational and 11 cutaneous (four suspected and seven confirmed) anthrax
cases resulted. Five of the 11 inhalational infections were fatal. These
bioterrorism-associated cases occurred among residents of seven states
along the East Coast of the United States: Connecticut, one case; Florida,
two cases; Maryland, three cases; New Jersey, five cases; New York City,
eight cases (includes a case in a New Jersey resident exposed in New York
City); Pennsylvania, one case; and Virginia, two cases. In addition to
the 22 bioterrorism-associated cases, one naturally occurring case of cutaneous
anthrax (associated with direct exposure to livestock that had died of
anthrax) was reported from Texas in the summer of 2001. B. anthracis remains
a Category A bioterrorism threat agent.
Botulism
Thirty-nine cases of foodborne botulism were reported in 2001 through NNDSS.
An outbreak of foodborne botulism in Texas involving nine culture-confirmed
and seven clinically diagnosed cases was caused by commercially produced
chili sauce and likely occurred because of time and temperature abuse of
the food at a retail salvage store. The highest annual frequency of infant
botulism, 97 cases, was reported in 2001. The number of wound botulism
cases reported in 2001 was 19. Botulism surveillance conducted by the Foodborne
and Diarrheal Diseases Branch, NCID, indicated 33 foodborne cases, 112
cases of infant botulism, and 23 cases of wound botulism. Clostridium
botulinum toxin is a Category A bioterrorism threat agent.
Brucellosis
In 2001, the control program for brucellosis among cattle in the United States
has nearly eliminated Brucella abortus infection from U.S. herds.
Therefore, at present, the risk of contracting brucellosis either from
occupational exposure to livestock in the United States or from domestically
produced food products is minimal. However, a risk remains for infection
with both B. abortus and B. melitensis from consumption
of unpasteurized goat and cow milk products, in particular those produced
outside the United States. Most cases in the United States are now seen
in international travelers or recent immigrants. Hunters exposed to infected
wildlife and laboratory personnel working with Brucella species
also have an elevated risk for infection. B. melitensis and B.
suis are considered Category B bioterrorism threat agents.
Chancroid
During 2001, a total of 38 cases of chancroid were reported (rate: 0.01 cases/100,000
population), representing a 51% decline from 2000 and a continuing decline
since 1987 (1). However, chancroid is difficult to culture and
could be substantially underdiagnosed. Several studies that used DNA amplification
tests (which are not commercially available) have identified this infection
in cities where it was previously undetected (2).
Chlamydia trachomatis, Genital Infection
During 2001, a total of 783,242 cases of genital chlamydial infection were
reported (rate: 278.32/100,000). This rate was the highest since voluntary
case reporting began in the mid-1980s and the highest since genital chlamydial
infection became a nationally notifiable disease in 1995 (1).
This increase could be caused in part by the continued expansion of chlamydia
screening programs and increased use of more sensitive diagnostic tests
for this condition.
Cholera
During 1995-2000, 61 laboratory-confirmed cases of cholera, all caused by Vibrio
cholerae O1, were reported to CDC. Thirty-five (57%) patients were hospitalized,
and one died. Thirty-seven (61%) infections were acquired outside the United
States, whereas six (10%) were acquired through consumption of contaminated
seafood harvested in Gulf Coast waters (1). Only three laboratory-confirmed
cases of cholera were reported to CDC in 2001. All were caused by V. cholerae O1
and were acquired outside
the United States. All three isolates were resistant to trimethoprim-sulfamethoxazole,
sulfisoxazole, streptomycin, and furazolidone. Thus, foreign travel continues
to account for most cholera cases in the United States, and antimicrobial resistance
is common among V. cholerae O1 strains isolated from ill travelers.
Production and sale of the only licensed cholera vaccine in the United States
ceased in 2001.
Coccidioidomycosis
In recent years, Arizona has experienced a significant increase in the incidence
rates of coccidioidomycosis, from 18/100,000 in 1997 to 42/100,000 in 2001.
This increase is likely related to demographic and climactic changes. Physicians
should maintain a high suspicion for acute coccidioidomycosis, especially
for persons with a flu-like illness who live in or have visited endemic-disease
areas.
Diphtheria
During 2001, two probable diphtheria cases were reported to CDC. Both patients
had membranous pharyngitis. The first was a man aged 59 years from Montana.
A specimen for culture was not obtained from this patient. The second patient
was a woman aged 19 years from Michigan. Although a throat swab culture
from this patient did not yield Corynebacterium diphtheriae, a
weakly positive Taqman polymerase chain reaction test result was
obtained from the membranous tissue. Neither patient had a history of recent
travel or had contact with international or local visitors. Both patients
survived.
Encephalitis, Arboviral
In 2001, epizootic and epidemic West Nile virus (WNV) activity continued in
the United States, and geographic limits of reported viral activity extended
to western Arkansas and southern Florida (1). WNV-infected birds,
mosquitoes, or horses were detected in 27 states and the District of Columbia;
16 of these states had not previously reported WNV activity. In Florida,
dead infected birds were collected as late as December 26, suggesting the
potential for winter transmission in southern regions. An unprecedented
equine WNV epizootic occurred in Florida and Georgia and resulted in 511
reported equine cases. Culex ( Cx. pipiens, Cx. restuans, and Cx. salinarius) mosquitoes
were again the most commonly identified mosquito vectors of WNV. WNV was
also detected in several human-feeding mosquito species (Cx. nigripalpus,
Ochlerotatus sollicitans, Oc. tainiorhynchus, and Coquillitidia perturbans),
raising concerns about increased human risk in areas where these species
are common (2,3). A total of 66 human cases of WNV disease were
reported from 39 counties in 10 states (64 patients with WNV meningoencephalitis
and two persons with uncomplicated WNV fever).
In 2001, 79 human cases of St. Louis encephalitis (SLE) were reported from Arizona (n = 1), Arkansas (n = 2), Louisiana, (n = 71), and Texas (n = 5). Epidemic SLE activity in Louisiana was centered in the city of Monroe (4).
Escherichia coli, enterohemorrhagic
In 2001, the National Notifiable Diseases Surveillance System expanded surveillance
of Escherichia coli O157:H7 to include other serogroups of Shiga
toxin-producing E. coli under the inclusive name enterohemorrhagic E.
coli (EHEC). Surveillance categories for EHEC include 1) EHEC O157:H7;
2) EHEC, serogroup non-O157; and 3) EHEC, not serogrouped.
During 2001, 3,485 cases of EHEC infection were reported from 50 states, Guam and Puerto Rico. These cases included 3,294 due to EHEC O157:H7, 171 due to EHEC, serogroup non-O157, and 20 due to EHEC that were not serogrouped. Approximately 50% of stools are tested for E. coli O157, and few stool specimens are tested in a way that would identify other Shiga toxin-producing E. coli (1). The number of cases reported for EHEC should be interpreted as an underestimate in a maturing surveillance system.
Healthy cattle are the main animal reservoir for E. coli O157:H7 and other Shiga toxin-producing E. coli, and they harbor the organism as part of the bowel flora. Most reported outbreaks are caused by contaminated food or water. However, direct transmission from animals and their environment to humans in settings such as petting zoos, open farms, and animal exhibits represents a growing public health concern (2).
Gonorrhea
During 2001, a total of 361,705 cases of gonorrhea were reported (rate: 128.53/
100,000). The 2001 rate was similar to rates for 2000 (129.04/100,000),
1999 (132.32/ 100,000), and 1998 (131.89/100,000) (1) and has
remained stable among men and women. Nevertheless, increases have been
observed in some areas among men who have sex with men (2). Decreased
susceptibility to the fluoroquinolone antibiotics and azithromycin has
been reported from some regions (3). In 2001, the prevalence
of fluoroquinolone-resistant Neisseria gonorrhoeae infections
increased in California. As a result, fluoroquinolones are no longer advised
for treatment of gonorrhea in Hawaii or California or for infections that
may have been acquired in those states (4).
Haemophilus influenzae, Invasive Disease
Since 1990, when Haemophilus influenzae type b (Hib) conjugate vaccines
were licensed for use in infants beginning at age 2 months, Hib has become
a rare cause of invasive disease (e.g., meningitis) among children aged <5
years in the United States (1). Surveillance information is used to
monitor the effectiveness of immunization programs and vaccines and to assess
progress toward disease elimination. To continue to assess progress toward
the elimination of Hib invasive disease, accurate laboratory information is
essential to correctly identify the serotype of the causative H. influenzae (Hi)
isolate (2). Serotyping Hi by slide agglutination can sometimes be
inaccurate, especially since it is not performed frequently in most laboratories.
Recently, CDC reported discrepancies in Hi slide agglutination serotyping results
obtained by state health department laboratories participating in active surveillance
and those obtained by CDC. In this study, 28 (70%) of 40 Hi isolates that had
been reported as Hib to CDC were actually identified at CDC as nontypeable
Hi (2). Because of these discrepancies, CDC requests state health
department laboratories to send all Hi invasive disease isolates from children
aged <5 years to CDC for testing to reconfirm serotype.
Hansen Disease
A total of 81 Hansen disease cases were reported to CDC through the NNDSS database
from 20 states, Puerto Rico and American Samoa in 2001; three states (California,
Hawaii and New York) accounted for 74% of the total number of cases reported.
In contrast, 110 Hansen disease cases were reported to the National Hansen
Disease Program from 27 states and Puerto Rico in 2001; six states (Texas,
New York, Louisiana, Washington, Florida and California) accounted for
71% of the total number of cases reported. These data suggest that the
annual number of cases in the United States may not be declining and underscore
the need for coordination between the multiple surveillance systems as
well as the need to continue to identify and treat patients with Hansen
disease.
Hantavirus Pulmonary Syndrome
During 2001, a total of 11 cases of hantavirus pulmonary syndrome (HPS) were
confirmed in eight states through the Hantavirus Pulmonary Syndrome National
Surveillance System and Registry. Three (27%) cases were fatal. This is
the lowest number of annual cases reported since the disease was recognized
in 1993. Previously, the average number of cases per year was 34 (range:
22-48). As of December 31, 2001, a total of 313 cases have been confirmed
in 31 states, including 32 cases that were retrospectively identified back
to 1959. Hantaviruses are rodent borne, and human infection most commonly
occurs through inhalation of virus particles from infectious rodent droppings,
urine, or saliva. Preventing exposure to rodent hosts remains the most
effective way of preventing morbidity and mortality from HPS because treatment
for the disease is largely supportive (1).
Hemolytic Uremic Syndrome, Postdiarrheal
During 2001, the sixth year of national reporting, 28 states reported 202 cases
of postdiarrheal hemolytic uremic syndrome (HUS). The median age of patients
was 5 years (range: <1-79), and 66% were female. Illness was seasonal,
with 43% of cases occurring from June through September. Although the number
of reported cases in 2001 decreased compared with 2000 (249 cases), it
was greater than in 1999 (181 cases); thus, a trend is not possible to
determine. At least five states, the District of Columbia, and two territories
did not list HUS as a notifiable disease in 2000, contributing to substantial
underreporting.
Postdiarrheal HUS is a life-threatening illness characterized by hemolytic anemia, thrombocytopenia, and renal injury. In the United States, most cases are caused by infection with Escherichia coli O157:H7; some are caused by other Shiga toxin-producing E. coli (1,2).
Hepatitis A
Hepatitis A vaccine is recommended for persons at increased risk of acquiring
hepatitis A (e.g., illegal drug users, men who have sex with men [MSM])
and also for children in states and counties that have historically had
consistently elevated rates of hepatitis A (1). After routine
childhood vaccination was recommended, the overall hepatitis A rate has
declined steadily, and in 2001 it was the lowest yet recorded (4.0/100,000).
Because hepatitis A rates tend to vary from year to year and from region
to region, continued monitoring of hepatitis A incidence is needed to determine
whether this low rate is due to routine immunization or natural variability
in infection rates. However, declines in rates have been greater among
children and in the states where routine childhood vaccination is recommended,
suggesting an impact of childhood vaccination. Despite declining overall
rates, some states reported increasing rates in 2000-2001. In several states,
these increases were related to outbreaks occurring among high-risk adults,
including MSM, and cases among adults in high-risk groups represent an
increasing proportion of reported cases nationwide. For example, cases
among MSM increased from 4% (1990) to 8% (1995) to12% (2000).
Hepatitis B
During 2001, a total of 7,843 acute hepatitis B cases were reported, representing
a > 60% decrease since 1990 (21,102 cases). Surveillance data are being
used to monitor the impact of the national strategy for eliminating hepatitis
B virus (HBV) infection. Healthy People 2010 objectives call for
a 75%-90% reduction in the national incidence of hepatitis B among adults
(baseline: 15-24 cases/100,000), a 99% reduction among children aged 2-18
years (baseline: 945 cases/year), and a 75% reduction in the number of
perinatal HBV infections (baseline: 1,682 infections/year) (1).
The effect of routine infant and adolescent vaccination can already be
seen in the declining rate of disease among persons aged <19 years.
In contrast, the continued high incidence among persons in other risk groups
for which vaccination is recommended, e.g., injection drug users and persons
engaging in high-risk sexual behaviors, indicates that programs for reaching
these populations need to be developed or strengthened.
Hepatitis C; Non-A, Non-B
Cases of hepatitis C reported to CDC are considered unreliable because 1) no
serologic marker for acute infection exists, and 2) most health departments
do not have the resources to determine if a positive laboratory report
for hepatitis C virus (HCV) infection represents acute infection, chronic
infection, repeated testing of a person previously reported, or a false-positive
result (1). Historically, the most reliable national estimates
of acute disease incidence have come from sentinel surveillance. After
adjusting for underreporting and asymptomatic infections, the annual number
of new infections has decreased >80% since 1989 to 25,000 cases in 2001
(CDC, unpublished data, 2002). Because surveillance for acute hepatitis
C can be used to evaluate the effectiveness of prevention efforts and identify
missed opportunities for prevention, efforts are under way to help states
establish and improve surveillance.
HIV Infection, Adult*
Persons with HIV infection are living longer without progressing to AIDS. As
a result, AIDS incidence is decreasing and no longer provides the most
accurate information on the HIV epidemic. Recommendations for implementing
national HIV case surveillance were published in December 1999, and the
revised surveillance case definition became effective January 1, 2000 (1).
By December 31, 2001, 37 areas had laws or regulations requiring confidential reporting by name of adults/adolescents with confirmed HIV infection. Nine areas (Washington, DC, Hawaii, Illinois, Kentucky, Maryland, Massachusetts, Puerto Rico, Rhode Island, and Vermont) had implemented a code-based system to conduct case surveillance for HIV infection. Other areas (Delaware, Maine, Montana, Oregon, and Washington) had implemented a name-to-code system to conduct HIV infection surveillance: names are collected initially and later are converted to codes. Data on cases of HIV infection from those areas conducting code-based or name-to code systems are not included in this report pending evaluations demonstrating acceptable performance under CDC guidelines and the development of methods to report such data to CDC (2).
Trend analysis is possible by examining data from the 25 states** that have continually conducted HIV surveillance since 1994. These 25 states represent 24% of all AIDS cases diagnosed in the United States. During 1994-2000, HIV infection was diagnosed in 128,813 persons from the 25 states. The number of persons newly diagnosed each year with HIV infection declined steadily during 1994-1997. From 1997 through 2000, case counts have been stable in all age, race/ethnicity and HIV exposure categories. The largest declines were observed in the following groups: persons aged 25-44 years, men who have sex with men, and injection-drug users. The majority (55%) of persons with newly diagnosed HIV in these 25 states were black non-Hispanic, and 36% were white non-Hispanic. Because persons with newly diagnosed HIV infections include those who may have had previously unrecognized infections for a long time, these data do not represent incident infections. However, the stability in the number of infections diagnosed each year during the latter part of the 1990s and the small declines in the proportion of persons presenting with AIDS indicate that improvements in the targeting of HIV counseling and testing are needed to facilitate earlier diagnoses. Early diagnosis is a critical factor in ensuring that infected persons are linked to effective treatment and prevention services to reduce further transmission and improve quality of life (3).
*For information on AIDS.
**Alabama, Arizona, Arkansas, Colorado, Idaho, Indiana, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Nevada, New Jersey, North Carolina, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Utah, Virginia, West Virginia, Wisconsin, and Wyoming.
HIV Infection, Pediatric
As of December 2001, 39 areas conducted name-based surveillance for HIV infection
among children aged <13 years. In 2001, 543 children whose infection
had not progressed to AIDS and 175 children who had AIDS were reported (1).
These states also received reports of perinatally exposed children who
required follow-up with health-care providers to determine their HIV infection
status.
In 2000, an estimated 6,075-6,422 infants were born to
HIV-positive mothers in the United States. Of these infants, an estimated
280-370 were infected with HIV, representing a decline of >80% from
the 1991 peak of 1,760 estimated HIV-positive U.S. births (2).
Declines in perinatal HIV infections have been attributed to the use
of zidovudine to reduce perinatal HIV transmission (3) and
to nationwide efforts to implement routine, voluntary prenatal HIV
testing for all pregnant women (4). Continued declines in
perinatal HIV infections may be difficult to sustain unless new HIV
infections
in women of childbearing age are reduced.
Lyme Disease
During 2001, 17,029 cases of Lyme disease were reported, most from the northeastern
and north-central United States. During 1991-2000, the reported incidence
of Lyme disease nearly doubled (1). LYMErix®, the Lyme disease
vaccine produced by GlaxoSmithKline Pharmaceuticals, was removed from the
market in February 2002 and is no longer available. CDC promotes community-based
Lyme disease prevention using strategies aimed at reducing vector tick
densities and preventing human infection and is currently funding such
projects in Connecticut, Massachusetts, New Jersey, and New York.
Malaria
During 2001, 1,544 malaria cases were reported in the United States. Most cases
were imported, with twice as many cases occurring among U.S. residents
traveling to malarious areas as occurred among foreign residents immigrating
to or visiting the United States (1). Although the number of reported
cases was similar to 2000 (1,591) (2), the annual number of cases
has increased during the past 15 years. This increase was likely caused
by increases in both international travel (3) and immigration (4),
as well as the spread and intensification of antimalarial drug resistance
globally (5).
Measles
A total of 116 confirmed measles cases were reported in 2001; cases occurred
in 22 states. Fifty-four of the cases were internationally imported, and
exposure to these cases resulted in 25 additional cases. Twelve other cases
had virologic evidence of importation (i.e., genotypic analysis of measles
viruses indicated an imported source). The remaining 25 cases were classified
as unknown source cases because no link to importation was detected. The
majority of confirmed measles cases (61 cases) occurred in persons aged ≥ 20
years; 29 cases occurred in persons 5-19 years, and 26 occurred in children
aged <5 years. Ten outbreaks, ranging in size from 3 to 14 cases, accounted
for 49% of cases (n = 57). All 10 outbreaks were linked to international
importation; nine had an epidemiologic link to imported cases and one had
virologic evidence of importation.
Meningococcal disease
Rates of meningococcal disease have been relatively stable in the United States.
A total of 2,333 cases were reported in 2001, of which 1,931 were confirmed,
77 probable, seven suspected, and 318 of unknown case status. Serogroup
information was reported for 33% of cases, and serogroup Y accounted for
33% of those reported. Most other cases were caused by serogroup B (32%)
or serogroup C (27%). Although rates of meningococcal disease are usually
highest among children aged <1 year, 55% of cases in
2001 occurred among persons aged ≥ 18 years.
Using the technology applied to the development of Haemophilus influenzae type b (Hib) conjugate vaccines, several companies are in the final stages of developing and testing meningococcal conjugate vaccines with various serogroup-specific formulas and in combination with other antigens for licensure in the United States (1). Three serogroup C meningococcal conjugate vaccines were licensed and integrated into routine childhood immunization in the United Kingdom in 2000; early results confirm 85%-95% efficacy in infants, toddlers and teenagers (2) and suggest herd immunity.
Mumps
Because of the recommendation of two doses of Measles/Mumps/Rubella vaccine
and its high coverage rate in the United States, mumps is at record low
levels. During the 1990s, mumps cases declined substantially, from 5,292
reported cases in 1990 to 266 reported cases in 2001, meeting the Healthy
People 2000 objective of <500 cases per year (1).
Pertussis
During 2001, a total of 7,580 cases of pertussis were reported. Of these, 22%
occurred among infants aged <6 months, who were too young to have received
the recommended three doses of diphtheria and tetanus toxoids and acellular
pertussis (DTaP) vaccine; 3% occurred among children aged 6-11 months;
13% among preschoolaged children (i.e., those aged 1-4 years); 10% among
children aged 5-9 years; 30% among persons aged 10-19 years; and 22% among
persons aged ≥ 20 years.
Since 1995, the coverage rate with ≥ 3 doses of a pertussis-containing vaccine has been >94% among U.S. children aged 19-35 months (1). Since 1980, the number of reported cases of pertussis in infants aged <7 months and in adolescents and adults has increased markedly in some states (2). The reasons for this rise are unknown but could include increased awareness of pertussis among health-care providers, increased use of more sensitive diagnostic tests, better reporting of cases to health departments, and possibly an increase in circulating pertussis. In contrast, the incidence of reported pertussis among children aged 7 months to 9 years has not increased markedly and suggests protection against pertussis. Adolescents and adults can become susceptible to disease because vaccine-induced immunity is believed to wane approximately 5-10 years after pertussis vaccination.
Rubella
Because of the success of the U.S. rubella vaccination program, rubella is
at a record low level, with 23 reported cases in 2001. Rubella now mostly
occurs among adults born in countries that do not have routine rubella
vaccination programs or that have only recently implemented such programs.
In 2000 and 2001, 10 mothers of the 11 children with reported congenital
rubella syndrome were foreign-born Hispanics.
Salmonellosis
A total of 40,495 salmonellosis cases were reported in 2001, an 11% decrease
from 46,831 cases in 1995. Salmonella isolates are reported through
the Public Health Laboratory Information System by serotype (1).
Of >2,000 known Salmonella serotypes, the three most commonly
reported in 2001 were S. Typhimurium, S. Enteritidis, and S. Newport; these
accounted for 50% of isolates reported. During the 5-year period 1997-2001,
the number of S. Newport isolates increased from 5% to 10% of all reported Salmonella isolates.
The increasing number of S. Newport infections in the United States is concurrent with the emergence and rapid dissemination of multidrug-resistant strains of S. Newport with resistance to at least nine antimicrobial drugs. Some strains are also resistant to third-generation cephalosporins such as ceftriaxone, which may be used to treat serious infections. Several outbreaks caused by multidrug-resistant S. Newport have been investigated, including one in which raw or undercooked ground beef was implicated (2).
Shigellosis
Shigella sonnei infections continue to account for approximately
75% of shigellosis in the United States. Prolonged, communitywide
outbreaks of S. sonnei infections that are transmitted in
child care centers and other settings where maintenance of good hygienic
conditions requires special care account for much of the problem (1).
In 2001, one such outbreak in Ohio and Kentucky accounted for several
hundred laboratoryconfirmed infections. S. sonnei can also
be transmitted through contaminated foods and through water used
for drinking or recreational purposes (2,3). Recent evidence
suggests that S. sonnei infections are increasing among
men who have sex with men (4).
Streptococcal Disease, Invasive, Group A
(including streptococcal toxic-shock syndrome)
During 2001, 1,147 cases of invasive group A streptococcal (GAS) disease were
reported from nine states (California, Colorado, Connecticut, Georgia, Maryland,
Minnesota, New York, Oregon, and Tennessee) through the Active Bacterial Core
Surveillance (ABCs) project under CDC's Emerging Infections Program (1).
Based on these 1,147 cases, CDC estimates that approximately 9,930 cases of
invasive GAS disease (rate: 3.5/100,000) and 1,350 deaths occurred nationally
during 2001. Disease incidence was highest among children aged <1 year (5.5/100,000)
and adults aged ≥ 65 years (9.9/100,000). Streptococcal toxic-shock syndrome
and necrotizing fasciitis accounted for approximately 5.9% and 6.7% of invasive
cases, respectively. The overall case-fatality rate among persons with invasive
GAS disease was 13.2%.
In 2002, CDC published recommendations for the control of invasive group A streptococcal disease among household contacts of persons with invasive GAS infections and for responding to postpartum and postsurgical infections. These recommendations are based on routine surveillance data, studies of the epidemiology of subsequent invasive GAS infections among household contacts of case-patients and postpartum and postsurgical GAS clusters, and studies of the effectiveness of chemoprophylactic regimens for eradicating carriage (2).
Streptococcus pneumoniae, Invasive,
Drug-Resistant
In 2001, the ABCs project of CDC's Emerging Infections Program (1) collected
information on invasive pneumococcal disease, including drug-resistant Streptococcus
pneumoniae, in nine states (California, Colorado, Connecticut, Georgia,
Maryland, Minnesota, New York, Oregon, and Tennessee). For the first time,
the proportion of pneumococcal isolates that were drug resistant was lower
in the current year than reported in the previous year. Of the 3,418 S.
pneumoniae isolates collected in 2001, 9.7% exhibited intermediate resistance
to penicillin (minimum inhibitory concentration [MIC] 0.1-1 µg/mL), and
15.6% were fully resistant (MIC ≥ 2 µg/mL); in 2000, 9.8% were
intermediate and 17.1% were fully resistant (2). For cefotaxime, 10.5%
of all isolates had intermediate resistance and 5.7% were fully resistant in
2001, compared with 9.8% of all isolates with intermediate resistance and 7.5%
fully resistant in 2000. For erythromycin,
19.4% were resistant in 2001 versus 21.3% in 2000. Approximately one in six
(16.9%) isolates had reduced susceptibility to at least three classes of drugs
commonly used to treat pneumococcal infections, a decline from approximately
one fifth (18.9%) of isolates in 2000.
In February 2000, the Food and Drug Administration licensed a pneumococcal conjugate vaccine for use in infants and young children. In October 2000, the Advisory Committee on Immunization Practices issued recommendations for use of the vaccine in children aged <5 years (3). Among isolates from children aged <5 years reported to ABCs during 2001, 63.9% of all strains (n = 587) and 75.9% of strains not susceptible to penicillin (n = 199) were serotypes included in this 7-valent vaccine.
Streptococcus pneumoniae, Invasive, <5
Years
Invasive Streptococcus pneumoniae infection in children aged <5
years was reportable in 28 states and the District of Columbia in 2001. Of
these 29 jurisdictions with mandated reporting, only 11 states and the District
of Columbia reported cases. The incidence rate in these reporting areas was
13.3/100,000, which is lower than the rate of 39.7 cases/100,000 population
estimated from data collected through the Active Bacterial Core Surveillance
(CDC, unpublished data).
Syphilis, Congenital
During 2001, a total of 441 cases of congenital syphilis were reported (rate:
11.1/100,000 live births). Like primary and secondary syphilis, the rate
of congenital syphilis has declined sharply in recent years, from a peak
of 107.3/100,000 in 1991 (1). The continuing decrease in the rate
of congenital syphilis likely reflects the substantial reduction in the
rate of primary and secondary syphilis among women that has occurred in
the last decade. Congenital syphilis persists in the United States because
a substantial number of women do not receive syphilis serologic testing
until late in their pregnancy or not at all. This lack of screening is
often related to absent or late prenatal care (2).
Syphilis, Primary and Secondary
During 2001, a total of 6,103 primary and secondary syphilis cases were reported.
From 1990 to 2000, the primary and secondary syphilis rate declined 90%,
from 20.34/100,000 to 2.12/100,000. The overall 2001 rate (2.17/100,000)
is a 2% increase from the 2000 rate, which was the lowest since reporting
began in 1941 (1) and the first annual increase since 1990. The
2001 primary and secondary syphilis rate reflects a 15.4% increase among
men but a 17.7% decrease among women. This disparity between
men and women, observed across all racial and ethnic groups, along with reported
outbreaks of syphilis among men who have sex with men (MSM) in large urban
areas, suggests that increases in syphilis are occurring among MSM. Rates also
remain disproportionately high in the South and among non-Hispanic blacks. (2,3).
Tetanus
In 2001, 37 cases of tetanus were reported from 15 states. Four (10.8%) cases
were among persons aged <25 years, 19 (51.4%) cases were among persons
aged 25-59 years, and 14 (37.8%) cases were among persons aged ≥ 60
years. The percentage of cases among persons aged 25-59 years has increased
during the last decade; previously, most cases were among persons aged ≥ 60
years (1). One neonatal case with an atypical presentation of
tetanus was reported from California. The mother of the infant was foreign
born and had an unknown vaccination status. The infant recovered after
30 days of hospitalization. Six (16.7%) of the non-neonatal cases were
fatal.
Tuberculosis
During 2001, a total of 15,989 cases (rate: 5.6/100,000 population) of tuberculosis
(TB) were reported to CDC from the 50 states and the District of Columbia,
representing a 2% decrease from 2000 and a 40% decrease from 1992, when
the number of cases and the case rate most recently peaked in the United
States (1). In 1991, 73% of reported cases were among U.S.-born
persons (rate: 8.2/100,000), and 27% were among foreign-born persons (33.9/100,000).
In comparison in 2001, there was an equal distribution (50%) in the number
of TB cases among these two groups (case rates: 3.1/100,000 for U.S.-born
persons and 26.6/100,000 for foreign-born persons) (1).
Despite the decrease in case rate among foreign-born persons during the past decade, half of the TB cases in the United States in 2001 occurred in this population, and the case rate was eight times greater in this population than among U.S.-born persons. To address the high rate, CDC is collaborating with public health partners to implement TB control initiatives among recent international arrivals and residents along the border between the United States and Mexico and to strengthen TB programs in countries with a high incidence of TB disease (2). CDC has recently updated its comprehensive national action plan to reflect the alignment of its priorities with the Institute of Medicine report (3) and to ensure that priority prevention activities are undertaken with optimal collaboration and coordination among national and international public health partners (4).
Typhoid Fever
In 2001, typhoid fever was diagnosed in 368 persons in the United States. Despite
the availability of two effective vaccines, NNDSS reports 350-450 cases
each year. Approximately 80% of these cases occur among persons who report
international travel during the 6 weeks before illness. Persons visiting
friends and relatives in their country of origin appear to be at high risk (1).
In many areas of the world, Salmonella Typhi strains have acquired
resistance to multiple antimicrobial agents, including ampicillin, chloramphenicol,
and trimethoprim-sulfamethoxazole (1). S. Typhi outbreaks
in the United States are generally small in size, but they can cause significant
morbidity and are often foodborne, warranting thorough investigation (2).
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