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Morbidity and Mortality Weekly Report
MMWR / March 23, 2012 / Vol. 61 / No. 11 185
immigrants to the United States (7). As more high-TB burden
countries adopt these technical instructions, screening and
treating immigrants should improve. Persons screened overseas
and found to have LTBI should receive preventive TB treat-
ment upon arrival in the United States. A new, shorter regimen
for LTBI requiring just 12 once-weekly drug administrations
has been recommended by CDC and might result in better
adherence to LTBI treatment in foreign-born and U.S born
populations (8,9).
Approximately 81% of TB cases in 2011 had known HIV
status at TB diagnosis. This increase (66.3% in 2010) is
attributed to increased reporting from selected regions. The
American Thoracic Society and the Infectious Disease Society
of America recommend that all TB patients be counseled and
tested for HIV (10).
This analysis is limited to reporting provisional TB cases
and case rates for 2011. Case rates are based on estimates of
population denominators from either 2010 or 2011. CDC’s
annual TB surveillance report will provide final TB case rates
based on updated denominators later this year.
Progress toward TB elimination in the United States will
require ongoing surveillance and improved TB control and
prevention activities. Sustained focus on domestic TB control
activities and further support of global TB control initiatives
is important to address persistent disparities between non-
Hispanic whites and racial/ethnic minorities and between
U.S born and foreign-born persons.
Acknowledgments
State and local TB control officials.
References
1. CDC. Reported tuberculosis in the United States, 2010. Atlanta, GA:
US Department of Health and Human Services, CDC; 2011. Available
at http://www.cdc.gov/tb/statistics/reports/2010/default.htm. Accessed
February 21, 2012.
2. CDC. Decrease in reported tuberculosis cases—United States, 2009.
MMWR 2010;59:289–94.
3. US Census Bureau. Current estimates data. Available at http://www.
census.gov/popest/data/national/totals/2011/index.html. Accessed
February 2, 2012.
4. CDC. A strategic plan for the elimination of tuberculosis in the United
States. MMWR 1989;38(No. S-3).
5. Hill AN, Becerra JE, Castro KG. Modelling tuberculosis trends in the
USA. Epidemiol Infect 2012:1–11.
6. Cegielski JP, Griffith DE, McGaha PK, et al. Eliminating tuberculosis,
one neighborhood at a time. Am J Public Health 2012 (In press).
7. CDC. CDC immigration requirements: technical instructions for
tuberculosis screening and treatment. Using cultures and directly
observed therapy. US Department of Health and Human Services, CDC;
2009. Available at http://www.cdc.gov/immigrantrefugeehealth/pdf/
tuberculosis-ti-2009.pdf. Accessed February 16, 2012.
8. Sterling TR, Villarino ME, Borisov AS, et al. Three months of rifapentine
and isoniazid for latent tuberculosis infection. N Engl J Med 2011;
365:2155–66.
9. CDC. Recommendations for use of an isoniazid-rifapentine regimen
with direct observation to treat latent Mycobacterium tuberculosis
infection. MMWR 2011;60:1650–3.
10. CDC. Treatment of tuberculosis. American Thoracic Society, CDC, and
Infectious Diseases Society of America. MMWR 2003;52(No. RR-11).
What is already known on this topic?
Although tuberculosis (TB) has been on the decline in the
United States since 1993, an increasing proportion of cases has
been observed among the foreign-born. Racial and ethnic
minorities have represented a higher proportion of cases
among the U.S born.
What is added by this report?
Provisional 2011 surveillance data indicate a TB case rate of 3.4
cases per 100,000 persons, which is the lowest rate since 1993.
For the first time since current reporting began in 1993, Asians
have become the most widely represented racial/ethnic group
among TB cases, even though case rates also have declined in
this group. Reporting of human immunodeficiency (HIV) status
at diagnosis has improved in the most recent reporting year,
and HIV infection among TB cases is at an all-time low.
What are the implications for public health practice?
Continued awareness and surveillance of TB is needed despite
the decline. Initiatives to improve awareness, testing, and
treatment of latent infection and TB disease in minorities and
foreign-born populations should facilitate progress toward the
elimination of TB in the United States.
Morbidity and Mortality Weekly Report
186 MMWR / March 23, 2012 / Vol. 61 / No. 11
Despite the overall decline in tuberculosis (TB) incidence in
the United States to a record low (1), outbreaks of TB among
homeless persons continue to challenge TB control efforts. In
January 2010, public health officials recognized an outbreak of
TB after three overnight guests at a homeless shelter in Illinois
received diagnoses of TB disease caused by Mycobacterium
tuberculosis isolates with matching genotype patterns. As
of September 2011, a total of 28 outbreak-associated cases
involving shelter guests, dating back to 2007, had been rec-
ognized, indicating ongoing M. tuberculosis transmission. The
subsequent investigation found that all patients were homeless
and had been overnight shelter guests. Excess alcohol use was
common (82%), and two bars emerged as additional sites of
potential transmission. Patients with outbreak-associated TB
were treated successfully for TB disease. To prevent future cases
of TB, public health officials are implementing a program to
offer 12 once-weekly doses of isoniazid and rifapentine under
direct observation for treatment of latent tuberculosis infec-
tion (LTBI) (2) in this high-risk population. Although the
United States has made progress toward TB elimination, this
outbreak demonstrates the vulnerability of homeless persons
to outbreaks of TB, highlighting the need for aggressive and
sustained TB control efforts.
Initial Investigations
In April 2007, a man aged 55 years received a diagnosis of
sputum smear–positive TB disease caused by an M. tuberculosis
isolate with a genotype pattern* not documented previously in
Kane County, Illinois. The man had been a frequent overnight
guest at a Kane County facility that provided short-term shel-
ter each night for approximately 180 persons whose housing
situation was unstable. Subsequent case finding among other
guests and staff members at the shelter identified no additional
cases. In October 2009 and January 2010, two additional cases
with the index patient’s TB genotype pattern were identified
among overnight shelter guests, alerting public health officials
to a potential outbreak.
By March 2010, three additional cases with the outbreak
genotype pattern had been identified among overnight shelter
guests, leading county and state officials to request on-site
epidemiologic assistance from CDC. Because all patients had
been guests at the shelter, CDC recommended on-site case
finding among guests and staff members at the shelter. The
average length of stay at the shelter for guests was 2 weeks.
During contact investigations and four mass screenings at the
shelter during May 2010–June 2011, public health officials
evaluated 386 persons recently exposed to a person with an
infectious outbreak case, finding six (2%) additional TB cases.
During April 2007–July 2011, a total of 25 cases with the
outbreak genotype pattern were identified (Figure). All patients
had stayed overnight at the shelter, raising concern about ongo-
ing transmission. The local health department concurrently
identified approximately 10 TB cases each year unrelated to
the outbreak, and the increased load during 2010 and 2011
led officials to request on-site assistance from CDC again in
September 2011.
Subsequent Investigation
For the September 2011 investigation, a confirmed outbreak
case was defined as TB disease having the outbreak genotype
pattern diagnosed since April 2007 in a county resident. A sus-
pected outbreak case was TB disease without an M. tuberculosis
isolate available for genotyping (i.e., clinical disease), diagnosed
since April 2007 in a county resident who had an epidemiologic
link to a patient with a confirmed outbreak case. Investigators
reviewed each eligible case to estimate infectious periods (3),
identify potential sites of transmission, and determine epi-
demiologic linkages. Sources included medical records and
interviews with patients or proxies, health department staff
members, and shelter staff members.
As of September 23, 2011, a total of 28 outbreak cases had
been identified (Table 1). Nearly one third of cases (29%)
were detected through investigation-related activities (Figure,
Table 1). Excluding one child, the median age was 49 years
(range: 19–64 years) (Table 1). The one patient who had not
slept in the men’s sleeping area had known social connections
(e.g., through alcohol consumption) to a patient who had
slept in the men’s sleeping area. Overall, 24 (86%) patients
had connections through shared activities at the shelter or
through shared behaviors (e.g., alcohol use at bar A). Of 25
with infectious pulmonary TB, 20 (80%) patients were pres-
ent overnight at a location other than the shelter during their
infectious periods, and the other five (20%) spent time at sites
other than the shelter during the daytime.
To better understand the transmission dynamics, investi-
gators conducted a case-control study. Because all outbreak
Tuberculosis Outbreak Associated with a Homeless Shelter —
Kane County, Illinois, 2007–2011
* Spoligotype 777777757760771 and 12-locus mycobacterial interspersed
repetitive unit–variable number tandem repeat pattern 223326153324.
Morbidity and Mortality Weekly Report
MMWR / March 23, 2012 / Vol. 61 / No. 11 187
patients had been overnight guests of the homeless shelter
who had, with one exception, slept in the men’s sleeping area,
eligible case-patients were defined as men confirmed to be part
of the outbreak (i.e., TB with the outbreak genotype) who had
stayed overnight at the shelter at least once during August 2006
(i.e., the beginning of the index patient’s infectious period)
through July 2011 (i.e., the end of the last infectious period
among men with confirmed outbreak TB). Controls were men
who had stayed overnight at the shelter at least once during the
same period but who had completed evaluations to exclude TB
disease and LTBI (i.e., had a negative test for infection) and
were asymptomatic at the time of interview.
Of the 25 patients eligible as case-patients, 17 (68%) enrolled
in the case-control study. Of 72 men eligible as controls, 24
(35%) were located, and 23 (96%) met the inclusion criteria; all
23 enrolled. Although the small sample size limited the ability
to detect statistically significant associations, longer duration
of stay at the shelter, excess alcohol use, and occasional or
frequent attendance at certain bars (A or B) had nonstatisti-
cally significant associations with being a case-patient (odds
ratio ≥1.9) (Table 2). Because only 35% of eligible men could
be located, selection bias of controls might have affected the
outcome of this case-control study.
Public Health Interventions
In close collaboration with shelter staff members, public
health officials have provided housing support, food, trans-
portation, and treatment for TB disease by directly observed
therapy to 24 of the 28 patients (i.e., excluding two patients
who received care from other health jurisdictions, one who
died, and one who was never located); all of these 24 patients
with TB disease had completed or were continuing treatment as
of December 2011. Supportive resources alone (i.e., excluding
costs of health-care services) to provide successful treatment for
these 24 patients with TB disease cost $204,500. Programmatic
resources were not available to permit extension of these ser-
vices to the 146 persons who had been exposed at the shelter
and did not have TB disease but did have LTBI; 10 (7%) had
completed LTBI treatment as of September 2011. Based on
the subsequent investigation and case-control study, future
case finding and LTBI treatment efforts will prioritize persons
who slept in the men’s area at the shelter and who socialized
together at certain sites in the community. County and state
officials have been working with the shelter to implement
administrative control measures to reduce transmission at the
shelter, including TB symptom screening upon admission to
the shelter for overnight guests and evaluation for TB disease
and infection for guests within 10 days of initial stay and annu-
ally. Although three additional outbreak cases were identified
after the subsequent investigation, as of March 5, 2012, no
further cases had been identified since December 2011.
Reported by
Claire Dobbins, MS, Kate Marishta, MPH, Paul Kuehnert, MS,
Kane County Health Dept; Michael Arbisi, MS, Elaine Darnall,
Craig Conover, MD, Illinois Dept of Public Health. Julia
FIGURE. Number of outbreak cases of tuberculosis (TB), by date of diagnosis — Kane County, Illinois, April 2007–September 2011
* One patient received a diagnosis of TB during care unrelated to symptoms. The remainder received a diagnosis of TB during examination for TB-related symptoms.

0
1
2
3
4
5
6
7
No. of cases
S
S
S
Detected during patient’s care unrelated to investigation activities*
Suspected cases (i.e., cases without genotyping information)
Detected through investigation-related activities
Date of diagnosis
S
Jan–Mar
Apr–Jun
Jul–Sep
Oct–Dec
Jan–Mar
Apr–Jun
Jul–Sep
Oct–Dec
Jan–Mar
Apr–Jun
Jul–Sep
Oct–Dec
Jan–Mar
Apr–Jun
Jul–Sep
Oct–Dec
Jan–Mar
Apr–Jun
Jul–Sep
2007 2008 2009 20112010
Morbidity and Mortality Weekly Report
188 MMWR / March 23, 2012 / Vol. 61 / No. 11
Howland, MPH, CDC/CSTE Applied Epidemiology Fellow;
Krista Powell, MD, Sandy Althomsons, MPH, Sapna Bamrah,
MD, Denise Garrett, MD, Maryam Haddad, MSN, Div of TB
Elimination, National Center for HIV/AIDS, Viral Hepatitis,
STD, and TB Prevention, CDC. Corresponding author:
Krista Powell, duf8@cdc.gov, 404-639-8120.
Editorial Note
Despite progress toward TB elimination (1), this outbreak
demonstrates the vulnerability of persons affected by homeless-
ness to outbreaks of TB, highlighting the need for aggressive
and sustained TB control efforts. Outbreaks among persons
experiencing homelessness are difficult to control, in part
because of the challenges in finding and locating contacts and
providing treatment for LTBI (4,5), as illustrated in this out-
break. Excess alcohol use and congregation in crowded shelters,
which frequently are associated with homeless persons, increase
their risk for TB (6–8). Of patients in this outbreak, 80%
spent time at sites other than the shelter during their infectious
periods, and attendance at certain bars had a nonstatistically
significant association with being a case-patient, suggesting
transmission was not limited to the shelter. Therefore, out-
breaks of TB among homeless populations can pose a risk to
entire communities.
TABLE 2. Comparison between outbreak-associated tuberculosis case-
patients and control subjects — Kane County, Illinois, 2007–2011
Characteristic
Case-
patients
(n = 17)
Controls
(n = 23)
Odds
ratio
(95%
confidence
interval)*No. (%) No. (%)
Age group (yrs)
≥47 10 (59) 10 (43) 1.9 (0.5–6.6)
<47 7 (41) 13 (57)
Duration of stay at shelter (days)
≥250 11 (65) 9 (39) 2.9 (0.8–10.5)
<250 6 (35) 14 (61)
Reported work history
Yes 7 (41) 15 (65) 0.7 (0.1–1.4)
No 10 (59) 8 (35)
Smoked tobacco ≥1 yr
Yes 16 (94) 15 (65) 8.5 (1.0–77.6)
No 1 (6) 8 (35)
Use of excess alcohol
Yes 14 (82) 12 (52) 4.2 (1.0–19.0)
No 3 (18) 11 (48)
Location frequented
Bar A
Occasionally/frequently 12 (71) 9 (39) 3.7 (0.9–14.2)
Never/rarely 5 (29) 14 (61)
Bar B
Occasionally/frequently 6 (35) 5 (22) 1.9 (0.5–8.0)
Never/rarely 11 (65) 18 (78)
Hotel H
Occasionally/frequently 1 (6) 5 (22) 0.2 (0.02–2.1)
Never/rarely 16 (94) 18 (78)
Train station
Occasionally/frequently 10 (59) 13 (57) 1.1 (0.3–3.9)
Never/rarely 7 (41) 10 (43)
Library
Occasionally/frequently 9 (53) 13
(57) 0.9 (0.3–3.1)
Never/rarely 8 (47) 10 (43)
*
All confidence intervals contain the null value of 1.
TABLE 1. Demographic and clinical characteristics and risk factors
of 28 patients with outbreak-associated tuberculosis (TB) — Kane
County, Illinois, April 2007–September 2011
Characteristic No. (%)
Country of birth
United States 25 (89)
Mexico 2 (7)
Other 1 (4)
Race
Black 14 (50)
White 14 (50)
Ethnicity
Non-Hispanic 24 (86)
Hispanic 4 (14)
Homeless status
For <1 yr before diagnosis 28 (100)
For ≥1 yr before diagnosis 23 (82)
Substance use*
Smoked tobacco ≥1 yr 26 (93)
Any substance
†
24 (86)
Excess alcohol 23 (82)
Injected drugs 3 (11)
Noninjected drugs 9 (32)
Medical history
Diabetes 1 (4)
Human immunodeficiency disease infection 3 (11)
Mental illness
§
12 (43)
TB case characteristics
Cavitary disease 11 (39)
Sputum smear–positive disease 13 (46)
Method of case detection
TB contact investigations 8 (29)
Other method
¶
20 (71)
Duration of illness — median days (range)
Infectious period** 162 (36–430)
Hospitalization
††
19 (2–55)
Stay in alternative housing
§§
91 (36–115)
* Within 1 year of TB diagnosis.
†
Not including tobacco. Includes excess alcohol, injected drugs, or noninjected
drugs.
§
An Axis I clinical disorder other than a substance-related disorder, based on
American Psychiatric Association classifications, as documented in a patient’s
medical record or report by a patient or proxy.
¶
One patient received a diagnosis of TB during care unrelated to symptoms.
The remainder received a diagnosis of TB during examination for TB-related
symptoms.

** Estimated using methods recommended by CDC in the Guidelines for the
Investigation of Contacts of Persons With Infectious Tuberculosis:
Recommendations From the National Tuberculosis Controllers Association and
CDC. Not estimated for one pediatric patient and two patients with
extrapulmonary disease without pulmonary disease.

††
Length of stay could not be calculated for six patients, including two patients
missing hospital admission and discharge dates, and four patients missing
discharge dates. The pediatric patient received outpatient treatment.
§§
The pediatric patient did not require housing support from the health
department.
Morbidity and Mortality Weekly Report
MMWR / March 23, 2012 / Vol. 61 / No. 11 189
Organizations that provide shelter and other types of
emergency housing for homeless persons should develop
institutional TB control plans (9). Other strategies to reduce
TB transmission in shelters have included ventilation system
improvements (9). In May 2010, the National Institute
for Occupational Health and Safety conducted an on-site
assessment of the heating, ventilation, and air-conditioning
(HVAC) systems of the shelter associated with this outbreak,
and along with appropriate administrative controls, recom-
mended HVAC renovations to reduce TB transmission at the
shelter. As of March 5, 2012, shelter and public health officials
had secured funding for this renovation project, scheduled to
begin in June 2012.
The first priority in TB control is to find and treat persons
with active TB, but the second is to find and treat persons with
LTBI to avert active cases of TB (9). The standard treatment
for LTBI in the United States has been 9 months of isoniazid,
but adherence rates have been low (approximately 60%), even
in the absence of factors such as homelessness or substance
use. CDC recently published guidelines for a shorter course
LTBI treatment alternative, 12 doses of once-weekly isoniazid
and rifapentine administered under direct observation (2), a
regimen that public health officials in Illinois plan to offer
persons exposed in this outbreak who have LTBI. Although
large populations of homeless persons were not included in
treatment trials (2), the practical advantages of this shorter
regimen suggest the potential to transform the public health
approach to LTBI.
TB outbreaks among homeless persons are resource-inten-
sive, requiring provision of housing and other supportive ser-
vices to patients (as in this outbreak), ongoing outreach, and
TB case finding (7). Because this outbreak occurred during
an economic downturn, available public health resources were
constrained. Local policymakers had reorganized the health
department in November 2010, transferring some health
services to other health entities, reducing the health depart-
ment’s workforce by 50% (10). The dynamics of constrained
resources have required close collaboration among local, state,
and federal officials and the shelter to implement interventions.
The extent to which M. tuberculosis was transmitted among
persons experiencing homelessness in this outbreak provides
a warning about the potential for loss of progress toward TB
elimination if resources are shifted from TB control, particu-
larly among vulnerable populations.
Acknowledgments
Shelter staff members; Sara Boline, MPH, Rita Bednarz, Marcia
Huston, MD, Annette Julien, Mari Pina, Arlene Ryndak, MPH,
Kathy Swedberg, Priya Verma, MD, Jeannie Walsh, Jeanette Zawacki,
Judy Zwart, Kane County Health Dept, Illinois. Regina Gore, Dan
Ruggiero, Div of TB Elimination, National Center for HIV/AIDS,
Viral Hepatitis, STD, and TB Prevention, CDC.
References
1. CDC. Trends in tuberculosis—United States, 2011. MMWR 2012;
61:181–5.
2. CDC. Recommendations for use of an isoniazid-rifapentine regimen
with direct observation to treat latent Mycobacterium tuberculosis
infection. MMWR 2011;60:1650–3.
3. CDC. Guidelines for the investigation of contacts of persons with
infectious tuberculosis: recommendations from the National Tuberculosis
Controllers Association and CDC. MMWR 2005;54(No. RR-15):1–49.
4. Reichler M, Reves RR, Bur S, et al. Evaluation of contact investigations
conducted to detect and prevent transmission of tuberculosis. JAMA
2002;287:991–6.
5. Yun LWH, Reves RR, Reichler MR, et al. Outcomes of contact
investigation among homeless persons with infectious tuberculosis. Int
J Tuberc Lung Dis 2003;7(Suppl 3):S405–11.
6. Oeltmann J, Kammerer JS, Pevzner ES, Moonan PK. Tuberculosis and
substance abuse in the United States, 1997–2006. Arch Intern Med
2009;169:189–97.
7. Haddad MB, Wilson TW, Ijaz K, Marks SM, Moore S. Tuberculosis
and homelessness in the United States, 1994–2003. JAMA 2005;
22:2762–6.
8. Lofy KH, McElroy PD, Lake L, et al. Outbreak of tuberculosis in a
homeless population involving multiple sites of transmission. Int J Tuberc
Lung Dis 2006;10:683–9.
9. CDC. Controlling tuberculosis in the United States: recommendations
from the American Thoracic Society, CDC, and the Infectious Disease
Society of America. MMWR 2005;54(No. RR-12).
10. Kuehnert PL, McConnaughay KS. Tough choices in tough times:
enhancing public health value in an era of declining resources. J Public
Health Manag Pract 2012;18:118–25.
What is already known on this topic?
Despite the recent decline in tuberculosis (TB) incidence in the
United States to a record low, certain populations remain at risk
for TB, including homeless persons.
What is added by this report?
During 2007–2011, a total of 28 persons associated with a
homeless shelter in Illinois received a diagnosis of TB disease.
Mycobacterium tuberculosis isolates were available from 25 of
the 28 patients; all 25 isolates were submitted for genotyping
analysis and found to have matching genotype patterns. This
outbreak demonstrates the association between homelessness
and outbreaks of TB.
What are the implications for public health practice?
Sustained efforts are needed to control TB among homeless
persons. When outbreaks among homeless persons occur,
TB case-finding at sites of transmission is needed to identify
persons for treatment and to interrupt transmission. To prevent
future cases of TB disease, homeless persons should be
prioritized for testing and treatment for latent TB infection,
even in the absence of outbreaks.
Morbidity and Mortality Weekly Report
190 MMWR / March 23, 2012 / Vol. 61 / No. 11
By January 2012, 23 years after the Global Polio Eradication
Initiative (GPEI) was begun, indigenous wild poliovirus
(WPV) transmission had been interrupted in all countries
except Afghanistan, Pakistan, and Nigeria (1,2). However,
importation of WPV into 29 previously polio-free African
countries during 2003–2011 (3,4) led to reestablished WPV
transmission (i.e., lasting >12 months) in Angola, Chad,
Democratic Republic of the Congo (DRC), and Sudan
(although the last confirmed case in Sudan occurred in 2009)
(5). This report summarizes progress toward polio eradication
in Africa. In 2011, 350 WPV cases were reported by 12 African
countries, a 47% decrease from the 657 cases reported in 2010.
From 2010 to 2011, the number of cases decreased in Angola
(from 33 to five) and DRC (from 100 to 93) and increased in
Nigeria (from 21 to 62) and Chad (from 26 to 132). New WPV
outbreaks were reported in 2011 in eight African countries,
and transmission subsequently was interrupted in six of those
countries. Ongoing endemic transmission in Nigeria poses a
major threat to the success of GPEI. Vigilant surveillance and
high population immunity levels must be maintained in all
African countries to prevent and limit new outbreaks.
Methods for Tracking Progress
WPV cases are identified through acute flaccid paralysis
(AFP) surveillance and testing of stool specimens for poliovi-
ruses in World Health Organization–accredited laboratories.
The Global Polio Laboratory Network provides comprehensive
genomic sequencing of WPV isolates, which enables tracing
of the probable origins of viruses imported into previously
polio-free areas (6).*
Polio-Endemic Country
Nigeria. In 2011, Nigeria reported 62 WPV cases (47 WPV
type 1 [WPV1] and 15 WPV type 3 [WPV3]), compared with
21 WPV cases (eight WPV1, 13 WPV3) in 2010 (Table 1).
†

Three foci of WPV transmission were observed: northwestern
states (Kebbi/Sokoto/Zamfara), north central states (Kano/
Katsina/Jigawa), and northeastern states (Borno/Yobe). One
WPV1 case in 2011 followed an importation from Chad.
Countries with Reestablished Transmission
Angola. During 2005–2007, three separate WPV impor-
tations into Angola were traced to WPV from India. WPV1
transmission was reestablished and has persisted since the latest
importation in 2007 (5). In 2011, four WPV1 cases linked
with reestablished transmission were reported in the southern
province of Kuando-Kubango (onset of the most recent case
was March 2011). A fifth WPV1 case with onset in July 2011
in the northern province of Uige resulted from a new importa-
tion from DRC (Tables 1 and 2).
Chad. Reestablished transmission of WPV3, first imported
from Nigeria in 2007 (5) has continued in Chad. Subsequently,
WPV1 transmission was reestablished following a 2010 impor-
tation from Nigeria (Table 2). In 2010, 11 WPV1 cases were
reported in four regions, and 15 WPV3 cases were reported
in seven regions (Table 1).
§
In 2011, 129 WPV1 cases were
reported in 15 regions (onset of the most recent case was in
December 2011), and three WPV3 cases were reported in the
eastern border region of Ouaddai (onset of the most recent
case was March 2011).
DRC. In 2011, 93 WPV1 cases were reported in Kasai
Occidental, Bandundu, Katanga, Bas-Congo, Kinshasa, and
Maniema provinces, compared with 100 WPV1 cases in
2010 reported in the first five provinces (Table 1). Genetic
sequencing has indicated five foci of transmission during
2010–2011. The late 2010–early 2011 Bandundu and Kasai
Occidental outbreaks were related to WPV1 introduced from
northern Angola in 2010 (Table 2). Cases in western Bas-
Congo Province were related to WPV1 circulating in Angola
and Republic of the Congo (ROC). WPV1 that caused the
2010–2011 Kinshasa Province outbreak were imported from
ROC, Angola, and neighboring Bandundu Province, and
the outbreak at the Bas-Congo/Bandundu provincial border
(May–September 2011) was related to virus circulating in
Kinshasa earlier in 2011. From October to December 2011,
confirmed WPV circulation was restricted to Katanga and
Maniema provinces, which had a combined total of 14 cases
in 2011, all related to transmission reestablished in eastern
DRC in 2008 or earlier, following importation from Angola.
Progress Toward Global Polio Eradication — Africa, 2011
§
In 2012, one WPV1 case had been reported as of March 8, compared with 12
WPV1 cases during January 1–March 8, 2011.
* Countries with no evidence of indigenous WPV transmission for >12 months
and subsequent cases determined to be importations by genomic sequencing.
†
In 2012, five WPV1 and one WPV3 cases had been reported as of March 8,
compared with one WPV1 case during January 1–March 8, 2011.
Morbidity and Mortality Weekly Report
MMWR / March 23, 2012 / Vol. 61 / No. 11 191
Countries with WPV Outbreaks
West Africa. During 2010, transmission continued after
2009 WPV1 outbreaks in Mali, Mauritania, and Sierra Leone
(Tables 1 and 2). In 2010, new WPV1 outbreaks occurred in
Liberia, Mali, and Senegal, and new WPV3 outbreaks occurred
in Mali and Niger. The first case in the 2010 WPV3 outbreak
in Mali was confirmed in October 2010; three cases occurred
in 2011, the latest related case in June 2011. In 2011 there were
four WPV1 importations into Niger (from Chad and Nigeria),
and Nigeria (from Chad), resulting in a total of five cases. In
2011, seven WPV3 importations into Cote d’Ivoire (from
Nigeria), Guinea (from Cote d’Ivoire), Mali (from Nigeria
and Cote d’Ivoire), and Niger (from Nigeria) were reported
(Table 2), resulting in a total of 44 cases.
Horn of Africa. In 2011, one WPV1 case was detected in
Nyanza Province in western Kenya (Table 2); the isolate was
most closely related to WPV1 circulating during 2010 in east-
ern Uganda and was distantly related to WPV1 circulating in
northern Kenya during 2009 that was imported from Sudan
(with origin in Nigeria). Genetic sequencing of WPV1 isolates
indicated that undetected transmission occurred during two
periods of at least 8 months each during 2009–2011 in the
Kenya-Uganda border area.
Central Africa. In January 2011, the last WPV1 case was
reported in ROC related to a 2010 outbreak, bringing the
outbreak total to 442 cases. A single WPV1 case was reported
in Gabon in 2011 that was related to the 2010 WPV1 outbreak
in ROC (4). In 2011, Central African Republic reported four
WPV1 cases related to transmission in Chad (Table 2).
Reported by
Polio Eradication Dept, World Health Organization, Geneva,
Switzerland. Global Immunization Div, Center for Global
Health; Div of Viral Diseases, National Center for Immunization
and Respiratory Diseases; Leslie B. Hausman, MPH, Div of
Foodborne, Waterborne, and Environmental Diseases, National
Center for Emerging and Zoonotic Infectious Diseases, CDC.
Corresponding contributor: Katrina Kretsinger,
kkretsinger@cdc.gov, 404-639-6164.
Editorial Note
During 2011, the efforts to eradicate polio in Africa have had
mixed results. Although outbreaks were interrupted within 6
months of confirmation in six of eight countries in 2011, WPV
transmission persisted in Angola, Chad, DRC, and Nigeria,
and the number of WPV cases increased in Chad and Nigeria.
TABLE 1. Reported wild poliovirus type 1 (WPV1) and type 3 (WPV3) cases, by category of polio-affected country — Africa, 2010–2011*
Category/Country
2010 2011
WPV1 WPV3 Total WPV1 WPV3 Total
Polio-endemic country
Nigeria 8 13 21 47 15 62
Countries with reestablished transmission
Angola 33 — 33 5 — 5
Chad 11 15 26 129 3 132
Democratic Republic of Congo 100 — 100 93 — 93
Total 144 15 159 227 3 230
Countries affected by outbreaks
West Africa
Cote d’Ivoire — — — — 36 36
Guinea — — — — 3 3
Liberia 2 — 2 — — —
Mali 3 1 4 — 7 7
Mauritania 5 — 5 — — —
Niger — 2 2 4 1 5
Senegal 18 — 18 — — —
Sierra Leone 1 — 1 — — —
Horn of Africa
Kenya — — — 1 — 1
Uganda 4 — 4 — — —
Central Africa
Central African Republic — — — 4 — 4
Republic of Congo
†
441 — 441 1 — 1
Gabon — — — 1 — 1
Total 474 3 477 11 47 58
Africa overall 626 31 657 285 65 350
* Data as of March 8, 2012.
†
2010 total includes cases with inadequate specimens that were classified as confirmed polio based on their association with the WPV1 outbreak.
Morbidity and Mortality Weekly Report
192 MMWR / March 23, 2012 / Vol. 61 / No. 11
In 2011, after earlier outbreaks, ongoing WPV transmission
was detected in Chad, DRC, Kenya, Mali, and ROC; as of
March 8, 2012, WPV transmission had been interrupted (i.e.,
>6 months since the last case) in Kenya, Mali, and ROC.
Milestones established in the 2010–2012 GPEI Strategic
Plan included stopping WPV transmission 1) following
importation in countries with outbreaks in 2009 by mid-2010,
2) following importation in countries with outbreaks in sub-
sequent years <6 months after confirmation of the outbreak,
3) in countries with reestablished transmission by the end of
2010, 4) in at least two of the four polio-endemic countries
by the end of 2011, and 5) in all countries by the end of 2012
(7). Substantial obstacles have prevented achievement of these
milestones in Africa.
TABLE 2. Outbreaks secondary to importation of wild poliovirus (WPV) type 1 (WPV1) and type 3 (WPV3), by characteristics and category of
polio-affected country — Africa, 2010–2011*
Category/Country
WPV
importation

type
Onset date of first
imported WPV case
Date laboratory
confirmed WPV case
Onset date of most
recent WPV case
WPV origin by
genomic
sequencing
No. WPV
confirmed
cases
2009 outbreaks that carried into 2010
Mauritania WPV1 October 7, 2009 October 29, 2009 Aprilil 28, 2010 Cote d’Ivoire 18
Mali WPV1 November 12, 2009 January 4, 2020 March 30, 2010 Guinea 2
Sierra Leone WPV1 July 15, 2009 August 14, 2009 February 28, 2010 Guinea 12
New outbreaks in 2010
West Africa
Chad WPV1 September, 17, 2010 November 29, 2010 January 9, 2012 Nigeria 141
WPV3 January 6, 2010 February 12, 2010 January 6, 2010 Nigeria 1
Liberia WPV1 March 3, 2010 April 14, 2010 September 8, 2010 Guinea 2
Mali WPV3 September 17, 2010 October 15, 2010 June 23, 2011 Niger 4
WPV1 May 1, 2010 June 30, 2010 May 1, 2010 Mauritania 1
WPV1 March 6, 2010 April 14, 2010 March 6, 2010 Burkina Faso 1
Niger WPV3 March 8, 2010 April 22, 2010 April 1, 2010 Nigeria 2
Senegal WPV1 January 5, 2010 January 18, 2010 April 30, 2010 Mauritania 10
WPV1 January 12, 2010 February 2, 2010 April 7, 2010 Guinea 3
WPV1 February 14, 2010 March 3, 2010 March 28, 2010 Guinea 5
Horn of Africa
Uganda WPV1 September 28, 2010 October 18, 2010 November 15, 2010 Kenya 4
Central Africa
Republic of Congo (ROC)
†
WPV1 September 28, 2010 November 3, 2010 January 22, 2011 Angola 442
Democratic Republic of Congo (DRC) WPV1 November 11, 2010 November 29. 2010 September 29, 2011 ROC 62
§
WPV1 May 25, 2010 June 28, 2010 May 9, 2011 Angola 79
WPV1 July 11, 2010 August 3, 2010 July 11, 2010 Angola 1
WPV1 September 13, 2010 October 15, 2010 September 13, 2010 Angola 1
WPV1 December 19, 2010 January 2, 2010 December 19, 2011 ROC 1
WPV1 August 6, 2010 September 10, 2010 January 25, 2011 Angola 26
New outbreaks in 2011
West Africa
Cote d’Ivoire WPV3 January 27, 2011 April 5, 2011 July 24, 2011 Nigeria 36
Guinea WPV3 May 14, 2011 June 1, 2011 August 3, 2011 Cote d’Ivoire 1
WPV3 July 27, 2011 August 10, 2011 July 27, 2011 Cote d’Ivoire 1
WPV3 August 3, 2011 September 16, 2011 August 3, 2011 Cote d’Ivoire 1
Mali WPV3 February 8, 2011 March 31, 2011 June 10, 2011 Nigeria 3
WPV3 May 8, 2011 June 9, 2011 May 8, 2011 Cote d’Ivoire 1
Niger WPV3 January 19, 2011 March 14, 2011 January 19, 2011 Nigeria 1
WPV1 July 9, 2011 August 24, 2011 December 12, 2011 Chad 1
WPV1 November 17, 2011 December 14, 2011 November 21, 2011 Nigeria 2
¶
WPV1 December 22, 2011 January 19, 2012 December 22, 2011 Nigeria 1
Nigeria WPV1 November 29, 2011 December 21, 2011 November 29, 2011 Chad 1
Horn of Africa
Kenya WPV1 July 30, 2011 August 25, 2011 July 30, 2011 Uganda 1
Central Africa
Angola WPV1 July 7, 2011 October 26, 2011 July 7, 2011 DRC 1
Central African Republic WPV1 September 19, 2011 October 4, 2011 December 8, 2011 Chad 4
Gabon WPV1 January 15, 2011 February 20, 2011 January 15, 2011 ROC 1
* Data as of March 8, 2012.
†
2010 total includes cases with inadequate specimens that were exceptionally classified as confirmed polio based on their association with the WPV1 outbreak.
§
The 62 cases resulted from nine independent importations.
¶
Sequence data pending for most recent case.
Morbidity and Mortality Weekly Report
MMWR / March 23, 2012 / Vol. 61 / No. 11 193
The first milestone was met for 14 of the 15 countries with
outbreaks occurring in 2009. However, transmission persisted
during 2009–2011 in areas of Kenya and Uganda, indicating
gaps in field surveillance quality and population immunity;
these gaps currently are being addressed. Multiple countries
in the Horn of Africa remain at risk for transmission. For
example, civil conflict has prevented vaccination of children
for the last 18 months in south-central Somalia, and displaced
Somali refugees have contributed to additional resource needs
throughout neighboring countries in the Horn of Africa. The
second milestone was met, or is within reach, for all outbreaks
reported during 2010–2011, except for one outbreak in Mali
and two in DRC that persisted >6 months after confirmation.
New outbreaks in 2011 generally were detected early and
interrupted rapidly because of prompt, large-scale responses; in
contrast, the large ROC outbreak in 2010 progressed because
of delayed detection and response (4). The four genetic lineages
of WPV3 identified in the 2011 West Africa outbreaks all were
related to WPV3 found earlier in northern Nigeria and were
detected after prolonged circulation. AFP surveillance systems
in many countries of western, central, and the Horn of Africa
must be improved to meet certification standards (8) to reliably
detect ongoing WPV transmission and to rapidly detect and
respond to new outbreaks.
With reestablished transmission continuing into 2011 in
Angola, Chad, and DRC, GPEI failed to meet the third mile-
stone. Persistent WPV circulation in Angola caused outbreaks
in western DRC during 2010–2011 (returning to northeastern
Angola in 2011). Angola now appears to be on track to inter-
rupt transmission, 7 years after the first WPV importation
from India in 2005 (5). In Chad, importations from Nigeria
resulted in reestablished WPV3 transmission from November
2007 to March 2011 and reestablished WPV1 transmission
since September 2010. All countries with reestablished trans-
mission substantially increased the number of national and
international staff members working on polio eradication in
2011 to address chronic gaps in surveillance and low popula-
tion immunity. Although the refusal of religious communities
to vaccinate children in northern Katanga was brought to
international attention in 2011 and has contributed to the
percentage of children missed during polio supplementary
immunization activities (SIAs), overall SIA quality in this
province has been noted as poor.
Regarding the fourth and fifth milestones, India has not
detected a WPV case since January 2011 and is no longer
considered a polio-endemic country (2). However, setbacks
occurred in 2011 in the three countries where polio remains
endemic (Afghanistan, Pakistan, and Nigeria). Nigeria remains
the only country in Africa that has never interrupted transmis-
sion. CDC and GPEI’s Independent Monitoring Board (9,10)
have indicated that Nigeria and Pakistan pose the greatest risk
to the success of global polio eradication and that the 2012
goal of interruption of WPV transmission everywhere is clearly
in jeopardy.
Multiple polio outbreaks in Africa since 2003 have been
traced to importations from Nigeria (3,4). Interruption of
endemic WPV transmission in Nigeria is critical to success-
fully eradicating polio in Africa. Operational and managerial
challenges to implementing routine immunization services
and high-quality SIAs are the main reasons children remain
unvaccinated and undervaccinated in northern Nigeria, and
these were complicated in 2011 by serious new security chal-
lenges. In a concerted effort with GPEI partners, the Nigerian
government has developed an emergency plan
¶
aimed at restor-
ing the programmatic momentum evident during 2009–2010.
Many innovative approaches to improve microplanning and
implementation are being instituted, as well as those addressing
migrant communities at high risk.
In December 2011, the CDC Emergency Operations Center
was activated to consolidate and reinforce CDC’s polio eradi-
cation activities; other GPEI partners have taken similar steps
to accelerate polio eradication efforts. Together, partners have
taken steps to enhance coordination of their activities, and
have jointly increased technical assistance, accountability, and
performance. In May 2012, the World Health Assembly will
¶
National Primary Healthcare Development Agency. Nigeria eradication
emergency plan – draft; 2012.
What is already known on this topic?
Indigenous wild poliovirus transmission has never been
interrupted in Afghanistan, Nigeria, and Pakistan. During
2003–2011, outbreaks occurred following importation of the
virus in 29 previously polio-free African countries. Before 2010,
Nigeria was the source of most of the outbreaks in other African
countries.
What is added by this report?
In 2011, the Global Polio Eradication Initiative experienced both
successes and setbacks. The number of wild poliovirus cases in
African countries decreased 47% from the number in 2010.
However, transmission continued in Angola, Chad, Democratic
Republic of the Congo, and Nigeria in 2011, and the number of
cases increased in Chad and Nigeria.
What are the implications for public health practice?
Interrupting wild poliovirus transmission in Nigeria is key to the
success of the global initiative, but the goal of global polio
eradication by the end of 2012 is in serious jeopardy. CDC and
polio eradication partners are assisting the remaining polio-
affected countries in Africa by taking urgent steps to enhance
the implementation of polio eradication activities, reach more
children in mass campaigns, and interrupt transmission.
Morbidity and Mortality Weekly Report
194 MMWR / March 23, 2012 / Vol. 61 / No. 11
consider a resolution declaring polio eradication an emergency
for global public health. Urgent action is needed to strengthen
SIA implementation and surveillance in the polio-affected
countries of Nigeria, Chad, and DRC. All other countries in
Africa need to urgently strengthen surveillance systems and
attain high levels of population immunity to reliably detect
WPV and prevent or limit the impact of new outbreaks.
References
1. CDC. Progress toward interruption of wild poliovirus transmission—
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aspx. Accessed March 16, 2012.
3. CDC. Wild poliovirus type 1 and type 3 importations—15 countries,
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