Am. J. Trop. Med. Hyg., 88(3), 2013, pp. 552–558
Copyright © 2013 by The American Society of Tropical Medicine and Hygiene
A Foodborne Outbreak of Brucellosis at a Police Station Cafeteria, Lima, Peru
Karina Roma ´n, Rosa Castillo, Robert H. Gilman, Maritza Caldero ´n, Aldo Vivar, Manuel Ce ´spedes, Henk L. Smits,
Paolo Mele ´ndez, Eduardo Gotuzzo, Humberto Guerra, Ryan C. Maves, Michael A. Matthias,
Joseph M. Vinetz,* and Mayuko Saito
Department of Molecular and Cellular Sciences, Faculty of Sciences, and Laboratory of Research and Development,
Universidad Peruana Cayetano Heredia, Lima, Peru ´; United States Naval Medical Research Unit No. 6 (NAMRU-6), Lima, Peru ´;
Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland; Asociacio ´n Bene ´fica PRISMA,
Lima, Peru ´; Hospital Nacional Arzobispo Loayza, Peru ´; Instituto Nacional de Salud, Lima, Peru ´; KIT Biomedical Research,
Royal Tropical Institute/Koninklijk Instituut voor de Tropen (KIT), Amsterdam, The Netherlands;
Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia University, Lima, Peru ´;
Division of Infectious Diseases, Department of Internal Medicine, Naval Medical Center, San Diego, California;
Division of Infectious Diseases, Department of Medicine, University of California San Diego, San Diego, California
epidemiological contexts. Within the context of an ongoing brucellosis surveillance project, an outbreak at a Peruvian
police officer cafeteria was discovered, which led to active surveillance (serology, blood culture) for additional cases
among 49 police officers who had also eaten there. The cohort was followed up to 18 months regardless of treatment or
symptoms. Active surveillance estimated the attack rate at 26.5% (13 of 49). Blood cultures from four cases were
positive; these isolates were indistinguishable using multiple locus variable number tandem repeat analysis. This investi-
gation indicates the importance of case tracking and active surveillance for brucellosis in the context of potential
common source exposure. These results provide rationale for public health investigations of brucellosis index cases
including the bioterrorism-related dissemination of Brucella.
Brucella melitensis is highly infectious for humans and can be transmitted to humans in a number of
Brucellosis is a zoonotic infection of livestock, primarily
cattle, goats, and sheep, and is transmitted to humans by
consumption of their raw milk, unpasteurized dairy products,
direct contact with infected animals, or secretions from repro-
ductive organs.1,2Brucella melitensis infections in humans
most commonly occur in the context of eating unpasteurized
goat (or sheep) milk or cheese products; B. melitensis is
almost entirely the cause of human brucellosis identified in
Peru. In clinical microbiology laboratories, Brucella is well
known to be highly infectious (with an infective dose of as
few as 10 organisms by inhalation) and, being an occupational
health risk, prevention of occupationally acquired brucellosis
requires high levels of biological safety to protect labora-
tory and other workers.3–9Brucellosis most often presents
as a subacute, recurring fever (undulant fever) or may have
diverse clinical expressions including meningitis, endocar-
ditis, hepatitis, splenic abscess, arthritis, epididymo-orchitis,
spondylitis, focal brain lesions, and other chronic complica-
tions including difficult-to-diagnose chronic fatigue-like syn-
dromes.1Because Brucella spp. are so infectious by the
inhalational route they are considered potential agents of
bioterrorism and are classified as Category B select agents
in the United States.
Brucellosis became established as a focus of endemic coun-
try research in Lima, Peru from the 1980s onward. In this
context, a prospective, referral-based surveillance and diag-
nostics development project was carried out in Lima, Peru
from 2007 to 2009 that identified new B. melitensis antigens
useful for serological diagnosis of brucellosis10–12and allowed
for a larger study catchment area than previously feasible.
Recent years have seen a significant reduction in brucellosis
cases in Peru as reported by the Ministry of Health Office of
General Epidemiology (unpublished data). This decline is
thought to be a result of goat vaccination campaigns and other
animal public health programs. Human brucellosis still con-
tinues to occur in this country and more than 800 cases were
reported as recently as 2008 with the majority reported from
the Lima metropolitan area13where almost half of the
country’s population lives. Many small, family-based goat
farms are located around Lima. Goat white cheese, “queso
fresco,” prepared from unpasteurized milk and traded from
distantly located farms is commonly sold in markets in Lima,
and is an important source of Brucella infection. In Peru,
brucellosis affects all socio-economic classes because the con-
sumption of goat’s milk products is common. Commercial
white cheese production is supposed to be regulated to be made
from pasteurized milk to prevent transmission of Brucella
spp. or other bacterial infection to humans; this is true in large
formal markets but not in informal sales venues such as small
farms that sell directly to street and informal market vendors.
White cheese is often eaten with bread or mixed with other
ingredients in the sauces of typical local dishes such as “Papa
a la huancaı ´na” without cooking.
In December 2007, an outbreak of brucellosis affected offi-
cers at a police station in Lima as became manifest by several
index cases reported by a local Lima hospital. Three months
after the first case, all officers at this police station were
serologically screened for brucellosis and additional cases
were identified. The outbreak was suspected to be caused by
consumption of food made of unpasteurized goat white cheese
served in meals at the police station’s cafeteria. The results
of this investigation show the importance of contact tracing
for cases of brucellosis and reinforce the need to regulate
unpasteurized goat milk products.
Outbreak context and subjects. At the end of December
2007, a group of police officers working at a station in Lima,
Peru reported symptoms of joint pain, muscle pain, and exces-
sive sweating. By February 2008, 13 of 60 officers working in
*Address correspondence to Joseph M. Vinetz, 9500 Gilman Drive,
Mail Code 0640, La Jolla, CA 92093. E-mail: email@example.com
the same office were diagnosed with acute brucellosis based
on clinical symptoms, signs, and positive screening serology
(positive Rose Bengal [RB] agglutination test). No further
laboratory testing at a local health post or police hospital
(Hospital de Policia, Lima) was done. Only those presenting
to a local health clinic were initially evaluated. In March 2008,
four officers originally diagnosed with brucellosis from this
station presented to Hospital Nacional Arzobispo Loayza in
Lima to seek testing for brucellosis because of persisting
symptoms after prior treatment (Figure 1). All were serologi-
cally positive, and two were clinically suspected to have active
disease based on symptoms, which prompted active screening
of all the officers at the police station in early April 2008.
Standard practice by the officers included two work shifts
daily and three meals provided in a cafeteria. Sixty officers,
including the 13 previously diagnosed with brucellosis, were
invited to be screened for brucellosis. The screening was
conducted at the police station.
Ethical approval. This study was approved by the Institu-
tional Review Boards of Universidad Peruana Cayetano
Heredia, Hospital Nacional Cayetano Heredia, University of
California San Diego, Asociacio ´n Bene ´fica PRISMA, Hos-
pital Nacional Arzobispo Loayza, and United States Naval
Medical Research Unit No. 6 (NAMRU-6). A project nurse
discussed involvement in the project in detail with each
potential subject, and all participants provided written
Screening tests for brucellosis. The standard RB test14–17
(Instituto Nacional de Salud, Lima, Peru) and a lateral flow
assay (LFA) for detection of specific immunoglobulin M
(IgM) and IgG antibodies18were used for screening; a posi-
tive result on either test was sufficient to be considered posi-
tive. Comprehensive clinical and demographic data including
personal history of brucellosis and white cheese consumption
were recorded. Details of food consumption at the cafeteria
were not queried because of the introduction of recall bias.
Confirmatory testing for brucellosis. Screening serolog-
ical tests were confirmed using the Brucella tube aggluti-
nation test (TAT) (definitive positive, ³ 1/160) and the
2-mercaptoethanol (2-ME) Brucella agglutination test (defin-
itive positive, ³ 1/20).19
Blood cultures to attempt Brucella isolation were done on
patients with positive screening serologies, using both the lysis
centrifugation method20and the BD BACTEC system (Becton
Dickinson and Company, Franklin Lakes, NJ).21A positive
culture was considered definitive proof of brucellosis.
Follow-up. Confirmatory serological tests and blood cul-
ture were repeated at 3, 6, and 12 months after completion
of treatment. Patients diagnosed with brucellosis in this study
were referred to their own physician for treatment and clini-
Brucella genotyping. Culture isolates were genotyped
independently by laboratories at the Universidad Peruana
Cayetano Heredia and NAMRU-6 (Lima, Peru) using multi-
ple locus variable number tandem repeat analysis (MLVA-16
locus).22,23Isolates obtained during follow-up were tested using
the previously described five polymorphic loci in Peruvian
B. melitensis biovar 1 isolates (Bruce 07, 09, 16, 18, and 42).23
A 100 bp and a 20 bp molecular marker ladder (Invitrogen,
Carlsbad, CA) were used to estimate MLVA band sizes; the
B. melitensis strain 16 M was used as the control.
Statistics. Serology and culture results were compared
between the symptomatic and asymptomatic groups. Fre-
quencies of background factors (consumption of white cheese
outside of the working place and time shift of the work)
were compared between seropositive and negative groups.
The c2tests were performed using STATA 8 (StataCorp,
College Station, TX).
Study participants. Forty-nine (45 men, 4 women, median
age: 44 [23–56]) of 60 officers (82%) working at the police
station were screened in April 2008, 3 months after the first
indication of the outbreak (Figure 1). Eleven officers, includ-
ing three previously diagnosed cases did not participate in
the study, because they either had left the service or declined
for personal reasons, therefore they were excluded from the
analysis. Ten (20.4%) out of 49 officers who participated in
our study reported having been diagnosed with brucellosis
between December 2007 and February 2008 (Table 1) before
the active surveillance began.
Diagnosis of brucellosis. Three new patients in addition to
the already identified 10 patients, out of 49 participants, were
officers from December 2007 to April 2008.
Distribution of cases with brucellosis in police station
Characteristics of participants screened in Lima, Peru police station—
Screened N = 49
Median age (years)
Brucellosis previously diagnosed in:
Nov 2007 or before (before the outbreak)
Dec 2007–Jan 2008 (outbreak)
Presence of symptoms at screening
FOODBORNE BRUCELLOSIS OUTBREAK, LIMA, PERU
RB screening test positive (Table 2). Three of 13 officers with
a positive screening test had a positive blood culture and
confirmatory serology, which was the basis of identifying
three new patients; 9 of 13 had positive quantitative serology
(TAT or 2-ME) and negative culture. One blood culture pos-
itive case had positive lateral flow testing for IgG but negative
TAT and 2-ME tests. Thus, all 13 individuals with positive
screening tests were confirmed to have active or past brucel-
losis infection either by blood culture or quantitative serology
tests. Comparison of all symptomatic and asymptomatic par-
ticipants showed that positivity of each screening test was
significantly associated with being symptomatic (Table 2).
There was no difference, however, in positivity of blood cul-
ture or confirmatory serological tests between asymptomatic
and symptomatic cases when compared only in individuals
screened as positive (Table 2).
These data indicate that 3 of 13 cases had never been pre-
viously diagnosed with brucellosis but were detected by active
case finding. Two of these cases had clinical symptoms typical
of brucellosis; one remained asymptomatic (Figure 2). Nine of
10 officers identified by a positive RB test were confirmed by
quantitative serology except one who only had a positive LFA
and a positive blood culture.
Identification of presumed point source of infection.
Because all officers consumed their meals at the cafeteria with
a limited menu, we presumed that most of the participants ate
the same meals if their time shifts were the same. Regarding
the consumption of dairy products outside the police station,
11 of 13 seropositive participants (84.6%) reported eating
white cheese at the supermarket and 12 (92.3%) consumed
“Papa a la huancaina” at restaurants and/or at home (Table 3).
None reported eating unpasteurized goat whitecheese. Regard-
less, the rates of positive responses for these questions were
similar in both seropositive and negative participants (Table 3).
Notably, of the 13 seropositive cases, 11 were officers of the
first shift (the odd days of the month) and two were officers
of the second shift (the even days of the month). The propor-
tion of the seropositive cases tended to be larger in the offi-
cers of first shift (11 of 31; 35.5%) than that in the second shift
(2 of 18; 11.1%), although it did not reach statistical signifi-
cance (P = 0.06) (Table 3). All participants received meals at
the police station cafeteria that were prepared by a contrac-
tor. The participants reported that no family member was
known to be affected by brucellosis during or after the out-
break and throughout the duration of follow-up.
Follow-up. Clinical features of the 13 patients of bru-
cellosis were typical of the disease (Table 4). Three newly
Laboratory results of participants screened in police station—April 2008*
P value Total Symptomatic†Asymptomatic
Rose Bengal test positive
Lateral flow assay
# Screening positive‡
N = 49 (%)
N = 23 (%)
N = 26 (%)
TAT ³ 1: 160
Blood culture positive
# Brucellosis diagnosedk
*TAT = tube agglutination test; 2-ME = 2-mercaptoethanol agglutination test.
†At time of screening, there were 23 symptomatic subjects, manifesting as fever (5), sweats (9), myalgia (11), and arthralgia (18).
‡Any of the screening tests positive.
§Applied only for participants with positive screening results.
¶One culture sample became positive after 3 months from the treatment. It was from an asymptomatic subject (follow-up sample).
kAny of TAT, 2-ME, or culture positive, including active and inactive.
N = 13 (%)
N = 10 (%)
N = 3 (%)
in Lima, Peru, December 2007 to April 2008.
Incidence of brucellosis in 60 police station officers
Consumption (intake) of dairy food outside police station and
working shift reported during the outbreak
Positive N = 13Negative N = 36
n (%)n (%)
Consumption (intake) of dairy outside of the working station
Any white cheese
Non-pasteurized white cheese
Any goat cheese
Papa a la Huancaı ´na
Group 1 (N = 31)
Group 2 (N = 18)
11 (84.6)30 (83.3) 0.915
*P values are from c2test used for comparison of two groups.
ROMA´N AND OTHERS
diagnosed brucellosis cases received a full 45-day course of
standard antibiotic treatment (doxycycline plus rifampin).
Among the 10 previously diagnosed and treated cases, four
were retreated (Table 4). Twelve of 13 cases were followed
for 18 months after the outbreak. On follow-up, two cases
relapsed after treatment; one was identified by blood cul-
ture, the other by an increased titer in the serological tests
(TAT and 2-ME). Both cases had symptoms consistent with
brucellosis, including headache, myalgia, arthralgia, and
insomnia. The other 10 cases appeared clinically cured after
completing treatment and had gradual declining titers with-
out reporting any symptoms of brucellosis throughout the
follow-up period. The remaining patient (who was not fol-
lowed) was contacted more recently and denied relapse of
Genotyping of Brucella isolates. All four Brucella isolates
had an identical MLVA type (Figure 3), which is the most
frequently reported genotype among human B. melitensis
biovar 1 isolates isolated in the period 2003–2007 from patients
To our knowledge, there are no reports of a work-associated
outbreak of brucellosis affecting people not directly dealing
with animal products or bacteria. Previous reports focused on
family,24–27laboratory, or animal-associated risk factors for
infection.3–9Food-borne outbreaks have been reported in
families or neighborhoods as a result of the ingestion of goat
white cheese distributed to households.6,24–28It is known that
patients with Brucella infection may well be asymptomatic
despite being proven by culture to be bacteremic.29,30None-
theless, our present report reinforces the need for active
surveillance and contact tracing after apparent point source
outbreaks given the subclinical or early cases that are not
identified in a timely manner because of non-specific symp-
toms. This outbreak also reinforces the need to consider dif-
ferent cultural issues regarding potential food point exposures
in brucellosis transmission. Our characterization here of occu-
pation-related brucellosis reflects the practice among police
officers in Peru to share meals, whereas brucellosis acquisi-
tion in the occupational context typically refers to agricultural
or veterinary exposure.
It is most likely that food ingested at the police station
cafeteria was responsible for transmission of B. melitensis.
This assumption is not only based on the monomorphic
MLVA findings in the few isolates obtained from cases, but
also based on finding additional cases associated primarily
with one working shift. None of the household members of
the cases developed brucellosis during the 18 months of our
follow-up. In previous studies, however, a high rate of family
cases has been found in household members of brucellosis
patients,24,25,27,28suggesting that the infection was not acquired
at home in this outbreak.
Clinical features of 13 patients with brucellosis after police station common source outbreak*
During the outbreak 3 months after the outbreak
culture Treatment regimen
1 (42/F)Yes Doxy + Rif Arthralgia
Rif + Gent + Azi 6 weeks pregnancy. Seronegative 12 months
14-day treatment during outbreak. On screening,
culture positive, asymptomatic, declined
treatment. After 3 months (July 2008),
developed fever, arthralgia, and received
treatment. Seronegative at 12 months
Seronegative 6 months after treatment.
2 (37/M)YesDid not recall None
1° Not treated
2° Doxy + Rif
3 (50/M) No NoSweats, headache,
Doxy + Rif
4 (45/M) No No
1° Doxy + Rif
2° Doxy + Rif
Relapse with positive culture without symptoms
3 months after 1st treatment. Seronegative
at 18 months after 2nd treatment.
Retreated for relapsed symptoms 5 months
after 1st treatment after outbreak.
Seronegative at 12 months after 2nd treatment.
Seronegative 7 months after the outbreak.
Seronegative 19 months after the outbreak.
Doxy + Rif + Gent 12-month follow-up ended with positive serology
but no symptoms.
Not treatedSeronegative 15 months after the outbreak.
5 (47/M)Yes Doxy +RifFever, myalgia, arthralgia
2° Doxy + Amik
Doxy + Rif
Doxy + Rif
Headache, lumbar pain
Weight loss, headache,
arthralgia, lumbar pain
Weight loss, headache,
Sweats, headache, myalgias,
arthralgia, lumbar pain
Weight loss, myalgias,
lumbar pain, diarrhea
Sweats, general malaise,
9 (42/M) YesDoxy + Rif
Doxy + RifSeronegative after the treatment until completion
of follow-up after 12 months.
Seronegative 15 months after the outbreak.11 (46/M)YesDoxy + Rif +
Doxy + Rif
Not treatedSeronegative 9 months after the outbreak.
13 (39/M)YesDoxy + Rif
Not treatedFollowed at another hospital so no follow-up
data available. No symptoms 18 months after
*Ami = Amikacin; Azi = Azithromycin; Doxy = Doxycycline; Gent = Gentamicin; Rif = Rifampin; Trime-Sulfa = Trimethoprim-Sulfamethoxazole.
FOODBORNE BRUCELLOSIS OUTBREAK, LIMA, PERU
Some localPeruvian cuisine, “Papa a la huancaina,” “Ocopa,”
and “Chupe, prepared with unpasteurized goat white cheese
might have been the source of the acquired infection. It was
known that these dishes were served to all before the out-
break and have characteristics of being eaten without the
consumer knowing whether unsafe ingredients were present
in the food. However, our interviews were performed 3 months
after the outbreak, making dietary history imperfectly reliable
in this study.
Of 60 officers at the police station, 13 (21.7%) sought
medical attention before our study and were diagnosed with
brucellosis. After 3 months, we identified three additional
cases. This outbreak resembles a previous study of laboratory-
acquired Brucella abortus infection followed by sequential
active serological tests, which showed that most of the infected
individuals were asymptomatic when they seroconverted with
time to seroconversion varying from 6 weeks to 5 months8; a
similar range of the incubation period was reported in the case
of B. melitensis infection.9
Although regular serological surveillance is done on lab-
oratory workers handling Brucella, active testing has not
been reported in the setting of potential food exposures.
Several studies of family-based outbreaks have reported
asymptomatic seropositive or bacteremic cases found during
Because the incubation period of human brucellosis is
highly variable, our study reinforces the clinical need to seri-
ally test people at risk for Brucella infection following poten-
tial or known exposures, even if asymptomatic. For laboratory
exposure, it is recommended to test weekly or semiweekly for
the first 3 months using standard serologies, and once a month
thereafter for 3 to 9 months after exposure. Prophylaxis after
assessment of exposure risk is carried out typically using
doxycycline 200 mg/day plus rifampin 600 mg/day for at least
3 weeks.4Insufficient evidence exists to support administering
antibiotic prophylaxis after possible ingestion of Brucella-
containing foods, and the culture or molecular analysis of
food for Brucella is difficult and not feasible. The data pro-
vided here would support a recommendation to follow
patients with serological tests and blood cultures to detect
subclinical infections or later manifestations of brucellosis.
In our patient cohort, 2 of 13 (15%) relapsed after 3 and
6 months despite completing standard antimicrobial therapy.
These relapsed patients were treated with rifampin and doxy-
cycline for an additional 6 weeks according to the recommen-
dations by the World Health Organization (WHO).9Relapse
rates have been reported to range from 10% to 20%1,4and
were similar to ours.Follow-up after treatment is recommended
as previously described.4
Part of this study was retrospective, with some important
limitations. First, the standard serological tests that we used to
identify brucellosis cases, although reported to be > 90% sen-
sitive and specific,2,14,31,32nonetheless are imperfect; the gold
standard diagnosis is isolation of the organism in culture. The
reason that the RB and lateral flow assay were chosen as
screening tests in this study was to take advantage of the
relatively high sensitivity of these tests to enhance the chances
of capturing cases. The RB test used to screen enrolled sub-
jects could have over-estimated cases because previous infec-
tion unrelated to this outbreak may have led to seropositivity.
There is a theoretical risk of the Brucella agglutination tests
cross-reacting with antibodies to Yersinia enterocolitica,
Francisella tularensis, and Escherichia coli O157, which in the
present context is not clinically or epidemiologically consis-
tent. The lateral flow assay used as a screening test in this
study—which detects IgM and IgG antibodies to Brucella
LPS—would potentially have the same limitation; the pro-
longed incubation time of brucellosis can lead to both diag-
nostic titers of IgM and IgG antibodies at the time of
presentation, and, in the case of this epidemiological investi-
gation, at the time of screening. However, previous studies
have shown that even in endemic regions the LFA IgM/IgM
test has a sensitivity and specificity of ~> 96%, even when
used in endemic areas.18,33,34The performance of screening
* M:Marker; 1, Case 1; 2, Case 2; 3, Case 3; 4, Case 4 (Relapsed); CN, Negative control; Bm, Brucella melitensis 16M strain.
Multiple locus VNTR genotyping of Brucella melitensis strains from four isolates obtained from April 2008 to August 2008.*
ROMA´N AND OTHERS
agglutination tests (either the RB or slide agglutination test)
occasionally is inferior to the tube agglutination test, which
has different incubation times and conditions.35Confirmatory
serologies performed in this study included the tube aggluti-
nation test (with a 1 of 160 titer cutoff) and the 2-ME test
(that differentiates IgM from IgG antibodies, indicating acute
infection) to enhance the specificity of testing; previous stud-
ies from Peru and elsewhere have shown these criteria to be
strongly suggestive of a new episode of brucellosis.19,27Tests
to detect non-agglutinating anti-Brucella antibodies using the
Coombs or BrucellaCapt test were not used in this study,
which may have led to an underestimation of cases. Overall,
the combination of serological tests done in this study served
to enhance both the sensitivity and specificity of active case
finding among the potentially affected population. Another
limitation of this partially retrospective study is that written
laboratory test results of the officers affected at the beginning
of the outbreak (December 2007) were not available, there-
fore we had only verbal information from them regarding
their prior diagnosis and treatment of brucellosis. Detailed
information was not sought regarding the frequency of inges-
tion of high risk foods at the cafeteria because of the need
to avoid recall bias. Nor could we obtain food distribution
sources from the cafeteria contractor. Culture samples of the
meals served at the cafeteria were not obtained to look for
Brucella, which numerous studies have shown to be highly
challenging and largely unrewarding. Another limitation of
this study is that differentiating infecting B. melitensis strains
remains challenging. The standard MLVA panel for Brucella
uses 16 loci and thus the monomorphic results may not dif-
ferentiate subtle differences; in this study only five loci used
have proven useful for differentiating among strains.23Whole
genome sequencing would be necessary to investigate more
detailed differences between infecting strains. Finally, there
is a remote possibility that the identified relapses may have
been new infections.
The clinical pathogenesis of brucellosis depends on multi-
ple, mostly unknown interactions between pathogen and host
that combine to prolong the time from exposure to clinical
manifestations. Active case finding and follow-up after poten-
tial point-source foodborne exposures, as indicated by sen-
tinel cases should be carried out despite the absence of
symptoms. An unanswered question is whether prophylactic
treatment is beneficial for those who shared the dishes during
the outbreaks. Finally, food safety monitoring and regulated
pasteurization of dairy products are necessary for the control
of brucellosis. Improved monitoring will require reliable cul-
ture or bacterial antigen detection methods for food tracking
and the active screening of milk products and carrier animals
in areas where brucellosis persists.
Received September 30, 2012. Accepted for publication November
Published online February 4, 2013.
Acknowledgments: We thank A. Leo ´n and B. Torres, laboratory and
clinical staff of the Hospital Nacional Arzobispo Loayza for their
collaboration and A. Paredes, S. Cuba, C. Montesinos, G. Zegarra,
P. Garcı ´a, and R. Cabrera for their support of this investigation. We
are grateful to Paula Maguin ˜a, Staff Research Associate at the
University of California San Diego for her scientific, compliance
coordination, and logistical contributions critical for the successful
completion of this work.
Financial support: This study was funded by a Cooperative Agree-
ment from the United States Public Health Service, National Insti-
tutes of Health, National Institute of Allergy and Infectious Diseases
Disclosure: R. Castillo is an employee of the U.S. Government and R.
Maves is a military service member. This work was prepared as part
of their official duties. Title 17 U.S.C. §105 provides that “Copyright
protection under this title is not available for any work of the United
States Government.” Title 17 U.S.C. §101 defines a U.S. Government
work as a work prepared by a military service member or employee of
the U.S. Government as part of that person’s official duties.
Disclaimer: The views expressed in this article are those of the authors
ment of the Navy, Department of Defense, or the U.S. Government.
Universidad Peruana Cayetano Heredia, Department of Micro-
biology, Faculty of Sciences and Philosophy, Lima, Peru ´, E-mails:
firstname.lastname@example.org and email@example.com. Paolo Mele ´ndez,
A.B. PRISMA - Biomedical research unit, Lima, Peru, E-mail:
firstname.lastname@example.org. Rosa Castillo, NAMRU-6, Microbiology,
Lima, Peru ´, E-mail: Rosa.Castillo@med.navy.mil. Robert H.
Gilman, Johns Hopkins University, International Health, Baltimore,
MD, E-mail: email@example.com. Aldo Vivar, Hospital Macional
Arzobispo Loayza — Medicine, Lima, Peru ´, E-mail: avivar@prisma
.org.pe. Manuel Ce ´spedes, Instituto Nacional de Salud, Diagnostic
Laboratories, Lima, Peru ´, E-mail: firstname.lastname@example.org.
Henk L. Smits, Royal Tropical Institute, Kit Biomedical Research,
Amsterdam, The Netherlands, E-mail: email@example.com. Eduardo
Gotuzzo and Humberto Guerra, Universidad Peruana Cayetano
Heredia, Instituto de Medicine Tropical Alexander von Humboldt,
Lima, Peru ´, E-mails: firstname.lastname@example.org and humberto.
email@example.com. Ryan C. Maves, United States Naval Medical
Research Unit No. 6 (NAMRU-6), Lima, Peru ´, current affiliation:
Division of Infectious Diseases, Department of Internal Medicine,
Naval Medical Center, San Diego, CA, E-mail: Ryan.Maves@med
.navy.mil. Michael A. Matthias, UC San Diego — Medicine, La Jolla,
CA, E-mail: firstname.lastname@example.org. Joseph M. Vinetz, Division of
Infectious Diseases, Department of Medicine, University of
California San Diego, San Diego, CA, E-mail: email@example.com.
Mayuko Saito, A.B. PRISMA — Biomedical Research Unit, Lima,
Peru ´, and Universidad Peruana Cayetano Heredia — Department
of Microbiology, Faculty of Sciences and Philosophy, Lima, Peru ´,
and, Division of Infectious Diseases, Department of Medicine, Uni-
versity of California San Diego, San Diego, CA, E-mail: msaitop@
addresses:KarinaRoma ´n and Maritza Caldero ´n,
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