Leptospirosis-associated severe pulmonary hemorrhagic syndrome, Salvador, Brazil.

We report the emergence of leptospirosis-associated severe pulmonary hemorrhagic syndrome (SPHS) in slum communities in Salvador, Brazil. Although active surveillance did not identify SPHS before 2003, 47 cases were identified from 2003 through 2005; the case-fatality rate was 74%. By 2005, SPHS caused 55% of the deaths due to leptospirosis.

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Leptospirosis, a spirochetal zoonotic disease, is increasingly recognized as an important cause of hemorrhagic fever (1-4). The classic presentation of severe leptospirosis, Weil's disease, is characterized by jaundice, acute renal failure, and bleeding. However, the 1995 Nicaragua outbreak raised awareness for leptospirosis as the cause of a severe pulmonary hemorrhagic syndrome (SPHS) (5). This syndrome, first identified in South Korea and People's Republic of China (6), is now reported worldwide (2). SPHS is associated with fatality rates of >50% and in certain settings, has replaced Weil's disease as the cause of death among leptospirosis patients (7-10).

The factors responsible for SPHS and its emergence are not well understood. In Brazil, outbreaks of leptospirosis occur annually in slum communities during seasonal periods of heavy rainfall (11). Although SPHS is a frequently observed manifestation of leptospirosis in Rio de Janeiro and Sao Paulo (7,8,12), the occurrence of SPHS varies according to geographic region. In the city of Salvador (population 2.7 million), active surveillance did not detect SPHS among 1,786 leptospirosis cases identified from 1996 through 2002 (unpub. data). However, in 2003 we identified a patient in whom massive pulmonary hemorrhage and acute respiratory distress syndrome developed; subsequently, the number of cases with similar manifestations unexpectedly increased. We report the investigation of the emergence of SPHS in a setting where it was not previously observed.

The Study

The Oswaldo Cruz Foundation and State Secretary of Health of Bahia have conducted active surveillance for leptospirosis since March 1996 in the metropolitan region of Salvador. According to health secretary protocols, suspected cases are referred to the state infectious disease hospital. The study team consecutively identified case-patients who were admitted to this hospital and met the clinical definition for severe leptospirosis (11). Study participants were enrolled according to informed consent protocols approved by the Oswaldo Cruz Foundation and Weill Medical College of Cornell University. After the first case was identified on May 1, 2003, the study team prospectively identified SPHS from October 2003 through December 2005 by evaluating patients 5 days a week for findings of massive pulmonary hemorrhage (hemoptysis >300 mL or aspiration of fresh blood after endotracheal intubation, which did not clear with suctioning) and respiratory insufficiency (respiratory rate [greater than or equal to] 30 per min or use of supplemental oxygen therapy). Medical records of patients hospitalized between January 2000 and September 2003 were reviewed to identify cases that may not have been previously recognized.

A data-entry form was used to extract information from medical charts. Patients or family members were interviewed to obtain information on demographics and risk exposures in the household and workplace. Blood samples were collected during hospital admission, on day 4 or 5 of hospitalization, and 2 weeks after the initial sample was obtained. Laboratory-confirmed diagnosis of leptospirosis was defined as a 4-fold rise in titer between paired samples or a single titer of [greater than or equal to] 800 in the microscopic agglutination test (MAT) (11) or a positive result on the immunoglobulin M (IgM) ELISA (Bio-Manguinhos, Rio de Janeiro, Brazil) (13). The MAT panel included the 19 reference strains recommended by the World Health Organization (Royal Tropical Institute, the Netherlands) and a clinical isolate, Leptospira interrogans serovar Copenhageni strain Fiocruz L1-130 (11).

Surveillance identified 47 (10%) SPHS cases among 474 patients who met the clinical definition for severe leptospirosis from 2003 through 2005. Review of medical records did not identify an SPHS case before 2003. Of 47 SPHS cases, 37 (79%) had a confirmed diagnosis of leptospirosis. Single and paired samples were not obtained for testing from 2 and 8 of the 10 unconfirmed SPHS case-patients, respectively, all of whom died during hospitalization.

Among the 47 SPHS case-patients, 7 (15%) and 20 (42%) had pulmonary hemorrhage and respiratory insufficiency, respectively, at the time of hospitalization (Table 1). Pulmonary hemorrhage was identified in 19 (40%) patients only after endotracheal intubation (Table 2). Except for respiratory insufficiency, hemoptysis, and oliguria, SPHS case-patients had similar clinical manifestations to those of non-SPHS patients at the time of initial evaluation (Table 1). However, 7 (15%) and 16 (34%) of the 47 SPHS patients did not have signs of jaundice and acute renal insufficiency, respectively. Respiratory failure developed in all SPHS patients. Acute lung injury was documented in 25 (76%) of the 33 patients for whom arterial blood gas measurements were obtained (Table 2). Although patients received supportive care with mechanical ventilation (94%), dialysis (53%), and packed erythrocyte transfusion (60%), case-fatality rate for SPHS was 74% and significantly higher than that (12%) for non-SPHS leptospirosis (Table 1). By 2005, SPHS was the cause of 55% of the deaths among leptospirosis patients (Figure).

The annual incidence of SPHS was 0.43 cases per 100,000 population, based on the 32 patients who resided within Salvador. The overall incidence of severe leptospirosis was 4.65 cases per 100,000 population (341 cases). SPHS cases occurred during the same winter period of seasonal rainfall during which non-SPHS leptospirosis cases were identified. All SPHS case-patients were residents of slum settlements from which non-SPHS case-patients were identified before and after the appearance of SPHS. Most SPHS case-patients were adults (mean age 37.6 [+ or -] 19.4 years) and male (70%) (Table 1). However, women had higher risk (30% vs. 17%, SPHS vs. non-SPHS leptospirosis; odds ratio 2.87, 95% confidence interval 1.36-5.98) of acquiring SPHS. A case-control investigation did not identify significant risk exposures for acquiring SPHS among leptospirosis cases. Serologic testing found that the highest agglutination titers were directed against L. interrogans serovar Copenhageni in 22 (96%) of 23 and 285 (90%) of 316 SPHS and non-SPHS cases, respectively, which were confirmed by MAT (Table 1). Culture isolation procedures were not implemented from 2001 through 2005, but an isolate was obtained from an SPHS patient in 2006. Serotyping procedures (11) identified it as L. interrogans serovar Copenhageni.

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Conclusions

There has been growing recognition of the importance of leptospirosis as the cause of SPHS (1-3). Yet except for a few outbreak situations (4-6), it remains unclear whether increased reporting represents enhanced detection of an under-recognized manifestation (3) or de novo emergence of this disease form. This investigation identified the appearance of SPHS in a region in which urban leptospirosis is endemic and active surveillance was in place. Prior under-recognition of this syndrome was unlikely because clinicians were aware of SPHS's occurrence in other Brazilian cities (7,8,12). Laboratory confirmation of leptospirosis was obtained for 79% of the cases, indicating that SPHS was due to this disease rather than to other causes of hemorrhagic fever. Three years after the first case was identified, SPHS accounted for 19% of hospitalizations and 55% of the deaths from leptospirosis.

Our findings underscore the difficulties in identifying SPHS, even in the setting of heightened surveillance. The fatality rate was 74% among SPHS patients despite aggressive supportive care. Clinical parameters that could differentiate patients at risk of acquiring SPHS were not found during initial evaluation, thereby hampering attempts to implement timely triage procedures. Finally, pulmonary hemorrhage was only identified in 40% of the patients at the time of endotracheal intubation. Recognition of SPHS will therefore need to rely on a high index of suspicion in patients who have acute respiratory insufficiency.

That we did not identify environmental risk exposures for acquiring SPHS suggests a role for pathogen or host-specific factors. In Thailand, the recent sustained outbreak of leptospirosis was due to the widespread introduction of a Leptospira clone (14). Our findings suggest that the agent for SPHS in Salvador was L. interrogans serovar Copenhageni, which was also the cause of non-SPHS leptospirosis in this setting (11,15). Further isolation studies and genotyping analyses are needed to determine whether the appearance of SPHS is due to introduction or emergence of a clone that has enhanced virulence, within this serovar. Gender-specific factors, whether risk activities or host-susceptibility determinants, may have contributed to acquiring SPHS because women who with leptospirosis had twice the risk for this disease form. A large proportion of the world's slum population resides in leptospirosis-endemic regions. Research is needed to elucidate the factors responsible for transmission of SPHS so that effective prevention can be identified.

Acknowledgments

We thank the staff at Hospital Couto Maia and Secretaries of Health for the city of Salvador and the state of Bahia for their assistance in conducting the study; Rudy Hartskeerl for monoclonal antibodies used to serotype clinical isolates; and Lee Riley for his critical advice during the preparation of the manuscript.

This work was supported by the Brazilian National Research Council (grants 300861/1996, 554788/2006) and the National Institutes of Health (grants 5R01AI052473 and 5043TW00919).

References

(1.) Levett PN. Leptospirosis. Clin Microbiol Rev. 2001;14:296-326.

(2.) McBride AJ, Athanazio DA, Reis MG, Ko AI. Leptospirosis. Curr Opin Infect Dis. 2005;18:376-86.

(3.) Segura ER, Ganoza CA, Campos K, Ricaldi JN, Torres S, Silva H, et al. Clinical spectrum of pulmonary involvement in leptospirosis in a region of endemicity, with quantification of leptospiral burden. Clin Infect Dis. 2005;40:343-51.

(4.) Sehgal SC, Murhekar MV, Sugunan AR Outbreak of leptospirosis with pulmonary involvement in north Andaman. Indian J Med Res. 1995;102:9-12.

(5.) Trevejo RT, Rigau-Perez JG, Ashford DA, McClure EM, Jarquin-Gonzalez C, Amador JJ, et al. Epidemic leptospirosis associated with pulmonary hemorrhage-Nicaragua, 1995. J Infect Dis. 1998;178:1457-63.

(6.) Park SK, Lee SH, Rhee YK, Kang SK, Kim KJ, Kim MC, et al. Leptospirosis in Chonbuk Province of Korea in 1987: a study of 93 patients. Am J Trop Med Hyg. 1989;41:345-51.

(7.) Marotto PC, Nascimento CM, Eluf-Neto J, Marotto MS, Andrade L, Sztajnbok J, et al. Acute lung injury in leptospirosis: clinical and laboratory features, outcome, and factors associated with mortality. Clin Infect Dis. 1999;29:1561-3.

(8.) Nicodemo AC, Duarte MI, Alves VA, Takakura CF, Santos RT, Nicodemo EL. Lung lesions in human leptospirosis: microscopic, immunohistochemical, and ultrastructural features related to thrombocytopenia. Am J Trop Med Hyg. 1997;56:181-7.

(9.) Panaphut T, Domrongkitchaiporn S, Thinkamrop B. Prognostic factors of death in leptospirosis: a prospective cohort study in Khon Kaen, Thailand. Int J Infect Dis. 2002;6:52-9.

(10.) Yersin C, Bovet P, Merien F, Clement J, Laille M, Van Ranst M, et al. Pulmonary haemorrhage as a predominant cause of death in leptospirosis in Seychelles. Trans R Soc Trop Med Hyg. 2000;94:71-6.

(11.) Ko AI, Galvao Reis M, Ribeiro Dourado CM, Johnson WD Jr, Riley LW. Urban epidemic of severe leptospirosis in Brazil. Salvador Leptospirosis Study Group. Lancet. 1999;354:820-5.

(12.) Goncalves AJ, de Carvalho JE, Guedes e Silva JB, Rozembaum R, Vieira AR. Hemoptysis and the adult respiratory distress syndrome as the causes of death in leptospirosis. Changes in the clinical and anatomicopathological patterns [in Portuguese]. Rev Soc Bras Med Trop. 1992;25:261-70.

(13.) McBride AJ, Santos BL, Queiroz A, Santos AC, Hartskeerl RA, Reis MG, et al. Evaluation of four whole-cell Leptospira-based serological tests for the diagnosis of urban leptospirosis. Clin Vaccine Immunol. 2007;14:1245-8.

(14.) Thaipadungpanit J, Wuthiekanun V, Chierakul W, Smythe LD, Petkanchanapong W, Limpaiboon R, et al. A dominant clone of Leptospira interrogans associated with an outbreak of human leptospirosis in Thailand. PLoS Negl Trop Dis. 2007 Oct 31;1(1):e56.

(15.) Barocchi MA, Ko AI, Ramos FS, Faria MT, Reis MG, Riley LW. Identification of new repetitive element in Leptospira interrogans serovar copenhageni and its application to PCR-based differentiation of Leptospira serogroups. J Clin Microbiol. 2001;39:191-5.

Address for correspondence: Albert I. Ko, Centro de Pesquisas Goncalo Moniz, Fundacao Oswaldo Cruz, Rua Waldemar Falcao 121, 40296-710 Salvador, Bahia, Brazil; email: [e-mail]

Edilane L. Gouveia, * John Metcalfe, ([dagger]) Ana Luiza F. de Carvalho, * Talita S.F. Aires, * Jose Caetano Villasboas-Bisneto, * Adriano Queirroz, * Andreia C. Santos, * Katia Salgado, ([double dagger]) Mitermayer G. Reis, * and Albert I. Ko * ([section])

* Fundagao Oswaldo Cruz, Ministerio da Saude, Salvador, Bahia, Brazil; ([dagger]) University of California, San Francisco, California, USA; ([double dagger]) Hospital Couto Maia, Secretaria da Saude do Estado da Bahia, Salvador, Bahia, Brazil; and ([section]) Weill Medical College of Cornell University, New York, New York, USA

Dr Gouveia is an infectious disease physician and researcher at the Oswaldo Cruz Foundation, Brazilian Ministry of Health, in Salvador, Brazil. Her research interests focus on infectious disease problems that affect urban slum populations.

Table 1. Characteristics of leptospirosis patients identified during
active surveillance in metropolitan Salvador, Brazil, from 2003
through 2005, according to presence of SPHS

                                               With SPHS

                                        No.            No. (%)
Characteristics                      responses   or mean [+ or -] SD

Age, y                                  44       37.6 [+ or -] 19.4
Female sex                              47             14 (3)

Clinical manifestations
  Days of symptoms before               43        6.3 [+ or -] 3.6
    hospitalization
  Respiratory insufficiency             47             20 (42)
    ([dagger])
  Hemoptysis                            47             7 (15)
  Jaundice                              47             40 (85)
  Total serum bilirubin, mg/dL          22       17.8 [+ or -] 13.4
  Oliguria                              47             22 (47)
  Blood urea nitrogen, mg/dL            33         121 [+ or -] 78
  Serum creatinine, mg/dL               33        3.9 [+ or -] 2.3
  Hypotension ([double dagger])         42             12 928)
  Leukocyte count, [10.sup.3]           45        15.3 [+ or -] 8.0
    cells/[mm.sup.3]
  Hematocrit, %                         23        31.8 [+ or -] 7.1
  Thrombocytopenia ([section])          21             6 (29)

Therapeutic interventions
  Dialysis                              47             25 (53)
  Packed erythrocyte transfusion        47             28 (60)
  Intensive care unit admission         47             44 (94)

Hospital outcome
  Death                                 47             35 (74)
  Days of hospitalization for           35        3.2 [+ or -] 2.5
    patients who died
  Days of hospitalization for           12       20.8 [+ or -] 15.0
    survivors

Confirmed case [paragraph]              47             37 (79)
  Serovar Copenhageni as the            23             22 (96)
    presumptive infecting agent #

                                               Without SPHS

                                        No.            No. (%)
Characteristics                      responses   or mean [+ or -] SD

Age, y                                  427      34.9 [+ or -] 14.5
Female sex                              427            55 (13)

Clinical manifestations
  Days of symptoms before               419       6.1 [+ or -] 2.8
    hospitalization
  Respiratory insufficiency             427            73 (17)
    ([dagger])
  Hemoptysis                            427            27 (6)
  Jaundice                              427           363 (85)
  Total serum bilirubin, mg/dL          140      13.9 [+ or -] 10.3
  Oliguria                              427           106 (25)
  Blood urea nitrogen, mg/dL            254        128 [+ or -] 79
  Serum creatinine, mg/dL               254       3.8 [+ or -] 2.7
  Hypotension ([double dagger])         387            85 (22)
  Leukocyte count, [10.sup.3]           422       14.4 [+ or -] 6.5
    cells/[mm.sup.3]
  Hematocrit, %                         135       33.6 [+ or -] 6.1
  Thrombocytopenia ([section])          120            32 (27)

Therapeutic interventions
  Dialysis                              425            89 (21)
  Packed erythrocyte transfusion        424            42 (10)
  Intensive care unit admission         424           112 (26)

Hospital outcome
  Death                                 427            49 (12)
  Days of hospitalization for           49        4.8 [+ or -] 5.9
    patients who died
  Days of hospitalization for           378       9.1 [+ or -] 8.4
    survivors

Confirmed case [paragraph]              427           351 (82)
  Serovar Copenhageni as the            316           285 (90)
    presumptive infecting agent #

Characteristics                      p value *

Age, y                                 0.57
Female sex                             0.002

Clinical manifestations
  Days of symptoms before              0.70
    hospitalization
  Respiratory insufficiency            0.001
    ([dagger])
  Hemoptysis                           0.03
  Jaundice                             0.99
  Total serum bilirubin, mg/dL         0.22
  Oliguria                             0.001
  Blood urea nitrogen, mg/dL           0.60
  Serum creatinine, mg/dL              0.64
  Hypotension ([double dagger])        0.33
  Leukocyte count, [10.sup.3]          0.71
    cells/[mm.sup.3]
  Hematocrit, %                        0.11
  Thrombocytopenia ([section])         0.86

Therapeutic interventions
  Dialysis                             0.001
  Packed erythrocyte transfusion       0.001
  Intensive care unit admission        0.001

Hospital outcome
  Death                                0.001
  Days of hospitalization for          0.91
    patients who died
  Days of hospitalization for          0.02
    survivors

Confirmed case [paragraph]             0.56
  Serovar Copenhageni as the           0.71
    presumptive infecting agent (#)

* The [X.sup.2] and Student t tests were used to evaluate for
significant differences (p value <0.05) for proportions and continuous
data, respectively. SPHS, severe pulmonary hemorrhagic syndrome; SD,
standard deviation.

([dagger]) Respiratory rate [greater than or equal to] 30 per min or
use of supplemental oxygen therapy.

([double dagger]) Systolic arterial blood pressure <90 mm Hg or use of
vasoactive drugs.

([section]) Platelet count <50,000 cells/[mm.sup.3].

[paragraph] The microscopic agglutination test (MAT) and
immunoglobulin M ELISA were used for laboratory confirmation.

(#) Proportions are shown for patients who had an MAT-confirmed
diagnosis of leptospirosis and highest agglutination titers against
Leptospirosis interrogans serovar Copenhageni.

Table 2. Pulmonary manifestations of patients with
leptospirosis-associated severe pulmonary hemorrhagic syndrome
(n = 47)

                                           No.      No. (%) or mean
Characteristics *                       responses     [+ or -] SD

Onset of massive hemoptysis
  During hospital admission                47            7 (15)
  After hospitalization and before         47           21 (45)
    endotracheal intubation
  During or after endotracheal                          19 (40)
    intubation

Chest radiographic examination
  Bilateral alveolar infiltrates           24           21 (88)
  Bilateral interstitial infiltrates       24            3 (12)

Pa[O.sub.2]/Fi[O.sub.2], mm Hg             33       200 [+ or -] 155
Acute lung injury ([dagger])               33           25 (76)
Acute respiratory distress syndrome        33           21 (64)
  ([double dagger])

* Findings at initial evaluation. SD, standard deviation.

([dagger]) Defined as a ratio between arterial partial pressure of
[O.sub.2] and inspired 02 fraction (Pa[O.sub.2]/Fi[O.sub.2]) [less
than or equal to] 300 mm Hg and the presence of bilateral alveolar or
interstitial infiltrates on chest radiograph or bilateral crepitus on
physical examination, without clinical evidence of increased left
atrial pressure.

([double dagger]) Defined as Pa[O.sub.2]/Fi[O.sub.2] [less than or
equal to] 200 mm Hg in addition to criteria for acute lung injury.