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Letter
Hantaviruses in São Paulo
State, Brazil
Luiz T.M. Figueiredo,* Marcos L. Moreli,* Gelse M. Campos,* and Ricardo
L.M. Sousa*
*University of São Paulo, São Paulo, Brazil
Suggested citation for this article: Figueiredo LTM,
Moreli ML, Campos GM, Sousa RLM. Hantaviruses in São Paulo state,
Brazil. Emerg Infect Dis [serial online] 2003 Jul [date cited]. Available
from: URL: http://www.cdc.gov/ncidod/EID/vol9no7/03-0087.htm
To the Editor: Hantavirus pulmonary syndrome (HPS) is an emerging
health problem in Brazil. This syndrome was first reported in 1993 in
three persons living in a rural area of Juquitiba County; two of them
died of acute respiratory failure (1). Although Juquitiba
County is part of the metropolitan area of greater São Paulo City, patients
lived in a recently deforested region. From 1993 through 2002, approximately
200 HPS cases were reported in Brazil, with a 40% case-fatality ratio
(Ministry of Health of Brazil, Report on Hantavirus cases 1993–2002, unpub.
data).
The wild rodent Bolomys laziurus is believed to be the most important
hantavirus reservoir in the State of São Paulo, based on high levels of
specific antibodies observed in serum from captured specimens (L.E. Pereira,
Adolpho Lutz Institute, pers. comm., 2001). The economy of the inland
region of Ribeirão Preto in the State of São Paulo, with its 3.5 million
inhabitants, is based on the sugar cane agroindustry. The region has been
almost completely deforested, with important consequences to the environment
and wild rodent ecology. Twenty HPS cases were reported in Ribeirão Preto
in the last 5 years, with a 60% case-fatality ratio. Review of medical
records showed that a prodromic fever occurred in all 14 case-patients
studied; dyspnea, cough, hypotension, and tachycardia occurred in about
two thirds of patients; and hemorrhagic phenomena (hematuria, melena,
and hypermenorrhea) in about one third. Thrombocytopenia was observed
in all the patients, elevated hematocrit in about three fourths, and leukocytosis
with neutrophilia and a left shift in the differential count in about
two thirds. Serum creatinine levels were also increased (average level
2 mg/dL). Chest radiographs showed diffuse alveolar flocculant infiltrates
in most cases (2,3). Laboratory diagnosis of HPS was
made by serologic testing (enzyme-linked immunosorbent assay [ELISA])
in 18 cases and by reverse transcription–polymerase chain reaction (RT-PCR)
in 11 cases; for 7 cases, both techniques were used. We performed a nucleotide
sequence analysis of the N gene of hantavirus (residues 236–477) obtained
from the blood of 11 of the 20 patients. This analysis showed that the
infections were caused by Araraquara virus, a previously known hantavirus
that had been detected by RT-PCR in the serum of an HPS patient living
in a nearby county (4). Thus, Araraquara virus is the
causative agent of a severe form of HPS, with a high death rate. This
high death rate could also be related to the lack of adequate initial
therapy provided by clinicians who probably did not immediately suspect
HPS and may have not recommended hospitalization in intensive-care units.
In addition, some hospitalized patients were in shock when first seen
and were rehydrated with massive quantities of fluids, which may have
aggravated pulmonary edema and contributed to death.
The occurrence of 10% of the Brazilian HPS reported cases in Ribeirão
Preto indicates that this region is suitable for studying the epidemiology
of hantavirus infections. A serologic survey conducted in the region in
1999, which included 567 primary-care patients from Ribeirão Preto, Guariba,
and Jardinópolis Counties, found that 7 (1.23%) of them had immunoglobulin
(Ig) G antibodies to Sin Nombre virus by ELISA and that 5 of those lived
in Jardinópolis (population 30,000), a county where a fatal case of HPS
occurred in 1999 (5). Thus, Jardinópolis County was chosen
for a population-based survey. In May 2001, we obtained personal information
and collected fingerprick blood samples from 818 participants, 15–70 years
of age, living in urban and rural areas of the county. IgG antibodies
to the N recombinant protein of Andes virus were detected by ELISA in
the blood samples of 14.3% of the participants (5). Even
though all HPS cases in Ribeirão Preto were associated with rural activity
and rodent exposure, these serologic data suggest that hantavirus infections
are common in Jardinópolis County, independent of sex, profession, or
history of contact with rodents. None of the 14.3% participants with IgG
antibodies to hantavirus had a history of HPS-like disease, and the ELISA
test showed cross-reactions with most of the South American hantaviruses,
including Araraquara. Persons living in the urban area had higher levels
of antibodies to hantavirus than those from rural areas. In Ribeirão Preto,
the physical boundaries of cities have expanded to incorporate other areas,
encroaching upon rural areas with many popular subsidized housing complexes.
Work-related and recreational rural activities in that region are also
frequent, which makes it difficult to interpret these data. These results
suggest that in this region of southeast Brazil, hantaviruses may be causing
undiagnosed asymptomatic or clinically minor infections in addition to
typical HPS. This finding envokes important questions. Is more than one
hantavirus circulating in this region, causing mostly benign infections?
Is Araraquara virus widespread, causing mostly inapparent infections and
only rarely causing HPS? Would HPS be associated with some predisposing
condition in the infected person? If more than one hantavirus is circulating
in the region, could urban rodents be reservoirs?
Further studies are necessary to better understand the epidemiology and
clinical signs and symptoms of hantavirus infection in the region of Ribeirão
Preto. Such studies should emphasize determining the reservoirs, the modes
of virus transmission to people, and the possible distinct clinical forms
of hantavirus infections.
Acknowledgments
We thank the employees of the Health Bureau of the County
of Jardinópolis for the dedicated collaboration on the serologic survey
and Paula Padula for supplying antigen for enzyme-linked immunoabsorbent
assays.
This work was supported by the State of São Paulo Research
Foundation (FAPESP).
References
- Iversson LB. Hantavirus
pulmonary syndrome in the rural area of Juquitiba, São Paulo Metropolitan
Area, Brazil. Rev Inst Med Trop Sao Paulo 1997;39:237–8.
- Figueiredo LTM, Moreli ML, Kashima S, Almeida VSO, Félix PR, Bruno
JC, et al. Hantavirus
pulmonary syndrome (HPS) in Guariba, SP, Brazil. Report of 2 cases.
Rev Inst Med Trop Sao Paulo 1999;41:131–7.
- Figueiredo LTM, Campos GM, Rodrigues FB. Síndrome pulmonar e cardiovascular
por hantavirus: aspectos epidemiológicos, clínicos, do diagnóstico laboratorial
e do tratamento. [in Portuguese]. Rev Soc Bras Med Trop 2001;34:15–27.
- Johnson AM, de Souza LT, Ferreira IB, Pereira LE, Ksiazek TG, Rollin
PE, et al. Genetic
investigation of novel hantaviruses causing fatal HPS in Brazil.
J Med Virol 1999;59:527–35.
- Holmes RR, Boccanera R, Figueiredo LTM, Mançano SR, Pane C. Seroprevalence
of human hantavirus infection in Ribeirão Preto Region of São Paulo
State, Brazil. Emerg Infect Dis 2000;6:560–1.
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