|
|
Dispatch
Human Rabies: A Reemerging
Disease in Costa Rica?
Xiomara Badilla,* Victor Pérez-Herra,† Ligia Quirós,‡ Ana Morice,§
Edwin Jiménez,‡ Elizabeth Sáenz,§ Fernando Salazar,¶ Rodrigo Fernández,#
Lillian Orciari,** Pamela Yager,** Sylvia Whitfield,** and Charles E.
Rupprecht**
*Caja Costarricense de Seguro Social (CCSS), San José, Costa Rica; †Hospital
Nacional de Niños, San José, Costa Rica; ‡Ministerio de Agricultura y
Ganadería, San José, Costa Rica; §Instituto Costarricense de Investigación
y Enseñanza en Nutrición y Salud (INCIENSA), San Isidro de Pérez Zeledón,Costa
Rica; ¶Epidemiología, Región Brunca, CCSS, Tres Ríos, Cartago, Costa Rica;
#Epidemiología, Región Brunca, Ministerio de Salud de Costa Rica, San
Isidro de Pérez Zeledón; **Centers for Disease Control and Prevention,
Atlanta, Georgia, USA
Suggested citation for this article: Badilla
X, Pérez-Herra V, Quirós L, Morice A, Jiménez E, Sáenz E, et al. Human
rabies: a reemerging disease in Costa Rica? Emerg Infect Dis [serial
online] 2003 Jun [date cited]. Available from: URL: http://www.cdc.gov/ncidod/EID/vol9no6/02-0632.htm
Two human rabies
cases caused by a bat-associated virus variant were identified in September
2001 in Costa Rica, after a 31-year absence of the disease in humans.
Both patients lived in a rural area where cattle had a high risk for
bat bites, but neither person had a definitive history of being bitten
by a rabid animal. Characterization of the rabies viruses from the patients
showed that the reservoir was the hematophagous Vampire Bat, Desmodus
rotundus, and that a sick cat was the vector.
Multiple studies in North and South America (1-3), Africa
(4), Australia (5), Asia (6),
and Europe (7) have documented the importance of rabies
maintenance by various bat species. Aerosol transmission from bats was
once considered as a possible mechanism in human rabies acquisition; however,
because most patients lack a documented history of an animal bite, a more
plausible explanation is that people, unaware of the risk of acquiring
rabies from bat bites, are bitten by infected bats (8-10).
The last human rabies case in Costa Rica, before the case we document,
occurred in 1970, before the control of rabies in domestic animals had
improved. The last documented case of canine rabies occurred in the North
Pacific Coast (Salinas Bay) in 1987, and 26 cases of cattle rabies caused
by Vampire Bat bites were reported during the 1990s. In September 2001,
after 31 years without any known case of human rabies in Costa Rica, the
National Children’s Hospital reported a suspected case of paralytic rabies
in a child referred from a regional hospital in the Brunca Region.
Case Report
On September 12, 2001, a 9-year-old boy from La Gamba, Río Claro, in
the Brunca Region of Costa Rica, was admitted to a local hospital with
fever, cough, and malaise of 4 days’ duration. On September 19, he returned
to the hospital because of muscular weakness; he and was referred to the
regional hospital on September 23 with acute flaccid paralysis that rapidly
progressed to respiratory failure. The patient was intubated and transferred
to the National Children´s Hospital with a diagnosis of viral encephalomyelitis.
His severe central nervous system involvement progressed to coma in <24
h with muscle hypotonia. A computed tomographic scan showed generalized
brain edema, and an electroencephalogram indicated diffuse and severe
cerebral damage. The child died 6 days after hospital admission on September
29. A nuchal skin biopsy tested negative for rabies virus antigen by an
immunofluorescence antibody assay, but postmortem brain tissue tested
positive. Rabies virus was isolated by injecting mice with brain tissue
from the child.
A field investigation was carried out to identify the likely mechanism
of transmission. The house where the child had lived during the previous
4 months was in a wooded zone (Figure 1). In an
interview, two members of the family noted that a 62-year-old woman who
was in charge of the child died in a similar manner. On September 17,
she exhibited malaise, muscular pain, headache, insomnia, and anxiety.
On September 23, she was admitted to the local hospital, but because of
the severity of her disease, she was transferred to the regional hospital
on September 26. On September 29, she had sialorrhea, hemiplegia, and
loss of muscular strength in her right arm; she also showed bizarre behavior
and respiratory failure that progressed to apnea. She died on September
30. Characterization of the agents, conducted at the Centers for Disease
Control and Prevention, demonstrated a rabies virus variant associated
with vampire bats (Desmodus rotundus) from both patients, as described
elsewhere in Latin America (11).
After the diagnosis of rabies was made, additional history was obtained
about potential animal exposures. The family reported that during the
middle of July 2001, their cat became very aggressive and demonstrated
strange behavior. Their dog attacked the cat, and while the woman and
child tried to stop the fight, the cat bit them. The dog killed the cat,
and the carcass was discarded into a creek next to the house. (The body
of the cat was not found during the investigation.) After the human cases
were reported, the dog was confined with close observation, and in December
2001, it was euthanized. Postmortem brain tissue samples from the dog
tested negative for rabies virus antigen.
Because rabies occurs in cattle in Costa Rica and because persons living
in areas where contact with Vampire Bats is likely are at risk for of
viral transmission, the Program of Animal Health of the Ministerio de
Agricultura y Ganadería had implemented a Geographic Information System
(GIS) during 1980. This animal surveillance system divided the country
into 2,234 small areas (5 x 5 km2). Trained veterinary technicians
used a national census of animals to register the number of weekly Vampire
Bat bites from the farms included in each area. According to the frequency
of Vampire Bat bites in cattle, the presence of rabies virus in populations
of bats, and ecologic variables (e.g., temperature, precipitation, altitude,
and land use), the GIS program defines areas of low, medium, and high-risk
of disease (Figure 2). During August and September
2001, the GIS of animal health surveillance reported 169 cattle bites
by Vampire Bats in the Brunca Region (rate 3.5%). Where the two patients
lived, the rate of such attacks was 10.4%, and the area was classified
as a high-risk zone for bat bites to cattle (Figure
3).
Rabies postexposure prophylaxis with a Vero cell rabies vaccine was administered
to the relatives of the patients and to veterinary and healthcare personnel,
who were in contact with the saliva of the patients. A retrospective search
of other possible human cases was performed by analyzing the deaths with
unknown origin in the discharge registry of the hospitals of the Brunca
Region and the registry of the National Morgue. The case definition used
was the following: any acute encephalopathy of unknown origin, with atypical
focal neurologic signs or encephalomyelitis in any person who died between
January 1 and September 30, 2001, in the Brunca Region. The search did
not find any additional suspicious deaths associated with rabies in the
region.
Conclusions
After 31 years without a case of human rabies in Costa Rica, the disease
reemerged. Its reappearance reinforces the importance of an integrated
network between veterinary and human health programs to identify risk
zones of bat bites and to prevent human and animal cases. The active participation
of combined health services in the early warning of the occurrence of
suspected cases of emergent diseases is essential for effective, integrated
surveillance. Human rabies must always be considered in the differential
diagnosis of acute flaccid paralysis with consciousness impairment, even
in patients without a known history of animal bite (giving priority to
those in zones where cattle are at high risk for bat bites).
Rabies in bats was first reported during the 1920s. Since then, rabies
has been confirmed in several species of bats. The historical association
between Vampire Bats and livestock may tend to subvert the epidemiologic
surveillance in other species, such as domestic animals such as cats and
dogs (12). This lack of association with other species
could be due to a lack of intensified surveillance or to unknown factors
related to the virus, host, or ecology.
Several studies have documented the transmission of rabies virus in the
absence of a history of documented animal bite (13,14).
No typical bite marks were observed in either of the patients, but the
history of cat bite raises the possibility of an indirect manner of transmission,
through the bite of another vector, previously infected by a bat. At the
community level, the immigration of human populations throughout rural
areas increases the risk of contact with hematophagous bats and facilitates
the transmission of the virus to humans.
The presence of rabies in humans in Costa Rica associated with bat bites
has demonstrated the importance of strengthening the integrated surveillance
of animal and human health care. The GIS operation permits the identification
of risk zones, so that measures for optimal control and prevention can
be established. Participation of communities located in high-risk areas
is a key strategy for the prevention and early detection of possible cases
of rabies. Emergence of human rabies from infected wildlife, especially
in countries where the disease has been eliminated in dogs, reinforces
the need for maintaining awareness of both physicians and public health
workers alike, as well as for improving laboratory tools needed for rapid
rabies diagnosis.
Acknowledgments
We appreciate the participation of personnel in this
investigation from the Brunca Health Region, the National Children's
Hospital, the National Center of Reference of Instituto Costarricense
de Investigación y Enseñanza en Nutrición y Salud,
and the Laboratory of Animal Health of the Ministerio de Agricultura
y Ganadería, as well as staff in the Viral and Rickettsial Zoonoses
Branch, Centers for Disease Control and Prevention, for their collaboration.
Dr. Badilla is chief of the Epidemiological Surveillance
Program in the Social Security System of Costa Rica. Her work focuses
on vector-borne infectious diseases.
References
- Centers for Disease Control and Prevention. Human
rabies-Tennessee, 2002. MMWR Morb Mortal Wkly Rep MMWR 2002;51:828-9.
- Human rabies—Quebec, Canadá, 2000. MMWR Morb Mortal Wkly Rep MMWR
2000;49:1115–6.
- Favi M, de Mattos CA, Yung V, Chala E, Lopez LR, de Mattos CC.
First case of human rabies in Chile caused by an insectivorous bat virus
variant. Emerg Infect Dis 2002;8:79–81.
- King AA, Meredith CD, Thomson GR. The
biology of southern African lyssavirus variants. Curr Top Microbiol
Immunol 1994;187:267–95.
- Hanna JN, Carney IK, Smith GA, Tannenberg AE, Deverill JE, Botha JA,
et al. Australian
bat lyssavirus infection: a second human case, with a long incubation
period. Med J Aust 2000;172:597–9.
- Arguin P, Murray K, Miranda M, Smith J, Calaor A, Rupprecht C. Serologic
evidence of Lyssavirus infections among bats, the Philippines.
Emerg Infect Dis 2002;8:258–62.
- Serra-Cobo J, Amengual B, Abellán C, Bourhy H. European
bat Lyssavirus infection in Spanish bat population. Emerg
Infect Dis 2002;8:413–20.
- Pape WJ, Fitzsimmons T, Hoffman R. Risk
for rabies transmission from encounters with bats, Colorado, 1977-1996.
Emerg Infect Dis 1999;5:433–7.
- Plotkin SA.
Rabies. Clin Infect Dis 2000;30:4–12.
- Gibbons RV, Holman RC, Mosberg SR, Rupprecht CE. Knowledge
of bat rabies and human exposure among United States cavers. Emerg
Infect Dis. 2002;8:532–4.
- Warner C, Zaki S, Shieh WJ, Whitfield S, Smith, J,
Orciani L, et al. Laboratory
investigation of human deaths from vampire bat rabies in Perú. Am
J Trop Med Hyg 1999;60:502–7.
- Pawan JL. The transmission of rabies in Trinidad by the vampire bat.
Ann Trop Med Parasitol 1936;30:101–30.
- Vigilancia Epidemiológica de la rabia en las Américas 1996. Boletín
de Vigilancia Epidemiológica de las Américas, Volumen 28. Buenos Aires:
Instituto Panamericano de Protección de Alimentos y Zoonosis/Organización
Panamericana de la Salud; 1996.
- Messenger SL, Smith JS, Rupprecht CE. Emerging
epidemiology of bat-associated cryptic cases of rabies in humans in
the United States. Clin Infect Dis 2002;35:738–47.
|
