Investigación original / Original research
Mortality due to Hymenoptera stings in
Costa Rica, 1985–2006
Mónica Prado,1 Damaris Quirós,2 and Bruno Lomonte1
Suggested citation Prado M, Quirós D, Lomonte B. Mortality due to Hymenoptera stings in Costa Rica, 1985–2006. Rev
Panam Salud Publica. 2009;25(5):389–93.
ABSTRACT Objective. To analyze mortality due to Hymenoptera stings in Costa Rica during
1985–2006.
Methods. Records of deaths due to Hymenoptera stings in 1985–2006 were retrieved from
Instituto Nacional de Estadística y Censos (National Statistics and Census Institute). Mor-
tality rates were calculated on the basis of national population reports, as of 1 July of each 
year. Information for each case included age, gender, and the province in which the death oc-
curred. In addition, reports of Hymenoptera sting accidents received by the Centro Nacional
de Intoxicaciones (National Poison Center, CNI) in 1995–2006 were obtained to assess expo-
sure to these insects.
Results. Over the 22-year period analyzed, 52 fatalities due to Hymenoptera stings were
recorded. Annual mortality rates varied from 0–1.73 per 1 million inhabitants, with a mean of
0.74 (95% confidence interval: 0.46–0.93). The majority of deaths occurred in males (88.5%),
representing a male to female ratio of 7.7:1. A predominance of fatalities was observed in the
elderly (50 years of age and older), as well as in children less than 10 years of age. The province
with the highest mortality rate was Guanacaste. The CNI documented 1 591 reports of Hy-
menoptera stings (mostly by bees) in 1995–2006, resulting in an annual average of 133 cases,
with only a slight predominance of males over females (1.4:1).
Conclusions. Stings by Hymenoptera, mostly by bees, constitute a frequent occurrence in
Costa Rica that can be life-threatening in a small proportion of cases, most often in males and
the elderly. The annual number of fatalities fluctuated from 0–6, averaging 2.4 deaths per
year. Awareness should be raised not only among the general population, but also among
health care personnel that should consider this risk in the clinical management of patients
stung by Hymenoptera.
Key words Hymenoptera, insect bites and stings/mortality, Costa Rica.
Insects of the order Hymenoptera quently involved in accidental stings to laxis (type I hypersensitivity) from a sin-
(ants, bees, wasps, hornets) are fre- humans and animals worldwide. In gle sting. In the second situation, a mas-
terms of public health, in Latin America sive bee attack can result in toxic reac-
bees constitute a relevant group of sting- tion—regardless of a pre-existing allergic
1 ing insects, both in terms of frequency condition—caused by the large amountInstituto Clodomiro Picado, Facultad de Microbio-
logía, Universidad de Costa Rica, San José, Costa and clinical severity of cases (1, 2). Acci- of venom proteins entering the body via
Rica. Send correspondence to: Bruno Lomonte, dental exposure to bee venom may be hundreds or even thousands of stings.
Instituto Clodomiro Picado, Facultad de Microbio- life-threatening due to two different Massive bee attacks have become a
logía, Universidad de Costa Rica, San José 2060,
Costa Rica; telephone: +506-2229-0344; fax: +506- mechanisms: allergic reactions and toxic public health concern in the Americas,
2292-0485; email: bruno.lomonte@ucr.ac.cr reactions. In the first situation, individu- where severe envenomations in humans
2 Centro Nacional de Intoxicaciones, Hospital Na-
cional de Niños, Caja Costarricense de Seguro So- als that are highly allergic to the venom and animals have been documented
cial, San José, Costa Rica. may develop severe systemic anaphy- (3–9). The increase in the number of such
Rev Panam Salud Publica/Pan Am J Public Health 25(5), 2009 389
Original research Prado et al. • Mortality from Hymenoptera stings in Costa Rica
attacks is explained by the spread of the FIGURES 1A–C. Mortality due to Hymenoptera stings in Costa Rica, 1985–2006. (1A) number of
“Africanized” bee, a hybrid that resulted deaths by gender; (1B) annual mortality rates, per 1 million inhabitants; and (1C) age group dis-
from the interbreeding of the European tribution of fatal cases, by gender
(Apis mellifera mellifera) and African (A.
6
m. scutellata) subspecies of honey bees (4). Male A
In 1956, the latter were introduced to Female
Brazil in an attempt to increase the com-
mercial production of honey and wax. A 4
year after their arrival, several queens es-
caped and interbred with the local bee
population. Subsequently, the expansion 2
and gradual migration of the hybrids
took place, and at present their distribu-
tion spans from South America to the 0
southern parts of the United States 
of America (1, 10). These hybrid bees,
popularly known as “killer bees,” have Year
particular features associated with a
2.0
higher frequency of attacks. They exhibit B
a strong colony defense behavior charac- 1.6
terized by pheromone-coordinated mass
attack, high reproductive rates, and lack 1.2
of discrimination in nesting sites (4).
In Costa Rica, the presence of African- 0.8
ized bees was first reported in early
1983, in San Isidro de El General (11, 12). 0.4
In recent years, deaths due to massive
bee attacks have been publicized in lo- 0.0
cal newspapers and other nonscientific
communication media, suggesting that
the number of people affected might be Year
increasing. However, we have not found 14
any reports in the literature analyzing Male C
the incidence and outcome of such acci- 12 Female
dents. Official records of deaths due to 10
stinging by bees, wasps, or hornets are
categorized together in epidemiological 8
classifications. Therefore, the aim of the 6
present study was to estimate and to an-
4
alyze the mortality due to contact with
Hymenoptera, as recorded in Costa Rica  2
in 1985–2006, taking into consideration 0
that the vast majority of cases correspond 0–9 10–19 20–29 30–39 40–49 50–59 60–69 70–79 80–89
to contact with bees. Age group (years)
METHODS
Social (Social Security Administration of Edition (ICD-9), as the E-code 905.3. Af-
Data utilized to estimate the mortality Costa Rica), the vast majority of reports terwards, in 1997–2006, when the Tenth
related to Hymenoptera stings in Costa of Hymenoptera stings in this country Edition (ICD-10) was used, the code
Rica were obtained from the records of involve bees (D. Quirós, unpublished changed to X23. The information re-
the Instituto Nacional de Estadística y data). Thus, although the data collected trieved included age, gender, and prov-
Censos (National Statistics and Census for this study is strictly referred to as Hy- ince in which the case occurred. Annual
Institute, INEC), which tracks all deaths menoptera stings, it is known to corre- mortality rates were calculated on the
and their causes  nationwide. Human ac- spond mainly to bee stings. basis of national population reports, as
cidents involving bees, wasps, and hor- Data obtained from INEC were uti- of 1 July of each year, and were also ob-
nets are classified into a single category. lized to retrospectively analyze mortal- tained from INEC.
However, it is important to note that ity due to Hymenoptera during a 22-year In addition to the mortality figures,
according to the Centro Nacional de period (1985–2006). In 1985–1996, fatali- data recorded by the CNI were utilized
Intoxicaciones (National Poison Center, ties were coded according to the Inter- to retrospectively assess the number of
CNI) of the Caja Costarricense de Seguro national Classification of Diseases, Ninth human accidents involving contact with
390 Rev Panam Salud Publica/Pan Am J Public Health 25(5), 2009
Number of dealths Mortality rate Number of deaths
19 18 95 85
19 18 96 86
19 18 97 87
19 18 98 88
19 18 99 89
19 19 90 90
19 19 91 91
19 19 92 92
19 19 93 93
19 19 94 94
19 19 95 95
19 19 96 96
19 19 97 97
19 19 98 98
19 19 99 99
20 20 00 00
20 20 01 01
20 20 02 02
20 20 03 03
20 20 04 04
20 20 05 05
20 20 06 06
Prado et al. • Mortality from Hymenoptera stings in Costa Rica Original research
Hymenoptera, regardless of the outcome. 52 deaths attributed to Hymenoptera Mortality rate due to wasps and bees in
The CNI provides information and ad- stings were reported in 1985–2006. Thus, Sweden was estimated at 0.24 per 1 mil-
vice by telephone regarding the manage- an average of 2.4 fatalities occurred an- lion inhabitants (15). In the state of São
ment of diverse types of poisonings, nually, reaching a high of 6 deaths in Paulo, Brazil, there were seven deaths
including both chemical intoxications 1995 (Figure 1A). The annual mortality due to bee stings in 1993–1998; consider-
and envenomations by animal bites and rates showed an irregular pattern, vary- ing a total of 2 462 accidents recorded, the
stings. Thus, the information retrieved ing from 0–1.73 per 1 million inhabitants lethality was 0.3% (6). In these retrospec-
from CNI was routinely acquired by a (Figure 1B), with a mean of 0.74 (95% tive analyses, as well as in the present
process involving telephone calls and confidence interval (95%CI): 0.46–0.93). work, it was not possible to distinguish
the completion of a form for every call A predominance of Hymenoptera sting- between deaths attributed to allergic reac-
reporting a case. It should be stressed related fatal cases was observed among tions and those that were envenomings.
that this information reflects only the the elderly, and occasionally, in children Studies would be needed to compara-
minimum number of cases since it is not less than 10 years of age (Figure 1C). tively estimate the relative contribution of
mandatory to report sting accidents to Regarding geographic distribution, the each to the overall Hymenoptera sting-
the CNI. Notwithstanding, these figures highest mortality rate was recorded in related mortality. 
were considered worthy of attention the province of Guanacaste—a rate six Compared to the first decade of the
given the lack of any other sources track- times that of Heredia, which had the study period analyzed, the second (1997–
ing this problem in the country. This ap- lowest (Figure 2). 2006) saw a reduction in the number of
proach has been utilized in other studies sting-related fatal cases and decline of
to analyze poisonings; for example, in ANALYSIS AND DISCUSSION mortality rates. Interestingly, this reduc-
India (13). In the present study, data on tion occurred in spite of a rise in the
Hymenoptera contact, including age, Epidemiological data on mortality number of sting-accident reports during
gender, and province in which the case caused by Hymenoptera stings are scarce the period (Figures 3A and 3B). This
occurred, over a period of 12 years (1995– in the literature. In 1991–2001, there were finding could be related to increased
2006) were compiled and analyzed. 533 deaths attributed to hornets, wasps, public awareness of the Africanized bee
and bees in the United States (14), rep- threat and to programs implemented by
RESULTS resenting an annual mortality rate of the Ministry of Health that created nu-
0.179 per 1 million inhabitants, nearly merous satellite centers for basic health
Examination of the data retrieved four times lower than the average rate care (called EBAIS) in both urban and
from INEC revealed that in Costa Rica, observed in Costa Rica (present study). rural areas. 
Of note is that most of the Hyme-
noptera sting-related deaths occurred in
FIGURE 2. Mortality due to Hymenoptera stings in the seven provincesa of Costa Rica, 1985–2006 males (88.5% of the fatal cases), despite
only a slight gender difference in sting
N cases reported to CNI (Figure 3A). The
overall male to female ratio for fatal
W E
cases was 7.7:1, in contrast to 1.4:1 for
S sting accident reports. In males, the in-
AL creased prevalence of chronic diseases,
HE such as coronary atherosclerosis, has
GU been suggested as a factor that may
contribute to their higher mortality in
bee sting accidents (16, 17). In addition,
males have been reported to be more
PU prone to developing severe reactions
SJ CA LI
after bee stings (18).
Comparison of the age distributions in
number of deaths and of reported ac-
Province Deaths Mortality rate cidents clearly evidenced the higher risk
GU 9 1.61 in the elderly. The age group 50 years
AL 13 0.86
SJ 15 0.84 and older accounted for 73% of the fa-
LI 4 0.69 PU talities. Similar observations were re-
PU 6 0.65 ported in Australia, where deaths oc-
CA 3 0.57 curred predominantly in men over 40
HE 2 0.28 years of age (16); and in Sweden (15) and
the United States (14), where most deaths
occurred in those more than 50 years 
of age.
A reliable estimation of the incidence
a GU = Guanacaste; AL = Alajuela; SJ = San José; LI = Limón; PU = Puntarenas; CA = Cartago; HE = Heredia. of Hymenoptera sting accidents in Costa
Rev Panam Salud Publica/Pan Am J Public Health 25(5), 2009 391
Original research Prado et al. • Mortality from Hymenoptera stings in Costa Rica
FIGURES 3A–C. Cases of Hymenoptera stings reported to the Centro Nacional de Intoxicaciones cases reported to CNI. A total of 1 591
of Costa Rica, 1995–2006. (3A) number of cases reported by gender and their gender distribution; persons stung by these insects were re-
(3B) annual case report rates, adjusted per 100 000 population; (3C) age-group distribution of re- corded in 1995–2006, representing an
ported cases average of 133 cases per year. Accidents
250 were slightly more common in men than
Male A in women (1.4:1 ratio), in agreement
Female
200 with findings of other studies (19, 20).
Undetermined information Also, sting reports in children and young
150 adults were more frequent than in groups
of older ages (Figure 3C). This may re-
100 flect the fact that younger people, espe-
cially children, are more frequently in-
50 volved in outdoor activities. Because of
their inherent curiosity and behavior,
0 children may have a higher risk of stings
85 96 97 98 99 00 01 02 03 04 5 69 9 9 9 9 0 0 0 0 0 00 00 by Hymenoptera, as observed in the pres-1 1 1 1 1 2 2 2 2 2 2 2
Year ent work.
6.0 B CONCLUSIONS
5.0 The analyses show that in this recent
4.0 22-year period, mortality due to Hyme-
noptera stings in Costa Rica averaged 
3.0 2.4 fatal annual cases (ranging from 0–6
deaths), with an overall mortality rate of
2.0
0.74 per 1 million inhabitants (95% CI:
1.0 0.46–0.93). Fatal cases for this type of
accident are predominantly observed in
0.0 males, especially in the elderly, but may
95 96 97 98 99 00 01 02 03 04 05 6
19 19 19 19 19 20 20 20 20 20 20 20
0 also occur in children and occasionally in
Year young adults.
This information could be of relevance
600 C to promoting awareness among the gen-
500 eral population and among specialized
health personnel, as well as for consid-
400 eration of risks during the clinical man-
300 agement of patients affected by Hyme-
noptera stings.
200
100
Acknowledgements. We are grateful
0 to the staff of INEC and CNI-CCSS for
0–9 10–19 20–29 30–39 40–49 50–59 60–69 70–79 80–89 providing the basic information for this
Age group (years) study, as well as to M. Sasa, A. Ruca-
vado, and J. M. Gutiérrez for critical
reading of the manuscript. This work
Rica could not be made, given the lack of the magnitude of the problem. For the was performed as partial requirement
any comprehensive sources of informa- year 2006, contacts with Hymenoptera for the M.Sc. degree of M. Prado at the
tion; CNI records only partially capture represented 1.5% of the total poisoning University of Costa Rica.
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RESUMEN Objetivo. Analizar la mortalidad por picaduras de himenópteros en Costa Rica en
el período de 1985 a 2006.
Métodos. Se obtuvieron los registros de picaduras de himenópteros entre 1985 y
Mortalidad por picaduras de 2006 del Instituto Nacional de Estadísticas y Censos. Las tasas de mortalidad se cal-
himenópteros en Costa Rica, cularon a partir de los datos de la población nacional para el 1 de julio de cada año.
1985–2006 La información de cada caso abarcaba la edad, el sexo y la provincia en la que ocurrió
la muerte. Además, para evaluar la exposición a estos insectos se contó con las notifi-
caciones de accidentes por picaduras de himenópteros del Centro Nacional de Intoxi-
caciones (CNI) de 1995 a 2006.
Resultados. En el período de 22 años analizado se registraron 52 muertes por pica-
duras de himenópteros. La tasa anual de mortalidad varió entre 0 y 1,73 por millón
de habitantes, con una media de 0,74 (intervalo de confianza de 95%: 0,46 a 0,93). La
mayoría de las muertes correspondieron a hombres (88,5%), con una razón hom-
bre:mujer de 7,7:1. Predominaron los casos letales en adultos mayores (50 años o más)
y niños menores de 10 años. La provincia con la mayor mortalidad fue Guanacaste. El
CNI documentó 1 591 casos de picaduras de himenópteros (principalmente abejas)
entre 1995 y 2006, para un promedio anual de 133 casos, con un ligero predominio de
hombres sobre mujeres (1,4:1).
Conclusiones. Las picaduras de himenópteros, principalmente de abejas, son suce-
sos frecuentes en Costa Rica que pueden amenazar la vida en una reducida propor-
ción de casos, principalmente hombres y adultos mayores. El número anual de muer-
tes varió entre 0 y 6, con un promedio de 2,4 muertes anuales. Se debe fomentar la
conciencia no solo en la población general sino también en el personal especializado
de salud, quienes deben tomar en cuenta este riesgo al atender a los pacientes con pi-
caduras de himenópteros.
Palabras clave Himenópteros, mordeduras y picaduras de insectos/mortalidad, Costa Rica.
Rev Panam Salud Publica/Pan Am J Public Health 25(5), 2009 393