Transactions of the Royal Society of Tropical Medicine and Hygiene (2006) 100, 693—695

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Underestimation of snakebite mortality by hospitalstatistics in the Monaragala District of Sri Lanka

S. Foxa, A.C. Rathuwithanab, A. Kasturiratneb,D.G. Lallooa, H.J. de Silvab,∗

a Liverpool School of Tropical Medicine, Liverpool, UKb Faculty of Medicine, University of Kelaniya, P.O. Box 6, Ragama, Sri Lanka

Received 29 June 2005; received in revised form 1 September 2005; accepted 5 September 2005Available online 14 November 2005

KEYWORDSSnakebite;Mortality;Sri Lanka

Summary Estimates of snakebite mortality are mostly based on hospital data, although thesemay considerably underestimate the problem. In order to determine the accuracy of hospital-based statistics, data on snakebite mortality in all hospitals in the Monaragala District of SriLanka were compared to data on snakebite as the certified cause of death for the district, forthe 5-year period between 1999 and 2003. Data were cross-checked in a sample of hospitalsand divisional secretariats within the district. Hospital statistics did not report 45 (62.5%) of thetrue number of snakebite deaths in the Monaragala District. Twenty-six (36.1%) of the victimseither did not seek, or had no access to, a hospital. Another 19 (26.4%) had arrived at hospital,but had done so too late to receive treatment. Our study confirms the limitations of officialhospital-based mortality data on snakebite.© 2005 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rightsreserved.

1. Introduction

Snakebite remains a considerable challenge in many partsof the world. Current data suggest that there are more than3 million bites per year, with 150 000 deaths, worldwide(White, 2000). However, accurate data are often difficultto find as bites affect rural populations in remote areaswith limited access to formal health care (Theakston et al.,2003). There are very few community-based surveys on mor-tality related to snakebite, and these have shown high rates

∗ Corresponding author. Tel.: +94 11 2958039;fax: +94 11 2958337.

E-mail address: hjdes@sltnet.lk (H.J. de Silva).

of mortality: a survey in Nigeria showed mortality rates of5.1 to 12.2% following snakebite in some parts of the country(Pugh and Theakston, 1980); one from south-eastern Senegalshowed an annual average mortality rate of 14 per 100 000population (Trape et al., 2001); and another from rural WestBengal in India showed an average annual mortality rate of16 per 100 000 population (Hati et al., 1992). Many estimatesof snakebite incidence and mortality are based on hospitaldata, because other recording systems are unavailable orunreliable in most developing countries. However, hospitaldata may considerably underestimate the problem.

Sri Lanka has a high incidence of snakebite. In 2002,around 37 240 patients were treated for snakebite in gov-ernment hospitals; of these, 81 died (Ministry of Health, SriLanka, 2002). Officially quoted mortality rates for snakebite

0035-9203/$ — see front matter © 2005 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.doi:10.1016/j.trstmh.2005.09.003

694 S. Fox et al.

are calculated using in-patient hospital data (deaths occur-ring after admission to hospital). This is because it isassumed that most of the seriously affected bite victimswould end up in hospital. These data are sent in quarterlyfrom all hospitals on the island to the Medical StatisticsUnit of the Ministry of Health. However, in rural areas ofthe country, where snakebite is a major public health prob-lem, many victims either seek other forms of treatment(Ayurveda) or do not have the opportunity to obtain anyform of timely treatment. The death registration system inSri Lanka, implemented by the Registrar General’s depart-ment, is a separate decentralized system and records around95% of all deaths (Department of Census and Statistics, SriLanka) — a high rate for a developing country. In addition tothe patient identification data, the date, place, and causeof death are recorded.

2. Materials and methods

In order to determine the accuracy of hospital-basedstatistics for snakebite mortality, we undertook a study inMonaragala District. This is a predominantly rural, sparselypopulated, agriculture-based district in the southeast ofSri Lanka with few modern amenities and poor access tohealth facilities. There are 18 hospitals in the district, butonly one provides specialist services. In 2002, 2152 patientswere treated for snakebite in the district’s hospitals.StdHiTtadcpd(fioueE

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3. Results

In total, 27 snakebite deaths were recorded from hospitalsin the Monaragala District in the 5-year period. However,the Registrar General’s death registrations for the sameperiod identified 72 deaths due to snakebite in the district.All hospital snakebite deaths were accurately documentedin the Registrar General’s death registration system. Inaddition to these 27 deaths, the Registrar General’s datarecorded another 19 deaths due to snakebite as havingoccurred ‘at hospital’. These were deaths that had occurredbefore the victim could be admitted to the hospital (thatis, death immediately after presentation to hospital orwhen the victims were found to be dead at presentation).The certification of these deaths had been performed bya Registrar of Births and Deaths, based on a declarationissued by the coroner at the hospital, who in turn hadbeen informed of the death by the admitting medicalofficer.

Therefore, hospital statistics did not report 45 (62.5%)of the true number of snakebite deaths in the MonaragalaDistrict; they reported only 27 (37.5%). Of the 72 deaths dueto snakebite for the district, 26 (36.1%) of the victims eitherdid not seek, or had no access to, a hospital. Another 19(26.4%) (that is, 19 of the 45 deaths not recorded in the datasent to the Medical Statistics Unit by individual hospitals)had, in fact, arrived at hospital, but had done so too late tor

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nakebite mortality data over a 5-year period from 1999o 2003 were obtained for all hospitals in the Monaragalaistrict from the Medical Statistics Unit of the Ministry ofealth. All hospital deaths recorded under the code T. 63.0

n ICD 10 (snakebite) for Monaragala district were selected.he reporting hospital and the quarter of the year in whichhe death occurred were obtained from quarterly morbiditynd mortality returns sent from individual hospitals in theistrict to this unit. Data on snakebite as the certifiedause of death for the Monaragala District during the 5-yeareriod were also obtained from the Registrar General’separtment. In addition to the patient identification dataname, age, sex, permanent address, occupation, name ofather and mother) the Registrar General’s death recordsnclude the date of death, place of death and the causef death in detail (immediate, antecedent and contrib-tory causes of death). All data were entered into dataxtraction forms and a database was created in Microsoftxcel 2002.

All hospital deaths reported to the Medical Statistics Unitere cross-checked with the Registrar General’s data with

egard to place and date of death. The numbers of deathsecorded for each hospital at the Medical Statistics Unitere then cross-checked with patient records at 10 of the8 hospitals (including the main hospital). This was doney checking individual patient records and hospital regis-ers for the 5-year period. The data obtained from individualatient records from hospitals were then cross-checked withhe death certification records obtained from the Registrareneral’s department, by comparison of patient name, agend sex. The Registrar General’s mortality data were cross-hecked with records available at 19 of the 33 divisionalecretariats within the district of Monaragala, using patientdentification data.

eceive any treatment.We found that data recorded centrally at both the Med-

cal Statistics Unit and the Registrar General’s departmentorresponded to what was documented in the sample of hos-itals and divisional secretariats that we visited; we verified8 (66.7%) of the 27 hospital recorded deaths, 14 (73.7%) ofhe deaths that had occurred ‘at hospital’ but before theatient could be admitted to hospital, and 36 (50%) of theegistrar General certified deaths in the Monaragala District.

. Discussion

lthough a few death registrations may have been misat-ributed to snakebite, our study demonstrates that hospitaltatistics underestimate three-fold the true burden ofnakebite mortality. In Africa, it is estimated that lesshan half the deaths due to snakebite are reported by theealth services, and similar under-reporting is likely toccur in most African and Asian countries where snakebites prevalent (Chippaux, 1998). In remote rural areas ofhe tropics it is estimated that a third to more thanalf of snakebite victims do not receive treatment at aospital (Chippaux, 1998). Thus, a proportion of snakebiteeaths can occur before the victims can reach a hospital,nd in some instances victims with fatal bites may notttempt to use formal health care services (Chippaux,998; Sawai et al., 1983; Theakston et al., 2003). Althoughhis has been long suspected here, we have attemptedo quantify the problem; in this study, 36.1% of snakebiteeaths occurred outside hospital, and another 26.4% of theictims who died reached hospital too late to receive anyreatment. The probable reasons include poor transportnd communication facilities, and a preference to seekraditional treatments for snakebite, which are more

Underestimation of snakebite mortality 695

easily accessible to these communities (Hati et al., 1992;Makita, 2003). Traditional healers often refer patients tohospital only after severe systemic manifestations develop,by which time the patient’s condition may have becomecritical.

Although our study was limited to the Monaragala Dis-trict, the district is fairly representative of rural Sri Lanka,and our findings are likely to reflect the situation in manyareas of the country, and indeed many parts of the worldin which snakebite is a problem and public amenities arelimited.

Conflicts of interest statementThe authors have no conflicts of interest concerning the workreported in this paper.

References

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