Epidemiology of tetanus in Jamaica,1993–2010

Background

Over the past few decades, better immunisation practices and prophylaxis have reduced the prevalence of tetanus in developed nations,^1,2 although it remains endemic in many developing countries. As testimony to this, the World Health Organization received reports of 10,011 cases of tetanus across the globe in 2012. ³

Although tetanus remains endemic in Jamaica, ⁴ the epidemiologic profile has not been reported. This study aims to document the epidemiology of tetanus in order to direct public health efforts to eradicate tetanus in Jamaica.

Methods

This study was done at the University Hospital in Kingston – a 500-bed facility that serves as the main tertiary referral centre for the country. ⁵ Approval from the institutional review board was secured to allow access to hospital records for this study.

Admission registers were accessed to identify all patients with a diagnosis of tetanus between 1 January 1993 and 1 December 2010. We also reviewed the national surveillance database maintained by the Ministry of Health in order to identify patients who may have been treated for tetanus at smaller institutions without transfer to the national referral hospital. All hospital records were retrospectively reviewed and the following data were extracted: patient demographics, injury details, disease severity, duration of hospitalisation and mortality. Disease severity was graded according to the Ablett Classification. ¹ Patients with Grades 3 and 4 tetanus were considered to have severe disease. The data were analysed using SPSS version 12.0.

Results

There were 26 patients diagnosed with tetanus in the 17-year period (mean 1.53 cases per year). At the last census in 2011, there were 2,697,983 people residing in Jamaica. ⁶ Therefore, the annual incidence of tetanus over the study period was 0.57 cases per 1,000,000 population.

There was a preponderance of men (5.2:1) at a mean age of 59 years (SD ± 18.1; range, 22–88 years). When analysed by age, four (15%) patients were aged <40 years, 11 (42%) were aged 40–60 years and 11 (42%) were aged >60 years. There were no neonatal cases and the youngest patient was aged 22 years.

Complete demographic information was unavailable in the earlier part of the study because paper-based files were discarded or destroyed. However, in 21 patients for whom information was available, 11 (52%) were in high-risk occupations (farmers, gardeners and construction workers), five (24%) were in low-risk service jobs (drivers, office jobs, teachers, etc) and five (24%) were retired or unemployed. Geographically, 12 (46%) patients resided near Kingston and 10 (39%) lived in rural areas across Jamaica (Figure 1). There were no cases from Western Jamaica. OPEN IN VIEWER

Overall, 77% of patients had severe tetanus, requiring mean ICU stay of 31.9 ± 29 days (range, 3–109 days; median, 30.5 days) and resulting in four (15%) deaths despite medical therapy.

Discussion

Tetanus remains endemic in Jamaica, with an annual incidence of 0.57 cases per million population. As expected, this is greater than the annual incidence reported in developed nations that ranges from 0.1 per million in the United States ⁷ to 0.2 per million in England and Wales. ³ However, the incidence in Jamaica was lower than that in other developing countries, such as Ghana with an annual incidence of 1.06 per million. ⁸

Although entirely preventable by immunisation and wound debridement, tetanus places a heavy toll on healthcare resources in Jamaica, with 32 days mean ICU stay and 15% mortality. It is clear that there is a need to revisit the existing preventative strategies.

The majority (52%) of cases occurred in people with high-risk occupations such as farmers, gardeners, manual labourers and construction workers. Incidentally, these people are in the lower income bracket and may not have ready access to healthcare, possibly explaining the high prevalence of severe disease. It may also explain the male preponderance in Jamaica, while most existing reports in the medical literature document a greater risk for tetanus in women.^1–3

It was not surprising that 46% of the cases occurred around Kingston where 31% of the population (826,880 people) reside. ⁶ An additional 39% of patients contracted tetanus in rural, agriculture-based regions in central Jamaica. Therefore, educational programmes should target persons in high-risk occupations, such as farmers in central Jamaica and contruction workers in industrial regions. Public health educational campaigns have been shown to reduce the risk of injuries in other high-risk groups, such as people with diabetes mellitus, and it also positively influences their wound care knowledge. ⁹

In this series, there were no cases of neonatal tetanus and the mean age to contract tetanus was 59 years. It is likely that the infant immunisation programmes have shifted the susceptible population toward the older age groups. In Jamaica, there is a policy for routine supplemental immunisation of pregnant women enrolled in antenatal clinics. ¹⁰ This affords protection for women and allows neonatal immunity through transplacental transfer of immunoglobulins. This likely contributed to the low incidence of tetanus in women and neonates in Jamaica. This is a worthwhile practice to continue and its importance should be emphasised to pregnant women and all healthcare workers delivering maternity services. Immunisation requirements for school entry may also have influenced the low incidence of tetanus in neonates and children. This deserves commendation and should be continued.

Conclusions

Tetanus remains endemic in Jamaica, with an annual incidence of 0.57 cases per million population. There is room for improvement in prevention, with targeted strategies for the high-risk groups.