Seroprevalence of Leptospirosis Among Town Service Workers in Kelantan, Malaysia
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SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH SEROPREVALENCE OF LEPTOSPIROSIS AMONG TOWN SERVICE WORKERS IN KELANTAN, MALAYSIA Mohamad Azfar Zainuddin1, Nabilah Ismail2, Siti Asma’ Hassan2, Mohd Nazri Shafei1, Mohamed Rusli Abdullah1, Zahiruddin Wan Mohamad1, Nor Azwany Yaacob1, A Mohd Nikman3, Aziah Daud1 and Maizurah O4 1Department of Community Medicine, 2Department of Medical Microbiology and Parasitology, 3Department of Anaesthesiology, Universiti Sains Malaysia, Kubang Kerian, Malaysia, 4Informatics for Community Health, Universiti Sains Malaysia, Pulau Pinang Abstract. Leptospirosis is presumed to be the most widespread re-emerging zoonotic disease of global distribution affecting humans in tropical, subtropical and temperate zones. Humans can be exposed to leptospirosis as a result of variety of occupations, such as town service worker, paddy planter, army and health care worker due to the presence of environmental determinants for human leptospirosis. This study determined seroprevalence of leptospirosis among 321 town service workers in Kelantan, a northeastern state of Malaysia, involving a cross sectional study in four districts, namely, Kota Bharu, Gua Musang, Kuala Krai, and Tanah Merah in Kelantan. Sociodemographic data were collected and sera samples screened for the presence of anti-leptospiral antibodies using IgM enzyme-linked immunosorbent assay (IgM ELISA) and confirmed by microscopic agglutination test (MAT) using a panel of 20 live leptospires obtained from Institute of Medical Research (IMR) Kuala Lumpur, Malaysia. Serovars used were australis, autumnalis, bataviae, canicola, celledoni, copenhageni, djasiman, grippotyposa, hardjobovis, hardjoprajitno, icterohaemorrha- giae, javanica, lai, melaka, pomona, pyrogenes, patoc, sarawak, tarassov, and tereng- ganu. A MAT titer of ≥100 was used as cut-off for positive samples. All participants were of Malay race, with mean age (± SD) of 40 (± 10) years and mean duration of employment of 12 (± 10) years. Ninety-eight samples were positive or indetermi- nate by IgM ELISA, and MAT revealed an overall seroprevalence of leptospirosis of 25.5% (95% CI : 20.6-30.5). Garbage collectors had the highest seroprevalence (35%; 95% CI : 8.1-14.9), followed by town cleaners (30%; 95% CI : 43.6-54.8), lorry drivers/ mechanics (20%; 95% CI : 17.8-27.4), and landscapers (14%; 95% CI : 13.1-21.8). The most common serovar was against a strain of Leptospira spp isolated from Sarawak (60%) and none positive for serovars bataviae, djasiman, hardjoprajitno, melaka, pyrogenes, pomona and terengganu. The present study highlights the high risk of leptospiral infection among town service workers in Kelantan, Malaysia. Keywords: high risk occupation, leptospirosis, seroprevalence, town service worker Correspondence: Aziah Binti Daud, Depart- INTRODUCTION ment of Community Medicine, School of Medi- cal Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia. Leptospirosis is considered to be the E-mail: [email protected]; aziahdaud68@gmail. most widespread re-emerging zoonotic com disease of global distribution affecting hu- Tel: +609 767 6633/6622; Fax: +609 767 6654 mans in tropical, subtropical and temper- 1222 Vol 48 No. 6 November 2017 SEROPREVALENCE OF LEPTOSPIROSIS AMONG TOWN SERVICE WORKERS ate zones. The most significant foci of the Thus, this study was conducted to disease are The Caribbean, Latin America, determine the seroprevalence of lepto- the Indian subcontinent, Southeast Asia, spirosis among town service workers in Oceania, and Eastern Europe (Pappas et al, Kelantan, Malaysia. 2008). Seychelles was found to have the highest prevalence of leptospirosis in the MATERIALS AND METHODS world with an annual rate of 432.1 per million population while USA reported Study population the lowest annual rate of 0.1 per million A cross sectional study was carried population (Pappas et al, 2008). The exact out in four districts (Kota Bharu, Gua number of human cases worldwide is not Musang, Kuala Krai, Tanah Merah) in known due to a lack of comprehensive Kelantan, a northeastern state of Malaysia, surveillance (Hartskeerl et al, 2011). involving 321 town service workers: gar- Incubation period of leptospirosis bage collector, town cleaner, landscaper infection is usually 5-14 days, with a range and lorry driver/mechanic. Garbage col- of 2-30 days (WHO, 2012). In humans, lector collects garbage from residential, it can cause a wide range of symptoms, commercial and industrial areas and ranging from mild (influenza- like illness dumps garbage from containers onto symptoms) to severe (Weils’ syndrome), lorry (truck) for disposal at landfills; town while some infected persons may have cleaner duties are sweeping, collecting no symptoms at all. If the infection is and removing of litter, detritus and leaves not treated, progression of the disease from public spaces; landscaper performs will lead to complications, such as renal a range of duties, such as transporting failure, meningitis, liver damage, respira- and planting new vegetation, mulching, tory distress and widespread hemorrhage fertilizing, watering, as well as cutting (Dircio Montes Sergio et al, 2012). and trimming grass; and lorry driver, in Humans may be exposed to leptospi- addition to routine work, sometimes as- rosis through occupational, recreational sists garbage collectors to perform their or environmental factors (Levett, 2001). duties, while lorry mechanic repairs and Occupation such as town service worker, undertakes maintenance of the lorries paddy planter, army and health care used for garbage collection. Sample size, worker impose higher risk of leptospiral calculated based on 24.7% seropositiv- infection due to presence of environmen- ity for leptospirosis among town service tal determinants for human leptospirosis workers (Sulong et al, 2012) at 95% confi- (Hadad et al, 2006; Tiwari, 2008; Sulong dence interval (CI) and a drop-out of 20%, et al, 2012). Town service workers are more was estimated to be 346. Participants were likely to be exposed to the leptospiral in- interviewed for socio-demographic, job fection as a result from their occupational category and duration of employment. activities in every step of solid waste Data were analyzed using SPSS Version management process. Based on data from 20.0 (IBM, Armonk, NY). an in-depth, long term and country-wide Prior written consent was obtained studies in Denmark, disease and injury from participants and ethical clearance risks for solid waste management workers was approved by Research and Ethic are six times greater than those of control Committee (Human), School of Medical population (Cointreau, 2006). Sciences, Health Campus, Universiti Sains Vol 48 No. 6 November 2017 1223 SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH Table 1 test (MAT) following standard protocols Sociodemographic characteristics of (WHO, 2007). MAT was performed with a town service workers, Kelantan, panel of 20 live leptospires obtained from Malaysia. Institute of Medical Research (IMR), Kuala Lumpur, Malaysia. Serovars used were Characteristic Number australis, autumnalis, bataviae, canicola, (%) celledoni, copenhageni, djasiman, grip- (N = 321) potyposa, hardjobovis, hardjoprajitno, Age (year), mean (SD) 41 (10) icterohaemorrhagiae, javanica, lai, mela- Gender ka, pomona, pyrogenes, patoc, sarawak, Male 309 (96) tarassov, and terengganu. MAT titer of Female 12 (4) ≥100 was taken as cut-off for a positive Marital status sample. Seroprevalence of leptospirosis Married 268 (83) was described with 95% CI. Single 44 (14) Widower 9 (3) Number of children, mean (SD) 4 (2) RESULTS Monthly income (RM), mean (SD) 1,198 (419) Three hundred and twenty-one town Education level service workers were enrolled in the No formal education 4 (1) Primary school 64 (20) study. All participants were of Malay race Lower secondary school 88 (28) with a mean ± SD age of 41 ± 10 years, Upper secondary school 151 (47) with mean duration of employment of 12 Form 6/Diploma 14 (4) ± 10 years. Majority of them were from Town council Kota Bharu municipal council and work Kota Bharu Municipal Council 183 (57) as town cleaner. Their education status Gua Musang District Council 48 (15) mainly at the level of upper and lower Kuala Krai District Council 49 (15) secondary school (Table 1). Tanah Merah District Council 41 (13) Ninety-eight serum samples from 321 Job category Town cleaner 157 (49) subjects (30.5%) were positive or inde- Lorry driver/mechanic 71 (22) terminate in the IgM-ELISA. Subsequent Landscaper 56 (17) MAT revealed an overall seroprevalence Garbage collector 37 (12) of leptospirosis of 25.5% (82/321) (95% CI: 20.6-30.5). Garbage collectors had the highest seroprevalence (35.1%; 95% CI: 8.1-14.9), followed by town cleaners (30%; Malaysia [Reference no: USMKK/PPP/ 95% CI: 43.6-54.8), lorry drivers/mechan- JEPeM 261.3(7)]. ics (20%; 95% CI: 17.8-27.4), and landscap- Sample analysis ers (14%; 95% CI: 13.1-21.8) (Table 2). Five ml of venous blood were ob- The most common serovar among the tained from each participant and stored 82 seropositive subjects as determined by at 4-8ºC until used. Serum samples were positive MAT with titer ≥100 was sarawak screened for the presence of anti-leptospir- (60%) (Table 3). None of the samples were al antibodies using IgM enzyme-linked positive for serovars bataviae, djasiman, immunosorbent assay (IgM ELISA) and hardjoprajitno, melaka, pyrogenes, po- confirmed by microscopic agglutination mona and terengganu. 1224 Vol 48 No. 6 November 2017 SEROPREVALENCE OF LEPTOSPIROSIS