The authors have declared that no competing interests exist.
A cross-sectional study of intestinal parasitic infections amongst migrant workers in Malaysia was conducted. A total of 388 workers were recruited from five sectors including manufacturing, construction, plantation, domestic and food services. The majority were recruited from Indonesia (n = 167, 43.3%), followed by Nepal (n = 81, 20.9%), Bangladesh (n = 70, 18%), India (n = 47, 12.1%) and Myanmar (n = 23, 5.9.2%). A total of four nematode species (
Neglected intestinal parasitic infections (IPIs) such as soil-transmitted helminthes (STH) have been recognized as one of the main causes of illnesses especially among disadvantaged communities. The last survey of parasitic infections among migrant workers in Malaysia was conducted more than a decade ago. Although it provided useful methodological enquiries, the accrued data were not designed for policy recommendations. Over the last decade, the number of migrant workers has grown exponentially. There is an acute need for accurate information on the epidemiology of parasitic infections and infectious diseases especially as they affect urban communities in Malaysia. A particular gap has been identified in understanding the presence, persistence and epidemiology of infections among longer-term residents and immigrants who have settled in Malaysia. Hence, there is a need for a comprehensive study to establish the composition and transmission of parasitic infections in these communities with a view to developing effective methods of prevention, control and treatment of these infections. Therefore, this study is timely in adopting a scientific approach to address an important public health problem and to provide conclusions that can inform the design of effective public health policies.
Mass migration from less developed to more developed countries have created a shift in the global population. Urbanization and extensive industrialization of developing nations have resulted in millions of migrants travelling to major urban cities around the globe to join the expanding workforces. The International Labor Organization (ILO) estimates that there are approximately 232 million international migrant workers worldwide. Globalization, demographic shifts, conflicts, income inequalities and climate change are some of the influences that drive workers and their families to cross borders in search of better employment and security [
Malaysia is a middle-income country whose economy has transformed into an emerging multi-sector economy and since the 1970s it has been facilitated largely by imported migrant workers. Malaysia has a higher standard of living compared with other neighboring countries in the South East Asian and West Asian region. A total of 74.7% of the population in Malaysia has undergone urbanization with 2.66% annual rate of change (2010–2015) [
Neglected intestinal parasitic infections (IPIs) such as soil-transmitted helminthes (STH) have been recognized as one of the main causes of illnesses especially among disadvantaged communities [
In addition, common human intestinal protozoan infections such as
There is continuous migration of populations from rural to urban areas as well as mass influx of immigrants from neighboring countries to big cities. This sudden influx of people has contributed to the mushrooming of numerous mega urban slums where the environment is conducive for the transmission of intestinal pathogens [
In Malaysia, Suresh et al. [
The current study is timely as in the past decade, the number of migrant workers has grown exponentially with a percentage increase of 49% between 2002 (1.06 million) and 2014 (2.07 million) [
Migrant low skilled and semi-skilled workers can only be employed in Malaysia in five working sectors, namely manufacturing, food services, agriculture and plantation, construction and domestic services. Workers, willing to participate in the current study, were recruited from September 2014 to August 2015 from various agencies and companies around Peninsular Malaysia. A minimum sample size was calculated using a formula by Leedy and Ormrod [
Questionnaires were distributed to participants to gather relevant information related to the study. An individual clinical interview with questionnaire was performed in order to collect individual information including socio-demographic data (nationality, sex, age, religion, marital status, educational level and working sector), migration history (region in country of origin, years of living in Malaysia, mode of entry, working history), environmental health (current residential area, type of accommodation, amenities), life-style habits (smoker, consumer of alcohol and user of illegal drugs), recent episodes of illness (health care utilization, mode of payment, health history) and occupational health and safety (safety hazard, personal protective equipment). In the survey, participants were also questioned on their history of taking anthelminthic drugs. The interview process was performed through an interpreter especially if migrant workers had difficulty in understanding Malay or English. All participants were fully informed of the nature of the study in order to enable maximum co-operation and completion of consent forms.
After consent was obtained and the questionnaire completed, each individual was provided with a plastic container marked with a specific identification number and the name of the participant. The participant was instructed to scoop a thumb size fecal sample into the container, ensuring that the sample was not contaminated with urine. All samples were preserved in 2.5% potassium dichromate solution and brought back to the laboratory at the Institute of Biological Science, Faculty of Science, University of Malaya. For the formalin ether concentration technique, approximately 1 to 2g of sample were mixed with 7 ml of formalin and 3 ml ethyl acetate and centrifuged for 5 minutes at 2500 rpm. After centrifugation, 4 layers were seen, composed of ethyl acetate, debris, formalin and pellets containing parasites. A drop of pellet was taken and stained with Lugol’s iodine on a clean glass slide. The slide was examined under a light microscope at 10x and 40x magnification for helminthes and protozoa, respectively. For
Prevalence data (percentage of subjects infected) are shown with 95% confidence limits (CL95), as described by Rohlf & Sokal [
In the second phase, models were fitted with four environmental factors (employment sector [Construction, manufacturing, plantation, food services and domestic services], educational level [no formal education, primary education only, education to high school level and to university level], accommodation [hostel/employer provided or own/rented] and years of residency [less than one year or more than 1 year] and presence/absence of infections). The most significant of the intrinsic factors detected in the first phase of the analysis was also included and the model re-run as explained above.
An ethical clearance was obtained from the ethics committee, University Malaya Medical Centre, Malaysia prior to commencement of the study (Reference number: MECID NO: 20143–40). All adults provided written, informed consent to participate in the study and a parent/guardian gave consent on behalf of any child participant. Furthermore, all individual tested positive were notified of their condition through their respected employers.
A total of 388 volunteers of migrant workers provided stool specimens. The socio-demographic profile of this subset comprised 304 males (78.4%) and 84 females. Among the males, 37.4% were between 25 to 34 years old (n = 145), 29.4% were younger than 25 (n = 114) and 23.2% older (n = 90 for 35 to 44 years). Most respondents were from Indonesia (n = 167, 43%) followed by Nepal (n = 81, 20.9%), Bangladesh (n = 70, 18%), India (n = 47, 12.1%) and Myanmar (n = 23, 5.9%). The majority were involved in the domestic service sector (n = 105, 27.1%), followed closely by the food service sector (n = 104, 26.8%), while, only a small proportion were from among those working on plantations (n = 71, 18.3%), manufacturing (n = 61, 15.7%) and construction (n = 47, 12.1%) sectors.
Stool screening revealed a high proportion of workers positive for intestinal helminthes and protozoan infections (both helminthes and protozoa combined = 62.9% [56.87–68.55]). There was no significant effect of age or sex, but a highly significant effect of nationality was found (
Prevalence (%) ± 95% confidence limits | |||||
---|---|---|---|---|---|
Factor | Level | N | All parasites | Combined helminthes | Combined protozoa |
Nationality | |||||
Indonesia | 167 | 52.1 [43.07–61.00] | 43.1 [34.48–52.13] | 21.6 [15.04–29.78] | |
Bangladesh | 70 | 52.9 [41.21–64.15] | 45.7 [34.67–57.35] | 14.3 [7.85–24.44] | |
Myanmar | 23 | 56.5 [36.02–75.34] | 43.5 [24.66–63.98] | 21.7 [8.99–43.34] | |
India | 47 | 83.0 [65.67–92.73] | 78.7 [61.18–89.84] | 31.9 [17.57–49.59] | |
Nepal | 81 | ||||
Employment Sector | |||||
Construction | 47 | 59.6 [41.80–75.54] | 53.2 [35.33–69.61] | 12.8 [4.59–28.56] | |
Manufacturing | 61 | 27.9 [19.08–38.37] | |||
Plantation workers | 71 | 53.5 [41.80–64.75] | 49.3 [37.55–61.04] | 11.3 [5.61–20.79] | |
Food services | 104 | 74.0 [70.34–82.50] | 68.3 [61.30–74.59] | ||
Domestic services | 105 | 48.6 [41.41–55.72] | 37.1 [30.49–44.28] | 24.8 [19.12–31.39] | |
Educational Level | |||||
Primary only | 166 | 56.0 [47.04–64.63] | 50.0 [41.00–59.00] | 19.9 [13.50–27.88] | |
High school | 160 | 61.9 [53.09–69.92] | |||
University | 8 | 62.5 [28.93–88.88] | 0 [0–36.46] | ||
No formal education | 54 | 64.8 [54.51–74.15] | 53.7 [43.36–63.57] | 18.5 [11.72–27.77] | |
Accommodation | |||||
Hostel/ Employer | 272 | ||||
Own/rented house | 116 | 47.4 [39.97–54.90] | 37.1 [30.13–44.54] | 23.3 [17.43–30.21] | |
Years of residence | |||||
Less than 1 year | 134 | ||||
More than 1 year | 254 | 54.3 [49.47–59.19] | 47.2 [42.37–52.11] | 20.5 [16.78–24.69] |
Hookworms. The overall prevalence of hookworms was 13.1% [9.56–17.78]. There was no difference between prevalence in male and female subjects (males = 13.2% [9.95–17.19] and females 13.1% [6.51–24.04]), but there was a significant effect of age (
Prevalence (%) ± 95% confidence limits | ||||||
---|---|---|---|---|---|---|
Factor | Level | n | Hookworms | |||
Nationality | ||||||
Indonesia | 167 | 15.0 [9.44–22.47] | 26.3 [19.08–34.84] | 9.6 [5.39–16.16] | 0 [0–3.13] | |
Bangladesh | 70 | 4.3 [1.28–11.81] | 41.4 [30.42–53.04] | 8.6 [3.80–17.41] | 2.9 [0.61–9.70] | |
Myanmar | 23 | 17.4 [6.17–38.87] | 0 [0–14.51] | |||
India | 47 | 12.8 [4.59–28.56] | 68.1 [50.41–82.43] | 2.1 [0.12–14.67] | 2.1 [0.12–14.67] | |
Nepal | 81 | 16.0 [8.44–27.22] | 9.9 [4.44–19.94] | |||
Employment Sector | ||||||
Construction | 47 | 10.6 [3.35–26.30] | 36.2 [21.28–53.89] | 0 [0–10.60] | ||
Manufacturing | 61 | 13.1[7.12–22.05] | 4.9 [1.77–12.06] | |||
Plantation workers | 71 | 14.1 [7.72–24.32] | 25.4 [16.51–36.67] | 15.5 [8.50–25.76] | 2.8 [0.58–9.74] | |
Food services | 104 | 58.7 [51.54–65.54] | 7.7 [4.65–12.40] | 1.9 [0.64–5.11] | ||
Domestic services | 105 | 12.4 [8.33–17.80] | 26.7 [20.76–33.44] | 4.8 [2.46–8.75] | 0 [0–1.96] | |
Educational Level | ||||||
Primary only | 166 | 10.8 [6.22–17.74] | 36.1 [27.93–45.11] | 12.0 [7.30–19.03] | 1.2 [0.18–5.12] | |
High school | 160 | 13.1 [8.06–20.08] | 53.8 [44.94–62.29] | 5.6 [2.70–11.08] | ||
University | 8 | 12.5 [0.64–50.00] | 0 [0–36.46] | |||
No formal education | 54 | 18.5 [11.72–27.77] | 31.5 [22.64–41.77] | 1.9 [0.30–7.26] | ||
Accommodation | ||||||
Hostel/ Employer | 272 | |||||
Own/rented house | 116 | 11.2 [7.14–16.82] | 28.4 [22.16–35.65] | 5.2 [2.69–9.53] | 0 [0–2.17] | |
Years of residence | ||||||
Less than 1 year | 134 | 1.5 [0.36–5.03] | ||||
More than 1 year | 254 | 10.6 [7.92–14.03] | 35.4 [30.90–40.21] | 7.9 [5.60–10.96] |
Three species of intestinal protozoans were recorded.
Prevalence (%) ± 95% confidence limits | |||||
---|---|---|---|---|---|
Factor | Level | n | |||
Nationality | |||||
Indonesia | 167 | 8.4 [4.46–14.88] | 1.2 [0.17–5.13] | ||
Bangladesh | 70 | 2.9 [0.61–9.70] | 10.0 [4.82–19.14] | 2.9 [0.61–9.70] | |
Myanmar | 23 | 13.0 [3.66–32.35] | 8.7 [1.57–27.81] | 4.3 [0.23–21.25] | |
India | 47 | 12.8 [4.59–28.56] | 10.6 [3.35–26.30] | ||
Nepal | 81 | 13.6 [7.00–24.50] | 2.5 [0.38–10.00] | ||
Employment Sector | |||||
Construction | 47 | 2.1 [0.12–14.67] | 8.5 [2.23–23.41] | 2.1 [0.12–14.67] | |
Manufacturing | 61 | 11.5 [6.06–20.22] | 3.3 [0.88–9.62] | ||
Plantation workers | 71 | 1.4 [0.14–7.63] | 8.5 [3.69–17.34] | 1.4 [0.14–7.63] | |
Food services | 104 | 15.4 [10.86–21.19] | 13.5 [9.22–19.01] | ||
Domestic services | 105 | 8.6 [5.31–13.52] | 0 [0–1.96] | ||
Educational Level | |||||
Primary only | 166 | 9.0 [4.99–15.57] | 9.0 [4.99–15.57] | 3.0 [1.00–7.71] | |
High school | 160 | ||||
University | 8 | 0 [0–36.46] | 0 [0–36.46] | 0 [0–36.46] | |
No formal education | 54 | 9.3 [4.69–16.96] | 9.3 [4.69–16.96] | 3.7 [1.17–9.72] | |
Accommodation | |||||
Hostel/ Employer | 272 | 9.6 [6.95–12.97] | |||
Own/rented house | 116 | 7.8 [4.57–12.79] | 1.7 [0.51–5.05] | ||
Years of residence | |||||
Less than 1 year | 134 | 2.2 [0.72–6.15] | |||
More than 1 year | 254 | 10.6 [7.92–14.03] | 7.9 [5.60–10.96] |
With nationality taken into account, the prevalence of all parasitic infections differed between subjects who had resided in Malaysia for less than a year and those who have been there for longer (more than one year;
Analysis of combined helminthes infections by 1-way tests fitting only individual factors with infection in turn (see
Analysis of combined protozoan infections by tests fitting first just each of the environmental factors with infection in turn as above, (see
Hookworms. With host age taken into account, none of the environmental factors affected prevalence of hookworms significantly (
The demand for low and semi-skilled workers in several sectors in Malaysia has seen a dramatic rise in the number of workers entering the country from 1.06 million in 2002 to 2.07 million in 2014 [
Our study identified a two-fold increase of IPIs (62.9%) among workers compared to a decade ago (36.0%) [
Soil-transmitted helminth (STH) (68.3%) infections were more prevalent compared to protozoan infections (25.5%). Of the three common intestinal nematodes,
The demographic profiles of respondents comprised predominantly volunteers from rural areas in their respective countries of origin where IPIs are still very much prevalent and a major concern among the poor and in deprived communities, particularly among workers from India and Nepal where prevalence can exceed 80%. The latest study in the low socio-economic areas of South Chennai, India documented a prevalence of 75.7% with IPI [
Among the significant explanatory factors associated with the high prevalence of parasitic infections in this country were two main factors i.e, the number of working years in Malaysia and anthelmintic treatment. Workers with an employment history of less than a year or newly arrive workers in Malaysia were those who were most likely to be infected. In addition, they were also most likely to have no history of taking any anthelmintic drugs in the last 12 months. The improvements in health shown by the workers with over a year of residency was possibly due to the impact from better quality of life from the provision of clean water and sanitation. In the event an introduction of anthelminthic treatment is implemented on workers upon entry, this can further reduce infection and improve their overall health. This is not surprising as the mandatory medical screening procedure upon entry to this country excludes examination for IPIs and does not require administration of anthelmintic drugs to newly arrived workers [
Transmission of intestinal nematode infections within the community is predominantly dependent on human behavior, particularly during eating and defecation, personal hygiene, and cleanliness. The high prevalence of parasitic infections among the immigrant community sampled in this study provides an insight into the conditions under which the subjects live, and reflects the availability of environmental sanitation as well as the socioeconomic status of this sector of the population in Malaysia [
These findings highlight the urgent need to refine current health polices for Malaysia and especially to include in the future mandatory screening for parasitic infections, as well as STH, of those applying for entry, work permits and residence in Malaysia. Moreover, this should be accompanied by health education campaigns and programs aimed at increasing in the community awareness of the importance of personal hygiene, sanitation, cleanliness and healthy behaviors in controlling parasitic infections [
(DOC)
The authors are very grateful to the Ministry of Health, Malaysia and all collaborators from companies and agencies in Malaysia for giving permission to collect samples. Special thanks also go to all medical staff and nurses from University Malaya Medical Centre and Hospital Universiti Kebangsaan Malaysia (HUKM) for their technical assistance. Most importantly, the authors would like to thank all the migrant workers who have voluntarily participated in this study.