For many of us, intestinal parasites might seem a relic of the past, consigned there by the vast improvement in sewerage and sanitation facilities, and personal hygiene practices, in the country since Independence.
However, such infections by worms and protozoan parasites are still an important public health problem among disadvantaged communities like the Orang Asli and Orang Asal, the rural poor in estates and villages, and the urban poor in squatter areas, particularly among children.
A 2011 review published in the Southeast Asian Journal of Tropical Medicine and Public Health reported that 25 studies conducted between 1978 and 2007 in a variety of the above communities found that the incidence of worm infections ranged from 36.3% to 100%.
However, there is another community in the country, which is presenting a new front in the war against intestinal parasites: migrant, or foreign, workers.
According to Human Resources Minister Datuk Seri Richard Riot Jaem, there were 1.8 million registered, or legal, migrant workers in Malaysia as of last December.
The top four countries supplying these migrant workers are Indonesia, Nepal, Bangladesh and India – all nations, like Malaysia, that have endemic intestinal parasite problems.
While legal migrant workers undergo a health screening before they enter the country, it does not check for infections of intestinal parasites.
Says University Malaya (UM) parasitologist Associate Prof Dr Siti Nursheena Mohd Zain: “Yes, they are screened for HIV, malaria, STDs (sexually-transmitted diseases), TB (tuberculosis); however, we don’t screen them for parasitic diseases.
“And these parasitic diseases are important as they can be passed to others.”
So, how serious is the problem exactly?
A study led by Assoc Prof Siti Nursheena last year found that over three in five (62.9%) of the 388 legal migrant workers here whose stool samples they collected were infected by intestinal parasites.
Of the five nationalities in the study, Nepali workers were found to be the most likely to be infected, with 84% of them carrying one or more intestinal parasites, followed closely by workers from India at 83%.
The least likely workers to be infected were the Indonesians at the still-high rate of 52.1%.
The parasites that were checked for in the study included roundworms, whipworms, pinworms, hookworms and tapeworms, as well as the protozoan parasites Entamoeba histolytica, Giardia sp and Cryptosporidium spp.
Infection rates were 79.1% among those who had been in Malaysia for less than a year, but were less at 54.3% among those who had been here for more than a year.
“That may indicate that these infections are brought from their home,” says UM Faculty of Medicine deputy dean for research Prof Dr Yvonne Lim Ai Lian, who was also involved in the study.
The decrease in infections among those who have been in the country longer is probably due to better facilities and hygiene practices, says Assoc Prof Siti Nursheena.
“In Malaysia, all of the workers who were employed were given good basic facilities – there are proper toilets, there’s clean water – because of that, the infection could clear off,” she says.
She believes that most of the workers are unaware of their infection because they do not experience any symptoms – a common situation with mild infections.
Transmission and treatment
The three types of parasites in the study published last November in the journal PLOS Neglected Tropical Diseases, pass from one person to another via the oral-faecal route.
Eggs from soil-transmitted helminths like roundworms, whipworms, pinworms and hookworms, need to incubate in soil for three weeks once they pass out from an infected person via their faeces.
Infection with these eggs can occur by eating vegetables that have picked up the eggs from contaminated soil, drinking water contaminated with the eggs, or by touching the mouth with hands that have touched contaminated soil with the eggs.
In addition, hookworm eggs can hatch in the soil into larvae that can penetrate the bare skin of those that come into contact with them, for example, by walking barefoot or playing on contaminated soil, or gardening without gloves.
Tapeworms and protozoan parasites are also passed out from an infected person via their faeces and infection occurs when another person eats or drinks something contaminated with the faeces.
This is especially worrying as a significant number of migrant workers are in the food and domestic services industry, bringing them in direct contact with food and drinks.
The UM study showed that 74% of the participants in the food services sector and 48.6% of domestic services workers were infected with intestinal parasites.
Most, if not all, of the nationalities involved also practice cleansing with their hands and water after passing motion – a habit that may exacerbate the transmission of intestinal parasites, if they do not wash their hands thoroughly with soap and running water afterwards.
In fact, another study, also conducted by Assoc Prof Siti Nursheena with other colleagues, showed that 12.3% of the 383 migrant food handlers they interviewed did not wash their hands using soap and warm running water before preparing food, while 1.3% did not know if they needed to do so.
This study, published in the journal Food Control last May, found that the average score for the 20 food safety knowledge questions these food handlers were tested on was 31.1%.
However, they scored a average of 69.8% for food handling practices, which included items like smoking in the food preparation area (97.4% say no), wearing gloves during food preparation (44.4% say yes), and covering hand wounds with bandages during food preparation (39.9% say they don’t know).
These migrant workers were from a variety of eateries like mamak shops, hawker stalls and restaurants in Kuala Terengganu in Terengganu, Shah Alam in Selangor, and Ipoh in Perak.
Less than half of them (47.3%) had attended the compulsory course for food handlers by the Health Ministry, although more than two-thirds (68.9%) had a valid typhoid vaccination certificate.
Assoc Prof Siti Nursheena points out that the low scores in the study were in spite of the fact that she and her team had come up with graphical representations of the questions and had the aid of translators to overcome the language barrier between themselves and the workers.
“This will relate back to the (ministry’s) course.
“Yes, they attended, but the knowledge was not acquired,” she says.
“So the recommendation we want the Government to look into is to have the course in the workers’ own languages.
“Or, at least send someone like their mandur (foreman), who has been here longer and understands Bahasa Melayu, so that they can go back and teach those under their supervision.”
Another recommendation by the researchers is mass drug administration for intestinal parasites to new migrant workers.
“The mass drug administration should be guided by which country the workers are coming from, as there are some countries that are endemic for certain illnesses that are already known,” says Prof Lim.
She adds that due to the inexpensiveness of anti-parasitic drugs like albendazole, companies like community pharmacies or those employing a significant number of migrant workers can consider providing such drugs for free as a corporate social responsibility project.
She also says that screening for intestinal parasites should ideally be integrated into the compulsory health screening all migrant workers undergo for long-term efficacy.