There are many reasons why doctors recommend that visitors to Asia or Africa should always drink bottled water. One reason is that drinking water in Asia or Africa often contains the eggs of parasites – which can be an uncomfortable companion to bring back from a holiday or business trip.
The parasites develop and grow in your intestines and some of them can become as thick as a little finger and up to 10 cm long. Others suck blood from the walls of the intestines, while yet another type works its way into the intestinal walls and eats the walls’ tissue.
In Denmark and other western countries your doctor will prescribe medicine that effectively kills the parasitic worms – but you do not have that possibility if you are a poor peasant in Africa or Asia. Here, the parasites can live in your intestines for a long time, resulting in great reductions in your quality of life and ability to work.
“Parasites can accumulate in the intestines, resulting in many complications,” says Mita Eva Sengupta, of the University of Copenhagen’s Department of Veterinary Disease Biology/Parasitology, Health and Development, who has just defended her PhD thesis on parasites.
“Some people can develop anaemia if they have too many blood-sucking parasites in their intestines. Parasites can also provoke an immune response or prevent the intestinal walls from absorbing nutrients – a severe problem for people who are already fighting to get enough food,” she says.
“And parasites have also been associated with a poorer ability to learn. So parasites are a gigantic problem in developing countries and we want to do something effective about the situation.”
In her thesis, Sengupta suggests that the problem with intestinal worms can be reduced using a new extract that she has developed.
From faeces to food:
Toilets and proper sanitation do not exist in many developing countries, so faeces containing parasite eggs often end up in lakes, rivers and other watercourses.
People can digest parasite eggs when they drink or bathe in this water.
In addition, dirty water is often used to irrigate crops. In this way, the parasite eggs can be transferred to food and then infect people.
The extract, which derives from a widespread tropical tree, causes the eggs of the worms to fall to the bottom of a stretch of water, so the eggs do not wash out on to crops and the like and from there to people.
“Parasites cause great problems around the world,” she says. “Parasites are not only transmitted to people when they drink contaminated water but also when they eat uncooked crops such as tomatoes and lettuce – in many countries, farmers often irrigate their land with untreated wastewater, so the parasite eggs enter the intestines in this way.”
In her research, Sengupta studied how parasite eggs behave in water, and she found a handy way of preventing the parasites from being transmitted to crops.
One of the things she studied was how quickly the eggs settle to the bottom of a stretch of water such as an irrigation channel and how quickly they return to the surface layer of the water if there is a current along the bottom of the watercourse.
These are the first-ever results of such a study and they can be used to improve our understanding of how parasite eggs settle in streams, artificial irrigation channels and wastewater treatment plants.
If the eggs fall to the bottom of the watercourse, they do not enter the drinking water – so the faster they settle, the better.
Sengupta studied how parasite eggs settle in both clean water and dirty water containing large amounts of particles such as mud, algae, plant remains and minerals.
It is not only in developing countries that farmers use wastewater for irrigation – Italy, Spain and several Eastern European countries also use wastewater.
Eggs from tapeworms in the wastewater can be transferred to crops and infect people.
“We knew absolutely nothing about how parasite eggs behave in different types of water,” says Sengupta.
“Wastewater treatment plants aim at reducing the amount of nutrients in the water as much as possible, but they have very little knowledge about how infectious agents – and in particular parasite eggs – are affected by the purification processes. There is thus room for improvement in wastewater treatment.”
Following her studies of parasite eggs in different water qualities and flows, Sengupta carried out laboratory tests to find a method to get the eggs to fall to the bottom more quickly from the surface layers where they are more likely to infect people directly, or indirectly through crop irrigation.
Sengupta found a suitable method in the seeds of the tree Moringa oleifera – its English common names include moringa, benzolive tree and West Indian ben; it is also known as drumstick tree (from the appearance of its long, slender, triangular seed pods), horseradish tree (from the horseradish-like taste of the roots, and ben oil tree (from the oil derived from its seeds).
The tree is found everywhere in the tropics, and the extract from its seeds binds particles together in water, so they settle more quickly.
The extract is easy to prepare, as it is simply a matter of grinding the seed capsules to a fine powder, adding the powder to water in a soft-drink bottle and shaking the bottle thoroughly. After it has been filtered through a piece of cloth, the extract is ready for pouring into polluted water.
Here, the extract works as a coagulator, collecting mud, algae, plant remains, minerals and parasite eggs in large lumps, which quickly fall to the bottom.
Moringa oleifera is a so-called multi-purpose tree as it has many uses.
The seeds can be used to cleanse water, the seed capsules can be eaten, the leaves can be used as animal feed, and the tree itself can be used as fuel.
Parasite eggs in water treated with the Moringa oleifera seed extract settle almost twice as fast as they do in water not treated with the extract.
“My trials show that it is easy for the individual farmer to make the seed extract, and it works well,” says Sengupta. “A farmer can use the Moringa oleifera seed extract in water collected in a barrel and then use the water to irrigate his crops without the risk of transferring the parasite eggs to the food that his family must live from. In addition, the Moringa oleifera seed extract is quite harmless to people.”
Sengupta’s research also showed that the dirtier the water, the more effective the seed extract is in getting the parasite eggs to settle.
The next step on the path to helping the more than one billion people suffering from intestinal worms is trialling the Moringa oleifera seed extract in the real world. Sengupta plans to travel to Ghana and conduct real-life seed extract trials with some of the country’s farmers.