Infection and immunity
Infection and immunity

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

Infection and immunity

3.5.1  Roundworms, hookworms and anaemia

Pathogenic soil-transmitted roundworms (or nematodes) are transmitted harmlessly from person to person via worm eggs shed into the soil in human faeces. At least 1700 million (or 1.7 billion) people worldwide have these worms in their intestines. Children in heavily infected communities may harbour more than 1000 worms, causing diarrhoea, discomfort and restricting the child’s growth.

  • Can you suggest how children get worm eggs onto their hands and transfer them from hand to mouth?

  • Particles of dirt contaminated with worm eggs stick to the hands when children play or work on soil; if hands aren’t washed before eating, the eggs can easily transfer to the child’s mouth.

Lack of water and soap for handwashing, as well as lack of sanitation, are major contributory factors in hand-to-mouth transmission of all pathogens, not only worms.

Hookworms (Figure 5) are soil-transmitted roundworms measuring 5–10 mm (millimetres), which hook onto the inner wall of the human gut and suck blood from the surrounding blood vessels. Over 400 million people are infected with hookworms and as a result suffer a type of anaemia [an-ee-mee-ah] due to loss of red blood cells. Anaemia caused by hookworms contributes to stunting in children (being short for their age) and wasting (being underweight for their height). Hookworms also present a risk to pregnant women and their unborn or newborn babies due to the adverse effects of maternal anaemia.

Described image
Figure 5  The magnified head of a hookworm (Ancylostoma duodenale), photographed with a specialised (scanning electron) microscope.

The scale bar in the bottom right corner of Figure 5 gives a measurement in micrometres (µm); one micrometre is one-thousandth of a millimetre (mm) and one-millionth of a metre (m).


Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371