Some of the things lecturers say make a lasting impression on students' memories (albeit not always for the desired reasons). I remember, when I was a biology undergraduate, hearing about some of the undesirable effects of filiarid worm infection. According to the lecturer, in extreme cases this could lead to infected men having to 'carry their balls in a wheelbarrow'. At the time we found this painfully funny (although I imagine some of the guys crossing their legs in sympathy) but at the same time I did wonder if this wasn't just a case of exaggeration for effect :-) But in the age of google, I can report that it was not; well, not exactly. (Warning: persons of the male gender may find what follows a little unsettling....)
Filarids are parasitic nematode worms that are the cause of significant & at times disfiguring disease (filariasis) in humans & other animals. They're classified according to the part of the body that they inhabit. Some live in the lymphatic system. Others are found in the subcutaneous layers of the skin, & still others in the abdominal cavity, & all but one species are transmitted by blood-sucking insects. The species that live in the lymphatic system can lead to elephantiasis, which can affect up to 10% of the population in at-risk tropical areas.
This disease is named for the appearance of the legs (usually) & lower body of infected individuals. The filarid worms tend to live in the lymph system, often congregating in the lower part of the body although arms & breasts can also be affected. These aren't small creatures: while the thread-like males are only 0.1mm in diameter they're 4-5cm long, and the much larger females are about 10cm in length & 0.3mm wide. So you can see that a large number of them could seriously block the drainage of lymph from the legs & abdomen. This means that there's effectively a back-up of lymph in the tissues below the blockage, which leads to tissue swelling (oedema) & eventually discolouration & thickening of the skin. I hasten to add that this doesn't develop overnight & an affected individual has usually been exposed to - & bitten by - infected mosquitoes for several years.
Where does the wheelbarrow come in? Well, blockage of lymph flow in the lower body won't affect just the legs. And my lecturer of long ago wasn't just telling an apocryphal story,as the World Health Organisation's web page attests - but he may not have been right on the money either, as filarid infection isn't the only cause of elephantiasis. For example, in 2005 Daniel Kuepper reported on a case of giant scrotal elephantiasis due to a genital infection called lymphogranuloma venereum. In this case the patient's scrotal sac was grossly enlarged, measuring 80 x 40 x 40 cm & weighing around 42kg. This unfortunate man had been immobile for 5 years before Kuepper saw him, & his spine had been irreversibly damaged by the extra weight he'd been carrying below his centre of gravity, while he could still get around. Kuepper & his medical colleagues ended up performing a fairly major & painstaking operation that removed the mass of tissue (& - unavoidably - his testes) while saving his penis: it was a tribute to their skill that he regained the ability to experience erections in addition to being once more able to move around freely. (I was surprised to find quite a number of similar case reports while I was reading around for this story.)
While I think of it: Joseph Merrick (aka 'the Elephant Man') didn't have elephantiasis but was afflicted by the even more disfiguring (& extremely rare) Proteus syndrome. The film The Elephant Man is a moving look at this man's short & difficult life, which must have been made all the harder by the attitudes of many of those with whom he came into contact.
And yes, I do tell this story to my own students. But I'm careful with the pictures; I had someone faint once when I showed an image of a blood-swollen leech, & I'd prefer to avoid that sort of thing if I can :-)
D.Kuepper (2005) Giant scrotal elephantiasis. Urology 65:389.e19-389.e21.