The Dinosaur Feather

vast majority of cases, the tapeworm is discovered by chance, during an operation or an autopsy. They normally grow two to four metres long, and when a tapeworm is discovered, the host is given medication that kills the tapeworm and it’s expelled from the host with faeces. Unpleasant, certainly, but as I said, quite harmless.’
    Søren was close to retching. At the same time his brain was troubled by a discrepancy.
    ‘I’m not sure I quite understand,’ he stuttered. ‘ProfessorHelland didn’t have a tapeworm, but carried . . .’ Søren checked his notes, ‘cysticercus.’ Dr Bjerregaard waited patiently.
    ‘That’s correct. However, I haven’t finished my account,’ she said calmly. ‘The life cycle of parasites is a complex area, even for a great many biologists, and in order for you, as lay people, to understand what I’m telling you, I need to give you some basic information.’ She suddenly looked at the two men, as though she was enjoying herself tremendously.
    ‘Yes, of course. Sorry,’ Søren said. Henrik looked sick.
    Søren expected Dr Bjerregaard to launch into the second half of her disgusting lecture, but she merely said, ‘The logical conclusion is . . .?’ She looked sternly at the two men.
    ‘That Helland ate shit,’ Henrik blurted out. ‘Gross.’
    Søren glared at Henrik.
    ‘It means,’ he said, addressing Dr Bjerregaard, ‘that Helland somehow ingested a tapeworm egg.’ On realising the implications, he fell silent.
    ‘Or, to be precise, 2,600 eggs,’ Dr Bjerregaard interjected. ‘If that’s the number of cysticerci Bøje found in the tissue of the diseased, then it would equal 2,600 eggs.’
    Søren managed to suppress his revulsion to such an extent that he could follow her logic. ‘But he didn’t ingest a whole . . .’ he checked his notes again, ‘proglottid?’
    ‘That would be impossible to know.’
    Søren detected a microscopic smile at the corner of her mouth.
    ‘If the proglottid carried more than forty thousand eggs, you would have expected many more than 2,600 cysticerci. However, there might be several factors why only 2,600managed to develop.’ She shrugged. ‘The point is that Lars Helland acted as the intermediate host, and that happens very rarely in these latitudes. During my thirty years here, I’ve only come across three cases of human intermediate host infection, and they were all discovered in people who had recently returned from countries with a high prevalence of
Taenia solium
, such as Latin America, non-Islamic Asia and Africa. Do you know if Helland spent time in a high risk country?’
    ‘We’ll be checking that. The parasite theory is still very new to us,’ he said, by way of apology, and continued, ‘How can you tell how long the cysticerci have been in Helland’s tissue?’
    ‘The host body forms calcium capsules around the cysticercus, to protect itself from the foreign object, and in the capsule, the cysticercus awaits its next developmental stage. You can determine the exact age of the cysticercus by measuring the thickness of the calcium shell. This would normally take place in pigs, which will be eaten sooner or later, and this places an upper limit on how calcified the capsule becomes. However, humans are unlikely to be eaten, aren’t they? The growth of the cysticercus is generally very slow, and as Helland’s cysticerci were fairly large, I would estimate that they’d developed over a long period of time. The capsules were thick and the cysticerci would undoubtedly have demanded more and more room. To begin with, they would have caused Professor Helland only mild irritation, but in time they would have become a pathological condition and I can’t imagine how he coped with it. Cysticerci have a preference for the central nervous system,and from records – from Mexico, for example, where the occurrence of humans infected with cysticerci is high – 82 per cent of cysticerci had attached themselves to nerve tissue. Otherwise they prefer muscular and subcutaneous tissue, in that order.’
    ‘What about symptoms?’ Søren asked. Bjerregaard pursed her lips.
    ‘The symptoms of an infected patient depend on several factors. Generally, you’ll expect to find a positive correlation between the number of cysticerci and the extent of the symptoms. However, it depends on where the cysticerci are located. Forty thousand cysticerci located exclusively in muscle tissue can, in theory, cause less damage to their host