Needles in a smelly haystack

I've been spending quite a lot of time recently in one of the Clinical Research Unit's labs. The research is aimed at understanding more about the epidemiology of Fascioliasis, a parasitic disease which is present worldwide. Fasciola hepatica, and its cousin Fasciola gigantica, are two trematodes (parasitic flatworms) which can accidentally infect humans. They spend their childhood and teenage years in freshwater snails; once they've matured and are ready for the trials of adulthood, they leave the snails and set up camp on aquatic vegetation. There they wait for unsuspecting mammals, such as sheep or cows, to eat the vegetation. Once inside their new host, they spread through the gut and biliary system, where they can mature further and begin to produce eggs which are shed in faeces. The faeces contaminate freshwater ponds, which contain snails, and so the cycle is complete.
Humans blunder into this cycle by eating the aquatic plants from the pond (how clean is that watercress in your sandwich?). Cue abdominal pain, fever, nausea and vomiting and a raft of allergic symptoms. The infection can persist for months until the diagnosis is considered and confirmed; subsequent treatment is with a course of triclabendazole.

Back to the lab. Does F. hepatica or gigantica cause most of the human disease in Vietnam? How much Fasciola is there in the local ruminant population? To answer these questions, we're sifting through the animals' faeces in search of Fasciola eggs, and then trying to extract DNA from them to identify the species. This is actually a lot more fun than it may sound, and is a good way of learning about common molecular biology techniques. Hopefully we will have some results soon; these should help us better understand the disease, eventually allowing us to treat it earlier and more efficiently.

Cholera, really?

On our way past Ward D, Dr Lan rushes up to meet us. "We have a case of cholera!" - she beams at us. The excitement among this pack of infectious disease docs becomes palpable. We ignore an imminent ward round and make our way to see the patient. Images of an exhausted, dehydrated man enter my mind; I cannot help but think of those beds I saw outside the ICU, with a strategically-placed hole betraying their role. I am about to witness one of the great killers of the past 200 years, the plague of urbanisation and poor sanitation, the very disease which led John Snow to father epidemiology in the streets of 1850s' Soho.


We must have entered the wrong room. Sitting on the bed, a colourfully-dressed young lady looks at us, smiling. If we are in the right room, then surely this must be a relative, come to see her dying husband or brother? Not so. This patient came in five days ago, complaining of severe diarrhoea. Within 24 hours of admission, Nature was calling over ten times a day. She became dehydrated and required aggressive fluid resuscitation. Stool samples grew Vibrio cholerae. And then that was it; she just got better. Today she looks absolutely fine and is ready to go home.

The microbiologists are not entirely convinced. They weren't able to isolate that many bacteria from this patient and so we will probably never have a satisfactory answer. Be that as it may; I'm still surprised by how disappointed I was to see such a well-looking patient today.