The Mekong Delta: a public health nightmare

The Mekong Delta is a vast and beautiful expanse of waterways in southern Vietnam. Having travelled over 4,000 kilometres from China, taking them through all the countries of South-East Asia, the waters of the Mekong spread out over much of the land south of Ho Chi Minh City. Arriving by night, each river crossed makes me think of the next tentacle which a dark octopus might be trying to block our route with.
By day, a vibrant, bustling hive of activity takes shape as the sun rises. Everybody here owns a boat. For some it is also their home. For all it is their way of making a living, taking them and their wares to the many floating markets of the Mekong. There are some laden with mangoes, bananas, watermelons or pumpkins; ice or rice; clay hearths or charcoal; and bread or pho, to cater for the morning munchies.
The river however is much more than an aquatic road to the nearest market. Most of the homes here have a back door which leads straight out onto the brown, murky Mekong waters. This is where clothes are washed, pots and pans are rinsed and litter is discarded. Children play in the lukewarm waters while teenage girls clean their bicycles nearby. A man lowers a bucket into the shallows to collect a little water to brush his teeth with. A young woman crouches down on a ledge, washing her long, dark hair in the river. The Mekong is everything to the people here: every activity involves its waters at some stage.
Drifting along in a small boat, I cannot help but think of all the other creatures which populate this river. Countless bacteria, viruses and parasites thrive in the warm, humid environment provided by the Mekong, repeatedly introduced there by humans and other animals. Hepatitis A, typhoid fever, cholera.... the list is long and frightening.
The waters of the Delta are a public health nightmare. The question is, how can one go about changing some of the behaviours of those whose lives depend on this river? Where should a benevolent Health Minister start? Try as I might, I cannot imagine that the situation here could change until there is a realistic alternative way of life for all the people who are born on the Mekong and only know how to survive thanks to its waters.

Avoid the snails, they're fresh.

One of the attractions of infectious diseases is that there is usually a high turnover of patients. As a general rule, treatment brings about a rapid improvement and patients can return home within a few days, even if they will be receiving on-going treatment for a longer period. My experience at the Hospital for Tropical Diseases has reflected that so far: most patients have been on the wards for only two or three days.
The Viet Anh (Vietnamese-British) ward specialises in neurological infections however, and as such defies the rules. Some patients arrived here before me and unfortunately it looks like they will stay here long after I've left. One of them hasn't moved since my first ward round. He lies on his back, eyes wide open, a ventilator and tracheostomy apparently keeping him alive. The only sign of life is the perpetual twitching of his left cheek, which causes a little foam to form at the corner of his mouth.
A few months ago, he and his twin brother were working in a field outside of Ho Chi Minh City. Pausing for lunch, they noticed the pond nearby was full of snails and didn't think twice: a few raw gastropods and back to work. Unfortunately, the snails were carrying the roundworm Angiostrongylus cantonensis. This parasite usually lives in the lungs of rats, but regularly makes excursions to their gut. Once excreted into the open world, it then relies on snails and slugs to ingest it so that it can develop into new, fully-infective larvae which can colonise new rats.
As is often the case with such worms, humans are only an "incidental host" (see Half a Brain). They become infected by eating raw or under-cooked snails and slugs, or vegetables contaminated by them. Having invaded a new host (be it a human or a rat), Angiostrongylus travels first to the brain and causes an inflammatory reaction which is characterised by the presence of a specific type of white blood cell: this is eosinophilic meningitis, and this is what brought our two brothers into hospital.
Though they both suffered from headaches, nausea and vomiting, neck stiffness and the occasional seizure, only one of them had read the textbook. He got better after a fortnight, and returned home. His brother, however, slipped into a coma and he is still there now. Most patients with eosinophilic meningitis make a full recovery; it is extremely rare for it to cause brain damage as it has in this case.
At this stage, after such a long coma, there is little cause for optimism. He may yet make a miraculous recovery, but it is unlikely. His family will eventually have to decide whether they wish to keep paying for him to receive supportive treatment in hospital, or whether they would rather he came home and were released from his bodily prison.
His brother, with whom he shares so much, reminds us that when two similar people are infected with the same parasite, the outcome can still vary enormously. We still have a lot to learn about the factors which dictate who will be the lucky ones. And we still have a mountain to climb in order to prevent poor, hungry people from eating a quick, easy and free lunch.