It's Closer Than You Think...



Posted by Jeremy Windsor on Jul 09, 2021

Giardiasis is something you get on exotic foreign holidays. Right? Wrong! In the UK there are more than 3000 cases reported each year. Whilst some originate overseas, large numbers are acquired here. Recently, we spoke to Ian Makkison, Consultant Anaesthetist at Chesterfield Royal Hospital, about his experience of the disease. As you'll see, things didn't go quite to plan...


Most probably I caught my Giardiasis from swimming in the River Derwent, somewhere between Calver Bridge and Froggatt Bridge, a distance of approximately a kilometre. It is a section popular with swimmers and may be known to climbers as it features in Andy Cave’s book “Learning To Breathe”.

The incubation period is between 1 and 21 days, depending upon the quantity of cysts ingested. During that period I had swum in the Solent at Seaview and surfed at Freshwater Bay. However it is rare to catch Giardia from sea water as saline often destroys the cysts. I also swam in public pools, but since the cysts can only survive for a few minutes in chlorinated water, this seems unlikely too. Therefore the Peak District looks like the most likely source! 


Giardiasis is caused by ingesting Giardia Duodenalis cysts from contaminated water or food, or by direct contact with infected humans or animals - including pigs, sheep, horses, dogs and cats. Whilst dormant, the cysts can remain infectious in cold water for 3 months. Once ingested the cysts transform into active organisms (trophozoites) and rapidly multiply


After 5 days, I started with loss of appetite, nausea, lethargy and belching. This got progressively worse to the extent that I was struggling to complete my daily cycle commute of only 4 miles. Bending over to pick up the dogs’ ball was associated with retching. As a typical hypochondriacal doctor I had diagnosed myself with stomach cancer. So did one of my surgical colleagues when he developed symptoms. He went one step further and had a “top and tail” endoscopy after drinking water contaminated with Giardia from an alpine stream. His non-medical walking partner recognised the symptoms and eventually persuaded him to go to his GP and save the NHS the cost of a long list of further tests!

Eight days later, I started to vomit and have profuse diarrhoea, without a temperature. This differed from Campylobacter, which I caught in Kashmir in 1982 and then again from my hens 5 years ago. With Campylobacter, the first symptoms were associated with a high fever and some bloody diarrhoea. 

I took stool samples in to the hospital the following day, a Sunday, and was rung by the matron in charge that afternoon. Apparently the microbiologist had never seen so many cysts and trophocytes of Giardia, in one single sample before. I was subsequently told that it was so good (or bad) that they had frozen my sample for teaching purposes!

I obtained some Metronidazole (400mg 3 times a day) and the vomiting stopped after 4 days and the diarrhoea a day later. The course finished after 7 days but 2 days later the diarrhoea and vomiting started again. The following day I had Giardia confirmed on a stool sample, and started a 10 day course of Metronidazole, after discussing myself with the local microbiologist. (Metronidazole has a 60% success rate). A day later the diarrhoea stopped and I went back to work 4 days later, with the approval of the infection control team. However 3 days after completing the 10 day course the diarrhoea and vomiting returned. 


A systematic review for the Cochrane Database concluded that albendazole (400mg once daily for up to 10 days) may have similar effectiveness to metronidazole (250-500mg 3 times a day for up to 10 days) in treating giardiasis. Importantly, albendazole has fewer side effects and a more simplified dosing regime than metronidazole.


The local microbiologist suggested that I attend the infectious diseases unit at the Royal Hallamshire Hospital in Sheffield so that I could obtain a medication which could not be prescribed in Chesterfield. Eight days later I was seen as an out patient and started on Tinidazole and Albendazole. The combination therapy has a 60% success rate in Metronidazole-resistant cases. This stopped the diarrhoea and vomiting after 2 days. Two days later the diarrhoea stopped and I went back to work 3 days later.  

Unfortunately, 8 days after the antimicrobials were stopped I started to develop loss of appetite and nausea once again. Three days later I had diarrhoea and vomiting again, to the extent that I vomited an hour after each of the 6 snacks and meals I had that day. Once again the Polymerase Chain Reaction (PCR) machine confirmed Giardia. Four days later I was seen by the infectious diseases team again and started on the definitive treatment of Mepacrine. This old anti-malarial has a 100% success rate but carries a 1 in 200 chance of developing acute psychosis, so is not used first line. Fortunately, the Mepacrine worked!


In 2012, an organised 2.25 mile swim along the River Thames attracted considerable attention after more than 300 swimmers reported gastrointestinal symptoms in the days following the event. Of 9 swimmers who submitted stool samples, 2 were found to have developed giardiasis. The study is published here


This infection started on the 15/9/19 and I finally stopped all medication on the 30/11/19 - a period of approximately 79 days. Throughout this period and for 3 months afterwards, I had altered taste, belching, anorexia and nausea. Giardia is known to cause indigestion, which can persist for months after the infection has ceased and can cause lactose intolerance. These symptoms made it difficult at times to know if I had been cured. 
I lost a total of 11kgs in weight after being a reasonably fit 84kg and 1.85m tall male at the outset. I lost all interest in chocolate along with many other foodstuffs. How much this was due to the drugs and how much to the Giardia I cannot say. All alcohol tasted disgusting for 2 months after the illness stopped. I did not try to drink whilst on medication, but did hear from one of our local physicians who told me that he came back from India with Giardiasis and Amoebic Dysentery. He tried drinking 36 hours after stopping a prolonged course of Metronidazole and spent 2 days vomiting.

I have now returned to wild “dipping” rather than swimming. I no longer put my head in the water and swim properly, and no longer try to swim any distance.


Thanks Ian for sharing your experience!

Further information on Giardiasis in England and Wales can be found here.

You'll find lots of other interesting mountain medicine case studies on the blog  - including strokehepatitis E, influenza and even bed bugs!

Interested in dentistry in the mountains? Take a look at this!

The Birmingham Medical Research Expeditionary Society (BMRES) and the British Mountain Medicine Society (BMMS) have joined forces to organise the 2021 Altitude Research Conference. The face-to-face event will take place in Birmingham on the 11th September. Speakers will include Peter Bartsch, Jo Bradwell and Chris Imray. There will also be presentations from members of the UK's leading research groups as well as ample opportunity for researchers, young and old, to present posters and short talks about their work.

Further details can be found here.


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