Giardiasis in the United Kingdom – current state and moving forward
The latest Paper of the Month for Parasitology is: ‘Giardia duodenalis in the UK: current knowledge of risk factors and public health implications‘ by B. Horton, H. Bridle, C. L. Alexander, F. Katzer
Giardia duodenalis is a type of parasitic organism found throughout the world which causes the disease known as giardiasis in humans, but also within a wide range of warm blooded animals. In 2006 the parasite was added to a list known as the Neglected Diseases Initiative which identifies diseases that are often widespread throughout poorer regions of the world, often in developing countries. Diseases categorized into this list often cause considerable impact on people unfortunate enough to contract them, however are often overlooked by research and when developing methods to combat them. In 2013 it was estimated that over 200 million people worldwide were infected with the parasite, however investigations into the burden and spread of the parasite throughout the world are often limited by lack of knowledge with regards to in-depth biology about the organism, much of which still eludes scientists today. It is however becoming clear that the parasite can cause a wide range of symptoms, both in the short and long term, and that occasionally life long complications can arise due to infection. When this happens within impoverished communities of the world it adds further strain to an already challenging lifestyle, reducing an already low quality of life.
As mentioned, the parasite has worldwide prevalence, meaning that it is also seen within the UK. Previously it has been estimated that around 4000 people per year are identified as having contracted the disease throughout the United Kingdom. Infection has also been found to differ depending on the biological characteristics of the parasite, which can vary even within the species duodenalis. These differences, termed ‘assemblages’ further complicate an already complicated disease story.
Disease is contracted when parasite cysts, shed in an infected hosts faeces, are unknowingly ingested by a new host. Infection has been identified to come from various sources, such as contaminated food, water-sources and interactions with various animals. Some of these routes of infection have been discussed within this review in an attempt to highlight their role within the spread of the disease. The review gives an up-to-date overview of the current state of giardiasis knowledge, leaning towards Public Health within the United Kingdom. It also highlights the differences that are seen between English/Welsh and Scottish surveillance results by Public Health bodies and presents reasons as to why this might occur within a seemingly relatively close population.
To promote and assist future research, we end the review by suggesting key recommendations which should be employed going forward. We feel these recommendations would be of huge benefit to establishing best practice guidelines and standardization of research within the field. Employment of these would allow accurate comparisons between data generated by future work, which is often an issue when drawing conclusions on the subject. In doing this, it would also guide towards a broader view of the epidemiology of the parasite, which looks increasingly to be dependant on both large and small scale ecosystems, and their interaction between each other and with humans populations.
The paper ‘Giardia duodenalis in the UK: current knowledge of risk factors and public health implications‘ ia available free for a month.