10 year follow-up study on Giardia patients in Bergen

Researchers are now set to assess quality of life and chart pain levels, abdominal complaints and symptoms of chronic fatigue.

By Andreas R. Graven

The parasite Giardia lamblia. (Photograph: CDC / Janice Haney Carr)

A questionnaire was distributed during the first two weeks of 2015 to a selected group of 1,252 persons who were independently confirmed from a laboratory test as having been infected with the Giardia parasite.

A control group made of persons not infected by Giardia received the same questionnaire, in order to provide comparison of results.

The researchers estimate that at least 2,500 persons in Bergen were infected with Giardia, resulting in an upset stomach and vomiting, when the source of drinking water known as Svartediket was polluted with sewage in the autumn of 2004.

Researchers continue to chart the condition of those infected with Giardia ten years after the event, due to the fact that the number of long-term complications has been high.

Numerous persons struggle with health for years
Two former follow-up studies – three and six years after the infection – have shown that numerous people struggle for years with health complaints such as chronic fatigue and irritable bowel.

Professor Guri Rørtveit.(Photograph: Rune Rolvsjord) 

In the new study now ready for execution – the third follow-up study in Bergen after the Giardia epidemic – the researchers will not only assess the number and severity of health complaints, they will also evaluate the study participants' perceived quality of life.

"Our aim is to discover whether the people who suffered from irritable bowel syndrome and chronic fatigue recovered, and whether those who were infected with Giardia take longer to recover from this type of illness than those who were not infected," explains Research Leader and Professor Guri Rørtveit from Uni Research Health's Research Unit for General Practice.

Guri Rørtveit is in charge of the upcoming study that will gather data for the 10-year follow-up.

The study will be executed as a cooperative project between the Research Unit for General Practice in Bergen, the University of Bergen and Haukeland University Hospital.

Long-term medical complications
"We want to investigate whether there is a difference in the correlation between health problems such as irritable bowel syndrome and fatigue, and quality of life in the two groups. We also want to study the correlation between such health problems and other medically unexplained symptoms," continues Guri Rørtveit. 

She has been surprised by the results of the former studies, which show that a high number of people still suffer health problems as long as three and six years after the infection.

"In principle, we did not believe the Giardia infection would have such long-term consequences," she confirms.

Long-term medical complications have been an unknown factor for researchers, until the epidemic and studies in Bergen.

"This is very important knowledge, because Giardia is a parasite that affects a large number of the world's poorer population, in areas where the health service is of a much lower quality than we have in Norway and Europe," Guri Rørtveit explains.

Genetically vulnerable to long-term ailments? 
For the 10-year follow-up questionnaire, a number of questions that have already been clarified with the previous questionnaires have been removed – for example on issues such as sleep, incontinence and asthma/allergies. These will be replaced by questions relating to quality of life and pain.

A number of participants will also be asked to submit a saliva sample. These samples will be stored in an approved biobank at Haukeland University Hospital for subsequent genetic analysis. Irritable bowel syndrome and chronic fatigue are conditions with a number of unknown factors.

The researchers have shown that the Giardia infection can trigger such symptoms, but there is little knowledge as to why some people have long-term problems while others recover after a short time. Genetics may provide an explanation.

"We are only taking samples from the persons in the Giardia group, so that we will be able to investigate whether they are genetically vulnerable to long-term health problems after being infected with Giardia. However, we do not expect to find changes in individual genes that are predictive of irritable bowel syndrome as a complication of a Giardia infection," confirms Guri Rørtveit.

Three and six years after infection
The proportion of participants who have replied to the former studies has been high, with about two thirds of the Giardia group actively participating. 

Three years after the Giardia outbreak, a total 46% suffered from irritable bowel syndrome, with a corresponding percentage of 14% in the control group. Six years after the epidemic, the researchers found that the percentage of irritable bowel syndrome remained high (39%).

The result of the three-year study showed 42% with chronic fatigue, with a corresponding 12% in the control group.

Six years after the infection, 31% had chronic fatigue. It is important to underline that this is not the chronic fatigue syndrome diagnose, which is based on extensive medical examinations.

In 2004, the drinking water source in Bergen, Svartediket, was infected by the Giardia lamblia parasite. At least 2,500 people suffered from diarrhoea and abdominal pains as a result. Many have struggled with abdominal complaints and fatigue since then, results from the follow-up studies show.

The outbreak in Bergen is one of the largest known on a worldwide basis.

The research carried out in Bergen after the outbreak has provided a number of answers that can help understand the long-term consequences of Giardia infection. This new knowledge is of great value for all those who are infected with Giardia every year worldwide.

G. lamblia is a parasite that lives in the small intestines of those infected.  Infection is via drinking water and faeces. At any given time, several million people are infected, mostly in low-income countries.

Jan. 8, 2015, 10:49 a.m.

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