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Giardia and risk

joost zaat jzaat at pi.net
Sun Mar 31 16:12:26 EST 1996

Michael Casteel <Arhat at gnn.com> wrote:

>Somebody, anybody tell me what you think. Using Giardia lamblia as 
>an example, do you think that risk of exposure to this organism has 
>decreased since the 1960s due to an increase in our knowledge of 
>the biology, control/prevention measures (i.e., water treatement 
>processes), etc. that we have gained since that time? That is, 
>would risk be inversely proportional to knowledge of the risk? What 
>I am interested in is if you think there is a relationship between 
>the two. If there is, do other factors, such as socioeconomic ones, 
>make a possible relationship insignificant? I hope Dr. C. Haas 
>reads this and responds.

One of the problems in the l;iterature is often the lack of
information of the studied population and the used laboratory
techniques to diagnose giardia infection. 
As far as I know there is a 'background' incidence of +-5% in western
countries. Reported date differ from contry to country  in 1991 the
incidence in Italy was 32/1000 in adullts with acute diarrhea (
Libanore M et al. Incidenza della giardiasi in pazienti adulti con
entrerite acute. Minerva medica 1991;82:375-80). However in Copenhagen
(danmark) the incidence was 81/1,000,000 (Heljt K et al . Giardiasis
causing chronic diarrheoa in suburban Copenhagen. Acta pediatr 1992;

A lot of infected people don't gave any problems.

In our study (892 patients in General practice with diarrheoa longer
than one week) we found 14,5 % giardia infections and 8% Dientamoeba
fragilis (iron haematox kinyoun stained smears in SAF and GSA-65
tests). we are now analysing the anamnestic data (daycare centre
visits, pet owners, social economics status, countries of holidays
etc). The incidence of giardiasis in this group is much higher than
expected, but we haven't the faintest idea whether the importance of
Giardia lamblia has increased in the last 10 or 20 years in the

Joost Zaat
EMGO Institute Vrije Universiteit, Amsterdam

(jzaat at pi.net)

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