Prevalence of recurring symptoms after infection with Giardia lamblia in a non-endemic area

Figures & data

Table I.  Inclusion criteria for the clinical diagnosis of giardiasis.

Inclusion criteria
One or more of the following:
Two or more of the following symptoms for more than one week: diarrhoea, nausea, distension, abdominal pain, foul-smelling flatulence/belching* Positive faecal test for Giardia lamblia (microscopy and/or antigen detection) The responsible doctor stating that the patient has giardiasis, either in the text or by giving the diagnosis

Note: *Based on a clinical case definition [12].

Table II.  Age and gender distribution of the total patient population and the giardia patient population at the two general practices.

	Total patient population		Giardia patient population
	n	%	n	%	p-value*
Age
0–9	835	11.8	3	2.5	<0.01
10–19	631	8.9	6	5.0	0.14
20–29	1525	21.5	41	34.5	<0.01
30–39	1412	19.9	32	26.9	0.05
40–49	834	11.7	11	9.2	0.39
50–59	671	9.4	14	11.8	0.38
60–69	474	6.7	2	1.7	0.03
70–79	308	4.3	5	4.2	0.94
80–89	312	4.4	3	2.5	0.31
90 +	100	1.4	2	1.7	0.80
Total	7102	100.0	119	100.0
Gender
Female	3951	55.5	83	69.7	<0.01
Male	3171	44.5	36	30.3
Total	7122	100.0	119	100.0

Note: *P-value results from chi-squared tests for each age group comparing the giardia patient population with the rest of the population.

Figure 1.  Development of outbreak week by week autumn 2004 and winter 2005. Note: Outbreak recognized beginning of week 45 as indicated by vertical line.

Table III.  Characteristics of patients with and without positive stool sample during an outbreak of giardiasis.

	Positive stool sample (n = 66)	No positive stool sample (n = 53)	p-value
Mean age (yrs)	33.8	41.2	0.032^*
Female/male ratio	2.67	1.95	0.43^*
Previous complaints,% (n)	13.6 (9)	11.3 (6)	0.71^*
Recurrence%, (n)	41.9 (26/62)	25.0 (6/24)	0.15^*
Treatment,% (n)	97.0 (64)	47.2 (25)	< 0.001^*
Contact before week 45,% (n)	39.4 (26)	32.7 (17)	0.45^*
Mean interval from symptoms until stool analysis (weeks)	4.9	5.6	0.30^**

Notes: *P-value computed by chi-squared test from 2 x 2 table. **P-value computed by Student's t-test for independent samples.

Table IV.  Characteristics of patients with recurring symptoms after treatment for giardiasis.

	Recurrence of symptoms (n = 32)	No recurrence of symptoms (n = 54)	p-value
Mean age (yrs)	35.3	39.8	0.23^**
Female/male ratio	1.67	2.38	0.45^*
Previous complaints,% (n)	25.0 (8)	5.6 (3)	0.009^*
Positive faecal test,% (n)	81.3 (26)	66.7 (36)	0.15^*
Mean treatment dose (g)	7.8	7.8	0.89^**
Mean treatment duration (days)	6.8	6.8	0.83^**
Mean interval from symptoms until treatment (weeks)	5.6	5.8	0.69^**
Mean interval from symptoms until stool analysis (weeks)	4.8	5.1	0.63^**

Notes: *P-value computed by chi-squared test from 2 x 2 table. **P-value computed by Student's t-test for independent samples. Full data for three patients receiving treatment are missing.