Digestive Diseases and Sciences, Vol. 30, No. 3 (March 1985), pp. 215-218 Giardiasis as a Chronic Disease ALEXANDER C. CHESTER, MD, FRANK G. MACMURRAY, MD, MARY D. RESTIFO, MD, and OSCAR MANN, MD In an effort to better describe the incidence and characteristics of chronic giardiasis in an urban private practice outpatient setting, we reviewed our experience of 65 cases. In the entire group, the mean duration of symptoms was 1.9 years. A history of foreign travel was described by 45%. No association with homosexuarty was noted. Chronic giardiasis, defined as that population symptomatic for six months or longer, constituted 58% of the entire group (38 cases). For these patients the mean duration of symptoms was 3.3 years. When compared to acute giardiasis, an increased frequency of constipation and upper gastrointestinal complaints was noted in the chronic population. Symptomatic cure was obtained in 71% of chronic cases and 93% of acute. Palliative results were noted in 18% of chronic cases and 4% of acute. We conclude that giardiasis is frequently a chronic disease in our population with symptoms lasting years. The incidence is similar in both Sexes and a history of foreign travel is often absent. A disproportionate incidence in male homosexuals was not noted in our study. Giardiasis is generally described as an acute diar- rheal illness lasting approximately six weeks and characterized by spontaneous recovery (1). Until a number of well-documented waterborne outbreaks in the United States were reported, giardiasis was usually considered a "travelers diarrhea." Recent- ly, reports suggest a high prevalence in the homo- sexual population (2-4). However, in the general population the incidence and natural history of the disease is not well described. Although chronic giardiasis is documented, re- views describe it as rare (5). In our experience chronic giardiasis is not rare nor is it in any way limited to any particular population. MATERIALS AND METHODS The study population consisted of 65 patients with giardiasis diagnosed by stool specimen examination. The Manuscript received September 9, 1983; revised manuscript received August 7, 1984; accepted October 11, 1984. From the Georgetown University Hospital, Department of Medicine, Washington, D.C. Presented in part at the 46th Annual Convention of the AmeriCan College of Gastroenterology. Address for reprint requests: Dr. Alexander C. Chester, 3301 New Mexico Avenue, N.W., Suite 348, Washington, D.C. 20016. patients were from our practice of internal medicine located in Washington, D.C. During the study period of 2V2 years, a total of 99 patients were found to have giardiasis; the study was limited to 65 available for interview. The study population is drawn from the group practice of five general internists with an active patient population of approximately 15,500. Stool specimens were obtained on patients with symptoms suggestive of an intestinal parasitic disorder. During the 2 Vz-years, the specimens of 412 patients were analyzed, with 99 demonstrating Giar- dia on at least one stool examination. A retrospective study was obtained on the 65 patients available for interview. These patients had been followed by their doctor for an average of 5.8 years and were consequently generally well-known to him. Stool specimens were obtained on each of three succes- sive days and refrigerated without preservative. The specimens were studied for cysts by microscopic exami- nation of a direct smear of the stool as well as examina- tion of the supernatant using the zinc sulfate flotation method, with and without iodine stain (6). Each specimen was examined until parasites were demonstrated or for a total of 20 min. To document parasitic cure or substanti- ate a persistent infection, three stool specimens were obtained after treatment. In cases where a second course of treatment was planned due to an inadequate clinical response to the first, stool specimens were obtained after the first and second course of treatment. The interview was conducted on the average of five months after treatment. Chronic giardiasis cases were Digestive Diseases and Sciences, Vol. 30, No. 3 (March 1985) 0163-2116/85/0300-0215504.50/0 9 1985 Plenum Publishing Corporation 215