Human cystic echinococcosis in a Uruguayan community: a sonographic, serologic, and epidemiologic study.

Abstract

Abstract. A prevalence and transmission study of human cystic echinococcosis (CE), due to infection with the dog tapeworm Echinococcus granulosus, was undertaken in the village of La Paloma in central Uruguay. The human population was registered and screened for CE by abdominal ultrasound scan as well as a number of serologic tests. Dogs were screened for E. granulosus infection by arecoline purgation as well as specific coproantigen testing. The total prevalence of human CE (new cases and those with a previous history) was 5.6% (64 of 1,149); 3.6% (40) of the cases were new ultrasound detected asymptomatic cases (mean age ϭ 45 years). Age prevalence increased from 1.1% in the 4-6-year-old group to Ͼ 11% in the Ͼ 60-year-old group; the 20-29-year-old group had a significantly higher CE rate of 7.4%, compared with younger and older age groups, and there was no difference between sexes. A CE rate of 3.9% (20 of 514) was also recorded by ultrasound for new cases in the population residing outside the village. Most of the hydatid cysts were located in the liver presenting as either univesicular cysts or a solid mass, and of those 71% and 63%, respectively, with such cyst presentations were seropositive against E. granulosus cyst fluid antigens. Two of eight individuals who were filter paper blood spot seropositive, but ultrasound scan negative, were subsequently diagnosed respectively with pulmonary hydatidosis after radiography, and hepatic hydatidosis after computed tomography scan. Of 36 households with a CE patient, 32 were single cases while four households each harbored two CE cases. This did not represent a clustered distribution within families (23 of 117). Almost 20% of the dogs from La Paloma were found infected with E. granulosus after purge examination, with a mean worm number of 67 (range ϭ 1-1,020). An additional eight dogs that were purge negative were Echinococcus coproantigen positive. The study showed that human CE is highly endemic in Uruguay, with one of the highest local prevalence rates in the world. Transmission appears to occur readily within well-developed towns, as well as on rural sheep ranches. Mass screening by ultrasound scanning with confirmatory serologic testing is an effective approach to case detection at the community level.Echinococcosis (CE) is a chronic zoonotic parasitic helminthic disease due to infection with the larval stage (hydatid) of the small dog tapeworm Echinococcus granulosus. The parasite has a global distribution but is particularly prevalent in rural areas where it is transmitted in a cycle between the dog, the definitive host, and the sheep, the intermediate host. 1 In South America, E. granulosus is endemic and a significant public health problem in several countries including Brazil, Peru, Bolivia, Chile, Argentina, and Uruguay. [2][3][4][5][6][7][8][9][10][11][12]

Serological Diagnosis of Lung Cystic Hydatid Disease Using the Synthetic p176 Peptide

“…In the bivariate analysis, seropositivity for p176 was associated with having more than one cyst. The association between numbers of cysts and seroprevalence was previously described by Dueger et al, who used Western blotting in a study performed with naturally infected sheep (9), and by Cohen et al, who used ELISA in a study performed with humans (6). In this case series, the significance of the bivariate associations of serology with numbers of cysts and organ involvement did not persist upon multivariate analysis.…”

An extensive ultrasound and serologic study to investigate the prevalence of human cystic echinococcosis in northern Libya.

“…Human CE prevalence rates varied between 0.4% and 3.6% in Tunisia, 3,34 up to 5.6% in Kenya, 24,35 0.3-2.9% in China, 36,37 1.3-5.6% in Uruguay, 33,38 and up to 8.6% in Argentina. 39 However, the current study is probably one of the largest human CE mass screening programs undertaken.…”

“…The 303 hepatic hydatid cysts detected by ultrasound during the survey were classified according to image appearance as described previously. 28,33 However, a slight modification was included based on clinical grounds that involved division of Type III cystic images into two subgroups (IIIa and IIIb), and creation of an additional group, i.e., Type VI, which related to multiple cysts.…”

Biological, Epidemiological, and Clinical Aspects of Echinococcosis, a Zoonosis of Increasing Concern

“…Similar observations were made in other areas of endemic infection (168). In most of the larger series of patients, there were no significant differences in the gender ratios of individuals with CE (25,149,151).…”

“…This technique is well accepted by the population, explores abdominal sites, identifies cyst types, and can be performed at relatively low cost (25,149,151,185). Differential diagnosis of other space-occupying lesions (tumors, liver abscesses, etc.)…”