Pedro L. Moro

Field diagnosis of Echinococcus granulosus infection among intermediate and definitive hosts in an endemic focus of human cystic echinococcosis

Human, canine and ovine echinococcosis prevalence was determined in a highland community located in the central Peruvian Andes during 1997 and 1998. Human echinococcosis was determined using portable ultrasonography, chest X-ray examination, and an enzyme-linked immunoelectrotransfer blot (EITB) assay. Canine echinococcosis was determined using microscopy stool examinations and a coproantigen detection enzyme-immunoassay (EIA) for Echinococcus granulosus. Ovine echinococcosis was determined by an EITB assay for sheep echinococcosis and necropsy examination of viscera from domestic slaughtered animals. An abdominal ultrasound, a chest X-ray examination and an EITB for echinococcosis were performed on 214 subjects (45% of the village population). The frequency of presumptive liver/abdominal, lung and liver-lung hydatid cysts was 5.1% (11/214), 3.7% (8/214) and 0.5% (1/214), respectively. The overall prevalence of human cystic echinococcosis was 9.3% (20/214). The frequency of canine echinococcosis was 46% (23/50) and 32% (16/50) by the coproantigen EIA test and arecoline purging, respectively. The frequency of sheep echinococcosis was 65% (22/34) by the EITB and 38% (13/34) by necropsy. We demonstrated a high prevalence of human and animal echinococcosis in this Peruvian village. In remote areas where echinococcosis is endemic, both the coproantigen EIA and arecoline purging may be used for the study of canine echinococcosis; the EITB is useful in establishing the diagnosis of echinococcosis in sheep prior to necropsy.

Evaluation of three enzyme-linked immunosorbent assays (ELISAs) for the detection of serum antibodies in sheep infected with Echinococcus granulosus

The aim of this study was to develop an immunological method for the identification of sheep infected with Echinococcus granulosus which would allow the monitoring of animals imported into countries free from hydatidosis and as an aid to countries where control schemes for the disease are in operation. Three enzyme-linked immunosorbent assays (ELISAs) were developed and validated, using as antigen either a purified 8 kDa hydatid cyst fluid protein (8kDaELISA), a recombinant EG95 oncosphere protein (OncELISA) or a crude protoscolex preparation (ProtELISA). Sera used for the assay validations were obtained from 249 sheep infected either naturally or experimentally with E. granulosus and from 1012 non-infected sheep. The highest diagnostic sensitivity was obtained using the ProtELISA at 62.7 and 51.4%, depending on the cut-off. Assay sensitivities were lower for the 8kDaELISA and the OncELISA. Diagnostic specificities were high, ranging from 95.8 to 99.5%, depending on the ELISA type and cut-off level chosen. A few sera from 39 sheep infected with T. hydatigena and from 19 sheep infected with T. ovis were recorded as positive. Western immunoblot analysis revealed that the dominant antigenic components in the crude protoscolex antigen preparation were macromolecules of about 70-150 kDa, most likely representing polysaccharides. This study demonstrated that the ProtELISA was the most effective immunological method of those assessed for detection of infection with E. granulosus in sheep. Because of its limited diagnostic sensitivity of about 50-60%, it should be useful for the detection of the presence of infected sheep on a flock basis and cannot be used for reliable identification of individual animals infected with E. granulosus.

Human Hydatidosis in the Central Andes of Peru: Evolution of the Disease over 3 Years

To document the natural history of Echinococcus granulosus infection and response to treatment of human hydatidosis, we reexamined 28 of 37 subjects with E. granulosus infection diagnosed in an epidemiological study conducted in 1994. Twenty-six (70%) of those 37 subjects underwent abdominal ultrasonography, chest radiography, and enzyme-linked immunoelectrotransfer blot assay in 1997. Medical records from two additional individuals were reviewed. Eight patients had their cysts surgically removed during the 3-year follow-up interval; no surgical complications or recurrences occurred. Among eight patients with cystic disease not treated by surgery, four had cyst-growth ranging from 0.4 to 1.4 cm during the 3-year interval. One patient developed a new cyst and anothers simple cyst became septate; two developed new calcifications. Of 12 seropositive subjects with no cysts present in 1994, 10 reverted to seronegative, a finding that suggests a significant proportion of seropositive subjects in echinococcus-endemic regions may have only transient infection without disease. When cysts do develop, their growth rates and time courses are highly variable; over the 3-year period, we observed growth, septation, degeneration, and calcification of cysts.

Gallstone disease in high-altitude Peruvian rural populations.

Objective: Cholelithiasis is a common problem in hospitals of the Peruvian Andes; however, its prevalence in Andean communities is unknown. To estimate the prevalence of gallstone disease in this locale, we conducted a cross-sectional community study in three high-altitude Peruvian rural villages (i.e., > 3000 m above sea level). Methods: We examined 911 volunteers > 15 yr of age from three villages for gallstone disease by history and ultrasonography. Risk factors for gallstone disease were examined in 382 volunteers from one village. Results: The age-adjusted prevalence of gallstone disease ranged from 4–10% in men and from 18–20% in women. Women had significantly higher age-adjusted prevalence rates than did men. The prevalence of gallstone disease increased significantly with age and decreased significantly with alcohol consumption. Although not statistically significant, we found a positive association between gallstone disease and body mass index. Conclusion: The results of this study indicate that gallstone disease, commonly perceived as a disease of the developed world, is also a common problem in high-altitude Peruvian communities.

Ischemic Cardiac Events during the Department of Health and Human Services Smallpox Vaccination Program, 2003

Ten ischemic cardiac events (ICEs) were reported among 37,901 initial US Department of Health and Human Services (DHHS) smallpox vaccinees. Symptoms developed a median of 10 days after vaccination (range, 0-28 days). The median age of case patients was 56 years (range, 42-65 years), and 60% were male. Seven (70%) of the case patients had >/=3 cardiac risk factors or probable coronary artery disease before vaccination. Two women, 55 and 57 years of age, experienced acute myocardial infarction and fatal cardiac arrests. Background rates of ICEs during a 3-week period for civilian populations that were age and sex matched to DHHS vaccinees were estimated. The observed number of myocardial infarctions exceeded estimated expectations (5 vs. 2) but remained within the 95% predictive interval (PI) (0.6-5.4). New onset angina was observed significantly less frequently than estimated expectations (1 vs. 10; 95% PI, 3.5-15.7). After persons with >/=3 cardiac risk factors or known heart disease were deferred from vaccination, no ICEs were reported among an additional 6638 vaccinees.

Intestinal parasites of the grey fox (Pseudalopex culpaeus) in the central Peruvian Andes

The intestines of 20 grey Peruvian foxes (Pseudalopex culpaeus) were examined for the presence of Echinococcus granulosus and other intestinal parasites. Echinococcus granulosus was not found in foxes but Taenia hydatigena and T. multiceps were found in 7 and 4 animals respectively. The grey fox may not be a suitable definitive host for E. granulosus. However, it may act as a sylvatic reservoir of T. hydatigena and T. multiceps in the central Peruvian Andes.