Emerging Human Fascioliasis: A Retrospective Study of Epidemiological Findings in Dali, Yunnan Province, China (2012-2021).

BACKGROUND Human fascioliasis is an emerging zoonotic disease caused by the trematodes, or flatworms, Fasciola hepatica and Fasciola gigantica, also known as liver flukes. This retrospective study aimed to report the epidemiological findings in 95 cases of human fascioliasis in Dali, Yunnan Province, southwestern China, diagnosed between 2012 and 2021. MATERIAL AND METHODS The epidemiologic and clinical data of 95 patients diagnosed with human fascioliasis in Dali area from January 2012 to December 2021 were collected and retrospectively analyzed. The diagnosis of fascioliasis was based on the Chinese National Standard of Diagnosis of Fascioliasis (WS/T566-2017). RESULTS The mean age of patients was 38.54±15.68 years, and there were more female patients than male (61.05% vs 38.95%). The high-incidence seasons were identified as summer and autumn. The patients with human fascioliasis lived in pastoral areas or were infected F. gigantica by consuming contaminated vegetables or water containing metacercaria. Meanwhile, human fascioliasis was diagnosed by positive serologic tests (1: 640), and Fasciola eggs (144-180×73-96 µm) were detected in stool samples of 6 patients. The most common clinical features were abdominal pain (70.53%), accompanied by elevated eosinophils in 89.5% of these patients. Antiparasitic treatment with triclabendazole at 10 mg/kg/day for 2 days led to symptom relief in all patients. CONCLUSIONS The findings from this observational epidemiological study have highlighted the importance of recognizing, diagnosing, and managing fascioliasis, which is an emerging zoonosis associated with increased human proximity to plant-eating domestic and farmed animals.

An Outbreak of Human Fascioliasis gigantica in Southwest China.

Fascioliasis is a common parasitic disease in livestock in China. However, human fascioliasis is rarely reported in the country. Here we describe an outbreak of human fascioliasis in Yunnan province. We reviewed the complete clinical records of 29 patients and performed an epidemiological investigation on the general human population and animals in the outbreak locality. Our findings support an outbreak due to Fasciola gigantica with a peak in late November, 2011. The most common symptoms were remittent fever, epigastric tenderness, and hepatalgia. Eosinophilia and tunnel-like lesions in ultrasound imaging in the liver were also commonly seen. Significant improvement of patients' condition was achieved by administration of triclabendazole®. Fasciola spp. were discovered in local cattle (28.6%) and goats (26.0%). Molecular evidence showed a coexistence of F. gigantica and F. hepatica. However, all eggs seen in humans were confirmed to be F. gigantica. Herb (Houttuynia cordata) was most likely the source of infections. Our findings indicate that human fascioliasis is a neglected disease in China. The distribution of triclabendazole®, the only efficacious drug against human fascioliasis, should be promoted.

[Clinical diagnosis and treatment in an outbreak of Fasciola gigantica infection in Yunnan Province].

OBJECTIVE: To carry out clinical diagnosis and treatment of Fasciola gigantica infection during an outbreak in Yunnan Province. METHODS: Data on epidemiology, diagnosis and treatment were collected from 27 patients. A questionnaire survey to the patients and partial villagers was carried out including history of raw food-eating and pet-raising. Animal feces were collected and examined by precipitation method and eggs incubation method. Cattle from two patients families were dissected to find Fasciola infection. Serum samples from patients, family members, and villagers were detected. Possible intermediate snails were collected from the vicinity of streams and ponds in 15 villages where patients lived. RESULTS: The earliest onset of symptoms among the patients was on March 10, 2011 and the last case was on January 10, 2012. The clinical manifestations were mainly fever with unknown reason, decreasing hemoglobin, increasing eosinophils, and hepatosplenomegaly. No parasite eggs were found in feces. Antibodies against F. gigantica were positive by ELISA in 23 patients. Fasciola eggs were then found in 4 patients' feces on February 16, 2012. F. gigantica eggs and adults were found in the hepatobiliary system of dissected cattle. Triclabendazole [10 mg/(kg x d) x2 d] was administered orally for the patients and the clinical symptoms eased. Snails including Physa acuta, Radix swinhoei and Galba pervia were collected and cercariae were found in only one snail. CONCLUSION: An outbreak of F. gigantica infection has been confirmed and the diagnosed cases effectively treated with triclabendazole.