Current status of the treatment of paragonimiasis

Abstract

Paragonimiasis, a foodborne trematodiasis is caused by various Paragonimus species endemic in Asia, Africa, and the Americas. Human infection occurs through consuming improperly cooked freshwater crustaceans, crabs or crayfish, eating raw meat of paratenic hosts or by ingesting metacercariae from contaminated hands and cooking utensils. More than 292 million persons worldwide are at risk. The morbidity associated with paragonimiasis includes acute febrile illness and chronic pleuro-pulmonary manifestations which may be confounded with tuberculosis or lung cancer. Ectopic manifestations mostly involve the central nervous system, heart, or subcutaneous tissues. Objectives: to evaluate the efficacy and safety of currently available drugs praziquantel (PZQ) and triclabendazole (TCZ). Methods: a PubMed and Google Scholar search and reference selection was performed according to the the Preferred Reporting Items for Systematic Reviews protocol using a combination of the terms “paragonimiasis” AND “treatment” OR “therap*” from 01/2000 to 02/2022. Results: no randomized controlled trials were identified. Five open trials on 487 patients treated with PZQ showed 81%-100% parasite clearance depending on dosage and duration. Three open trials on 226 patients with TCZ showed a 99.6% efficacy. A quantitative comparison was not applicable to retrospective analyses of hospital records, case series and case reports because of surgical interventions, various co-morbidities and -medications and definitions of cure. Some patients treated with PZQ required multiple courses or re-treatment with TCZ, whereas one patient treated with TCZ required re-treatment with PZQ. Conclusions: PZQ and TCZ are usually effective for treating paragonimiasis. Controlled randomized trials are required to compare the safety, efficacy and applicability of PZQ versus TCZ and to evaluate combined PZQ-TCZ therapy.

Case Report: Reemerging Paragonimiasis in Umphang District, Thailand

“…3,9,14 This demonstrated the high efficacy of anthelmintic drugs toward treating paragonimiasis in Thai adults and children, 5,18 with no eggs detected in 2-month follow-ups. 1 This efficacy also highlights that the problem lies, not in treatment, but in misdiagnosis. In China, 69% to 89% of paragonimiasis cases were misdiagnosed between 2009 and 2019, 3,13,14,20 as is often the case for early stages of infection (asymptomatic presentations or nonspecific symptoms).…”

“…This delays effective treatment and increases the risk of morbidities, debilitation, and life-threatening complications. [1][2][3]15 Many of our patients had their treatment delayed (1 month-1 year) as a result of misdiagnoses, allowing their condition to become severe (cases 1-3) or chronic (cases 2 and 5). Lack of awareness and access to medical care (i.e., low economic status or difficulty traveling) exacerbated this delay further.…”

“…Extrapulmonary paragonimiasis develops when these immature flukes migrate to ectopic sites, including the central nervous system, pericardium, bone marrow, abdominal organs, reproductive organs, and more. 1,2,15,16 Sputum, stool, or biopsies can determine the presence of Paragonimus eggs and distinguish paragonimiasis from other pulmonary diseases of similar presentation (e.g., tuberculosis [TB], cancer, pneumonia, bronchitis, or parapneumonic effusion). 4,5,13,17 As paragonimiasis remains a neglected tropical disease according to the WHO, 18 we sought to review the clinical manifestations, predisposing factors, and treatment of six cases identified in 2017 within the Karan hill-tribe near the Thai-Myanmar border in Umphang District, Tak Province, western Thailand.…”

“…More than 293.8 million people worldwide are at risk of contracting paragonimiasis, 1 , 2 a food-born zoonotic parasitosis of the tropics and subtropics caused by Paragonimus spp. 3 – 7 Both infective metacercarial stages of Paragonimus westermani and Paragonimus heterotremus are endemic to Thailand, the latter being the main reemerging etiological agent in humans.…”

“… 3 – 5 , 8 , 9 Infection occurs through consumption of raw, pickled, salted, or cured crustaceans (secondary intermediate hosts) or mammals (paratenic hosts) that harbor live metacercaria. 1 , 3 , 4 , 9 – 14 Paragonimiasis presents initially as an acute febrile illness (e.g., fever, malaise, weight-loss, coughing) that progresses into pleuropulmonary morbidities (e.g., hemoptysis, pleural effusion, pneumothorax, peripheral eosinophilia), particularly of the lower respiratory tract. Extrapulmonary paragonimiasis develops when these immature flukes migrate to ectopic sites, including the central nervous system, pericardium, bone marrow, abdominal organs, reproductive organs, and more.…”