Paragonimiasis is a foodborne zoonotic parasitic infection caused by lung flukes belonging to the genus Paragonimus. While several species can infect humans, Paragonimus uterobilateralis and Paragonimus africanus are the primary species responsible for cases across West and Central Africa, including Nigeria. The adult trematodes typically reside in the parenchyma of the lungs, where they form fibrous cysts and induce chronic inflammatory responses. Humans acquire the infection by consuming raw or undercooked freshwater crustaceans, such as crabs and crayfish, that harbor the infective metacercariae.
The complex life cycle of the Paragonimus parasite involves two intermediate hosts before reaching the definitive mammalian host.
In Nigeria, paragonimiasis is heavily focalized in regions where culinary habits involve consuming raw, improperly cooked, or pickled freshwater crabs and crayfish. Cultural practices regarding food preparation play a massive role in transmission. For instance, traditional dishes seasoned with raw or crushed freshwater crabs can harbor viable metacercariae. Furthermore, children playing in streams and rural populations engaging in artisanal crab harvesting face higher occupational and environmental exposure risks.
As juvenile flukes migrate through tissues, they cause mechanical damage, localized hemorrhage, and eosinophilic infiltration. Once settled in the pulmonary parenchyma, the host forms a fibrous capsule around the parasite, creating cystic lesions that often rupture into bronchi.
A thorough nursing assessment includes gathering a detailed dietary history regarding the consumption of freshwater crabs, alongside evaluating respiratory symptoms like chronic cough and hemoptysis. Diagnostic confirmation relies heavily on laboratory and imaging investigations:
Pharmacological intervention successfully cures paragonimiasis with minimal side effects. Praziquantel is a widely utilized first-line anthelminthic agent that disrupts the parasite's calcium homeostasis, causing paralysis and death of the fluke. Alternatively, triclabendazole serves as another highly effective treatment option, often requiring fewer doses. Nurses play a critical role in monitoring patients for adverse drug reactions, ensuring medication adherence, and managing relief interventions for residual cough or chest discomfort.
If left untreated, pulmonary paragonimiasis can lead to severe structural lung damage, including bronchiectasis, lung abscesses, pneumothorax, and chronic pleural thickening. Although pulmonary forms generally carry a favorable prognosis following proper anthelminthic therapy, ectopic infections carry higher risks. Cerebral paragonimiasis can result in permanent neurological deficits, visual disturbances, or life-threatening intracranial pressure if larval migration causes extensive localized tissue destruction.
Preventing paragonimiasis requires coordinated public health education and community engagement. Nurses working in endemic Nigerian communities must promote safe food preparation habits, emphasizing that freshwater crabs and crayfish must be thoroughly cooked, boiled, or fried before consumption. Health campaigns should also discourage practices like marinating raw crabs in lime juice or brine, which fails to kill metacercariae. Additionally, improving environmental sanitation and preventing human waste contamination of freshwater bodies help interrupt the parasite's transmission cycle.