Pleuropulmonary paragonimiasis due to Paragonimus heterotremus: molecular diagnosis, prevalence of infection and clinicoradiological features in an endemic area of northeastern India

In the northeastern region of India, paragonimiasis is emerging as an important public health problem. However, until now the identity of the species causing human infection has been uncertain and there has been little information on the prevalence and clinicoradiological features of infection in the community. Parasitological and immunological surveys revealed that paragonimiasis was hyperendemic in parts of Arunachal Pradesh. Egg positivity in the sputum was 20.9% and 4.1% in children (age ≤15 years) and adults (age >15 years), respectively. Antibody positivity against excretory-secretory antigen of the adult worm in children and adults was 51.7% and 18.7%, respectively. Chronic cough (97.2%) and haemoptysis (83.3%) were common respiratory symptoms among egg-positive cases. Chest radiography (n = 68) images from egg-positive cases showed that air space consolidation (75%), cavitary lesions (14.7%) and mediastinal adenopathy (11.8%) were very frequent. Less frequent findings were nodular lesions, bronchiectasis, mediastinal adenopathy, pleural thickening and pleural effusion. DNA extracted from eggs from the sputum of patients from Arunachal Pradesh was sequenced. Analyses of the second internal transcribed spacer (ITS2) of nuclear rDNA revealed that the species responsible is Paragonimus heterotremus.