Paragonimus heterotremus infection in Nagaland: A new focus of paragonimiasis in India

Purpose: To determine the prevalence of paragonimiasis among the patients who were attending the tuberculosis (TB) clinics at the Community Health Centre, Pfutsero, Phek District, Nagaland. To determine the species of Paragonimus that cause infection in humans and the crustacean host that acts as the infectious source for humans. Materials and Methods: Sputum specimens were examined microscopically for Paragonimus eggs and acid fast bacilli. Blood samples were tested by microenzyme-linked immunosorbant assay for Paragonimus-specific immunoglobulin G antibodies. Crab extracts prepared by digestion with artificial gastric juice were examined for Paragonimus metacercariae under a stereoscopic microscope. The species identification of the parasite was based on morphological and molecular characterizations of eggs and metacercariae employing polymerase chain reaction and DNA sequencing. Results: Seven out of the 14 patients tested seropositive for paragonimiasis and Paragonimus eggs were detected in sputum of two out of the seven seropositive patients, indicating a prevalence of 50 and an egg detection rate of 14, respectively. The prevalence was highest in the 10-30 year age group. More males got the infection than females, the ratio being 5:2. P. heterotremus was identified as the causative agent of human paragonimiasis and Potamiscus manipurensis as the crab host. Conclusions: The study revealed that paragonimiasis has been endemic in Pfutsero, Nagaland, and half of the patients attending the TB clinic were actually suffering from pulmonary paragonimiasis. This is the first confirmed report of an endemic focus of paragonimasis and description of P. heterotremus as the causative agent in Nagaland, India.