Co-occurrence of Angiostrongylus malaysiensis and Angiostrongylus cantonensis DNA in cerebrospinal fluid: Evidence from human eosinophilic meningitis after ingestion of raw snail dish in Thailand

Angiostrongylus cantonensis, the main causative agent of human neuroangiostrongyliasis, is a food-borne parasitic zoonosis, particularly in Southeast Asia and Mainland China. Angiostrongylus malaysiensis, a cryptic species, has not been unequivocally identified as a causative agent for human angiostrongyliasis. Here, we investigated a local incidence of human angiostrongyliasis in Kalasin Province, northeastern part of Thailand. Field and laboratory investigations, clinical symptoms, and treatment of the disease are also discussed. Five sera and three cerebrospinal fluid samples were taken from each patient who displayed clinical symptoms of mild or severe headache without neck stiffness after ingesting a local dish containing Pila virescens. With molecular evidence using PCR and DNA sequencing approaches, we confirmed the presence of A. malaysiensis and A. cantonensis DNA in the patient samples. In addition, P. virescens and Pomacea canaliculata collected in the vicinity were also examined for the existence of angistrongylid larvae. The rate of infection in the snail population was 33.3% (18 infection out of 54 examined), with A. cantonensis as the predominant species. Notably, two snails were found to be co-infected with both A. malaysiensis and A. cantonensis. This discovery comes after several years of suspicion that it could be a zoonotic pathogen. Therefore, our findings are important for public health and clinical diagnosis since clinicians are not aware of the zoonotic potential of A. malaysiensis in humans.