Transmission sources and severe rat lung worm diseases in travelers: a scoping review

Background Rat lung worm disease (RLWD) has several clinical forms including eosinophilic meningitis (EOM) and two severe forms, eosinophilic meningoencephalitis (EOME) and eosinophilic radiculomyelitis (EORM). It remains unclear whether transmission sources are associated with severe forms of RLWD. This study aimed to evaluate if transmission factors are related to the severity of RLWD among travelers by using a scoping review of case reports. Methods This was a review using five databases to retrieve case reports and case series of travelers with RLWD. Clinical data and transmission sources of reported cases diagnosed as RLWD were retrieved. The outcome of the study was occurrence of severe forms of RLWD defined as EOME, EORM, and combined EOME/EORM. Results We retrieved 1,326 articles from five databases and 31 articles were included in the analysis. There were 84 cases eligible from 15 countries. Four cases were excluded. Seventy cases were in EOM group and 10 cases had EOME or EORM. Compared with the EOM group, the EOME, EORM, and combination EOME/EORM group had similar age, sex, and risk factors of consumptions of apple snails, shrimp and prawn, and salad/vegetables. The EOME group had higher proportion of consumption of African snails than the EOM group (60% vs 13.8%). However, only one study reported the consumption of African snails and the heterogeneity between studies and the small sample size impeded direct comparisons between groups. Conclusions RLWD in travelers can be found in most continents and mostly get infected from endemic countries of RLWD. Further studies are required to evaluate the association between transmission vectors and severity of RLWD.