A Review of Rat Lungworm Infection and Recent Data on Its Definitive Hosts in Hawaii

Abstract

Rat lungworm (Angiostrongylus cantonensis) is a zoonotic nematode that causes rat lungworm disease (angiostrongyliasis), a potentially debilitating form of meningitis, in humans worldwide. The definitive hosts for rat lungworm are primarily members of the genus Rattus, with gastropods as intermediate hosts. This parasite has emerged as an important public health concern in the United States, especially in Hawaii, where the number of human cases has increased in the last decade. Here we discuss the current knowledge of the rat lungworm, including information on the life cycle and host species, as well as updates on known infection levels. Three species of rats have been unintentionally introduced and become established in Hawaii (Rattus exulans, R. norvegicus, and R. rattus), all of which have been documented as definitive hosts of rat lungworm. Our recent findings indicate that infection levels in rats can vary by species and age. Based on these findings, we also suggest the possibility that R. rattus populations in Hawaii are capable of developing some form of acquired immunity to infection over time, which could have important management implications related to control operations. Information on rat lungworm infection levels and distribution in Hawaii is lacking, especially in rat definitive hosts, and the U.S. Department of Agriculture (USDA) National Wildlife Research Center and the University of Hawaii at Hilo are continuing efforts to help fill these gaps in knowledge.

Keywords

• acquired immunity
• angiostrongylus cantonensis
• disease
• hawaii
• prevalence
• rat
• rattus