Variation in Angiostrongylus cantonensis infection in definitive and intermediate hosts in Hawaii, a global hotspot of rat lungworm disease

Abstract

Angiostrongylus cantonensis (rat lungworm) is a tropical and subtropical parasitic nematode, with infections in humans causing angiostrongyliasis (rat lungworm disease), characterized by eosinophilic meningitis. Hawaii has been identified as a global hotspot of infection, with recent reports of high infection rates in humans, as well as rat definitive and snail intermediate hosts. This study investigated variation in A. cantonensis infection, both prevalence and intensity, in wild populations of two species of rats (Rattus exulans and R. rattus) and one species of snail (Parmarion martensi). An overall infection prevalence of 86.2% was observed in P. martensi and 63.8% in rats, with R. exulans (77.4%) greater than R. rattus (47.6%). We found infections to vary with environmental and host-related factors. Body mass was a strong predictor of infection in all three species, with different patterns seen between sexes and species of rats. Infection prevalence and intensity for R. exulans were high in May 2018 and again in February 2019, but generally lower and more variable during the intervening months. Information on sources of variability of infection in wild host populations will be a crucial component in predicting the effectiveness of future disease surveillance or targeted management strategies.

Older urban rats are infected with the zoonotic nematode Angiostrongylus cantonensis

“…The significance of tibia length as a predictor in our model supports the concept that older rats are more likely to have been exposed to the parasite at some point during their lifespan, possibly even multiple times ( Simões et al, 2014 ; Niebuhr et al, 2021 ). This contrasts with Jarvi et al (2017) , who reported a negative correlation between weight (another proxy for age) and adult worm burden in Hawaiian R. rattus .…”

“…Our previous work at a zoo in western Sydney (approximately 30 km west of the city of Sydney) demonstrated that 9/14 (64%) of trapped R. norvegicus were infected with A. cantonensis ( Rivory et al, 2023 ). The prevalence in the present study is considerably lower, highlighting the random variation in A. cantonensis abundance between complex host-parasite systems from one habitat to another ( Niebuhr et al, 2021 ; Rollins et al, 2021 ).…”

Angiostrongylus cantonensis and neuroangiostrongyliasis (rat lungworm disease): 2020

“…This Special Issue of Parasitology is based on cutting-edge research presented at the 6th International Workshop on Angiostrongylus and Angiostrongyliasis held in Hilo, Hawai`i, in January 2020. It provides research updates on gastropod and rat infection levels under natural conditions in multiple geographic areas (Niebuhr et al, 2021;Estano et al, 2021;Walden et al, 2021), under laboratory conditions (Hamilton et al, 2021;Wun et al, 2021a, b), as well as alternative parasite transmission pathways (Modry et al, 2021). The latest research on infection in non-human species is described (Feckova et al, 2021;Malik et al, 2021;Tsai and Chen, 2021;Wun et al, 2021a, b).…”

A systematic review of the diversity and virulence correlates of metastrongyle lungworms in marine mammals

“…Metastrongyloidea (Nematoda: Strongylida), also known as lungworms or metastrongyles, are common parasites of the respiratory, cardiovascular and rarely the auditory system of mammals (Measures, 2001 ). The definitive hosts become infected through ingestion of larval stages within invertebrate intermediate hosts or free on pasture; therefore, metastrongyle infection can be quite common among free-foraging domestic and wild mammals (Measures, 2001 ; Regassa et al ., 2010 ; Niebuhr et al ., 2021 ). Like other helminth infections, the pathogenic effects of metastrongyloidiasis can be broad with impacts that range from subclinical infection to bronchopneumonia and death (Measures, 2001 ; Forbes, 2021 ).…”