Clinical Observations in Patients With Cystic Fibrosis-Related Diabetes and Self-Reported Ototoxicity Symptoms.

PURPOSE: Persons with cystic fibrosis (PwCF) are at high risk for ototoxicity due to the routine use of intravenous aminoglycoside (IV-AG) antibiotics in respiratory infection management. Additionally, factors that contribute to ototoxicity-related symptom development and severity in PwCF are unknown. Given the increased risk of ototoxicity in people with diabetes, we explored the association between cystic fibrosis-related diabetes (CFRD) and self-reported ototoxicity symptoms (tinnitus and vestibular problems) in PwCF treated with aminoglycosides. METHOD: PwCF (N = 39; 25 females, 14 males; Mage = 30.1 years, SD = 10.3) were recruited from the Cystic Fibrosis Care Center at Oregon Health & Science University. Patients completed the validated questionnaires to ascertain their experiences with ototoxicity-related symptoms of tinnitus and balance function. The diagnosis of CFRD, including oral glucose tolerance testing (OGTT), insulin treatment, hemoglobin A1c, and cumulative IV-AG treatment history, was obtained through a medical chart review. Participants were classified into three groups based on their medical diagnoses via OGTT: normal glucose tolerance (NGT; control; n = 16), abnormal glucose tolerance (AGT; n = 9), and CFRD (n = 14). Participants in each group were further classified based on survey outcomes for ototoxicity-related symptoms. RESULTS: There was a trend toward a higher proportion of patients with CFRD reporting tinnitus compared to the AGT and NGT groups, but did not meet statistical significance (X2 = 2.24, p = .13). Approximately, 43% of patients with CFRD reported experiencing clinically significant tinnitus lasting > 3 min compared to 11% in the AGT group and 13% in the NGT group (X2 = 3.751, p = .05). Cumulative IV-AG exposure tended to be higher in CFRD compared to other groups. High balance function was generally reported in all groups. CONCLUSIONS: Patients with CFRD have greater ototoxicity-related symptoms. Further investigation of the relationship between CF-related comorbidities and the risk of developing ototoxicity-related symptoms is warranted to improve the detection and management of ototoxicity in PwCF.

Host snail species exhibit differential Angiostrongylus cantonensis prevalence and infection intensity across an environmental gradient.

Diverse snail species serve as intermediate hosts of the parasitic nematode Angiostrongylus cantonensis, the etiological agent of human neuroangiostrongyliasis. However, levels of A. cantonensis infection prevalence and intensity vary dramatically among these host species. Factors contributing to this variation are largely unknown. Environmental factors, such as precipitation and temperature, have been correlated with overall A. cantonensis infection levels in a locale, but the influence of environment on infection in individual snail species has not been addressed. We identified levels of A. cantonensis prevalence and intensity in 16 species of snails collected from 29 sites along an environmental gradient on the island of Oahu, Hawaii. The relationship between infection levels of individual species and their environment was evaluated using AIC model selection of Generalized Linear Mixed Models incorporating precipitation, temperature, and vegetation cover at each collection site. Our results indicate that different mechanisms drive parasite prevalence and intensity in the intermediate hosts. Overall, snails from rainy, cool, green sites had higher infection levels than snails from dry, hot sites with less green vegetation. Intensity increased at the same rate along the environmental gradient in all species, though at different levels, while the relation between prevalence and environmental variables depended on species. These results have implications for zoonotic transmission, as human infection is a function of infection in the intermediate hosts, ingestion of which is the main pathway of transmission. The probability of human infection is greater in locations with higher rainfall, lower temperature and more vegetation cover because of higher infection prevalence in the gastropod hosts, but this depends on the host species. Moreover, severity of neuroangiostrongyliasis symptoms is likely to be greater in locations with higher rainfall, lower temperature, and more vegetation because of the higher numbers of infectious larvae (infection intensity) in all infected snail species. This study highlights the variation of infection prevalence and intensity in individual gastropod species, the individualistic nature of interactions between host species and their environment, and the implications for human neuroangiostrongyliasis in different environments.

Species Identity and Size are Associated with Rat Lungworm Infection in Gastropods.

Angiostrongylus cantonensis, the rat lungworm, is an emerging zoonotic pathogen that cycles between definitive rat and intermediate gastropod hosts. Zoonotic infection occurs when humans intentionally or accidentally consume infectious larvae in a gastropod host, and may manifest as neuroangiostrongyliasis, characterized by eosinophilic meningitis, severe neurological impairment, and even death. Thus, the risk of A. cantonensis zoonoses may be related to the distribution of A. cantonensis larvae across gastropod hosts. We screened 16 gastropod species from 14 communities on the island of O'ahu, Hawai'i, USA, to characterize the distribution of A. cantonensis among species and across host size. Prevalence (proportion of the population infected) and infection intensity (density of worms in host tissue) varied among gastropod species. Prevalence also varied with gastropod host size, but this relationship differed among host species. Most host species showed a positive increase in the probability of infection with host size, suggesting that within species relatively larger hosts had higher prevalence. The density of worms in an infected snail was unrelated to host size. These results suggest that variation in A. cantonensis infection is associated with demographic structure and composition of gastropod communities, which could underlie heterogeneity in the risk of human angiostrongyliasis across landscapes.