Abstract. The objective of this study was to 1) assess the incidence of strongyloidiasis in the United States, 2) evaluate demographic and regional associations, and 3) identify comorbid conditions as risk factors for death. A population-based case-control study was performed by using mortality data during 1991-2006. We identified 347 strongyloidiasis deaths (0.79 per 10 million deaths, 14-29 deaths per year), which decreased slightly over time. Deaths occurred primarily among older (median age = 66.0 years), white (57.6%) and Hispanic (22.2%) men (69.2%), residing in the Southeastern United States (49.3%). Associated health conditions included chronic obstructive pulmonary disease (28.7%, odds ratio [OR] = 4.0, 95% confidence interval [CI] = 3.0-5.4) and infection with human immunodeficiency virus (12.5%, OR = 4.6, 95% CI = 2.7-7.9). Strongyloidiasis deaths in the second half of the study period (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006) were less likely to be associated with chronic obstructive pulmonary disease (19.4%, OR = 1.2, 95% CI = 0.7-1.9), but continued to be associated with human immunodeficiency virus infection (12.9%, OR = 2.8, 95% CI = 1.3-6.0). Early detection and treatment of at-risk patients with latent strongyloidiasis infections is needed to reduce strongyloidiasis mortality.

Statewide hospital discharge data were used to assess the economic burden of neurocysticercosis in Los Angeles County (LAC) from 1991 through 2008. A neurocysticercosis hospitalization was defined as having a discharge diagnosis of cysticercosis in addition to convulsions, seizures, hydrocephalus, cerebral edema or cerebral cysts. This study identified 3,937 neurocysticercosis hospitalizations, with the number of annual hospitalizations remaining relatively unchanged over the study period (R2 = 0.01), averaging 219 per year (range 180–264). The total of all neurocysticercosis hospitalization charges over the study period was $136.2 million, averaging $7.9 million per year. The average charge per patient was $37.6 thousand and the most common payment method was Medicaid (43.9%), followed by private insurance (24.5%). The average length of stay was 7.2 days. The substantial number of hospitalizations and significant economic cost underscore the importance of neurocysticercosis in LAC.

To assess the burden of neurocysticercosis (NCC) in California we examined statewide hospital discharge data for 2009. There were 304 cases hospitalized with NCC identified (incidence = 0.8 per 100,000). Cases were mostly Latino (84.9%), slightly more likely to be male than female (men 57.6%, women 42.4%) with an average age of 43.5 years. A majority of cases were hospitalized in Southern California (72.1%) and many were hospitalized in Los Angeles County (44.7%). Men were more likely than women to have severe disease including hydrocephalus (29.7% vs. 18.6%, p = 0.027), resulting in longer hospitalizations (>4 days, 48.0% vs. 32.6%, p = 0.007) that were more costly (charge>$40 thousand men = 46.9% vs. woman = 4.1%, p = 0.026). Six deaths were recorded (2.0%). The total of NCC-related hospital charges exceeded $17 million; estimated hospital costs exceeded $5 million. Neurocysticercosis causes appreciable disease and exacts a considerable economic burden in California.

In 2004, Los Angeles County confirmed 11 cases of symptomatic West Nile virus (WNV) infections in children younger than 18 years of age. Eight had WNV fever, 2 had meningitis and 1 had encephalitis. Fever, rash, nausea and vomiting were the most prominent symptoms at presentation; median duration of illness was 7 days. Clinicians should be aware of the risk of WNV illness, confirm this diagnosis and report suspected WNV cases to their local health department.

Although flea-borne rickettsiosis is endemic in Los Angeles County, outbreaks are rare. In the spring of 2015 three human cases of flea-borne rickettsiosis among residents of a mobile home community (MHC) prompted an investigation. Fleas were ubiquitous in common areas due to presence of flea-infested opossums and overabundant outdoor cats and dogs. The MHC was summarily abated in June 2015, and within five months, flea control and removal of animals significantly reduced the flea population. Two additional epidemiologically-linked human cases of flea-borne rickettsiosis detected at the MHC were suspected to have occurred before control efforts began. Molecular testing of 106 individual and 85 pooled cat fleas, blood and ear tissue samples from three opossums and thirteen feral cats using PCR amplification and DNA sequencing detected rickettsial DNA in 18.8% of the fleas. Seventeen percent of these cat fleas tested positive for R. felis-specific DNA compared to under two (<2) percent for Candidatus R. senegalensis-specific DNA. In addition, serological testing of 13 cats using a group-specific IgG-ELISA detected antibodies against typhus group rickettsiae and spotted fever group rickettsiae in six (46.2%) and one (7.7%) cat, respectively. These results indicate that cats and their fleas may have played an active role in the epidemiology of the typhus group and/or spotted fever group rickettsial disease(s) in this outbreak.