Characteristics of an Acanthamoeba keratitis outbreak in British Columbia between 2003 and 2007.

OBJECTIVE: Quantify and describe Acanthamoeba keratitis (AK) cases in British Columbia (BC). DESIGN: A comparison of annual incidence rates confirms the presence of an outbreak. A case series describes characteristics of the outbreak. PARTICIPANTS: All laboratory-confirmed AK cases (persons) in BC (1988-2011; n = 68) were included in the incidence rate comparison. Of the 42 cases (persons) between 2003 and 2007, 32 were selected to interview (laboratory confirmed, 2005-2007), and the 23 who completed interviews form the case series. METHODS: A comparison of standardized annual incidence rates in historic to outbreak periods is performed by z-score test. A telephone interview and descriptive analysis detailing demographics, risk factors, and contact lens (CL) wearing habits was completed for 23 cases. MAIN OUTCOME MEASURES: We measure number of laboratory confirmed cases in BC. In addition, risk factors and potential exposures of these cases are reported. RESULTS: The annual incidence of AK increased significantly from 0.029 to 0.200 per 100 000 population between historic years (1988-2002) and outbreak years (2003-2007; P = 0.022). The annual incidence of AK has since returned to near historic levels (0.056/100 000 population). The case series identified multiple risk factors, including the use of a specific recalled solution (60.9%), daily soft CL wear (95.7%), all-in-one solutions (95.7%), showering while wearing CL (65.2%), and generally poor CL hygiene. CONCLUSIONS: A significant increase in annual AK incidence occurred between 2003 and 2007 in BC. After 2007, the incidence of AK returned to near historic levels. The recalled solution was associated with many cases; however, other risk factors were also identified, including being unaware of the recall and poor CL hygiene practices, highlighting the need for improved education about the severity of AK and consequences of improper CL hygiene. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

West Nile virus range expansion into British Columbia.

In 2009, an expansion of West Nile virus (WNV) into the Canadian province of British Columbia was detected. Two locally acquired cases of infection in humans and 3 cases of infection in horses were detected by ELISA and plaque-reduction neutralization tests. Ten positive mosquito pools were detected by reverse transcription PCR. Most WNV activity in British Columbia in 2009 occurred in the hot and dry southern Okanagan Valley. Virus establishment and amplification in this region was likely facilitated by above average nightly temperatures and a rapid accumulation of degree-days in late summer. Estimated exposure dates for humans and initial detection of WNV-positive mosquitoes occurred concurrently with a late summer increase in Culex tarsalis mosquitoes (which spread western equine encephalitis) in the southern Okanagan Valley. The conditions present during this range expansion suggest that temperature and Cx. tarsalis mosquito abundance may be limiting factors for WNV transmission in this portion of the Pacific Northwest.

A Retrospective Cohort Study of Tick Paralysis in British Columbia.

BACKGROUND: Tick paralysis is a frequently overlooked severe disease characterized by bilateral ascending flaccid paralysis caused by a neurotoxin produced by feeding ticks. We aimed to characterize suspected tick paralysis cases documented at the BC Centre for Disease Control (BCCDC) in British Columbia (BC) from 1993 to 2016 and reviewed prevention, diagnosis, and treatment considerations. METHODS: Demographic, geographic, and clinical data from test requisition forms for ticks submitted to the BCCDC Public Health Laboratory (PHL) from patients across BC between 1993 and 2016 for suspected human and animal tick paralysis were reviewed. Descriptive statistics were generated to characterize tick paralysis cases in BC, including tick species implicated, seasonality of disease, and regional differences. RESULTS: From 1993 to 2016, there were 56 cases of suspected tick paralysis with at least one tick specimen submitted for testing at the BCCDC PHL. Humans and animals were involved in 43% and 57% of cases, respectively. The majority of cases involved a Dermacentor andersoni tick (48 cases or 86%) and occurred between the months of April and June (49 cases or 88%). Among known locations of tick acquisition, the Interior region of BC was disproportionately affected, with 25 cases (69%) of tick bites occurring in that area. CONCLUSIONS: Tick paralysis is a rare condition in BC. The region of highest risk is the Interior, particularly during the spring and summer months. Increasing awareness of tick paralysis among healthcare workers and the general public is paramount to preventing morbidity and mortality from this rare disease.

Surveillance for Borrelia burgdorferi in Ixodes Ticks and Small Rodents in British Columbia.

To determine the prevalence of Borrelia burgdorferi in British Columbian ticks, fieldwork was conducted over a 2-year period. In all, 893 ticks (Ixodes pacificus, I. angustus, I. soricis, Ixodes spp., and Dermacentor andersoni) of different life stages were retrieved from 483 small rodents (Peromyscus maniculatus, Perognathus parvus, and Reithrodontomys megalotis). B. burgdorferi DNA was detected in 5 out of 359 tick pools, and 41 out of 483 mice were serologically confirmed to have antibodies against B. burgdorferi. These results were consistent with previous studies, data from passive surveillance in British Columbia, and data from neighboring states in the Pacific Northwest, suggesting a continually low prevalence of B. burgdorferi in British Columbia ticks.