Establishing seasonal and alert influenza thresholds in Cambodia using the WHO method: implications for effective utilization of influenza surveillance in the tropics and subtropics

Objective: To establish seasonal and alert thresholds and transmission intensity categories for influenza to provide timely triggers for preventive measures or upscaling control measures in Cambodia. Methods: Using Cambodia’s influenza-like illness (ILI) and laboratory-confirmed influenza surveillance data from 2009 to 2015, three parameters were assessed to monitor influenza activity: the proportion of ILI patients among all outpatients, proportion of ILI samples positive for influenza and the product of the two. With these parameters, four threshold levels (seasonal, moderate, high and alert) were established and transmission intensity was categorized based on a World Health Organization alignment method. Parameters were compared against their respective thresholds. Results: Distinct seasonality was observed using the two parameters that incorporated laboratory data. Thresholds established using the composite parameter, combining syndromic and laboratory data, had the least number of false alarms in declaring season onset and were most useful in monitoring intensity. Unlike in temperate regions, the syndromic parameter was less useful in monitoring influenza activity or for setting thresholds. Conclusion: Influenza thresholds based on appropriate parameters have the potential to provide timely triggers for public health measures in a tropical country where monitoring and assessing influenza activity has been challenging. Based on these findings, the Ministry of Health plans to raise general awareness regarding influenza among the medical community and the general public. Our findings have important implications for countries in the tropics/subtropics and in resource-limited settings, and categorized transmission intensity can be used to assess severity of potential pandemic influenza as well as seasonal influenza.

Leptospirosis in Takeo Province, Kingdom of Cambodia, 2003.

BACKGROUND: In Cambodia, epidemiology and disease burden of leptospirosis were not addressed as they do not have an existing surveillance system and have limitations on their laboratory diagnosis. OBJECTIVE: Define the existence of leptospirosis and determine the antibodies to serovars of leptospires in Cambodia. MATERIAL AND METHOD: One hundred and twenty-one suspected cases of leptospirosis were enrolled in this cross-sectional study, between September 8 and November 30, 2003 from Takeo Provincial Hospital in Doun Keo District, Cambodia. RESULTS: Common clinical manifestations were fever (96%), headache (92%), and myalgia (87%). Common risk behaviors were throwing garbage on the ground (84%), pulling out sprouts (77%), fertilizing (49%), and plowing (47%). Microscopic agglutination test result confirmed four cases and polymerase chain reaction test result confirmed seven cases. Two cases each showed antibodies to serovars Javanica and Australis. An estimated annual incidence of leptospirosis in Takeo province was 7.65 per 100,000 populations. Further studies to define epidemiology and burden of disease are needed. CONCLUSION: Increasing awareness and knowledge on leptospirosis among people are necessary to decrease the impact of leptospirosis in Cambodia.