(P-PH-6) Seroprevalence of Japanese Encephalitis Virus (JEV), Murray Valley Encephalitis Virus (MVEV) and Kunjin Virus Among Blood Donors

Sunday, October 20, 2024

12:00 PM - 1:00 PM

Presenting Author(s)

Rena Hirani, PhD

Australian Red Cross Lifeblood
Sydney, New South Wales, Australia

Background/Case Studies: Japanese encephalitis virus (JEV), Murray Valley encephalitis virus (MVEV) and Kunjin virus are mosquito-borne flaviviruses transmitted to humans by the Culex mosquitoes. All three viruses can cause asymptomatic or mild infections to severe encephalitis. MVEV and Kunjin virus are endemic to Australia and Japanese encephalitis is endemic to Asia. In February 2022, JEV was detected in piggeries in the southern and eastern parts of mainland Australia for the first time. Outbreaks for MVEV and Kunjin virus have occurred periodically in Australia. This study aimed to determine the seroprevalence of JEV, MVEV and Kunjin virus using samples from Australian blood donors who donated in areas where there was higher risk of transmission compared with donors from lower risk areas where Culex mosquitoes are not detected.

Study

Design/Methods: Serum samples from all blood donors who attended 9 blood collection centres located in areas of high-risk for infection based on proximity to infected piggeries and positive cases, and 3 low-risk centres (Adelaide in South Australia and Tasmania), from 4 of the 8 Australian states and territories were collected. Samples were analysed at the Institute of Clinical Pathology and Medical Research at Westmead Hospital, Sydney using specific JEV, MVEV and Kunjin virus defined epitope blocking assays.

Results/Findings:

A total of 5,257 serum samples were collected between 8 August to 17 September 2022. The overall crude seroprevalences were 2.2% (115/5257; 95% CI 1.8–2.6) for JEV, 3.0% (156/5257; 95%CI 2.5%-3.5%) for MVEV and 5.1% (269/5257; 95%CI 4.5%-5.8%) for Kunjin Virus. Figure A indicates the number of samples that were seropositive for various virus combinations.

Seroprevalence from donor centres in high-risk areas was 2.4% (76/3232; 95% CI 1.9-2.9) for JEV, 3.5% (114/3232; 95% CI 2.9-4.2) for MVE and 5.8% (186/3232; 95% CI 5.0-6.6) for Kunjin virus.

In comparison, seroprevalence from donor centres in low-risk areas was 1.9% (39/2025; 95% CI 1.4–2.6) for JEV, 2.1% (42/2025; 95% CI 1.5-2.8) for MVE and 4.1% (83/2025; 95% CI 3.3-5.1) for Kunjin virus.

Conclusions: Recent outbreaks of endemic (MVEV and Kunjin) and previously non-endemic (JEV) flaviviruses have occurred in Australia. Higher crude seropositivity was found in Australian blood donors residing in high-risk areas compared to low-risk areas. The difference in seropositivity between high- and low-risk areas suggest local infection occurring in these areas. Of the three viruses analysed, JEV is the only one that is vaccine preventable, highlighting the importance of mosquito-bite prevention, in addition to vaccination, as a public health intervention for higher-risk populations.