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Survival of dengue virus in the urine of acutely-infected patients – implications for pathogenesis and for a possible unrecognized mode of transmission for an arthropod-borne virus

Abstract number: 1732_47

Yingsiwaphat V., Siriyasatien P., Arunyingmongkol K., Krajiw S., Pupaibool J., Nisalak A., Pancharoen C., Thisyakorn U., Kulwichit W.

Objectives: Dengue virus infection is considered the world's most important arthropod-borne disease. We have earlier reported a pilot study that dengue, like some other viruses, can be detected by RT-PCR in urine from a number of patients, even in an early postfebrile period. Here we wish to report a follow-up study with more cases and with our success in isolating the virus from early and late urine specimens of acutely-infected patients.

Methods: Hospitalised patients suspected of dengue infection were enrolled. Diagnosis was confirmed by standard criteria of enzyme-linked immunosorbent assay (ELISA) and/or haemagglutination inhibition test (HI). Patients with negative dengue serologies served as negative controls. Dengue-specific PCR, with primers targeting conserved sequences in the 3'-untranslated region, was performed in urine specimens with a strict and properly-evaluated protocol. Pairs of febrile and postfebrile urine specimens from 1 adult and 3 paediatric dengue cases with positive dengue-specific PCR in urine, together with those of 1 adult and 2 paediatric negative controls, were processed and then employed for Aedes aegypti intrathoracic inoculation. To minimise urinary toxicity to mosquitoes, 3 forms of processed urine were used: diluted urine pellets, diluted urine supernatants filtered though 0.2-mm membrane, and diluted urine supernatants mixed with antimicrobials. Each form of each specimen was inoculated into 20 mosquitoes. Surviving mosquitoes were dissected 14 days after inoculation. Dengue-specific PCR was performed on extracts from the body parts of all injected mosquitoes.

Results: Of 237 dengue patients enrolled, the virus was detected in 122/189 paediatric and 20/48 adult urine specimens by PCR (64.55% and 41.67% respectively). Live dengue viruses were detected in all febrile and postfebrile urine specimens of dengue cases but in none of negative controls (Table). The virus was isolated as late as 14 days after defervescence. Filtered urine supernatants served as the best specimen type, with the least urinary toxic effects to mosquitoes.

Specimens#cases with virus isolated/total # cases
urine pellets urine supernatants
Antimicrobials addedMicrofiltration (0.2 m)  
Dengue
  febrile urine1/4 (25%)3/4 (75%)4/4 (100%)
  postfebrile urine0/4 (0%)3/4 (75%)4/4 (100%)
Nondengue
  febrile urine0/3 (0%)0/3 (0%)0/3 (0%)
  postfebrile urine0/3 (0%)0/3 (0%)0/3 (0%)

Conclusion: Dengue virus is not only excreted in urine in at least half of the patients, but it is also live and culturable. These findings have implications for dengue pathogenesis and for public health. Urine is implicated as a potential mode of transmission for certain viruses. Whether the arthropod-borne dengue will be added to the list is subject to further investigation.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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