To the Editor: We report an unusual case of Ross River virus (RRV) disease in a 7-year-old child. The patient presented to her general practitioner with fever, rash and pain in the lower limbs. Swelling of the joints of the hands and left knee was found, with a widespread rash that covered the trunk, limbs and face. The rash comprised lesions of varying types, including maculopapular, vesicular and petechial lesions (Box).

Rash in a child with Ross River virus disease

The general practitioner transferred the patient to the state tertiary paediatric service. No antibiotics were given before transfer. On arrival at Princess Margaret Hospital for Children, Perth, the patient was unwell, with a fever of 38°C. A provisional diagnosis was made of septicaemia (probably meningococcal), and treatment was begun with intravenous ceftriaxone. Extensive investigations were performed, but results of all initial serological, polymerase chain reaction and culture investigations were negative.

Rheumatology review was requested because of the prominent arthritic component of the illness. This revealed widespread polyarthritis, and the illness was felt to be a reactive or post-infectious process.

The child’s family raised the possibility of RRV disease, as her grandmother had had this disease several years previously, and the child had stayed overnight at her grandmother’s home in a coastal lake area 2 weeks before disease onset. The area had abundant mosquitoes, as well as kangaroos, which are vertebrate amplifiers for RRV.1

Serological tests for RRV were performed 3 days after admission, and were negative for IgG and positive for IgM. Repeat serological testing during convalescence showed a fourfold rise in IgG titre (from 80 to 320), confirming the diagnosis of RRV disease.

The patient’s rash decreased over several days. She had persistent synovitis in the left knee at review 3 weeks after admission. At review at 8 weeks all symptoms and signs had resolved, and she had full function.

This case highlights the fact that, while RRV disease with severe symptoms and arthritic manifestations is uncommon in children, it nevertheless should still be considered in the differential diagnosis of children with a febrile and arthritic disease.1,2 This child’s illness appears to have been a reactive vasculitis and polyarthritis, which, while well recognised with other infections, is not well described in association with RRV disease in children. RRV arthritis is caused by joint infection, and treatment is currently based on empirical anti-inflammatory regimens.

During the recent RRV disease epidemic in Western Australia, 1174 notifications for RRV disease were received between 1 October 2003 and 31 March 2004. Of these, 21 patients were aged 15 years or younger. Thus, while RRV disease is an infrequent illness in children, it does occur, and should be considered in the differential diagnosis of a child who presents with a febrile illness, rash and joint symptoms from an area with known autochthonous transmission of RRV.