RRV is an RNA
alphavirus, endemic in Australia. It causes arthralgias, fatigue, rashes and
polyarthritis. In rare cases, it causes splenomegaly, hematuria, meningitis and
number of species of mosquitoes are known to act as vectors in viral
transmission. However, the most common species acting as vectors include: Ochlerotatus vigilax, Ochlerotatus camptorhynchus
and Culex annulirostris.
period is usually between 3 and 21 days. The virus is rarely seen among
children. Diagnosis is usually confirmed with the presence of specific
antibodies to the Ross River virus (RRV)
In people with an on-going or past
infection, there is usually an increase in the RRV IgM (Immunoglobulin M)
antibodies. Diagnosis is usually done through an IFA (Immunofluorescence
Antibody Assay) test.
There are no
curative therapies available and the goal of treatment is to manage the
symptoms like joint pains and maintain joint mobility. Paracetemol and other
NSAIDS (non-steroidal anti-inflammatory drugs) are useful in pain management.
Recovery in mild cases takes as less than
a month. In more severe cases, joint pains continue up to 6 months. Complete
recovery is seen in almost all cases. Infection usually implies lifelong
In May 2014, the
Australian Red Cross Blood Service received information about a blood donor who
had developed fatigue and arthralgia, which was subsequently diagnosed as acute
RRV infection. PathWest Laboratory Medicine WA detected RRV IgM antibodies
using an IFA test. However, no RRV antibodies were detected with an in-house
hemagglutination inhibition (HI) antibody test 10 days after blood donation.
RRV IgM antibodies are usually detected by IFA test within a few days of
infection and IFA tests are generally more reliable. The HI antibody test
detects for IgG (Immunoglobulin G) antibodies, which usually appear a few weeks
after the IgM antibodies.
protocols do not permit donors diagnosed with RRV infection to donate fresh
components for 4 weeks after recovery. The components from the infected
donation were located. The RBCs (red blood cells) had been transfused to a
patient with myelodysplastic syndrome on 12 March 2014. Myelodysplastic
syndrome is associated with chronic fatigue and joint pains and the patient
reported worsening symptoms post-transfusion. The patient was tested for RRV on
28 May 2014 and a detectable level of RRV IgM antibodies was found. This
indicated the presence of RRV infection in recent months.
donor's archived sample was retrieved and sent to the Victorian Infectious
Diseases Reference Laboratory for RRV serological tests and RT-PCR (Reverse
transcription polymerase chain reaction) analysis. Though the sample tested
negative for RRV IgM and IgG, the RRV RNA was detected through two in-house
RT-PCR tests and verified through sequencing.
Possibility of Transfusion Transmission of RRV
Since 1972 when
RRV was first reported in humans, an understanding of the epidemiology and
spread of the disease has increased. RRV is the most common mosquito-borne
disease in Australia. Transfusion transmission of RRV was considered a
theoretical possibility. The new evidence now confirms that RRV can be
transmitted via transfusions. This case is the first confirmed case of
Lab testing for
RRV is not done during the donation process and there is no validated blood
screening for RRV. Donors with symptoms are not permitted to donate. However,
most RRV cases are asymptomatic and viremia is present in the incubation
period. If infected donors report subsequent symptoms, the donated blood and
components can be immediately recalled. The Australian Blood Service has
standards regulating blood donation, which requires donors to reveal recent
infections but in this case, the donor developed the symptoms post-donation.
The information was received 2 months post-donation by which time the blood had
already been transfused. Blood Services is now strengthening its message to
donors regarding reporting of subsequent illness post-donation.
This incident has now raised questions regarding
lab screening for RRV infections. However, the feasibility factor needs to be
taken into account. Nucleic Acid Testing (NAT) for RRV is not yet validated and
the costs are prohibitive. Though Australia records nearly 5000-mosquito
related RRV notifications per year, transmission via transfusion is a rare
incidence. It should also be noted that no blood transfusion is without risk
and a transfusion should be provided only when the benefit outweighs the risk
after a careful clinical evaluation.