19.1

Question 1

viruses causing fever, arthritis and rash

Answer 1

chikungunya virus
ross river
barmah forest

Question 2

chikungunya

Answer 2

mosquito vector - aedes species

cause of illness in returned travellers

Question 3

main resevoir of chikungunya

Answer 3

monkeys

Question 4

incubation period of chikungunya

Answer 4

1-12 days

Question 5

chikungunya symptoms

Answer 5

initially fever and chills, rash (often similar to dengue infection)
after a few days, fever may abate and recrudesce - ‘saddleback fever curve
sever arthritis most commonly seen in adults - can be very debilitating
headache, photophobia, retro-orbital pain, sore throat may also occur

Question 6

chikungunya rash

Answer 6

usually arises on face and neck, maculopapular or macular, may be pruritic
petechiae also sometimes seen
rash may spread to trunk and limbs

Question 7

chikungunya arthritis

Answer 7

polyarticular, favouring small jonts
duration of 1 week to 6 months
sever arthritis most commonly seen in adults

Question 8

mainstay of chikungunya diagnosis

Answer 8

serology

Question 9

chikungunya diagnosis

Answer 9

serology - mainstay of diagnosis, detection of virus specific IgM in serum
PCR - PCR of plasma can be useful early in course of infection. patients usually viraemic for first 48 hours of illness
viral culture - not routinely performed, required specialist lab facilities

Question 10

is CHIK notifiable in WA

Answer 10

yes

Question 11

ross river virus

Answer 11

also known as epidemic polyarthritis
mosquito vectors - culex and aedes species
occurs throughout australia, including WA
marsupial reservoir
important cause of acute arthralgia and arthritis in WA

Question 12

geography of ross river

Answer 12

south west - RRV most active in the late spring and summer
northern WA - most active during and after set seasons
interior WA - most active late summer and autumn

Question 13

incubation period of ross river

Answer 13

7-9 days

Question 14

symptoms of ross rriver

Answer 14

most people infected are ether asymptmatc or onlydevelop mld symptoms
arthritis typically affects peripheral joints, knees, ankles, wrists, fingers - often symmetrical
joint involvement varies in severity, from tenderness and minor restriction of movement to severe swelliing, effusion and redness
maculopapular rash and fever occurs in approx 50%
fatigue also common
most commonly affects patents 20-60 years of age
most patients recover fully by 3-6 months

Question 15

mst patents reciver from ross river in

Answer 15

3-6 months

Question 16

ross rver most commonly affects

Answer 16

patients 20-60 years of age

Question 17

barmah forest virus

Answer 17

also causes epidemic poyarthritis
occurs throughout australia including WA
similar vectors to RRV - aedes and culex

Question 18

symptoms of barmah forest virus

Answer 18

most people infected remain asymptomatic or develop mild symptoms
clinical features similar to RRV, however tend to be milder and shorter in duration
rash may be more marked in BFV

Question 19

lab diagnosis of RRV and BFV

Answer 19

serology is mainstay of diagnosis - detection of specific IgM in acute-phase serum is suggestive of possible recent infection
demonstration of seroconversion by collecting acute and convalescent serum (>10 days later) specimens is essential to confirm the diagnosis
PCR and viral culture is of limited use in routine diagnosis
RRV and BFV are both notifiable disease in WA

Question 20

arboviruses causing fever, rash and arthritis mainly belng to

Answer 20

alphavirus group

Question 21

which viruses are notifiable in WA

Answer 21

all three - CHIK, RRV and BFV