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Dispatch
Scrub Typhus in the Torres
Strait Islands of North Queensland, Australia
Antony G. Faa,* William J.H. McBride,† Gaynor Garstone,‡ Robert E.
Thompson,* and Peter Holt*
*Thursday Island Hospital, Queensland, Australia; †Cairns Base Hospital,
Queensland, Australia; and ‡Darnley Island Health Centre, Queensland,
Australia
Suggested citation for this article: Faa AG,
McBride WJH, Garstone G, Thompson RE, Holt P. Scrub typhus in the Torres
Strait Islands of North Queensland, Australia. Emerg Infect Dis [serial
online] 2003 Apr [date cited]. Available from: URL: http://www.cdc.gov/ncidod/EID/vol9no4/02-0509.htm
Scrub typhus, caused
by Orientia tsutsugamushi, occurs throughout Southeast Asia.
We descript ten cases that occurred in the Torres Strait islands of
northern Australia during 2000 and 2001. Preceding heavy rain may have
contributed to the outbreak. The successful use of azithromycin in two
pediatric patients is also reported.
Scrub typhus is a rickettsial disease caused by the bacteria Orientia
tsutsugamushi and is transmitted to humans from the bite of a larval
trombiculid mite. The disease is distributed throughout Southeast Asia
and is restricted by the distribution of the host mite (1).
Scrub typhus has been recognized as being endemic to north Queensland
since the 1920s (2). More recently, the disease has been
recognized in the Northern Territory (3) and the northwest
of western Australia (4). In north Queensland the disease
is most commonly recognized between Ingham and Cooktown. In a recent review
of cases from north Queensland, none were reported outside of this area
(5). In March 2000, scrub typhus was diagnosed in a visitor
to Torres Strait from Papua New Guinea. Additional cases were subsequently
diagnosed in residents of Torres Strait. We describe a cluster of cases
from Darnley Island in the Torres Strait. This island, and possibly others
in the Torres Strait, should now be considered as scrub typhus–endemic
foci.
Case Studies
A 35-year-old man, a visitor from Papua New Guinea, arrived at the Darnley
Island Health Centre in March 2000, complaining of headache and symptoms
of fever. He had arrived on Darnley Island 24 days before onset of illness.
He began a course of oral quinine for suspected malaria but remained ill
and was transferred to Thursday Island Hospital. He was noted to be febrile
(40.2°C) and had marked conjunctival injection. No obvious focus of infection
was evident. The day after admission he was still febrile and was given
Timentin (ticarcillin plus clavulinic acid), gentamicin, and doxycycline.
His condition gradually improved, and the fever subsided in 5 days. Scrub
typhus serologic test results were strongly positive (Table,
patient 1).
A 19-year-old patient (patient 2) was transferred from Murray Island
to the Thursday Island Hospital in May 2000. He had been ill for 12 days
with fever, frontal headache, and intermittent vomiting. He had a documented
temperature of 40.1°C before admission to hospital and had been treated
symptomatically with aspirin and metoclopromide. He had not left Murray
Island for several months and had never traveled to Papua New Guinea.
He denied knowledge of any mite bites. On admission he looked ill and
complained of lethargy; his temperature was 39.4°C. He had slight conjunctival
injection and mild tenderness in the right upper quadrant of his abdomen.
A typical black eschar approximately 0.5 cm in diameter was found on his
upper right thigh with associated tender right inguinal lymphadenopathy.
Tests indicated a normal leukocyte count (9.8 x 109/L), thrombocytopenia
(platelet count 79,000/µL), increased creatinine (0.14 mmol/L), and abnormal
liver function tests ( -glutamyl
transferase 55 U/L, normal <50; alanine aminotransferase 280 U/L, normal
<45; aspartate aminotransferase 223 U/L, normal <40). He received
doxycyline, became afebrile after 48 hours, and made an uncomplicated
recovery
A 28-year-old woman (patient 4) arrived at Darnley Island Health Centre
in January 2001 with her 9-year-old son (patient 5); both complained of
being ill for approximately 1 week. They reported fevers, headache, and
generalized myalgia. The child also complained of vomiting and was noted
to have a dry cough with some rhinorrhea. He was started on a course of
amoxicillin. The next day, when seen at the visiting doctors clinic, both
mother and son were given oral quinine to treat possible malaria. Over
the next few days, both remained febrile with temperatures up to 40°C.
They were transferred to Thursday Island Hospital. The mother had a typical
black eschar on her left breast (Figure 1) with
associated regional lymphadenopathy. She also had conjunctival injection.
Oral doxycycline was administered, and the fever resolved over 3 days.
Her son was treated with azithromycin (250 mg a day for 3 days) and became
afebrile within 24 hours.
In the next 3 weeks, four more patients (one adult [patient 7], two teenagers
[patients 6 and 8], and one 5-year-old child [patient 9]) arrived at Darnley
Island Health Centre with nonspecific febrile illnesses associated with
headache. Two had eschars (one located on the scrotum and another on the
scalp) with associated regional lymphadenopathy. One patient had conjunctival
injection, and another had a fine truncal rash. Two were treated with
oral doxycycline and became well soon after starting treatment. Patient
6 was successfully treated with azithromycin (1,000 mg as a single dose).
Patient 9 had been given a course of oral and intramuscular penicillin
before scrub typhus was suspected and remained ill with fevers and abdominal
pain (with right upper quadrant tenderness). He was transferred to the
hospital 2 weeks after being initially seen but was afebrile on admission
and remained well with no additional treatment. An additional case of
scrub typhus (patient 10) was documented in April 2001.
Epidemiologic Findings and
Community Interventions
After recognition of this cluster of scrub typhus cases, a doctor and
indigenous health worker traveled to Darnley Island to interview patients
and educate the local community about the disease. The six patients had
not left Darnley Island in the 6 weeks before becoming ill. The patients
lived on different parts of the island, and no common area was visited
before illness onset. Patient 4 was an exception and had harvested mangoes
in an area of jungle close to her house where her son (patient 5) played.
The transmission of scrub typhus on Darnley Island probably occurred in
the densely vegetated areas close to most domestic dwellings on the island.
A public meeting was held, which focused on increasing the general awareness
of the signs and symptoms of scrub typhus and the importance of early
diagnosis and treatment. The meeting included local indigenous health
workers. Aspects of personal protection against mite bites were also stressed,
including wearing protective boots and trousers and using insect and mite
repellants when going into potential areas of transmission.
Conclusions
The Torres Strait islands (Figure 2) lie between
Cape York Peninsula in Queensland and Papua New Guinea. The islands have
a population of approximately 9,000 mainly indigenous inhabitants. Approximately
half of the people live on or near Thursday Island, which is the main
commercial and government center. A 38-bed general hospital is located
there. The other half of the population lives on the 15 outer island communities
that stretch between the Australian and Papua New Guinea mainland. Health
centers are located on each of these islands and are staffed by remote
area nurses, indigenous healthcare workers, or both.
The cases of scrub typhus infection we describe are not the first to
be described from the Torres Strait islands. Scrub typhus was previously
reported in the 1950s, with a single case from Hammond Island (near Thursday
Island), and another in a diver from a lugger “near Darnley Island” (2).
We describe at least two islands where transmission of scrub typhus occurred
in the Torres Strait during the wet seasons of 2000 and 2001. One infection
occurred on Murray Island, and seven occurred on Darnley Island. Another
patient lived on Thursday Island but traveled to several outer islands
in the weeks before becoming ill and probably acquired his infection on
Darnley Island. The occurrence of six cases of scrub typhus on Darnley
Island over a 3-week period is important, representing the infection of
nearly 2% of the total population (375) (6). Rainfall
for the region was well above average in November and December 2000, the
beginning of the wet season (7). The resulting dense
vegetation would have provided favorable conditions for the transmission
of disease. We believe that O. tsutsugamushi has probably existed
in the region for many decades, rather than having been recently introduced,
and climatic conditions favored the transmission to humans in the early
part of 2001.
Our series included two children and one young teenager. A 9-year-old
boy and 14-year-old girl responded well to treatment with azithromycin.
Azithromycin has been used successfully in the treatment of scrub typhus
in a small number of pregnant women (8), but to our knowledge
these are the first published cases of its clinical use in children with
the disease.
Acknowledgments
We thank healthcare workers, nurses, and other doctors
involved in diagnosis, patient care, and public education, including
Russell Carter, Sook Fun Soo, Dave Harley, Anna Levi, and Diai Luffman;
the laboratory staff at Thursday Island Hospital; Rhys Davies; Carmel
Taylor and her staff at the Queensland Reference Laboratory for Rickettsial
Diseases, Brisbane; Stephen Graves and staff at the Australian Rickettsial
Reference Laboratory; Victoria for performing PCR tests; and the residents
of Erub and the Darnley Island Health Council for their support and
help in community awareness.
Dr Faa is a general practitioner currently working at
St Mary's Hospital in Papua New Guinea. His interests include rural
and remote medicine in indigenous populations and tropical medicine.
References
- Traub R, Wisseman CL Jr. The
ecology of chigger-borne rickettsiosis (scrub typhus). J Med Entomol
1974;11:237–303.
- Derrick EA. The incidence and distribution of scrub typhus in north
Queensland. Aust Ann Med 1961;10:256–67.
- Currie B, O’Connor L, Dwyer B. A
new focus of scrub typhus in tropical Australia. Am J Trop Med Hyg
1993;49:425–9.
- Quinlan ML, Chappell T, Golledge CL. Scrub typhus in Western Australia.
Commun Dis Intell 1993;17:570–1.
- McBride WJ, Taylor CT, Pryor JA, Simpson JD. Scrub
typhus in north Queensland. Med J Aust 1999;170:318–20.
- Torres Strait Regional Authority. Island Coordinating Council. Population—Torres
Strait communities, Housing Report; 1996. Available from: URL: http://www.tsra.gov.au/Darnley.htm
- Australian Bureau of meteorology. Available from: URL: ftp://www.bom.gov.au/anon/home/ncc/www/rainfall/percent/month/blkwht/history/qd/
- Choi EK, Pai H. Azithromycin
therapy for scrub typhus during pregnancy. Clin Infect Dis 1998;27:1538–9.
| Table.
Demographic, clinical and serologic data for patients with scrub typhus,
Torres Strait islands, Queensland, Australia |
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Orientia tsutsugamushi antibody
titera
(d after onset)
|
| |
|
|
|
|
|
| Patient no. |
Age (y)/sex
|
Date
|
Island
|
Eschar
|
0–7
|
8–14
|
15–21
|
22–28
|
>29
|
|
|
1
|
35/male
|
Mar 2000
|
Darnley
|
No
|
|
8,192
|
|
|
8,192
|
|
2
|
19/male
|
May 2000
|
Murray
|
Yes
|
<64
|
4,096
|
|
|
4,096
|
|
3
|
29/maleb
|
Aug 2000
|
—
|
No
|
1,024
|
1,024
|
|
|
1,024
|
|
4
|
28/female
|
Jan 2001
|
Darnley
|
Yes
|
|
NR
|
|
512
|
|
|
5
|
9/male
|
Jan 2001
|
Darnley
|
No
|
|
|
256
|
|
256
|
|
6
|
14/female
|
Jan 2001
|
Darnley
|
No
|
|
512
|
512
|
|
|
|
7
|
36/male
|
Jan 2001
|
Darnley
|
Yes
|
NR
|
|
512
|
|
|
|
8
|
19/male
|
Jan 2001
|
Darnley
|
No
|
64c
|
|
|
256
|
|
|
9
|
5/male
|
Feb 2001
|
Darnley
|
Yes
|
|
>1,024
|
>1,024
|
|
|
|
10
|
30/maleb
|
Apr 2001
|
—
|
Yes
|
NRc
|
128
|
|
|
|
|
| aSerologic tests
were performed by using an immunofluorescent antibody method; NR,
nonreactive. |
| bPatient visited
several islands in 3 weeks before becoming ill. |
| cPolymerase chain
reaction for scrub typhus positive (by using primers for 56-kDa antigen
gene). |
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