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Published Date: 2011-04-12 15:22:49
Subject: PRO/EDR> Melioidosis - Australia (02): (NT)
Archive Number: 20110412.1155

MELIOIDOSIS - AUSTRALIA: (NORTHERN TERRITORY)
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International Society for Infectious Diseases
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Date: Thu 7 Apr 2011
Source: ABC News (Australian Broadcasting Corporation) [edited]
http://www.abc.net.au/news/stories/2011/04/07/3185292.htm?section=justin

The Health Department is warning about the ongoing risk posed by a
potentially deadly soil disease, which has infected 56 people in the
Northern Territory this wet season. Melioidosis claims a number of
lives each year in the Territory but its impact has been more
significant in the past 2 wet seasons with a record number of
infections, including some in Central Australia.

"It is caused by bacteria that live deep in the soil of the Top End
[the northern portion of the Northern Territory]. during the dry
season but come to the surface with water and mud after heavy
rainfall," Centre for Disease Control director Dr Vicki Krause said.
"Melioidosis can cause severe pneumonia and blood infection,
particularly in people with underlying health conditions that impair
the immune system."

People can become infected by walking in muddy water, handling muddy
items, or breathing air-borne particles while using high-powered
hoses. Dr Krause advised people to take precautions against the
disease by wearing waterproof shoes, gloves, and masks when gardening
or cleaning up after floods.

People most at risk include those with underlying conditions, such as
diabetes, heavy alcohol intake, cancer, advanced age, kidney or lung
disease, and those being treated for cancer and on long-term steroid
therapy medicines, she said.

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Communicated by:
ProMED-mail
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[The HealthMap/ProMED-mail interactive map of Australia is available
at http://healthmap.org/r/007y. A map of the Top End of the Northern
Territory can be seen at
http://www.bushwalkingholidays.com.au/images/top_end_map.jpg. -
Sr.Tech.Ed.MJ]

[Most of the reports of melioidosis from Australia originate in the
Northern Territory, however, the disease is also endemic in
Queensland, which is east of the Northern Territory. The disease
usually occurs during the rainy season and may be accentuated by
extreme flooding from rain and also from tsunamis as occurred in 2005
in Thailand. A few cases were diagnosed after survivors returned to
their home country of Finland.

_Burkholderia pseudomallei_ exists as an environmental saprophyte
living in soil and surface water in endemic areas (South East Asia and
northern, tropical Australia), particularly in rice paddies. In
endemic countries, the organism exists primarily in focal areas and is
not equally distributed throughout the landscape. Sporadic cases have
been reported to have been acquired in parts of Africa and the
Americas. The organism may exist in a viable, non-cultivable state in
the environment, interacting with other organisms, particularly
protozoa, which might explain its adaptation to an intracellular
niche. 2 outbreaks in Australia have also implicated potable water
supplies rather than surface water as a potential source of the
infection.

Melioidosis is a disease of the rainy season in the endemic areas. It
mainly affects people who have direct contact with soil and water.
Many have an underlying predisposing condition such as diabetes
(commonest risk factor), renal disease, cirrhosis, thalassemia,
alcohol dependence, immunosuppressive therapy, chronic obstructive
lung disease, cystic fibrosis, and excess kava consumption. Kava is an
herbal member of the pepper family that can be associated with chronic
liver disease.

Melioidosis may present at any age, but peaks in the 4th and 5th
decades of life, affecting men more than women. In addition, although
severe fulminating infection can and does occur in healthy
individuals, severe disease and fatalities are much less common in
those without risk factors.

The most commonly recognized presentation of melioidosis is
pneumonia, associated with high fever, significant muscle aches, chest
pain, and -- although the cough can be nonproductive -- respiratory
secretions can be purulent, significant in quantity, and associated
with on-and-off bright red blood. The lung infection can be rapidly
fatal -- with bacteremia and shock -- or somewhat more indolent.

Acute melioidosis septicemia is the most severe complication of the
infection. It presents as a typical sepsis syndrome with hypotension,
high cardiac output, and low systemic vascular resistance. In many
cases, a primary focus in the soft tissues or lung can be found. The
syndrome, usually in patients with risk factor comorbidities, is
characteristically associated with multiple abscesses involving the
cutaneous tissues, the lung, the liver, and spleen and a very high
mortality rate of 80 to 95 per cent. With prompt optimal therapy, the
case fatality rate can be decreased to 40 to 50 per cent.

The melioidosis bacillus is intrinsically insensitive to many
antimicrobials. It should be noted that bioterrorism strains may be
engineered to be even more resistant. _B. pseudomallei_ is usually
inhibited by tetracyclines, chloramphenicol,
trimethoprim-sulfamethoxazole (SXT), antipseudomonal penicillins,
carbapenems, ceftazidime, and amoxicillin/clavulanate or
ampicillin/sulbactam. Ceftriaxone and cefotaxime have good in vitro
activity but poor efficacy; and cefepime did not appear, as well, to
be equivalent to ceftazidime in a mouse model. The unusual
antimicrobial profile of resistance to colistin and polymyxin B and
the aminoglycosides but sensitivity to amoxicillin/clavulanate is a
useful tool to consider in treatment of infection with the organism.

The randomized and quasi-randomized trials comparing melioidosis
treatment have been reviewed, and it was found that the formerly
standard therapy of chloramphenicol, doxycycline, and SXT combination
had a higher mortality rate than therapy with ceftazidime,
imipenem/cilastatin, or amoxicillin/clavulanate (or
ampicillin/sulbactam). The betalactam-betalactamase inhibitor therapy,
however, seemed to have a higher failure rate.

Source: Tolaney P, Lutwick LI: Melioidosis. In: Lutwick LI, Lutwick
SM (eds). Bioterror: the weaponization of infectious diseases. Totowa
NJ: Humana Press, 2008 pp 145-58. - Mod.LL]

See Also