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Frequently Asked Questions
What is melioidosis?
Melioidosis, also called Whitmore’s disease, is an infectious
disease caused by the bacterium Burkholderia pseudomallei.
Melioidosis is clinically and pathologically similar to glanders
disease, but the ecology and epidemiology of melioidosis are different
from glanders. Melioidosis is predominately a disease of tropical
climates, especially in Southeast Asia where it is endemic. The
bacteria causing melioidosis are found in contaminated water and
soil and are spread to humans and animals through direct contact
with the contaminated source. Glanders is contracted by humans
from infected domestic animals.
Why has melioidosis
become a current issue?
Burkholderia pseudomallei is an organism that has been
considered as a potential agent for biological warfare and biological
terrorism.
How common is melioidosis
and where is it found?
Melioidosis is endemic in Southeast Asia, with the greatest concentration
of cases reported in Vietnam, Cambodia, Laos, Thailand, Malaysia,
Myanmar (Burma), and northern Australia. Additionally, it is seen
in the South Pacific, Africa, India, and the Middle East. In many
of these countries, Burkholderia pseudomallei is so prevalent
that it is a common contaminate found on laboratory cultures.
Moreover, it has been a common pathogen isolated from troops of
all nationalities that have served in areas with endemic disease.
A few isolated cases of melioidosis have occurred in the Western
Hemisphere in Mexico, Panama, Ecuador, Haiti, Brazil, Peru, Guyana,
and in the states of Hawaii and Georgia. In the United States,
confirmed cases range from none to five each year and occur among
travelers and immigrants.
How is melioidosis
transmitted and who can get it?
Besides humans, many animal species are susceptible to melioidosis.
These include sheep, goats, horses, swine, cattle, dogs, and cats.
Transmission occurs by direct contact with contaminated soil and
surface waters. In Southeast Asia, the organism has been repeatedly
isolated from agriculture fields, with infection occurring primarily
during the rainy season. Humans and animals are believed to acquire
the infection by inhalation of dust, ingestion of contaminated
water, and contact with contaminated soil especially through skin
abrasions, and for military troops, by contamination of war wounds.
Person-to-person transmission can occur. There is one report of
transmission to a sister with diabetes who was the caretaker for
her brother who had chronic melioidosis. Two cases of sexual transmission
have been reported. Transmission in both cases was preceded by
a clinical history of chronic prostatitis in the source patient.
What are the
symptoms of melioidosis?
Illness from melioidosis can be categorized as acute or localized
infection, acute pulmonary infection, acute bloodstream infection,
and chronic suppurative infection. Inapparent infections are also
possible. The incubation period (time between exposure and appearance
of clinical symptoms) is not clearly defined, but may range from
2 days to many years.
Acute, localized infection: This
form of infection is generally localized as a nodule and results
from inoculation through a break in the skin. The acute form of
melioidosis can produce fever and general muscle aches, and may
progress rapidly to infect the bloodstream.
Pulmonary infection: This
form of the disease can produce a clinical picture of mild bronchitis
to severe pneumonia. The onset of pulmonary melioidosis is typically
accompanied by a high fever, headache, anorexia, and general muscle
soreness. Chest pain is common, but a nonproductive or productive
cough with normal sputum is the hallmark of this form of melioidosis.
Acute bloodstream infection: Patients
with underlying illness such as HIV, renal failure, and diabetes
are affected by this type of the disease, which usually results
in septic shock. The symptoms of the bloodstream infection vary
depending on the site of original infection, but they generally
include respiratory distress, severe headache, fever, diarrhea,
development of pus-filled lesions on the skin, muscle tenderness,
and disorientation. This is typically an infection of short duration,
and abscesses will be found throughout the body.
Chronic suppurative infection:
Chronic melioidosis is an infection that involves the organs of
the body. These typically include the joints, viscera, lymph nodes,
skin, brain, liver, lung, bones, and spleen.
How is melioidosis
diagnosed?
Melioidosis is diagnosed by isolating Burkholderia pseudomallei
from the blood, urine, sputum, or skin lesions. Detecting
and measuring antibodies to the bacteria in the blood is another
means of diagnosis..
Can melioidosis
be spread from person to person?
Melioidosis can spread from person to person by contact with
the blood and body fluids of an infected person. Two documented
cases of male-to-female sexual transmission involved males with
chronic prostatic infection due to melioidosis.
Is there a way
to prevent infection?
There is no vaccine for melioidosis. Prevention of the infection
in endemic-disease areas can be difficult since contact with contaminated
soil is so common. Persons with diabetes and skin lesions should
avoid contact with soil and standing water in these areas. Wearing
boots during agricultural work can prevent infection through the
feet and lower legs. In health care settings, using common blood
and body fluid precautions can prevent transmission.
Is there a treatment
for melioidosis?
ost cases of melioidosis can be treated with appropriate antibiotics.
Burkholderia psuedomallei, the organism that causes melioidosis,
is usually sensitive to imipenem, penicillin, doxycycline, amoxicillin-clavulanic
acid, azlocillin, ceftazidime, ticarcillin-vulanic acid, ceftriaxone,
and aztreonam. Treatment should be initiated early in the course
of the disease. Although bloodstream infection with melioidosis
can be fatal, the other types of the disease are nonfatal. The
type of infection and the course of treatment can predict any
long-term sequelae.
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