Legionellosis is an infection
caused by the bacterium Legionella pneumophila. The disease
has two distinct forms, Legionnaires’ disease and Pontiac
fever. Legionnaires’ disease is a severe pneumonia, while
Pontiac fever is a mild, non-pneumonia influenza-like illness.
Legionnaires' disease acquired its name in 1976 when an
outbreak of pneumonia occurred among delegates attending
a convention of the American Legion in Philadelphia. Later,
the bacterium causing the illness was named Legionella.
Colonies
of Legionella pneumophila
Legionnaires'
disease usually begins with a headache, pain in the muscles and
a general feeling of unwellness. These symptoms are followed by
high fever (up to 40°-40.5°C or about 104°-105°F)
and shaking chills. Nausea, vomiting, and diarrhea may occur.
On the second or third day, dry coughing begins and chest pain
might occur. Difficulty with breathing is often reported. Most
patients develop pneumonia, a condition in which some of the lungs'
air sacs filled with fluid or pus, so air is excluded. The pneumonia
might involve both lungs and become so severe that hospitalization
is required. Pneumonia resulting from Legionnaires' disease is
similar to other forms of pneumonia. Therefore, laboratory tests
are necessary for a confident diagnosis. If left untreated, patients
can develop severe pneumonia that is not responsive to penicillins
or aminoglycosides. Legionnaires' disease also has the potential
to spread into other organ-systems of the body such as the gastrointestinal
tract and the central nervous system.
Realizing
the importance of identifying the Legionnaires’ disease
from the typical pneumonia, Dr Stacey Yong Foong Yee, a lecturer
in Monash University Malaysia, has been researching on Legionella
pneumophila for about 4 years now. Her research involves
identifying specific DNA marker to isolate Legionella pneumophila
in environmental and clinical samples. “It is important
to isolate Legionella especially in clinical samples.
If patients who suffered from Legionnaires’ disease are
not diagnosed accurately, they may suffer from severe complications
or lead to death”, said Dr Yong. The molecular techniques
are developed together with her co-researchers. These techniques
will help to speed up the detection process, and also to generate
more accurate qualitative data.
So,
how are these molecular techniques developed? By developing a
specific DNA marker using the advanced Polymerase Chain Reaction
(PCR) to detect Legionella pneumophila. Different microorganisms
have different DNA markers. The DNA marker of Legionella pneumophila
is designed based on its virulence genes which are responsible
for the disease.
“One
of the areas that encourage me to continue exploring is the possibility
of horizontal gene transfer (of the virulence genes) among pneumonia-causing
bacteria,” Dr Yong explained. “If this horizontal
gene transfer is proven to be possible, this will help us to understand
pneumonia patients who are infected with different types of pneumonia-causing
bacteria”, she added.
Dr
Yong is one of the few researchers in Malaysia who is working
on Legionella pneumophila. Her expertise is often sought
after by hospitals and industries.
Other
than the Legionella research project, Dr Yong is also
currently involved in research on viral indicators. This is a
group of viruses has been used as an indicator of the presence
of enteric viruses in water samples. “Research on viral
indicators is relatively new in our country with only one or two
groups of researchers working on it in the past,” she explained.
“We
are looking at the correlation between the viral indicators and
enteroviruses present in the environment”. Enteroviruses
are a group of viruses from the subgroup of picornaviruses,
which includes polioviruses, coxsackieviruses,
and echoviruses that infect the gastrointestinal tract
and often spread to other parts of the body, especially the nervous
system. The purpose of this research is to establish a ‘water
quality index’ for our country based on this indicator.
“Currently,
we are establishing microbiological and molecular techniques in
isolating and quantifying the viral indicators in treated water,
river water and seafood.”
When
asked what sparked her interest in working on these current researches,
Dr Yong replied, “because it concerns the public’s
health and the quality of life and there are always new things
to discover”. A real outcome of the viral indicator research
work could be the availability of safer drinking water and seafood
that are free from pathogenic viral contamination. This research
will also provide a clue on the required steps to be taken in
order to prevent sewage or fecal contamination of river water.
“Both
the Government and the public are growing more and more concerned
about public health and the quality of life. I believe that both
these projects will provide basic platforms for future investigations
into more specific or applied aspects of viral detection. There
are still plenty of areas to be explored.”
Dr Stacey Yong Foong
Yee is a lecturer at Monash University Malaysia. She received
both her BSc (Hons) and PhD from RMIT University, Australia.
Her main research interest is on clinical microbes, epidemiological
study of Legionella pneumophila, developing environment
diagnostic and detection kit, and water quality assessment
using viral indicators. She has been actively involved
in research activities and have several scientific papers
published. Her most recent one is entitled “Detection
and identification of Legionella using duplex
PCR targeting the 16S rRNA and ICM genes” which
can be found in the “The First Joint Congress of
the College of Pathologists & The Malaysian Institute
of Medical Laboratory Sciences, 16-18 December 2003, Kuala
Lumpur, Malaysia”.
