Medicus, Vol. 14 No. 1_ARI, 2005.
Review article
Influenza - Always an Illness of Interest
Ivan Puljiz
Ilija Kuzman
Abstract
Infl uenza is an acute respiratory disease
caused by infl uenza viruses. Infl uenza viruses are classifi ed
into three distinct types on the basis of major antigens.
Infl uenza A viruses are further divided into subtypes
according to their hemagglutinin (HA) and neuraminidase
(NA) activity. Infl uenza occurs in epidemics and pandemics.
Infl uenza epidemics are regularly associated with increased
morbidity and mortality especially in elderly and persons
with certain high-risk medical conditions. There have been
three pandemics during the past century – in 1918, 1957,
and 1968. The greatest pandemic in recorded history
occurred in 1918 when more than 20 million deaths
were reported worldwide. Infl uenza virus changes antigen
structure of two external glycoproteins, HA and NA, and is
referred to as antigenic drift or antigenic shift. Antigenic
drift refers to relatively minor antigenic changes that occur
frequently within the HA and/or NA of the virus. The major
antigenic shifts that herald pandemic infl uenza occur only
with infl uenza A viruses. Infection induces production
of both systemic and local antibodies, as well as T-cell
responses. Initially, systemic symptoms predominate, while
respiratory symptoms appear later. Infl uenza is associated
with pulmonary complications, particularly among elderly
and persons with chronic disorders. The diagnosis can be
made on the basis of clinical features, epidemiological
history, and confi rmed with a variety of virology techniques
(virus isolation, detection of viral antigen, detection of viral
nucleic acid, and serology). The treatment of infl uenza
is symptomatic, and includes resting, fl uid replacement,
antipyretics, and antitussives. Antiviral drugs are
recommended for older patients and persons with chronic
conditions, but require early initiation of therapy. The M2
ion channel inhibitors, i.e. amantadine and rimantadine,
are active against infl uenza A virus. The neuraminidase
inhibitors, zanamivir and oseltamivir, are active against
all strains of infl uenza A viruses, and infl uenza B viruses.
Antiviral agents are effective in infl uenza prophylaxis. In
patients with bacterial complications, antibiotics should
be administered. The most effective and simplest measure
available for the control of infl uenza is vaccination. Infl uenza
vaccination is recommended for persons at increased risk
for complications, and persons who can transmit infl uenza
to those at high risk.
Keywords
infl uenza; hemagglutinin; neuraminidase; pandemic
Hrčak ID:
18827
URI
Publication date:
26.1.2005.
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