Biomedical Engineering Reference
In-Depth Information
about half of all patients. There are three presenta-
tions of Q fever pneumonia: pneumonia presenting
as a fever with no pulmonary symptoms, atypical
pneumonia, and rapidly progressive pneumonia.
Cough, usually non-productive, is present in
25-50% of those with radiographically confirmed
Q fever pneumonia. Pleuritic chest pain may
also occur. Rales are probably the most common
physical finding. Patients with rapidly progressing
pneumonia often have signs of pulmonary consol-
idation. Q fever infections are rarely fatal. Q fever
hepatitis occurs in about a third of all cases.
Q fever endocarditis is a rare complication, very
difficult to treat, and may require valve replace-
ment. Person-to-person transmission is rare, but
has been reported via tissue transplantation and
sexual contact. There are also psychological effects
to chronic Q fever infection, including depression
and mental status changes [5].
q6h and rifampin 600mg qd is also effective.
Chronic infection, especially involving endo-
carditis, often requires extended treatment and
should involve appropriate specialists [5].
4.9.6 Prophylaxis
Tetracycline 500mg q6h po
×
5 days or doxycy-
cline 100mg q12h po
5 days started 8-12 days
post exposure. Antibiotic prophylaxis must be
timed properly. Antibiotics given within the first
week following exposure will delay but not prevent
onset of illness [5].
×
4.10 Disease: Ricin Intoxication
4.10.1 Causative Agent
Ricin, a glycoprotein toxin derived from castor
plant beans, has great potential as a biological
agent due to its wide availability. Ricin produces its
damage by inhibiting cellular protein synthesis [5].
4.9.3 Diagnosis
Culture of
C. burnetii
is difficult. Diagnosis is typi-
cally made by antibody detection using any of a
variety of serologic means [5,11].
4.10.2 Clinical Description
The incubation period for ricin intoxication is 4-8
hours. Symptoms will depend on the dose and route
of exposure. Initial symptoms following inhala-
tion include weakness, fever, cough, dyspnea,
nausea, chest tightness, and arthralgia. Sweating,
pulmonary edema, and cyanosis usually follow.
Necrotizing, suppurative airway lesions may be
noted in conjunction with rhinitis and laryngitis.
If left untreated, respiratory failure and cardiovas-
cular collapse due to inhalation of the agent can
lead to death after 36-72 hours. Ingestion will
be followed by rapid onset of nausea, vomiting,
abdominal cramps, and severe diarrhea. Other
symptoms include fever, thirst, headache, sore
throat, and dilation of the pupils. Death may occur
on the third day or later and is usually due to
vascular collapse [5].
4.9.4 Differential Diagnosis
Q fever is not a clinically distinct illness. The
atypical pneumonia may resemble a viral illness
or pneumonia caused by
Mycoplasma pneumo-
niae
,
Legionella pneumophila
,
Chlamydia psittaci
,
and
Chlamydia pneumoniae
. All causes of rapidly
progressive pneumonia would enter the differential
diagnosis. Rapidly progressing pneumonia mimics
bacterial pneumonias due to atypical agents such as
Yersinia pestis
and
Francisella tularensis
. Endo-
carditis, hepatitis, mononucleosis, ornithosis, and
tick-borne diseases may be part of the differential
diagnosis [5].
4.9.5 Treatment
Most cases of acute Q fever will
resolve without antibiotic treatment. Tetracy-
cline, 500mg q6h po
4.10.3 Diagnosis
A diagnosis may be made by the detection of anti-
bodies via an ELISA assay. PCR may be helpful
in demonstrating the presence of toxin in environ-
mental specimens [5].
×
5-7 days or doxycycline
100mg q12h
5-7 days are the treatments of
choice. A combination of erythromycin 500mg
×
