myositis is an acute , sub - acute , or chronic inflammation of skeletal muscles .
a previously healthy 12-year - old boy was admitted to driscoll children s hospital in corpus christi , tx , usa , with a 9 day history of fever , and 7 day history of pain and weakness in the lower extremities .
three days prior to admission , he was seen by a nurse practitioner and diagnosed with otitis media and pharyngitis .
his temperature was 36.8c and the physical examination was significant for antalgic , broad - based gait and tender gastrocnemius  soleus muscles .
sensation and deep tendon reflexes were normal with absent romberg s and babinski s sign .
the white blood cell count was 8300 cells per cubic mm with 60% neutrophils and 40% lymphocytes , hemoglobin was 13.5 g / dl , and the platelet count was 172,000 cells per cubic mm .
creatinine phosphokinase ( cpk ) was elevated at 2394 /l , aspartate aminotransferase ( ast ) was 222 /l and , alanine aminotransferase ( alt ) was 143 /l .
a diagnosis of myositis was made and the patient was given analgesics and oral prednisone as dermatomyositis and polymyositis were amongst the differential diagnosis .
rhabdomyolysis was considered in the differential diagnosis and the patient was started on one and a half maintenance intravenous fluids .
our patient s clinical course was not severe and did not develop the complications usually associated with rhabdomyolysis . on day 2 of his hospital stay
, he was able to stand up with support and cpk levels came down to 1713
cerebrospinal fluid analysis showed a protein concentration of 62 mg / dl and white blood cell count of 4 .
a multiplex respiratory viral pcr was positive for rhinovirus and negative for influenza a and b , parainfluenza , metapneumovirus and adenovirus .
arboviral titers for west nile virus was negative and so was the rocky mountain spotted fever titers . on the day 3 of his hospitalization ,
serum was evaluated by use of an indirect immunofluorescence antibody ( ifa ) test kit for immunoglobulin g ( igg ) to rickettsia typhi and rickettsia rickettsii ( focus diagnostics , cypress , ca , usa ) .
the complete recovery of the patient took about 48 hours which included 100 mg of doxycycline given twice daily by mouth .
he was discharged home on doxycycline to complete a 10 day course and prednisone was discontinued .
myositis can be caused by strenuous activity , muscle trauma , illicit drug injections , genetic diseases , connective tissue disorders , diabetes and infections .
infectious myositis can involve single or multiple muscle groups in the limbs with the proximal muscles being predominantly affected the exception being trichinosis which commonly involves orbital muscles .
signs and symptoms of myositis include fever , malaise , muscle swelling , weakness and pain that is worse with movement . with this presentation ,
other diseases that should be considered are polymyositis , dermatomyositis , rhabdomyolysis , guillain barre syndrome , cellulitis , osteomyelitis , deep vein thrombosis , metabolic and other inflammatory myopathies ( table 1 ) .
rhabdomyolysis was considered as one of the top differential diagnosis for our patient and given intravenous fluids .
it presents 1 - 2 weeks after the bite of an infected flea although a history of such exposure is rarely elicited .
. the rash may not be present in 50% of the patients with murine typhus .
doxycycline is the treatment of choice , which our patient was prescribed at the time of discharge .
it has been known that murine typhus resolves even without treatment . to our knowledge , this is the first pediatric case reported of murine typhus associated with myositis and paraparesis .
physicians practicing in or near rickettsia typhi - endemic areas need to consider this in the differential diagnosis of children with evidence of myositis .
making this diagnosis may have a significant impact on the course of the disease because of the availability of antimicrobial therapy against rickettsial organism .
 a 12-year - old boy presented with fever , lower extremity pain and weakness . 
 examination revealed paraparesis , thigh and calf tenderness . 
 labs showed high creatinine phosphokinase and rickettsia typhi titers . 
 this case illustrates endemic typhus should be considered in the differential diagnosis of myositis especially in areas with high prevalence of the disease . to our knowledge , this is the first reported case of myositis and paraparesis associated with a case of murine typhus . 
Introduction
Case Report
Discussion
Conclusions