Chlamydia pneumoniae infection has an incubation period of 3-4 weeks. Typically, there is a gradual onset, and the course is biphasic with sore throat and hoarseness preceding the cough by a week or more. Pneumonia cases resemble those caused by Mycoplasma.
CASES/YEAR
300,000 (US); 6,000,000 (Global)
OTHER NAMES
The Chlamydia family include the following species: C. trachomatis (A-C serovar = trachoma; D-K serovar = urethritis; and L1-L3 serovar = lymphogranuloma venereum), C. pneumoniae, and C. pssitaci. [Cecil p. 1977)
INCUBATION
Estimated at 3-4 weeks; [CCDM]
INITIAL SYMPTOMS
Rhinitis, cough, sore throat, hoarseness, and fever; [CCDM]
PRECAUTIONS
Standard; "Outbreaks in institutionalized populations reported, rarely." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
The most common chest x-ray findings are bilateral infiltrates. Pleural effusions are sometimes present. Cough may persist for 2-6 weeks. Chest pain is rare. Sputum is scanty. Outbreaks are common in pediatric and over-60 age groups. Daycare attendees are at increased risk for infection. Reported outbreaks in military barracks lasted up to 8 months. [CCDM, p. 481-3] Community-acquired pneumonia cases caused by C. pneumoniae: <1% to 20% in adults; Typically, there is a gradual onset, and the course is biphasic with sore throat and hoarseness preceding the cough by a week or more. [5MCC-2020] Associated conditions include otitis, sinusitis, pericarditis, myocarditis, and endocarditis. [PPID, p. 2327, 905] Primary infection: mainly school-aged children; Reinfection: adults; Pneumonia cases resemble those of Mycoplasma in lack of leukocytosis, antecedent URI (rhinitis, laryngitis, pharyngitis), nonproductive cough, and small segmental infiltrates. [Harrison ID, p. 712] Rare complications are endocarditis, erythema nodosum, Guillain-Barre syndrome, and encephalitis. [ABX Guide]
DIAGNOSTIC
Paired sera most common testing, but not routinely employed; Preferred method is PCR/molecular diagnostics (e.g., BioFire); [ABX Guide] Paired sera and PCR; [CCDM]
SIGNS & SYMPTOMS
-
>fever
-
E pharyngitis
-
E rhinitis
-
N headache
-
N lethargy
-
R chest pain
-
R cough
-
R dyspnea
-
R sputum production
-
X lung infiltrates
-
X pleural effusions
-
*ARDS
-
*encephalitis
-
*endocarditis
-
*erythema nodosum
-
*myocarditis
-
*pericarditis
-
*pneumonia
-
*pneumonitis
RISK FACTORS
- Live together in close quarters
- Work in a medical or research lab
REFERENCES FOR CASES/YEAR
1. (US) Some evidence suggest that C. pneumoniae causes up to 10% of cases of CAP; [Harrison ID, p. 712] !0% x 4 million = 400,000 (US); Estimated annual incidence = 300,000 cases/year in US; [Cecil, p. 1982]
2. (Global) US cases/yr X 20;