Q fever

Q fever, asymptomatic in up to 60% of cases, is an occupational hazard for farmers, veterinarians, and abattoir workers. Patients have a flu-like illness with headache & nonproductive cough. Some have pneumonia, hepatitis (after ingestion of contaminated milk), meningoencephalitis, & endocarditis.

CASES/YEAR
1,340 (US); 26,800 (Global)
CATEGORY
Zoonoses
AGENT TYPE
Bacteria
OTHER NAMES
Query fever; Coxiella burnettii infection;
ACUITY
Acute-Severe
INCUBATION
2-3 weeks, but may be shorter after heavy exposure; [CDC Travel]
INITIAL SYMPTOMS
Asymptomatic in up to 60% of cases; [ABX Guide] Flu-like illness with headache & nonproductive cough; Other syndromes are pneumonia, hepatitis (usually following ingestion of contaminated milk), meningoencephalitis, & endocarditis; [PPID, p. 3514]
PRECAUTIONS
Standard
COMMENTS
FINDINGS:
About 60% of cases in the USA are manifest as hepatitis. The three types of hepatitis are acute hepatitis, persistent fever associated with granulomas of the liver, and incidental hepatitis in patients with pneumonia. Pneumonia may be atypical, rapidly progressive, or incidental. Of patients with lung infiltrates by chest x-ray, only 28% have a cough. Other findings of patients with Q fever pneumonia are headache (75%), sweats (84%), myalgia (68%), nausea (49%), pleural effusions (35%), leukocytosis (33%), pleuritic chest pain (28%), diarrhea (21%), and splenomegaly (5%). Almost all patients with pneumonia have slight elevation of liver enzymes (2-3 times). Thrombocytopenia may occur. [PPID, p. 2362-6] "Unlike rickettsial diseases, acute Q fever does not cause a rash." [Merck Manual, p. 1696] A nonspecific rash occurs in 4-18% of cases. Endocarditis almost always underlies chronic Q fever. Patients with endocarditis may have hepatomegaly, splenomegaly, purpuric rash, increased gamma-globulin, renal insufficiency, stroke, and heart failure. [Harrison ID, p. 697]

COMPLICATIONS:
Chronic disease (culture negative endocarditis often without fever) may be difficult to diagnose. Rare complications are pericarditis, myocarditis (debated), meningitis, encephalitis, osteomyelitis, and chronic fatigue (debated). [ABX Guide: Coxiella burnettii] About 1% of Q fever cases are complicated by meningoencephalitis, which may be accompanied by meningismus, cranial nerve palsies, seizures, and coma. Other possible complications are osteomyelitis, hemolytic anemia, optic neuritis, and erythema nodosum. [PPID, p. 2362-6] Complications of chronic endocarditis include cerebral emboli, renal insufficiency, splenomegaly, and hepatomegaly. [Cecil, p. 2026] Coxiella burnettii can cause uveitis. [Guerrant, p. 1005]

EPIDEMIOLOGY:
Q fever is an occupational hazard for farmers, veterinarians, and abattoir workers. "Infected animals are often asymptomatic but shed massive numbers of organisms in placental tissues and birth fluids at parturition." Infectious airborne particles may be present in straw, wool, and laundry or carried downwind a kilometer or more. The case-mortality rate is <1% in untreated cases. The primary reservoirs are sheep, cattle, and goats; also cats, dogs, birds, wild mammals, and ticks. Some cases may be transmitted by raw milk from infected cows or goats. [CCDM, p. 493-7] The organism has a spore form that can survive on meat in cold storage for 1 month and in infected tissue stored in formaldehyde for 4-5 months. There are case reports of infections transmitted by handling contaminated laundry or living next to a road used by farm vehicles hauling contaminated dust and straw. Other animals that carry the infection are horses, pigs, and rabbits. [PPID, 2360-1] Person-to-person transmission has been reported (sexual, transfusion, and during delivery). A vaccine is available in Australia. [Cecil, p. 2025-6]
DIAGNOSTIC
Serology (IFA) is gold standard. Abs appear after 7-10 days of sx onset; 4X rise is diagnostic; PCR of blood most sensitive test in first 2 weeks; [ABX Guide] Clinical + Phase II IgG titer >1:128 by IFA = probable; [CDC Travel]
SCOPE
Global; May be endemic anywhere animal reservoirs are present; [CCDM] Highest prevalence in African and Middle Eastern countries; [CDC Travel]
SIGNS & SYMPTOMS
  • >arthralgia
  • >fatigue, weakness
  • >fever
  • >myalgia
  • >relative bradycardia
  • E dysphagia
  • G abdominal pain
  • G diarrhea
  • G hepatomegaly
  • G jaundice
  • G liver function test, abnormal
  • G nausea, vomiting
  • H anemia
  • H hemolysis
  • H hypergammaglobulinemia
  • H leukocytosis
  • H leukopenia
  • H lymphadenopathy
  • H splenomegaly
  • H thrombocytopenia
  • N confusion, delirium
  • N headache
  • N muscle weakness
  • N paresthesia
  • N seizure
  • N stiff neck
  • R chest pain
  • R cough
  • S lymphadenitis, acute
  • S petechiae and ecchymoses
  • S rash (exanthem)
  • U hematuria
  • X hilar lymphadenopathy
  • X lung infiltrates
  • X pleural effusions
  • *ARDS
  • *arthritis
  • *cranial neuropathy
  • *encephalitis
  • *endocarditis
  • *epididymo-orchitis
  • *erythema nodosum
  • *glomerulonephritis
  • *hepatitis
  • *meningitis
  • *myocarditis
  • *osteomyelitis
  • *pancreatitis
  • *pericarditis
  • *peripheral neuropathy
  • *pneumonia
  • *pneumonitis
  • *stupor, coma
  • *uveitis
  • *weight loss
ANTIMICROBIC

Yes

VACCINE

Yes

ENTRY
Inhalation, Ingestion, Needle (Includes Drug Abuse), Scalpel or Transfusion, Skin or Mucous Membranes (Includes Conjunctiva), Sexual Contact
SOURCE
Animal Excreta, Animal Tissue, Eating Contaminated Food, Eating Unpasteurized Milk or Cheese
RESERVOIR
Birds and Poultry, Cattle, Goats and Sheep, Cats, Deer, Elk and Antelope, Dogs, Horses, Rabbits, Rodents, Swine, Human, Wild Animals
RISK FACTORS
  • Consume unpasteurized milk/cheese
  • Handle animal carcasses or placentas
  • Handle domestic animals
  • Travel to endemic area
  • Victim--air release of infectious agents
  • Victim--water/food release
  • Work in a medical or research lab
DRUG LINK
Merck Manual: Q Fever
REFERENCES FOR CASES/YEAR
1. (US) Published in MMWR 2011 = 134; Use correction factor of 10 for reported diseases: 134 X 10 = 1340;
2. (Global) 30 cases per million in Australia and more than 4000 cases reported in the Netherlands from 2007-2010 in an outbreak from infected goats; [Harrison ID, p. 697] Cases reported in England & Wales: 56 (2008), 27 (2009), 52 (2010), 105 (2011), 115 (2012); [Public Health England website] Highest prevalence in African and Middle Eastern countries; [CDC Travel] Assumption: incidence worldwide is same as in US; Calculate: 1340 X 20 = 26800;