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NAME: Coccidioides spp.

SYNONYM OR CROSS REFERENCE: Coccidioides immitis, C. posadasii, Coccidioidomycosis, valley fever (San Joaquin), desert fever Footnote 1, Footnote 2.

CHARACTERISTICS: Coccidioides spp. are dimorphic fungi. In the environment they exist in a hyphal phase and release infectious arthroconidia (2 to 5 μm). Inside hosts, the arthroconidia transform into a unique structure called a spherule. The spherule is a large (120 μm), thick-walled structure containing 200-300 endospores, each of which can differentiate into a new endospore continuing the infection Footnote 1-Footnote 3.


PATHOGENICITY/TOXICITY: The majority (around 60%) of individuals infected is asymptomatic or develops a very mild illness, with symptoms including cough, fever, arthralgias, myalgias, and fatigue that can last 2-6 weeks Footnote 2-Footnote 5. Symptomatic individuals develop acute pneumonia or valley fever Footnote 2. In a small percentage of cases acute pneumonia can become chronic progressive pneumonia or pulmonary nodules and cavities can develop in the lungs, characterized by pneumonia, pleural effusion, and hilar lymphadenopathy Footnote 4, Footnote 5. Dissemination occurs in 1% of infections and can affect the skin, lymph nodes, bones, and joints, causing systemic symptoms such as fever, cough, and night sweats. Meningitis is the most serious complication of coccidioidomycosis, with symptoms including headache, nausea, vomiting, and affected mental status Footnote 4. This may occur in 30-50% of disseminated infections, and is fatal without treatment Footnote 1, Footnote 5. Coccidioidomyces infection may also lead to erythema nodosum, acute exanthema (“Toxic erythema”), erythema multiforme, Sweet’s syndrome, and interstitial granulomatous dermatitis Footnote 4.

EPIDEMIOLOGY: Coccidioides spp. are geographically limited to the alkaline soil of semiarid climates, and in regions with hot, dry summers, and low annual rainfall Footnote 2, Footnote 4. C. immitis is confined mainly to California, whereas C. posadasii occurs in the southwestern United States, northern Mexico and areas of Central and South America Footnote 3. The major risk factor for infection is environmental exposure to dust and soil Footnote 1. Disseminated infection is more common among black, Asian or Filipino individuals, pregnant women in the third trimester and immunocompromised individuals Footnote 1.

HOST RANGE: Humans, nearly all mammals, and some reptiles Footnote 6.

INFECTIOUS DOSE: Estimated to be 1-10 arthroconidia Footnote 7.

MODE OF TRANSMISSION: Inhalation of arthroconidia, although secondary transmission via fomites and organ transplants may occur Footnote 1.

INCUBATION PERIOD: 1 to 3 weeks, although some infections are asymptomatic Footnote 1.

COMMUNICABILITY: Not contagious but has occasionally been transmitted from person-to-person via fomites or organ transplants Footnote 1.


RESERVOIR: Soil in southwestern US, parts of Central and South America Footnote 1.

ZOONOSIS: None Footnote 8. Although there is zoonotic potential, no reports of transmission between animals and humans have been documented Footnote 9.



DRUG SUSCEPTIBILITY: Susceptible to amphotericin B and the azole group of antifungal drugs particularly the second generation congeners (itraconazole and voriconazole) Footnote 2, Footnote 3.

DRUG RESISTANCE: Resistance has been observed against azoles Footnote 10. This area remains a growing concern when repeated doses are administered, especially in endemic areas.

SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to 1:10 dilution of bleach, ≥6% hydrogen peroxide, 8% formaldehyde or 3% phenolics with a contact time of 20 minutes or more Footnote 7.

PHYSICAL INACTIVATION: Fungi in soil can be inactivated by heat at 120 ºC for 30 minutes Footnote 11.

SURVIVAL OUTSIDE HOST: Coccidioidal arthroconidia are hardy and can survive for long periods of time on inanimate surfaces Footnote 7. They can grow in the soil in semiarid climates Footnote 2.


SURVEILLANCE: Monitor for symptoms. Diagnosis of coccidioidomycosis can be established using serologic, histopathologic and culture methods Footnote 2, Footnote 3. Skin tests can be used to identify the disease Footnote 2.

Note: All diagnostic methods are not necessarily available in all countries.

FIRST AID TREATMENT: Coccidioidomycosis is generally self-limiting and will resolve without treatment. Disseminated infections, or patients who experience excessive morbidity, should be treated with antifungal medication. The type of drug and length of treatment depends on the site of infection and clinical response Footnote 2, Footnote 3, Footnote 5.


PROPHYLAXIS: Exposed personnel should be given itraconazole or fluconazole (400 mg daily for 6 weeks Footnote 7.


LABORATORY-ACQUIRED INFECTIONS: 93 cases of laboratory-acquired coccidioidomycosis infections and two deaths were reported prior to 1978 Footnote 12. An additional 15 cases were asymptomatic but identified with skin tests during that period Footnote 13. One symptomatic case has been reported from 1979-2004 Footnote 14.

SOURCES / SPECIMENS: Lower respiratory tract samples, cerebrospinal fluid, sputum, skin and visceral lesions, and soil samples from infected areas (southwestern United States, parts of Central and South America) Footnote 1, Footnote 2.

PRIMARY HAZARD: Inhalation of spores, parenteral inoculation or contact with mucous membranes Footnote 15, Footnote 16.



RISK GROUP CLASSIFICATION: Risk group 3 Footnote 17. This risk group applies to the genus as a whole, and may not apply to every species within the genus.

CONTAINMENT REQUIREMENTS: Containment Level 3 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures.

PROTECTIVE CLOTHING: Personnel entering the laboratory should remove street clothing and jewellery, and change into dedicated laboratory clothing and shoes, or don full coverage protective clothing (i.e., completely covering all street clothing). Additional protection may be worn over laboratory clothing when infectious materials are directly handled, such as solid-front gowns with tight fitting wrists, gloves, and respiratory protection. Eye protection must be used where there is a known or potential risk of exposure to splashes Footnote 18.

OTHER PRECAUTIONS: All activities with infectious material should be conducted in a biological safety cabinet (BSC) or other appropriate primary containment device in combination with personal protective equipment. Centrifugation of infected materials must be carried out in closed containers placed in sealed safety cups, or in rotors that are loaded or unloaded in a biological safety cabinet. The use of needles, syringes, and other sharp objects should be strictly limited. Open wounds, cuts, scratches, and grazes should be covered with waterproof dressings. Additional precautions should be considered with work involving animals or large scale activities Footnote 18.


SPILLS: Allow aerosols to settle, then, wearing protective clothing, gently cover the spill with absorbent paper towel and apply appropriate disinfectant, starting at the perimeter and working towards the center. Allow sufficient contact time before starting the clean up Footnote 18.

DISPOSAL: All wastes should be decontaminated before disposal either by steam sterilization, incineration or chemical disinfection Footnote 18.

STORAGE: The infectious agent should be stored in a sealed and identified container Footnote 18.


REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.

UPDATED: November 2010

PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada

Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.

Copyright ©
Public Health Agency of Canada, 2010


Footnote 1
Brandt, M. E., & Warnock, D. W. (2007). Histoplasma, Blastomyces, Coccidioides, and Other Dimorphic Fungi Causing Systemic Mycoses. In P. R. Murray, E. J. Baron, J. H. Jorgensen, M. L. Landry & M. A. Pfaller (Eds.), Manual of Clinical Microbiology (9th ed., pp. 1857-1873). Washington, D.C.: ASM Press.
Footnote 2
Ryan, K. J. (2004). Cryptococcus, Histoplasma, Coccidioides, and other Systemic Fungal Pathogens. In K. J. Ryan, & C. G. Ray (Eds.), Sherris Medical Microbiology: An Introduction to Infectious Diseases (4th ed., pp. 678-683). New York: McGraw-Hill.
Footnote 3
American Academy of Pediatrics.Committee on Infectious Diseases. (2009). Red book (28th ed.). Elk Grove Village, IL: American Academy of Pediatrics. Retrieved from STAT!Ref
Footnote 4
DiCaudo, D. J. (2006). Coccidioidomycosis: a review and update. Journal of the American Academy of Dermatology, 55(6), 929-42; quiz 943-5. doi:10.1016/j.jaad.2006.04.039
Footnote 5
Parish, J. M., & Blair, J. E. (2008). Coccidioidomycosis. Mayo Clinic Proceedings, 83(3), 343-349.
Footnote 6
Shubitz, L. F. (2007). Comparative aspects of coccidioidomycosis in animals and humans. Annals of the New York Academy of Sciences, 1111, 395-403.
Footnote 7
Stevens, D. A., Demons, K. V., Levine, H. B., Pappagianis, D., Baron, E. J., Hamilton, J. R., Deresinski, S. C., & Johnson, N. (2009). Expert opinion: What to do when there is coccidioides exposure in a laboratory. Clinical Infectious Diseases, 49(6), 919-923.
Footnote 8
Krauss, H., Weber, A., Appel, M., Enders, B., Isenberg, H. D., Sheifer, H. S., Slenczka, W., von Graevenitz, A., & Zahner, H. (2003). Fungal Zoonoses. Zoonoses: Infectious Diseases Transmissible from Animals to Humans (3rd ed., pp. 253-259). Washington D.C.: ASM Press.
Footnote 9
Haskell, S. R. R. (2008). Blackwell's Five-Minute Veterinary Consult: Ruminant Wiley-Blackwell.
Footnote 10
Kriesel, J. D., Sutton, D. A., Schulman, S., Fothergill, A. W., & Rinaldi, M. G. (2008). Persistent pulmonary infection with an azole-resistant Coccidioides species. Medical Mycology : Official Publication of the International Society for Human and Animal Mycology, 46(6), 607-610. doi:10.1080/13693780802140923
Footnote 11
Dunn, P. H., Barro, S. C., & Poth, M. (1985). SOIL MOISTURE AFFECTS SURVIVAL OF MICROORGANISMS IN HEATED CHAPARRAL SOIL. Soil Biol. Biochem, 17, 143-148.
Footnote 12
Pike, R. M. (1976). Laboratory associated infections: summary and analysis of 3921 cases. Health Laboratory Science, 13(2), 105-114.
Footnote 13
Collins, C. H., & Kennedy, D. A. (1999). Laboratory acquired infections. Laboratory acquired infections: History, incidence, causes and prevention (4th ed., pp. 1-37). Woburn, MA: BH.
Footnote 14
Harding, A. L., & Byers, K. B. (2006). Epidemiology of Laboratory-Associated Infections. In D. O. Fleming, & D. L. Hunt (Eds.), Biological Safety: Principles and Practices (4th ed., pp. 64). Washington, D. C.: ASM Press.
Footnote 15
Balows, A. (1998). Safety in Microbiology Laboratory. In L. Collier, A. Balows, M. Sussman & B. I. Duerden (Eds.), Micriobiology and Microbiological infections, Volume 2, Systametic Bacteriology. (9th ed., pp. 438-441). NY, USA: Aronold press.
Footnote 16
Schell, W. A. (2006). Mycotic Agent of Human Disease. In D. O. Fleming, & D. L. Hunt (Eds.), Biological Safety, Principles and Practices (4th ed., pp. 163-178). Washington, D.C.: ASM Press.
Footnote 17
Human Pathogens and Toxins Act. S.C. 2009, c. 24. Government of Canada, Second Session, Fortieth Parliament, 57-58 Elizabeth II, 2009, (2009).
Footnote 18
Public Health Agency of Canada. (2004). In Best M., Graham M. L., Leitner R., Ouellette M. and Ugwu K. (Eds.), Laboratory Biosafety Guidelines (3rd ed.). Canada: Public Health Agency of Canada.