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Coccidioidomycosis Fungal Infection (Valley Fever)


Coccidioidomycosis Fungal Infection (Valley Fever) overview and Definition

Valley fever is an infection caused by the Fungus Coccidioidomycosis. It gets entry into the body through lungs. It is also known as desert rheumatism.


Pathophysiology

The coccidioidomycosis is primarily transmitted via respiratory inhalationa of the airborne arthoconidia. Once inhales the fungus coccididiodes are deposited into terminal bronchioles and enlarge to form spherules. Spherules are then filled with thousand  of endospores. The spherules later rupture releasing new endospores and propagating the fungal life to the next stage. Dissemination of the infection occurs through passage within the lymphatics to extrapulmonary sites or haemotogeneous spread to the bone, brain, skin.

Rarely this coccidioidal infection can occur from direct inoculation following penetrating trauma, resulting in localized, cutaneous and soft tissue infections. All people travelling or residing to endemic regions are at higher risk of arthroconidia.

Sometimes these might leads to acute respiratory distress syndrome


Routes of Transmission

The main route by which the fungus spread is by inhalation of the spores.

Sometimes the spore might also get spread by breakage in the skin or open wounds.

 

 


Clinical signs & symptoms

Pneumonia with severe and life threatening complications including disseminated infection.

The predominant symptoms of primary coccidioidal pneumonia include cough,fever and pleuritic chest pain. Differentiation from community acquired pneumonia in primary infection.

Pleural effusions can occur in small proportion of patient.

Empyema

Intrathoracic lymphadenopathy

Pulmonary parenchyma to the lymphatic system

Cough

Fever

Pleuritic chest pain

Hilar or mediastinal nodes enlarged

Skin rash

Peripheral eosinophilia

The desert rheumatism includes the combination of the joint pain, erythema nodosum, fever.

In chronic conditions the involvement might result in damage to the vital organs. Dissemination of the infection might leads to the brain, soft tissue, joints and bones.

Osteomyelitis (necrosis of the bone due to the blood supply to the bone marrow is cut off. It is termed as inflammation of the bone and bone marrow)

Complications:

Severe pneumonia with respiratory failure

Brochopleural fistulas

Skin ulcers

Abscesses

Bone lesions

Swollen joints with severe pain

Urinary tract problems

Inflammation surrounding the brain lining

Inflammation of the heart


Differential Diagnosis

Staining:

The organisms can be isolate from sputum, skin lesions, CSF and pleural fluid.

It requires special media for growth and it can be recognized after 3-5 days after inoculation onto the routine media.

Spherules  can be best identified with acids. And the size of the spherules might differ from 20-80 micronmeter in diameter. They are best identified under Schiff or Gomori methamine silver stains. This reaction often reults in granulomatous reactions with fibrosisand caseation in chronic lesions.

Immunodiffusion methods:

It is based on the immunoprecipitation reaction.

In general, in mixed antigen—antibody reactions, each antigen—antibody combination will form a separate line of precipitation, distinct from those of other antigen—antibody interactions.

Immunodiffusion and enzyme immunoassay:

It is used to detect the presence of IgG and IgM antibodies. A coccidioidal antigen assay is available which may sense positive in the urine and blood of patients with extrapulmonary disease and in the CSF of those with meningitis caused by C. immitis. If a patient has typical clinical manifestations of C. immitis, then the EIA IgM positive/IDCF negative result supports the presence of disease.

Beta D Glucan:

An antigen compound which is useful in the diagnosis of valley fever.

Chest Xray:

The chest x ray predicts any abnormal area in the lungs

Computed tomography:

It reveals the slice of the lung. It uses both the combination of x ray and computer aided device.

It helps to analyse the size, shape and position of any lung tumour and also it helps in the detection of enlarged lymph nodes.

It also looks for any masses in the adrenal gland, liver, brain and other organs.

 CT guided needle Biopsy:

CT scan might be used to guide a biopsy needle into this  area to get the tissue for lung structure.

MRI scan:

It uses the soft tissue image of the organ. It uses the both the magnet and radiowaves.

It reveals abnormality in the lung tissue and lymph node enlargement.

 


Prognosis

Prognosis is good when the treatment is started at an earlier stage. 90% of cure rate we can expect at earlier stages.


Prevention

Prevention of coccididiomycosis:

  • Try to avoid areas with a lot of dust like construction or excavation sites. If you can’t avoid these areas, wear an N95 respirator (a type of face mask) while you’re there.
     
  • Stay inside during dust storms and close your windows.
  • Avoid activities that involve close contact to dirt or dust, including yard work, gardening, and digging.
  • Use air filtration measures indoors. Or HEPA filters indoors.
  • Clean skin injuries well with soap and water to reduce the chances of developing a skin infection, especially if the wound was exposed to dirt or dust.
  • Take preventive antifungal medication if your healthcare provider says you need it.


Reference

https://www.cdc.gov/fungal/diseases/coccidioidomycosis/risk-prevention.html

https://my.clevelandclinic.org/health/diseases/17754-valley-fever-coccidioidomycosis

https://www.mayoclinic.org/diseases-conditions/valley-fever/symptoms-causes/syc-20378761

https://www.uptodate.com/contents/coccidioidomycosis-in-immunocompromised-and-pregnant-persons