What Is Valley Fever (Coccidioidomycosis)? What Causes Valley Fever?
Valley fever, also known as coccidioidomycosis, California disease, Desert rheumatism, and San Joaquin valley fever is a fungal disease that is endemic in certain parts of Arizona, New Mexico, Texas, Utah, Nevada and northwestern Mexico. It is caused by Coccidioides immitis or C. posadasii. Infected individuals experience fever, chest pain, coughing and some other symptoms.
Coccidioides immitis is a pathogenic fungus that resides in the soil. During long, dry spells the fungus remains dormant, and then develops as a mold with elongated filaments which break off and become airborne spores, known as arthroconidia, during the rainy season. The arthroconidia become airborne after disruption of the soil from farming, earthquakes, wind or construction activity.
Humans become infected by inhaling the fungus particles. Valley fever is not a human-to-human transmissible disease - you cannot catch it from an infected person.
Individuals with mild cases of valley fever do not usually require medical therapy, as the condition resolves on its own. However, in more severe cases the patient may need antifungal medications.
According to the CDC (Centers for Disease Control and Prevention), USA, approximately 50,000 to 100,000 people are estimated to develop valley fever symptoms each year in the USA, with 35,000 new infections annually just in California. According to health authorities in Arizona, the incidence of reported cases was 15 per 100,000 in 1995.
According to Medilexicon's medical dictionary:
Coccidioidomycosis is A variable, benign, severe, or sometimes fatal systemic mycosis due to inhalation of arthroconidia of Coccidioides immitis. In benign forms of the infection, the lesions are limited to the upper respiratory tract, lungs, and near lymph nodes; in a low percentage of cases, the disease disseminates to other visceral organs, meninges, bones, joints, skin, and subcutaneous tissues.
What are the signs and symptoms of valley fever?A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.
Acute valley fever (acute coccidioidomycosis) - initially symptoms are generally mild. Some infected individuals have no symptoms at all, and only know they were infected when they test positive for a skin or blood test. According to the University of Arizona, it is believed that more than 60% of infected people have either no symptoms or experience flu-like symptoms and never seek medical attention. Signs and symptoms, if they do appear, do so approximately 1 to 3 weeks after exposure, and may include:
- Chest pain - may be mild or quite severe
- Joint aches
- Muscle aches
- Night sweats
- Shortness of breath
- Skin rash - generally, consisting of spotty red bumps on the lower legs, which may be painful; eventually they become brown (erythema nodosum). The rash may also appear on the back, arms or chest. More rarely, the rash may produce blisters.
Patients with severe symptoms may take up to a year to recover completely - with fatigue and joint pains perhaps persisting for longer.
Chronic valley fever (chronic coccidioidomycosis) - if the patient with acute valley fever does not make a full recovery, the condition might progress to a chronic (long-term) form of pneumonia. This is rare, and individuals with weakened immune systems are more susceptible. Patients with chronic valley fever typically experience fluctuations in symptom severity. Signs and symptoms may include:
- Slight fever
- Weight loss
- Chest pains
- Blood stained spit (sputum)
- Lung nodules
- 15-20% of people develop skin lesions.
- Skull lesions, which are often painful.
- There may also be lesions in the spine, and perhaps some other bones.
- Swollen joints, which are usually painful.
- Meningitis - The membranes that surround the brain and the spinal cord are collectively known as the meningess - meningitis means inflammation of the meninges.
- Muscle stiffness.
- Muscle aches.
- Neck or shoulder stiffness.
- Change in mental status.
- Photophobia - sensitivity to light.
What are the risk factors for valley fever?A risk factor is something which increases the likelihood of developing a condition or disease. For example, obesity significantly raises the risk of developing diabetes type 2. Therefore, obesity is a risk factor for diabetes type 2.
Geographical location - anybody who is in an area where fungus spores are likely to be, such as Arizona, New Mexico, Texas, Utah, Nevada and northwestern Mexico, is at risk of inhaling them in and becoming infected. Especially people working in some occupations, such as construction, excavation, agricultural work, archaeological digging - occupations which disturb soil in endemic areas.
Race - according to The Mayo Clinic, Filipinos, Hispanic Amerindians, Native North Americans and Asians have a higher risk of developing infections with symptoms, compared to Caucasians.
Being pregnant - during the third trimester of a pregnancy, and right after the baby is born, mothers are more likely to become infected (in endemic areas).
Having diabetes - individuals with diabetes who live in areas where valley fever exists have a higher risk of becoming infected, compared to other people in the same areas.
Weak immune system - people whose immune system is weakened have a higher risk of infection and complications, such as patients with HIV/AIDS, people taking steroid medications, chemotherapy or immunosuppressant drugs. People with cancer may also be more susceptible.
Being elderly - seniors are more likely to develop valley fever, compared to younger individuals.
What are the causes of valley fever?Valley fever is caused mainly by Coccidioides immitis, and partly by Coccidioides posadasii. The fungus spores than can be inhaled when they get into the air. Spores are tough forms of the fungus that can survive for very long periods in harsh conditions, such as droughts, heat, or cold.
Coccidioides immitis and Coccidioides posadasii exist in alkaline desert soils, such as those found in northwestern Mexico, California's San Joaquin Valley, Nevada, New Mexico, Texas and Arizona. Valley fever also exists in some parts of South and Central America.
The fungus, which grows into a mold, develops long filaments which break off and float in the air (wind) - they become airborne. People breathe in the spores and become infected.
How is valley fever diagnosed?A doctor cannot diagnose valley fever just by identifying the signs and symptoms, which are present in other illnesses, such as flu. X-rays of the lungs cannot distinguish the disease from other diseases or conditions either.
If the doctor suspects valley fever ,some diagnostic tests will be ordered which can detect the present of Coccidioides spherules (cysts) in blood, tissue or saliva (sputum). The following tests will probably be ordered:
- Sputum smear test - a sample of sputum is taken and tested for the presence of coccidioides (sputum is what we cough up from the lungs, trachea or bronchi).
- Blood test - these will detect antibodies against the fungus.
What are the treatment options for valley fever?The majority of infected people do not need treatment. Even in more severe cases, doctors say the best treatment is plenty of rest, and to consume a lot of liquids; as one would do with a flu or cold. Even so, the patient should be carefully monitored.
Antifungal medications - these may be prescribed if:
- The patient's symptoms persist
- The patient has a higher risk of complications, as may be the case if the individual has a weakened immune system
- The patient has chronic valley fever or disseminated disease
- Abdominal pain
Although these medications control the fungus, they do not eliminate it - so, there is still a risk of relapses.
What are the possible complications of valley fever?Complications are very rare; the risk is slightly higher for the higher risk groups (see Risk Factors section). If complications do occur, they may include:
- Pneumonia - often severe pneumonia. An infection of the lungs, characterized primarily by inflammation of the alveoli in the lungs or by alveoli that are filled with fluid (alveoli are microscopic sacs in the lungs that absorb oxygen).
- Ruptured lung nodules - some patients develop cavities (nodules) in their lungs. Most of them go away. However, sometimes they may rupture, resulting in severe chest pain and breathing difficulties. The patient may need a tube inserted into the space around the lungs to remove the air. Sometimes surgery is required.
- Disseminated disease - the fungus spreads through the bloodstream to various parts of the body, affecting many organs. This is the most serious complication. The patient can develop skin ulcers, bone lesions, abscesses, severe joint pain, inflammation of the heart, problems with the urinary tract, and meningitis.