The term “Valley fever” is used pretty frequently in certain respiratory discussions and people incorrectly assume it’s a condition with a fever that you can catch from someone - that it’s a disease you can’t get rid of, and if you live “in a valley” that you can get Valley fever.
These assumptions are part truths and partly myths or exaggerations. It is true that Valley fever is an infection that can persist for a long time, longer than most other infections. Unlike tuberculosis (TB), you cannot catch it from others who have the disease. It does not typically result in serious consequences; in most cases there are no symptoms.
What is Valley fever?
Valley fever is an infection of the lungs caused by a fungus, Coccidioides
immitis. Among health care providers it is known as “cocci.” It’s a fungus that is found in arid, desert areas and therefore it’s endemic in the southwestern United States, particularly central California.
The cocci spores are very resilient can survive in the ground of desert and arid areas for many years. Winds make them airborne and move them long distances (in some cases over 100 miles). They are inhaled by a person, and the spores then morph into a different form of its lifecycle, living inside the person. Given the large vast areas of the U.S. that harbor cocci and the abundance of this fungus, it is surprising that the incidence of disease is not higher. Most recent statistics suggest that in states where Valley fever is endemic and reportable (Arizona, California, Nevada, New Mexico, and Utah), overall incidence in 2011 was 42.6 cases per 100,000 population and was highest among persons aged 60-79 years.
Valley fever in history
Valley fever has been reported as far back as the turn of the nineteenth century. It was first reported in 1892 in Argentina. However, the name of the disease comes from the San Joaquin Valley in Northern California, where the first epidemiologic and clinical investigations started in the 1930’s.
In 1994, Los Angeles experienced a large earthquake which caused massive damage and instigated an outbreak of valley fever. There were 203 cases reported, including three fatalities. These figures suggest a rate of valley fever that was roughly 10 times the normal rate, in the eight weeks following the earthquake. This was also the first report of such an outbreak following an earthquake, and it’s believed that the spores which cause the disease were carried in large clouds of dust created by seismically triggered landslides.
How does a fungal infection start?
After Inhaling the spores, they are captured by the lymphatic tissue and can live in the lymph nodes for years. In some cases, a situation occurs that limits and impairs immune function, allowing this organism to proliferate and spread. In this way, it’s not very different from tuberculosis. In other cases of cocci, there is an overwhelming inflammatory process after the inhalation of this organism that results in clinical disease.
Valley fever is not contagious by respiratory route so individuals with cocci infections do not pose a public risk.
How are cocci and tuberculosis similar?
They both cause lung infections in the upper lobes of the lungs. It is not common to have pneumonia in the upper lobe. In fact, the upper lobe is the last place where the air you breathe in goes, and it’s the last place where the air leaves when you exhale. So, the upper lobe is a place with the most stagnant air. That makes it the ideal place for an infectious agent that hides inside cells and lymphatics, like tuberculosis and cocci, to live and proliferate.
Based on this, anytime a doctor sees a pneumonic infiltrate on a chest x-ray that involves the upper lobes, the first diagnoses he considers is TB and cocci.
Although there is treatment for these conditions, the response to the medications is not as swift as with other bacterial infections. The fact that cocci resides inside the cells (limiting penetration of drugs), makes it necessary for the patient to take antifungal medications (not antibiotics) for at least six months, and sometimes for years. The most common treatment medication is called Fluconazole (Diflucan).
A tough diagnosis
A person who presents with Valley fever will typically share a story that starts with the individual living and working (or even just passing through) an endemic area in the desert. The person is commonly someone who has a job that exposes him to dust, like construction work or agricultural field work. He develops a respiratory infection or flu-like symptoms. He will typically go to a clinic and a doctor will give him a “Z-pack,” an antibiotic commonly dispensed to treat bronchitis caused by a bacterial infection. The patient will then share that there was no improvement in his symptoms. In many cases, the person often gets worse, developing fevers, chills and night sweats. These symptoms usually send the patient back to the clinic for a second visit. The doctor will then more likely suspect Valley fever and perform the blood test for the diagnosis. Results take 24 to 48 hours. If cocci is identified, the patient will be started on Fluconazole.
Cocci is diagnosed by a blood test and not by culturing the fungus. The advantage of the technique used is that it also allows the lab technician to quantify how much fungus is present. The higher the titer, the higher the burden of disease. Titer levels determine duration of treatment. The goal is to treat until the titer goes below a predetermined minimum level and stays at that level for two to three months post treatment. Additional titers will confirm success of treatment.
It’s important to note that the majority of those exposed do not develop the disease.
Valley fever treatments and complications
Estimates suggest that only a third of individuals exposed to cocci will go on to develop disease that requires treatment. Among that group, most will have uncomplicated cases and recover completely with minor symptoms persisting through the treatment phase. There are, however, some cases in which serious complications do occur – individuals with poor immune function like someone with HIV. They lack the cellular immunity necessary to contain the disease. In these cases, the infection can spread outside the lungs (disseminated cocci). These more serious cases require a second drug, Amphotericin.
One potentially serious complication is meningitis, when the fungal infection crosses into the nervous system. When a patient with cocci presents with severe headache or mental status changes it alerts the physicians to do a spinal tap to analyze the cerebrospinal fluid. This is a life-threatening situation and if the patient does survive and recover they will have to take life-long antifungal medications.
The real key in making a Valley fever diagnosis is to take a precise history from the patient, asking questions about where they live and work, or where they may have passed through, and combining that with their presenting symptoms. A bit of detective work can help to catch and properly treat this distinct condition.