Can Someone Get Valley Fever Again?
No, reinfection with coccidioidomycosis (valley fever) is extremely rare because initial infection produces strong, lasting immunity that protects virtually all patients from second primary infections. 1
Protection After Initial Infection
Virtually all patients who recover from coccidioidomycosis—including those with subclinical infections—are protected from second primary infections. 1 This applies to the estimated 50-67% of infections that are asymptomatic as well as symptomatic cases.
Recovery from or asymptomatic infection leads to resistance to reinfection, as documented in epidemiological studies. 2
Among 800 pregnant women in Kern County with positive coccidioidin skin tests (indicating prior infection), there were zero cases of coccidioidal dissemination during subsequent pregnancy, demonstrating the durability of immunity. 1
Reactivation vs. Reinfection: A Critical Distinction
While new infections are prevented by immunity, reactivation of latent infection can occur under specific circumstances:
Previously infected patients with severe immunosuppression can experience reactivation of latent infections requiring medical management. 1 This is fundamentally different from acquiring a new infection.
Reactivation in patients without active disease is uncommon even in high-risk situations like pregnancy. 1
Exacerbation may occur as a result of superimposed immunosuppression in those who previously recovered. 2
High-Risk Populations for Reactivation
Reactivation (not reinfection) is most likely in:
- HIV-infected patients with low CD4+ counts
- Solid organ transplant recipients on immunosuppressive therapy
- Patients on high-dose corticosteroids or TNF inhibitors 1, 3
- Pregnant women in the third trimester or immediate postpartum period (though still uncommon) 1
Clinical Implications
Patients with documented prior coccidioidomycosis who develop new pulmonary symptoms should be evaluated for reactivation rather than reinfection, particularly if immunocompromised. 1
The protective immunity from initial infection is so robust that infection "usually produces immunity to reinfection" even in endemic areas with ongoing environmental exposure. 4
Healthcare providers should focus on preventing reactivation in immunosuppressed patients rather than worrying about reinfection in immunocompetent individuals. 1