Baylisascaris procyonis (raccoon roundworm), a parasite commonly found in raccoons (Procyon lotor), can cause severe disease in humans when it invades visceral organs or the ocular and central nervous systems. Without prompt treatment, B. procyonis infection can lead to serious complications and death. During September 2024, the Los Angeles County Department of Public Health was notified of two unrelated pediatric patients with neurologic signs and symptoms consistent with baylisascariasis, including behavioral change, lethargy, and gait instability. The first case occurred in an adolescent aged 14 years who had received a previous diagnosis of autism spectrum disorder and had a history of pica (i.e., ingestion of nonfood items); the second case occurred in a previously healthy child aged 15 months. Both were treated with albendazole and corticosteroids. The first patient returned to baseline neurologic status, but delays in diagnosis and treatment of the second patient resulted in severe neurologic sequelae. Epidemiologic investigations identified raccoon feces that had fallen from a rooftop latrine (i.e., a communal raccoon defecation site) as the possible source of exposure for the adolescent. No source of exposure was identified for the younger child. B. procyonis infection should be suspected and prompt treatment considered in patients with neurologic symptoms and cerebrospinal fluid or peripheral blood eosinophilia (>1,000 eosinophils/mL of blood), especially young children or persons with developmental disabilities or pica. In addition, the public should be aware of exposure prevention strategies, including preventing raccoon activity around properties, avoiding exposure to raccoon feces, and safely removing raccoon latrines.

INTRODUCTION: Malaria, a devastating febrile illness caused by protozoan parasites, sickened 247,000,000 people in 2021 and killed 619,000, mostly children and pregnant women in sub-Saharan Africa. A highly effective vaccine is urgently needed, especially for Plasmodium falciparum (Pf), the deadliest human malaria parasite. AREAS COVERED: Sporozoites (SPZ), the parasite stage transmitted by Anopheles mosquitoes to humans, are the only vaccine immunogen achieving > 90% efficacy against Pf infection. This review describes > 30 clinical trials of PfSPZ vaccines in the U.S.A., Europe, Africa, and Asia, based on first-hand knowledge of the trials and PubMed searches of 'sporozoites,' 'malaria,' and 'vaccines.' EXPERT OPINION: First generation (radiation-attenuated) PfSPZ vaccines are safe, well tolerated, 80-100% efficacious against homologous controlled human malaria infection (CHMI) and provide 18-19 months protection without boosting in Africa. Second generation chemo-attenuated PfSPZ are more potent, 100% efficacious against stringent heterologous (variant strain) CHMI, but require a co-administered drug, raising safety concerns. Third generation, late liver stage-arresting, replication competent (LARC), genetically-attenuated PfSPZ are expected to be both safe and highly efficacious. Overall, PfSPZ vaccines meet safety, tolerability, and efficacy requirements for protecting pregnant women and travelers, with licensure for these populations possible within five years. Protecting children and mass vaccination programs to block transmission and eliminate malaria are long-term objectives.