Pathophysiology
Cold agglutinins, or cold autoantibodies, occur naturally in nearly all individuals. These natural cold autoantibodies occur at low titers, less than 1:64 measured at 4 °C, and have no activity at higher temperatures. Pathologic cold agglutinins occur at titers over 1:1000 and react at 28-31 °C and sometimes at 37 °C. Cold agglutinin disease usually results from the production of a specific IgM antibody directed against the I/i antigens (precursors of the ABH and Lewis blood group substances) on red blood cells (RBCs). Cold agglutinins commonly have variable heavy-chain regions encoded by VH, with a distinct idiotype identified by the 9G4 rat murine monoclonal antibody. Diagnosis
Classification
AIHA can be classified as warm autoimmune hemolytic anemia  or cold autoimmune hemolytic anemia, which includes cold agglutinin disease and paroxysmal cold hemoglobinuria. These classifications are based on the characteristics of the autoantibodies involved in the pathogenesis of the disease. Each has a different underlying cause, management, and prognosis, making classification important when treating a patient with AIHA. Autoimmune hemolytic anemiaWarm-antibody typePrimary
Secondary  (lymphoproliferative disorders, autoimmune disorders) : 259 Cold-antibody type (anemia)Primary cold agglutinin disease
Secondary cold agglutinin syndromeAssociated with malignant disease
Acute, transient, infection-associated  (acute cold antibody mediated AIHA complicating Mycoplasma pneumoniae or viral infections )
Chronic (lymphoproliferative disorders) : 259 Paroxysmal cold hemoglobinuria: 259 Idiopathic
SecondaryAcute, transient (Infections other than syphilis): 259 
Chronic (syphilis): 259 Mixed cold- and warm-antibody typeIdiopathic
Secondary (lymphoproliferative disorders, autoimmune disorders) Drug-induced immune hemolytic anemia : 259 Autoimmune type
Drug absorption type
Neoantigen type

Treatment
Cold agglutinin disease may be managed successfully using protective measures (clothing) alone in most cases. Special protective clothing is sometimes necessary in extreme cases.
Spanish Minister of Health María Luisa Carcedo declared that the outbreak had expanded out of the Andalusian Autonomous Community, with one confirmed case in Extremadura and five suspected cases in Extremadura and Madrid. The Minister specified that, although new cases could appear as a consequence of the long incubation period, the contaminated product had been withdrawn. As of 21 August 2019, 132 people were diagnosed and 23 pregnant woman in hospital. On 22 August an international alert was declared. 2022 United States listeriosis outbreak
On November 9, 2022 the CDC announced that Listeria in deli meats and cheeses had been linked to at least 16 cases of listeriosis, including 13 hospitalizations and 1 death. Cases were known from Maryland, New York, Illinois, Massachusetts, New Jersey and California. See also
List of United States foodborne illness outbreaks
2008 Canadian listeriosis outbreak
2014 Macedonia listeriosis outbreak
Listeriosis in animals

References
External links
 Media related to Listeriosis at Wikimedia Commons
CDC Listeriosis site