A 25-year-old female presented in the month of December with chronic fatigue, cyanosis with bluish lips and ahralgia. Peripheral blood film is shown below. What is the likely cause?

The given figure is of RBC agglutination. The history is suggestive of agglutination occurring in the month of December that is cold induced. Cold Agglutinin AIHA immune hemolytic anemia caused by IgM antibodies that bind red cells avidly at low temperatures (0deg-4degC). antibodies appear transiently following ceain infections, such as with Mycoplasma pneumoniae, EBV, CMV, influenza virus, and HIV. Clinical symptoms result from binding of IgM to red cells in vascular beds where the temperature may fall below 30degC, such as in exposed fingers, toes, and ears.