CD40LG and infection: However, rapid tests such as an IgM “dot blot” can be used, such as in the case of the presented patient. Difficulties can arise due to a lack of antibodies in the acute phase of the disease, which is why in recent years, polymerase chain reaction (PCR) assays have been used to detect antibody levels in the early phase of infection [13]. The MAT method has a sensitivity of 41% within the first week, 82% during the second to fourth week, and 96% beyond the fourth week of illness.