Patients typically have lymphopenia, thrombocytopenia, elevated creatinine, and elevated liver transaminases. Diagnosis can be accomplished by a viral culture of blood in the first three days; however, chikungunya is a biosafety level-3 (BSL-3) pathogen. RT-PCR in the first week and IgM antibodies after the first four days can be positive in serum or plasma. Serological tests may not be positive until after the first week of illness. Confirmation is by acute and convalescent plaque reduction neutralization test (PRNT) for IgG antibodies, which is required because antibodies to other mosquito-borne diseases cross-react with the chikungunya virus. Most testing is performed in public health laboratories or referred to the CDC; some commercial laboratories may offer appropriate testing algorithms.
