Tests
1st tests to order
CBC with differential
Test
Should be ordered routinely in febrile patients. Patients may develop leukopenia, lymphopenia, or thrombocytopenia. However, results are usually nonspecific. Prominent leukocytosis, neutrophilia, and bandemia may suggest an alternate, nonviral etiology.[49][50]
Result
leukopenia, lymphopenia, thrombocytopenia
LFTs
erythrocyte sedimentation rate
Test
An elective test that correlates with the degree of the inflammatory response.
Result
elevated
CRP
Test
An elective test that correlates with the degree of the inflammatory response.
Result
elevated
basic metabolic panel
serology
Test
Indirect immunofluorescence or enzyme-linked immunosorbent assay for detection of IgM or IgG antibodies is the most common and least expensive way to confirm the diagnosis.
A single positive result for IgM antibody confirms the diagnosis. IgM is usually detected 5 to 6 days after the starting of symptoms and can last for 3 to 4 months. A positive IgM antibody result should be confirmed by neutralizing antibody testing.[47] IgG requires a fourfold titer elevation between baseline testing and convalescent readings at least 2 weeks later. IgG is usually detected after the first week of disease and remains positive for years. It is important not to check antibodies too early in the course of the disease, as the results may be false negative.[56]
Result
detection of chikungunya virus antibodies
molecular testing
Test
Available molecular tests include real-time reverse transcription polymerase chain reaction (RT-PCR), real-time loop-mediated isothermal amplification (RT-LAMP), and conventional RT-PCR assay. The advantage of these methods includes high sensitivity and specificity and earlier diagnosis (it can be positive as soon as the clinical picture becomes apparent, as patients are highly viremic by then). The disadvantages include the cost, lesser availability of the required equipment, and, at least for the real-time RT-PCR, the intense labor required.[56]
In the US, the Food and Drug Administration has issued an Emergency Use Authorization for the Trioplex RT-PCR assay. The assay allows physicians to determine whether a patient is infected with chikungunya, Zika, or dengue virus in one test rather than having to order 3 separate tests, allowing for more rapid diagnosis.[55] Availability of commercial tests depends on location; it is only available in qualified laboratories and is not available in US hospitals or other primary care settings. CDC: revised diagnostic testing for Zika, chikungunya, and dengue viruses in US Public Health Laboratories Opens in new window
Result
detection of chikungunya virus genetic material
Tests to consider
musculoskeletal imaging
Test
Rheumatologic radiologic imaging during the acute phase of illness does not contribute to the diagnosis, except maybe to rule out other conditions. Imaging may be indicated in patients with chronic arthritis.
CT or MRI may be of particular help in cases of monoarthritis.
Result
plain articular x-rays may show bony erosions and marrow edema - the destructive changes resemble rheumatoid arthritis; CT scan or MRI may provide additional details of joint involvement including presence of tendinitis and joint effusions, or help to exclude osteomyelitis or septic arthritis
MRI brain
Test
Recommended in patients with suspected meningitis or meningoencephalitis.
Result
hyperintensity in the temporal lobes and insular cortex or periventricular enhancement (encephalitis); meningeal enhancement (meningitis); multiple hyperintense lesions in T2 and fluid-attenuated inversion recovery (FLAIR; acute demyelinating encephalomyelitis)
cerebrospinal fluid analysis
Test
Recommended in patients with suspected meningitis or meningoencephalitis.
Result
typical findings of aseptic compromise of the meninges, including mild pleocytosis with predominance of mononuclear cells, elevated protein and normal to mildly low glucose
electromyogram
Test
Indicated in cases of weakness or lower extremities paresias, particularly if associated with hyporeflexia.[66]
Result
generalized motor axonal neuropathy in cases of myeloradiculitis
nerve conduction studies
Test
Indicated in cases of weakness or lower extremities paresias, particularly if associated with hyporeflexia.[66]
Result
generalized motor axonal neuropathy in cases of myeloradiculitis
electroencephalogram
Test
Indicated when encephalitis is suspected.[66]
Result
diffuse slowing of electrical activity in cases of encephalitis
placental histology
Test
Placental histologic examination performed on the placenta of an infected mother; however, this is not routinely done, as diagnosis in both mother and newborn can done via serology. It may be considered in the settings of low-weight newborns, congenital abnormalities, or stillbirths.
Result
histologic signs compatible with placental infection
Emerging tests
viral culture or mice inoculation
Test
Viral isolation by inoculation in mice or by inoculation in mosquito or mammalian cell lines (including HeLa and Vero cells) are not used in clinical practice. They require biosafety level 3 laboratories and results are not available as promptly as with other methods.[56]
Result
positive viral culture
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