If this was done through a standard lab instead of a lab that specializes in tick-borne illness testing, then it would be best if your cousin could be re-tested through IGeneX or another Lyme-literate lab (MDL, Clongen, etc.).
Also, one must interpret the lyme test results in the context of symptoms, being ever aware that the tests are often negative when in fact the person does have Lyme - hence why even the CDC/IDSA say that Lyme should be a clinical diagnosis (i.e., based on clinical presentation of symptoms and not based solely on test results).
An LLMD may offer more insights for interpretation of these test results, also... Good luck,
Chronic Lyme Disease, Chronic Bartonella (clinical dx only), Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication/Chemical Allergies & Intolerances, Asthma, Gut issues (dysmotility, non-specific inflammation), UCTD ("Secondary Lupus-Like Syndrome"), Osteoporosis, chronic Lymphopenia, etc.; G-Tube; Currently weaning off TPN.
Meds: Pulmicort, IV Doxycycline, Heparin (to flush PICC line), Claritin, Singulair, Domperidone, Colloidal Silver (topically & nasally), probiotics, Liver support herbs, Ailanthus, digestive enzymes, homeopathy.