This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: miscellaneous, Subject name: Microbiology
A male patient came to the hospital with complaints of progressive swelling of the upper limb. On examination, the limbs are more swollen proximally than distally as shown below and is non-pitting. The skin over the swelling is thickened. What is the next best step in the management of this patient? 
Select and explain. 
A. PCR, B. X-Ray, C. Night blood test for worms, D. Lymphoscintigraphy
C: Night blood test for worms
Answer: C: Night blood test for worms 
Explanation: The given clinical picture is suggestive of lymphatic filariasis (elephantiasis). The best next step would be to test the night blood for worms since the filarial species is nocturnally periodic (between 10 pm and 4 am) in India. Lymphatic filariasis is caused by Wuchereria bancrofti and Brugia malayi. Elephantiasis is a delayed sequel to repeated lymphangitis, obstruction and lymphedema. Repeated leakage of lymph into tissues first results in lymphedema, then to elephantiasis. Treatment: Diethylcarbamazine is the drug of choice. Other options: PCR is negative in chronic filariasis. Lymphoscintigraphy is principally a research tool. X-ray is useful only if worms are calcified. Reference: Paniker&;s Textbook of Medical Parasitology 8th edition