A 14-day-old male presents with whole-body spasms, poor suckling, and a swollen umbilical cord. What is the most likely diagnosis?

The presentation of whole-body spasms, poor suckling, and a swollen umbilical cord in a 14-day-old male strongly points towards the diagnosis of tetanus. In neonates, tetanus can occur due to the infection of the umbilical stump, often associated with inadequate hygienic practices during delivery or care. The toxins produced by the Clostridium tetani bacterium lead to muscle rigidity and spasms, which can manifest as whole-body spasms in affected infants.

In newborns, especially those with a neonatally infected umbilical cord, symptoms of tetanus may develop within the first few weeks after birth. The poor suckling could be attributed to the muscle spasms affecting all areas, including those necessary for feeding. The swollen umbilical cord suggests an infection site where the tetanus bacteria may have entered, aligning with a common presentation of neonatal tetanus.

The other options, although relevant in the neonatal period, do not fit the combination of symptoms as closely as tetanus does. Neonatal sepsis could present with poor feeding and other systemic signs but is usually not characterized by whole-body spasms specifically. Hyperbilirubinemia predominantly leads to jaundice, which may or may not affect suckling;