Understanding 5 Key Infectious Diseases: Symptoms, Diagnosis, and Treatment
Tetanus
Probable Diagnosis
Tetanus, caused by Clostridium tetani.
Pathogenesis and Clinical Manifestations
Pathogenesis
- Clostridium tetani spores enter through wounds and germinate in anaerobic conditions.
- The bacteria produce tetanospasmin, a toxin that blocks the release of inhibitory neurotransmitters (GABA and glycine) in the spinal cord, causing uncontrolled muscle contractions (spastic paralysis).
Clinical Manifestations
Early Signs
Trismus (lockjaw), neck stiffness, and difficulty swallowing.
Generalized Tetanus
- Muscle spasms (e.g., back arching – opisthotonus, facial spasm – risus sardonicus).
- Difficulty breathing due to diaphragm spasms.
- Autonomic symptoms: Sweating, rapid heart rate, and high blood pressure.
- Complications: Respiratory failure, fractures, and death.
Laboratory Diagnosis
- Clinical diagnosis: Based on symptoms.
- Microscopy: Gram-positive bacilli with terminal spores (drumstick appearance).
- Culture: Grows anaerobically on media like Robertson’s cooked meat medium.
Vaccination
- Primary immunization: DTaP vaccine at 6, 10, and 14 weeks of age, with boosters at 16-24 months, 4-6 years, and 10-16 years.
- Adults: Booster every 10 years (Td vaccine).
- Post-exposure prophylaxis:
- Clean the wound.
- Give Tetanus Toxoid (TT) and Tetanus Immunoglobulin (TIG) if vaccination history is incomplete or unknown.
- Maternal vaccination: Prevents neonatal tetanus.
Vaccine-Associated Paralytic Poliomyelitis (VAPP)
Probable Diagnosis
Vaccine-Associated Paralytic Poliomyelitis (VAPP) caused by the oral polio vaccine (OPV) strain.
Pathogenesis and Clinical Features
Pathogenesis
OPV contains live attenuated poliovirus. Rarely, it can revert to a virulent form and cause paralysis, especially in individuals with an immature immune system.
The virus infects and damages anterior horn cells in the spinal cord, leading to lower motor neuron paralysis.
Clinical Features
- Flaccid paralysis: Sudden weakness in one limb (asymmetric).
- Loss of reflexes: No deep tendon reflexes in the affected limb.
- Sensation intact: Sensory nerves remain unaffected.
- CSF: Elevated protein with normal glucose.
Laboratory Diagnosis
- Stool sample: Isolation of poliovirus by viral culture.
- RT-PCR: Differentiates wild-type from vaccine-derived strains.
- CSF analysis: Elevated protein with normal glucose.
Types of Vaccines
- Oral Polio Vaccine (OPV)
- Live attenuated vaccine given orally.
- Effective, but can rarely cause VAPP.
- Inactivated Polio Vaccine (IPV):
- Killed virus vaccine given via injection.
- Safe and does not cause VAPP.
Current Strategy: IPV is included in the immunization schedule to reduce VAPP risk while maintaining OPV use in eradication programs.
Rabies Virus
Probable Etiological Diagnosis
Rabies, caused by the Rabies virus.
Labeled Diagram
