Infectious Diseases Overview Quiz

BCG

• BCG has been used as an adjunctive therapy for malignancies, like bladder carcinoma.
• A recombinant BCG vaccine is under phase II trial (2017).
• Its immunogenicity is improved by replacing the urease C gene.
• It promotes phagolysosome fusion.

Chemoprophylaxis

• Treatment of high-risk tuberculin reactors aims to prevent active tuberculosis.
• Isoniazid or ethambutol for 6 months have been tried.

COVID-19

• Originated in China and spread rapidly worldwide.
• Affected almost every part of the world, causing significant fatalities and a global financial crisis.
• Average mortality rate is estimated to be 2.2%.
• China saw a rapid rise in cases, with Wuhan accounting for > 80% of the cases.
• Cases rapidly declined in China after the initial surge.
• Italy experienced high mortality rate (> 10%) due to a lack of preparedness.
• The USA has the highest reported cases (>3 crore) with a mortality rate of 1.8%.

Enterococcus and other Streptococci

• They cause infections in various body sites, making them relevant in discussions pertaining to different infective syndromes.
• Enterococcus is non or -hemolytic, found as normal flora in the human intestine.
• It causes various infections like UTI, meningitis, intra-abdominal infections, and endocarditis.
• Viridans streptococci are α-hemolytic, found as normal flora in the oral cavity.
• They are responsible for dental caries and endocarditis.
• Streptococcus pneumoniae is α-hemolytic.
• It primarily causes pneumonia and can spread to cause bacteremia and meningitis.
• It is also recognized as a cause of local infections like otitis media and sinusitis.

Group F Streptococci

• Also known as minute streptococci.
• They grow poorly on blood agar and can occasionally cause suppurative infections.

E.granulosus

• The laboratory diagnosis and treatment are similar to that of E. multilocularis.

Liver Flukes

• Fasciola, Clonorchis, and Opisthorchis are collectively known as liver flukes.
• Fasciola infects the liver and bile duct, while the others infect only the bile duct.

Liver Flukes Life Cycle

• It is similar to other trematodes, excluding schistosomes.

Liver Flukes Laboratory Diagnosis

• Stool microscopy identifies characteristic operculated eggs (130–150 μm × 63–90 μm).
• Concentration techniques, like sedimentation methods, are used to increase sensitivity.
• Floatation methods are not effective.
• Eggs of Fasciola hepatica resemble those of Fasciolopsis buski.
• Antibody detection through ELISA or western blot detects serum antibodies against excretion secretion antigen.
• This helps in early diagnosis before eggs appear in stool, facilitating seroepidemiological studies and monitoring treatment response.

Cerebral Malaria

• Artesunate, artemether, arteether, and quinine are the drugs used for treatment.

African Sleeping Sickness

• Caused by Trypanosoma brucei (T.b.) gambiense and T.b. rhodesiense, responsible for Western and Eastern African sleeping sickness, respectively.
• Transmitted by tsetse flies, injecting metacyclic trypomastigotes.

African Sleeping Sickness Pathogenesis

• Begins with the hemolymphatic stage.
• Clinical features include:
  • Increased intracranial pressure and hypertension manifesting as headache, vomiting, and vertigo.
  • Chronic meningitis.
  • Focal neurological deficits.
  • Psychological disorders and dementia.
  • Cerebral arteritis associated with subarachnoid cysticercosis.
  • Basal and ventricular involvement carries a poor prognosis.

NCC (Neurocysticercosis)

• Occurs in four morphological stages: vesicular, necrotic, nodular, and calcified.
• Clinical presentation varies based on:
  • Number, location, and size of the cyst.
  • Morphological stage of the cyst.
  • Host immune response.
• NCC co-infection is increasingly recognized in HIV patients and should be considered.

NCC Clinical Features

• Increased intracranial pressure and hypertension.
• Headache, vomiting, and vertigo.
• Chronic meningitis.
• Focal neurological deficits.
• Psychological disorders and dementia.
• Cerebral arteritis (associated with subarachnoid cysticercosis).
• Basal and ventricular involvement: Carries poor prognosis.

NCC Laboratory Diagnosis

• Radiodiagnosis (Imaging Methods):
  • CT scan and MRI are crucial for detecting cysticerci in the brain.
• Antibody detection in serum or CSF:
  • ELISA using crude extract of cysticerci.
  • Western blot using 13 kDa LLGP Ag.
• Antigen detection in serum or CSF: ELISA.
• Lymphocyte transformation test.
• Histopathology of muscles, eyes, subcutaneous tissues, or brain biopsies: Can detect cysticerci.
• FNAC of the cyst followed by Giemsa staining.
• Fundoscopy of the eye can detect larvae.
• Modified Del Brutto diagnostic criteria.

Cysticercosis

• Autoinfection:
  • External: Due to unhygienic practices, such as contaminated fingers.
  • Internal: Due to reverse peristaltic movements where gravid segments release eggs back into the stomach.
• Autoinfection carries a bad prognosis.