Diseases: Malaria and Tuberculosis

Control of Malaria

• Reduction of malaria cases by 65% globally since 2000
• Malaria can infect people multiple times, and immune response is complex, hindering vaccine development
• Insecticide-treated nets can be very effective in reducing infection
• Two key proteins essential for malaria parasites to escape red blood cells identified as promising drug targets

Tuberculosis

• Chronic bacterial infection causing high morbidity and mortality
• Airborne disease usually transmitted only after prolonged exposure
• 1.8 million deaths in 2015
• Typically infects lungs, but can also infect other organs at later stages
• Myobacterium tuberculosis has a complex, relatively impermeable cell wall and is slow-growing, making it difficult to detect and cure

Global Tuberculosis Status 2016

• 10.4 million people fell ill with TB, and 1.7 million died from the disease
• Over 95% of TB deaths occur in low- and middle-income countries
• TB is a leading killer of people with HIV, with 40% of HIV deaths attributed to TB
• Multidrug-resistant TB (MDR-TB) remains a public health crisis and health security threat
• WHO estimates 600,000 new cases with resistance to rifampicin
• 53 million lives saved through TB diagnosis and treatment between 2000 and 2016

Prokaryote Genome Organization and Gene Expression

• Prokaryotes are extremely flexible in terms of gene content and expression pattern
• Phenotypic variation must be used carefully in classification and management strategies

Prokaryote Structure

• Primary components of prokaryote structure are the cell wall and cell membrane(s)
• Function: protective barrier against environment, separates cytoplasm from exterior
• Different morphologies have different surface area/volume ratios, affecting survival, compromise, and nutrient uptake

Gram-Negative and Gram-Positive Cell Envelopes

• Gram negatives have a thin peptidoglycan wall and an outer membrane, while Gram positives have a thicker peptidoglycan wall connected to the plasma membrane
• The Gram stain differentiates between Gram-negative and Gram-positive bacteria

Mucosal Membranes

• Mucosal membranes have a tightly packed epithelium covered by secreted mucus
• Resists penetration, traps microbes, and often has antimicrobial secretions
• Protects against attachment, colonization, and invasion of undesirable pathogens

Respiratory System

• Nose contains tiny hairs that mechanically filter inhaled air of organisms and foreign matter
• Mucociliary blanket or 'escalator' removes foreign bodies from the respiratory tract

Gastrointestinal Tract

• Stomach: gastric juice is pH 2-3, killing microbes
• Small intestine: pancreatic enzymes, bile, and Gut Associated Lymphoid Tissue prevent pathogenic microbes
• Colon: normal flora, lysozyme, and peptides help prevent establishment of pathogenic microbes

Genitourinary Tract

• Normally sterile, with low pH and urea
• Distal urethra has some microorganisms
• Vagina has lactic acid bacteria, keeping pH low and unfavourable for many microbes

Eye

• Conjunctiva lines the interior surface of the eyelids and secretes mucus
• Motile by peritrichous flagella