HIV Sero Surveillance

Definition

HIV Surveillance: The Broader Framework

1. (a) HIV Sentinel Surveillance
2. (b) HIV Sero-Surveillance
3. (c) AIDS Case Surveillance
4. (d) STD Surveillance
5. (e) Behavioural Surveillance
6. (f) Integration with surveillance of other diseases like tuberculosis

• Park's Textbook of Preventive and Social Medicine, p. 490

HIV Sero-Surveillance vs. HIV Sentinel Surveillance

Key Principles of HIV Sero-Surveillance

1. Unlinked Anonymous Testing (UAT)

• Eliminates participation bias (people at high risk won't refuse testing)
• Eliminates selection bias
• Protects patient confidentiality
• Gives a true picture of population prevalence

2. Cross-Sectional Survey Design

3. Representative Sample Size

4. Clinical-Based Approach

Objectives of HIV Sero-Surveillance (from Park's Textbook)

1. To determine the level of HIV infection among the general population and high-risk groups in different states
2. To understand the trends of the HIV epidemic over time
3. To understand the geographical spread of HIV infection and identify emerging pockets
4. To provide information for prioritization of programme resources and evaluation of programme impact
5. To estimate HIV prevalence and burden in the country

Three Main Approaches to HIV Sero-Surveillance (UCSF)

1. Sentinel surveillance - Testing at fixed sentinel sites (antenatal clinics, STD clinics, targeted intervention sites for high-risk groups)
2. Population-based surveys - Household or community surveys with HIV testing to get geographically representative data; more accurate but expensive
3. Surveys of special/high-risk populations - Targeted surveys in groups with higher HIV risk (sex workers, IDUs, MSM, truckers, migrants)

Population Groups Surveyed in India (HIV Sentinel Surveillance 2016-17)

• Park's Textbook of Preventive and Social Medicine, p. 490-491

Data Collection Protocol (India, 2016-17 Round)

Uses of HIV Sero-Surveillance Data

• Targeting prevention and care programmes
• Monitoring and evaluation of national HIV programmes
• Resource allocation and programme planning
• Informing and educating the public
• Guiding scientific research
• Monitoring epidemic indicators
• Triangulation with other data sources
• Mobilizing political commitment and advocacy
• Categorizing districts (India classifies districts into Categories A, B, C, D based on surveillance data for resource allocation)

Relationship to "Second-Generation Surveillance"

• Serological data (from sero-surveillance) - to measure infection levels
• Behavioural data - to understand risk practices
• Programme data - to track coverage of services

Disinfectants: Types and Properties of an Ideal Disinfectant

Key Definitions (Park's Textbook)

• Disinfectant: A chemical (sometimes physical) agent that destroys disease-causing pathogens or other harmful microorganisms on inanimate objects, but may not kill bacterial spores.
• Disinfection: Thermal or chemical destruction of pathogens; less lethal than sterilization - destroys most recognized pathogenic organisms but not necessarily all microbial forms (e.g., spores).
• Antiseptic: A substance that prevents or arrests growth of microorganisms on living tissue.
• Sterilization: Renders a product free of all viable microorganisms, including spores.
• Sanitizer: Reduces bacterial contaminants to safe public health levels on inanimate objects.

Levels of Disinfection (Medical Microbiology 9e)

Properties of an Ideal Disinfectant

1. Broad spectrum - Wide antimicrobial activity against bacteria, fungi, viruses, and spores
2. Fast acting - Should produce rapid kill of microorganisms
3. Not affected by environmental factors - Active in the presence of organic matter (blood, sputum, faeces) and compatible with soaps, detergents, and other chemicals
4. Non-toxic - Not harmful to the user or patient; safe for skin and mucous membranes
5. Surface compatibility - Should not corrode instruments, metallic surfaces, or cause deterioration of cloth, rubber, or plastics
6. Residual effect - Should leave an antimicrobial film on the treated surface
7. Easy to use - Clear label directions; simple preparation and application
8. Odourless - Pleasant or no odour to facilitate routine use
9. Economical - Should not be prohibitively expensive
10. Solubility - Should be soluble in water
11. Stability - Stable in concentrate and in use-dilution over time
12. Cleaner - Should have good cleaning properties (remove organic matter)
13. Environmentally friendly - Should not damage the environment on disposal

Types of Chemical Disinfectants

1. Phenol and Related Compounds

2. Quaternary Ammonium Compounds (QACs)

• Cetrimide (Cetavlon): Bactericidal against Gram-positive organisms; 1-2% strength; less active against Gram-negatives.
• Savlon: Combination of cetavlon + chlorhexidine (hibitane); used for plastic appliances (1:20 aqueous, 20 min); clinical thermometers (1:6 in spirit, 3 min).
• QACs are cationic detergents useful for hard-surface cleaning, deodorization, skin disinfection, and mucous membrane application.

3. Halogens and Their Compounds

• Potent: bactericidal, fungicidal, sporicidal, tuberculocidal, virucidal.
• Bleaching powder (CaOCl₂, ~33% available chlorine): Used for water/faeces/urine disinfection; 5% solution for faeces (1 hour contact); unstable on storage.
• Hypochlorites (sodium/calcium): Most widely used; broad-spectrum; inexpensive; fast-acting; unaffected by water hardness; removes biofilms. Household bleach is 5.25-6.15% sodium hypochlorite.
• Chlorine tablets (halazone): For small quantities of drinking water.
• Chlorine dioxide, NaDCC, Chloramine-T: Retain chlorine longer for prolonged bactericidal effect.

• Bactericidal, fungicidal, virucidal, and lethal to spore-bearing organisms.
• Cheap, readily available, quick in action.
• Iodophores (Betadine/povidone-iodine): Sustained-release iodine; non-irritant; do not stain skin; used as antiseptic and for disinfecting blood culture bottles and medical equipment.

4. Alcohols

• Ethyl alcohol (industrial methylated spirit) and Isopropyl alcohol are the most commonly used.
• Effective at 60-90% vol/vol concentration - bactericidal, fungicidal, virucidal, tuberculocidal.
• Do NOT destroy bacterial spores.
• Activity decreases rapidly below 50% concentration.
• 70% alcohol kills all non-sporing bacteria in seconds, but activity disappears as it dries.
• Limitations: flammable, rapid evaporation, expensive.
• Most effective skin antiseptics: alcoholic solutions of chlorhexidine or iodine.

5. Aldehydes (Formaldehyde / Formalin)

• Highly toxic, irritant gas; precipitates and destroys protein.
• Effective against vegetative bacteria, fungi, and many viruses; only slowly effective against spores and AFB.
• 2-3% solution (20-30 ml of 40% formalin per litre): for spraying rooms, walls, furniture.
• Formaldehyde gas used for room disinfection; most effective at high temperature and humidity.
• Does not injure fabrics or metals.
• Glutaraldehyde: A high-level disinfectant used for endoscopes and heat-sensitive instruments.

6. Oxidizing Agents

7. Metals as Microbicides (Heavy Metal Salts)

• Silver: Used for prophylaxis of neonatal conjunctivitis, burn wound therapy, and coating indwelling catheters.
• Silver, zinc, iron, copper: Used for environmental control, water disinfection, or incorporated into medical devices.

8. Lime

• Cheapest of all disinfectants.
• Used as quick lime or 10-20% aqueous suspension ("milk of lime").
• Faeces/urine disinfection: mix with 10-20% suspension, allow 2 hours.
• As lime wash: treating walls.
• As deodorant: sprinkled in cattle sheds, public urinals/latrines.

Types of Disinfection (Process Classification)

• Concurrent disinfection: Applied immediately after infectious material is discharged from the body throughout the course of illness (e.g., disinfection of urine, faeces, vomit, contaminated linen, hands).
• Terminal disinfection: Applied after the patient has left the premises (recovery, death, or transfer) - thorough disinfection of the room and all articles.

Quick Summary: Disinfectant Types at a Glance