Water Sources and Quality of Water PDF

# Water Sources and Quality of Water ## Water Requirement - Rural: 50-55 LPCD (Litres per capita in day). - Urban: 150-160 LPCD (Require more water d/t sewer system). ## Type of Water Supply - **Continuous**: 24×7 ↓ chances of contamination. - **Intermittent**: Only at fixed intervals of time....

# Water Sources and Quality of Water ## Water Requirement - Rural: 50-55 LPCD (Litres per capita in day). - Urban: 150-160 LPCD (Require more water d/t sewer system). ## Type of Water Supply - **Continuous**: 24×7 ↓ chances of contamination. - **Intermittent**: Only at fixed intervals of time. ## Water Sources 1. Rain water. 2. Surface water (Sea, Ocean, Lakes, Canal, River, Impounding reservoirs). 3. Ground water (Pure source of water). **Note:** - Drinking water supply: River > Canal. - Impounding reservoirs: Catchment areas for collection of water. ## Wells - **Source of groundwater.** ### Types #### Based on Material 1. **Pucca**: Brick lined well. 2. **Kutcha**: No brick lining. #### Based on Depth 1. **Shallow**: Above 1st impervious layer. 2. **Deep**: In between the impervious layer. ### Based on Design - **Sanitary Well**: - Conical shape prevents contamination. ### Based on Engineering - **Tubewell**: - Very low permeable layer - Shallow aquifer (fine materials) - 1st impervious layer - Deep aquifer (coarse materials) - Shallow tubewell (above) - Deep tubewell (below) - Motorised deep tubewell ### Others - **Natural/Artesian well.** - **Step well** ## Water Quality Parameters ### Physical - **Temperature**: Ambient/room temperature. - **Colour**: < 15 True colour units/hazen units (Ideal: 5 TCU). - **Odour**: Odourless. - **Turbidity**: <I NU (Nephelometric units). ### Chemical - **Chlorination**: - Method of disinfection. - Pathogens resistant to chlorination (at regular levels): 1. Hepatitis A 2. Entamoeba histolytica 3. Actinomyces 4. Mycobacteria 5. Giardia 6. Cryptosporidia. - Mechanism of chlorination: - $Cl + NH_3 + Cl$ Chloramine compounds - $Cl$ Residual chlorine compounds ## Chlorine Demand - Amount of chlorine required to achieve breakpoint chlorination. - Measured by Horrock's apparatus. ## Hardness - Ca and mg salts. - Temporary: Bicarbonates. - Permanent: Sulfates/Phosphates. - Measured in: $1$ meq/l = 50 mg of calcium carbonate (CaCO3). | Levels of hardness (meq/l) | Category | |------------------------------|---------------| | <1 | Soft | | 1-3 | Moderately hard| | 3-6 | Hard | | >6 | Very hard | ### Treatment 1. Boiling 2. Lime 3. Soda Ash: Nearest: Treat Temporary Hardness. 4. Zeolite (Sodium Zeolite): - Ion exchange method. - $Na_2 Al_2 Si_2 O_8 .H_2 O$. - To treat any type of hardness. ## Other Chemical Parameters 1. Nitrate + Nitrite ratio - < 50 mg/lt < 3 mg/lt - From Faecal (organic) compounds - Concentration of nitrate + Concentration of Nitrite < 1 ppm - Guideline value of nitrate + Guideline value of nitrate 2. Fluoride level: - 0.5 - 0.8 mg/lit - Deficiency: Dental caries - Excess: Fluorosis - Drinking water (GOI) = 1 ppm 3. Total Dissolved Solids (TDS): - Inorganic compounds, minerals. - Permissible limit: < 500/600. - Ideally: 200 - 300. 4. Chlorides: - <250 mg/lit. - Taste & Laxative: > 250 mg/lit. - Maximum permissible: < 600 mg/lit. ## Biological ### Coliform Count - Measured E. coli in water sample. - Permissible Limits : o per 100 ml of sample water. ### Water Collection - Winchester bottle (Sterile containers). - Collect clean catch specimen. ### Mccartney Chart - Based on most probable number method. - Procedure: - Liquid broth: 25 tubes with different titrations of water - Visualisation of colour and gas - False positive: D/t presence of Klebsiella - Eijkman test: To rule out Klebsiella ### If Contamination (Fecal) is Present - Distant/Remote: Clostridia perfringens - Nearby/Recent: Fecal streptococci ## Radiological - α particle activity: < 0.5 becquerel/L. - ẞ particle activity: < 1 becquerel/L. # Water Purification Methods ## Water Purification on Large and Small Scale ### Purification on Large Scale 1. **Storage**: - In 5 to 7 days: Bacterial load (Impurities) ↓ by 90% (d/t action of oxidising bacteria). - Ideal time for storage: 10-15 days. 2. **Filtration:** - **Rapid sand filters:** - Forms scum - Alum mixes with impurities - Turbines churning water - D/t gravity: Paterson's filter - With pressure: Candy's filter - Sand (1-1.5 metres) - Gravel - Percolation of water - Drainage system - Domestic supply - **Slow sand filters:** - Not the influence of pressure/gravity. - Long-standing water. - Forms algae/planktons (Within the sand bed) - Biological/vital/zoogleal/ Schmutzdecke layer - ↑ oxidation of matter ↑ purity | | Rapid sand filter | Slow sand filter | |---------|---------------------------|--------------------| | Capacity | 200 mgad | 2-3 mgad | | Rate of filtration | 5-15 m³/hr/m² | 0.1-0.5 m³/hr/m² | | Loss of head | 6-8 ft | 4 ft | | Sand gravel | .4-0.7 mm | 0.2-0.3 mm | | Preliminary treatment | Sedimentation tank | - | | Washing/cleaning | Backwashing | Manual scraping (2-5 cm) | | Purity | 99% | 99.999% | | Space | Lesser | Larger | 3. **Disinfection:** - **Chlorination**: - Level of chlorination: > 0.5 ppm with contact time of 1 hour. - Most frequently used: (d/t residual effect). - **Ozonation**: - Method: Tubes (1.5 - 3 cm of water) - Oxidation: Ozone gas (2-2.5 mg/L with contact time of 20 minutes) - Kill pathogenic bacteria and all live forms. - Disadvantages: Very expensive. No residual effect (Combination can occur in the process of supply). - **Membrane process:** - Expensive procedure. - Size of pores: ≤ 10. - Type of filtration: Nanofiltration, reverse osmosis, ultrafiltration. - Disadvantage: Raw water wastage. ### Purification on Small Scale - Small scale: small communities, villages, family level. 1. **Disinfection of wells:** - Volume of water = $ πr^2h$ - $π = 3.14$ - r: Diameter of well - h: Height of well - Amount of bleaching powder: using Horrock's Apparatus. - Assessed by: male MPW (multipurpose worker). 2. **Double pot method:** - Method of mixing bleaching powder. - If: - Volume of water: 4500-6000 L. - Daily water requirement: ≤ 300 - 450 L/day - Effective for: 2 - 3 weeks. 3. **Household water purification:** - **Boiling**: Most advanced, least followed. Kills pathogenic bacteria. - **Chemical disinfection:** 1. Bleaching powder: 2.5 g for 1000 L of water. 2. 0.5% chlorine solution: 4 kg of bleaching powder in 20 L of water with contact time of 1 hour. 3. High test hypochlorite/ perchloron solution. 4. Chlorine tablets/halazone tablets: - Supplied by NEERI (National Environmental Engineering Research Institute, Nagpur). - **Iodine**: 2% ethanol iodine (2 drops for a litre of water). - **Potassium permanganate**: Few drops to be used. Disadvantage: Bad odor, purple color. - **Household filters**: Currently used only in rural areas. 1. Katadyn filters. 2. Pasteur chamberland filters. - **UV radiation**: 235 arc lamp (No residual effect). - **Membrane filters:** | Membrane filtration process | Pore size (μm) | Usage | | :--------------------------- | :--------------- | :------ | | Low pressure: | < 0.2 | Community level | | 1. microfiltration | <0.1 | - | | 2. Ultrafiltration | < 0.01 | - | | High pressure: | <0.003-0.001 | Household | | 3. Nanofiltration | - | - | | 4. Reverse osmosis | - | - | - **Reverse osmosis**: Four cylinders. 1. Sediment filter: For big impurities. 2. Carbon block filter: For chemical disinfection. 3. Gag filter: ↑ taste and ↓ odor. 4. RO membrane. - **Solar disinfection: SODIS water.** - **Swimming pool sanitation:** - Area: > 24-25 ft² per swimmer. - Water change: > 15% changed within 24 hours. - PH: 7.4-7.8 - Chlorination: >1 ppm ## Water Disease - **Waterborne disease:** By means of drinking infected water. Eg: cholera, typhoid, acute gastroenteritis. - **Water-based disease:** Exposure to infectious agent in water. Eg: Dracunculosis (Guinea-worm disease), swimming pool conjunctivitis, leptospirosis. - **Water-washed disease:** Disease cured by washing with water. Eg: Diarrhoea, trachoma, scabies. - **Water-related disease:** Water is required to complete the life cycle of infectious agent. Eg: Any vector borne disease except Kala azar. ### SAFE strategy in Trachoma - S: Surgery - A: Antibiotics - F: Facial cleanliness - E: Environmental hygiene # WASH Programme (UNICEF) - WASH: Water Sanitation and Hygiene - National Water and Sanitation Program 1950 - Implementation of WASH programme in India. - Objective: One water source available to at least 250 houses within 30 minutes of approach. ### Problem village - No water within 1.6 km. - Water source > 15 meters below ground. - Excess salinity/ Hazardous chemicals/ minerals/radioactivity. - Eg: villages in central India, Maharashtra, Madhya Pradesh, Gujarat, Rajasthan. ## Water Wise Initiatives - **Environment friendly practices**: - Rain water harvesting. - **Community** - **Individual** ### Swajaldhara scheme - Goal: To provide safe clean drinking water to everyone. - Level 1: village/community → Grants. - Level 2: District. ## Housing, Ventilation, light, Sound, Radiation ### Housing & Ventilation #### Housing - **Types:** - Kutcha: No cemented roof - Pucca: Cemented roof #### House - Road: >15 metres away. - Cattle: >25 metres away. - Rooms: > 2 rooms + Living + Kitchen (To be located within the house) - Water source: within house, not > 100 metres away (Ideally). - National WASH progam: - I source for 250 houses - Within 30 min of walking distance. - Door: At least 30-32" x 80" - For smaller rooms: > 1/5th of floor area (min 24") - Good housing practices Govt of India => 2/5th of floor area - Window: > 1/5th of floor area >3 ft above ground level. - **Overcrowding:** - Gender: 2 persons, age >9 yrs, of opposite gender sharing same room (Except: Husband & wife) - Based on space: - 1 person living in < 70 ft² (square feet area) - 2 people < 110 fta - 3 people < 150 ft². (Add 40 ft³/ person) - Space per person: > 500 ft³/ person (Ideal: 1000 ft³/person). #### Ventilation - Types: - In Out: Exhaust (-ve) - Out In: Plenum (+ve) - Mixed: Good ventilation - Cross ventilation: Door and windows on opposite walls. ### Light, Sound & Radiation #### Light - Criteria: Not < 100 lux. | Parameter | Name | Units | Other Units | |-------------------------------|--------------------------|------------|--------------| | Brightness of point source | Luminous intensity | Candela | Candle Power | | Flow of light | Luminous flux | Lumen | - | | Amount of light reaching surface | Illumination | Lux | Foot candle | | Amount of light reemitted by surface | illuminance | Lumen/cm² | Foot lambert | | | Brightness | - | - | | | luminance | Lambert | - | #### Daylight Factor (dF): - Illumination inside house x 100 - Illumination outside house - Minimum dF for: - dF <2: Dark room. - Living/bed room: >8. - Kitchen: 710. #### Sound - Intensity: Decibels. - Frequency: Hertz. - Phon: Psychoacoustic measure. - Whispering range: 20-30 dB. | Permissible sound limits | Recommended Limit | |-------------------------|--------------------| | Residential area | <40 dB | | Commercial area | <60 dB | | Factories or industries | <60 dB | | Hospital wards | <35 dB | - Hearing loss: Depends on duration of exposure. - Auditory fatigue: >90 dB for 4-6 hours, >120 dB for I min. - Temporary hearing loss: 7110 dB. - Permanent hearing loss: >120-130 dB (>4-6 hours continuously). - Rupture of tympanic membrane: >160 dB. ### Radiation - Units of radiation measurement: |Unit of | Units | Definition | |----------------|-------------------------|-----------------------------------| |Radiation exposure| Coulomb/kg or Roentgen | Amount of radiation present per ml. | | Absorbed dose | 1 Gray = 100 rad | Amount of radiation required to raise 1 joule of energy from a mass of 1 kg. | | Dose equivalent | 1 sievert = 100 rem | Damage done in tissues with 1 rad exposure. | - Sources of radiation. - Permissible limit <5 Rad/year. - I. Natural: |Source: | mRad/year | |----------------------|-----------| | Cosmic: From sun | 30-50 | | Terrestial: From mountain, rock, earth | 500-1000 | | Atmospheric: From surrounding air| - | | Internal: From humans | 0.5 | - II. man made: - X ray, PET scan, fluoroscopy: 2.5-3 Rad (exposure) - Types: - Ionizing: α, β, γ rays, x rays. - Non ionizing: Radiowaves (max wavelength), infrared waves, microwaves, UV rays (Lowest wavelength). - Wavelength (2): α < β < x rays < y rays < Non ionizing radiation. - Penetrating power: $λ α 1/Penetrating power$ (Inversely proportional) - α > ß > x rays > y rays > Non ionizing radiation. ### Radiation Effects 1. **Stochastic (Random):** - Severity ↑ with dose without any threshold limit. - Eg: Ca breast, ca thyroid, leukemia. 2. **Deteriministic:** - Severity ↑ with dose with a threshold limit. - Eg: GI effects, blood cell changes (RBCS are more vulnerable to radiation) - Intensive symptoms, hemorrhage, capillary leaks, organ damage Acute radiation sickness 3. **Hereditary (Depends on genotype).** #### Protection from radiation 1. Shortest duration of exposure. 2. Maintain farthest possible distance. 3. Using shields. | Exposure (Rads) | Effect | |-----------------|----------| | 50-100 | GI effects, blood cell changes | | 150-1000 | Intense symptoms, hemorrhage, capillary leaks, organ damage; Acute radiation sickness | | More than 1000 | Multiple organ dysfunctions, genetic level changes, death (within a week). | # Waste Management ## Types of Waste | | | |----------------|-------------------| | **Solid** | **Liquid** | | Garbage | Sewage | | **Organic**: Kitchen waste | - | | **Rubbish** | Fecal matter | | | AKA Black water | | **Inorganic**: Rubber, plastic, | - | | | metal, glass | | | Sullage | | | Kitchen, | | | bathroom water | | | No fecal matter | | | AKA grey water | | **Ash** | Powdered waste | ## Solid Waste Disposal - Swachh Bharat-Abhiyaan: 2 Oct 2014. - Mx of solid waste. - Strategy: Reduce; Recycle; Reuse. ## Methods - **Dumping**: Most non-sanitary method. - **Recycling**: Best. - **Controlled tipping:** - Trench method: 2-3 m deep x 4-10m length. Wastes disposed into the trench with some soil. - Expensive. - Requirement: 1 acre/10,000 population/year. - Area method: Layer of soil on top of wastes. - m/c used. - Not an efficient method d/t heaping up of waste. - Ramp method: Used in hilly areas. Using successive ramps along the slopes. - **Incineration:** - Burning wastes under high temperature. - Temperature: 800 - 1000°C. - Pyrolysis: Burning wastes at 1200°C. Leaves no ash. - Disadvantages: - High moisture wastes, explosives cannot be incinerated. - Causes air pollution. - **Manure pits:** - Covered cemented/plastic pits. - Used for composting of waste. - Duration: 4-6 months. - **Bangalore method:** - AKA: Layering method. - Alternating layers of sewage & rubbish. - Deep pits of 3 ft deep x 6 ft width x 30 ft length. - Anaerobic method. - Refuse: Sewage ratio = 1:3 (2 inch refuse, 6 inch sewage). - **Burial method:** - Pit of 1 x 1 x 1-2 ml in the ground. - Used in temporary camps. - 1 pit/200 people / x 7 days. - **Pulverization:** - AKA mutilation/shredding. - Done for metallic wastes. - **Mechanical composting:** - Pulverized waste + garbage = mechanical compacting. - Anaerobic method. ## Liquid Waste Disposal ### Strength of Sewage 1. **Biological Oxygen Demand (BOD):** - Amount of oxygen consumed by 100 gm of sewage in a specified time (sd) at 20°C for aerobic digestion. - m/c used. 2. **Suspended Solids:** - Suspended solids in sewage system. | BOD | Sewage | Suspended Solids | |-----------------------|---------------------|---------------------| | <100 mg/L | Weak | <100 mg/L | | 100-300 mg/L | Moderate | 100 - 500 mg/L | | >300 mg/L | Strong | 500 mg/L | ## Sewage Treatment Plant - **Primary Rx**: - Sewage ----> screen ------> Grit filter -- > Sedimentation Tank -----> (Anaerobic digestion for 6-8 hrs.) ----> Sludge digester ----> Drying beds, methane gas, manure - **Secondary Rx**: - 40% reduction in Coliforms. - Biological treatment - Aeration Aerobic - Trickling filters - Aeration tank - 2° Sedimentation tank - Effluent. - Chlorinate. - Irrigation. - Sunlight. ## Other Methods - **Oxidation pond/ ditches:** Sewage retained for 2-3 months. Good manure. - **Aerated lagoons:** Mechanised. - Mechanism: - Upper layer: Aerobic. - Bottom layer: Anaerobic. ## Latrine Types - **Service**: Manual disposal of sewage. - **Non-service**: Presence of sewer system. ### Non - Service Latrine: - **Bore hole**: - Not connected to sewage. - 12 inch x 20 ft. - 1 family of 5-6 people / 1 year. - Changed every year. - Causes soil pollution. - **Pit latrine:** - 24 inch x 10 ft. - 1 family of 5-6 people / 5 years. - Sealed type of latrines. - Chemicals can be added to the latrines. - Used in area with no sewer. - **Sanitary latrine with water seal**: - REA type: Research cum action latrine. - Height of water seal: 2.5 cm. - Connected to sewer. - Prevents entry of rodents. - Odorless. - **Septic tank**: - Fecal matter from latrines collected in septic tank via pipelines. - Sealed area in household level. - Anaerobic digestion inside the tank, products then subjected to sunlight & air. - Aerobic digestion (Anaerobic > Aerobic). - Size: > 500 gallons. - Duration: 4-5 years, Cleaned every 5 years. - **Aqua privy:** - Septic tank within the latrine. - Direct defecation into the septic tank. - Presence of water inside the tank. ## Waste Digestion & Disposal - **Oxidation ditch:** 1 acre. - **Oxidation pond:** 22 acres for 1 lakh population. - **Aerated lagoon:** 2.5 acre. - **Indore method:** Aerobic. # Entomology: Mosquitoes - Entomology: Science of study of insects. - Class Insecta vs Arachnida vs Crustacea | Class | Parts | Legs | Wings | Habitat | Examples | |----------|---------------------------------------|------|-----------------|---------|--------------------| | Insecta | Head, thorax, abdomen | 3 | Present (may/may not fly) | Land | Mosquitoes, flies, lice, flea | | Arachnida | Abdomen, cephalothorax | 4 | No wings | Water | Ticks, mites | | Crustacea | Abdomen, cephalothorax | 5 | No wings | Water | Cyclops (Guinea worm disease) | - Modes of transmission: 1. Direct: Via direct contact or vector. 2. Mechanical: via the footpad of flies. 3. Biological: | Type | Propagative transmission | Cyclo-developmental transmission | Cyclo-propagative transmission | |:------------------------|:-------------------------|:-----------------------------|:-----------------------------| | Change in no. of organisms | Yes | No | Yes | | Change in shape/size/ developmental stage of organism | No | Yes | Yes | | Example | Plague bacilli in rat flea | Filarial worms in Culex mosquito | Plasmodium falciparum in Anopheles mosquito | ## Differences In Mosquitoes Based On Genus - **Mosquito families:** - Family Anophilline: Genus Anopheles. - Family Culicine: Genus Culex, Aedes, mansonia. ## Anopheles vs Aedes vs Culex vs Mansonia | | Anopheles | Aedes/Tiger Mosquito | Culex | Mansonia | |-------------------|---------------------------------|-----------------------|-------|----------| | Disease | Malaria (Highest deaths among vector borne diseases) | Dengue, Yellow fever, Chikungunya | Japanese encephalitis, Lymphatic filariasis | Lymphatic filariasis | | Breeding Place | Clean stagnant water (Roadside water, pothole water) | Artificial stored water (in coolers, flower pots, collected rainwater) | Dirty polluted water | Large water body with aquatic vegetations | | Eggs | Single, boat-shaped with lateral floats | Single, cigar-shaped | Clusters, in rafts (sheets) | Star-shaped clusters | | Larva | Surface feeder | Bottom feeder (Has siphon tube to breathe) | - | Bottom feeder: Attach to roots of aquatic vegetations via siphon | | Peak biting time | Dawn & dusk | Day time: 2 h after sunrise & 2h before sunset | Midnight | Morning & evening | | Habitat | Exophilic (Outside the house) | Endophilic (Inside the house) | Exophilic (Night). Endophilic | Exophilic | ## Bite | | Anopheles | Aedes/Tiger Mosquito | Culex | Mansonia | |-----|-----------|-----------------------|-------|----------| | Bite | Mildly painful | Painful | Stingy/burning bite | Relatively painless | | | Head down position : Inclined/landing position | Parallel to ground | Hunch back position (Because of neck) | Squatting position | | Resting position | Anopheles mosquito in inclined position | Aedes mosquito parallel to ground | Culex mosquito in hunchback position | Mansonia mosquito | | Flight range | 2-3 km | 100-200m | 11-13 km | 2-3 km | | Body & Wings | Spots on wings | Stripes on legs & body. | Brown colour, small body, big wings & causes buzzing. | Long legs, large body | # Entomology: Lice, Ticks, Mites and Sandfly ## Sandfly - Types: | Sand fly | Disease | Geography | |---------------------|----------|------------| | Phlebotomus argentipes | Kala azar | Bihar, West Bengal, Orissa, Uttar Pradesh, Assam. | | Phlebotomus papatasi | Sand fly Fever | - | | Phlebotomus punjabensis | - | - | | Phlebotomus sergenti | Oriental sore | - | - Special features: - 1.5-2.5 mm in size (smaller than mosquito). - Nocturnal insect (Bites at night). - Doesn't fly but hops to a maximum of 40-50 yards. - Predilection for lower limbs & painful bite. - Habitat: Cool damp places like burrows/cracks of wall. - Prevention & control: - Sand fly killed by DDT & BHC - Insecticide of choice under NVBDCP (National vector Borne Disease Control Programme): - Synthetic pyrethroids. - Malathion ## Louse/Lice - Types: - Head louse. - Body louse. - Pubic louse: Strongest. - Special features: - Elongated, wingless ectoparasite. - 3 pairs of legs with claws. - Dorsoventrally flattened. - Antenna: straight. ### Public Health Importance | Disease | Causative organism | |----------------|---------------------| | Relapsing Fever | *Borrelia recurrentis* | | Epidemic typhus | *Rickettsia prowazekii* | | Trench Fever | *Rickettsia quintana* | | Dermatitis | Multiple organisms | - Mode of transmission: Direct contact/Fomites. ### Life Cycle - Life span of adult louse: 1-2 months. | Stage | Timespan | |-------|----------| | Eggs (nits) | 5-9 days | | Adult | 10-15 days | | Larva(nymph) | - | ### Prevention & Control - 0.5% malathion/carbaryl dust (Head louse). ## Flea - Special features: - Wingless ectoparasite. - 3 pairs of legs with claws and antenna facing backwards. - Body: Head, thorax, abdomen (9-10 segments). - Bilaterally flattened. - Bites are painful. - Uni-species (Specific for each species). - Types and public health importance: | Flea | Species | Disease | |--------------------|-----------------------|---------| | Rat fleas (Oriental) | *Xenopsylla cheopis* | Plague | | Human fleas | *Pulex irritans* | Trench fever (Louse > Flea) | | Sand flea | *Tunga penetrans* (Rajasthan) | Dermatitis, ulcer & gangrene in lower limb/toes | ### Transmission of Plague: - Mode: Bites/mechanical transmission. - Type: Propagative transmission. - Vector: Partially blocked flea (more dangerous). ### Mode of Transmission: Life Cycle | Stage | Timespan | |-------|----------| | Egg | 1 week | | Larva | a weeks | | Adult | 7-10 days | | Pupa | - | - Life span of flea: 1-3 years. ### Prevention and Control measures: - 5% malathion/2% carbaryl dust. - Susceptible to DDT/BHC. - Personal protection: Diethyl toulamide, Benzyl benzoate ## Ticks - Special Features: - No wings. - 4 pairs of legs. - Fused cephalo-thorax & abdomen. ### Life Cycle | Stage | Timespan | |-------|----------| | Egg | 1-3 wks | | Larva | 3-10 days | | Nymph | - | | Adult | 1-2 wks | #### Types: ##### Hard Tick - Rapid life cycle. - Becomes adult in 4 months. ##### Soft Tick - Becomes adult in 9-10 months. | | Hard Tick | Soft Tick | |---|---|---| | Life cycle | Rapid Life cycle. Becomes adult in 4 months | Becomes adult in 9-10 months. | | Chitin on exoskeleton | + | - | | Head | Visible | Not visible | | Feeding | Always on the host. Will die once out of body. | Not visible. Nocturnal Feeding. Can starve for weeks/months. | ### Diseases of Public Health Importance #### Hard tick (Ixodidae) - Tick typhus. - Tick Paralysis. - Tularemia. - Viral encephalitis. - Viral Fever. - Viral hemorrhagic Fever. - Babesiosis. #### Soft tick (Argasidae) - Q Fever. - Relapsing Fever. - Kyasanur Forest disease (KFD). - Caused by hard tick too. ### Prevention and control: - Personal protective measures. - Benzyl benzoate. ## Mites - Special Features: - 4 pairs of legs. - Thick & long anterior legs. ### Types #### 1. Thrombiculid mite/ Berry bug: - Infective biting stage: larva. - Transovarian transmission: #### Public Health Importance: - Rickettsia orientalis (Orientia tsutsugamushi): Obligate intracellular parasite of the mite. - Causes Scrub typhus. #### 2. Itch mite/Sarcoptes scabiei: - Special features: - 4 pairs of legs: Thick anterior & thin posterior legs. - Life cycle: Completed in 10-15 days (Short). ### Public Health Importance: Scabies - Lesion: Ovigerous burrows/tunnel. - C/f: Intense itching at night. - Mode of transmission: Direct contact/fomites. #### Prevention and Control: - 25% benzyl benzoate (DOC): 2-3 times a week. - HCH/lindane: Twice a week. - Permethrin/Crotamiton/Tetmosol ointment. # Mosquito Control Measures and Insecticides ## Insecticide Formulations: | Formulation | Form Used | Residual effect | Additional Features | |--------------|-----------|----------------|----------------------------------------------| | Spray | Solution | - | - | | Mist/Fog | Solution | Absent | Ultra Low Volume Fogging (ULV-fog): Very fine particles of mist - Better. Lesser respiratory Side effects. | | Suspension | Dispersed solid particles in solvents. | Longer | - | | Emulsificants | Mixed with paint & used. | Longer | - | | Dust/Granules | Solid formulation | - | Used against larvae of Culex/mansonia. | ## Integrated Vector Management (IVM) for Mosquitoes - Control measures: - Source reduction (Best): Remove water source. - Anti-larval Measures. - Anti-adult measures. - Personal Protection measures. - **Anti-larval Measures**: - 1. Physical methods: mosquito larvicidal oil (MLO) - MOA: Asphyxiation of larvae. - Duration of contact of oil with water: 7-8 days. - Effective against Anopheles larvae. - Disadvantages: Expensive. Makes water unfit for drinking/fishes. - 2. Chemical methods: | Type of poison | Stomach poison | Contact poison | |----------------|-----------------|----------------| | Color | Paris Green | Abate (Better) | | | Emerald green |