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Home , Airborne transmission, Chlamydia, Mucous membrane, Transmission (medicine)

Transmission

Infectious Mode of Classification by portal of entry

• Respiratory • Gastrointestinal • • Genital • Intrauterine or transplacental • Urinary • Personal contact • Water and food • borne Transmission: Source of Infectious Material , internal fluids and genital fluids do contain blood borne (HIV, HBV, z Blood: splashed on medical employee... HCV, CMV) z Internal Body fluids (cerebrospinal, pericardial, pleural, peritoneal, synovial, amniotic): medical setting. z Genital fluids (vaginal, prostatic secretions, ): sexual contact HBV, HSV to the newborn occurs during delivery. z Transplacental transfer of blood: . z Secretions: saliva, nasal discharge, sweat, tear, breast milk z Excretions: urine (schistosomiasis, ), (numerous enteropathogens) z Mucosal membranes (nasal, oropharyngeal, rectal, genital): sexual contact, delivery z Skin, squames z Tissue: Transplant, grafts, blood transfusion, blood components z Bites Gastro Intestinal / Fecal Oral Route (Contact)

Transmission by the fecal-oral route is the second most important mode of transmission after the respiratory tract

z excreted by the feces with z transmitted to the oral portal of entry envelopes do not survive exposure to through hydrochloric acid in z contaminated food, the , bile z contaminated water, milk, drinks acids in the , salts and z hands enzymes of the gut. z flies Small z Site of entry: without envelope (, , z oropharynx for some & coxsackie z intestinal tract for most viruses. able to resist. z Surviving through the upper GI tract is A and E essential. also transmitted by fecal oral route. Transmission by gastrointestinal route Fecal oral route

z Typhoid z Shigella z z Polio z Coxsackie, Echo, Reo z Norwalk agent z Rotavirus z , Hepatitis E Gastro intestinal transmission / Animal and Contaminated food product

Infections transmitted z z Campylobacter z Yersinia z Listeria

Salmonellas infect a wide variety of domestic animals, birds and other widlife. Food derived from salmonella infected animal (eggs, dairy product, meat) are the major source of if improperly prepared. Salmonella is less often transmitted by water or direct contact. Sexual transmission (mucous membrane transmission)

• Neisseria gonorrheae, trachomatis • pallidum • Hemophilus ducreyi • hominis, • Calymnatobacterium granulomatis • ± Shigella spp, Campylobacter spp • ± Group B streptococci • ±Bacterial vaginosis associated • HSV 1 and 2 • CMV Cyto megalo virus or herpes virus 5 • virus • Human papilloma virus • virus • HIV Human immunodeficiency virus 1 and 2 • • ± Entamoeba histolytica, Giardia lamblia • Phtirius pubis • Sarcoptes scabei Perinatal transmission (mucous membrane transmission)

Infections occur when •Neisseria gonorrheae the newborn goes through the birth • canal, from the •HBV or to the •HSV newborn. Transplacental transmission or

Microorganisms present in the blood of the •Syphilis mother •Toxoplasma go through the placenta to •CMV, HBV infect the fetus. •HIV In some cases it is difficult •HSV to differentiate between •, Varicella perinatal or transplacental transmission, since both modes of transmission are known to occur. Sexual transmission (mucous membrane transmission)

z Bacteria and viruses present in the genital fluids and on the mucosal membranes. z Transmitted to the mucosal membranes of the partner during sexual acts: membranes involved z vagina, z , z and z oropharynx. Arthropod borne transmission

may transmit infections by two mechanisms: Mosquitoes, z Passive transmission: flies, , z the insect acts as a live syringe true bugs, z no incubation time, , lice z no multiplication while carried by the arthropod z not specific, wide variety of microorganisms z not very inefficient. z Active transmission: z multiplication of microorganisms in arthropod z may be very effective: multiplied 1000 to million z requires a period of multiplication in the arthropod z very specific: some microrganisms & Food Poisoning

Food poisoning overlaps both classes of gastrointestinal transmission. z food from infected animal & improperly prepared: eggs, chicken with Salmonella, listeria in unpasteurized milk z food contaminated in environment: or Vibrio cholerae in raw oysters, z food contaminated during preparation from an infected food item: potato salad contaminated by Salmonella from raw chicken z food contaminated by human source: typhoid fever carrier. Skin or mucous membrane transmission

Transmission through the skin is the third most common mode of transmission of infection. Penetration through the intact skin is unlikely.

Break in the skin barrier may result from: z Needle , cut during a surgical procedure, accidental cut, crushing injury… z Bite: rabies z Arthropod bite for borne infections: , filariasis…

Some parasites are able to penetrate directly through the intact skin: larvae of hookworm, cercariae of schistosoma. MainMain ModesModes ofof TransmissionTransmission

Isolation guidelines in Institutions are based on these

AIRBORNEAIRBORNE

DROPLETDROPLET

AND Vectorborne, Common source: CONTACTCONTACT Water, Food, Direct Indirect Equipment, Rx Direct Indirect Droplet Transmission

A droplet of will fall in Droplets above 10 μ it h m are trapped in the ct 100 μmre t 10 seconds nose and usually do Di f 40 μm3 1 minute not make it to the bronchi 20 μm 4 minutes 10 μm 20 minutes 5-10 μm 30-45 minutes May reach lower respiratory tract ≤ 5 μm Droplet nuclei May be inhaled to alveoli Transmitted by Droplets

z Hemophilus influenzae z Meningococci z Pneumococcal infections (invasive, resistant) z BACTERIAL RESPIRATORY Infections z , Pertussis, pneumonic , z Strepto pharyngitis, , z VIRAL RESPIRATORY Infections z Adenovirus, Influenza, Mumps, Parvovirus, Rubella z ANY PAROXYSMAL (Pertussis?)

z Droplet nuclei = droplets less than 5 µ in diameter z from evaporation of larger droplets z or from direct formation during coughing, speaking, singing z Transmission may occur over long distance

Transmitted by D.N. z (Infectious) z Suspects of TB: request sputum smear z z Varicella z (hemorrhagic) CoughCough producesproduces goodgood dropletdroplet nucleinuclei

z Cough z 1 good cough produces 465 DN z after 30 minutes left: 228 DN (49%) z Speech: z count from 1 to 100 1764 DN z after 30 minutes left 106 DN ( 6%) Transmitted by Contact

• Gastrointestinal, respiratory, skin, wound infections • Colonization with multidrug resistant bacteria • Enteric infections, enteroviral infections in • RSV, parainfluenza, • Infectious skin infections: HSV, , , , staphylococcal furunculosis, • Viral hemorrhagic , viral • Some respiratory infections, in infants, children • , draining wound BBP & Skin Penetration

z Blood borne pathogens ( HBV, HCB, HIV) does not Risk of penetrate if blood was splashed exclusively on intact infection skin. after percutaneous z Need injury to the skin: with a hollow bore needle ot exposure to other sharp object (lancet, glass, scalpel) blood from infected contaminated with blood to cause an infection. patients, z Solid needle do not carry sufficient quantities of blood •HBV 30% to cause an infection ( ± ). •HCV 3% •HIV 0.3% z Viral titer is best predictor of risk of infection. z Mucosal membranes allow BBP penetration. Data from 21 studies worldwide on mucosal membrane exposure of 1107 HCW to HIV showed only one conversion: risk of 0.09%, 95%CI = 0.006% to 0.5%.

Precaution

Infectious Disease Epidemiology Isolation Precaution System for Institutions

IS AN EXPANSION OF UNIVERSAL PRECAUTIONS Standard Precautions

z Same concept as UNIVERSAL PRECAUTIONS z Precautions should be taken for any contact with Blood and Body Fluid (UP) z AND for any contact with secretions and excretions, mucous membranes, damaged skin, contaminated environment and equipment 5s Handwashing -1 10 z BEGINNING AND END OF DAY z BEFORE & AFTER EACH PATIENT CONTACT z BEFORE AND AFTER GLOVING z ANYTIME AFTER CONTACT WITH 5s z BLOOD & BODY FLUID -1 z SECRETIONS /EXCRETIONS 10 z MUCOUS MEMBRANES z DAMAGED SKIN z CONTAMINATED ENVIRONMENT z CONTAMINATED EQUIPMENT 5s Handwashing -1 10

Activity Number of Klebsiella on nurse’s hand Pulse /Blood pressure 100 - 1,000 Touching hand 10 - 100 Touch shoulder 7,000 Oral Temperature 100 - 1,000 Caswell & Phillips, British Med J Nov 1977: 1316

Hands of Patient nurses washed care and cultured: Activity Klebsiella cultured Îno Klebsiella Gloves

z FOR ANY CONTACT WITH z Blood and Body Fluids z Secretions & excretions z Mucous membranes z Damaged skin

ES z Contaminated environment V CE GLO LA or equipment EP R T ING NO SH If it is wet, red or dirty DO WA ND HA Wash, glove then wash Protection Face Shield

z RISK OF SPRAY z RISK OF SPLASH z of blood, body fluid, secretion or excretion z in FACE OR EYE Surgical Masks

z STANDARD PRECAUTIONS z For personnel to protect from splashes /sprays of BBF/ S E z DROPLET PRECAUTIONS z to prevent large droplets (>5μ) on/from patient z For patients z to prevent emission of droplet (large and droplet nuclei) Gown

z STANDARD PRECAUTION z To protect from splashes /sprays of large quantities of BBF/S E z CONTACT PRECAUTION z To protect contamination of personnel clothing Patient Placement

z AIRBORNE z Private room with ventilation control z DROPLET & CONTACT z Private room preferred z or cohort with same infection z or at least 3 feet between beds z Use common : do not mix in immunocom-promised patient with infected one Airborne Precautions

Small droplets (<5μ) emitted when coughing, & performance of procedures z ROOM WITH VENTILATION CONTROL z Negative air pressure z >6 air exchange /hour z HEPA filtered or exshaust out z PERSONAL RESPIRATOR z PATIENT wears if coughing & when transported Airborne Precautions Personal Respirator

z For Personnel z In AIRBORNE ISOLATION ONLY z To prevent inhalation of droplet nuclei z Main leak comes from poor fit around face Droplet Precautions

Large particle droplets (>5μ) emitted when coughing, sneezing, talking & performance of procedures

z Private room (*) z Mask when entering room

use STANDARD PRECAUTIONS at ALL times for ALL patients Contact Precautions

• Private room (*) • Gloves when entering room, • change glove after infectious contact • Gown when entering room if substantial contact will occur use STANDARD PRECAUTIONS at ALL times for ALL patients