Biological AgentsBiological Agents

ZoonosesZoonoses

Zoonoses are animal infections which may Zoonoses are animal infections which may be transmitted to people in the course of be transmitted to people in the course of their work. Common examples include:their work. Common examples include:– BrucellosisBrucellosis– Q FeverQ Fever– OrfOrf– PsittacosisPsittacosis– AnthraxAnthrax– GlandersGlanders

BrucellosisBrucellosis

Caused by the bacterium Caused by the bacterium Brucella abortusBrucella abortus, , which may infect people handling cattle or which may infect people handling cattle or pigs or their carcasses in abattoirspigs or their carcasses in abattoirs

Not very severe but involves loss of appetite, Not very severe but involves loss of appetite, headache, insomnia and slight feverheadache, insomnia and slight fever

In the UK a policy of eradication has been In the UK a policy of eradication has been pursued since the 60’s by destroying any pursued since the 60’s by destroying any infected cattleinfected cattle

Q FeverQ Fever

Known to occur in farm workers, Known to occur in farm workers, abattoir workers and veterinary abattoir workers and veterinary surgeonssurgeons

The causative agent, The causative agent, Coxiela burnetiiCoxiela burnetii, , has been found in cows and sheephas been found in cows and sheep

Not as serious as Brucellosis and takes Not as serious as Brucellosis and takes the form of cold or `flu-like symptomsthe form of cold or `flu-like symptoms

OrfOrf

A contagious pustular dermatitis of A contagious pustular dermatitis of viral origin, mainly affecting farm viral origin, mainly affecting farm workers, shepherds, sheep shearers, workers, shepherds, sheep shearers, butchers and abattoir workersbutchers and abattoir workers

Lesion enlarges and often becomes Lesion enlarges and often becomes ulcerated, exuding fluid and pusulcerated, exuding fluid and pus

Complete recovery occurs in about Complete recovery occurs in about 3 weeks3 weeks

PsittacosisPsittacosis

A virus-like bacterium of poultry, game A virus-like bacterium of poultry, game and other birdsand other birds

Can be fatal to man if untreatedCan be fatal to man if untreated Illness sets in suddenly after an Illness sets in suddenly after an

incubation period of 2 to 3 weeks with incubation period of 2 to 3 weeks with fever, headache and lethargyfever, headache and lethargy

Pulmonary symptoms follow in a few Pulmonary symptoms follow in a few days and mortality may be as high as days and mortality may be as high as 20%, particularly in the elderly20%, particularly in the elderly

AnthraxAnthrax

An acute infectious disease of farm animals An acute infectious disease of farm animals caused by a bacteriumcaused by a bacterium

Transmitted to man by contact with infected hair, Transmitted to man by contact with infected hair, hides, excrement or products such as bonemealhides, excrement or products such as bonemeal

Fatal without treatmentFatal without treatment Initial lesion rapidly becomes ulceratedInitial lesion rapidly becomes ulcerated Treatment is by penicillinTreatment is by penicillin Inhaling the pathogen causes pulmonary anthrax Inhaling the pathogen causes pulmonary anthrax

which is usually fatal in 3 or 4 dayswhich is usually fatal in 3 or 4 days

GlandersGlanders

An infectious disease of horses, donkeys An infectious disease of horses, donkeys and mules caused by the pathogen and mules caused by the pathogen Pseudomonas malleiPseudomonas mallei

Transmitted to humans by nasal or mouth Transmitted to humans by nasal or mouth secretions from the infected animalsecretions from the infected animal

Abscesses appear on hands, arms or faceAbscesses appear on hands, arms or face Lasts up to 4 months but is treatable with Lasts up to 4 months but is treatable with

modern antibioticsmodern antibiotics

Zoonose Control Zoonose Control StrategiesStrategies

Most common route of entry is via the Most common route of entry is via the skin, by way of open cuts, sores or skin, by way of open cuts, sores or abrasions which provide direct entry to abrasions which provide direct entry to bloodstreambloodstream

Other routes include inhalation of Other routes include inhalation of contaminated dusts, contact with contaminated dusts, contact with conjunctiva of eyes, direct injection by conjunctiva of eyes, direct injection by cuts from infected animals or animal cuts from infected animals or animal bites, and direct ingestion via handsbites, and direct ingestion via hands

Zoonose Control Zoonose Control StrategiesStrategies

First stage of control strategy is to First stage of control strategy is to assess those people at riskassess those people at risk

Factors to consider include:Factors to consider include:– work being carried outwork being carried out– susceptibility to infection of the susceptibility to infection of the

workersworkers– how infections might occurhow infections might occur– how likely exposure to infection ishow likely exposure to infection is

Zoonose Control Zoonose Control StrategiesStrategies

First priority for preventing occupational First priority for preventing occupational exposure to zoonoses is to eliminate the exposure to zoonoses is to eliminate the infections from the animal stock, usually by infections from the animal stock, usually by protecting exposed animals through protecting exposed animals through immunisation and improvement of their immunisation and improvement of their environmentenvironment

Workers should be protected by suitable Workers should be protected by suitable environmental hygiene controls and wearing environmental hygiene controls and wearing protective clothing including hand, arm, foot protective clothing including hand, arm, foot and leg protectionand leg protection

Zoonose Control Zoonose Control StrategiesStrategies

Where animal products likely to emit infected Where animal products likely to emit infected dust are handled (e.g. wool, skin, hides, pelts), dust are handled (e.g. wool, skin, hides, pelts), LEV and possibly RPE should be provided to LEV and possibly RPE should be provided to prevent airborne infectionprevent airborne infection

Specific immunisation of workers may be Specific immunisation of workers may be necessarynecessary

Clean & hygienic animal living conditions and Clean & hygienic animal living conditions and disinfection of stalls will also ensure better disinfection of stalls will also ensure better hygiene in factory premises and will reduce hygiene in factory premises and will reduce probability of infectionprobability of infection

Zoonose Control Zoonose Control StrategiesStrategies

Automation to reduce human Automation to reduce human contact and enclosure of aerosol-contact and enclosure of aerosol-producing activities will reduce producing activities will reduce exposure to infectionexposure to infection

Finally, medical checks, training and Finally, medical checks, training and information, procedures, instruction information, procedures, instruction and records will give added and records will give added protection to workersprotection to workers

Legionnaires DiseaseLegionnaires Disease Caused by the bacterium Caused by the bacterium Legionella pneumophiliaLegionella pneumophilia A type of pneumonia affecting the lungs and other A type of pneumonia affecting the lungs and other

organsorgans A number of conditions have been found to affect A number of conditions have been found to affect

rate of growth:rate of growth:– Water temp. in the range of 24-45Water temp. in the range of 24-45ooC. It does not survive C. It does not survive

about 60about 60ooC. Organisms may remain dormant in cool C. Organisms may remain dormant in cool waterwater

– Sediment, sludge, scale and organic material in water Sediment, sludge, scale and organic material in water systems can act as a source of nutrients, as can systems can act as a source of nutrients, as can organisms such as algae, amoebae and other bacteriaorganisms such as algae, amoebae and other bacteria

– Incorporation of Legionella in slime on surfaces can Incorporation of Legionella in slime on surfaces can protect the organisms from biocidesprotect the organisms from biocides

Legionnaires DiseaseLegionnaires Disease Infection caused by inhaling airborne droplets Infection caused by inhaling airborne droplets

or particles containing Legionella, which are or particles containing Legionella, which are small enough to pass deep into the lungs and small enough to pass deep into the lungs and be deposited in the alveolibe deposited in the alveoli

People at greatest risk include smokers, People at greatest risk include smokers, alcoholics and patients with cancer, chronic alcoholics and patients with cancer, chronic respiratory or kidney diseaserespiratory or kidney disease

Initial symptoms include high fever, chills, Initial symptoms include high fever, chills, headache and muscle pain. A dry cough soon headache and muscle pain. A dry cough soon develops and most patients suffer difficulty develops and most patients suffer difficulty with breathingwith breathing

Legionnaires DiseaseLegionnaires Disease

Water systems potentially at risk Water systems potentially at risk include:include:– Cooling towersCooling towers– Evaporative condensersEvaporative condensers– Hot/cold water services where occupants Hot/cold water services where occupants

are susceptible, I.e. health care premisesare susceptible, I.e. health care premises– Humidifiers and air washers creating a Humidifiers and air washers creating a

spray of water droplets above 20spray of water droplets above 20ooCC– Spa baths & poolsSpa baths & pools

Legionnaires DiseaseLegionnaires Disease Employers should manage the risk of Employers should manage the risk of

Legionella by:Legionella by:– Identifying and assessing sources of risk, taking into Identifying and assessing sources of risk, taking into

account potential for drop formation, water temperature, account potential for drop formation, water temperature, exposure probability and adequacy of controlexposure probability and adequacy of control

– Implementing and managing precautions and keeping Implementing and managing precautions and keeping records of the precautionsrecords of the precautions

Particular attention should be paid to populations Particular attention should be paid to populations which contain a high proportion of susceptible which contain a high proportion of susceptible people (hospitals or nursing homes) and situations people (hospitals or nursing homes) and situations where there is a large number of such people at where there is a large number of such people at risk risk

Legionnaires DiseaseLegionnaires Disease Main aim of control measures is to avoid Main aim of control measures is to avoid

conditions where Legionella can proliferate conditions where Legionella can proliferate and to avoid creating sprays or aerosolsand to avoid creating sprays or aerosols

Growth of Legionella can be inhibited by:Growth of Legionella can be inhibited by:– Avoiding water temperatures between 20-45Avoiding water temperatures between 20-45ooC C – Avoiding water stagnation & slimesAvoiding water stagnation & slimes– Avoiding use of materials which provide nutrient for the Avoiding use of materials which provide nutrient for the

organismsorganisms– Keeping the system clean and preventing a build-up of Keeping the system clean and preventing a build-up of

sedimentssediments– Using appropriate water treatment chemicalsUsing appropriate water treatment chemicals

Sick Building SyndromeSick Building Syndrome

Occupants suffer from measurably higher Occupants suffer from measurably higher incidence of illness than would be expected, for incidence of illness than would be expected, for no readily identifiable reasonno readily identifiable reason

Symptoms may include ear, nose and throat Symptoms may include ear, nose and throat irritation; skin rashes; lethargy; headaches; irritation; skin rashes; lethargy; headaches; respiratory infections and nausearespiratory infections and nausea

Occurs predominantly in air conditioned Occurs predominantly in air conditioned buildingsbuildings

Victims tend to be in low status repetitive jobs Victims tend to be in low status repetitive jobs and have little or no control over their working and have little or no control over their working environmentenvironment

Sick Building SyndromeSick Building Syndrome

Symptoms are more frequent in offices with Symptoms are more frequent in offices with large numbers of employees, and are also large numbers of employees, and are also reported with greater frequency in the reported with greater frequency in the afternoons than in the morningsafternoons than in the mornings

Cause is likely to be due to a number of factors, Cause is likely to be due to a number of factors, some of which may be biological, others notsome of which may be biological, others not

Airborne contaminants may cause SBS Airborne contaminants may cause SBS symptoms through several mechanisms, symptoms through several mechanisms, including toxicity, irritations, infection and including toxicity, irritations, infection and allergyallergy

Sick Building SyndromeSick Building Syndrome

Other factors include inadequate ventilation Other factors include inadequate ventilation and low humidityand low humidity

Several “temporarily sick buildings” have Several “temporarily sick buildings” have been “cured” by increasing ventilation, been “cured” by increasing ventilation, amongst other measuresamongst other measures

Overall conclusion is that SBS is a complex Overall conclusion is that SBS is a complex phenomenon with a number of causes, phenomenon with a number of causes, possibly influenced by the victims reaction possibly influenced by the victims reaction and attitude to the working environmentand attitude to the working environment

Leptospirosis - Weil’s Leptospirosis - Weil’s DiseaseDisease

An infectious jaundice with symptoms An infectious jaundice with symptoms of fever, jaundice, liver enlargement, of fever, jaundice, liver enlargement, haemorrhages and feverish relapseshaemorrhages and feverish relapses

Causative organism is a spirochaete Causative organism is a spirochaete called called Leptospira icterohaemorrhagiaeLeptospira icterohaemorrhagiae

Rats are the primary cause of the Rats are the primary cause of the diseasedisease

Found in the kidneys of rats and is Found in the kidneys of rats and is excreted in urineexcreted in urine

Leptospirosis - Weil’s Leptospirosis - Weil’s DiseaseDisease

There is evidence that the spirochaete There is evidence that the spirochaete can pass through intact skincan pass through intact skin

Persons at risk include:Persons at risk include:– canal workerscanal workers– sewer workerssewer workers– agricultural workersagricultural workers– rat catchersrat catchers– pig workerspig workers– butchers butchers

Leptospirosis - Weil’s Leptospirosis - Weil’s DiseaseDisease

Primary control is through systematic Primary control is through systematic destruction of rats in infested areasdestruction of rats in infested areas

Prophylactic immunisation offers the best Prophylactic immunisation offers the best solution in sewer workerssolution in sewer workers

All “at risk” workers should carry a card All “at risk” workers should carry a card warning of the dangers, stressing personal warning of the dangers, stressing personal cleanliness and hygiene, explaining the cleanliness and hygiene, explaining the need for protective clothing and alerting need for protective clothing and alerting doctors to the possibility of the diseasedoctors to the possibility of the disease

Leptospirosis - Weil’s Leptospirosis - Weil’s DiseaseDisease

It is essential that people subject to It is essential that people subject to potential risk are:potential risk are:– aware of the causes and symptomsaware of the causes and symptoms– given instruction in suitable first-aid given instruction in suitable first-aid

precautions (e.g. covering existing skin precautions (e.g. covering existing skin wounds, cleaning and disinfecting all fresh wounds, cleaning and disinfecting all fresh wounds), notifying a GP if `flu-like wounds), notifying a GP if `flu-like symptoms occur and notifying public symptoms occur and notifying public authorities if rat infestation is noticed in a authorities if rat infestation is noticed in a work areawork area

FungiFungi Cause ill-health through inhalation of contaminated Cause ill-health through inhalation of contaminated

dust. Examples include:dust. Examples include:– Extrinsic Allergic Alveolitis is a type of pneumoconiosis of Extrinsic Allergic Alveolitis is a type of pneumoconiosis of

biological origin caused by exposure to organic dusts of biological origin caused by exposure to organic dusts of vegetable and animal originvegetable and animal origin

– Bagassosis is a similar disease to farmer’s lung resulting Bagassosis is a similar disease to farmer’s lung resulting from exposure to spores present in the cellulose fibres of from exposure to spores present in the cellulose fibres of cane-sugar after the sugar has been extractedcane-sugar after the sugar has been extracted

– Aspergillosis is an all-embracing term to describe the Aspergillosis is an all-embracing term to describe the types of extrinsic allergic Alveolitis (asthma) caused by types of extrinsic allergic Alveolitis (asthma) caused by the spores of the Aspergillus fungus, found as a mould on the spores of the Aspergillus fungus, found as a mould on cellulosic fibres such as hay, straw, jute, flax, hemp, cellulosic fibres such as hay, straw, jute, flax, hemp, sugar-canesugar-cane

FungiFungi Farmer’s Lung is a specific disorder caused by Farmer’s Lung is a specific disorder caused by

exposure to spores from mouldy hay.exposure to spores from mouldy hay.– The disease is result of hypersensitivity due to an The disease is result of hypersensitivity due to an

antigen present in the dust.antigen present in the dust.– Symptoms are often mistaken for `flu, with extreme Symptoms are often mistaken for `flu, with extreme

shortness of breath on exertionshortness of breath on exertion– Recovery is swift following removal of the individual Recovery is swift following removal of the individual

from the dust sourcefrom the dust source– However, with seasonal exposures the disease However, with seasonal exposures the disease

becomes chronic, leading to pulmonary fibrosis, becomes chronic, leading to pulmonary fibrosis, emphysema and bronchiectasis, by which time it emphysema and bronchiectasis, by which time it may be irreversiblemay be irreversible

HepatitisHepatitis

Those at risk include doctors, surgeons, Those at risk include doctors, surgeons, nurses and portersnurses and porters

Infection amongst health workers is a result Infection amongst health workers is a result of contact with blood or excreta of patients of contact with blood or excreta of patients suffering from viral hepatitis or in whom the suffering from viral hepatitis or in whom the disease is still in its incubation stagedisease is still in its incubation stage

Porters and refuse disposal are at risk from Porters and refuse disposal are at risk from carelessly discarded syringes and other carelessly discarded syringes and other sharps - the problem is becoming worse sharps - the problem is becoming worse with the increase in drug addictionwith the increase in drug addiction

HepatitisHepatitis

Course of disease is similar to Weil’s Disease, Course of disease is similar to Weil’s Disease, but is usually much less severe and normally but is usually much less severe and normally self-limiting with recovery in about 6 weeksself-limiting with recovery in about 6 weeks

In about 5% of cases, chronic infectious In about 5% of cases, chronic infectious hepatitis follows, leading to cirrhosis and hepatitis follows, leading to cirrhosis and possibly deathpossibly death

Persons exposed to risk can be protected with Persons exposed to risk can be protected with injections of gammaglobulininjections of gammaglobulin

In all cases, protective disposable gloves should In all cases, protective disposable gloves should be worn and hands and arms washed regularly be worn and hands and arms washed regularly with disinfectantwith disinfectant

AIDSAIDS Acquired Immune Deficiency SyndromeAcquired Immune Deficiency Syndrome Caused by Human Immunodeficiency Virus Caused by Human Immunodeficiency Virus

(HIV), which attacks the immune system(HIV), which attacks the immune system Virus is found in most body fluids but is Virus is found in most body fluids but is

delicate and relatively easy to kill with delicate and relatively easy to kill with heat and chemicalsheat and chemicals

It has low infectivity and transmission is It has low infectivity and transmission is thought to be more likely with repeated thought to be more likely with repeated exposure to infection rather than to a exposure to infection rather than to a single contactsingle contact

AIDSAIDS Occupational risk comes from accidental Occupational risk comes from accidental

inoculation or contamination of a cut or inoculation or contamination of a cut or abrasion with blood or body fluids of an abrasion with blood or body fluids of an infected personinfected person

Doctors, nurses, dentists, laboratory and Doctors, nurses, dentists, laboratory and hospital staff are at some risk, since they hospital staff are at some risk, since they may come into close contact with body fluidsmay come into close contact with body fluids

Other workers possibly at risk might include Other workers possibly at risk might include community, welfare, custodial and community, welfare, custodial and emergency service workers and first aidersemergency service workers and first aiders

AIDSAIDS Many of the precautions taken against other Many of the precautions taken against other

infections, especially Hepatitis B, will be infections, especially Hepatitis B, will be equally effective against HIV. They include:equally effective against HIV. They include:– Prevention of puncture wounds, cuts and Prevention of puncture wounds, cuts and

abrasions in the presence of blood and body abrasions in the presence of blood and body fluids; and the protection of existing wounds and fluids; and the protection of existing wounds and skin lesionsskin lesions

– Control of surface contamination by containment Control of surface contamination by containment and disinfectionand disinfection

– Safe disposal of contaminated waste, especially Safe disposal of contaminated waste, especially sharpssharps