To minimise the risk of infection, gardeners should:
• Open the bag with care to avoid inhalation of airborne potting mix.
• Moisten the contents to avoid creating dust.
• Wear gloves to avoid transferring the potting mix from hand to mouth.
• Wash hands after handling potting mix, even if gloves
Epidemic Measures
An outbreak is defined as more than one case associ-ated in time and place.
When an epidemic occurs, activate Displan which allows for investigation for common source of infection and resultant action as indicated.
* Guidelines refers to Guidelines for the Control of Legionnaires’ Disease, 1989.
Leprosy (Hansen’s Disease)
Victorian Statutory Re q u i re m e n t
Group B notification.
Infectious Agent
Mycobacterium leprae.
Clinical Features
It is a chronic bacterial infection involving the cooler body tissues, skin, superficial nerves, nose, pharynx, larynx, eyes and testicles.
Skin lesions may occur as pale, anaesthetic macular lesions or erythematous infiltrated nodules.
Neurologic disturbances are manifested by nerve infiltration and thickening with anaesthesia, neuritis, paraesthesia and trophic ulcers.
The disease is divided clinically and by laboratory tests into two overlapping types: lepromatous and tuberculoid.
The lepromatous type is progressive with nodular skin lesions, slow symmetric nerve involvement, numerous acid-fast bacilli in the skin lesions and a negative lep-romin skin test.
The tuberculoid type is benign and non-progressive with localised skin lesions, asymmetric nerve involvement, few bacilli present in the lesions and a positive lepromin skin test.
Leprosy should always be suspected in any patient with an undiagnosed peripheral neuropathy or chronic skin lesions.
Public Health Significance and O c c u r re n c e
It is occasionally seen on routine refugee screening.
The world prevalence is estimated to be between 10 to 12 million cases.
The disease is endemic in tropical and subtropical Asia, Africa, Central and South America, Pacific regions and the USA (Hawaii, Texas, California, Louisiana, Puerto Rico).
Method of Diagnosis
Clinical examination.
Laboratory tests which show:
• The demonstration of acid-fast bacilli in scrapings from skin or the nasal septum.
• A typical histologic picture in a biopsy of skin or of a thickened involved nerve.
Re s e r voi r
Humans.
Mode of Transmission
The mode of transmission is not clearly established. The disease is probably transmitted by aerosol with a high subclinical rate of infection.
Household and prolonged close contact seem to be important.
In cases of children under one year of age, transmission is probably transplacental.
Incubation Period
The incubation period is difficult to determine.
It probably ranges from nine months to 20 years; on average four years, for tuberculoid leprosy and eight years for lepromatous leprosy.
Period of Communicability
Leprosy is not infectious after three months of continuous treatment with dapsone or clofazimine, or after two to three weeks of treatment with rifampicin.
Susceptibility and Resistance
Infection among close contacts of leprosy patients is frequent, but clinical disease occurs only in a small proportion.
Control of Case
No isolation is required for cases of tuberculoid leprosy;
contact isolation is required for cases of lepromatous leprosy.
Nasal discharges of infectious patients should be concurrently disinfected.
Tre a t m e n t
The minimal regimen recommended by WHO for lepro-matous leprosy is rifampicin, dapsone and clofazimine and, recently, ofloxacin.
The treatment should be continued until skin smears become negative for at least two years.
For tuberculoid leprosy, the recommended regimen is rifampicin and dapsone for a period of six months (for detailed treatment see Control of Communicable Dis-eases in Man by Benenson).
Control of Contacts
Investigation of contacts and source of infection.
Early detection and treatment of new cases.
Prophylactic BCG has resulted in a considerable reduc-tion in the incidence of tuberculoid leprosy among contacts in some trials.
Epidemic Measures
Not applicable.
L e p t o s p i r o s i s
Victorian Statutory Re q u i re m e n t
Group B notification.
Infectious Agent
Leptospira species (many serovars). In Victoria, the most common serovar is Leptospira borgpetersenii var hardjo.
Clinical Features
Clinical features include fever, headache, chills, myalgia and red eyes.
Other manifestations are diphasic fever, rash, meningitis, haemolytic anaemia, haemorrhage into skin and mucous membranes, hepato-renal failure, jaundice, mental confusion/depression, pulmonary involvement and haemoptysis.
Clinical illness lasts a few days to three weeks or more.
Recovery, if untreated, may take months.
Public Health Significance and Oc c u r re n c e
It is a zoonotic disease that needs exposure to water contaminated by animal urine, or contact with tissues or urine of infected animals.
It is an occupational hazard for farmers, sewer workers, miners, dairy and abattoir workers and fish workers, and a recreational hazard to bathers, campers and sports-men.
Many cases have arisen in herringbone-style milking sheds.
Method of Diagnosis
See checklist at the end of this section.
Laboratory diagnosis:
• Rising titres on repeated serology.
• Take blood during acute illness and two to three weeks later.
• Isolate leptospires:
– Blood (days 0 to 7).
– CSF (days 4 to 10) lumbar puncture.
– Urine (after 10 days).
Repeated blood cultures, into specific media during the first week of disease are usually successful.
Preferably take blood cultures before antibiotic therapy is commenced.
Re s e r voi r
Many animal hosts. In Victoria, cows, rats and pigs.
Mode of Transmission
It can be transmitted by:
• Contact of skin, especially if abraded, or of mucous membranes with water, moist soil or vegetation con-taminated with urine of infected animals.
• Direct contact with urine or tissues of infected animals.
• Ingestion of foods contaminated with urine of infected rats.
• Inhalation of droplet-aerosols of contaminated fluids.
Incubation Period
Usually 10 to 12 days (the range is four to 19 days).
Period of Communicability
Leptospires may be excreted in the urine of animals for one month usually (but up to 11 months has been reported).
Susceptibility and Resistance
Immunity to the specific serovar follows infection, but may not protect against infection with a different serovar.
Control of Case
• Isolate the case with blood/body fluid precautions.
• Disinfect articles soiled with urine.
• Use antibiotic treatment: penicillin, doxycycline or amoxycillin.
Investigation
• Ascertain occupational exposure.
• Seek the source of the infection; for example, contact with contaminated water, farm or domestic animals, rodent infestations.
• Inform the Department of Natural Resources and Energy.
Control of Contacts
No human vaccine is available.
Search for exposure to infected animals and potentially contaminated waters.
Control of Environment
Recognise potentially contaminated waters and soil, and drain such waters when possible.
Preventive Measures
• Educate the public on modes of transmission to avoid swimming or wading in potentially contaminated waters, and to use proper protection when work requires such exposure.
• Consult the Department of Natural Resources and Energy on herd immunisation.
• Prevent the contamination of accommodation, working and recreational areas.
Epidemic Measures
• Seek source of infections and eliminate contamination or prohibit use of infected waters.
• Search for industrial and occupational source.
Question Answer Score A. Has the patient:
• Headache of sudden onset?
• Fever?
• If yes, is the temperature 39˚C or more?
• Red eyes (bilateral)?
• Meningism?
• Muscle pains (especially calf muscles)?
• Are all three features (red eyes, muscle pains and meningism) present together?
• Jaundice?
• Albuminuria or nitrogen retention?
B. Epidemiological factors:
• Has there been contact with animals at home, work, leisure, or in travel, or contact with known (or possibly) contaminated water?
C. Bacteriological laboratory findings:
• Isolation of leptospires in culture—diagnosis certain.
• Positive serology—leptospirosis endemic:
Single positive, low titre (that is, < 200).
Single positive, high titre (that is, > 400).
Paired sera, rising titre ( ≥ 4 fold).
• Positive serology—leptospirosis not endemic:
Single positive, low titre (that is, < 200).
Single positive, high titre (tha is, > 400).
Paired sera, rising titre ( ≥ 4 fold).