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It is inicresting to notę that because of improvcd persona! and cnvironmcntal hygicnc standnrds lcptospirosis is not now common in miners, sewer workers and fish cleanors who were at one time eommonly infcctcd.

The adoption of hygicnc precautions - a sine qun non for all zoonoses - the reduction of the rat population and the prompt treat-ment of clinical cascs in man have rcduccd the hazard of leptospirosis.

Listeriosis

Listeria nionoc\fto$cncs is a ubiquitous organ-isrńTTt can be shed from the intestinc in animals (domestic and wijd) and man without any~apparent clinical symptoms. Most human cases are associated with sources other than animals. Infection is mainly neonatal, but direct contact with infective materiał e.g. aborted fetuses, contaminated soil, etc., as wcl! as ingestion and inhalation may also be modes of transmisśion. In a few cases infection has occurrcd in man as a resułt of eating infectcd meat. The organism has becn morę frequently isolated from the faeccs of abattoir wori<ers than from any other classes of people, although the exact reason for this is not under-stood.

As in animals, the disease łakes the form of an encephalitis or abortioo, occurring in adults and in the neonatal period. Mortality rates may bc as high as 42%.

Louping ill

An incidence of louping ill infection of 8.3% was dctectcd in Scottish abattoir workers in 1966. The fręguency of cuts and other abra-sions sustaincd by abattoir Staff undoubtedly predisposes to this infection. It is caused by an arbovirus and transmitted by_ticks (lxodcs ricinus, Ipersatcalns, I. cookei, R/tipiccphalus appendiculntns). Louping ill is an acute en-cephalomyelitis of sheep which is occasionaJTy transmitted to man by the bite of an infective tick or by the consumption of milk from infected animals.

Avian psittacosis and ornithosis (chlamydiosis) (parrot fevcr)

Both diseases are transmissible to man, psittacosis from birds of the psittacine order (parakcets, parrots. etc.) and ornithosis from birds other than psittacincs. The disease is world wide in distribution and affects a wide varicty of birds. Among domestic poultry it is most common in ducks, turkeys and pigeons, which are the main sources of human infection.

Persons may bccome infected morę than once and, while the disease is usually mild, it can be severe. Human infection occurs by inhalation following exposure to infective aerosols or dust-infected bird droppings. Chlamydm psiltoci may be responsible for cases of conjunctivitis in persons working in the poultry industry, especially in dust-ladcn atmospheres.

The first recorded outbreak of ornithosis in the UK occurred in the. winter and spring of 1979-80 and was associated with commercially reared ducks, some cases involving workers in a duck processing plant and others occurring in 15 out of 46 veterinary surgeons attending a training course on the supervision of poultry processing plants.

A survey of workers in the Brilish duck industry has indicated a past exposure to infection ratę (based on results of complement fixation (CF) tests on blood samples) of 11%. The workers employed on evisceration lines in duck processing plants showed the highest titres to the CF test.

Cases of ornithosis originating from ducks

have also occurred in Czechoslovakia and

• • *

Denmark. In the former country it was said that covering the evisceration lines and improving the ventilation by the installation of extractor fans had solved the problem.

While the annual number of human cases arising from psittacine birds has been dccreasing sińce the implemenłation of the Importation of Captive Birds Order of 1976, the overaII number of ornithosis cases has been rising.

Symptoms in humans include gas-trointestinal pain and vomiting, headache, insomnia and pneumonia. Mild attacks of the disease may be mistaken for influenza. Recov-ery is usually complete, but convalesccnce may be prolonged.

The disease responds well to tetracyclines and antibiotic prophylaxis with chlor-tctracycline is advocatod for the control of the disease. Satisfactory standards of ventilation and the prevention of dusty environmcnts are of value, as are dust masks where necessary.

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