Brucellosis | 7 Prevention

7 Prevention

Detection and destruction of infected animals has to be implemented. There is a vaccine for animals, but not for humans. Pasteurisation of milk and avoidance of cheese made from potentially contaminated milk are important. Gloves are to be used when working with potentially infected animals and their secretions.

Note: uveitis

Uveitis is a general term for inflammatory disorders of the uveal tract. Anterior uveitis is the term which encompasses iritis and iridocyclitis. Posterior uveitis is the preferred term for choroiditis and chorioretinitis. In the non-granulomatous form, the onset is characteristically acute, with pain, injection, photophobia and blurred vision. There is a circumcorneal flush caused by dilated limbal blood vessels. Fine white depositis on the posterior surface of the cornea can be seen with a slitlamp. The pupil is small and there may be a collection of fibrin with cells in the anterior chamber. If posterior synechiae are present, the pupil will be irregular in shape. In granulomatous uveitis, the onset is usually insidious. Vision gradually becomes blurred and the affected eye becomes diffusely red with circumcorneal flush. Pain is minimal and photophobia is less marked than in the non-granulomatous form. Fresh active lesions of the choroid and retina appear as yellowish-white patches seen hazily with the ophthalmoscope through the cloudy vitreous. As healing progresses, the vitreous haze lessens and pigmentation occurs gradually at the edges of the yellowish-white spots. In the healed stage there is usually considerable pigment deposition. If the macula is not involved, recovery of central vision is complete. The patient is usually not aware of the scotoma in the peripheral field corresponding to the scarred area.

There are various causes, including a number of infectious diseases, but also auto-immune disorders. A wider range of diagnoses must be considered for patients in developing countries.

Parasitic: toxoplasmosis, Toxocara infection (infection by the larva of a canine nematode), cysticercosis (larval Taenia solium), Onchocerca volvulus

Bacterial : syphilis, tuberculosis (with granulomata on the retina), leprosy, bartonellosis with cat scratch disease, leptospirosis, Q fever, Lyme disease, brucellosis

Viral: CMV (think of HIV), herpes simplex, HTLV-1, measles

Fungi: Candida (usually panophthalmitis), cryptococcosis, histoplasmosis

Non-infectious causes include:

Sarcoidosis

Systemic lupus erythematosus (i.e vasculitis).

Traumatic and sympathetic ophthalmia.

Reiter’s syndrome. In addition to anterior uveitis, conjunctivitis, urethritis, balanitis, oral ulcers, low fever and joint pain can also be present. There is often a recent history of infected sexual contact (Chlamydia trachomatis) or enteritis. Hyperkeratotic lesions on the palms of the hands and soles of the feet resembling pustular psoriasis can occur.

Associated with juvenile rheumatoid arthritis, Still’s disease.

Associated with ankylosing spondylitis – HLA B27 (Bechterew’s disease).

Behçet’s syndrome.

Vogt-Koyanagi-Harada syndrome (uveo-encephalitis) with cutaneous and neurological symptoms in addition to ocular lesions (birdshot retinopathy).

Unknown cause, e.g. heterochromic uveitis (Fuch’s cyclitis).

Expert advice from an experienced ophthalmologist and a specialist in internal diseases is essential to save the patient's sight. If for example toxocariosis of the eye were to be treated with anthelminthics only, the larva would die and release a large quantity of antigen. This would cause the intra-ocular inflammation to increase, resulting in cloudiness of the vitreous humour and total blindness. Vitrectomy and steroids should therefore constitute part of the treatment.