Infections to the eye Flashcards

Question

what is leptospira

Answer 1

Common infection of rats Systemic infection of the rat, excreted in faeces and urine Proximity of rats to water often means water sources are colonised Rivers, streams country parks, lakes Swimming in contaminated water can lead to infection Swallowing of water, contamination of mucous membranes or through breaks in the skin 2-4 week incubation period, clinical multi-organ infection occurs, known as Weil’s disease Liver infection leads to cell destruction and jaundice Evidence of infection is seen in the eyes where bleeding, yellowing and vision impairment manifest

Answer 2

leptospira

Answer 3

Histology shows infiltration of the eye by numerous corkscrew-shaped (Spirochete) bacteria together with cellular invasion Leptospira interrogans Severe immune response Can severely impair vision and lead to blindness Treated with doxycycline or penicillin

Answer 4

Syphilis is a sexually transmitted infection, increasing in prevalence Primary syphilis - Flat ulcer appears on genitalia Corkscrew organisms called Treponema pallidum 50% of cases heal spontaneously Secondary syphilis – Dissemination of organism from primary ulcer throughout the body causing a widespread rash – may present with a wide range of symptoms Tertiary syphilis – Continuation of secondary stage alongside infection of neurons and a severe immune reaction – neurological symptoms such as Tabes Dorsalis and general paralysis of the insane Chronic persistent infection of women Can lead to stillborn births Can result in birth of child with irreversibly damaged eyes Retinitis Interstitial keratitis  can lead to blindness and potentially death

Answer 5

Bacteria Inability to produce energy Parasitise cells Grow and multiply inside host cells Use host cells to produce energy allowing function of enzymes Common Associated with STI Can be aymptomatic 10% of women subclinical infection which can be dangerous to child being born Three forms of infection Genitourinary Pulmonary Ocular Develops after infection from mother at birth (similar to N. gonorrhoeae) A kerato conjunctivitis occurring at 4-7 days of age

Answer 6

Most common but treatable cause of blindness in the world Thickening of eyelids, inner eyelid becomes abrasive Untreated or repeated infection leads to scarring of the inner eyelid, leading to distortion Eyelid everts, forcing eyelashes to irritate and damage the eye Scratching of eye leads to secondary infections and blindness

Answer 7

Can’t grow on agar Chlamydia grown on tissue cultures Infected cells contain Chlamydia inclusion bodies Stained with antibody linked to fluorescent dyes Very preventable Infection treated with azithromycin Antibiotic eye drops also recommended

Answer 8

Mild infection caused by Rubella virus – German measles Previously very common – now covered by vaccines Contracted as a droplet infection Incubation period 14-21 day Onset – low grade fever and catarrh for 2 days Prodromal symptoms – non-specific symptoms followed by classical symptoms Rash – maculopapular, begins on face and neck General lymphadenopathy Some cases mild with no rash Many cases sub-clinical – produce lifetime immunity with no symptoms

Answer 9

Very mild or asymptomatic infection in children Symptoms usually worse in adults Extremely serious if infected whilst pregnant Miscarriage or congenital rubella syndrome (CRS)

Answer 10

Virus can pass across the placenta and infect the foetus First trimester – 90% will suffer Rubella syndrome Second trimester – 20% Third trimester – quite rare Whole host of symptoms Mental incompetence Microcephaly Cerebral palsy Deafness Congenital heart disease High proportion of miscarriage

Answer 11

In womb, every pore, gland and fluid exudes virus – completely takes over Foetus surrounded by a cloud of virus Exist in a cocoon of perpetual infection

Answer 12

Rubella syndrome includes cataracts and glaucoma Irreversible Very common in CRS Preventable MMR vaccine

Answer 13

A group of 42 viruses sharing a common structure Electron microscopy 12 triangular plates in geometric pattern Stalks from each corner Proteins in white are same across all 42 strains Hexons – Six proteins touching each white ball Pentons – Corners can only house 5 proteins Proteins in black differ – 42 different forms Penton base with fiber Infection from one will not give immunity to others

Answer 14

Three different groups in pathogenesis First group – More severe form of a cold Common cold Trivial infection - 2/3 days No temperature/fever Infection of nasal passages – mucus produced – irritates throat Symptoms from immune response Adenovirus colds Respiratory and influenza like symptoms 7-8 days Glands swell Infection of throat and nasal passages

Answer 15

Three different groups in pathogenesis First group – More severe form of a cold Common cold Trivial infection - 2/3 days No temperature/fever Infection of nasal passages – mucus produced – irritates throat Symptoms from immune response Adenovirus colds Respiratory and influenza like symptoms 7-8 days Glands swell Infection of throat and nasal passages Mild infections – troops often vaccinated against

Answer 16

Shipyard Eye’ Complaint in shipyard workers and metal workers Eye infection with no pharyngitis Intense inflammation in one or both eyes No infection in families Atmosphere full of microscopic metal particles Cause trauma in the eye Contact with adenovirus infected patient causes spread Problem in eye clinic Examination involves slight damage to eye Patient with Shipyard Eye can easily transmit to other patients Eye  throat Infections must run course

Answer 17

Poxvirus Common in young children Causes small bladder-like lesions on the neck, arms or legs If opened – no pus Usually painless Can last up to 2 years Eventually recognised and removed by the body

Answer 18

Occasionally occurs on eyelids Look like a stye Unlike staphylococci, not solid Almost balloon like Best to leave alone, reversible

Answer 19

Material from lesion does not contain pus Unlike staphylococci Under the electron microscope: Large brick-shaped virus particles No treatment, should resolve spontaneously

Answer 20

Emerging evidence that it may cause conjunctivitis Important to continue all safety measures during examinations Mucous membranes of the eye considered a pathway to infection People with glasses 2-3 times less likely to contract

Answer 21

Herpesviridae – 8 known to infect humans Herpes simplex (HSV-1) – most common Primary infection usually children 6 months - 5 years old Acquired by contact from patients or carriers Produces a blister/ulcer on the mouth (cold sore), face etc. Virus retreats to ganglia – can periodically reactivate Often passed to children – when adults secreting virus Cold sore and kissing newborn

Answer 22

Lesion normally forms on lips – very itchy Can be transferred by rubbing/scratching to other skin surfaces, e.g. near the eye Secondary lesions Can also be transferred directly to the eye

Answer 23

Can cause Conjunctivitis Dendritic ulcers Keratitis Blindness Most common infective cause of blindness in high income countries Corneal graft may be required

Answer 24

Can be treated with aciclovir Analogue to nucleotides Inactivates viral DNA replication Very potent Non-toxic No resistance Affects majority of herpesviridae Available over the counter at pharmacists Initial ‘tingle’ 48 hours prior Treatment will abort infection

Answer 25

Herpesviridae Spread by inhaling virus Dried from lesions or as droplets Incubation period of 14-21 days Manifests in outbreak of respiratory symptoms and rash Face and in hair, central body more than hands and feet Vaccine available, not used in UK Immunocompromised may be offered Can cause haemorrhagic chicken pox

Answer 26

Individual lesions are like blisters Very itchy Following recovery, virus remains in the dorsal root ganglia for life Can also retreat to other ganglia Doesn’t usually reoccur

Answer 27

In later life, virus is reactivated to produce shingles Multiplies within the nerves Intensely painful rash which follows the nerve Manifests on skin associated with tight clothing No treatment for it Aciclovir can reduce symptoms

Answer 28

Occasionally can reactivate from facial ganglion (trigeminal nerve) Large rash across face – demarcation due to infection of specific nerve From here can spread to eye Very damaging but quite rare Virus can travel along the optic nerve to the brain to cause encephalitis

Answer 29

Some free-living amoebae can cause keratitis – quite rare Acanthamoeba Usually associated with contact lenses which have not been cleaned with sterile saline solutions – enter after trauma to eye Amoebae found in plain tap water Must not use for cleaning contact lens or equipment for examining eyes Very difficult to treat

Answer 30

Microscopic African worm living in freshwater rivers 99% of infected people live in 30 countries across sub-Saharan Africa 37 million people in East and Central Africa are carriers 800,000 blind Eaten by simulian flies and transferred to humans through insect bites Parasite multiplies at site of bite to cause swelling, nodules protect parasite from immune response Parasite produce embryonic larvae which migrate to all organs of the body

Answer 31

Migrating larvae die and initiate an intense immune response In skin, intense itching, swelling and inflammation Can penetrate all areas of the eye Often migrates to surface of the cornea causing keratitis Eventually leads to blindness River blindness

Answer 32

Can occur in >90% of adults in some African tribes Younger generations required to lead infected generation Proximity means high likelihood of passing on the parasite Also found in Yemen, Brazil and Venezuela No vaccine or medication to prevent infection Best option is prevention Ivermectin can kill larvae but not adult worms (6-12 months)

Answer 33

Parasitic roundworm of cats and dogs, eggs excreted in faeces Spread to humans through ingestion of eggs Children in parks Larvae can migrate throughout body causing a severe allergic reaction Parasitic larvae can encyst within the eye Can form a granuloma, and cause a peripheral eosinopimulia Mass (granuloma) often confused with malignant retinoblastoma Loss of vision over days or weeks Damage is permanent, can result in blindness