Infectious Disease Flashcards
Gram positive cocci?
StaPhylococci
StrePtococci
(including enterococci)
Gram negative cocci?
N for negative
- Neisseria meningitidis
- Neisseria Gonorrhoeae
- Also Maroxella
Gram +ve rods? (Bacilli)
ABCDL
- Actinomyces
- Bacillus antracis (anthrax)
- Clostridium
- Diphtheria
- Listeria monocytogenes
Gram -ve rods?
Everything that is not the other three
- Pseudomonas
- E.coli
- Enterobacter
- Klebsiella
- Salmonella
- Shigella, Proteus
- Bordatella pertussis
- Haemophilus
- H Pylori
- Legionella
- Camplyobacter
Miscellaneous/Poorly staining species?
Intracellular Bacteria
- Chlamydia
- Rickettsia
- Borella
Poorly Staining
- Mycoplasma
- Legionella
- Helicobacter
Acid Fast Strain
- Mycobacteria
- Nocardia
Antibiotics with anti-anaerobic activity?
- Penicillins
- Cephalosporins (except ceftazidime)
- Erythromycin
- Metronidazole
- Tetracycline
Antibiotics with no anti-anaerobic activity?
- Gentamicin
- Ciprofloxacin
- Ceftazidime
Incubation periods?
Less than 1 week
- Scarlet fever
- Influenza
- Diphtheria
- Meningococcus
1 - 2 weeks
- Malaria
- Measles
- Dengue fever
- Typhoid
2 - 3 weeks
- Mumps
- Rubella
- Chickenpox
Longer than 3 weeks
- Infectious mononucleosis
- Cytomegalovirus
- Viral hepatitis
- HIV
Live vaccines?
- BCG
- measles, mumps, rubella (MMR)
- oral polio
- oral typhoid
- yellow fever
Other vaccines (non-live)?
Whole killed organism/inactivated
- Rabies
- Influenza
Detoxified Exotoxins
- Tetanus
Fragment/Extracts of Organism/Virus
- Diphtheria
- Pertussis
- Hepatitis B
- Meningococcus, Pneumococcus, Haemophilus
Other
- Cholera - inactivated strains of vibrio cholerae along with recominant B-subunit of cholera toxin
- Hep B - contains HBsAg absorbed onto aluminium hydroxide adjuvant, prepared from yeast cells
Post-exposure prophylaxis?
Hep A
- Human normal immunoglobulin (HNIG) or hep A vaccine
Hep B
- If from HBsAg +ve source
- If exposed peron is a known responder to HBV vaccine then –> booster dose.
- If in process of being vaccinaed or non-responder –> hep B immune globulin (HBIG) and the vaccine
- If from unknown source
- Consider booster dose of HBV vaccine. If non-responder give HBIG + vaccine
- If in process of being vaccinated then accelerate course of HBV vaccine
Hep C
- Monthly PCR - if seroconversion then interferon +/- ribavirin
HIV
- PEP - Tenofovir, Emtricitabine, Lopinavir and Ritonavir - ASAP, up to 72 hours after, continue for 4 weeks
- Serological testing at 12 weeks
Varicella Zoster
- VZIG for IgG negative pregnant women/immunosuppressed
Tetanus vaccine?
- Given at: 2 months, 3 months, 4 months, 3-5 years, 13-18 years
- High risk wounds –> give IM human tetanus immunoglobulin (irrespective of whether 5 doses of vaccine given)
- High risk wounds = compound fractures, delayed surgical intervention, significant degree of devitalised tissue
- If vaccination Hx unknown or incomplete - dose of tetanus vaccine along with IM human tetanus Ig for high risk wounds
Tetanus?
Cause
- Tetanospasmin endotoxin released by clostridium tetani
- Teatnus spores in soil –> introduced by a wound
- Prevents release of GABA
Features
- Prodrome fever, lethargy, headache
- Trismus (lockjaw)
- Risus sardonicus
- Opisthotonus (arched back, hyperextended neck)
- Spasms (e.g. Dysphagia)
Management
- Supportive therapy including ventilatory support and muscle relaxants
- Intramuscular human tetanus Ig for high-risk wounds
- Metronidazole cover
Features of HIV seroconversion?
- Sore throat
- Lymphadenopathy
- Malaise, myalgia, arthralgia
- Diarrhoea
- Maculopapular rash
- Mouth ulcers
- Rarely meningoencephalitis
Man returns from trip abroad with maculopapular rash and flu-like illness - think HIV seroconversion
Immunological changes in progressive HIV?
- Reduction in CD4 count
- Increase B2-Microglobulin (IBM)
- Decrease IL-2 production (DIL=DELL) –> IBM & DELL
- Polyclonal B-cell activation
- Decreased NK cell function
- Decreased delayed hypersensitivity responses
Vaccines that can be used in HIV if CD4 >200, and contraindicated?
If CD4 >200
- MMR
- Varicella
- Yellow fever
Contraindicated
- Cholera (CVD103-HgR)
- Influenza-intranasal
- Poliomyelitis-oral (OPV)
- Tuberculosis (BCG)
Everything else can be used in all HIV infections
Diarrhoea in HIV?
Can be due to the virus itself (HIV enteritis) or opportunistic infections
- Cryptosporidium + other protozoa (most
common) - Cytomegalovirus
- Mycobacterium avium intracellulare - CD4 <50, deranged LFTs
- Giardia
Cryptosporidium - incubation 7 days. Acid fast stain (Ziehl-Neelsen) may reveal characteristic red cysts.
Factors which reduce vertical HIV transmission?
- Maternal antiretroviral therapy - should be commenced between 28-32 weeks and continue intrapartum
- Mode of delivery (caesarean section) - zidovudine infusion commenced 4 hours prior to start of section
- Neonatal antiretroviral therapy - zidovudine orally for 4-6 weeks
- Infant feeding (bottle feeding)
Kaposi’s sarcoma?
- Caused by HHV-8 (Human Herpes Virus 8)
- Presents as purple papules or plaques on the skin or mucosa (e.g. Gastrointestinal and respiratory tract)
- Skin lesions may later ulcerate
- Respiratory involvement may cause massive hemoptysis and pleural effusion
- Radiotherapy + resection
PCP pneumonia?
- Pneumocystis jiroveci is an unicellular eukaryote, generally classified as a fungus but some authorities consider it a protozoa
- PCP is the most common opportunistic infection in AIDS
- All patients with a CD4 count < 200/mm³ should receive PCP prophylaxis
Features
- Dyspnoea, dry cough, fever
- Very few chest signs
- Extrapulmonary (rare) - hepatosplenomegaly, lymphadenopathy, choroid lesions
Ix
- CXR - bilateral interstitial pulmonary infiltrates, may be normal
- Exercise-induced desaturation
- Sputum often fails to show PCP - BAL often needed for silver stain
Mx
- Septrin
- IV pentamidine in severe cases
- Steroids if hypoxic
Biliary disease and pancreatitis in HIV?
Biliary Disease
- Sclerosing cholangitis due to CMV, cryptosporidium and microsporidia
Pancreatitis
- Secondary to anti-retroviral tx (didanosine)
- Opportunistic infections (CMV)
Meningitis CSF summary?
Summary of streptococci?
Alpha Haemolytic Streptococci
- Strep pneumoniae - pneumonia, meningitis, otitis media
- Strep viridans - endocarditis
Beta Haemolytic Streptococci
-
Group A
- Strep pyogenes - impetigo, cellulitis, nec fascitis, pharyngitis/tonsillitis
- Immunological reactions can cause rheumatic fever or post-strep glomerulonephritis
- Erythrogenic toxins cause scarlet fever
- Penicillin is abx of choice
-
Group B
- Strep agalactiae - nenonatal meningitis and septicaemia
Staphylococcal toxic shock syndrome?
- Fever: temperature > 38.9ºc
- Hypotension: systolic blood pressure < 90 mmHg
- Diffuse erythematous rash
- Desquamation of rash, especially of the palms and soles
- Involvement of three or more organ systems: e.g. Gastrointestinal (diarrhoea and vomiting), mucous membrane erythema, renal failure, hepatitis, thrombocytopenia, CNS involvement (e.g. Confusion)
Severe systemic reaction to staphylococcal exotoxins
Necrotising Fasciitis?
Type 1 = caused by mixed anaesrobes and aerobes (often occurs post-surgery in diabetics)
Type 2 = caused by Strep pyogenes
Features
- Acute onset
- Painful, erythematous lesion develops (cellulitis like)
- Extremely tender over infected tissue
Mx
- Urgent surgical debridement
- IV abx
Listeria monocytogenes?
Gram +ve bacillus
Spreads via contaminated food - unpasteurised dairy products
Can induce miscarriage
Features
- Diarrhoea, flu-like illness
- Pneumonia, meningoencephalitis
- Ataxia and seizures
- CSF may show pleocytosis, with ‘tumbling motility’ on wet mounts
Sensitive to amoxicillin/ampicillin
Anthrax?
- Bacillus anthracis, a Gram positive rod
- Spread by infected carcasses
Features
- Painless black eschar (cutaneous ‘malignant pustule’, but no pus)
- May cause marked oedema
- Can cause GI bleeding
Treat with ciprofloxacin
Legionella?
Legionella Pneumophilia
Colonises water tanks - no person to person transmission
Features
- Flu-like symptoms
- Dry cough
- Lymphopenia
- Hyponatremia
- Deranged LFTs
Diagnosed with urinary antigen
Treat with macrolides (erythromycin)
Leptospirosis (Weil’s disease)?
Questions refer to sewage works, farmers, vets or people who work in an abattoir
Leptospira interrogans (Spirochaete)
Spread classically by contact with infected rat urine
Features
- Fever
- Flu-like symptoms –> WITHOUT PRODUCTIVE COUGH
- Renal failure (seen in 50% of patients)
- Jaundice
- Subconjunctival hemorrhage
- Headache, may herald the onset of meningitis
Mx
- LP to confirm meningeal involvement
- High dose ben pen or doxy
Cause of epiglottitis?
Haemophilus influenzae type B
Lyme disease?
Borreliosis
Caused by 3x species of bacteria belonging to genus Borrelia
- Borrelia burgdorefer - main cause in USA
- Borrelia afzelii and Borrelia garinii - main cause in Europe
Features
- Erythema chronicum migrans (small papule at site of tick bite –> develops into larger annular lesion with central clearing - bulls eye)
- Systemic symptoms - malaise, fever, arthralgia
Later features
- CVS - heart block, myocarditis
- Neurological - cranial nerve palsies, meningitis
- Polyarthritis
Mantoux test?
- Immune mediated type IV hypersensitivity reaction
- Ml of 1:1,000 purified protein derivative (PPD) injected intradermally
- Result read 2-3 days later
- Erythema & induration > 10mm = positive result - this implies previous exposure including BCG
Heaf test?
Classically involves injection of PPD equivalent to 100,000 units per ml to the skin over the flexor surface of the left forearm. It is then read 3-10 days later
- Negative - no induration, 6 minute puncture scars
- Grade 1 - 4-6 puncture sites indurated
- Grade 2 - Confluent puncture sites form indurated ring
- Grade 3 - Extensive induration to form disc (5-10mm)
- Grade 4 - Severe induration >10mm with or without blistering
Grades 1-2 = previous BCG or avian tuberculosis
Grades 3-4 require CXR and follow up
Causes of false negatives for Mantoux/Heaf test?
- Miliary TB
- Sarcoidosis
- HIV
- Lymphoma
- Very young age (e.g. < 6 months)
Treatment for active tuberculosis?
Initial Phase (2 months)
- Rifampicin
- Isoniazide
- Pyrazinamide
- Ethambutol
Continuation Phase (4 months)
- Rifampicin
- Isoniazid
Mangement of latent TB/meningeal TB?
Latent
- Isoniazid alone for 6 months
Meningeal
- Prolonged period of treatment (12 months) with addition of steroids
Side effects of TB treatment?
Rifampicin
- Liver enzyme inducer
- Hepatitis
- Orange secretions
- Flu like symptoms
Isoniazid
- Peripheral neuropathy - prevent with vitamin B6
- Optic neuritis (less common than ethambutol)
- Hepatitis, agranulocytosis
- Liver enzyme inhibitor
Pyrazinamide
- Hyperuricaemia causing gout
- Hepatitis
Ethambutol
- Optic neuritis (visual acuity check before and during)
- Dose adjustment in renal impairment
Streptomycin (resistant TB)
- Vestibular damage –> vertigo and vomiting
- Cochlear damage –> deafness
- Anigioedema
- Nephrotoxicosis
Leprosy (Hansen’s Disease)?
Cause
- Mycobacterium leprae
- Mycobacterium lepromatosis
Features
- Nodular skin lesions
- Erythematous raised plaque like lesions in arms and legs
Can be progressive, causing permanent damange to skin, nerves, limbs and eyes
Mx
- Skin biopsy and needle test
- <5 lesions –> rifampicin and dapsone for 6 months
- >5 lesions –> rifampicin, clofazimine and dapsone 12 months
Features of severe malaria? Complications?
Severe Malaria
- Schizonts on a blood film
- Parasitemia > 2%
- Hypoglycemia
- Temperature > 39 °c
- Severe anemia
- Complications as below
Complications
- Cerebral malaria: seizures, coma
- ARF: blackwater fever, secondary to intravascular hemolysis, mechanism unknown
- Acute respiratory distress syndrome (ARDS)
- Hypoglycemia
- Disseminated intravascular coagulation (DIC)
Management of uncomplicated falciparum malaria?
Strains resistant to chloroquine are prevalent in certain areas of Asia and Africa
WHO 2010 guidelines: artemisinin-based combination therapies (ACTs) as first-line therapy
Examples
- artemether plus lumefantrine
- artesunate plus amodiaquine
- artesunate plus mefloquine
- artesunate plus sulfadoxine-pyrimethamine
- dihydroartemisinin plus piperaquine
Management of severe falciparum malaria?
- A parasite counts >2% will usually need parenteral treatment irrespective of clinical state
- IV artesunate is now recommended by WHO in preference to intravenous quinine (2010 guidelines)
- If parasite count > 10% then exchange transfusion should be considered
- Shock may indicate coexistent bacterial septicemia - malaria rarely causes hemodynamic collapse
Most common causes of non-falciparum malaria?
- Plasmodium vivax - most common, Central America and Indian subcontinent
- Plasmodium ovale - Africa
- Plasmodium malariae
Almost always chloroquine sensitive
In vivax and ovale - use Primaquine to destory liver hypnozoites
Leishmaniasis?
Caused by protozoa Leishmania, spread by sand flies.
Multiplies in monocyctes and macrophages
Incubation period can extend to 10 years
3 types of Leishmaniasis?
-
Cutaneous Leishmaniasis
- Caused by Leishmania tropica or Leishmania mexicana
- Crusted lesion at site of bite
- May be underlying ulcer
-
Mucocutaneous Leishmaniasis
- Caused by Leishmania brasiliensis
- Skin lesions may spread to involve mucosae of nose, pharynx
-
Visceral Leishmaniasis
- Mostly caused by Leishmania donovani
- Occurs in Mediterranean, Asia, South America, Africa
- Fever (typically twice in 24hours), sweats, rigors
- Massive splenomegaly, hepatomegaly
- Pancytopenia secondary to hypersplenism
- Poor appetite*, weight loss
- Grey skin - ‘kala-azar’ means black sickness or black fever
Trypanosomiasis?
- Protozoal disease
- Two main forms
- American Trypanosomiasis (Chagas’ disease)
- African Trypanosomiasis (Sleeping sickness)
- Trypanosoma gambinese - West Africa
- Trypanosoma rhodesiense - East Africa
- Both spread by the tsetse fly
Trypanosoma rhodesiense?
Acute clinical course
- Trypanosoma chancre - tender subcutaneous nodule at site of infection
- Enlargement of posterior cervical lymph nodes
- Later: central nervous system involvement e.g. Meningoencephalitis
Management
- Early disease: IV pentamidine or suramin
- Later disease or central nervous system involvement: IV melarsoprol
Chagas’ disease?
Caused by Trypanosoma cruzi
- 95% asymptomatic in aucte phase
- Chagoma (erythematous nodule at site of infection) and periorbital oedema sometimes seen
- Chronic chagas’ –> affects heart and GI tract
Complications
- Myocarditis –> HF and arrhythmias
- GI –> megaoesophagus and megacolon –> dysphagia and constipation
Management
- Treatment is most effective in the acute phase using azole or nitroderivatives such as benznidazole or nifurtimox
- Chronic disease management involves treating the complications e.g. heart failure
Schistosomiasis?
Parasitic flatworm infection
- Schistosoma mansoni and Schistosoma intercalatum: intestinal schistosomiasis
- Schistosoma Hematobium: urinary schistosomiasis
- Typically presents as a ‘swimmer’s itch’ in patients who have recently returned from Africa.
- Frequency, haematuria and bladder calcification
- Schistosoma Hematobium is a risk factor for squamous cell bladder cancer
- Mx = single dose of oral praziquantel
Rabies?
Features
- Prodrome: headache, fever, agitation
- Hydrophobia: water-provoking muscle spasms
- Hypersalivation
Following animal bite in at risk countries
- If an individual is already immunised then 2 further doses of vaccine should be given
- If not previously immunised then human rabies immunoglobulin (HRIG) should be given along
with a full course of vaccination
Animal bite choice of abx if pen allergic?
Doxy and metronidazole
Cat scratch disease?
Caused by gram -ve rod Bartonella henselae
- fever
- history of a cat scratch
- regional lymphadenopathy
- headache, malaise
Chickenpox general stuff?
- Infectivity = 4 days before rash, until 5 days after the rash first appeared
- Incubation period = 11-21 days
- School exclusion - 5 days from start of skin eruption
- Immunocompromised/newborns with peripartum exposure –> varicella zoster immunoglobulin (VZIG)
- If chickenpox develops then IV aciclovir
Complications of chickenpox?
Secondary bacterial infection of the lesions
- Pneumonia: varicella pneumonia is the most common and serious complication of chickenpox infection in adults. Auscultation of the chest is often unremarkable –> IV acyclovir
- Encephalitis (cerebellar involvement may be seen)
- Disseminated hemorrhagic chickenpox
- Arthritis, nephritis and pancreatitis may very rarely be seen
Foetal varicella syndrome?
Risk of VFS following exposure if 1% if before 20 weeks
Very small chance 20-28 weeks, no chance after 28 weeks
Features
- Skin scarring, eye defects (microphthalmia), limb hypoplasia,
microcephaly and learning disabilities
Management of Exposure
- If there is any doubt about the mother previously having chickenpox maternal blood should be
checked for varicella antibodies - If the pregnant woman is not immune to varicella she should be given varicella zoster immunoglobulin (VZIG) as soon as possible. RCOG and Greenbook guidelines suggest VZIG
is effective up to 10 days post exposure - Consensus guidelines suggest oral aciclovir should be given if pregnant women with chickenpox present within 24 hours of onset of the rash
Measles?
- RNA paramyxovirus
- Spread by droplets
- Infective from prodrome until 5 days after rash starts
- Incubation period = 10-14 days
Complications
- Encephalitis: typically occurs 1-2 weeks after the onset of the illness.
- Subacute sclerosing panencephalitis: very rare, may present 5-10 years following the illness
- Febrile convulsions
- Pneumonia, tracheitis
- Keratoconjunctivitis, corneal ulceration
- Diarrhoea
- Increased incidence of appendicitis
- Myocarditis
Gonorrhoea complications?
Local
- urethral strictures
- epididymitis and salpingitis (hence may lead to infertility)
Disseminated Gonococcal Infection
- Haematogenous spread from mucosal infection
- Triad = tenosynovitis, migratory polyarthritis and dermatitis.
- Later complications = septic arthritis, endocarditis and
perihepatitis (Fitz-Hugh-Curtis syndrome)
Genital warts?
HPV 6 and 11 (16, 18 and 33 predispose to cervical cancer)
Management
- Podophyllum or cryotherapy
- Multiple, non-keratinised warts are generally best treated with topical agents whereas solitary, keratinised warts respond better to cryotherapy
- Imiquimod = topical cream, 2nd line
- Often resistant to treatment, recurrence common - most infections clear within 1-2 years
Genital herpes?
HSV 2 (cold sores are HSV 1)
- Primary attacks often severe, associated with fever; subsequent attacks generally less severe and localised to one site
- Features –> severe gingivostomatitis, cold sores, painful genital ulceration
- Management
- Gingivostomatitis: oral aciclovir, chlorhexidine mouthwash
- Cold sores: topical aciclovir although the evidence base for this is modest
Genital herpes: oral aciclovir. Some patients with frequent exacerbations may benefit from longer term aciclovir
Syphilis?
Spirochaete - Treponema pallidum
Primary
- Chancre - painless ulcer at site of sexual contact
- Often not seen in women
Secondary (4-10 weeks after initial infection)
- Systemic symptoms: fevers, lymphadenopathy
- Rash on trunk, palms and soles
- Buccal ‘snail track’ ulcers (30%)
- Condylomata lata
Latent period
Tertiary
- Gummas
- Aortic aneurysms
- General paralysis of the insane
- Tabes dorsalis (slow degeneration of the sensory neurons. The degenerating nerves are in the dorsal column; proprioception, vibration, and fine touch).
Diagnosis of syphilis?
Serological tests divided into
-
Cardiolipin tests
- Syphilis infection leads to the production of non-specific antibodies that react to cardiolipin
- Examples include VDRL (venereal disease research laboratory) & RPR (rapid plasma reagin)
- Insensitive in late syphilis
- Becomes negative after treatment
- Causes of false positives = pregnancy, SLE, antiphospholipid, TB, leprosy, malaria, HIV
-
Treponemal specific antibody tests
- Example: TPHA (Treponema pallidum hemagglutination test)
- Remains positive after treatment
Lymphogranuloma venereum?
Chlamydia trachomatis
Three stages
- Small painless pustule which later forms an ulcer
- Painful inguinal lymphadenopathy
- Proctocolitis
Cause of BV? Criteria for diagnosis? Pregnancy?
Overgrowth of anaerobes such as Gardnerella vaginalis
Fall in lactic acid producing aerobic lacobacilli resulting in raised vaginal pH
3 of the 4 following for diagnosis
- Thin, white homogenous discharge
- Clue cells on microscopy
- Vaginal pH > 4.5
- Positive whiff test (addition of potassium hydroxide results
in fishy odour)
Managmenet = 5-7 days oral metronidazole
Pregnancy - increased risk of preterm labour, LBW, late miscarriage - oral metronidazole can be used throughout pregnancy
Potential complications of chlamydia?
- Epididymitis
- Pelvic inflammatory disease
- Endometritis
- Increased incidence of ectopic pregnancies
- Infertility
- Reactive arthritis
- Perihepatitis (Fitz-Hugh-Curtis syndrome)
Chlamydia psittaci?
- Parrot disease, parrot fever
- Characterized by malaise, fever, myalgias and pneumonia
- Exposure to an ill bird and a rash (Horder’s spots) are pathognomonic.
- Erythromycin or tetracyclines are the drugs of choice.
Congenital infections?
Most common = CMV
Toxoplasma Gondii?
- Protozoa which infects the body via the GI tract, lung or broken skin
- Its oocysts release trophozoites which migrate widely around the body including to the eye, brain and muscle.
- The usual animal reservoir is the cat, although other animals such as rats carry the disease.
- Most infections asymptomatic - if symptomatic normally self-limiting infection, features resembling infectious mono –> less commonly meningoencephalitis and myocarditis
Gastroenteritis organisms?
Cholera?
Vibro cholerae (gram -ve)
Features
- Profuse ‘rice water’ diarrhoea
- Dehydration
- Hypoglycemia
Management
- Oral rehydration therapy
- Antibiotics: doxycycline, ciprofloxacin
Giardiasis?
Causes by flagellate protozoan Giardia lamblia
Faecal oral route
Features
- Often asymptomatic
- Lethargy, bloating, abdominal pain
- Non-bloody diarrhoea
- Chronic/prolonged diarrhoea, malabsorption and lactose intolerance can occur
- Stool microscopy for trophozoite and cysts are classically negative, therefore duodenal fluid aspirates or ‘string tests’ (fluid absorbed onto swallowed string) are sometimes needed
Salmonella?
Aerobic gram -ve rods (not normally present in gut)
Features
- Initially systemic upset as above
- Relative bradycardia
- Abdominal pain, distension
- Constipation: although Salmonella is a recognised cause of diarrhoea, constipation is more common in typhoid
- Rose spots: present on the trunk in 40% of patients, and are more common in paratyphoid
Possible Complications
- Osteomyelitis (especially in sickle cell disease where Salmonella is one of the most common pathogens)
- GI bleed/perforation
- Meningitis
- Cholecystitis
- Chronic carriage (1%, more likely if adult females)
Shigella?
- Causes bloody diarrhoea, abdo pain
- Severity depends on type: S sonnei (e.g. from UK) may be mild, S flexneri or S dysenteriae from abroad may cause severe disease
- Treat with ciprofloxacin
African tick typhus?
Caused by Rickettsiae
- Black sopits on thigh
- Hx of tick bites
- Low grade fever
- Faint macular rash
Rocky mountain spotted fever?
Spread by ticks, common in the USA
- Fever
- Rash on hands, feet which later –> desequamte (peel)
- Tachycardia with no hypotension (unlike Staphylococcal Toxic Shock Syndrome)
Treat with doxycycline
Mediterranean spotted fever?
Caused by the Rickettsia conorii and transmitted by the dog tick Rhipicephalus sanguineus
- Incubation period: 7 days.
- Abrupt onset - chills, high fevers, myalgia and joints pain, severe headache, photophobia and diarrhea.
- The location of the bite forms a black spots or ulcerous crust (tache noire).
- Around the fourth day of the illness exanthem appears, first macular and then maculopapular and sometimes petechial
Treat with Doxycycline
Dengue fever?
Type of viral haemorrhagic fever (yellow fever, Lassa fever, Ebola)
Low platelet count and raised transaminase level is typical
- Transmitted by the Aedes aegyti mosquito
- Incubation period of 7 days
- Africa, Central and South America, the Caribbean, the Eastern Mediterranean, South and Southeast Asia, and Oceania.
- Form of DIC called dengue haemorrhagic fever (DHF) may develop –> Dengue shock syndrome (DSS)
Features
- Causes headache (often retro-orbital)
- Myalgia
- Pleuritic pain
- Facial flushing (dengue)
- Maculopapular rash
- Pyrexia
Treatment is symptomatic - fluid resus, transfusions etc.
Infectious mononucleosis?
Caused by EBV
- Sore throat
- Lymphadenopathy
- Pyrexia
- Malaise, anorexia, headache
- Palatal petechiae
- Splenomegaly - occurs in around 50% of patients and may rarely predispose to splenic rupture
- Hepatitis
- Presence of 50% lymphocytes with at least 10% atypical lymphocytes
- Hemolytic anaemia
Management - rest, fluids, simple anaglesia. No contact sport for 8 weeks.
Malignancies associated with EBV infection?
- Burkitt’s lymphoma
- Hodgkin’s lymphoma
- Nasopharyngeal carcinoma
- HIV-associated central nervous system lymphomas
Hairy leukoplakia also associated with it (non-malignant)
Hepatitis E?
- RNA virus
- Spread by the faecal-oral route, incubation period = 3-8 weeks
- Common in Central and South-East Asia, North and West Africa, and in Mexico
- Causes a similar disease to hepatitis A, but carries a significant mortality (about 20%) during pregnancy
- Does not cause chronic disease
Parvovirus B19?
Erythema infectiosum (also known as fifth disease or ‘slapped-cheek syndrome’)
- Systemic symptoms: lethargy, fever, headache
- ‘slapped-cheek’ rash spreading to proximal arms and extensor surfaces
Other presentations
- Asymptomatic
- Pancytopenia in immunosuppressed patients
- Aplastic crises e.g. in sickle-cell disease (parvovirus B19 suppresses erythropoiesis for about a week so aplastic anemia is rare unless there is a chronic hemolytic anemia)
Orf?
- Condition found in sheep and goats although it can be transmitted to humans.
- Caused by the parapox virus.
In humans
- Generally affects the hands and arms
- Initially small, raised, red-blue papules
- Later may increase in size to 2-3 cm and become flat-topped and hemorrhagic
In animals
- Scabby leisons around mouth and nose
Nematodes?
-
Ancylostoma braziliense
- Most common cause of cutaneous larva migrans
- Common in Central and Southern America
-
Strongyloides stercoralis
- Acquired percutaneously (e.g. Walking barefoot)
- Causes pruritus and larva currens - this has a similar appearance to cutaneous larva migrans but moves through the skin at a far greater rate
- Abdo pain, diarrhoea, pneumonitis
- May cause gram negative septicemia due to carrying of bacteria into bloodstream
- Eosinophilia sometimes seen
- Management: thiabendazole, albendazole. Ivermectin also used, particularly in chronic infections
-
Toxocara canis
- Commonly acquired by ingesting eggs from soil contaminated by dog faeces
- Commonest cause of visceral larva migrans
- Other features: eye granulomas, liver/lung involvement
Tape worms?
Cysticercosis
- Caused by Taenia solium (from pork) and Taenia saginata (from beef)
- Management: niclosamide
Hyatid disease
- Caused by the dog tapeworm Echinococcus
granulosus - Life-cycle involves dogs ingesting hydatid cysts from sheep liver
- Often seen in farmers
- May cause liver cysts
- Management: albendazole
