NTD Flashcards
Schistosomiasis - definition/organisms
Water-borne parasitic infection with an intermediate host of freshwater snails. Two primary syndromes including intestinal (S.mansoni, S. japonicum) and urogenital (S.haematobium)
Schistosomiasis - geographical distribution
Mansoni - Sub-Saharan Africa and Brazil
Japonicum - China, Philippines, Indonesia
Haematobium - Sub Saharan Africa
Intestinal schistosomiasis clinical features
Diarrhoea, abdominal pain, blood in stool
Chronic inflammation can lead to intestinal strictures and obstruction, as well as liver fibrosis and portal hypertension
Urogenital schistosomiasis clinical features
Haematuria, dysuria. Chronic inflammation leading to contractures, hydronephrosis and squamous cell carcinoma of the bladder
Male/female genital schistosomiasis can cause STI symptoms like vaginal/bloody discharge and itch, pain during sex, infertility, increased risk of HIV
Acute (Katayama fever)
4-6 weeks later fever, urticaria, cough, abdominal pain
Schistosomiasis non-specific clinical features
Anaemia, growth faltering, reduced educational performance, cecariae dermatitis
Ectopic presentations of schistosomiasis
Transverse myelitis, pulmonary HTN and cerebral schistosomiasis
Schistosomiasis diagnostics - parasitological methods
- Stool microscopy - Kato-Katz (thick faecal smear)
- Urine microscopy - egg count, urine filtration and centrifugation
Intestinal schistosomiasis - diagnostics
- Stool microscopy
- Faecal occult blood/calprotectin
- Eosinophils + Hb
- Colonoscopy
- US liver
Urogenital schistosomiasis - diagnostics
- Urine microscopy
- Urine dip (haematuria)
- Urine antigen detection CAA (cannot speciate)
- Ultrasound and cystocopy
- Eosinophilia
Schistosomiasis - returning traveller approach to diagnostics
- Asymptomatic â wait for 3 months after last freshwater contact.
- Serology for schisto antibodies
- Blood count (Hb, eosinophilia)
- 3 x MSU for RBCs/ova
- 3 x stool for ova - Febrile presentation
- Exclude other life threatening illnesses
- Will need repeat PZQ if diagnosis confirmed
- Unclear whether steroids might be worth giving - Symptoms e.g. haematuria/change in ejaculate
Same as 1. and refer to Urology/Gastro/Gynae depending on symptom
Schistosomiasis - returning from an endemic area - approach to diagnostics
- Asymptomatic
- Blood count (eosinophilia)
- 3 x MSU RBCs/ova
- 3 x stool for ova
- Urine antigen detection CAA (most sensitive and can be used for all types, CCA for S mansoni) - Symptoms or signs (e.g. haematuria, splenomegaly)
Same as 1 and include onward referral to Urology/Gastro/Gynae
Schistosomiasis treatment
Praziquantel
Needs repeat as not effective against non-adult forms
Praziquantel in schistosomiasis - pros and cons
Pros:
- Safe
- Effective against all species
Cons:
- Only effective against adults
- Global shortage
- Requires second dose a month later
- Taste is horrible
Prevention measures in schistosomiasis
- MDA annually in endemic regions
- Improved sanitation (open defecation and urination)
- Snail control - mulluscicides, habitat modification
- Safe water provisions
Onchocerciasis - organism
Onchocerca volvulus parasite
Onchocerciasis - transmission
Transmitted by blackflies (Simulium damnosum and Simulium ochraceum). Females bite outdoors in the daytime
Onchocerciasis - life cycle
- Blackflybites host and delivers 3rd stage larvae into the skin
- Larvae mature into adult worms in the subcutaneous tissue (itching)
- Adult worms produce microfilariae which migrate through the skin and eyes. They die, leading to inflammation and pathology
- When a blackfly bites a human it ingests the microfilariae which move into the midgut then to flight muscles before moving on to the mouthparts
Onchocerciasis - clinical features
- Skin - itching and firm/painless subcutaneous nodules in the acute stage followed by skin atrophy and patchy depigmentation (leopard skin) chronically
- Eye symptoms including keratitis, anterior uveitis, secondary cataracts, optic atrophy and chorioretinitis.
- Neurological - epilepsy, nodding phenomenen
Ochocerciasis - diagnostics
- Skin snips with microscopy to see the microfilariae
- Ov16 ELISA test
Onchocerciasis - treatment
- Ivermectin - does not kill adult worms so often needs prolonged/recurrent treatment
- Doxycycline - kills the Wolbachia bacteria which is needed for worm fertility. Give a 4 week course for definitive treatment.
Prevention strategies in onchocerciasis (5)
- Community directed treatment with ivermectin (MDA)
- Vector control - insecticide and environmental management
- Health education
- Surveillance and mapping
- Cross-border collaboration
Challenges in eliminating onchocerciasis (7)
- Cross border re-invasion
- Treatment limitations (ivermectin does not kill adult worms)
- Co-infection with Loa Loa endemicity as ivermectin can be life-threatening
- Sustaining public interest and funding in the longterm
- Conflict zones
- Competing public health concerns
- Capacity building of expertise - public health, entomologists, laboratories
Baylisascaris procynosis - definition
A racoon round worm infection from old poo (not fresh).
Found in Europe, N.America, Japan
Baylisascaris - clinical features
Human infections often asymptomatic but can cause visceral larva migrans, neural larva migrans and ocular larva migrans
Baylisascaris - treatment
Zap the eye with laser
Albendazole
Steroids in neurological diseases
Diffuse unilateral subacute neuroretinitis - definition and causes (5)
DUSN is caused by a live, motile nematode infecting the retina
It primarily affects one eye and leads to inflammation, vision loss, and retinal damage if untreated
- Gnathatoma - Thailand - eating raw fish/frog (drill head)
- Angiostrongylus - America, Vietnam, Thailand, Hawaii
- Toxocara canis, ancylostoma caninum (dog poo)
- Strongyloides
- Baylisascaris
Ciguatera poisoning - symptoms
Diarrhoea and vomiting within hours of ingestion
Neurological symptoms 3-72 hours after ingestion (paraesthesia, metallic taste, hot/cold allodynia, reversible cerebellar dysfunction)
Cardiovascular: Bradycardia, heart block, hypotension
Ciguatera poisoning - definition
Non-bacterial fish poisoning which can occur worldwide - especially Asia and Caribbean
Ciguatera poisoning - differentials
GBS, MS, organophosphate poisoning, botulism, scombroid, shellfish and pufferfish poisoning
Scombroid - symptoms
ALLERGY - Rash, palpitations, tachycardia
Shellfish poisoning - symptoms
GI upset, rapid onset pararesthesia and paralysis
Pufferfish poisoning - symptoms
Weakness (Na channel blockage)
Botulism - symptoms
GI upset, CN dysfunction, descending paralysis
Sea urchin injury - definition and treatment
Painful, visible puncture wounds
Causes granulomatous inflammation
1. Hot water soak
2. Remove visible spines where possible
3. Cover with antibiotics (staph, strep, mycobacterium marinarum, aeromonas hydrophilia) and topical steroids
Phytophotodermatosis - definition
Contact dermatitis on the skin when certain compounds are exposed to sunlight. This reaction results in skin inflammation and can cause blistering, redness, and hyperpigmentation.
Cutaneous leishmaniasis (diagnostics)
Slit skin smear (Giemsa stain) and biopsy
Cutaneous leishmaniasis (types)
American (more aggressive) - L.brasiliensis/viannia, L.Mexicana
Non-American - L.tropica, L.major, L.aethiopica
Leishmaniasis - treatment
Local
1. Intra-lesional antimony
2. Heating/freezing
Systemic:
1. PO/IV miltefosine
2. IV liposomal amphotericin B
Migratory rashes differentials
Gnathastoma spinigerum
Sparganosis
Cutaenous larva migrans
Strongyloides sterocoralis
Loa loa
Eczema
Phytophotodermatosis
Trichinosis (raw pig)
Gnathostomiasis - organism, geographical distribution and exposure risk
Gnathastoma spinigerum
SE Asia, increasingly in Mexico
Eating undercooked/raw freshwater fish which is the intermediate host
Gnathostomiasis - symptoms
Acute
Fever, urticaria, GI symptoms
Chronic
Migratory swelling, visceral (lung, GI, meningitis)
Gnathostomiasis - Treatment
Albendazole 3 weeks
Gnathostomiasis - Diagnosis
Clinical
Eosinophilia
Serology
Leptospirosis
GBS infectious causes
Campylobacter, shigella, influenza, mycoplasma, HIV, covid
Visceral leishmaniasis case definition
Fever (>2 weeks) + splenomegaly + positive RDT
Visceral leishmaniasis - geographical distribution
South Asia, East Africa, Latin America
Visceral leishmaniasis - transmission
Vector: Sandfly - night biting females, can feel the bite.
Reservoirs: Humans, dogs
Visceral leishmaniasis - clinical features and labs
Fever, splenomegaly, hepatomegaly, anaemia
Weight loss, anorexia, cough, diarrhoea
Labs:
Hypergammaglobulinaemia, anaemia, leucopenia, thrombocytopenia, proteinuria and haematuria
What is PKDL?
Post Kala Dermal Leishmaniasis
Non-fatal skin considition post visceral leishmaniasis
Diagnostics in visceral leishmaniasis
- Gold standard: Microscopy of LD bodies in Giemsa-stained smears from spleen, lymphoid tissue and bone marrow
- Slit skin smear in PKLD
- HIV screen
- PCR (more often used in research setting, can speciate)
- Serology (rk39 antigen test)
What is rk39 antigen test used for?
Serology for visceral leishmaniasis in Asia
How do you diagnose PKDL?
Slit skin smear
Treatment in visceral leishmaniasis
- Liposomal amphotericin B
- Miltefosine
- Paromomycin
HIV: Combination L-AMB + miltefosine
Cutaneous leishmaniasis - epidemiology
Old world (Non-American) - Phlebotomus sandfly
New world (Americas) - Lutzomyia sandfly (also think viannia)
Cutaenous leishmaniasis clinical features
Localised:
Wide range of skin lesions including ulcers, nodules, keratotic plaques on exposed areas
Systemic (more common in HIV/immunsuppression)
Mucosal involvement (nose, throat and mouth)
Disseminated, nodular lymphangitis
Cutaneous leishmaniasis - diagnostics
- Microscopy and histology - visualisation of amastigotes in smears or tissue sections
- Culture
- PCR
NO ROLE FOR SEROLOGY
Treatment cutaenous leishmaniasis
Key concept: localised vs diffuse infection, is there a risk of mucosal spread (i.e. Americas, viannia, immunosuppressed)
- Conservative
- Local
- Intralesional antimonials
-Cryotherapy
-Surgery - Systemic
- Pentavalent antimonials e.g. meglumine
- Miltefosine (PO) 28 days, teratogenic + nausea
- Amphotericin B
Meglumine
Pentavalent antimonial used in the treatment of leishmaniasis
Miltefosine
Used in treatment of leishmaniasis, teratogenic and associated with nausea
Viperidae snake features
Vipers, adders, rattlesnakes
Short thick body
Slow moving, ambush
AKI
severe local swelling and bruising
Elapidae snake features
Cobra, kraits, coral snakes, all Australian venemous snakes
Long thin body
Fast moving
Descending flaccid paralysis. Ptosis â> bulbar/resp paralysis â> necrosis
Classic features of a scorpion bite
Autonomic storm - massive release of acetylcholine and catecholamines
Cardiorespiratory effects - HTN, shock, pulm odoema
Neurotoxic effects - fasiculation, muscle spasm
How to manage a snake bite?
Remove from danger
Reassure
Remove tight clothing from the leg
Immbolisation
Pressure pad
Trachoma - organism and pathophysiology
Chlamydia trachomatis
Recurrent infections leads to inflammation, leading to scarring of the eyelid and entropion. This continued trauma leads to corneal scarring.
Trachoma - transmission
The 3 Fâs
Fingers, flies and formites (surfaces)
Trachoma - clinical features
Stage 1 - Trachomatous inflammation (follicular) TF
Stage 2 - Trachomatous inflammation intense (TI)
Stage 3 - Trachomatous scarring (TS)
Stage 4 - Trachomatous trichiasis (TT)
Stage 5 - Corneal opacity (CO)
Trachoma Stage 1 - Trachomatous inflammation (follicular) TF
5 or more follicles on the conjunctiva
Treat with antibiotics - single dose of azithromycin
Trachoma Stage 2 - Trachomatous inflammation intense (TI)
Tarsal conjunctiva appears red, rough and thickened
Treat with antibiotics - single dose azithromycin
Trachoma Stage 3 - Trachomatous scarring (TS)
C trachomatis not often found, just evidence of the scarring
Therefore no treatment suggested
Trachoma Stage 4 - Trachomatous trichiasis (TT)
C trachomatis not often found
Evidence of at least one eyelash rubbing on the eye
Needs surgical management - posterior lamellar tarsal rotation surgery
Trachoma Stage 5 - Corneal opacity (CO)
Pupil margins blurred due to opacity
Past the point of treatment as the damage has already been done
Which stages of trachoma do not warrant treatment?
Stage 3 - trachomatous scarring
Stage 5 - corneal opacity
Which stages of trachoma warrant antibiotics?
Stage 1 - trachomatous inflammation (follicular) TT
Stage 2 - trachomatous inflammation (intense) TI
What is the treatment strategy for trachoma?
S - surgery
A - antibiotics, including MDA
F - facial cleanliness
E - environmental (better access to water and sanitation)
What makes an NTD suitable for elimination? (4)
- No animal reservoir
- Effective intervention
- Amenable to surveillance
- Public health importance
What is the difference between elimination and eradication?
Elimination is reducing the incidence of a disease to zero in a defined geographical area. Continued interventions are required to prevent re-introduction
Eradication is permanently reducing the incidence of a disease to zero worldwide
Yaws - organism
Treponema pertenue
Gram negative spirochaete
Clinical stages of Yaws
Primary: Initial skin lesion at infection site
Secondary: Spread to other parts of the body, characterised by more extensive lesions
Tertiary: Severe tissue and bone destruction to the face and lower limbs
Latent: Can become formant and asymptomatic
Yaws - treatment
Azithromycin
Noma - definition
Rapidly acting orofacial gangrene most commonly affecting children aged 2-5 years
Noma - treatment
Antibiotics
Antiseptic mouthwash (e.g. chlorhexidine)
Nutritional support
Surgical debridement
Buruli ulcer - organism
Mycobacterium ulcerans
Buruli ulcer - geographical distribution
Africa + Australia
Buruli ulcer - diagnosis
PCR is the gold standard
Takes months to culture
Histopathology can be helpful
Buruli ulcer - clinical features
Papules, nodules, plaques and odoema
Buruli ulcer - treatment
Rifampicin + clarithromycin for 8 weeks
Guinea worm - organism
Dracunculus medinensis
Guinea worm - life cycle
Drink unfiltered water with L3 larvae
Spend 14 months in the intestine
Females migrate to the skin and release larvae into the water which take 14 days to mature
Risk factors for crusted scabies
Older age
Immunosuppression
HIV/HTLV1
Malnutrition
