Revision Sm Gr Flashcards
Revision DM Yaws
T pallidum subsp pertenue. Most cases in children. Major foci W&C Africa and Pacific. Large gaps in understanding of distribution = barrier to eradication. Single dose azithromycin for Rx. Risk of resistance. WHO strategy (Mapping of foci, Treatment of whole community, Likely need several rounds, Then mop up with treatment cases and contacts, Once no more cases switch to serological surveillance). Comment: Use the epidemiological cues
Revision DM HIV-TB
Priority group for rapid ART initiation (high risk death). After ART: high risk death, unmasking OI, IRIS, failure to fully immune reconstitute, AIDS-related and non-AIDS related comorbidities. At diagnosis, needs screen for 1 TB disease (all patients), 2 Cryptococcal infection (CD4<100, consider <200) If these are negative evaluate for other infections according to clinical presentation and local epidemiology. Check if on ART (and failing)/received prior ART (treatment interruption). Screening TB disease in advanced HIV: A) Screening tools: 4-symptom screen (Current cough, weight loss, fever, night sweats), CRP, CXR, molecular RDT. Choice of tests depends on setting (in patients, outpatients) feasibility and resource. B) This patient has screened positive on 4-symptom screen: Cough and fever. Molecular WHO recommend RDTs recommended as first test for pulmonary TB diagnosis: high sensitivity, specificity, additional drug sensitivity info, urgency of timely diagnosis in this population. CXR may help support diagnosis. Urine LAM may assist diagnosis for the following: (CD4<20 in inpatients, CD4<100 in outpatients, Any CD4 count if symptoms or seriously ill). Comment: CXR reasonable to do, is it the first thing you would do? Possibly? Fever and a cough, but most likely diagnosis is TB (HIV in South Africa). LAM not as useful if you’re not particularly sick, and is usually a screening in an unwell patient. CRP is reasonable but not first test
Revision DM Polio
Caused by 3 strains of poliovirus. Only humans. Transmission is faeco-oral. Most infected individuals are asymptomatic but about 25% develop a febrile illness usually with GI symptoms. Neurological and paralytic complications are rare (0.5% of the time-typically asymmetrical paralysis of the affected limb (usually the legs) but acute flaccid paralysis (AFP) surveillance remains key to polio efforts. Transmission of wild-type polio is now restricted to Pakistan and Afghanistan. Highly effective vaccines- live oral vaccine (OPV-Sabin) prevents disease and generates sterilising immunity but has risk of vaccine-associated polio disease. OPV used in disease-endemic outbreak affected areas and recently polio-free countries of the world. IPV (Salk) prevents disease but can’t block transmission. IPV used in the rest of the world, where the risk of vaccination-associated paralytic polio is considered greater than the risk of naturally occurring infection. IPV introduced for Polio 2 as wild-type polio 2 no longer circulating. No animal reservoir – should be able to be eradicated. Comment: Pakistan, Afghanistan is wild type Polio (vaccine-derived elsewhere)
Revision DM Viral hepatitis
Hepatitis A Transmission: faecal oral Incubation: 15-50d. Acute <6yo <1/3 have symptoms, >70% older children and adults have symptoms. Chronic infection – none. Hepatitis B Transmission: at birth, sexual contact, sharing needs. Incubation 60-150d. Acute infection - symptoms <5yo none, >5yo 30-50% symptomatic. Immunocompromised adults, generally none. Chronic infection: 90% birth, 25-50% 1-5y, 5% adults. Hepatitis C Transmission: Sharing needles, anal intercourse. Incubation 14-182d. Acute non-specific symptoms in 10-20%, jaundice in up to 20-30%. Chronic >50%. Hepatitis E Transmission: Faecal oral, contaminated water. Incubation 14-70d. Acute <30% symptomatic. Significant mortality risk in pregnant women. Chronic HEV 3/4 unclear %. Comment: If this question said Egypt – consider hepatitis C. West Africa has lots of hepatitis B with accelerated HCC
Revision DM Buruli ulcer
Mycobacterium ulcerans. Transmission seems to be linked to water/soil. Can present as an ulcer or a non-ulcer form such as nodule or plaque. Lesions are normally painless and the patient is systematically well. PCR is the test of choice (Swabs from ulcer lesions undermined edge, FNA from non-ulcerative forms). Treatment: Rifampicin and Clarithromycin for 8 weeks, Wound care, May need debridement or skin graft. Comment: Scar, expansive ulcers with contractures. Alternative options Skin snip is for Onchocerciasis. Slit skin smear is for leprosy.
Revision DM Zika
Primary vector Aedes aegypti – day biting, breeds in small pools of water (eg containers). Surveillance: Syndromic and case surveillance, Laboratory surveillance, Zika – microcephaly surveillance. Active case finding when outbreaks identified Education: public and HCW (Symptoms and Vector control). Vector control – source reduction (Elimination of containers/fitting lids, Insecticides against aquatic stages, Space spraying (outbreaks), Pupal surveys to target source reduction measures. No vaccination yet Comment: Bed nets not effective as day biting, residual spraying of insecticide not so useful (Aedes aegypti are endophilic- like to bite indoors). Insect repellent useful (throughout the day, not just in the evening).
Revision DM Brucella
Brucella sp are small aerobic intracellular GNCB. There are four strains medically important to human B melitensis, B abortus, B suis and B canis. Incubation period can be long days to months. Brucellosis is the commonest bacterial zoonosis globally – transmission from animals to humans is usually via uncooked meat, unpasteurised milk/dairy, aerosolization. Clinically non-specific symptoms, with a usually normal examination. Undulating fever, hepatosplenomegaly, arthralgia, elevated liver enzymes, mild moderate thrombocytopaenia may be present. Culture (gold standard) everything you can, ELISA, Rose Bengal and PCR testing is also used diagnostically. Treatment with doxycycline (45d) and gentamicin (7-10d) or streptomycin (15d) is recommended by the WHO. Vaccine is available for animals (B melitensis and B abortus) but not humans. Prevention: BSC3 lab handling – don’t sniff the plates. Appropriate PPE should be used around potentially infected animals and their products. Comment: The alternative diagnosis for 34M Somalia with LN, epididymoorchitis would be TB. Also think of Mongolia and/or slaughterhouse worker for Brucella. Anthrax is also important for slaughterhouse worker.
Revision DM Malaria
Treatment of malaria relies on classifying if the patient has severe/complicated OR uncomplicated malaria. Signs of complicated malaria: CNS coma/convulsions (cerebral malaria), Lungs ARDS, Kidney AKI, Shock, Hypoglycaemia, Severe anaemia, Respiratory distress or acidosis, Hyperparasitaemia. ACT are first line treatment of uncomplicated malaria caused by all species. For complicated malaria SEQUAMAT and AQUAMAT both showed artesunate to be superior to quinine. Severe/complicated malaria is associated with a high rate of bacteraemia in children – normally due to non-typhoidal Salmonella and therefore treatment with a broad spectrum ab is normally recommended. Comment: Approach to question: Will always favour ACT over quinine. Have they got severe? Probably then Artemether > artemether/lumefantrine. Then decide if giving CRO or not – he is very sick and may have more than just malaria. If fever and positive RDT then would give Artemether/lumefantrine (or whatever ACT) and would not need to give antibiotics. Also, do not generally need to give abx to adults unless very sick. When children are sick, it is generally due to gut leakage/translocation.
Revision DM Rheumatic fever (RHF) and heart disease
RHF an immunological reaction to GAS (Type 2 hypersensitivity) – classically after pharyngitis. RHF: Duckett-Jones criteria: fever, arthritis, carditis, nodules, chorea. Repeated RHF->RHD. Primary prophylaxis: early treatment streptococcal pharyngitis. Secondary prophylaxis: benzathine penicillin. GAS also associated with glomerulonephritis (Classically after a skin infection, Type 3 hypersensitivity reaction with immune complexes). Comment: Endomyocardial fibrosis is rare, may be associated with chronic eosinophilia and found not in frequently in Mozambique. Undiagnosed congenital heart disease possible, but in a child from Samoa with features of heart failure, it is RHD until proven otherwise.
Revision DM Amoebic dysentery
Parasitology: non-flagellated protozoan parasite. Transmission via faecal-oral ingestion of mature cysts. Excystation in small bowel and trophozoite esp migrate to large bowel and invade (>ulcers and mucosal loss). Clinically: Subacute onset, over 1-3 weeks, Asymptomatic -> mild diarrhoea -> dysentery (-> fulminant colitis), Fever 50%, Fewer WBCs in stool compared to bacillary dysentery – the ulcers don’t have marked inflammation around them. Geography throughout tropics. Diagnosis: (Hot stool for microscopy for trophozoites – poo to microscope within 20 minutes, or Concentrated stool: microscopy for cysts plus PCR). Misdiagnosis – mistaking amoebic dysentery for inflammatory bowel disease – treating with steroids may precipitate fulminant colitis. Treatment: A Symptomatic intestinal amoebiasis (Metronidazole 5-10d, If severe/fulminant may need Gram negative cover +/- surgery) B Asymptomatic and cyst clearance post A need intraluminal agent (Paromomycin (25-30mg/kg per day orally in three divided doses for 7 days). Iodoquinol may also be considered. Comment: Salmonella enteritis is less common to cause blood in stool. Shigella enteritis – bacillary enteritis is much more abrupt and unpleasant illness – usually faster onset of illness. Clostridium difficile colitis can cause similar presentation, but usually previous antibiotics.
Revision DM Leprosy
M leprae. Likely respiratory spread with very long incubation. Clinical presentation depends on immune response. WHO simplified classification: PB 5 or less, MB 6 or more. WHO now recommends 3-drug regimens for all leprosy: Rifampicin 600mg once a month, Clofazimine 300mg once a month and 50mg daily, Dapsone 100mg daily. Duration: PB 6 months, MB 12 months. Many patients experience reactions despite effective treatment (or may present in reaction). Type 1 reaction (Usually painful neuritis with loss of function. Involve existing lesions (thickened nerves become painful). Treated with steroids (as soon as possible)). Type 2 reactions – much more common in Lepromatous Leprosy (Systemic illness with Erythema Nodosum Leprosum, Red shiny painful skin lesions which last a long time, Poorly responsive to steroids, Thalidomide probably the best).
Revision DM IRIS
Immune reconstitution inflammatory syndrome. Due to inflammation caused by IRIS following ART. Usually within weeks, up to a few months. ‘Paradoxical’ if OI being treated. ‘Unmasking’ if subclinical when started ART. Usually not fatal (except CNS). Treatment usually steroids. Importance of screening for OIs. Patients on antiTBRx given ART -> Paradoxical. Patients not on antiTBRx given ART -> ART-associated TB = Unmasking IRIS (released the pressure on the immune system) – can get with other pathogens. Comment: HIV on SXT = likely very immunosuppressed. Shortly after starting ART. Stopping ART does not solve the problem, give steroids usually, cannot delay ART for too long as they die of other HIV OI. Timing is important – 3 weeks is classic (2-8w is unmasking time). Paradoxical IRIS can occur at any stage in treatment, in people without HIV can happen 4-5 months into treatment.
Revision DM Urethral discharge
WHO recommends the use of syndromic management of most STIs. Entails treatment of the common causes of a given set of symptoms and signs. Commonest causes of urethral discharge are NT (Rx CRO + azithromycin, CT: Rx with doxycycline or azithromycin). Advantages of syndromic management (Sensitive for symptomatic STIs. No need for lab tests). Disadvantages (Not specific, Results in over-treatment). Ideally offer HIV and syphilis testing also
Revision DM Yellow fever
Introduction to human in the jungle from mosquitoes that have bitten non-human primates and can then spill over to urban or village. VHF caused by an RNA flavivirus. Incubation 3-6d. Major asymptomatic or mild symptoms. Flu like illness starting about 1 week. Approx 1:7 patients with symptom develop severe infection; high fever, jaundice, bleeding, multi-organ failure. No effective treatment, supportive only, avoid NSAIDS. Infectious for approx. 5d post symptom onset (bed net etc). YF vaccination is safe, effective and provides lifelong immunity – aim for 100% coverage in endemic regions, esp in areas with confirmed epizootic transmission. Comment: Chagas is transmitted by triatomine bugs, Remdesivir is not effective (for almost any virus), Sylvatic cycle is non-human primate jungle cycle.
Revision DM Enteric fever
S typhi and paratyphi. Faeco-oral transmission. Endemic in south Asia but also across much of the tropics. Best diagnostic test is bone marrow culture although in clinical practice blood culture is the standard. The Widal test though widely used is mostly no good (unless you are in a high prevalence setting and know the background). Is NOT more common in HIV infected people. Increasing resistance to a range of Abx - CRO is now 1st line in S Asia but increasing resistance. Azithromycin an alternative option. XDR strains have emerged independently in Pakistan and Nepal. Fever may take a long time (often a week) to go away even with correct Rx. Complications like bowel perforation and haemorrhage occur in week 3. New conjugate vaccine looks highly effective. Comment: Best diagnostic yield is from BM, but it is probable that 3x BC gives the same yield. Pakistan – think about polio and Nepal. Think about drug resistance
Revision DM PMTCT for HBV
Risk related to viral load in mother. Once chronic infection is established there is no cure possible. Vaccination needs to be delivered at birth to be effective. Coverage in much of sub-Saharan Africa is <10%. IG at delivery further reduces risk but is rarely available in LMIC. Tenofovir to mother from week 30 reduces the risk. No role for single dose treatment. Comment: TDF from week 30 to week 4 post-partum (probably does reduce transmission but not as critical as vax and immunoglobulin). Slides shown of study of TDF in addition to standard of care – HBVvax and HBIG on first day of life – some benefit, but HBIG seems to be the best.
Revision DM Cervical Cancer
High prevalence of CxCa across SSA. Strongly associated with HPV 16 18. Increased risk for people living with HIV = synergy for CaCx esp in Africa. Screening for HPV is the most sensitive test. HPV vaccination is highly effective in prevention of cervical cancer and probably in preventing other HPV-associated cancers. Evidence increasingly supports need for only 1-2 doses of HPV vaccination. Comment: Smoking is a risk factor, but not the most important risk. Individuals living with HIV are at an increased risk of CaCx. Genital Schistosomiasis may mimic CaCx, but is less common than HPV-associated CaCx.
Revision DM Scabies
Sarcoptes scabiei. Ectoparasite. Spreads person to person by prolonged skin to skin. Treatment: Ivermectin oral – 2 doses, 7 days apart (Contraindicated if pregnant, BG <15kg or less than 5yo. Topical therapy: Benzylbenzoate or Permethrin (probably the best)
Revision DM Rapid ART
When is rapid ART NOT recommended: Crypto meningitis (Increased mortality with immediate ART. Defer until 4-6W after CM treatment start) and TB meningitis (Delay ART for at least 4W but start within 8W of anti-TB treatment. Consider adjuvant steroids). Important considerations in treatment of HIV-TB coinfection (1 Interactions with ART, if on or due to start ART, 2 When to start ART if not on ART, 3 TB-IRIS). ART should be started in all TB patients living with HIV regardless of their CD4 count. TB treatment should be initiated first, followed by ART as soon as possible within the first 8 weeks of treatment (Strong recommendation). HIV-positive patients with profound immunosuppression (CD4<50) should receive ART within the first 2 weeks of initiating. Comment: exclude TB is right, but ‘check no clinical evidence of meningitis’ is better. CD4 is useful to assess risk of OIs, but not essential prior to initiation of ART. All patients living with HIV eligible for ART. Need to start investigations for active TB (weight loss = screen positive), however, providing no evidence of meningitis you don’t need to wait for results before starting ART. All HIV patient should be screened for STI but this should not delay starting ART. Adherence support is important
