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Tropical Medicine; a whistle stop tour. R Johnson MBBS MRCS DTM&H. Malaria. 2 million fatalities per year Almost all P. falciparum “tropical” Stable vs unstable transmission; immunity Simple vs complicated. Life Cycle. Infected female anopheline mosquito Sporozoites enter hepatocytes
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Tropical Medicine; a whistle stop tour R Johnson MBBS MRCS DTM&H
Malaria • 2 million fatalities per year • Almost all P. falciparum • “tropical” • Stable vs unstable transmission; immunity • Simple vs complicated
Life Cycle • Infected female anopheline mosquito • Sporozoites enter hepatocytes • Hepatic shizont once mature ruptures and release merozoites into blood • Erythrocytic trophozoites mature into shizonts and then precipitate sequestration • Rupture to produce merozoites or gametocytes
Clinical Features • The great pretender • Fever, cough, muscle aches, diarrhoea, abdo pain, headache, seizures, haematuria • Hypoglycaemia • Anaemia; haemolysis and marrow suppression • Splenomegaly • Jaundice • Cyclical nature of fever?
Diagnosis • Thick and thin films • Serology • Buffy coats • PCR
Treatment 1 • Antipyretic • Rehydration • Blood transfusion • Anti-convulsants • Correcting hypoglycaemia • Reducing acidaemia • Antibiotics
Treatment 2 • Chloroquine. Non-toxic, oral or IV • Quinine. Toxic. Effective, oral or IV • Mefloquine. Single dose due to long half life. Toxic. Negative inotrope. • Fansidar. Resistance! • Artemesinins. Effective, combination therapy
Prophylaxis • Don’t get bitten • Dependant on area • Dependant on what you are doing • Dependant on time spent in malarious area
Typhoid • Salmonella typhi and paratyphi A, B, C • Water bourne, oro-faecal • Infect small bowel lymphatics, • Bacteraemia, bone marrow, spleen, liver and gallbladder • Secondary bacteraemia and invasion of bowel
Timeline • Incubation 14 days (7-21) • Week 1, non-specific illness with fever (intermittent), cough, diarrhoea or constipation • Week 2, rose spots, constant fever, abdo pain. Very toxic • Week 3, dehydation, metabolic mayhem. GI haemorrhage, multiple small bowel perforations • Week 4, if reached, fever lysis and recovery. • Other presentations; meningitis, pneumonia, renal failure • Long-term sequelae; osteomyelitis, typhoid abscess, chronic carriage
Diagnosis • Culture; blood, marrow, csf • Serodiagnosis; Widal test
Treatment • Chloramphenicol • Amoxycillin or septrin as alternatives • MDR • Cefotaxime
Arboviruses • Ecological description • Three clinical syndromes • FAR • VHF • CNS • Supportive care
Travellers diarrhoea • Probably majority viral • Bacterial • Un-exposed normal flora • Simple; 2 doses of cipro, 3 days of trimethoprim • Blood = dystentery; • Ameobic, shigella, campylobacter, E. coli 157