Tropical Gastroenteritis Flashcards by Aalap Asurlekar

Questions to ask returned traveller

Where have they been, when did they arrive and depart, onset of symptoms
Anyone else unwell they travelled with
Activities - Swimming/sex/animal contact/rural trip
Contaminated food/water/accomodation
Any precautions taken

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Findings on examination

Fever, rash, hepatosplenomegaly, lymphadenopathy, insect bites, wounds

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Infection control for returned travellers

Infection control, PPE recommended

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Causes of bloody diarrhoea

E.ColiO157 or Amoebic colitis. Can also be campylobacter, salmonella, shigella

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Profuse watery diarrhoea

Cholera, often associated with outbreaks in refugee caps

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Cruise ships

Norovirus and Rotavirus

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Investigation of travellers diarrhoea

Stool culture

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Treatment for acute travellers diarrhoea

Supportive - Fluid rehydration (oral/IV)
Fluoroquinolone (Ciprofloxacin) single dose may stop worsening - 3-day course is recommended
Due to antibiotic resistance in Asia, macrolide such as Azithromycin may be more useful

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Typhoid vs parathyphoid fever

Typhoid fever is casued by Salmonella typhi whereas parathyphoid fever is milder and caused by Salmonella paratyphi. They are both enteric fevers

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Common cause of enteric fever in travellers returning from Indian subcontinent

Salmonella

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Vaccination in enteric fever

Protection against typhoid no protection against paratyphoid

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Investigating jaundice and fever

Blood film for malaria antigen, red cell fragmentation, FBC, LFT, UE, coagulation, blood cultures, US abdomen, serological test for viruses

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Management and treatment of fever and jaundice

Supportive - Electrolyes, fluids, isolation, might need antibiotics

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What causes amoebiasis

Entamoeba histolytica, faecal-oral spread

Associated with poor sanitation

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Symptoms of amoebiasis

Amoebic dysentry - abdominal pain, fever, bloody diarrhoea, collitis, peritonism

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Investigating amoebiasis

Stool microscopy, may have cysts
AXR - Toxic megacolon
Endoscopy for biopsy

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Complication of amoebiasis

Amoebic liver abscess

Manage with Metronidazole or TInidazole

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What causes giardiasis

Giardia intestinalis - Flagellated protozoa

Invades duodenum and proximal jejunum

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Symptoms of giardiasis

Watery, malodorous diarrhoea, bloating, flatulence, abdominal cramps, weight loss

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differentiate amoebiasis and giardiasis

Amoebiasis has bloody diarrhoea whereas giardiasis has watery, malodorous diarrhoea

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Treatment of giardiasis

Metronidazole or Tinidazole (5-day course)

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Investigating giardiasis

Stool microscopy for cysts (often difficult)

Prefer PCR

How are helminth infections often diagnosed

Adult worm passed or eggs in stool

Most common parasitic infection

Ascariasis by intestinal nematodes (roundworms)

Lifecycle of intestinal nematodes

Egg ingested, hatch in small intestine, invade gut wall into venous system. Travel via liver and heart to the lungs. These break into alveoli, ascend tracheobronchial tree then swallowed into gut to develop into adults and release eggs.

Common termatodes (flukes) infection in SE asia

Liver flukes called Clonorchis or Fasciola

How can termatodes cause portal hypertension

Adult worms located in portal venules which can lead to hepatomegaly, liver fibrosis and portal hypertension

Common cause of tapeworm contamination

Uncooked/undercooked pork or beef

What can cause cysticercosis

Taenia solium (flatworm) eggs, tissue cysts in muscle and brain often producing seizures

What causes chagas disease

Trypanasoma cruzi a protozoan. Spread by the kissing bug triatome.

Symptoms of chagas disease

Change over course of disease. Early stage may be asymptomatic or milk with fever, swollen lymph nodes, headaches or local swelling at site of bite. Can cause enlargement of heart ventricles, heart failure, enlarged oesophagus or enlarged colon

Risk factors for STI

<25 years old, non-condom user, multiple sexual partners, MSM, past history of STI

A 38-year old man presents with a two day history of anal discharge and occasional bleeding. He also has a urethral discharge. He has a regular male partner of 2 years with whom he has regular condomless anal sex (receptive and insertive). He last had sex with another male partner 1 week ago. They had oral sex only.

Differential - Inflammatory bowel disease STI such as Chlamydia, Gonorrhoea, Lymphogranuloma venereum

What causes lymphogranuloma venereum

The invasive serotype of Chlamydia trachomatis | Infection of lymphatics and lymph nodes

What causes rectal gonorrhoea

Neisseria gonorrhoea | Transmitted via direct contact of the mucosal surface

Recent anal sex with symptoms of lower abdominal pain, diarrhoea, anal discharge, tenesmus, rectal bleeding, urethral/vaginal discharge, dysuria

Rectal gonorrhoea

Chlamydia infection stages

Chlamydia has two developmental stages - elementary body (EB) and reticulate body (RB). EB is infectious form of Chlamydia. Contain a rigid outer membrane that bind to receptors on host cells. Intracellularly, they transform to RB where they undergo replication. This RB converts back to EB and is released through reverse endocytosis

Why does Chlamydia resist intracellular killing

Elementary body (EB), infectious form of Chlamydia, have a rigid outer membrane that inhibits fusion of endosome and lysosome and resist intracellular killing

Endoscopic examination of rectal gonorrhoea

Purulent discharge and inflamed mucous

Treatment of rectal chlamydia

Azithromycin and doxycycline (better clearance at rectal site), STI testing, public health interventions

Syphilis management

STI screening Benzathene penicillin Public health intervention Follow-up serology

What causes Syphilis

Troponema pallidum

How can Syphilis be diagnosed

Via dark field microscopy

Stages of Syphilis

Primary - Solitary painless ulcers around genitals, anus or mouth Secondary - Diffuse rash involving palms of the hands, soles of feet and possibly in mouth or vagina Latent - Few or no symptoms Tertiary - Gummas, neurological or heart symptoms

Common cause of HSV proctitis

Herpes Simplex Virus 2

Symptoms of HSV

Ulcers, pain, painful defaecation, bleeding, mucus, viraemic symptoms

Transmission of HSV and HPV

Ano-genital or oro-anal

Symptoms of Human Papilloma Virus

Anal warts, anal intraepithelial neoplasia and anal cancer

Lymphogranuloma venereum is associated with

``` MSM, often HIV+ Group sex Drug use Syphilis Hepatitis C ```

Clinical features of lymphogranuloma venereum

Primary (3-30 days) - Ulcers Secondary (3-6/12) - Inguinal syndrome, ano-rectal syndrome Tertiary - Strictures, fistulae, genital elephantiasis

What is a test-of-cure

Repeat testing 3-4 weeks after completing therapy to detect therapeutic failure

Who do we test for lymphogranuloma venereum

MSM with haemorrhagic proctitis HIV+ MSM with positive rectal chlamydia Failed chlamydia test of cure Contact of lymphogranuloma venereum

Person diagnosed with lymphogranuloma venereum should be also tested for

HIV, Syphilis, Hepatitis C

Why should STI testing be performed at all sexual sites

As STI often co-exist