JC90 (Microbiology) - Fever in the traveller Flashcards by Max Kam

Factors that influence level of travel risks

 Destination of travel, standards of accommodation and food hygiene
 Season of travel
 Duration of stay

 Exposure: purpose and nature of travel, behaviour of the traveler (e.g. sex tourism)

 Pre-existing health of the traveler, e.g. children, infants, the elderly, pregnant women, persons with disabilities, persons with chronic medical illnesses

 Pre-travel preparations

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List environmental and infection risk to travelers

Environmental risks, e.g.:
 Accidents, motion sickness, travel by air
 Altitude
 Heat stroke and heat exhaustion, humidity, exposure to cold
 Ultraviolet radiation from the sun, foodborne and waterborne health risks (e.g. drowning)
 Animals, insects

Infections, e.g.:
 Foodborne and waterborne diseases
 Vector borne diseases, zoonoses
 Sexually-transmitted diseases, bloodborne infections
 Airborne diseases
 Diseases transmitted from soil and water

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Preventive measures against health risk during travels

Medical counselling before travel:

Assess health risks associated with travel
vaccinations, antimicrobial prophylaxis; usual medications

Precautions during travel:

Education and counselling on prevention of foodborne, waterborne, vectorborne diseases and other health risks
Medical kit

Follow-up after travel if

chronic disease
Illness after return
exposed to serious infectious disease
> 3 months in a developing country

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Outline history taking for a returning traveler with illness

Present illness:

Onset, incubation period
Duration
Symptomatology
Fever pattern

Travel history:
- dates and destinations

Contact history:

Sexual exposure, sexual history
Needle and blood exposure: drugs, tattoos, piercings, injections..etc
Animal/ arthropod contacts
Exposure to unclean water
Food and drink exposure (swimming, walking, rafting)

Prophylactic measures (antibiotics, insect repellants)

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Common pathogens associated with ingestion of raw/ uncooked food

Enteric infections (foodborne, waterborne infections):
 Traveller’s diarrhea
 Dysentery (bacillary Shigella, amoebic infection)
 Hepatitis A, E
 Enteric fever (incl. typhoid salmonellosis)
 Cholera (Vibrio)
 Giardiasis (parasite)

 Others: EHEC, campylobacteriosis, brucellosis, listerosis,
toxoplasmosis, protozoal and helminth infections (amoebiasis),
Norovirus

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Common pathogens associated with arthropod bites

 Malaria
 Dengue
 Japanese encephalitis, Hemorrhagic fevers
 Zika virus infection, chikungunya, rickettsioses
 Relapsing fevers, babesiosis, trypanosomiasis, dirofilariasis

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Common pathogens associated with blood/ body fluid exposure

e.g. sex, blood, body fluids, transfusion, surgery, IVDU, Tattoos, body piercing

Sexually-transmitted diseases e.g. syphillis
bloodborne viruses: HIV
hepatitis B/C
non-tuberculous mycobacterial

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Common pathogens associated with fresh water contact

 Leptospirosis (unculturable)

 Schistosomiasis (Katayama fever), legionellosis (respiratory tract infection)

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Common pathogens a/w contaminated soil exposure

Histoplasmosis, coccidioidomycoses, other endemic mycoses, cutaneous larva migrans, strongyloidiasis (helminth)

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Common pathogens a/w rodents contact

Rodents 
 Leptospirosis
 Plaque, rat-bite fever
 Hantavirus infections
 Hemorrhagic fevers
(e.g. Lassa fever, Crimean-Congo)

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Common pathogens a/w wild animal contact/ bites

 MERS-CoV infection (travel history to Middle East, contact history with camels)
 Herpes B virus infection, Q fever, brucellosis, tularaemia, anthrax, psittacosis, avian influenza
 Bite wound infections
 Rabies, bat rabies

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Common pathogens a/w overseas hospitalization

antibiotic-resistant organism (colonization/ infection):

Bacteria: ESBL-, carbapenemase-producing Enterobacteriaceae
MRSA, VRE, multidrug-resistant Acinetobacter baumannii, Pseudomonas aeruginosa

Multi-resistant Candida auris

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Outline physical exam for a returning traveler with illness

General:
o Skin lesions (rash, eschar, bite marks, needle marks)
o Jaundice
o Bleeding tendencies (gum, ecchymosis)

Systemic, e.g. lymphadenopathy, organomegaly, localizing signs

** Must perform head-to-toe examination with absolute exposure **

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First-line investigations for returning traveler with illness

Haematological: cell counts, differential, coagulation studies

Biochemistry: liver, kidney, creatine kinase

Radiological imaging: X-ray, CT (e.g. abdomen, brain), MRI (as indicated)

Microbiological:
o Microscopy (e.g. parasites): blood film, stool
o Culture: blood, stool, urine, tissues, sputum
o Serology (Ab response may not be positive in acute stage)

Tissue biopsy: microbiology, histopathology

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4 key questions for formulating differential diagnosis of sickness after travel?

4 key questions:
 Based on geographical areas visited: any epidemic or pandemics, any local outbreaks, any antibiotic resistance

 Based on the time of travel (incubation periods)?

 What activities, exposures, host factors, clinical and laboratory findings?

 What is/are treatable, transmissible, or both?
o Ebola: put to isolation ward
o Malaria is treatable

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Framework for management of infectious disease emergency (returning traveler)

Must exclude Hemorrhic signs: meningococcal, Gram-ve bacteraemia, viral hemorrhagic fever
Exclude malaria: serial thick smears to confirm malaria + empirical therapy if end-organ damage

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Malaria

Etiology/ vector
Transmission

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5 Plasmodium species (= blood protozoa, parasite):
 P. vivax (commonest)
 P. falciparum (commonest): most fulminant form of disease (= medical emergency, rapidly fatal
 P. malariae
 P. ovale
 P. knowlesi (only in some Southeast Asian countries)

Transmission:
From person-to-person via:
 Bites of female Anopheles mosquitoes*;
 Blood transfusion (occasionally)

Malaria

Incubation period
Symptoms and signs

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Incubation: Unexplained fever that starts after the 7th day of visit in
an endemic area

S/S with highest frequency of presentation:

Fever
Rigor/ Shivering
Headache
Vomiting
Arthralgia/ myalgia
Diarrhea

Falciparum malaria infection infectious emergency, deadly

Presentation

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Dead in a day!

 Impaired consciousness
 Shock

 Renal impairment, acidosis, hypoglycaemia

 Severe malarial anaemia and jaundice

 Significant bleeding

 Pulmonary oedema

 Hyperparasitaemia (P. falciparum, >10%)

Malaria

Diagnostic tests (3)

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Demonstrate Plasmodium in stained blood smear

Must have >3 smears
Peripheral blood or marrow blood in thick and thin films
Measure parasitaemia

Plasmodial antigens test with immunochromatographic kits (rapid)

PCR for Plasmodium spp. in blood

Blood smear for malaria

How many smears?
Cause of false negative smear?

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At least 3 smears over 48 hours

one negative blood smear does not exclude malaria

False negative smear: received prophylaxis or partial treatment

Falciparum malaria

Endemic areas
Treatment options

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Endemic and resistant in Central Africa and SE asia

Treatment options:
Severe/ falciparum malaria:
 Artemisinin-based therapy (e.g. iv artesunate)
 Quinine

Other options:
 Atovaquone-proguanil
 Quinine + doxycycline
 (Mefloquine)

Falciparum malaria

Preventive measures: exposure and chemoprophylaxis

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Chemoprophylaxis: start up to 3 weeks before and end up to 4 weeks after travel
 Atovaquone-proguanil (Malarone®)
 Doxycycline
 (Mefloquine)

Exposure:
o Long-sleeve shirts, bednets
o Proper use of insect repellents, e.g. DEET

Dengue

causative pathogen
Transmission/ vector
Incubation period
Superimposed infections

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4 types of dengue viruses

Vectors (present in HK):
 Aedes aegypti
 Other Aedes species (e.g. Aedes albopictus)

Incubation period: 4-7 days

May superimpose other arbovirus infections (e.g. chikungunya, Zika
virus)

Dengue Definitive diagnosis methods Treatment options

Virus detection (first 5 days): o Serum for RT-PCR o Serum for virus isolation Dengue serology o NS1 antigen detection o Antibody testing (IgM) Tx: Supportive:  Symptomatic treatments  Transfusion if necessary in severe cases

Subclinical infection of Dengue Presentation

Asymptomatic/ subclinical infection Phase 1: - Sudden high fever (≥39°C), chilliness, prostration - Frontal/ retro-orbital headache, backache, muscle, joint pain - Transient **generalized macular rash in the first 24h** - **Facial flushing, eyelid puffiness, conjunctival congestion, pain on moving eyeballs** Phase 2: - Fever subsides within 3-4 days - **generalized morbilliform rash sparing palms and soles lasting for 1-5 days**

Severe dengue infection Presentation and complications

1. Dengue haemorrhagic fever (DHF) 2. Dengue shock syndrome (DSS) Presentation: severe bleeding tendency: Epistaxis, petechiae, oozing at intravenous drip sites, purpura, gastrointestinal bleeding, internal bleeding

Enteric fever Causative pathogens Transmission

 Typhoid fever: Salmonella enterica serotype Typhi  Paratyphoid fever: Salmonella enterica serotype Paratyphi A, B, C Others: Yersinia enterocolitica, Brucella, Campylobacter fetus Transmission: faecal-oral route (contaminated water, food)

Enteric fever Presentation Complications

Symptomatology:  **Persistent fever**, diarrhea but not dysentry  Relative bradycardia, **rose spots** Complications (generally preventable by early and appropriate treatment):  Intestinal perforation, intestinal haemorrhage, coma  Disseminated intravascular coagulation

Enteric fever First-line and diagnostic Investigations

 Blood culture: positive in ~90% of early cases  Stool culture: usually lower yield  Serology: A. Paired sera: rising antibody titre B. The Widal’s test (for negative culture)

Enteric fever Treatment options Prophylaxis options

 3rd-generation cephalosporins (ceftriaxone,cefotaxime)  Fluoroquiniolones (resistance increasing)  Azithromycin Prevention:  Ensure food and water hygiene  Vaccines

Traveler's diarrhea Causative pathogen

Mainly bacterial: o Especially enterotoxigenic E. coli (ETEC) o Other enteric pathogens (e.g. Campylobacter jejuni, Salmonella, Shigella) Norovirus (think cruise ship outbreak)

Traveler's diarrhea Risk factors Incubation period

30-50% travellers from industrialized to developing countries ``` Risk depends on: o Destination o Country of origin o Travel behaviour: accommodation, food, standard of hygiene, food habits, etc. At-risk populations: o Hypo-/ achlorhydria o Extremes of age o Immunosuppressed: HIV/AIDS, steroids, transplant recipients, etc. ``` Incubation:  90% in the first 2 weeks  Mean duration: 3-4 days

Traveler's diarrhea Management options Prevention options

Mx:  Fluid and electrolyte replacement: oral rehydration solution  Symptomatic treatment: loperamide for watery diarrhea ONLY  Empirical antimicrobial therapy: E.g. bismuth subsalicylate, rifaximin, ciprofloxacin, azithromycin ``` Prevention:  Pre-travel counselling and education  Behavioural modification/precautions  Vaccination for Cholera  Pharmacological (antimicrobial) prophylaxis e.g. bismuth subsalicylate, rifaximin ```

Amoebiasis 2 clinical entities and various presentations Complications

Intestinal disease:  Asymptomatic infection  Symptomatic non-invasive infection: abdominal pain, diarrhoea  Amoebic colitis with dysentery Extraintestinal disease:  Commonest = amoebic liver abscess in right lobe of liver (79-95%)  Other abscesses: pleuropulmonary abscess, pericardial abscess, brain abscess Complications: perforation of colon, toxic megacolon, amoeboma (amoebic granuloma), perianal ulceration

Extra-intestinal amoebic liver abscess - Typical presentation (with or without diarrhea or dysentery?) - Treatment

amoebic liver abscess: rarely presents with dysentry and diarrhea o 20% have history of dysentery o 10% have diarrhea/ dysentery at the time of diagnosis Treatment: metronidazole + diloxanide furoate (or another suitable luminal agent)

Case scenario

 HT, obstructive sleep apnoea, gout  Been to Africa for 3 years, previously to South Africa; travelled to Central African Republic twice in recent year  12.8.2016: fever + chills: seen by GP, given oral cefuroxime axetil + doxycycline  14.8.2016: admitted o Low WBC, lymphopenia, low platelets o Renal impairment, elevated liver enzymes

Case scenario  HT, obstructive sleep apnoea, gout  Been to Africa for 3 years, previously to South Africa; travelled to Central African Republic twice in recent year  12.8.2016: fever + chills: seen by GP, given oral cefuroxime axetil + doxycycline  14.8.2016: admitted o Low WBC, lymphopenia, low platelets o Renal impairment, elevated liver enzymes What is the most likely infectious disease and immediate investigation?

Malaria ``` Investigation for malaria: 3 blood smears Antigen test against plasmodial antigens PCR for plasmodium spp. Parasitaemia level in blood ```

``` Patient 5 (M/66):  Travelled to India for 2 months (Oct to Nov, 2004), returned 3 weeks ago  Had on and off diarrhea while in India, treated by local doctors  Admitted 10.12.2004 for fever, chills, rigor, abdominal pain, watery diarrhea  Deranged liver function ``` What pathogen can cause relapse of diarrhea and affect the liver?

Entamoeba histolytica (metronidazole + luminal agent (e.g. diloxanide furoate))

Patient 4 (M/23, Scottish, good past health):  DOA 9.4.2011  Traveled to Nepal  Fever and chills  Diarrhea: 5 bowel motions in the past 1 day, loose stool: no blood/ mucus (not dysentry)  Mosquito bites ++, been to forestry areas  2 persons in the hotel and some friends had fever + diarrhea Most likely Dx

Enteric fever Exclude other causes as appropriate (remember malaria and other infections (e.g. dengue) can present with diarrhea)

Patient 3 (F/27 recently unemployed):  Travelled to Cambodia for 2 weeks  Developed fever 2 weeks after returning to HK (longer incubation period)  Noted to have diarrhoea after admission  Pulse-temperature deficit  Mild hepatospleomegaly  CBP normal; lymphopenia (ALC = 0.6), deranged liver fuction ALT 125, ALT...  Macule at flank Most likely pathogen?

Approach: o If there is no rash: exclude malaria and other causes o But the skin is pathognomonic (rose spot: typhoid and paratyphoid) o Blood and stool culture o Serology (with paired sera)

Patient 2 (F/24 French):  Working in HK for 1 year  Admitted Jan 13  Fever and chills for ~1 week (onset ~Jan 7): o Daily fever o Peak 38-38.5oC o Malaise, decreased appetite, no skin rash  Seen by private doctor: fever did not respond to antibiotics  Traveled to Thailand almost exclusively to rural areas: countless mosquitoes bites, no prophylaxis of malaria  Diffuse general maculopapular rash blanchable Most likely causative pathogen

Diffuse general maculopapular rash blanchable o Not that of meningococcaemia: hemorrhagic, petechial, localized, nonblanchable Syndrome: fever + rash (think Dengue), Rash is not typical of malaria  Serology: dengue IGM positive  RT-PCR: dengue type 2

JC90 (Microbiology) - Fever in the traveller Flashcards

(42 cards)