Travel related infection Flashcards
Who is the “father of Tropical Medicine” ?
Sir Patrick Manson MBChB, Aberdeen 1865:
> Discovered cause of Filariasis (Elephantiasis)
> Founded London School of Tropical Medicine
Unfamiliar features of imported diseases?
> Presenting features > Isolation requirements > Diagnostic methods > Treatment/Management > Unexpected complications
Vulnerability of travelers to infection?
> Temptation to take risks away from home:
- food, water
- animals
- sex
> Different epidemiology of some diseases:
- HIV
- TB
- polio
- diphtheria
> Incomplete understanding of health hazards
> Stress of travel
> Refugees: deprivation, malnutrition, disease, injury
Infections which are common worldwide?
> Influenza
Community-acquired pneumonia
Meningococcal disease
Sexually transmitted diseases
Climate or environment related health problems when travelling??
> Sunburn > Heat exhaustion and heatstroke > Fungal infections > Bacterial skin infections > Cold injury > Altitude sickness
Water-related infections when travelling?
> Schistosomiasis > Leptospirosis > Liver flukes > Strongyloidiasis > Hookworms > Guinea worms
Arthropod-borne infections when travelling?
> Malaria (mosquitos)
Dengue fever (mosquitos)
Rickettsial infections (ticks: typhus)
Leishmaniasis (sand flies: Kala-azar)
Trypanosomiasis (tsetse fly: sleeping sickness)
Filariasis (mosquitoes: elephantiasis)
Onchocerciasis (black flies: River Blindness)
Which arthropod causes malaria?
Mosquitos
Which arthropod causes dengue fever?
Mosquitos
Which arthropod causes typhus (rickettsial infection)?
Ticks
Which arthropod causes kala-azar (Leishmaniasis)?
Sand flies
Which arthropod causes sleeping sickness (trpanosomiasis)?
Tsetse fly
Which arthropod causes elephantiasis (filariasis)?
Mosquitos
Which arthropod causes river blindness (onchocerciasis)?
Black flies
Emerging Infectious Diseases worldwide?
> Zika: Latin America, Caribbean > Ebola virus disease: West Africa > MERS-CoV: Middle East > Swine ‘flu (H1N1): worldwide > Avian ‘flu (H5N1 and H7N9): China > SARS: Far East, worldwide West Nile Virus: USA …etc.
Important Tropical Diseases?
> Malaria > Typhoid > Dengue Fever > Schistosomiasis > Rickettsiosis > Viral haemorrhagic fevers > Zika fever
Malaria epidemiology?
> United Kingdom (HPA, 2015)
- 1400 cases/year
- 6 deaths/year
> Worldwide (WHO, 2012)
- 207 million cases/year
- 627,000 deaths/year
The Malaria vector?
female Anopheles mosquito
What is the malaria life cycle?
1) Mosquito bites human
2) Delivers sporozoite
3) Taken up by liver cells
4) Merozoites produced
5) Taken up into RBC
6) Destroys RBCs
7) Bite by mosquito
8) Female gametocyte taken up by mosquito
9) Gametocyte –> Zygote –> Sporozoite
10) Next human bitten
11) Sporozoite delivered
What are the 5 malaria species?
Potentially severe:
- Plasmodium falciparum
Benign:
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
- Plasmodium knowlesi
Which malarial species in potentially severe?
Plasmodium falciparum
What are the symptoms of malaria?
SYMPTOMS:
- fever
- rigors
- aching bones
- abdo pain
- headache
- dysuria
- frequency
- sore throat
- cough
What are the signs of malaria?
SIGNS:
- none
- splenomegaly
- hepatomegaly
- mild jaundice
What are the complications of malaria?
1) Cerebral malaria (encephalopathy):
- non- immune visitors
- children in endemic areas hypoglycaemia, convulsions, hypoxia
2) Blackwater fever:
- severe intravascular haemolysis
- high parasitaemia
- profound anaemia
- haemoglobinuria
- acute renal failure
3) Pulmonary oedema
4) Jaundice
5) Severe anaemia
6) Algid malaria:
- Gram-negative septicaemia
What are the complications of malaria - Cerebral malaria (encephalopathy)?
Cerebral malaria (encephalopathy):
- non- immune visitors
- children in endemic areas hypoglycaemia, convulsions, hypoxia
What are the complications of malaria - Blackwater fever?
Blackwater fever:
- severe intravascular haemolysis
- high parasitaemia
- profound anaemia
- haemoglobinuria
- acute renal failure
Management of malaria in adults, guidelines
> UK malaria treatment guidelines 2016
Lalloo DG et al. J Infect 2016; 72: 635-649
http://dx.doi.org/10.1016/j.jinf.2016.02.001
> BNF
How is malaria diagnosed?
> Thick & thin blood films:
- Giemsa
- Field’s stain
> Quantitative buffy coat (QBC)
- centrifugation
- UV microscopy
> Rapid antigen tests:
- OptiMal
- ParaSight-F
How is severity is malaria assessed?
Complicated malaria in one or more of:
> Impaired consciousness or seizures
> Hypoglycaemia
> Parasite count 2%
> Haemoglobin 8mg/dL
> Spontaneous bleeding / DIC
> Haemoglobinuria
> Renal impairment or pH <7.3
> Pulmonary oedema or ARDS
> Shock (algid malaria)
?Gram negative bacteraemia
Natural drugs used in malaria treatment?
> Quinine from Chinchona
> Artemisinins from Quinghaosu
Treatment options for uncomplicated P. falciparum malaria?
Riamet ® (artemether-lumefantrine) 3 days
Eurartesim ® (dihydroartemisinin-piperaquine) 3 days
Malarone ® (atovaquone-proguanil) 3 days
Quinine 7 days
S/E nausea, tinnitus, deafness (cinchonism), rash, hypoglycaemia
plus oral doxycycline (or clindamycin)
Treatment options for complicated P. falciparum malaria?
1) IV artesunate (unlicensed in UK)
2) IV quinine
(S/E cardiac depression, cerebral irritation, N&V)
plus oral doxycycline (or clindamycin)
When patient is stable & able to swallow, switch to oral treatments
Treatment of
P. vivax, P. ovale, P. malariae, P. knowles?
chloroquine 3 days
Riamet ® (artemether-lumefantrine) 3 days
add primaquine* (14 days) in vivax and ovale, to eradicate liver hypnozoites
*check for G6PD deficiency
Malaria Control Programmes?
Mosquito breeding sites:
- Drainage of standing water
Larvacides:
- (Paris green)
- temphos
- biological
Mosquito killing sprays:
- DDT
- malathion, (dieldrin)
Human behaviour:
- Bed nets
- Mesh windows
Pathogen that causes typhoid (enteric) fever?
Salmonella typhi
Salmonella paratyphi
Typhoid (Enteric) fever epidemiology?
Global cases: 27 million infections/yr
Global deaths: over 200,000/yr
UK cases: 500/yr
What is the main cause of widespread Typhoid (Enteric) fever?
- Poor sanitation
- Unclean drinking water
Typhoid Fever: Clinical features?
> Incubation period: 7 days - 4 week
> 1st week:
fever, headache, abdo. discomfort, constipation, dry cough, relative bradycardia, neutrophilia, confusion
> 2nd week:
fever peaks at 7-10 days, Rose spots, diarrhoea begins, tachycardia, neutropenia
> 3rd week (Complications):
intestinal bleeding, perforation, peritonism, metastatic infections
> week 4 (Recovery):
10 - 15% relapse
What is the incubation period of typhoid fever?
7 days - 4 week
What occurs within the 1st week of typhoid fever?
> fever > headache > abdomen discomfort > constipation > dry cough > relative bradycardia > neutrophilia > confusion
What occurs within the 2nd week of typhoid fever?
> fever peaks at 7-10 days > Rose spots > diarrhoea begins > tachycardia > neutropenia
What occurs within the 3rd week of typhoid fever?
3rd week (Complications): > intestinal bleeding > perforation > peritonism > metastatic infections
What occurs within the 4th week of typhoid fever?
week 4 (Recovery): 10 - 15% relapse
How is typhoid fever diagnosed?
Clinical
- not easy
- evolution of features
Laboratory (Salmonella typhi, S. paratyphi)
- Culture blood, urine & stool
- Culture bone marrow
Typhoid Fever: Treatment?
Oral Azithromycin
- now drug of choice for Asian-acquired, uncomplicated enteric fever
IV Ceftriaxone
- if complicated, or concerned regarding absorption
Increasing ciprofloxacin resistance
What is the most common human arbovirus infection?
Dengue - Swahili “Ki-Dinga pepo”
How many cases of dengue infection?
100 million cases/year
How many deaths caused by dengue each year?
25,000/year
How is dengue fever transmitted?
Aedes aegypti - Mosquito
Classical presentation of dengue fever?
> Sudden fever
> Severe headache, retro-orbital pain
> Severe myalgia and arthralgia
> Macular/ maculopapular rash / petichial rash
> Haemorrhagic signs: petechiae, purpura, positive tourniquet test
Dengue Diagnosis?
Clinical
- Thrombocytopenia
- Leucopenia
- Elevated transaminases
- Positive tourniquet test
Laboratory: PCR, serology
Dengue Management?
No specific therapeutic agents
Complications
- Dengue haemorrhagic fever (DHF)
- Dengue shock syndrome (DSS)
- Rx: IV fluids, fresh frozen plasma, platelets
Prevention
- avoid bites
- new vaccine (Dengvaxia), 2016; limited use
Complications of Dengue fever and how to manage?
Complications
- Dengue haemorrhagic fever (DHF)
- Dengue shock syndrome (DSS)
- Rx: IV fluids, fresh frozen plasma, platelets
Sources of Schistosomiasis?
- Fresh water
- Freshwater snails
Species of Schistosomiasis?
S. haematobium
S. mansoni
S. japonicum
Lifecycle of Schistosomiasis?
1) Schistosomiasis from Faeces or urine
2) Eggs hatch releasing miracidia
3) Miracidia penetrate snails tissue
4) Sporocysts in snail (successive generations)
5) Cercariae released by snails into water and free-swimming (Infective stage)
6) Penetrate skin
7) Cercariae lose tails during penetrating and becoming schistosomulae
8) Circulation
9) Migrate to portal blood in liver and mature into adults
10) Paired adult worms migrate to mesenteric venules of bowel/rectum (Eggs released in stools)
Schistosomiasis - Clinical features?
Swimmers Itch (1st few hrs) - clears 24-48hrs
Invasive stage (after 24hrs) - cough, abdo discomfort, splenomegaly, eosinophilia
Katayama Fever (after 15-20 days): - prostrate, fever, urticaria, lymphadenopathy, splenomegaly, diarrhoea, eosinophilia
Acute disease (6-8 weeks) eggs deposited in bowel (dysentery) or bladder (haematuria)
Chronic disease
Schistosomiasis - Clinical features, first few hours?
Swimmers itch, clears for 24-48 hours
Schistosomiasis - Clinical features, after 24 hours?
Invasive stage:
- Cough
- Abdomen discomfort
- Splenomegaly
- Eosinophilia
Schistosomiasis - Clinical features, after 15-20 days?
Katayama Fever (after 15-20 days):
- prostrate
- fever
- urticaria
- lymphadenopathy
- splenomegaly
- diarrhoea
- eosinophilia
Schistosomiasis - Clinical features, 6-8 weeks?
Acute disease (6-8 weeks) = eggs deposited in bowel (dysentery) or bladder (haematuria)
Schistosomiasis - Clinical features, after 8 weeks?
Chronic disease
Diagnosis of schistosomiasis?
Diagnosis
- Clinical diagnosis
- Antibody tests
- Ova in stools and urine
- Rectal snip
Treatment of schistosomiasis?
Treatment
- PRAZIQUANTEL 20mg/kg, two doses 6hrs apart
- Prednisolone if severe
What does Rickettsiosis cause?
> Tick typhus (R. conorii, R africae) > Rocky Mountain Spotted Fever (R. rickettsii) > Epidemic typhus (R. prowazekii) > Murine or endemic typhus (R. mooseri) > Scrub typhus (R. tsutsugamushi) > others
Which species of Rickettsiosis cause Tick typhus?
R. conorii, R africae
Which species of Rickettsiosis cause Rocky Mountain Spotted Fever?
R. rickettsii
Which species of Rickettsiosis cause Epidemic typhus?
R. prowazekii
Which species of Rickettsiosis cause Murine or endemic typhus?
R. mooseri
Which species of Rickettsiosis cause Scrub typhus?
R. tsutsugamushi
With cases of tick typhus in the UK which countries is the source usually?
- Southern Africa
- Mediterranean
- Arabian Gulf
What are the clinical features of Rickettsiosis?
Clinical features:
- Abrupt onset swinging fever
- headache
- confusion
- endovasculitis
- rash (macular, petechial)
- bleeding
How is Rickettsiosis diagnosed?
Diagnosis: clinical features, serology
How is Rickettsiosis managed?
Tetracycline
Viral haemorrhagic fever outbreaks in Congo?
Ebola, 2007
Viral haemorrhagic fever outbreaks in Sierra Leone?
Ebola, 2013-2016
Viral haemorrhagic fever outbreaks in Guinea and Liberia?
Ebola, 2013-2016
Viral haemorrhagic fever outbreaks in Glasgow?
CCHV, 2012
Ebola, 2014, 2015
Viral haemorrhagic fever in the UK?
Serious infections but rare in UK:
- Ebola
- Congo-Crimea haemorrhagic fever
- Lassa fever
- Marburg disease
What must occur if a haemorrhagic fever is diagnosed?
High security infection unit and supportive therapy
What is the cause of zika?
Flavivirus
How is Zika (flavivirus) transmitted?
Daytime-biting Aedes Mosquitos
Also sexual contact and blood transmission
What is Zika (flavivirus) related to?
- dengue,
- yellow fever
- Jap B encephalitis
- West Nile viruses
Outbreaks of Zika (flavivirus)?
> Pacific outbreak, 2013-2014
> Latin America pandemic 2015-2016
Clinical features of Zika?
Clinical, no or mild symptoms:
- headache
- rash
- fever
- malaise
- conjunctivitis
- joint pains (like dengue)
In pregnancy, can cause microcephaly and other neurological problems
Can cause Guillain-Barre syndrome
How is Zika treated?
There is no antiviral therapy
Mosquito control measures
Vaccines development
Which questions should be asked in travellers disease?
History: > Is it tropical? > Travel history > Precautions taken > Risks > Symptoms > Incubation periods
In travellers disease if there is a rash what should you consider?
- Typhoid
- Typhus
- Dengue
In travellers disease if there is a jaundice what should you consider?
- Hepatitis
- Malaria
- Yellow fever
In travellers disease if there is a lymph nodes what should you consider?
- Leishmania
- Trypanosomiasis
