Travel Related Infections Flashcards
Why are travellers vulnerable 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)
What infections are common worldwide?
- Influenza
- Community acquired pneumonia
- Meningococcal disease
- Sexually transmitted diseases
Give examples of climate/environmental relayed health problems.
- Sunburn
- Heat exhaustion and heatstroke
- Fungal infections
- Bacterial skin infections
- Cold injury
- Altitude sickness
What infections are controllable by public heath measures regarding sanitation??
- Travelers’ diarrhoea
- Typhoid
- Hepatitis A or E
- Giardiasis
- Amoebiasis
- Helminth infections
- Viral gastroenteritis
- Food poisoning
- Shigella dysentery
- Cholera
- Cryptosporidiosis
What infections are controllable by public heath measures regarding immunisations?
- Poliomyelitis
- Diphtheria
What infections are controllable by public heath measures regarding education?
- HIV
- STDs
Give examples of water-related infections
- Schistosomiasis
- Leptospirosis
- Liver flukes
- Strongyloidiasis
- Hookworms
- Guinea worms
Give examples of arthropod-borne infections.
- 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)
Give some examples of some 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
Give examples of some important tropical disease to be aware of.
- Malaria
- Typhoid
- Dengue Fever
- Schistosomiasis
- Rickettsiosis
- Viral haemorrhagic fevers
- Zika fever
What is the epidemiology of malaria?
United Kingdom (HPA, 2015)
- 1400 cases/year
- 6 deaths/year
Worldwide (WHO, 2012)
- 207 million cases/year
- 627,000 deaths/year
What is the malaria vector?
The female anopheles mosquito
Describe the lifecycle of malaria.
- Mosquito bites human and injects sporozoites that migrate to the liver
- Sporozoites become merozoites
- Merozoites enter circulation with RBC and mature to male and female gametocytes
- Gametocytes for zygotes which mature to sporozoites
- Sporozoites transferred to mosquito when they bite humans
What are the 5 species of malaria?
Potentially severe
-Plasmodium falciparum
Benign
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
- Plasmodium knowlesi
What symptoms can malaria present with?
- Fever
- Rigors
- Aching bones
- Abdominal pain
- Headache
- Dysuria
- Frequency
- Sore throat
- Cough
What signs can malaria present with?
- None
- Splenomegaly
- Hepatomegaly
- Mild jaundice
What are the possible complications of malaria?
- Cerebral malaria (encephalopathy)
- Blackwater fever
- Pulmonary oedema
- Jaundice
- Severe anaemia
- Algid malaria
How does cerebral malaria present?
- Hypoglycaemia
- Convulsions
- Hypoxia
How does Blackwater fever present?
- Severe intravascular haemolysis
- High parasitaemia
- Profound anaemia
- Haemoglobulinuria
- AKI
What is algid malaria?
Gram negative septicaemia
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 the severity of malaria assessed?
Complicated malaria= 1 or more:
- Impaired consciousness or seizures
- Hypoglycaemia
- Parasite count 2% or higher
- Haemoglobin 8mg/dL or less
- Spontaneous bleeding / DIC
- Haemoglobinuria
- Renal impairment or pH <7.3
- Pulmonary oedema or ARDS
- Shock (algid malaria)
What are the treatment options for uncomplicated P, falciparum malaria?
- Riamet (3 days)
- Euartesim (3 days)
- Malarone (3 days)
- Quinine (7 days) plus oral doxycycline or clindamycin
What are the possible side effects of oral quinine?
- Nausea
- Tinnitus
- Deafness
- Rash
- Hypoglycaemia
What are the treatment options for complicated or severe P falciparum malaria?
- IV artesunate
- IV quinine plus oral doxycycline or clindamycin
What are the possible side effects of IV quinine?
- Cardiac depression
- Cerebral irritation
- N+V
How is malaria caused by organisms other than P falciparum treated?
- Chloroquine (3 days)
- Riamet (3 days)
- Add primaquine (14 days) in vivax and ovale to eradicate liver hypnozoites
What programmes are there in place to control malaria?
- Drainage of standing water to prevent mosquito breeding sites
- Larvacides
- Mosquito killing sprays
- Human behaviour including bed nets and mesh windows
What organisms cause typhoid (enteric) fever?
- Salmonella typhi
- Salmonella paratyphi
What is the epidemiology of typhoid?
- Global cases: 27 million infections/yr
- Global deaths:over 200,000/yr
- UK cases: 500/yr
What conditions make typhoid more likely?
- Poor sanitation
- Unclean drinking water
What is the incubation period for typhoid?
7-28 days
What are the clinical features of typhoid within the 1st week?
- Fever
- Headache
- Abdominal discomfort
- Constipation
- Dry cough
- Relative bradycardia
- Neutrophilia
- Confusion
What are the clinical features of typhoid in the 2nd week?
- Fever peaks at 7-10 days
- Rose spots
- Diarrhoea begins
- Tachycardia
- Neutropenia
What are the clinical features of typhoid in the 3rd week?
- Intestinal bleeding
- Perforation
- Peritonism
- Metastatic infections
What are the clinical features of typhoid in week 4?
- Usually recovery
- 10-15% relapse
How is typhoid fever diagnosed?
- Clinically not easy due to evolution of features
- Culture of blood, urine and stool
- Culture of bone marrow
What is the treatment for typhoid fever?
- Oral azithromycin
- IV ceftriaxone
What is the commonest human arbovirus infection?
Dengue
What is the epidemiology of Dengue fever?
- Dengue infection: 100 million cases/year
- Dengue Deaths: 25,000/year
What is the vector in dengue?
Aedes aegypti (mosquito)
What is the classical presentation of dengue?
- Sudden fever
- Severe headache, retro-orbital pain
- Severe myalgia and arthralgia
- Macular/ maculopapular rash
- Haemorrhagic signs: petechiae, purpura, positive tourniquet test
How is dengue diagnosed?
Clinically
- Thrombocytopenia
- Leucopenia
- Elevated transaminases
- Positive tourniquet test
Laboratory
- PCR
- Serology
How is dengue managed?
No specific therapeutic agents
What are the possible complications of dengue?
- Dengue haemorrhagic fever (DHF)
- Dengue shock syndrome (DSS)
How are the complications associated with dengue managed?
- IV fluids
- Fresh frozen plasma
- Platelets
How is dengue prevented?
- Avoid bites
- New vaccine but limited use
What vectors are involved in schistosomiasis?
- S. haematobium
- S. mansoni
- S. japonicum
How is schistosomiasis transmitted?
Freshwater snails
Describe the lifecycle of schistosomiasis.
- Vectors excreted by infected human in faeces and urine enter freshwater
- Eggs hatch releasing miracidia which penetrate the snails tissues.
- Mature as sporocytststs in snail and cercariae are released into the water and penetrate human skin
- They lose their tail and enter the circulation as schistosimulae
- Migrate to portal blood in liver and mature into adults
- Adults pair and migrate toe bowel to lay eggs which are then excreted by the infected human
What are the clinical features of schistosomiasis?
Swimmers Itch (1st few hrs) -Clears 24-48hrs
Invasive stage (after 24hrs) -Cough, abdominal 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
How is schistosomiasis diagnosed?
- Clinical diagnosis
- Antibody tests
- Ova in stools and urine
- Rectal snip
How is schistomiasis treated?
PRAZIQUANTEL
-20mg/kg, two doses 6hrs apart
Prednisolone
-If severe
What doe rickettsiosis cause?
Tick typhus
What are the vectors involved in tick typhus?
- R. conorii
- R. africae
What are the clinical features of tick typhus?
- Abrupt onset of swinging fever
- Headache
- Confusion
- Endovasculitis
- Rash (macular, petechial)
- Bleeding
How is tick typhus diagnosed?
- Clinical features
- Serology
How is tick typhus treated?
Tetracycline
Give some examples of viral haemorrhagic fevers.
- Ebola
- Congo-Crimea haemorrhagic fever
- Lassa fever
- Marburg disease
What is the incubation of viral haemorrhagic fevers?
-Maximum incubation period is 3 weeks
How should people with viral haemorrhagic fevers be managed?
- High security infection unit in isolation
- Supportive treatment
What pathogen causes zika?
Flavivirus
How is zika transmitted?
- Daytime biting aedes mosquitoes
- Sexual contact with infected or infected blood transfusion
What conditions is zika related to?
- Dengue
- Yellow fever
- Jap B encephalitis
- West Nile virus
How can zike present?
- No or mild symptoms
- Headache
- Rash
- Fever
- Malaise
- Conjunctivitis
- Joint pains
What can zika virus cause in pregnancy?
Microcephaly and other neurological problems
How is zika managed?
- No current antiviral therapy
- Vaccines in development
- Prevention through mosquito control measures
What autoimmune condition can zika cause?
Guillain Barre syndrome
What is the most common cause of fever in a returning traveller?
Malaria
How can you narrow down your diagnosis when taking a history?
- Is it tropical?
- Travel history
- Precautions taken
- Risks
- Symptoms
- Incubation periods
What traveller disease would a rash suggest?
- Typhoid
- Typhus
- Dengue
What traveller disease would jaundice suggest?
- Hepatitis
- Malaria
- Yellow fever
What traveller disease would enlarged lymph nodes suggest?
- Leishmania
- Trypanosomiasis
What traveller disease would hepatomegaly suggest?
- Malaria
- Typhoid
- Amoebic abscess
What traveller disease would splenomegaly suggest?
- Visceral leishmaniasis
- typhoid
- Malaria
What investigations should be carried out on a traveller returning with fever?
- FBC
- Malaria films
- LFTs
- Stool microscopy & culture
- Urine analysis & culture
- Blood culture(s)
- CXR
How should travellers returning with fever be treated?
- Isolation and use of PPE
- Supportive measures
- Empirical treatment if patient is unwell and based on the likely diagnosis
- Specific treatment once diagnosis is established
