Travel related infections Flashcards
What makes travelers more vulnerable to infection? [5]
- Temptation to take risks away from home (sex, food)
- Different epidemiology of some diseases
- Incomplete understanding of health hazards
- Stress of travel
- Refugees: deprivation, malnutrition
What are some climate/environmental related health problems? [4]
(Include in your list of differentials for the returning traveller)
- Sunburn, Heat exhaustion
- Fungal infections
- Bacterial skin infections
- Cold injury
- Altitude sickness
What are infections controlled by public health measures? [3] Eg sanitation immunization education
Sanitation
-Travellers diarrhoea, viral gastroenteritis, food poisoning, cholera, shigella dysentery, hep A or E
Immunisation
-Poliomyelitis, diphtheria
Education
-HIV, STDs
What are some water-related infections? [5]
- Schistosomiasis
- Leptospirosis
- Liver flukes
- Strongyloidiasis
- Hookworms
What are some arthropod borne infections? [5]
- Malaria (mosquitoes)
- Dengue fever (mosquitoes)
- Rickettsial infections (ticks)
- Leishmaniasis (sand flies)
- Filariasis (mosquitoes)
What are some important tropical diseases?
- Malaria
- Typhoid
- Dengue fever
- Schistosomiasis
- Rickettsiosis
- Viral haemorrhagic fevers
- Zika fever
Name malarial vector
What is the life cycle of malaria? [5]
Vector: female Anopheles mosquito
- Mosquito infects human
- Human carries malaria in blood
- Female mosquito bites human and now carries malaria parasite
- Reproduces and offspring also has malaria parasite
- Goes off to infect other humans
What are the 5 species of malaria parasite?
Protective factors [4]
Potentially severe
- Plasmodium falciparum
Benign
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
- Plasmodium knowlesi
Protective factors:
- Sickle cell trait
- HLA-B53
- G6PD deficiency
- Absence of Duffy antigens
What are symptoms of malaria? [7]
- Fever (alternating days), rigors
- Aching bones
- Abdo pain
- Headache
- Dysuria, frequency
- Cough, sore throat
What are signs of malaria? [4]
- Can be none: asymptomatic
- Splenomegaly
- Hepatomegaly
- Mild jaundice
What are 6 complications of malaria?
- Cerebral malaria (encephalopathy)
- Blackwater fever
- Pulm. oedema or ARDS
- Jaundice
- Severe anaemia
- Algid malaria (gram -ve septicaemia)
What blood work is required? [5]
-FBC (thrombocytosis without leucocytosis)
- U&E, LFT
-Thick and thin blood films (Giemsa, Field’s stain)
> Schizonts seen in severe malaria and parasitemia 2%
-Quantitative buffy coat (centrifugation, UV microscopy)
-Rapid antigen tests (OptiMal, ParaSight-F)
There is a severity assessment for malaria. Having ‘complicated P. Falciparum malaria’ = one or more of what? [7]
- Impaired consciousness/seizures
- Hypoglycaemia
- Parasite count at least 2%
- Haemoglobin 8mg/dL or less
- Renal impairment/pH <7.3
- Pul oedema or ARDS
- Shock (algid malaria)
What are treatment options for uncomplicated P. falciparum malaria?
artemisinin based combination therapies e.g. oral ARTESUNATE + MEFLOQUINE
What are treatment options for complicated/severe P. falciparum malaria? [3]
If patient is in shock what does this indicate? [2]
Parasite count >2%
-IV artesunate (unlicensed in UK)
-IV quinine plus oral doxycycline (or clindamycin)
Parasite count >10%: exchange transfusion
Shock may indicate co-existent gram -ve bacterial sepsis (algid malaria) as malaria rarely causes shock
Treatment of P. vivax/ovale/malariae/knowlesi malaria? [3]
- ACT (Artemisin based combination therapy) or
- Chloroquine
- Add primaquine (14d) in vivax and ovale to eradicate liver hypnozoites
What are some malaria control programmes? [4]
- Mosquito breeding sites (draining standing water)
- Larvacides
- Mosquito killing sprays
- Human behaviour (bed nets, mesh windows)
Typhoid fever
2 causes
What organisms cause this? [2]
Incubation period
Typhoid fever is widespread and happens due to poor sanitation and unclean drinking water.
- Salmonella typhi
- Salmonella paratyphi
- 1-4 weeks
What clinical features are seen in the first week of disease onset?
5 generalized flu-like symptoms
3 signs
Generalised flu-like symptoms
- Fever
- Headache
- Abdo discomfort
- Constipation
- Dry cough
- Relative bradycardia
- Neutrophilia
- Confusion
What clinical features are seen in the second week of disease onset? [5]
- Fever
- Rose spots
- Diarrhoea
- Tachycardia
- Neutropenia
What clinical features are seen in the third week of disease onset? (complications arise) [4]
- Intestinal bleeding
- Perforation
- Peritonism
- Metastatic infections
Typhoid fever
What clinical features are seen in the fourth week of disease onset?
Rate of relapse
Usually recovery begins in 4th week of disease onset
10-15% relapse
How do you diagnose typhoid fever? [3]
Clinical dx
Lab
Cultures: blood, stool, urine, bone marrow (Looking for Salmonella typhi/paratyphi)
How do you treat typhoid fever? [3]
- Notifiable disease
- Oral azithromycin 1g
- IV Ceftriaxone (esp if complicated)
Dengue fever is the commonest human arbovirus infection. Ax and transmission? [2]
Dengue arbovirus spread by Aedes aegypti (type of mosquito)
What are the symptoms and signs of classical dengue fever? [5]
Includes one clinical test
What are features of severe dengue? [3]
- Sudden fever
- Sudden headache, retro-orbital pain
- Severe myalgia and arthralgia
- Macular/maculopapular rash
- Haemorrhagic signs: petechiae, purpura, positive tourniquet test
Severe dengue: severe plasma leakage, severe bleeding, organ failure
How is dengue fever diagnosed? [6]
What is the tourniquet test
- Positive tourniquet test
- PCR
- Serology
- FBC (leukopenia, thrombocytopenia)
- LFT (elevated AST and ALT)
- clotting (DIC = prolonged APTT and INR, increased D-dimer, reduced fibrinogen)
Tourniquet test
- This test is performed by inflating a blood pressure cuff on the upper arm to midway between diastolic and systolic blood pressures for 5 minutes. The results are considered to be positive if more than 20 petechiae per square inch are observed on the skin in the area that was under pressure
What is the management of Dengue fever? [3]
What are 2 complications?
Supportive
-Mx: IV fluids, fresh frozen plasma, platelets
Complications
- Dengue haemorrhagic fever
- Dengue shock syndrome
Schistosomiasis is spread via freshwater snails. What are the 3 water born parasites that cause this?
- Schistosomiasis haematobium
- Schistosomiasis mansoni
- Schistosomiasis japonicum
What is the schistosomiasis life cycle? [5]
- Infected snails penetrate human skin while swimming etc
- Circulate in body, lose tails to become schistosomulae in body upon penetration
- Migrate to portal blood in liver/mesenteric venules of bowel/rectum/venous plexus of bladder
- Released in urine/faeces into sea
- Parasite infects snail and cycle continues
The first clinical feature of schistosomiasis is Swimmers Itch, which presents after a few hours and stops after a day or two.
What clinical features occur in the invasive stage? [4]
- Cough
- Abdo discomfort
- Splenomegaly after 24h
- Eosinophilia
What clinical features are seen in the Katayama fever seen in schistosomiasis? [4]
Onset?
- Fever
- Urticaria
- Lymphadenopathy
- Splenomegaly
- After 15-20 days
What happens in acute disease of schistosomiasis? [2] (also get chronic disease)
- S. haematobium: frequency, haematuria and urinary calcification after 6-8w
- S mansoni and S. japonicum: dysentery after 6-8w
How is schistosomiasis diagnosed? [4]
- Clinical diagnosis
- Antibody tests
- Ova in stools and urine
- Rectal snip
What is the treatment for schistosomiasis? [2]
- Praziquantel (2 doses 6hr apart)
- Prednisolone if severe
What are the different types of rickettsiosis diseases and what organism causes them?
- Tick typhus (rickettsia conorii/africae)
- Rocky mountain spotted fever (rickettsia rickettsii)
- Epidemic typhus (rickettsia prowazekii)
- Scrub typhus (rickettsia tsutsugamushi)
What is the most common rickettsiosis disease imported to UK?
Tick typhus (from S Africa, Mediterranean, Arabian Gulf)
What are the clinical features of rickettsiosis? [8]
- Abrupt onset swinging fever
- Headache
- Confusion
- Endovasculitis
- Rash (macular, petechiae)
- Bleeding
- Reactive arthritis, neck myalgia
- Tick bite eschar
What are the investigations for rickettsiosis? [3]
What is the treatment for rickettsiosis?
Ix: serology (IgM or IgG), FBC (leukopenia, thrombocytopenia), U&E and electrolytes (hyponatraemia)
Doxycycline
How is Zika virus transmitted? [3]
- Aedes mosquitoes
- Sexual contact
- Blood transfusion
What are the clinical features of Zika virus? [8]
- none/mild symptoms
- Headache
- Rash
- Fever, malaise
- Conjunctivitis
- Joint pains
- Fetal problems: microcephaly and other neuro problems
- Can cause GBS
What treatment is there for Zika virus? [3]
- No antiviral therapy
- Mosquito control measures
- Vaccines in development
What should be focused on in a patient history in a returning traveller with symptom onset? [6]
o Geographical location: urban/rural, geographical/travelled through o Risk activities: swimming, game park o Trip purpose o Accommodation Sexual hx o Contacts o Vaccines and malaria prophylaxis
Upon examination, what diseases does rash point to? [3]
- Typhoid (salmonella)
- Tick Typhus
- Dengue
Upon examination, what diseases does jaundice point to? [3]
- Hepatitis
- Malaria
- Yellow fever
Upon examination, what diseases does lymphadenopathy point to? [2]
- Leishmania
- Trypanosomiasis
Upon examination, what diseases does liver symptoms point to? [3]
- Malaria
- Typhoid
- Amoebic abscess
Upon examination, what diseases does splenomegaly point to? [3]
- Visceral leishmaniasis
- Typhoid
- Malaria
What general investigations should be done for travel acquired infections? (as well as specific investigations)
- FBC
- Malaria films
- LFTs
- Stool microscopy and culture
- Urine analysis and culture
- Blood culture
- CXR
General treatment for travel acquired infections? [4]
- Isolation: (PPE, single rooms)
- Supportive measures
- Empirical treatment
- Specific treatment once diagnosis established
Name 3 features of cerebral malaria
Name 4 features of blackwater fever
-Cerebral malaria (encephalopathy): convulsions
hypoxia
hypoglycemia
-Blackwater fever: severe haemolysis high parasitaemia acute renal failure haemoglobinuria - black urine
Anti-malaria prophylaxis [4]
Malarone
Chloroquine
Doxycycline
Mefloquine
Anti-malaria prophylaxis: Malarone and Chloroquine
Describe timing, SE, CI
Malarone
- take 1-2d before travel
- SE: GI upset
- CI: pregnancy unless folate supplementation
Chloroquine
- Take 1w before travel
- Retake weekly
- SE: headache
- CI: epilepsy
- suitable in pregnancy
Anti-malaria prophylaxis: Doxycycline and Mefloquine
Describe timing, SE, CI
o DOXYCYCLINE: take 1-2d before travel (SE: photosensitivity, oesophagitis; CI: pregnancy, children)
o MEFLOQUINE: taken 1w before and re-taken weekly (CI: hx depression)
What is dengue shock syndrome [4]
- poor peripheral perfusion
- narrow pulse pressure
- reduced cerebral perfusion
- shock early in disease
Viral hemorrhagic fever
Ax [4]
Pathophysiology [3]
- Ax:
yellow fever, dengue, Ebola (2-21d incubation peroid), Lassa fever
Px:
- viremia attacks vascular system
- leading to increased vascular permeability
- causing haemorrhage, hypotension and shock
Viral hemorrhagic fever
Describe early signs [4], initial signs [6]
What are florid signs of this syndrome? [3]
- early signs: non-specific w/ pyrexia, headache, myalgia and N&V
- initial signs: high fever, oedema conjunctival injection, maculopapular or petechial rash, jaundice and altered mental state
- florid signs are coagulopathy and haemorrhagic cx and multi-system organ failure
Viral hemorrhagic fever - describe what are complications of hemorrhage [3]
Mx [2]
hepatic damage, myocarditis, encephalopathy
- High security infection unit
- Supportive treatment
Yellow fever
Ep [2]
Ax [2]
Incubation period
Ep: Africa and South America
Ax: flavivirus spread by Aedes mosquito
Px: 2-4d incubation period
Yellow fever
Presentation [5]
Ix [3]
- sudden onset high fever, rigors
- N&V
- bradycardia
- brief remission
- followed by jaundice, hematemesis and oliguria
Ix: serology, ELISA, PCR
Yellow fever
Describe what you would see on FBC, LFT, U&E, Cr
Mx [2]
Complication
FBC (leukopenia, thrombocytopenia if coagulopathy)
LFT (elevated AST and ALT)
U&E and creatinine (AKI)
Mx: rehydration therapy, notifiable disease
Cx: viral hemorrhagic fever
Lassa fever Ep Vector Causative organism Describe a mild presentation [2] Describe neurological sequelae [3]
Endemic in West Africa
Vector: multimammate rat
Lassavirus
Presentation
- 1-3w
- Mild symptoms: slight fever, malaise, headache
- neuro: hearing loss, tremors, encephalitis
Describe serious symptoms of Lassa fever [6]
Risk factor [3]
Serious (20%):
- hemorrhage: mucosal bleeding
- conjunctivitis
- respiratory distress
- vomiting
- facial swelling
- chest pain, back, abdomen
- shock
Risk factors:
- Endemic areas
- HCW
- Butchering or eating rodent meat
Lassa fever investigations [4]
Treatment
- RT-PCR
- Serology
- rapid diagnostic lateral flow assay
- Check for typhoid & malaria (usually co-endemic and as differential)
Mx:
- Ribavirin IV
