Session 9: Travel Related Infections Flashcards
Why is travel history so important?
Because the are numerous of disease which could manifest as common diseases from your country. Tropic disease might not be common in the UK but if a person has spent time abroad it will be worth noting. So it is for recognising imported diseases There are different strains of pathogens making them antigenically different. It has impact on protection and detection and on antibiotic resistance. You also need to be wary of the infection in the hospital to not spread it on ward between staff or other patients. Also need to list it as suspected travel disease when sending to lab to not infect them.
Four important questions to ask when it comes to travel related infections.
Where have they been? When did the symptoms arise/When were they there? What are the symptoms? How did they acquire it?
Three most common places to get travel related diseases.
Sub-saharan africa South-east Asia South and Central America
Classification of time between onset till seeking medical attention.
<10 days is acute 10-21 days is subacute >21 days is chronic
Give common symptoms and signs of travel related disease.
Resp GI like diarrhoea Skin rash Jaundice CNS like headache and meningism Haematological like lymphadenopathy, splenomegaly or haemorrhage. Eosinophilia
Give examples of mode of acquisition of travel related disease.
Food/water Insect/tick bite Swimming Sexual contact Animal contact Recreational activities (drugs)
Give 1-2 common infections/microbes of each: 1. Animal bite 2. Rodents 3. Mosquito/insect bite 4. Tick bite 5. Dead/slaughtered animals 6. Farms 7. Game parks 8. Fresh water 9. Caves 10. Unpasteurised dairy 11. Shellfish 12. Under/uncooked fish/meat
1 - Rabies 2 - leptospirosis via rodent urine 3 - Malaria or dengue 4 - Rickettsia 5 - Anthrax 6 - Q-fever 7 - Rickettsia 8 - Schistosomiasis or leptospirosis 9 - Histoplasmosis 10 - Brucellosis 11 - Viral hepatitis A and E 12 - Salmonella
Other important questions to ask of travel history.
Any unwell travel companions or contact. Pre-travel vaccinations or preventative measures. Healthcare exposure
Man comes in with fever. Low BP, high HR and low Sat.
Slightly unwell and confused.
Multiple bite marks and hepatosplenomegaly with moderate icterus.
Hb is low, WCC is low and platelets are low.
Urea is high, creatinine high, bilirubin high but ALT and ALP are both normal.
CRP is high.
Comment on the anaemia. What is the most likely cause of the anaemia?
The haemoglobin is low.
However bilirubin is high which suggests that there is no problem in producing red blood cells. The low haemoglobin and raised bilirubin suggests that there is an increased destruction of RBCs. This is most likely due to some defect of the RBC. Because of the bites it is likely that something has gotten into the red blood cells making them get destroyed. Splenomegaly suggests that there is increased breakdown of RBCs.
Blood film is done. Most likely diagnosis.
Parasites in RBCs. Most likely malaria.
5 main species of Malaria.
Which are most common?
Plasmodium falciparum (most common)
Plasmodium vivax (second to most)
Plasmodium ovale
Plasmodium malariae
Plasmodium knowlesii
Vector of malaria.
Female Anopheles mosquito
Common places for contraction of malaria.
Subsaharan Africa
Southeast asia
Central and south america
Incubation period of malaria.
A minimum of 6 days.
In Plasmodium falciparum by 4 weeks
In Plasmodium vivax and ovale up to 1 year+
Symptom history of malaria.
Fever chills and sweats cycle every 3rd of 4th day.
Symptoms of malaria (can be ambiguous and vary).
Headache
Fever
Muscular fatigue and pain
Back pain
Chills and sweating
Respiratory with dry cough
Splenomegaly
Nausea
Vomiting
Upon examination. What are you likely to find suspecting malaria.
Often few signs except fever and sometimes splenomegaly
Symptoms of severe falciparum malaria.
Cardiovascular like tachycardia, hypotension and arrhythmias
Respiratory like acute respiratory distress syndrome
GI tract like diarrhoea, deranged LFTs and bilirubin
Renal with acute kidney injury which can be seen in increased Urea
CNS with confusion and fits
Blood: normal to low WCC, thrombocytopenia and DIC
Metabolic: Metabolic acidosis and hypoglycaemia
Secondary infection
Investigation of malaria.
Blood film x3
FBC
U&E
LFTs
Glucose
Coagulation
Head CT scan
Chest x ray
Treatment of malaria.
Depends on the species.
Plasmodium falciparum:
Artenusate or Quinine + doxycycline
Do not give chloroquine to falciparum
Plasmodium vivax, ovale and malariae:
Chloroquine
Primaquine
You’ve had treatment for malaria which turned out to be Plasmodium vivax. Why might you get malaria symptoms years later again?
Because the hypnozoites may lay dormant in the liver for many years before starting to reactivate again. This means that you will get malaria again as the hypnozoites begins to reproduce and is eventually released into blood stream again
Well in blood cell they reproduce and will reproduce until the RBC bursts.
Prevention of malaria (mnemonic)
ABC
Assess risk (where do you travel)
Bite prevention - repellants and adequate clothing and nets
Chemoprophylaxis which will be specific to the region. So you start the prophylaxis before travel and contine after return for about 4 weeks.
35 year old asian female.
Returned from india 18 days ago
Family visit whilst away
5/7 abdo cramps, loose motions and constipation. Dry cough and head ache.
Pyrexic 39 degrees, Hr 80, Bp 105/65, with a clear chest
Abdomen is generalised tenderness and spleen tip is tender with a faint pink rash.
Wcc is 2.9, neutrophils is at 1.5 and lymphs at 1.1.
U&E is normal
ALT is 155 so SE and ALP is 180 so SE with CRP at 250.
Chest xray is normal and so is abdominal xray.
Some mild splenomegaly.
Diagnosis.
India.
Abdo cramps and constipation
Splenomegaly and low counts with somewhat affected liver with a high CRP. High enough CRP to be infection.
Salmonella typhi
What does Salmonella typhi cause?
It causes typhoid and paratyphoid fever which are both examples of enteric fever.
Description of typhoid and paratyphoid fever.
(Region affected)
(Why it is affected)
Mechanism of infection
Mainly asia due to poor sanitation but can also be africa or South america.
Faecal-oral from contaminated water and food.
Source is cases or carriers.
Organisms causing typhoid and paratyphoid fever.
Brief description of them
Salmonella typhi
Salmonella paratyphi A,B or C
They are Enterobacteriaceae: aerobic Gram-negative bacillus
Virulence factor of paratyphoid and typhoid fever.
Low infectious dose
Survives gastric acid
Fimbriae adhere to epithelium over ileal lymphoid tissue which are the Peyer’s patches. This goes into RE system and blood.
They reside within macrophages liver/spleen/bone marrow
Symptoms and signs of enteric fever.
+ incubation
Systemic disease so would cause bacteraemia/sepsis
Incubation is 7-14 days
Fever, headach, abdo discomfort and dry cough
Relative bradycardia
Complications of enteric fever?
Intestinal haemorrhage and perforation; seeding
10% mortality if untreated
Chronic carrier in about 1-5%
Which one is milder, paratyphoid or typhoid fever?
Paratyphoid fever
Investigations of enteric fever.
Moderate anaemia
Lymphopaenia
Raised LFTs like transaminase and bilirubin
Blood culture which will be positive in 40-80% of cases
Faeces + bone marrow culture
Serology for antibody detection although not very reliable
Enteric fever - Treatment.
They are multi-drug resistant unfortunately including against penicillins so fluoroquinolones like ciprofloxacin can work but that is increasing in resistance.
It is usually treated with IV ceftriaxone which is a cephalosporin or with azithromycin which is a macrolide for 7-14 days.
Enteric fever prevention.
Food and water hygiene precautions
Typhoid vaccine in high risk travel or for laboratory personnel
Capsular polysaccharide antigen or live attenuated vaccine
Modest protective effect however in vaccine at around 50-75%
What are non-typhoidal salmonella infections?
Give example of microbes
Symptoms and signs
Severity
These are the food-poisoning salmonellas
It is widespread in UK
S. typhimurium and S. enteritidis
Diarrhoea, fever, vomiting, abdo pain
Usually self-limiting but bacteraemia and deep-seated infections may occur
26 yo British male
Travel to cambodia 1 1/2
Returned 2/7 ago with abrupt fever, back pain and head ache behind eyes
Pyrexic at 39.5 degrees, HR is 110, BP 110/85
Hb 139, WCC 3.8, Lymph at 1.0, Plt at 100
ALT is raised at 75
Presenting with a fever and a rash that is all over the body very spotty.
Differential diagnosis
Childhood viruses like MMR
Infectious mononucleosis (EBV / CMV)
Acute HIV infection
Rickettsia (Spotted fever)
What are the following investigations to do?
Blood culture
Malaria screening
Stool and urine culture
CXR and AXR and head CT
Dengue PCR
Dengue serology (IgM)
Blood culture is negative
Malaria screen is negative
Stool and urine negative
CXR, AXR and CT head are all normal
Dengue PCR is positive and so it Dengue serology (IgM)
Diagnosis?
Dengue fever
Microbe
Amount of serotypes
Regions
Transmission
of Dengue Fever
Arbovirus
4 serotypes
Sub and tropical regions like Africa, Asia and Indian SC
Mosquito vector
Describe the pattern of disease of Dengue fever when you acquire it a first time.
First infection ranges from asymptomatic to non-specific febrile illness.
It lasts for about 1-5 days and improves 3-4 days after the rash with only supportive treatment.
What happens if you get infected again with Dengue fever of another serotype?
This is much worse because it is antibody dependent enhancement.
It can cause Dengue haemorrhagic fever in children and hyper-endemic areas
It can also cause Dengue shock syndrome
45 yo caucasian female visiting family in Benin
Rural environment
Multiple bites and spots on back with something falling out of one spot
No other symptoms and no fever
Normal blood tests.
Likely diagnosis?
Myiasis which is a fly larva of tumbu or bot fly.
Ebola
Microbe
Symptoms
Transmission
Filovirus with flu-like symptoms with vomiting, diarrhoea, headaches, confusion and rash
Internal/external bleeding at 5-7 days
Spread by direct contact with body fluids
Zika virus
Microbe
Transmission
Region
Symptoms
Consequences
Arbovirus (flavivirus)
Mosquito vector or sexual transmission
20% get symptoms mild and dengue-like
Congenital microcephaly or foetal loss in affected pregnant women
