Lecture 9.1 - Travel related infections.pdf

Considerations: ◦Factors to consider in travel related infections ‣ Country/countries visited ‣ Accommodations/activities ‣ Food/water ◦Important travel related infection and pathogens ◦Prevention measures International travel (Pre-SARS-CoV-2):...

Considerations: ◦Factors to consider in travel related infections ‣ Country/countries visited ‣ Accommodations/activities ‣ Food/water ◦Important travel related infection and pathogens ◦Prevention measures International travel (Pre-SARS-CoV-2): ◦International travel increased by 50% over the past decade ◦Long-distance travel, especially to Asia and Africa, has increased ◦Travel frequency increasing for people with comorbid conditions, those travelling for business, or those visiting friends and relatives ‣ E.g. people who are immunocompromised Travel related illness: ◦Travel-related health problems have been reported in as many as 22-64% of travellers to developing countries ◦Although most of these illnesses are mild, up to 8% of travellers are ill enough to seek care from a health care provider ◦Most post-travel infections become apparent soon after travel, but incubation periods vary, and some syndromes can present months to years after initial infection ‣ For example, some forms of malaria can remain dormant in he body, but activate years after infection ◦The 3 most common presenting c/o - fever, diarrhoea and rash Travel location(s) and duration of stay: ◦The longer the stay in a developing country the greater the risk of travel related illness ◦Short stays are considered < 2-3 weeks ◦Long stays are > 1 month ◦The destination may include or exclude certain illness that follow geographic patterns and seasons Evaluation of travel related illness: ◦Travel itinerary and duration of travel (destinations and seasons) ◦Exposure history (accommodation, food, activities, sexual partners) ◦Timing of onset of illness in relation to international travel (incubation period) ◦Severity of illness ◦Past medical history and medications ‣ General health and immune status ◦History of a pre-travel consultation ‣ Travel immunisations ‣ Adherence to malaria chemoprophylaxis Source of infection: ◦Type of accommodations ◦Insect precautions taken (such as repellent, bed nets) ◦Source of drinking water ◦Ingestion of raw meat or seafood or unpasteurised dairy products  ◦Insect or arthropod bites ◦Freshwater exposure (such as swimming, rafting) ◦Animal bites and scratches ◦Body fluid exposure (such as tattoos, sexual activity) ◦Medical care while overseas (such as injections, transfusions) Precautions: ◦Important to understand danger of infection to others ‣ PPE (cost of equipment) ‣ Isolation ‣ Care when handling samples for laboratory ‣ Taking appropriate history ‣ Appropriate diagnostic tests ‣ Supportive and specific treatment Accommodation and travel: ◦Crowded living conditions, group travel, exposure to ill persons: ‣ Meningococcal disease ‣ Influenza, MERS-CoV, SARS-CoV ‣ Tuberculosis ‣ Viral Haemorrhagic fever (VHF) - virus causes a reduction in platelets, leading to bleeding all over: Lassa (rats), Marburg (fruit bats), Ebola (fruit bats) ‣ Hepatitis A Exposure - Arthropods: ◦Mosquitoes ‣ Malaria (protozoa) ‣ Dengue (virus) - causes haemorrhagic disease ‣ Yellow fever (virus) ‣ Japanese Encephalitis virus ‣ West Nile virus ‣ Rift valley fever (virus): Sub-Saharan Africa ‣ Chikungunya (virus) ‣ Others Incubation period causes GI problems ◦East African trypanosomiasis  Incubation period >21 days: ◦Malaria (especially after ineffective prophylaxis) ◦Acute HIV ◦Acute systemic Schistosomiasis (Katayama fever) ◦Viral hepatitis (A, B, C, D and E) ◦Tuberculosis ◦Leishmaniasis ◦West African trypanosomiasis Characteristic findings: ◦Physical: ‣ Vital signs ‣ Skin findings including bite marks (insect bites) ‣ Joint, respiratory, gastrointestinal, neurological ◦Laboratory/diagnostic investigations: ‣ Eosinophilia (higher than normal level or eosinophils - parasitic infection) ‣ Leukopenia (low white blood cell count) ‣ Thrombocytopenia (low blood platelet count) -> leads to viral haemorrhagic fever ‣ LFTs ‣ Identification of organism (culture, PCR) ‣ Identification of immune response ‣ Chest X-ray (check for TB) ‣ CT scan (check for abscesses or problems in an organ) Illnesses associated with fever presenting in the first 2 weeks after travel: ◦Systemic febrile illness with initial non-specific symptoms: ‣ Malaria ‣ Dengue ‣ Typhoid fever ‣ Rickettsial diseases (such as scrub typhus, spotted fevers) ‣ East African trypanosomiasis ‣ Acute HIV infection ‣ Leptospirosis ‣ Ebola virus disease ‣ Viral hemorrhagic fevers ◦Fever with central nervous system: ‣ Meningococcal meningitis ‣ Malaria ‣ Arboviral encephalitis (such as Japanese encephalitis virus, West Nile virus) ‣ East African trypanosomiasis ‣ Rabies ◦Fever with respiratory symptoms ‣ Influenza ‣ Bacterial pneumonia  ‣ Legionella pneumonia ‣ Q fever ‣ Malaria ‣ Pneumonic plague ‣ Middle East respiratory syndrome (MERS) ◦Fever and skin rash: ‣ Dengue ‣ Chikungunya ‣ Zika ‣ Measles ‣ Varicella ‣ Spotted fever or typhus group rickettsiosis ‣ Typhoid fever ‣ Acute HIV infection Exposure - food and water: ◦Hepatitis A ◦Enteric fever (typhoid paratyphoid) ◦Bacterial gastroenteritis - traveller's diarrhoea usually caused by E.Coli ◦Amoebiasis Hepatitis A: ◦Spread by faecal-oral route (shellfish which are harvested from contaminated water) ◦Symptoms: ‣ Feeling tired and generally unwell ‣ Joint and muscle pain ‣ A raised temperature ‣ Loss of appetite ‣ Feeling or being sick ‣ Pain in the upper right part of the tummy ‣ A raised, itchy rash ‣ Diarrhoea/constipation ◦Vaccine available Travellers diarrhoea: ◦Enterotoxigenic strains of Escherichia coli (ETEC) ‣ Gram negative bacilli ‣ O - cell wall antigen ‣ H - antigen on flagella ‣ K - antigen in the polysaccharide capsule ◦Other types of E.coli are: ‣ Enteropathogenic (EPEC) - watery diarrhoea over long period; infants in developing countries ‣ Enterohaemorrhagic (EHEC) - bloody diarrhoea ‣ Enteroinvasive (EIEC) - bloody diarrhoea  ‣ Enteroaggregative (EAEC) - persistent diarrhoea in HIV positive children and adults E.coli: ◦Symptoms: diarrhoea, stomach cramps and occasionally fever. About half of people with the infection will have bloody diarrhoea ◦Supportive treatment - hydration, antipyretics to reduce fever ◦Antibiotics - typically given to people who are immunocompromised Exposure - unpasteurised dairy products: ◦Brucella species (dogs, goats, cattle, camel) ◦Salmonella gastroenteritis ◦Tuberculosis (M bovis) Dairy - Brucella species: ◦Gram negative coccobacilli ‣ Recurrent, prolonged episodes of fever ‣ Worse at night ‣ Associated with sweating ‣ May have focal area of pain or generalised illness ‣ Infection from ingesting dairy products ◦Diagnosis: blood culture, PCR ◦Treatment - antibiotics Water - enteric fever: ◦Caused by salmonella typhi or S. paratyphi ‣ Gram-negative bacilli ◦High fever, chills, headaches, anorexia, weakness, diarrhoea or constipation ◦Diagnosis: ‣ Stool culture ‣ Bone marrow aspirate ‣ The white blood cell (WBC) count is often low Vaccines to prevent Salmonella infections: ◦A polysaccharide vaccine based on the purified Vi-antigen (Vi-PS vaccine) ‣ This single-dose intramuscular or subcutaneous injectable ‣ Protective efficacy 70% ◦A life attenuated oral vaccine (Ty21a, made with attenuated S. typhi strain Ty2) ‣ Available in capsules ‣ Protective efficacy of 33-67% Malaria: ◦5 main species of Plasmodium: ‣ Falciparum ‣ Vivax ‣ Ovale  ‣ Malariae ‣ Knowlesii ◦Vector - female anopheles mosquito ◦250 million cases and 1 million deaths each year ◦Commonest imported infection to UK ◦~1500 cases per year ‣ Up to 11 deaths/year ‣ 75% falciparum (90% cases from Africa, mortality 10-20%) ‣ Remainder mostly vivax/ovale (90% cases from India) Lifecycle of malaria: ◦Mosquito transfers sporozoites in its saliva into blood of humans ◦Sporozoites migrate to the liver and mature into schizonts which rupture and release merozoites. Merozoites are released and infect red blood cells ◦Merozoites reproduce asexually in the red blood cells - first stage get an early ring form, called the early trophozoite which grows to the late trophozoite stage ◦Some merozoites enter the sexual cycle to produce gametocytes (male and female) which remain in the red blood cells ◦Gametocytes are taken up by mosquitoes when they feed on people. The male and female gametocytes give rise to zygotes in the mosquito gut which develop into ookinete and finally oocysts which rupture releasing the sporozoites Clinical features of malaria: ◦Patients asymptomatic from time of the original mosquito bite until approx a week later ◦Typical incubation period usually between 8-17 days for P. falciparum, P vivax and P ovale and 18-40 days fro P malariae ◦Initial symptoms of malaria are non-specific and similar to the symptoms of a minor systemic viral illness ‣ Fever, headache, fatigue, muscle and joint pain, nausea and vomiting Investigations and treatment: ◦Blood film x3 ◦FBS, U&Es, LFTs ◦Head CT scan if neurological symptoms ◦Treatment depends on species: ‣ P. falciparum: Artesunate Quinine + doxycycline ‣ P. vivax, ovale, malariae: Chloroquine with primaquine ◦Dormant hypnozoites (liver) ‣ Can recur months - years later ‣ Give additional primaquine  Blood film: ◦This Giemsa-stained, blood film showing Plasmodium falciparum ring-forms, and gametocytes Severe malaria: ◦Clinical features: ‣ Impaired consciousness/coma ‣ Prostration or sit up with assistance ‣ Convulsions ‣ Deep breathing, respiratory distress (acidotic breathing) ‣ Circulatory collapse/shock, systolic blood pressure 39 oC, chills ‣ Later invasion of liver, kidneys and CNS ‣ Gives rise to jaundice, hemorrhage, tissue necrosis ‣ Aseptic meningitis (inflammation of meninges without positive culture) Exposure - new sexual partners: ◦HIV ◦Hepatitis B ◦Other STDs - herpes, gonorrhoea, syphilis, HPV Travel related vaccinations: ◦Yellow fever - Africa, South America, Central America and Trinidad in the Caribbean ◦Hepatitis A - low to middle income countries ◦Typhoid - Asia, Africa, Latin America, the Caribbean and Oceania, but 80% of cases come from Bangladesh, China, India, Indonesia, Laos, Nepal, Pakistan or Vietnam ◦Meningitis - Saudi Arabia (hajj) ◦Japanese encephalitis - South East Asia and Western Pacific ◦Rabies - Asia and Africa