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Travel Vaccines & Yellow Fever
By: CHARLES N. CHUNGE MB ChB MSc, CNM, PhD, MSc, DLSHTM, FRCPS(Glasg)
Consultant Microbiologist, & Specialist in Tropical & Travel Medicine.
Director of the Centre for Tropical &Travel Medicine – Nairobi, Kenya.
MAIN OBJECTIVE TODAY
To make you medical people aware that excellent vaccines are available to prevent many serious/deadly diseases, so that you will take appropriate action to protect yourself & others.
What your objectives should not be!!
• To sleep here (This is not Parliament)
• To get to the TEA BREAK area very fast before others.
• To stare at other guests• To ask political questions• To sit next to her/him
A TRAVELLER IS A PERSON WHO:(Yes/No)
GOES ON SAFARI IS A TOURIST EATS IN A RESTAURANT OR
HOTEL TRAVELS OVERSEAS CATCHES A BUS, AEROPLANE,
TRAIN etc? INGESTS FOOD PREPARED
OUTSIDE HIS HOME
Which are the common diseases that afflict travellers?• Yellow Fever• AIDS?• Cholera• Travellers Diarrhoea• Hepatitis A• Hepatitis B• Influenza = Flu• Japanese encephalitis• Malaria?• Measles/Mumps/Rubella*
• Meningitis• Pneumonia• Rabies• Diphtheria• Tetanus• Polio• Tuberculosis• Typhoid fever• Cancer of CERVIX• Food-poisoning
As you can see from this list of diseases:
• Many of these diseases can be prevented by vaccines.
• Many cannot be cured easily.
• With the increase in travel, serious diseases are literally only a plane-ride away.
Vulnerable groups• Infants, because their immune systems cannot
easily fight off disease.• Children & workers in crowded situations• The Immuno-depressed/compromised• Those pregnant • Malnourished individuals• Old people (? Over 65yrs)• Professional groups (medical, military, students,
nurseries, orphanages, prisoners)• All Travellers
CHRONIC CONDITIONS WORSENED BY FAILURE TO VACCINATE
• HEART DISEASES• LUNG DISEASES• LIVER DISEASES• KIDNEY DISEASES• MENTAL DISEASES - ? Where? Kisii?• JOINT DISEASES• DIABETES, HIV, etc
Available Vaccines for travellers• Yellow Fever – Mandatory• Meningitis – sometimes mandatory (during Hajj)• Diphtheria-Tetanus (dT)• Typhoid, Travellers diarrh, Cholera,• Hepatitis A• Hepatitis B• Rabies• Polio• Measles-Mumps-Rubella• Influenza• Pneumococcal• Japanese encephalitis• Human Papilloma Virus (Cervical cancer)• Tuberculosis*** Malaria****HIV****
TRAVEL VACCINES: Classification Divided into 3 categories:• Mandatory (M): International Certificate required
– Yellow fever vaccine• Recommended (R) for all travellers to certain
countries– Meningo ACYW135 (Saudia Arabia) for Hajj
travellers– dTPolio to North and South America
• Recommended (r) for travellers to certain areas– Influenza and Pneumococcal vaccines for at
risk subjects: >65 yrs– Varicella for travellers to USA who do not
have antibodies– Rabies in Latin America
Vaccines for healthcare workers
• Hepatitis B • Influenza vaccine (annually for the flu) • Measles-Mumps-Rubella (MMR) vaccine
• Varicella (chickenpox) vaccine • Typhoid• Meningitis
Vaccines for StudentsRecommended or Mandatory (depending on
who?) dT-Polio (diphtheriaTetanusPolio) Pneumococcal, Flu, Meningitis Hepatitis A Hepatitis B Measles,mumps,Rubella(MMR)-Susceptible/
without antibodies Varicella (chicken pox) Typhoid ETEC travellers diarrhoea & Cholera
There are no vaccines for:
Malaria (current efficacy =35-45%)
HIV (current efficacy <31%) Rift Valley Fever Bird Flu = Avian influenza Gonorrhoea or Syphilis Swine Flu H1N1 – remarkable efforts Anthrax Most STIs
The Value of Vaccination
Produces two Types of Protection OR Immunity among clients:
-Individual immunity
-Community Immunity
(Herd Immunity) !
Impact of vaccination: Benefits1. Immunisation saves 3Million lives/year
(WHO)2. Immunisation is second to provision
of clean water and third are antibiotics in saving lives
3. In addition to preventing disease, it reduces mortality, morbidity and medical/travel costs
4. It costs less than treatment5. It is easily explained
Vaccination costs less than treatment (this is excellent for a traveller)
For example typhoid:
Vaccine Ksh 500-1000 every 3 years
Treatment of disease Ksh >12000 twice a year?
Man hrs lost on off duties
School HRS lost on absenteeism
Cost of death = is too large to calculate
The Wise choice• Choosing to avoid vaccines is simply a choice
to take a different risk – usually much worse: =>the disease & its complications.
e.g. meningitis, pneumonia, Yellow fever, paralysis, deafness caused by mumps, liver cancer (by hepatitis B virus), heart failure, kidney failure, peritonitis (typhoid) and of course DEATH.
Therefore: When you compare the side effects/benefits of vaccines and the risk of the actual diseases, vaccines are the safer choice."
WHICH DOCTORS ARE LIKELY TO ADVISE PATIENTS ON PREVENTIVE MEASURES?
• PAEDIATRICIANS&Travel Medicine Specialists
• PUBLIC HEALTH SPECIALISTS• GYNAECOLOGISTS• PHYSICIANS & General Practitioners• DERMATOLOGISTS• SURGEONSWhy these differences?
Who consults prior to travel? (In descending order)
»AMERICANS»JAPANESE= very nice people
»GERMANS & FRENCH»SCANDINAVIANS»OTHER EUROPEANS»THE BRITISH »INDIANS,CHINESE
RUSSIANS, AFRICANS etc
What about Kenyans?
• Kenyan people and medical insurance companies want to treat the illnesses once it occurs; they tend to react only when a crisis occurs.
• They always try to skip mandatory vaccines (even doctors!)
• We need to teach them the truth: “Prevention is better than cure”
Yellow Fever• Why the name?• The arbovirus is called Flavivirus • The vector: Aedes, Haemagogus
mosquitoes
• Prevalence = Variable (Africa & Americas)
• India & Asia/Far East = Nil (but very
suitable) • A zoonosis = Primates reservoirs
Yellow Fever• Endemic areas: Africa and C.&S.
America• Urban YF seen in South America• Sub clinical cases may occur = 15%• Kills over 60-80% of its victims • Why is it the only compulsory
vaccine?Because: The vectors, the primates & humans exist in Asia
But the disease does not.
JUNGLE TYPE YELLOW FEVER• This enzootic cycle is essentially animal and
keeps the virus alive in the tropical forest of Africa and South America
• In Africa, Monkeys do not die once infected, they become and remain immune.
• Monkeys don’t act as virus hosts, as their viremia is short but rather as amplifiers & indicators of virus circulation
• Transovarial transmission in the mosquito keeps the virus alive
DIAGNOSIS / TREATMENT• Incubation period: lasts 3 to 6 days• Evolution :
-Acute forms are fatal in 2-7 days,
-Severe forms are fatal > 80% of cases.
-Milder forms similar to flu-like syndrome or viral hepatitis.
Mortality: Upto 80 % despite treatment
Diagnosis: Serology
Yellow Fever: TREATMENT• There is no specific anti-viral Yellow fever
therapy
• The mortality rate for acute forms of the disease is 80%, despite any treatment
• The only efficient prevention is the routine vaccination of all persons exposed to the disease risk
• Vaccination for international travellers is aimed at preventing travellers from getting infected abroad and taking the disease back home.
Side effects: Viscerotropic and Neurotropic Disease
Age >60 years •Risk of Viscerotropic Disease:
≈ 20/106 or 1/50,000• Risk of Neurotropic Disease:
≈ 15/106 or 1/65,000
VACCINE EXEMPTIONS allowed: ESPECIALLY IN THOSE >65YRS
Where to go for the vaccination
Vaccination Centres Travel Health clinics Hospitals Medical Clinics (with enlightened
providers)
? Pharmacies Airports/entry/exit points