Cholera is a bacterial infection transmitted by contaminated food and water. Cholera can cause severe watery diarrhoea although mild infections are common. Most travellers are at low risk.

Prevention
All travellers should take care with personal, food and water hygiene.

Cholera vaccination
This oral vaccine is recommended for those whose activities or medical history put them at increased risk. This includes:

• aid workers.
• those going to areas of cholera outbreaks who have limited access to safe water and medical care.
• those for whom vaccination is considered potentially beneficial.

Hepatitis B is a viral infection; it is transmitted by exposure to infected blood or body fluids. This mostly occurs during sexual contact or as a result of blood-to-blood contact (for example from contaminated equipment during medical and dental procedures, tattooing or body piercing procedures, and sharing of intravenous needles). Mothers with the virus can also transmit the infection to their baby during childbirth.

Hepatitis B in Vietnam
2% or more of the population are known or thought to be persistently infected with the hepatitis B virus (intermediate/high prevalence).

Prevention
Travellers should avoid contact with blood or body fluids. This includes:

• avoiding unprotected sexual intercourse.
• avoiding tattooing, piercing, public shaving, and acupuncture (unless sterile equipment is used).
• not sharing needles or other injection equipment.
• following universal precautions if working in a medical/dental/high risk setting.

A sterile medical equipment kit may be helpful when travelling to resource poor areas.

Hepatitis B vaccination
Vaccination could be considered for all travellers, and is recommended for those whose activities or medical history put them at increased risk including:

• those who may have unprotected sex.
• those who may be exposed to contaminated needles through injecting drug use.
• those who may be exposed to blood or body fluids through their work (e.g. health workers).
• those who may be exposed to contaminated needles as a result of having medical or dental care e.g. those with pre-existing medical conditions and those travelling for medical care abroad including
• those intending to receive renal dialysis overseas.
• long-stay travellers.
• those who are participating in contact sports.
• families adopting children from this country.

Japanese encephalitis (JE) is a viral infection transmitted to humans by the bite of an infected mosquito. These mosquitoes usually bite between dusk and dawn, mainly in rural areas; especially where there are rice fields, swamps and marshes. Mosquitoes become infected by biting JE infected animals (particularly pigs) or birds.

Travellers are at increased risk of infection when visiting rural areas. Short trips (usually less than a month) especially if only travelling to urban areas, are considered lower risk.

Japanese encephalitis in Vietnam
JE occurs in this country, with year-round transmission in the south and from May to October in the north. Cases may be reported outside these months in the north of the country.

Prevention
All travellers should avoid mosquito bites particularly between dusk and dawn.

Japanese encephalitis vaccination
Vaccination is recommended for those whose activities put them at increased risk (see above).

Vaccination could be considered for those on shorter trips if the risk is considered to be sufficient e.g. those spending time in areas where the mosquito breeds such as rice fields, marshlands, or pig farming areas.

Rabies is a viral infection which is usually transmitted following contact with the saliva of an infected animal most often via a bite, scratch or lick to an open wound or mucous membrane (such as on the eye, nose or mouth). Although many different animals can transmit the virus, most cases follow a bite or scratch from an infected dog. In some parts of the world, bats are an important source of infection.

Rabies symptoms can take some time to develop, but when they do, the condition is almost always fatal.

The risk of exposure is increased by certain activities and length of stay (see below). Children are at increased risk as they are less likely to avoid contact with animals and to report a bite, scratch or lick.

Rabies in Vietnam
Rabies is considered a risk and has been reported in domestic animals in this country. Bats may also carry rabies-like viruses.

Prevention
Travellers should avoid contact with all animals. Rabies is preventable with prompt post-exposure treatment.
Following a possible exposure, wounds should be thoroughly cleansed and an urgent local medical assessment sought, even if the wound appears trivial.
Post-exposure treatment and advice should be in accordance with national guidelines.

Rabies vaccination
A full course of pre-exposure vaccines simplifies and shortens the course of post-exposure treatment and removes the need for rabies immunoglobulin which is in short supply world-wide.

Pre-exposure vaccinations are recommended for travellers whose activities put them at increased risk including:

• those at risk due to their work (e.g. laboratory staff working with the virus,
• those working with animals or health workers who may be caring for infected patients).
• those travelling to areas where access to post-exposure treatment and medical care is limited.
• those planning higher risk activities such as running or cycling.
• long-stay travellers (more than one month).

TB is a bacterial infection transmitted most commonly by inhaling respiratory droplets from an infectious person. This is usually following prolonged or frequent close contact.

Tuberculosis in Vietnam
The average annual incidence of TB is greater than or equal to 40 cases per 100,000 population.

Prevention
Travellers should avoid close contact with individuals known to have infectious pulmonary (lung) TB.

Those at risk during their work (such as healthcare workers) should take appropriate infection control precautions.

Tuberculosis (BCG) vaccination
According to current national guidance, BCG vaccine should be recommended for those at increased risk of developing severe disease and/or of exposure to TB infection e.g. when the average annual incidence of TB is greater than or equal to 40 cases per 100,000 population. See Public Health England’s Immunisation against infectious disease, the ‘Green Book’.

For travellers, BCG vaccine is also recommended for:

• unvaccinated, children under 16 years of age, who are going to live for more than 3 months in this country. A tuberculin skin test is required prior to vaccination for all children from 6 years of age and may be recommended for some younger children.
• unvaccinated, tuberculin skin test negative individuals at risk due to their work such as healthcare or laboratory workers who have direct contact with TB patients or potentially infectious clinical material and vets and abattoir workers who handle animal material, which could be infected with TB.

There are specific contraindications associated with the BCG vaccine and health professionals must be trained to administer this vaccine intradermally (just under the top layer of skin).

Following administration, no further vaccines should be administered in the same limb for 3 months.

The BCG vaccine is given once only, booster doses are not recommended.