With 2.2 million deaths a year caused by animal-to-human transmitted diseases, you need to be wary of wildlife, says Dr Jane Wilson-Howarth
A new report, commissioned by the Department of International Development, has just examined the extent of zoonotic diseases – infections that pass from livestock or wild animals to humans.
Disease patterns can be erratic and unpredictable, and the majority of infections are ‘gifts’ from other people. However, when disease-causing microbes are passed from an animal to a human, the human is unlikely to have any kind of immunological experience of the disease and may become seriously ill.
Some of us are immune to the microbes that we meet via animals. A good example of this is toxoplasmosis, a disease that is often transmitted to sheep farmers or cat owners, and generally only causes trouble if first acquired in pregnancy.
However, others are more problematic. Rabies, for instance, is disastrous for both the human victim and the animal responsible. Also, zoonoses seem to have a particular talent for causing terrifying outbreaks of supposedly new diseases: the mixing of animal and human microbes can allow genetic shifts that cause physiological havoc – just witness the bird- and swine-flu outbreaks. It is wise to check for outbreak information before any travel: visit www.fitfortravel.nhs.uk, www.nathnac.org and www.cdc.gov/travel.
The report found that 13 zoonoses are responsible for 2.2 million human deaths every year; many of these are diseases of the poor and debilitated. However, of these 13, eight not uncommonly threaten travellers too: some often make travellers ill; others are rare but, if contracted, horrific.
What is it? Diarrhoea, vomiting and the quease – caused by various microbes. Salmonella causes explosive painful diarrhoea for around ten days; giardia induces foul gaseous emissions for many weeks.
Where do you find it? Anywhere animals roam into food preparation areas, or where dogs are allowed to lick plates.
The lowdown: Oh so common – but well-informed travellers don’t need to suffer.
What you can do: Ensure all food you eat is piping hot. Travel with a thermos of hot water, which will allow you to scald plates, cutlery and cups before use. Take only pasteurised milk products.
What is it? One of those nasty diseases with rather non-specific symptoms, including fever, aches and fatigue; can lead on to jaundice and make people very ill.
Where do you find it? Anywhere there are rats and water.
The lowdown: There have been outbreaks among adventure travellers.
What you can do: Wear protective clothes when doing extreme watersports or caving. Dress and sterilise any scrapes. Keep your mouth closed if you fall in a river!
What is it? Pork tapeworm cysts set up in human tissue; if they settle in the brain they can cause fits and other neurological complications
Where do you find it? Anywhere that pigs can scavenge unsanitary material including human excrement.
The lowdown: Not common but disastrous when it strikes.
What you can do: Ensure any pork is thoroughly cooked – or avoid pork in less sanitary environments. Choose thoroughly cooked foods.
What is it? Viral encephalitis acquired via an animal bite or an infected dog licking broken skin.
Where do you find it? A risk throughout most of the world (even bat bites in Britain can give you rabies).
The lowdown: Invariably fatal once the symptoms start.
What you can do: Protect yourself with pre-travel immunisation. Know how to thoroughly clean a wound after any bite, and how to access post-bite jabs as soon as you can. Carry a rock to hurl at threatening packs of dogs.
What is it? Parasitic disease causing skin ulcers that almost heal then break down again and again.
Where do you find it? Quite common in the tropics and subtropics, especially the Middle East, as well as central and southern America.
The lowdown: Treatment isn’t easy and admission to hospital is the norm to achieve a cure.
What you can do: Report weird symptoms promptly to a doctor to get a diagnosis.
What is it? Infectious disease causing fever, headache, aches, profuse sweating, chills, weight loss, depression and joint pains.
Where do you find it? Common throughout the world except northern Europe, North America and Australia and New Zealand.
The lowdown: Seldom life-threatening but can lay a traveller low for many months; diagnosis is often delayed.
What you can do: Take only boiled or pasteurised milk. Avoid unpasteurised cheese.
What is it? Often a mild infection causing chills, cough, chest pain, shortness of breath, headache, clay-coloured stools, and sometimes even jaundice.
Where do you find it? Worldwide, especially where cattle, sheep and goats are giving birth; it can be acquired through aerosol inhalation in barnyards, through unpasteurised cheeses and occasionally from a tick-bite.
The lowdown: Because Q fever often causes only mild symptoms, it is difficult to know how common it is, but travellers are sometimes hospitalised with it; Q fever is treatable with antibiotics.
What you can do: Take care which animals you pet and which cheeses you select. Protect yourself from tick bites by wearing repellents and long clothes.
What is it? One of several forms of infective jaundice, causing fatigue, yellowing of the skin and whites of the eyes, and clay-coloured stools.
Where do you find it? Common in many non-industrialised nations especially south Asia and tropical Latin America.
The lowdown: Probably quite common in backpackers; can be a very mild illness.
What you can do: There isn’t a vaccine yet, so prevention involves eating thoroughly cooked food and drinking safe water.
Dogs: can harbour rabies, leishmania, echinococcus, gastroenteritis, Q fever
Pigs: can harbour cysticercosis, gastroenteritis
Cows: can harbour brucellosis, TB, gastroenteritis, listeria, Q fever
Rats: can harbour leptospirosis, gastroenteritis, Q fever, various haemorrhagic fevers
Monkeys: can harbour rabies, green monkey disease, ebola