Below is a series of brief descriptions of some of the more serious diseases that international travellers may encounter.
- Hepatitis A
- Ebola virus
- Lassa fever
- Murburg virus
Typhoid fever is a life-threatening illness caused by the bacterium Salmonella Typhi. It belongs to the Salmonella group which contains nearly 2,000 different types causing mild diseases such as food poisoning, through to the more serious disease of typhoid fever. Paratyphoid fever is a similar but less severe variant.
Tetanus is a potentially fatal disease which is caused by an infection of the bacterium Clostridium Tetani. The bacteria enter the body through a wound where they grow and produce a powerful toxin which circulates in the blood and causes muscular rigidity and painful muscle contractions. Death is usually caused by respiratory problems and exhaustion.
Poliomyelitis, normally referred to as polio is caused by a virus which is spread from person-to-person primarily through faecal contamination of food and water although it can also be spread by droplet transfer. Initially, infection of the gut can spread to the spinal cord or brain where it can cause paralysis. In the days before widespread vaccination it tended to occur in epidemics.
This is a viral disease that causes inflammation of the liver. It occurs worldwide and is especially prevalent in areas of poor sanitation and hygiene.
Many children in developing countries are infected with the virus at an early age, usually without symptoms. Past infection with hepatitis A virus gives life long immunity.
Cholera is a bacterial infection of the gastro-intestinal tract caused by the bacterium Vibrio Cholerae. These bacteria are typically ingested by drinking water contaminated by improper sanitation or by eating improperly cooked fish, especially shell fish.
Meningitis is an infection that causes inflamation of the membranes and fluid that surrounds the brain and spinal cord. It can be caused by a viral or bacterial infection.Viral meningitis is generally less severe and resolves without specific treatment, while bacterial meningitis (meningococcal) can be quite severe and may result in brain damage, coma or even death.
Diphtheria is an infection caused by a bacterium called Corynebacterium diphtheriae that causes a moderately sore throat. Sometimes the lining of the throat may swell to form “a false membrane” which can cause difficulties in breathing.
In its early stages, diphtheria may be mistaken for a severe sore throat. In severe cases the neck tissue may become very swollen and in tropical countries the infection can occur in skin ulcers. It is mainly spread by droplets expelled from the nose and mouth usually by breathing in diphtheria bacteria after an infected person has coughed, sneezed or even laughed. It can also be spread by handling used tissues or by drinking from a glass used by an infected person.
This is a viral infection that is acquired from the saliva of an infected or rabid animal, usually a dog or cat. In most cases infection results from a bite but even a lick on an open cut or sore may be enough.
Symptoms start with itching and tingling at the site of the healed bite and then rapidly progresses to include headache, fever, spreading paralysis, confusion, aggression and hydrophobia (fear of water).
It may take many weeks or months for symptoms to develop although it is usually two to eight weeks. Animals may be infectious for five days before they develop symptoms.
Tuberculosis (TB) is an airborne, infectious disease caused by a bacterium calledMycobacterium tuberculosis which primarily affects the lungs.
While both preventable and curable, TB remains one of the world’s major causes of illness and death.
Approximately one-third of the world’s population carry the TB bacteria, almost 9 million of whom develop “active” TB each year, which can then be spread to others.
Also known as bilharzia, is a disease caused by parasitic worms called schistosoma. They belong to the family of flat worms known as trematodes or flukes. There are several different species e.g. S. mansoni, S. haematobium, and S. japonicum. About 200 million people are thought to be infected world-wide.
The infection occurs when the skin comes into contact with contaminated fresh water which contains a certain type of snail that carry the schistosomes.
Fresh water becomes contaminated by Schistosoma eggs when people who are infected urinate or defaecate in the water. The eggs then hatch, and if the snails are present in the water, the parasites invade the snails and grow and develop inside them. The parasites eventually leaves the snails and enter the water where they can survive for up to 48 hours
Leptospirosis is a bacterial disease caused by bacteria of the genus Leptospira. It affects humans and animals and causes a wide range of symptoms, including high fever, severe headache, chills, muscle aches, and vomiting, and may include, red eyes, abdominal pain, diarrhea, or a rash although some infected persons may have no symptoms at all. If the disease is not treated, then kidney damage, meningitis liver failure, respiratory distress and even death may result.
Outbreaks of leptospirosis are usually caused by exposure to water contaminated with the urine of infected animals. Many different kinds of animals carry the bacteria such as cattle, pigs, horses, dogs, rodents, and wild animals..
Fever is a severe, often-fatal disease that has appeared sporadically since its initial recognition in 1976.
The disease is caused by infection with Ebola virus, named after a river in the Democratic Republic of the Congo in West Africa, where it was first recognized. The virus is one of two members of a family of RNA viruses called the Filoviridae. There are four identified subtypes of Ebola virus. Three of which have caused disease in humans.
Infections with Ebola virus are acute. There is no carrier state. Because the natural reservoir of the virus is unknown, the manner in which the virus first appears in a human at the start of an outbreak has not been determined. However, it is thought that the first patient becomes infected through contact with an infected animal, possibly a primate or a fruit bat. Infection can occur from ingestion of infected meat.
is an acute viral illness that occurs in West Africa. The illness was discovered in 1969 and named after the town in Nigeria where the first cases originated. The virus, a member of the virus family Arenaviridae is animal-borne and is acquired from a particular kind of wild rodent known as the multimammate rat.
In the areas of Africa where the disease is endemic, Lassa fever is a significant cause of mortality. While it is mild or has no observable symptoms in about 80% of people infected, the remaining 20% contract a severe multisystem disease. Lassa fever is also associated with occasional epidemics, during which the case-fatality rate can reach 50%.
The disease is known to be endemic (constantly present) in Nigeria, Sierra Leone, Liberia, Guinea and the Central African Republic, and there is evidence of infection in nearby countries including Mali, Senegal, and the Democratic Republic of Congo. However, because the rodent species which carry the virus are found throughout West Africa, the actual geographic range of the disease may extend to other countries in the region.
Marburg haemorrhagic fever is a rare, severe type of haemorrhagic fever which affects both humans and animals. It is caused by a genetically unique RNA virus of the filovirus family, and its recognition led to the creation of this virus family. The Ebola virus is the only other known member of this family.
Marburg virus is indigenous to Africa but the actual geographic area to which it is native is unknown, but could include parts of Uganda and Western Kenya, and Zimbabwe. As with Ebola virus, the actual animal host for Marburg virus also remains a mystery.
Just how the virus is first transmitted to humans is unknown. However, as with some other viruses which cause haemorrhagic fever, humans who become ill with Marburg fever may spread it to other people.