Introduction

Diseases that are spread by parasites or by proximity to an infected person thrive in poor and overcrowded living conditions. In this section you will find tuberculosis and typhus.

Tuberculosis

Causative Agent

Mycobacterium tuberculosis

Primary Host

Humans, their domestic animals and many mammals

Spread by

Inhalation of bacilli.

Fatality Rate

Untreated or untreatable 25%-33%
In areas with good health services 8%-12%

Birthplace

Unknown. The bacillus is closely related to many common soil and environmental bacilli.

Endemic Today

In all human populations. Approximately one person in three carries the bacillus, although it is inactive in the majority.

Earliest Known

Evidence of tuberculosis in Egyptian mummies.

First Significant in Europe

Eighteen century, although present earlier. The spread of tuberculosis is closely linked to the spread of urbanisation and industrialisation.

Major Outbreaks

Tuberculosis is not subject to the cyclic outbreaks of plagues. In 1993, the World Health Organisation declared tuberculosis to be a global emergency. It is currently globally epidemic with some areas of low incidence.

Control and Treatment

Before effective treatment was available, tuberculosis was controlled, where possible, by sending the patients to isolation hospitals. These emphasised a regime of fresh air and a healthy diet.

Today Britain and a several other countries, mostly in Europe, routinely vaccinate against tuberculosis, using bacillus Calmette Guerin (BCG), which was developed in 1920. In Britain the vaccination is carried out on school children aged 12-14. Administering the vaccine to a person already sensitised to tuberculosis can have adverse side effects and Britain carries out a skin sensitivity test before vaccination.

The bacilli changing between active and dormant stages complicate the treatment of tuberculosis. A regime of drugs will produce an apparent cure within a few weeks, but a course of treatment lasting 6-8 months is required to destroy all dormant bacilli. There are five drugs commonly used to combat tuberculosis and it is necessary to use a cocktail of at least three of them in combination. However, poor drug administration regimes have lead to the development of a strain, multidrug-resistant tuberculosis, which is resistant to the two most powerful anti-tuberculosis drugs.

Situation Today

Tuberculosis is the most dangerous disease on the planet and it is spreading rapidly. Globally, one person is newly infected every second. Estimates put the expected death toll at anything from 35 million in the next 20 years to as many as 30 million in the next decade.

HIV and tuberculosis form a deadly combination. HIV weakens the immune system and anyone already infected with the bacillus is much more likely to develop active tuberculosis. In turn, tuberculosis is a leading cause of death among the HIV-positive.

Compared to the global average of 33% of the world’s population infected with tuberculosis, the current rate in Britain is 13% and in the USA is 7%. However, among the homeless in London, the rate is 25%, while among the homeless in San Francisco it is 30% (1995 figures).

Top of Page

Typhus

Causative Agent

Rickettsia prowazekii

Primary Host

Humans

Spread by

Rubbing infected faecal matter from the human body louse, or crushed louse, into a wound, usually by scratching or by rubbing the bite of the louse.

Fatality Rate

Among human body lice 100%

Among humans 1%-20%

Endemic Today

Highlands and cold areas of Africa, Asia and Central and South America.

Earliest Known

It has been suggested as the cause of the Plague of Athens in 430BC.

First Significant in Europe

First identified at the siege of Gianada 1489-90.

Major Outbreaks

Typhus, although known as ship’s fever or jail fever, is best described by its alternative name, war fever. It was a decisive factor at Naples in 1528 and at Metz in 1552. Hungary became known as the graveyard of the Germans, following the death of 30,000 troops in 1542 while another epidemic in 1566 scattered the troops of Maximilian II. The disease travelled with armies throughout the seventeenth and eighteenth century and was a major factor in the Retreat from Moscow in 1812. However, neither the American Civil War, nor the Franco-Prussian War spawned outbreaks of the disease. The Crimean War showed that the disease was still rife in Eastern Europe, a pattern that would be repeated in World War 1. In that war there were no outbreaks of epidemic typhus on the Western Front, but it killed at least 3 million in and around the Eastern Front. Again, in World War 2, typhus was very active on the Eastern Front but an outbreak in Naples in 1943-4 and post-war outbreaks in Germany were cut short by the new wonder insecticide DDT.

Britain was relatively isolated from the disease, compared with continental Europe. There was a serious outbreak, starting in Cambridge in 1522, which lead to many deaths during the infamous Black Assizes. In 1643 it exploded through both armies at the Siege of Reading and another epidemic affected huge areas of the country in 1650. Between 1816 and 1819 it swept through the British Isles, apparently starting among the Irish already suffering from famine. The Royal Navy achieved a freedom from typhus that no other navy could match when it adopted the recommendations of James Lind, best known for his efforts against scurvy. He suggested that sailors should be stripped, scrubbed, shaved and issued with clean clothes. These measures contributed greatly to the health, and indirectly to the effectiveness, of Royal Navy personnel.

Control Measures

The simplest measure is cleanliness, to prevent infestation with body lice. Where this is impractical, heating clothing to 70C for at least one hour may be used to control occasional infestations. In emergency situations, chemical control of lice is recommended and will provide protection for several weeks. DDT has long been replaced with more environmental friendly insecticides. If the disease is contracted, a single drug dose provides a cure. However, in war areas access to treatment may not always be available.

Situation Today

Outbreaks still occur in war areas and in crowded living conditions, such as refugee camps but have largely been restricted to Africa since World War 2.

Top of Page