During the 18th century the town had a reputation as being unhealthy and prone to frequent outbreaks of serious epidemics. 

In 1764 the diarist William Thomas blamed the death of 40 residents in less than 14 days on the vapours emitting from the nearby coal mine, stating "Was buried in Lantrissent a young man from ye fever and about 200 have been buried in Llantrissent this 13 months last past as young Dr Bates reporteth…all yt die ar ym this side of yet Town and many of ym belonging to ye mine pits, except the mine pits were stoped the most of yet town and parts about will die. But in vain when God’s sweitch is beating.”

Asiatic cholera, spread by bacteria in contaminated water or food, swept across Europe in 1831 and 1832. The outbreak of 1848/49 was far more serious and over 3,000 people died in the county of Glamorgan. 

In Cardiff there was a total of at least 350 deaths.6 Merthyr Tydfil was the worst affected town, suffering a total of 1,389 deaths from cholera, perhaps more The cholera epidemic gave a sense of urgency to the need to carry out sanitary improvements across Wales. The Public Health Act of 1848 permitted the establishment of local Boards of Health and the new position of Medical Officers of Health. 

It was an enabling, not a compulsory act and implementation depended on the initiatives of local communities. The work of the local Boards of Health reflected the tensions in local politics and their actions and effectiveness varied.8 There was little central government direction and powers were limited. 

Some 17 towns in south Wales petitioned to form Boards of Health around the time of the cholera epidemic, among them Cardiff and Swansea in 1848, Merthyr Tydfil in 1850, Aberdare in 1854 and Maesteg in 1858. All brought about some improvement in sanitation, but the effectiveness of reform depended greatly upon the balance of local interests. In Merthyr Tydfil, despite some opposition from local ironmasters concerned to safeguard their own industrial water needs, a public water supply was established. A reservoir was completed in 1863, and sewage pipes were laid underground. 

There were many episodes of typhoid, dyptheria and measles affecting the population and in 1872 many residents died from smallpox. On this occasion a row of cottages to the rear of Swan Street, was named Glyn Terrace since the occupants were mostly miners who worked in the Glyn Colliery. When many of the families, probably Cornish settlers, succumbed to the disease, the houses were set alight in an effort to rid the town of smallpox. Some of the family graves are inscribed, “Not To Be Opened” in the parish church yard.

A newspaper report of the period stated: “This dreadful disease continues to a fearful extent in the town and neighbourhood, and we regret to state that five deaths occurred within the last week, and several fresh cases have broken out. There appears to be an impression abroad that the use of disinfectants has been greatly neglected. We believe that if small quantities of disinfecting matter were supplied by the medical profession to those persons who neglect making use of it, through total ignorance of its worth, it would certainly tend to have a very beneficial effect.”

Compulsory vaccination against smallpox was first introduced in 1852, yet in the period 1857 to 1859, a smallpox epidemic killed 14,244 people. In 1863 to 1865, a second epidemic claimed 20,059 lives. In 1867, a more stringent compulsory vaccination law was passed and those who evaded vaccination were prosecuted. After an intensive four year effort to vaccinate the entire population between the ages of 2 - 50, the Chief Medical Officer announced in May 1871 that 97.5% had been vaccinated. In the following year, 1872, the country experienced its worst ever smallpox epidemic which claimed 44,840 lives. 

Between 1871-1880, during the period of compulsory vaccination, the death rate from smallpox leapt from 28 to 46 per 100,000 population. The need for better drainage and a sewerage system in Llantrisant was recognised as the reliance on a single Town Pump was considered inadequate and unhealthy. Investments were made into the drainage and water supplies and a Sanitation Board overseeing the public health concerns of the area. 


The Black Death

The Black Death killed 1.5 million people out of an estimated total of 4 million people in Britain between 1348 and 1350. No medical knowledge existed to cope with the disease. After 1350, it was to strike the country another six times by the end of the century.

We have no firm evidence of the impact it had on Llantrisant, but Wales as a whole lost a quarter of its population due to this “Great Mortality” plague. Most of those deaths occurred in just 1349 alone.

One can assume that it had the same effect on Llantrisant, claiming the lives of many of its new Freemen and even those veterans of Crecy. Arguably the 1346 Charter was also lost during this time and required a Confirmation Charter in 1424. Today the Court Leet Ceremony refers to a period "Before the memory of man", which relates specifically to this period prior to the Black Death

It was believed to have arrived from Asia in late 1348. It was also to have a major impact on the country’s social structure which lead to the Peasants Revolt of 1381.

There were three main strains to the disease; bubonic, which was caused by victims being bitten by rat fleas; pneumonic, caused by breathing in the infection; and septicemic, which was invariably 100% fatal. Whatever the cause of the infection, death was often very quick for the weaker victims. By Spring 1349 the Black Death had killed six out of every ten Londoners.

The customs collectors at Carmarthen – then an important port – were amongst the first victims but soon the disease spread across the whole country. Caldicot was badly hit, as were the west Wales towns of Pembroke and Haverfordwest. The lead miners of Holywell, a close knit community, were virtually wiped out.

To the people of the Welsh towns and villages the plague was a manifestation of evil. They wondered what they had done to bring down the wrath of God upon their heads like this. 

Written evidence from the time indicates that nearly all the victims died within three days though a small number did last for four days. In towns and cities people lived very close together and they knew nothing about contagious diseases. If they did, they would have avoided close contact with others if they themselves were ill or if others around them were ill. They would also have been careful to cover their mouth and nose when coughing or sneezing. Additionally, the disposal of bodies was very crude and helped to spread the disease still further as those who handled the dead bodies did not protect themselves in any way.