Anna Bonnici's two year-old brother Giacchino dies, and a female slave in the household becomes sick soon afterwards but is able to recover.
The cause of these deaths is still not identified when another member of the family, seven-year-old Teresa, dies from similar symptoms on January 13.
Members of the Agius family, relatives of the Bonnicis, also become ill and die, and this raises alarm and the authorities close the houses of the victims.
Matteo Bonnici contracts the disease as well and dies on January 25.
Further cases appear in the next few days, and on January 28, the health authorities hold a secret meting and conclude that the disease is probably the plague.
Attempts to contain the epidemic begin immediately and all suspected cases are isolated, but the disease continue to spread rapidly.
Some people panic and leave the cities for the countryside, leave the island or lock themselves in their homes, but there are many others who maintain their daily routines, contributing to the spread of the disease.
By March 2, there are one hundred deaths.
The first death outside Valletta occurs on 8 March in Attard.
The disease appears in the Three Cities, starting from Senglea on 14 February, followed by Cospicua on March 8 and Birgu on March 11.
The epidemic continues to spread throughout the rural towns and villages, including Birkirkara on March 10, Rabat on March 11 and eventually to Kirkop, Qrendi, Qormi, Balzan, Siġġiewi, Żebbuġ and Żurrieq by the end of the month.
In April, the epidemic appears in Lija, Tarxien, Luqa, Għargħur, Naxxar and Mqabba, and in May it appears in Gudja, Żejtun and Mosta.
The course of the epidemic is somewhat variable and it goes through a number of ebbs and flows, and it spreads extensively throughout the main island of Malta at its peak, particularly the densely populated urban area around the Grand Harbor.
The city of Mdina, the village of Safi and the island of Gozo remain free of the disease.
