Girl dies of diphtheria in Palermo: the symptoms, how it is contracted and why vaccines are crucial

The death of a young girl in Palermo from diphtheria – the child had not been unvaccinated – has once again brought attention to a disease that had not been seen in Italia for years. Whilst the search is on for ‘patient zero’ to trace who infected the four-year-old girl, the Palermo Local Health Authority has carried out swab tests on members of the girl’s family, and several members of her family have received the hexavalent vaccine.

Diphtheria is transmitted through direct contact between people (or, more rarely, via objects contaminated with the same secretions), and it is essential to have adequate vaccination coverage, with sufficient antibody levels. This means not only receiving the first dose of the vaccine in childhood but also having the necessary booster doses over time. The risks associated with diphtheria cannot be considered remote, even in Italy, given that in many parts of the world, including Italy, vaccination coverage – the WHO’s safety threshold is 95% – is inadequate or even non-existent, and pathogens can easily travel with people. In Italia, coverage in 2024 stood at 94.4 per cent, but with regional variations, as in Sicily – which had the lowest figure – it stood at 85.1 per cent.

“Diphtheria is a highly contagious infection caused by the bacterium Corynebacterium diphtheriae and, to a much lesser extent, by Corynebacterium ulcerans. Although the infection is usually localised in the nose, tonsils and soft palate, it can become potentially fatal due to the diphtheria toxin produced by the bacteria, which spreads via the bloodstream throughout the body, causing serious damage to vital organs. Whilst the bacteria remain localised at the site of infection, the diphtheria toxin they produce spreads via the bloodstream throughout the body, causing serious damage to the heart, liver, kidneys, adrenal glands and the peripheral nervous system. ‘Even if the infection is treated, the damage caused to the heart can be fatal,’ explains the ISS (the Italian National Institute of Health) in an FAQ page compiled by the Department of Infectious Diseases.

The symptoms of diphtheria usually appear 2 to 5 days after infection and may include: a greyish-white membrane covering the throat and tonsils (pseudomembranes); a sore throat; hoarseness; swollen glands (enlarged lymph nodes) in the neck; difficulty breathing and rapid breathing; a runny nose; fever and chills; and severe general fatigue. In some people, the infection may present with only mild symptoms or none at all. These people, unaware of their condition, are ‘asymptomatic carriers’ and, just like those who are ill, can spread the infection.

Those most at risk of contracting diphtheria are: children and adults who have not been vaccinated or whose vaccinations are not up to date; and unvaccinated people travelling to areas where diphtheria is endemic, such as South-East Asia, Africa and Brazil. In Italia and across Europe in general, cases of diphtheria are very rare. Diphtheria can be prevented with a safe and effective vaccine. The vaccination schedule provides for the vaccination of children in their first year of life (a basic course of 3 doses), using a combined vaccine that also protects against tetanus and whooping cough (paediatric DTaP) and administered alongside vaccines against hepatitis B, Haemophilus influenzae type b and polio (hexavalent vaccine). A booster is recommended in the sixth and twelfth years of life. Thereafter, a booster is recommended every 10 years using the trivalent diphtheria, tetanus and pertussis vaccine for adults (dTap). The dTap vaccine is recommended for women during every pregnancy, even if they have already been vaccinated or are up to date with their 10-yearly boosters.