At highest risk are children, who account for many of the more than 280 suspected diphtheria cases and 33 associated deaths reported as of Tuesday, according to the World Health Organization (WHO).
Most of the cases and deaths involved children who had not been immunized against the disease, a contagious and potentially fatal bacterial infection that spreads easily, WHO said.
“Left unchecked, diphtheria can cause devastating epidemics, mainly affecting children,” Tarik Jasarevic, a WHO spokesman, told the Thomson Reuters Foundation by email.
The diphtheria spread is inevitable in Yemen due to low vaccination rates, lack of access to medical care and so many people moving around and coming in contact with those infected, said WHO and officials with Medecins Sans Frontieres (MSF).
Saudi aggression has killed more than 10,000 people and displaced more than two million others.
Diphtheria spreads as easily as the common cold through sneezing, coughing or even talking, according to health officials.
Yemen also is battling a cholera epidemic that has infected about one million people. The epidemic, which worsened this past April, has caused more than 2,000 deaths, WHO said in October.
Diphtheria could be more fatal than cholera, especially among unvaccinated children under 5 years old, according to MSF.
As many as two in five diphtheria cases end in death, MSF said.
“There is the potential for a larger-scale outbreak of diphtheria, given that not everyone has been vaccinated,” said Marc Poncin, emergency coordinator in Yemen for the medical charity, also by email.
Calling it “very worrisome,” Caroline Boustany, an aid worker with the International Rescue Committee, told the Foundation: “We have a spike in cases of a very easily preventable disease.”
Yemen also faces soaring food prices and fuel shortages, and some 8.4 million Yemenis are considered to be a step away from famine, the United Nations said on Monday.
The Saudi blockade impact limited supplies of desperately needed fuel, food and medicine, aid officials say.
“Even for patients who want to seek treatment, the blockade on fuel and consequent surge in prices means that they cannot afford to travel to the very few health centers still operational,” said Poncin of MSF.