The ministry announced the clusters on Monday, September 28. One case has been confirmed by laboratory testing and eight others are under investigation, including two deaths.
The national surveillance and response manual sets out how health authorities are to detect cases, confirm infections, trace contacts, provide treatment, contain transmission and adapt vaccination efforts during an outbreak.
The document comes as diphtheria remains a concern in populations with insufficient vaccination coverage. According to the manual, the global burden of diphtheria fell by more than 80% between 1980 and 2018. Recent outbreaks nevertheless show that respiratory diphtheria can resurface where vaccination gaps develop. At least eight countries reported outbreaks in 2024, including five in the African region.
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The COVID-19 pandemic disrupted routine vaccination and disease surveillance worldwide, leaving more children and adults insufficiently protected. Morocco has faced similar challenges, according to the manual.
Despite gains made through the National Immunization Program, the pandemic and vaccine hesitancy contributed to temporary declines in coverage in some areas, creating pockets of susceptibility, particularly among older children, adolescents and certain adult groups.
The manual also points to increased mobility, communal settings such as schools, prisons and workplaces, and regional circulation of infectious agents as factors that can increase the risk of sporadic cases and clusters.
What is diphtheria?
Diphtheria is caused by bacteria of the Corynebacterium genus, mainly C. diphtheriae. Strains carrying the toxin gene can cause cardiac and neurological complications.
The disease is transmitted mainly through respiratory droplets released by coughing, sneezing or talking. It can also spread through close physical contact with an infected person or asymptomatic carrier, or through contact with infected skin lesions. Some species, such as C. ulcerans, can be transmitted through infected animals or unpasteurized dairy products.
The manual puts the basic reproduction number at 6 to 7. The incubation period is usually two to five days and can extend to 10 days.
The overall case-fatality rate is estimated at 5% to 10%. Without antibiotics, an infected person can remain contagious for two to six weeks, and sometimes longer in chronic carriers. With appropriate treatment, infectiousness generally becomes negligible after 48 hours.
The manual estimates that vaccination coverage of 80% to 85% is needed to maintain community protection.
How health authorities define a case
The surveillance system has four main objectives: detecting suspected cases or clusters early, confirming cases quickly, identifying transmission patterns and populations at risk, and assessing the effectiveness of response measures.
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Under the manual, a suspected case is a person with an upper respiratory tract infection, such as pharyngitis, nasopharyngitis, tonsillitis or laryngitis, accompanied by an adherent pseudomembrane.
The thick, grayish membrane can bleed heavily if an attempt is made to remove it.
A person can also be classified as a suspected case if they have a compatible upper respiratory infection accompanied by a marked deterioration in their general condition or signs suggesting cardiac, neurological or kidney complications.
A probable case is a suspected case epidemiologically linked to a laboratory-confirmed case, or a suspected case in which direct examination identifies Gram-positive bacilli.
A confirmed case is a suspected case confirmed by PCR or bacterial culture.
A death is classified as diphtheria-related only when it occurs in a confirmed case, results from a complication of the disease and has no other possible cause.
All health facilities must report suspected cases immediately
The surveillance system covers all health facilities, including primary healthcare centers, private practices, public and private hospitals and laboratories.
Any suspected or confirmed case must be reported immediately to local and national health authorities. Notification is made by telephone as soon as the case is detected.
The healthcare facility alerts the Provincial Unit for Epidemiological Surveillance, Health Security and Environmental Health (UVSSSE). Laboratories notify the Epidemiological Surveillance Service (SSE) or the National Public Health Emergency Operations Center (CNOUSP).
The UVSSSE then launches an epidemiological investigation in coordination with the Regional Public Health Emergency Operations Center (CROUSP).
Each suspected case is documented through a detailed investigation form covering the patient’s identity, school address, symptoms, vaccination status and source of vaccination, recent travel, similar cases among contacts and identified contacts.
Any death attributed to diphtheria, regardless of where it occurs, must undergo an audit using a dedicated form.
Authorities must also maintain an updated Excel database. A weekly report is sent between the different levels of the surveillance system every Monday by noon at the latest.
The manual specifies that even when there are no cases, authorities must report “zero cases.”
Samples must be collected before antibiotics are given
Laboratory confirmation relies on identifying the bacteria from a throat or skin-lesion sample.
Testing includes culture on a specific medium, species identification and PCR testing for the toxin gene.
The manual lists three reference laboratories:
- The laboratory of the Rabat Military Teaching Hospital;
- The microbiology laboratory of the Ibn Sina Military Teaching Hospital in Marrakech;
- The bacteriology and virology laboratory of Ibn Rochd University Hospital in Casablanca.
The Directorate of Epidemiology and Disease Control (DELM) updates the list of authorized laboratories. The Epidemiological Surveillance Service and CNOUSP coordinate the transport of samples.
A technical annex from the bacteriology laboratory of Rabat’s Mohammed V Military Teaching Hospital details the sampling procedure.
Samples must be collected before any antibiotic treatment is started. Each suspected case requires a throat swab and a nasal swab.
Healthcare workers collecting samples must wear a long-sleeved gown, an FFP2 mask, gloves, eye protection where there is a risk of splashing, a cap and shoe covers.
Samples are transported in triple packaging marked “Biohazard.” They should preferably reach the laboratory within two hours at room temperature. If transportation takes more than 24 hours, samples are stored at between 2°C and 8°C.
At the beginning of an outbreak, all suspected cases are tested. Once the outbreak has been characterized, priority is given to severe cases and cases emerging in new areas.
Treatment starts as soon as diphtheria is suspected
The manual describes diphtheria as a therapeutic emergency. Treatment should begin as soon as the disease is suspected clinically, without waiting for laboratory confirmation.
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The goals are to neutralize circulating toxin, eliminate the bacteria, prevent complications and stop transmission.
Hospitalization is recommended, particularly when there are signs of severe disease. Patients should be placed in individual rooms under respiratory droplet precautions and wear surgical masks when moving around the facility. Healthcare workers must wear FFP2 masks. Contact precautions are also required when skin lesions are present.
Diphtheria antitoxin is essential for respiratory or systemic forms of the disease. It neutralizes toxin circulating in the body but cannot neutralize toxin that has already attached to tissues, making early administration critical.
The antitoxin is not used as post-exposure prophylaxis.
Antibiotics are given systematically. The manual recommends penicillin or a macrolide to eliminate the bacteria, stop toxin production and reduce transmission.
Treatment lasts 14 days, except for azithromycin, which is prescribed for five days. A bacteriological test is performed after treatment to confirm that the bacteria have been eradicated.
Patients are also monitored for cardiac complications, particularly myocarditis, as well as neurological complications.
Vaccination is given during recovery because having diphtheria does not provide sufficient immunity.
Isolation can be lifted after clinical improvement and at least 48 hours of effective antibiotic treatment.
The manual warns that pseudomembranes can spread to the larynx and bronchi, causing potentially fatal airway obstruction, particularly in children. The membranes can also detach and suddenly cause complete airway blockage.
Myocarditis generally develops between the 10th and 14th day, but can occur anytime from the first to the sixth week, even as respiratory symptoms improve. Heart rhythm disturbances and heart blocks are associated with high mortality.
The toxin can also cause nerve damage, although this is rare, as well as kidney complications.
Contacts are divided into three risk levels
A contact is anyone closely exposed to a case during the period when the patient is contagious. The manual includes family members, fellow inmates, classmates, colleagues, healthcare workers and visitors.
High-risk contacts include household members, fellow inmates, dormitory residents and anyone directly exposed to the patient’s saliva, cough or sneezing.
Vaccination status does not exclude someone from this category.
High-risk contacts receive vaccination and systematic antibiotic chemoprophylaxis. They are subject to active daily monitoring for 10 days, with mandatory exclusion from school or work during the same period.
Moderate-risk contacts include classmates, office colleagues and prison staff who are regularly exposed.
Vaccination is offered after checking their vaccination history. Chemoprophylaxis depends on the circumstances, including whether there is a cluster, whether the exposure occurred in a closed setting and whether the person is at increased risk of complications. The decision is made in consultation with health authorities.
Monitoring is passive, meaning contacts monitor themselves for symptoms and have a designated health contact available.
They are excluded from school or work until 48 hours after starting prophylaxis, provided they have no symptoms.
Low-risk contacts include people exposed only briefly or occasionally, such as someone who crosses paths with a patient in a corridor.
Vaccination is recommended when vaccination status is unknown. No chemoprophylaxis or exclusion is required. Individuals are instead advised to monitor themselves and seek medical attention if symptoms appear.
How vaccination is adapted during an outbreak
During an outbreak, vaccination serves both as an immediate response measure and as a longer-term prevention tool.
The manual provides for targeted or mass vaccination campaigns, prioritizing children under five, school-age children, older people and healthcare workers.
Vaccination efforts cover affected areas as well as neighboring areas considered at high risk. In those areas, everyone in the targeted age group is vaccinated regardless of their previous vaccination status.
Unvaccinated contacts receive a complete series. Partially vaccinated contacts receive the missing doses.
If more than five years have passed since the last dose, a booster is generally recommended during an outbreak.
The diphtheria-tetanus-pertussis vaccine (DTP) is recommended for children aged 1 to 7. The diphtheria-tetanus (DT) vaccine is recommended for people over 7, adolescents and adults.
For people who have never been vaccinated, the catch-up schedule consists of three doses: the second at least four weeks after the first and the third at least six months after the second. Two booster doses follow, with at least one year between them.
The manual sets out one key principle: a vaccination series should not be restarted. Instead, missing doses should be administered as soon as possible while respecting minimum intervals.
In Morocco, primary childhood immunization is provided through the pentavalent vaccine at 8, 12 and 16 weeks. Two DTP booster doses are given at 18 months and 5 years.
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The World Health Organization recommends six doses during childhood, followed by regular boosters in adulthood.
Measures include more than vaccination
The response system also includes field measures such as promoting handwashing and respiratory hygiene and cleaning and disinfecting surfaces in schools and other communal settings.
Suspected cases and unprotected contacts may be temporarily isolated or have their activities restricted.
Active surveillance is planned in schools, nurseries and health centers, particularly in affected communities.
At the coordination level, the system provides for the creation of a regional unit to monitor the epidemiological situation.
Logistical preparations include the distribution of antibiotics and personal protective equipment.
The overall approach is designed to move quickly from detection to investigation, laboratory confirmation, treatment, contact management and targeted vaccination in order to contain transmission and close the immunity gaps that can allow diphtheria to return.
