Friday 14 April 2023

Outbreak of Pneumococcal Meningitis in Togo.

Since mid-December 2022, Togo has been responding to a Meningitis outbreak that has so far resulted in a total of 141 cases and 12 deaths (a fatality rate of 8.5%), with almost half of the cases affecting children and young adults between 10 and 19 years of age. Overall, 22 samples have been confirmed as Streptococcus pneumoniae, according to a press release issued by the World Health Organization on 11 April 2023.

Togo is located in the African Meningitis Belt, with seasonal outbreaks recurring every year. However, the current outbreak is concerning due to different concomitant factors, including the security crisis in the Sahel which causes population movements, and suboptimal surveillance capacity. This is also the country’s first time dealing with a Pneumococcal Meningitis outbreak.

An incident management system has been established to coordinate the outbreak response activities, and the World Health Organzation is supporting the shipment of antibiotics (ceftriaxone) to improve case management.

The World Health Organzation assesses the overall risk posed by this outbreak as high at the national level, moderate at the regional level, and low at the global level.

On 15 February 2023, the Ministry of Health of Togo officially declared a Meningitis outbreak in Oti Sud District, Savanes Region, in the northern part of the country. From 19 December 2022 to 2 April 2023, a total of 141 suspected cases of meningitis with 12 deaths have been reported from Oti Sud District, corresponding to an attack rate of 112 per 100 000 population.

Number of reported meningitis cases and deaths, 19 December 2022 (week 51 of 2022) to 2 April 2023 (week 13 of 2023), Oti Sud District, Savanes Region, Togo. World Health Organization.

A total of 118 cerebrospinal fluid samples were collected from suspected cases, of which 22 were confirmed by polymerase chain reaction and culture for Streptococcus pneumoniae at the national reference laboratory (81 samples were negative and the results for 15 samples are pending).

The most affected age group is 10–19 years (66 cases, or 47% of the total), followed by the over 30-year age group with 20% of cases (28), and the 20-29 year age group with 15% of cases (22). There is no difference in the case distribution by gender, with 71 (53%) cases reported among males.

Togo introduced the 13-valent Pneumococcal Conjugated Vaccine in 2014, which is currently administered in three doses at the first, second and third months of life. The administrative 13-valent Pneumococcal Conjugated Vaccine coverage in the Savanes Region is 100% for the third dose, but the immunization history is not available for the individual cases, and it is not known if the serotype(s) involved are covered by the vaccine. Additionally, the most affected age groups were born before the 13-valent Pneumococcal Conjugated Vaccine introduction in 2014 and could have not received the vaccine.

Meningitis is a devastating disease with a high case fatality rate and serious long-term complications (sequelae). It remains a major global public-health challenge. Many organisms can cause Bacterial Meningitis. Neisseria meningitidisStreptococcus pneumoniae, and Haemophilus influenzae type b constitute the majority of all cases of Bacterial Meningitis and 90% of Bacterial Meningitis in children. It is estimated that about one million children die of Pneumococcal Disease every year.

Streptococcus pneumoniae is an Encapsulated Bacterium, and about 90 distinct Pneumococcal serotypes have been identified throughout the world, with a small number of these serotypes being able to cause disease. Pneumococci are transmitted by direct contact with respiratory secretions from patients and healthy carriers. Serious Pneumococcal infections include Pneumonia, Meningitis and Febrile Bacteraemia; Otitis Media, Sinusitis and Bronchitis are more common but less serious manifestations. The incubation period is two to 10 days. Pneumococcal Meningitis has a high case fatality rate (36%–66%) in the African Meningitis Belt, requires longer treatment than Meningococcal Meningitis, and is more frequently associated with severe sequelae.

Diagnosis of Bacterial Meningitis typically requires lumbar puncture. In the absence of lumbar puncture, diagnosis can only be suspected through clinical examination (but not confirmed, except with a positive blood culture). Culture and polymerase chain reaction are confirmatory tests for Bacterial Meningitis. Rapid diagnostic tests can support the diagnosis but are not confirmatory. Identification of serotypes or serogroups and susceptibility to antibiotics are important to define control measures. Molecular typing and whole genome sequencing can identify additional differences between strains and inform public health responses.

A range of antibiotics is used to treat Meningitis, including penicillin, ampicillin, and ceftriaxone. During epidemics of Meningococcal and Pneumococcal Meningitis, ceftriaxone is the drug of choice. Nevertheless, Pneumococcal resistance to antimicrobials is a serious and rapidly increasing problem worldwide.

Togo is part of the African Meningitis Belt and annually records Meningitis cases and deaths. Although the country has experience in the management of Meningococcal Meningitis outbreaks over the past years, the current Streptococcus pneumoniae outbreak is unusual as the country has never managed a Pneumococcal Meningitis outbreak in the past, and national capacity is limited. 

To date, no imported cases have been reported in neighbouring countries. However, several factors are likely to increase the risk of spread, including the country's location in the African Meningitis Belt; the epidemic season, which typically runs from January to June; constraints in the provision of vaccination services, which do not allow for optimal vaccination coverage to protect the population; the fact that the main age groups affected by the outbreak are not protected by the routine vaccination against Streptococcus pneumoniae introduced in Togo in 2014; the security crisis in the Sahel, affecting the Savanes Region, hampering public health interventions and causing population movements; the precarious economic conditions in the country, particularly in the Savanes Region; and the sub-optimal surveillance capacity for early case detection, diagnosis and treatment in the Oti Sud District. Neighbouring countries are also in the African meningitis belt, and the Oti Sud district borders Ghana and Benin, making it possible for the disease to spread to other countries in the region.

Considering the above-described situation, the World Health Organization assesses the overall risk posed by this outbreak as high at the national level, moderate at the regional level, and low at the global level.

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter