Neisseria Meningitidis: Transmission, Symptoms & Prevention

Introduction

It is worth noting from the outset that Neisseria meningitidis (Nm) is an exclusively human pathogen. In the words of Seib and Peak (2019), "Neisseria meningitidis is a leading worldwide cause of sepsis and meningitis, with the highest incidence in infants, young children, and adolescents, resulting in significant morbidity and mortality" (p. 87). According to Rouphael and Stephens (2012), Nm was first identified in 1887 by a Viennese pathologist named Anton Weichselbaum. Rouphael and Stephens (2012) also observe that over time, Nm has evolved multiple mechanisms that enable the pathogen to effectively colonize a person's respiratory tract through relevant adaptations. This paper addresses not only the description and prevalence of Nm, but also its transmission, infection symptoms, and prevention efforts.

Description and Prevalence

Meningitis can be caused by a wide range of organisms, including — but not limited to — viruses, fungi, and bacteria. Nm is therefore one of the causes of meningitis, specifically bacterial meningitis. In addition to meningitis, Nm has been linked to a number of other conditions, including pneumonia, sepsis, and in some instances epiglottitis, endophthalmitis, and myocarditis (World Health Organization [WHO], 2018). In essence, Nm can be conceptualized as a potentially fatal infection of the meninges, with its most significant impact on the brain membrane of the affected individual. The disease is described as potentially fatal because, if left untreated, it carries a fatality rate of more than 50% (WHO, 2018).

Previous studies have identified a total of 12 Nm types, half of which can trigger epidemics and disease. At present, Types A, B, C, W, X, and Y have been associated with epidemics and disease (Centers for Disease Control and Prevention [CDC], 2019). As the CDC (2019) further observes, in the United States the most common Nm types are Y, C, and B — these are the types that trigger the highest number of illnesses in the country. It is also important to note that, as WHO (2018) points out, Nm has been observed across a wide range of situations, from large epidemics to small clusters and sporadic cases. Although people of all ages can be affected by Nm, those who appear to be most impacted are young people, preschool children, and infants.

The highest Nm infection rates in the world are largely concentrated in what the CDC (2020) refers to as the sub-Saharan Africa "meningitis belt." More specifically, infection rates in this region appear to be highest from December through June — that is, during the dry season. It therefore follows that people traveling to this region during this period face elevated risk. This concern is heightened by the CDC's (2020) observation that "travelers who spend a lot of time with local populations in the meningitis belt, especially during outbreaks of meningococcal disease, are more likely to get this disease."

Transmission

As noted above, Nm is an exclusively human pathogen. There is therefore no animal reservoir for Nm, and only humans can be infected with it. Transmission from one person to another can occur in a number of ways. According to the CDC (2019), the primary route of transmission is via carrier throat or respiratory secretions, making aerosols the key transmission medium. Regarding specific transmission formats, WHO (2018) is explicit that "smoking, close and prolonged contact — such as kissing, sneezing or coughing on someone, or living in close quarters with a carrier — facilitates the spread of" Nm. Large gatherings of people have accordingly been identified as a prominent transmission route.

It is also worth noting that, as WHO further observes, past studies have indicated that a large proportion of people are carriers of this pathogen. According to the CDC (2019), it is estimated that approximately 1 in every 10 persons carries the pathogen in his or her throat. In some instances — specifically in regions with a high disease burden — Nm can be present in 3 out of 10 persons without any presenting symptoms (Tommassen and Arenas, 2017). In certain cases, the body's defense systems are overwhelmed by Nm, at which point it spreads to the brain via the bloodstream.

Conclusion

When it comes to the control of Nm, the relevance of surveillance cannot be overstated. To a large extent, surveillance is meant not only to ensure that outbreaks are detected, but also to confirm them and assess various trends of incidence, as well as to develop disease burden estimates. On the preventive front, meningococcal vaccines have proven to be highly effective. Additionally, there is a clear need for individuals who have come into close contact with people likely to be infected with Nm to be placed on antibiotics in order to minimize their chances of infection — a strategy referred to in this paper as prophylaxis. Together, these approaches offer the most promising path toward reducing the global burden of Nm.

References

Centers for Disease Control and Prevention – CDC (2019). Meningococcal Disease: Causes and Spread to Others. https://www.cdc.gov/meningococcal/about/causes-transmission.html

Centers for Disease Control and Prevention – CDC (2020). Meningococcal Disease (Neisseria meningitidis). https://wwwnc.cdc.gov/travel/diseases/meningococcal-disease

Rouphael, N. G., & Stephens, D. S. (2012). Neisseria meningitidis: Biology, microbiology, and epidemiology. Methods in Molecular Biology, 799, 11–20.

Seib, K., & Peak, I. R. (2019). Neisseria meningitidis: Methods and Protocols. Springer New York.

Tommassen, J., & Arenas, J. (2017). Biological functions of the secretome of Neisseria meningitidis. Frontiers in Cellular and Infection Microbiology, 7(2), 25–36.

World Health Organization – WHO (2018). Meningococcal meningitis. https://www.who.int/news-room/fact-sheets/detail/meningococcal-meningitis