More bad news for Yemen this week. Already facing a massive cholera epidemic and a humanitarian crisis associated with the escalating civil war—the subject of two previous Outbreak Thursday posts—Yemen is now reporting more than 2,000 cases of meningitis for 2017, nearly as many cases as was reported in all of 2016. This latest rise in meningitis cases comes as the WHO reports that cholera cases have exceeded 470,000 (as of August 6), with approximately 30,000 additional cases identified each week.

Meningitis is an acute inflammatory disease of the meninges—the protective covering of the brain and spinal cord. Various pathogens, including bacteria, viruses, fungi and parasites, can be responsible for the inflammation, and identifying the specific cause is important to delivering the appropriate treatment. For bacterial meningitis, according to one source, “Microbiological identification and susceptibility testing of the causative agent are key determinants of successful antibiotic therapy,” particularly in a world of growing antibiotic resistance.

While the drivers of this outbreak likely mirror those of the cholera epidemic, there remain many questions to be answered about the increase in meningitis.

What type of meningitis is affecting Yemen?

It is unclear at this point which—or how many—of these pathogens are driving the increase in meningitis in Yemen. Meningitis is endemic in many Middle Eastern countries, including Yemen, and Neisseria meningitidis serogroup A is the most commonly reported etiologic agent in the region. Incidence rates in Yemen vary dramatically—from 72.42 per 100,000 people in 1988 to less than 5 per 100,000 from 2003 to 2005 (although reporting is sporadic). In the current outbreak, 920 cerebrospinal fluid (CSF) samples have been sent for Gram stain and culture: 5 tested positive for Streptococcus Pneumoniae, 2 for N. meningitidis, and 11 for other bacteria. According to a WHO report, it is unknown why so few of the CSF samples tested positive for bacterial meningitis, but could be due to self-medication with antibiotics, poor sample collection and handling, and limited access to laboratories capable of conducting the proper tests. However, while the report states that samples have been tested by gram stain and culture, it is unclear at this time whether they have also been tested for non-bacterial pathogens. Additionally, while nearly a thousand CSF specimens have been sent for testing, it is yet unclear how the remaining cases were diagnosed.

What is the affected population?

Several studies in Africa’s meningitis belt have analyzed the spread of infectious disease, including meningitis, in refugee camps. These populations face similar challenges as those currently impacting Yemen. In fact, one study of a Rwandan refugee camp in Zaire (1994) indicated that “Manslaughter, cholera, and bacillary dysentery were the initial and leading lethal epidemics, followed chronologically by malnutrition, meningitis, and malaria,” which, with the exception of malaria, sounds eerily similar to what is going on in Yemen. One study that analyzed reported neurological disease in refugee camps across 19 countries in Africa, the Eastern Mediterranean, and Southeast Asia noted that meningitis was detected in most countries, and at least one country in each region, including Yemen. Another study found that, while meningitis in endemic areas predominantly affects young children, outbreaks in populations like refugee camps tend to affect older children and adults (15-29 years). In contrast, nearly ⅔ of the cases in Yemen have been reported in children under the age of 5. Routine immunizations in Yemen include several meningitis-associated pathogens; however, the ongoing conflict has likely impacted the coverage rate for children.

What is exacerbating the problem?

As is has been widely discussed in other reports, the ongoing civil war in Yemen has greatly undermined the ability to provide healthcare services. A human rights NGO recently attributed 10,000 preventable deaths in Yemen to the closing of the airport in Sanaa, which significantly hinders the ability to receive humanitarian aid and seek advanced clinical care outside of Yemen. Additionally, food insecurity has led to a rapidly growing nutrition crisis throughout the country, resulting in nearly two million acutely malnourished Yemeni children. UN Development Program Director, Auke Lootsma, called the food security crisis in Yemen a “man-made disaster” that stems from decades of poverty and conflict. Those who are already battling diseases are more likely to be malnourished, which, in turn, makes them even more susceptible to diseases. This dangerous cycle has perpetuated the spread of disease in Yemen by creating the ideal breeding ground for various pathogens such as those that cause meningitis.

Imported meningitis-associated pathogens could also be contributing to the increase in Yemen. As discussed in a previous post about outbreak preparedness for the Hajj, imported meningitis has been linked to outbreaks at mass gathering events that draw participants from around the world and place them in prolonged close contact with one another. Despite the ongoing conflict, refugees from Africa are being smuggled into Yemen in hopes of gaining access to wealthier Middle Eastern countries. Because meningitis is highly prevalent in many parts of sub-Saharan Africa, this provides further opportunity for the importation of meningitis-associated pathogens into Yemen. As discussed above, the conditions in refugee camps (eg, prolonged close contact, poor hygiene and sanitation) can facilitate meningitis outbreaks. The WHO reports that meningitis cases have been reported in nearly all governorates in Yemen, but it is unclear at this time if outbreaks are localized to specific populations, such as refugee camps, or if it more widely spread throughout the country.

What is being done or can be done?

Bacterial meningitis, already endemic in Yemen, can be prevented through vaccination. Several studies in African refugee camps suggest that mass vaccination campaigns can be effective in responding to outbreaks; however, the effect can be limited if the campaign is not initiated early in the outbreak. Additionally, active case identification and treatment can substantially reduce case fatality rates for outbreaks. Similar to the cholera epidemic, however, improvements in the healthcare infrastructure and access for humanitarian aid will be critical to controlling any infectious disease event in Yemen.


Outbreak Observatory aims to collect information on challenges and solutions associated with outbreak response and share it broadly in near-real time to allow others to learn from these experiences in order to improve global outbreak response capabilities.


Photo courtesy of CDC/Medical Illustrator