Mitigating measles outbreaks in West Africa post-Ebola

Abstract

The Ebola outbreak in 2014–2015 devastated the populations, economies and healthcare systems of Guinea, Liberia and Sierra Leone. With this devastation comes the impending threat of outbreaks of other infectious diseases like measles. Strategies for mitigating these risks must include both prevention, through vaccination, and case detection and management, focused on surveillance, diagnosis and appropriate clinical care and case management. With the high transmissibility of measles virus, small-scale reactive vaccinations will be essential to extinguish focal outbreaks, while national vaccination campaigns are needed to guarantee vaccination coverage targets are reached in the long term. Rapid and multifaceted strategies should carefully navigate challenges present in the wake of Ebola, while also taking advantage of current Ebola-related activities and international attention. Above all, resources and focus currently aimed at these countries must be utilized to build up the deficit in infrastructure and healthcare systems that contributed to the extent of the Ebola outbreak.

Keywords:

• Ebola
• measles
• outbreak
• surveillance
• vaccination

The ongoing Ebola outbreak in West Africa is one of the most devastating epidemics in recent history. Between March 2014 and June 2015, more than 27,500 cases and 11,200 deaths were reported in Sierra Leone, Liberia and Guinea, and the adverse impact on local economies and healthcare infrastructure has been substantial [1]. Although the epidemic appears to be receding, persistent detrimental effects on the health of affected communities are expected following disruptions to the healthcare system. The threat of vaccine-preventable diseases, particularly measles, is especially worrisome, as vaccination services were interrupted during the peak of the Ebola outbreak [2].

The healthcare crisis following the Ebola outbreak not only raises unique challenges but also opportunities. Throughout the epidemic, pockets of mistrust and fear of healthcare workers, resulting in violence in some cases, disrupted healthcare delivery beyond Ebola case finding and management [3]. Continued mistrust and misinformation will be a challenge for the delivery of therapeutic and preventive services including routine child vaccination. Ebola decimated the healthcare workforce in already overburdened healthcare systems; as of 11 July 2015, 509 deaths were reported among 875 healthcare workers with Ebola [1]. The focus of the international community is now on the three affected countries, and donors appear willing to invest in improving the healthcare systems in the region. This focus provides an opportunity to confront lingering deficiencies, including efforts to improve the health of women, children and newborns.

Measles vaccination

Measles has caused devastating outbreaks following humanitarian emergencies and natural disasters, and measles virus is circulating in Ebola-affected countries [4,5]. Vaccination is the most effective response to the threat of measles epidemics, and national and targeted vaccination campaigns have begun in Liberia, Guinea and Sierra Leone [5–7]. A rapid, flexible approach is needed to guarantee measles is quickly brought under control, including small-scale reactive vaccination campaigns, national supplementary immunization campaigns and strengthening of routine immunization activities.

Large national vaccination campaigns to supplement routine vaccination coverage are expensive and require significant planning. Hence, mass vaccination campaigns are not nimble enough to respond to outbreaks as they occur. Reactive campaigns, started after the number of cases has already begun to rise, have proven effective in some settings [8]. Such reactive campaigns are needed to prevent focal outbreaks already seen in the wake of the Ebola epidemic from growing into large, generalized epidemics involving multiple countries. Strategies to predict areas at risk of measles outbreaks by mapping vaccine coverage and immunity (e.g., Takahashi et al. 2015 [2]) may be used to target focal preemptive vaccination campaigns.

Supplemental immunization activities, particularly national vaccination campaigns, have long been a staple of measles control in countries with inadequately performing routine immunization programs in order to achieve and sustain high levels of population immunity. The three Ebola-affected countries were planning ‘follow-up’ measles vaccination campaigns before Ebola struck. The delay of these campaigns and disruption to routine vaccination services made the need for national mass vaccination campaigns more urgent. As of 17 August 2015, national measles vaccination campaigns have been conducted in Liberia and Sierra Leone, targeting 600,000 and 1.3 million children under 5 years, respectively [5,7]. Guinea plans to follow suit in October 2015 with a national campaign targeting 750,000 children [9].

These campaigns are being conducted under unusual circumstances, where the healthcare system is particularly stressed and with lingering mistrust of the public health community, including suspicion of Ebola vaccine trials [10]. As a consequence, measles vaccination campaigns may underperform and require well-planned community mobilization activities and rigorous monitoring and evaluation to ensure target populations are reached. Additional campaigns should be conducted in 1 or 2 years if coverage fails to meet the expectations. Furthermore, recent outbreaks in Malawi, Zambia and elsewhere raise concerns that future campaigns may need to target a broader age range (i.e., older children and young adults) to achieve high levels of population immunity and interrupt transmission [11].

Before the Ebola outbreak, countries in West Africa suffered from low rates of routine vaccination coverage. In 2013, coverage rates in Liberia, Sierra Leone and Guinea were estimated to be 74, 83 and 62%, respectively, which were significantly below the 90% national vaccination goal of the Measles and Rubella Initiative [12,13]. To provide sustained protection from measles, improved routine coverage with two doses of measles vaccine needs to be achieved and sustained.

Measles surveillance, diagnosis & case management

Surveillance

Early detection and reporting of measles cases will be among the main challenges in mitigating measles outbreaks. As a result of mistrust and misinformation, as well as fear of contracting Ebola, people are less likely to seek care for themselves or their family members [14]. One strategy to identify measles cases is through the ongoing door-to-door contact tracing for Ebola conducted by Médecins Sans Frontières and local health partners [15]. Active case detection of measles cases through home visits will allow for rapid, responsive targeted vaccination and can minimize diagnostic confusion with Ebola by alerting healthcare workers to local measles virus transmission.

Diagnosis

Accurate diagnosis of measles is paramount in Ebola-stricken areas. Missed cases mean missed opportunities to prevent further transmission. Potential confusion between Ebola and measles is relatively high as both are acute febrile illnesses. Misdiagnosis of malaria has already occurred in Ebola-affected countries [16]. Access to high-quality laboratories for confirmation of measles virus infection will be essential for accurate diagnosis and disease surveillance. To aid in correct diagnosis of measles cases, we need valid, inexpensive point-of-care tests to detect IgM antibodies to measles virus. While such tests have been developed and validated, their use in early outbreak detection has been limited [17].

Case management

Standard clinical care for suspected measles cases should be conducted with specific attention to the provision of two doses of vitamin A supplementation, antibiotics for secondary bacterial infections and nutritional support (as undernutrition has likely been exacerbated by the Ebola outbreak) [18,19]. It is not yet known if there are immunologic interactions between measles and Ebola viruses, but the immunosuppressive effects of measles virus could result in more severe Ebola virus infection, higher viral loads and increased mortality.

To separate measles and Ebola cases, particularly during large measles outbreaks, specific emergency treatment centers for measles cases may be essential. The consequences of nosocomial measles virus transmission in Ebola Treatment Centers are immense. Due to the high transmissibility of measles virus, a single case of measles in an Ebola Treatment Center would likely result in infection of every measles-susceptible Ebola patient before control measures could be implemented. Control would be extremely challenging due to the open nature of these centers and might be limited to restricting admission of new Ebola patients. If large measles outbreaks were to occur, introduction of Ebola virus into measles wards could spark a resurgence of the Ebola epidemic. Also, with the persistent mistrust and misinformation, an event exposing measles cases to Ebola virus or Ebola cases to measles virus could adversely impact control efforts, fuel suspicion of the healthcare system and result in fewer people with Ebola or measles seeking care.

The overall impact of Ebola & long-term improvement

While the immediate threat of measles in West Africa has garnered recent media attention, coverage for other vaccine-preventable diseases such as pertussis and the control of other communicable diseases such as malaria have been diminished by the Ebola outbreak and its impact on health-seeking behaviors, healthcare workers and the healthcare system [20]. A recent study found that an estimated 74,000 fewer suspect malaria cases were seen and treated at public health facilities in 2014 in Guinea alone. Extrapolated across all three countries for the duration of the epidemic, this could equate to hundreds of thousands of malaria cases going untreated [20]. Efforts to bolster measles vaccination and control transmission should be combined with other preventive efforts, such as strengthening routine immunization services, distribution of insecticide-treated bed nets and administration of vitamin A. Active case detection for Ebola cases and contact tracing can be used to detect outbreaks of other infectious diseases, including measles, pertussis and malaria.

The scale and devastation of the 2014–2015 Ebola outbreak was not a result of bad luck – it was a confluence of poor healthcare infrastructure, lack of trained healthcare workers, mistrust and misinformation, and global inaction. While it is essential in the short term that efforts are made to prevent impending outbreaks of measles and other infectious diseases, we must invest in sustainable improvements in the healthcare systems in the affected countries, lest we allow history to repeat itself.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.