This paper examines the relationship between forced migration and infectious disease outbreaks. The analysis is based on a review of reports published in ProMED, a digital monitoring and reporting system for infectious diseases, to identify outbreak events involving forcibly displaced populations between 1996 and 2016.
The authors identified 128 outbreak events involving forcibly displaced populations in 48 countries, covering over 840,000 confirmed or suspected cases of infectious diseases. The low case counts relative to the global number of forcibly displaced people may reflect incomplete data or underreporting, despite the informal surveillance methodology that is used for ProMed.
- The number of ProMED infectious disease outbreak reports concerning forcibly displaced populations increased over the study period. Rates of outbreak events concerning forcibly displaced populations per total number of ProMED reports also increased. The mean incidence of outbreak events involving forcibly displaced populations increased from an average of 2.3 events per year during 1996 to 2002 to 5.7 during 2003 to 2009 to 11.4 events per year during 2010 to 2016.
- The study population was primarily identified as refugees (61 percent), followed by internally displaced persons (IDPs) (30 percent) and asylum seekers (9 percent).
- Outbreaks in forcibly displaced persons from ProMED included reports in refugee camps as well as refugee enclaves in cities or at borders.
- Infectious disease outbreaks occurred in many countries and cross-border regions. Most outbreaks were reported in Africa (52 percent), followed by Eastern Mediterranean (17 percent) and Southeast Asia (14 percent). Kenya experienced the largest number of distinct outbreaks (13) reported to ProMED, followed by Uganda (12).
- There are a wide range of infectious disease pathogens or syndromes that affect forcibly displaced populations. Outbreak events due to cholera, cutaneous leishmaniasis, dengue, hepatitis E, measles and poliomyelitis were the most common disease outbreaks afflicting displaced populations. Most reported cases were due to a large-scale cholera outbreak among IDPs affected by the 2010 Haiti earthquake (more than 520,000 cases) and a large-scale epidemic typhus outbreak in Burundi in 1998 (100,000 cases). Overall, most individual cholera outbreaks (23 outbreak events) occurred in the Africa region.
- A substantial number of outbreaks (30 percent) were related to vaccine-preventable disease cases (VPD). More than 16,000 VPD were identified, encompassing 39 outbreaks in 20 countries over the course of the study.
- Most outbreak events were due to acquisition of disease in the destination country. Of 128 reports, 63 percent (80) were due to local transmission in the destination country, 20 percent (25) were due to importation (acquired in the country of origin or during transit), and 18 percent (23) were unspecified based on manual review of the report. In cases of importation, 48 percent (12) events were attributed to incomplete vaccination of the displaced population. The reasons for interrupted vaccination when available, were cited as breakdown in local health infrastructure and mistrust of local medical care. These findings are consistent with prior studies that have demonstrated low risks of imported acute infectious diseases on host country epidemiology, while crowding associated with temporary resettlement increases the risk of outbreaks among displaced residents.
These findings underscore the importance of capturing displaced populations in surveillance systems for infectious diseases to enable rapid detection and response. The authors also highlight the need for:
- Public health investment and education about effective water, sanitation, and hygiene practices.
- Efforts by local and international agencies to expand coverage of vaccination programs for refugees and IDPs.
- Enhanced cross-border surveillance with targeted screening and treatment of infectious diseases.