Dataset Information

Armed conflict and population displacement as drivers of the evolution and dispersal of Mycobacterium tuberculosis.

ABSTRACT: The "Beijing" Mycobacterium tuberculosis (Mtb) lineage 2 (L2) is spreading globally and has been associated with accelerated disease progression and increased antibiotic resistance. Here we performed a phylodynamic reconstruction of one of the L2 sublineages, the central Asian clade (CAC), which has recently spread to western Europe. We find that recent historical events have contributed to the evolution and dispersal of the CAC. Our timing estimates indicate that the clade was likely introduced to Afghanistan during the 1979-1989 Soviet-Afghan war and spread further after population displacement in the wake of the American invasion in 2001. We also find that drug resistance mutations accumulated on a massive scale in Mtb isolates from former Soviet republics after the fall of the Soviet Union, a pattern that was not observed in CAC isolates from Afghanistan. Our results underscore the detrimental effects of political instability and population displacement on tuberculosis control and demonstrate the power of phylodynamic methods in exploring bacterial evolution in space and time.

SUBMITTER: Eldholm V

PROVIDER: S-EPMC5137683 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

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Armed conflict and population displacement as drivers of the evolution and dispersal of Mycobacterium tuberculosis.

Eldholm Vegard V Pettersson John H-O JH Brynildsrud Ola B OB Kitchen Andrew A Rasmussen Erik Michael EM Lillebaek Troels T Rønning Janne O JO Crudu Valeriu V Mengshoel Anne Torunn AT Debech Nadia N Alfsnes Kristian K Bohlin Jon J Pepperell Caitlin S CS Balloux Francois F

Proceedings of the National Academy of Sciences of the United States of America 20161121 48

The "Beijing" Mycobacterium tuberculosis (Mtb) lineage 2 (L2) is spreading globally and has been associated with accelerated disease progression and increased antibiotic resistance. Here we performed a phylodynamic reconstruction of one of the L2 sublineages, the central Asian clade (CAC), which has recently spread to western Europe. We find that recent historical events have contributed to the evolution and dispersal of the CAC. Our timing estimates indicate that the clade was likely introduced ...[more]

PMID: 27872285

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Project description:Background:South Sudan has endured decades of armed conflict, with the most recent in 2016. This has left the health system and infrastructure overstretched by a myriad of infectious diseases like tuberculosis. Our study aimed at quantitatively and qualitatively documenting TB dynamics and challenges with access to health care during a period of civil unrest in Wau. Materials & Methods:A cross sectional study was carried out between January and February 2016 at Wau Teaching Hospital (WTH). Sputum was randomly collected from 207 of the 1035?TB suspects and analyzed using Ziehl-Neelsen (ZN) and Fluorescent Microscopy (FM), Culture, Capilia MTBC Neo, and DST. The laboratory results and questionnaire metadata were used for descriptive statistics, logistic regression in R version 3.4.2. These results were presented along with results from a qualitative assessment of the situation at WTH. Results:Of 207?TB suspects, 39 (18.8%) were positive on FM with bacilli growth on culture, later confirmed as Mycobacterium tuberculosis complex. Only 5.4% of the cases were resistant to Isoniazid. Age; 20-45 OR?=?13 (95%CI?=?2.4-25.6, p?=?0.011),?>?46 OR?=?3 (95%CI?=?0.5-58, p?=?0.005) and raw milk consumption OR?=?2.2 (95%CI?=?0.37-42.48, p?=?0.005) were associated with being TB positive. The qualitative evaluation reveals that gunfights in the surroundings of Wau influenced the number of patients attending WTH, with some travelling up to 545?km to seek medical attention. Conclusion:We report a high prevalence of tuberculosis among patients who presented at WTH, with approximately 1 out of 5 individuals testing positive for tuberculosis. This is likely an underestimation given the challenges patients had to endure as they sought medical attention. Tuberculosis epidemiology is likely to be driven by individual and household factors, but further investigations are needed to fully understand the risk profile. The tools in use were adequate for TB diagnostics and we observed a remarkably low prevalence of drug resistance, a statistic that is worth preserving. We therefore call for action from all stakeholders.

Project description:BACKGROUND:A substantial portion of child deaths in Africa take place in countries with recent history of armed conflict and political instability. However, the extent to which armed conflict is an important cause of child mortality, especially in Africa, remains unknown. METHODS:We matched child survival with proximity to armed conflict using information in the Uppsala Conflict Data Program Georeferenced Events Dataset on the location and intensity of armed conflict from 1995 to 2015 together with the location, timing, and survival of infants younger than 1 year (primary outcome) in 35 African countries. We measured the increase in mortality risk for infants exposed to armed conflicts within 50 km in the year of birth and, to study conflicts' extended health risks, up to 250 km away and 10 years before birth. We also examined the effects of conflicts of varying intensity and chronicity (conflicts lasting several years), and effect heterogeneity by residence and sex of the child. We then estimated the number and portion of deaths of infants younger than 1 year related to conflict. FINDINGS:We identified 15?441 armed conflict events that led to 968?444 combat-related deaths and matched these data with 1·99 million births and 133?361 infant deaths (infant mortality of 67 deaths per 1000 births) between 1995 and 2015. A child born within 50 km of an armed conflict had a risk of dying before reaching age 1 year of 5·2 per 1000 births higher than being born in the same region during periods without conflict (95% CI 3·7-6·7; a 7·7% increase above baseline). This increased risk of dying ranged from a 3·0% increase for armed conflicts with one to four deaths to a 26·7% increase for armed conflicts with more than 1000 deaths. We find evidence of increased mortality risk from an armed conflict up to 100 km away, and for 8 years after conflicts, with cumulative increase in infant mortality two to four times higher than the contemporaneous increase. In the entire continent, the number of infant deaths related to conflict from 1995 to 2015 was between 3·2 and 3·6 times the number of direct deaths from armed conflicts. INTERPRETATION:Armed conflict substantially and persistently increases infant mortality in Africa, with effect sizes on a scale with malnutrition and several times greater than existing estimates of the mortality burden of conflict. The toll of conflict on children, who are presumably not combatants, underscores the indirect toll of conflict on civilian populations, and the importance of developing interventions to address child health in areas of conflict. FUNDING:The Doris Duke Charitable Foundation, and the Centre for Global Child Health at the Hospital for Sick Children.

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Armed conflict and population displacement as drivers of the evolution and dispersal of Mycobacterium tuberculosis.

Publications

Armed conflict and population displacement as drivers of the evolution and dispersal of Mycobacterium tuberculosis.

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