Genomic epidemiology reveals multidrug resistant plasmid spread between Vibrio cholerae lineages in Yemen.

Since 2016, Yemen has been experiencing the largest cholera outbreak in modern history. Multidrug resistance (MDR) emerged among Vibrio cholerae isolates from cholera patients in 2018. Here, to characterize circulating genotypes, we analysed 260 isolates sampled in Yemen between 2018 and 2019. Eighty-four percent of V. cholerae isolates were serogroup O1 belonging to the seventh pandemic El Tor (7PET) lineage, sub-lineage T13, whereas 16% were non-toxigenic, from divergent non-7PET lineages. Treatment of severe cholera with macrolides between 2016 and 2019 coincided with the emergence and dominance of T13 subclones carrying an incompatibility type C (IncC) plasmid harbouring an MDR pseudo-compound transposon. MDR plasmid detection also in endemic non-7PET V. cholerae lineages suggested genetic exchange with 7PET epidemic strains. Stable co-occurrence of the IncC plasmid with the SXT family of integrative and conjugative element in the 7PET background has major implications for cholera control, highlighting the importance of genomic epidemiological surveillance to limit MDR spread.

Circulating vaccine derived polio virus type 1 outbreak, Saadah governorate, Yemen, 2020.

BACKGROUND: Yemen has faced one of the worst humanitarian crises in the world since the start of the war in 2015. In 2020; 30 Vaccine Derived Polio Virus type 1 (VDPV1) isolates were detected in Saadah governorate. The aims are to characterize the outbreak and address the gaps predisposing the emergence and circulation of VDPV1 in Saadah governorate, Yemen. METHOD: A retrospective descriptive study of confirmed cases of VDPV1 between January and December 2020 was performed. Surveillance staff collected data from patient cases, contacts, as well as stool specimens that shipped to WHO accredited polio labs. Data of population immunity was also reviewed. The difference in days between the date of sample collection, shipment, and receiving lab result was used to calculate the average of delayed days for lab confirmation. RESULTS: From January to December 2020, a total of 114 cases of acute flaccid paralysis (AFP) were reported from 87% (13/15) districts, and cVDPV1 was confirmed among 26% (30) AFP cases. 75% (21) were < 5 years, 73% (20) had zero doses of Oral Polio Vaccine (OPV). The first confirmed case (3%) was from Saadah city, with paralysis onset at the end of January 2020 followed by 5 cases (17%) in March from another four districts, 8 cases (27%) in April, and 13 (43%) up to December 2020 were from the same five districts in addition to 3 (10%) form three new districts. The lab confirmation was received after an average of 126 days (71-196) from sample collection. The isolates differ from the Sabin 1 type by 17- 30 VP1 nucleotides (nt) and were linked to VDPV1 with 13 (nt) divergence that isolated in July 2020 from stool specimens collected before one year from contacts of an inadequate AFP case reported from Sahar district. CONCLUSION: The new emerging VDPV1 was retrospectively confirmed after one year of sample collection from Sahar district. Delayed lab confirmation, as well as the response and low immunization profile of children against polio, were the main predisposing factors for cVDPV1 outbreak. This outbreak highlights the need to maintain regular biweekly shipments to referral polio labs in the short-term, and the exploration of other options in the longer-term to enable the Yemen National Lab to fully process national samples itself.

Influenza circulating viruses, positivity rate and risk factors for influenza associated severe acute respiratory infection during 2018/2019 winter season, Yemen.

BACKGROUND: The burden of seasonal influenza in conflict counties is exacerbated due to limited resource and collapse of health system. During 2018 /2019 season, two-fold increase in the incidence of influenza was reported in Yemen with 22% case fatality of severe acute respiratory infection (SARI). The aims are to analyze the influenza circulating viruses, positivity rate and risk factors for hospitalizing influenza associated-SARI. METHODOLOGY: We used a retrospective analytical study based on surveillance data. All reported patients during 2018/2019 season, fulfilling the WHO cases definition for SARI or influenza like illness (ILI), and had laboratory result from the National Laboratory were included. Influenza positivity rate was calculated, all SARI and ILI patients with positive influenza were included for further analysis by univariate and multivariate binary logistic regression. Crude and adjusted Odds ratio (AOR), 95% confidence interval and P-value < 0.05 were used for statistically significant. RESULTS: Out of 2186 patients enrolled, 768 patients were tested for influenza viruses,: 19% were children < 15 years, 15% were ≥ 65 years, 69% males and 18% had co-morbidity with chronic diseases. Patients with SARI were 37% and 63% were ILI patients. Influenza viruses were detected in 411 (53.5%), 68% were influenza A subtype (H1N1)pdm09, 27% influenza B and 5% was influenza A not subtyped. The influenza positivity was significantly higher in SARI compared to ILI for patients < 15 years (95% vs, 66%, p < 0.001), and patients ≥ 65 years (83% vs. 56%, p < 0.002), respectively. The highest positivity for influenza type A and B reached 44% and 33% for patients ≥ 65 years and < 15 years, respectively. The risk factors for influenza-associated SARI in multivariate analysis included age < 5 [AOR 2.8] and ≥ 65 years old [AOR 3.1] compared to age 5- < 25 years, diabetes [AOR 4.7], heart diseases [AOR 3.1] and chronic respiratory diseases [AOR 5.0]. CONCLUSION: The influenza positivity during 2018/2019 winter season was high in Yemen and varied by age distribution. Influenza subtype A (H1N1) pdm09 was the predominant and co circulated with influenza B. An influenza vaccination program for the risk group is necessary. Strengthening lab capacity to detect respiratory pathogens and further prospective study for more comprehensive picture are recommended.

Field Epidemiology Training Program Response to COVID-19 During a Conflict: Experience From Yemen.

COVID-19 pandemic has underscored the need for a well-trained public health workforce to save lives through timely outbreaks detection and response. In Yemen, a country that is entering its seventh year of a protracted war, the ongoing conflict severely limited the country's capacity to implement effective preparedness and response measures to outbreaks including COVID-19. There are growing concerns that the virus may be circulating within communities undetected and unmitigated especially as underreporting continues in some areas of the country due to a lack of testing facilities, delays in seeking treatment, stigma, difficulty accessing treatment centers, the perceived risks of seeking care or for political issues. The Yemen Field Epidemiology Training Program (FETP) was launched in 2011 to address the shortage of a skilled public health workforce, with the objective of strengthening capacity in field epidemiology. Thus, events of public health importance can be detected and investigated in a timely and effective manner. During the COVID-19 pandemic, the Yemen FETP's response has been instrumental through participating in country-level coordination, planning, monitoring, and developing guidelines/standard operating procedures and strengthening surveillance capacities, outbreak investigations, contact tracing, case management, infection prevention, and control, risk communication, and research. As the third wave is circulating with a steeper upward curve than the previous ones with possible new variants, the country will not be able to deal with a surge of cases as secondary care is extremely crippled. Since COVID-19 prevention and control are the only option available to reduce its grave impact on morbidity and mortality, health partners should support the Yemen FETP to strengthen the health system's response to future epidemics. One important lesson learned from the COVID-19 pandemic, especially in the Yemen context and applicable to developing and war-torn countries, is that access to outside experts becomes limited, therefore, it is crucial to invest in building national expertise to provide timely, cost-effective, and sustainable services that are culturally appropriate. It is also essential to build such expertise at the governorate and district levels, as they are normally the first respondents, and to provide them with the necessary tools for immediate response in order to overcome the disastrous delays.

Performance of the Neonatal Tetanus Surveillance System (NTSS) in Sana'a, Yemen: Evaluation Study.

BACKGROUND: The Neonatal Tetanus Surveillance System (NTSS) in Yemen was established in 2009 to identify high-risk areas, determine trends, and evaluate elimination activities. Since its launch, the NTSS had never been evaluated. OBJECTIVE: This study aimed to assess the performance of NTSS and determine its strengths and weaknesses to recommend improvements. METHODS: The US Centers for Disease Control and Prevention (CDC) guidelines were used for evaluating the NTSS. Stakeholders at the central, district, and facility levels were interviewed to rate the attributes of the NTSS. The percentage scores for attributes were ranked as poor (<60%), average (≥60% to <80%) and good (≥80%). RESULTS: The overall usefulness score percentage was 38%, which indicates a poor performance. The performance of the NTSS was rated as average on flexibility (score percent: 68%) and acceptability (score percent: 64%) attributes and poor on stability (score percentage: 33%), simplicity (score percentage: 57%), and representativeness (score percentage: 39%) attributes. About 65% of investigation forms were completed within 48 hours of notification date. Data quality was poor, as 41% of the core variables were missing. CONCLUSIONS: The overall performance of the NTSS was poor. Most of the system attributes require improvement, including stability, simplicity, quality of data, and completeness of investigation. To improve the performance of NTSS, the following are recommended: capacity building of staff (focal points), strengthening NTSS through technical support and government funding to ensure its sustainability, establishing electronic investigation forms for improving the system data quality, and expansion of NTSS coverage to include all private health care facilities.

Ongoing diphtheria outbreak in Yemen: a cross-sectional and genomic epidemiology study.

BACKGROUND: An outbreak of diphtheria, declared in Yemen in October, 2017, is ongoing. We did a cross-sectional study to investigate the epidemiological, clinical, and microbiological features of the outbreak. METHODS: Probable cases of diphtheria that were defined clinically and recorded through a weekly electronic diseases early warning system (from 2017, week 22, to 2020, week 17) were used to identify trends of the outbreak (we divided the epidemic into three time periods: May 29, 2017, to June 10, 2018; June 11, 2018, to June 3, 2019; and June 4, 2019, to April 26, 2020). We used the line list of diphtheria reports for governorate-level descriptions. Vaccination coverage was estimated using the 2017 and 2018 annual reports by the national Expanded Programme on Immunization. To confirm cases biologically, Corynebacterium diphtheriae was isolated and identified from throat swabs using standard microbiological culture and identification procedures. We assessed differences in the temporal and geographical distributions of cases, including between different age groups. For in-depth microbiological analysis, tox gene and species-specific rpoB real-time PCR, Illumina genomic sequencing, antimicrobial susceptibility analysis (disk diffusion, E-test), and the Elek diphtheria toxin production test were done on confirmed cases. We used genomic data for phylogenetic analyses and to estimate the nucleotide substitution rate. FINDINGS: The Yemen diphtheria outbreak affected almost all governorates (provinces), with 5701 probable cases and 330 deaths recorded up to April 26, 2020. We collected clinical data for 888 probable cases with throat swab samples referred for biological confirmation, and genomic data for 42 positive cases, corresponding to 43 isolates (two isolates from one culture were included due to distinct colony morphologies). The median age of patients was 12 years (range 0·2-80). The proportion of cases in children aged 0-4 years was reduced during the second time period, after a vaccination campaign, compared with the first period (19% [95% CI 18-21] in the first period vs 14% [12-15] in the second period, p<0·0001). Among 43 tested isolates, 39 (91%) produced the diphtheria toxin and two had low level (0·25 mg/L) antimicrobial resistance to penicillin. We identified six C diphtheriae phylogenetic sublineages, four of which are genetically related to isolates from Saudi Arabia, Eritrea, and Somalia. Inter-sublineage genomic variations in genes associated with antimicrobial resistance, iron acquisition, and adhesion were observed. The predominant sublineage (30 [70%] of 43 isolates) was resistant to trimethoprim and was associated with unique genomic features, more frequent neck swelling (p=0·0029) and a younger age of patients (p=0·060) compared with the other sublineages. Its evolutionary rate was estimated at 1·67 × 10-6 substitutions per site per year, placing its most recent common ancestor in 2015, and indicating silent circulation of C diphtheriae in Yemen before the outbreak was declared. INTERPRETATION: In the Yemen outbreak, C diphtheriae shows high phylogenetic, genomic, and phenotypic variation. Laboratory capacity and real-time microbiological monitoring of diphtheria outbreaks need to be scaled up to inform case management and transmission control of diphtheria. Catch-up vaccination might have provided some protection to the targeted population (children aged 0-4 years). FUNDING: National Centre of the Public Health Laboratories (Yemen), Institut Pasteur, and the French Government Investissement d'Avenir Programme. TRANSLATION: For the Arabic translation of the abstract see Supplementary Materials section.

The Acute Flaccid Paralysis (AFP) Surveillance System in Yemen, 2010-2015: Descriptive Study Based on Secondary Data Analysis.

BACKGROUND: Acute flaccid paralysis (AFP) surveillance is an essential strategy for poliovirus eradication. OBJECTIVE: This study aimed to evaluate the performance of the AFP surveillance system in Yemen from 2010 to 2015, identify components that require strengthening, and compare the indicators by year and governorates. METHODS: This descriptive study was based on secondary analysis of AFP surveillance data reported during 2010-2015 from all Yemeni governorates. The World Health Organization (WHO) minimum performance standards were used to evaluate the performance of the AFP surveillance system. RESULTS: A total of 3019 AFP cases were reported between January 2010 and December 2015. At the national level, AFP surveillance achieved WHO targets throughout the evaluating period for the nonpolio AFP rate of cases per 100,000 members of the population younger than 15 years of age, proportion of AFP cases reported within 7 days, proportion of AFP cases investigated within 48 hours of notification, proportion of AFP cases with two adequate stool specimens, and proportion of stool specimens from which nonpolio enterovirus was isolated. However, the proportion of specimens that arrived at the central level within 3 days of the first sample collection and the proportion of stool specimens with results sent from the reference laboratory within 28 days of receipt did not reach targets in 2011 and 2015, respectively. CONCLUSIONS: The AFP surveillance system in Yemen has met most of the WHO indicator levels. Nevertheless, the evaluation showed areas of weakness regarding the arrival of specimens at the central level within 3 days of the first sample collection and delays in processing of the results and submitting feedback by the laboratory. Therefore, there is a need to strengthen the follow-up of specimens submitted to the laboratory.