Targeting strategies of antenatal balanced energy and protein supplementation in Addis Ababa, Ethiopia: study protocol for a randomized effectiveness study

BACKGROUND

Antenatal balanced energy and protein (BEP) supplements have well-documented benefits for pregnancy outcomes. However, considerable practical gaps remain in the effective and cost-effective delivery of antenatal BEP supplements at scale in low- and middle-income countries.

METHODS

A randomized effectiveness study will be conducted in two sub-cities of Addis Ababa, Ethiopia, to evaluate the effectiveness, cost-effectiveness, and implementation of different targeting strategies of antenatal BEP supplements. Pregnant women aged 18 to 49, with a gestational age of 24 weeks or less, and attending antenatal visits in one of the nine study health facilities are eligible for enrollment. In six of the health facilities, participants will be randomized to one of three study arms: control (Arm 1), targeted BEP provision based on baseline nutritional status (Arm 2), and targeted BEP supplementation based on baseline nutritional status and monthly gestational weight gain (GWG) monitoring (Arm 3). In the remaining three facilities, participants will be assigned to universal BEP provision (Arm 4). Participants in Arms 2 and 3 will receive BEP supplements if they have undernutrition at enrollment, as defined by a baseline body mass index less than 18.5 kg/m2 or mid-upper arm circumference less than 23 cm. In Arm 3, in addition to targeting based on baseline undernutrition, regular weight measurements will be used to identify insufficient GWG and inform the initiation of additional BEP supplements. Participants in Arm 4 will receive BEP supplements until the end of pregnancy, regardless of baseline nutritional status or GWG. All participants will receive standard antenatal care, including iron and folic acid supplementation. A total of 5400 pregnant women will be enrolled, with 1350 participants in each arm. Participants will be followed up monthly during their visits to the antenatal facilities until delivery. Maternal and infant health status will be evaluated within 72 h after delivery and at 6 weeks postpartum. The effectiveness and cost-effectiveness of the different BEP targeting strategies in preventing adverse pregnancy outcomes will be compared across arms. Qualitative data will be analyzed to assess the feasibility, acceptability, and implementation of different supplementation strategies.

DISCUSSION

This study will inform global recommendations and operational guidelines for the effective and cost-effective delivery of antenatal BEP supplements. The targeted approaches have the potential for broader scale-up in Ethiopia and other low-resource settings with a high burden of undernutrition among pregnant women.

TRIAL REGISTRATION

ClinicalTrials.gov registration number: NCT06125860. Registered November 9, 2023.

'God protects us from death through faith and science': a qualitative study on the role of faith leaders in combating the COVID-19 pandemic and in building COVID-19 vaccine trust in Addis Ababa, Ethiopia

OBJECTIVE

This study explored faith leaders' perspectives on the COVID-19 vaccine and their role in building COVID-19 vaccine trust in Addis Ababa, Ethiopia.

DESIGN

A qualitative study with in-depth interviews and thematic analysis was conducted.

PARTICIPANTS

Twenty-one faith leaders from the seven religious groups represented in the Inter-Religious Council of Ethiopia participated in the study.

SETTING

The study was conducted in Addis Ababa, Ethiopia.

RESULTS

The thematic analysis revealed three themes. First, faith leaders were aware of the risks of the COVID-19 pandemic, although most ascribed a spiritual meaning to the advent of the pandemic. The pandemic seriously affected the faith communities, inflicting financial losses. Second, faith leaders were essential allies during the pandemic by effectively collaborating with government and health professionals in COVID-19 prevention activities and public health interventions using spiritual reasoning. They were actively informing the community about the importance of the COVID-19 vaccine, where many faith leaders were publicly vaccinated to build trust in the vaccine and act as role models. Third, despite this, they faced multiple questions from the congregation about the vaccine, including rumours.

CONCLUSIONS

This research showed that faith leaders played crucial roles in encouraging vaccine use but were limited in their persuasion power because of intense rumours and misinformation. Empowering faith leaders with the latest vaccine evidence needs to be prioritised in the future.

Facilitators and barriers to implementing chest radiography in tuberculosis systematic screening of clinically high-risk groups in Ethiopia: A qualitative study

Background

Chest X-ray has been included in national tuberculosis screening algorithms as a sensitive tuberculosis screening tool among high-risk groups. However, the implementation was influenced by multiple factors. We aimed to explore facilitators and barriers to implementing chest X-ray in systematic tuberculosis screening of clinically high-risk groups in Addis Ababa, Ethiopia.

Methods

We conducted face-to-face, in-depth interviews with purposively selected participants at tertiary-level hospitals and a tuberculosis program coordinator at the Ethiopian Ministry of Health, who coordinates chest X-ray-guided systematic tuberculosis screening. A framework analysis was conducted using the consolidated framework for implementation research.

Results

We identified 11 constructs that influenced the implementation of the chest X-ray intervention. Facilitators included the relative sensitivity of chest X-ray over symptom-based screening, its potential integration into existing systems, technological advancements in the area, policies and laws supporting the screening intervention, and the quality of the evidence of the screening intervention. Barriers included implementation complexity, high costs of the intervention, knowledge gaps among healthcare providers, training gaps, low priority for chest X-ray screening at the healthcare facility level, and a lack of external support from the Ministry of Health and stakeholders.

Conclusion

This study identified contextual factors that influence the implementation of chest X-ray guided systematic tuberculosis screening among clinically high-risk groups that healthcare facilities and health ministries may use for decision-making. Addressing the barriers identified by the study would help to improve the implementation of chest X-rays for improved tuberculosis case detection and prompt treatment in clinically high-risk groups.

Network analysis of mental health problems among adults in Addis Ababa, Ethiopia: a community-based study during the COVID-19 pandemic

OBJECTIVE

COVID-19 has negatively impacted mental health of adults globally with increased rates of psychiatric comorbidities. However, network analysis studies to examine comorbidities and correlations between symptoms of different mental disorders are uncommon in low-income countries. This study aimed to investigate the network structure of depression, anxiety and perceived stress among adults in Addis Ababa and identify the most central and bridge symptoms within the depressive-anxiety-perceived symptoms network model.

DESIGN

Community-based cross-sectional study.

SETTING

This study was carried out on a sample of the general population in Addis Ababa during the first year of the COVID-19 pandemic. A total of 1127 participants were included in this study, of which 747 (66.3%) were females, and the mean age was 36 years.

PRIMARY AND SECONDARY OUTCOME MEASURES

Symptoms of depression, anxiety and stress were measured using the Patient Health Questionnaire, Generalized Anxiety Disorder Scale and the Perceived Stress Scale, respectively.Network analysis was conducted to investigate the network structure. The centrality index expected influence (EI) and bridge EI (1-step) were applied to determine the central and bridge symptoms. Case-dropping procedure was used to examine the network stability.

RESULT

The sad mood (EI=1.52) was the most central and bridge symptom in the depression, anxiety and perceived stress network model. Irritability (bridge EI=1.12) and nervousness and stressed (bridge EI=1.33) also served as bridge symptoms. The strongest edge in the network was between nervousness and uncontrollable worry (weight=0.36) in the anxiety community. The network had good stability and accuracy. The network structure was invariant by gender and age based on the network structure invariance test.

CONCLUSIONS

In this study, the sad mood was the core and bridge symptom. This and the other central and bridge symptoms identified in the study should be targeted to prevent mental health disorders and comorbidities among adults.

Determinants of COVID-19 vaccine readiness and hesitancy among adults in sub-Saharan Africa

There is very limited data on the extent and determinants of COVID-19 vaccine hesitancy among adults living in sub-Saharan Africa since the global roll-out of vaccines began in 2021. This multi-country survey sought to investigate COVID-19 vaccine hesitancy and other predictors of readiness to get vaccinated. We conducted surveys among adults residing in nine urban and rural areas in Burkina Faso, Ethiopia, Ghana, Nigeria, and Tanzania in late 2021. Log binomial regression models were used to identify prevalence and factors associated with vaccine hesitancy and beliefs around COVID-19 misinformation. We completed a total of 2,833 interviews. Among all respondents, 9% had never heard of a COVID-19 vaccine, 12% had been vaccinated, and 20% knew someone else who had been vaccinated. The prevalence of vaccine hesitancy varied by country (Ethiopia 29%, Burkina Faso 33%, Nigeria 34%, Ghana 42%, Tanzania 65%), but not by rural or urban context. People who did not think the vaccine was safe or effective, or who were unsure about it, were more likely to be vaccine hesitant. Those who reported they did not have a trusted source of information about the vaccine (aPR: 1.25, 95% CI: 1.18,1.31) and those who thought the vaccine would not be made available to them within the year were more likely to be vaccine hesitant. Women were more likely to be vaccine hesitant (aPR: 1.31, 95% CI: 1.19,1.43) and believe COVID-19 falsehoods (aPR: 1.05, 95% CI: 1.02,1.08). The most commonly believed falsehoods were that the vaccine was developed too fast and that there was not enough information about whether the vaccine was effective or not. Educational campaigns targeted at misinformation and tailored to suit each country are recommended to build trust in COVID-19 vaccines and reduce hesitancy.

The COVID-19 pandemic and its impacts on diet quality and food prices in sub-Saharan Africa

BACKGROUND

Sub-Saharan Africa faces prolonged COVID-19 related impacts on economic activity, livelihoods and nutrition, with recovery slowed down by lagging vaccination progress.

OBJECTIVE

This study investigated the economic impacts of COVID-19 on food prices, consumption and dietary quality in Burkina Faso, Ethiopia, Ghana, Nigeria, and Tanzania.

METHODS

We conducted a repeated cross-sectional study using a mobile platform to collect data from July-December, 2021 (round 2). We assessed participants' dietary intake of 20 food groups over the previous seven days and computed the primary outcome, the Prime Diet Quality Score (PDQS), and Dietary Diversity Score (DDS), with higher scores indicating better quality diets. We used generalized estimating equation (GEE) linear regression models to assess factors associated with diet quality during COVID-19.

RESULTS

Most of the respondents were male and the mean age was 42.4 (±12.5) years. Mean PDQS (±SD) was low at 19.4(±3.8), out of a maximum score of 40 in this study. Respondents (80%) reported higher than expected prices for all food groups. Secondary education or higher (estimate: 0.73, 95% CI: 0.32, 1.15), medium wealth status (estimate: 0.48, 95% CI: 0.14, 0.81), and older age were associated with higher PDQS. Farmers and casual laborers (estimate: -0.60, 95% CI: -1.11, -0.09), lower crop production (estimate: -0.87, 95% CI: -1.28, -0.46) and not engaged in farming (estimate: -1.38, 95% CI: -1.74, -1.02) were associated with lower PDQS.

CONCLUSION

Higher food prices and lower diet quality persisted during the COVID-19 pandemic. Economic and social vulnerability and reliance on markets (and lower agriculture production) were negatively associated with diet quality. Although recovery was evident, consumption of healthy diets remained low. Systematic efforts to address the underlying causes of poor diet quality through transforming food system value chains, and mitigation measures, including social protection programs and national policies are critical.

Dietary Perspectives and Practices during Pregnancy in Rural Amhara Region of Ethiopia: An Exploratory Qualitative Study

Background

Nutrition during pregnancy has lifelong impacts on the mother and fetus. In Ethiopia, nearly a third of pregnant women experience undernutrition. When designing nutrition interventions during pregnancy, it is important to understand existing dietary perspectives and practices in local communities.

Objectives

To explore the processes that shape dietary perspectives and practices during pregnancy in rural West Gojjam and South Gondar Zones of the Amhara region in Ethiopia.

Methods

From October to November 2018, we conducted 40 in-depth interviews with pregnant women (n = 16), family members (n = 12), and healthcare providers (n = 12) using a semistructured interview guide. Interviews were conducted in Amharic, transcribed in Amharic, and translated into English. We used a thematic analysis approach to organize data per the predefined topic areas and identify emerging themes, as well as barriers and enablers to healthy nutrition during pregnancy.

Results

Pregnant women and their family members recognized the benefits of a diversified diet to promote the health of the mother and the fetus. However, participants reported low dietary diversity because of limited access to nutritious foods and particular perspectives on food restrictions during pregnancy. The common practice of religious fasting also limited pregnant women's dietary intake. Women reported restricting their food intake in later pregnancy because of loss of appetite, as well as concerns about having a large infant, which might complicate delivery. Intake of locally made alcoholic drinks (Tella) was reported among pregnant women because participants thought it had low levels of alcohol that would not harm the fetus.

Conclusions

Although participants understood the importance of a healthy and diverse diet in pregnancy, we identified several barriers and perspectives regarding nutrition during pregnancy. Low income and lack of access to diverse foods, particularly in certain seasons, religious fasting, intentional food restrictions to limit the size of the infant, and alcohol use were commonly reported. Locally appropriate counseling and interventions should be developed, with an emphasis on increasing access to and consumption of diverse foods. Curr Dev Nutr 2023;x:xx.

Vulnerable newborn types: analysis of subnational, population-based birth cohorts for 541 285 live births in 23 countries, 2000-2021

OBJECTIVE

To examine prevalence of novel newborn types among 541 285 live births in 23 countries from 2000 to 2021.

DESIGN

Descriptive multi-country secondary data analysis.

SETTING

Subnational, population-based birth cohort studies (n = 45) in 23 low- and middle-income countries (LMICs) spanning 2000-2021.

POPULATION

Liveborn infants.

METHODS

Subnational, population-based studies with high-quality birth outcome data from LMICs were invited to join the Vulnerable Newborn Measurement Collaboration. We defined distinct newborn types using gestational age (preterm [PT], term [T]), birthweight for gestational age using INTERGROWTH-21st standards (small for gestational age [SGA], appropriate for gestational age [AGA] or large for gestational age [LGA]), and birthweight (low birthweight, LBW [<2500 g], nonLBW) as ten types (using all three outcomes), six types (by excluding the birthweight categorisation), and four types (by collapsing the AGA and LGA categories). We defined small types as those with at least one classification of LBW, PT or SGA. We presented study characteristics, participant characteristics, data missingness, and prevalence of newborn types by region and study.

RESULTS

Among 541 285 live births, 476 939 (88.1%) had non-missing and plausible values for gestational age, birthweight and sex required to construct the newborn types. The median prevalences of ten types across studies were T+AGA+nonLBW (58.0%), T+LGA+nonLBW (3.3%), T+AGA+LBW (0.5%), T+SGA+nonLBW (14.2%), T+SGA+LBW (7.1%), PT+LGA+nonLBW (1.6%), PT+LGA+LBW (0.2%), PT+AGA+nonLBW (3.7%), PT+AGA+LBW (3.6%) and PT+SGA+LBW (1.0%). The median prevalence of small types (six types, 37.6%) varied across studies and within regions and was higher in Southern Asia (52.4%) than in Sub-Saharan Africa (34.9%).

CONCLUSIONS

Further investigation is needed to describe the mortality risks associated with newborn types and understand the implications of this framework for local targeting of interventions to prevent adverse pregnancy outcomes in LMICs.

The Continued Impacts of the COVID-19 Pandemic on Education and Mental Health Among Sub-Saharan African Adolescents

PURPOSE

This multicountry survey assessed the levels and the determinants of the impacts of the pandemic on education and mental health among adolescents in sub-Saharan Africa and the potential factors that may exacerbate these adverse impacts.

METHODS

A phone survey was conducted among adolescents in nine diverse areas in Burkina Faso, Ethiopia, Ghana, Nigeria, and Tanzania between July and December 2021. Approximately 300 adolescents per area and 2,803 adolescents in total were included. The survey collected information on adolescents' sociodemographic characteristics, current COVID-19 preventive measures, and the impacts of the pandemic on daily activities, education, and mental health. Log-binomial models were used to calculate the adjusted prevalence ratios (aPRs) for determinants of education and mental health outcomes.

RESULTS

Overall, 17% of the adolescents were not receiving any education. Compared to boys, girls were 15% more likely than boys to lack fully in-person education (aPR: 1.15; 95% confidence interval [CI]: 1.02, 1.30). Rural residence was associated with 2.7 times the prevalence of not currently receiving any education (aPR: 2.68; 95% CI: 2.23, 3.22). Self-reported experience of the current impacts of the pandemic on daily activities was associated with a higher prevalence of possible psychological distress (aPR: 1.86; 95% CI: 1.55, 2.24), high anxiety level (aPR: 3.37; 95% CI: 2.25, 5.06), and high depression level (aPR: 3.01; 95% CI: 2.05, 4.41).

DISCUSSION

The COVID-19 pandemic presents continued challenges to adolescents' education and mental health. Multisectoral efforts are needed to ensure that adolescents in sub-Saharan Africa do not fall further behind due to the pandemic.

COVID-19 Preventive Practices, Psychological Distress, and Reported Barriers to Healthcare Access during the Pandemic among Adult Community Members in Sub-Saharan Africa: A Phone Survey

The COVID-19 pandemic has had serious negative health and economic impacts in sub-Saharan Africa. Continuous monitoring of these impacts is crucial to formulate interventions to minimize the consequences of COVID-19. This study surveyed 2,829 adults in urban and rural sites among five sub-Saharan African countries: Burkina Faso, Ethiopia, Nigeria, Tanzania, and Ghana. Participants completed a mobile phone survey that assessed self-reported sociodemographics, COVID-19 preventive practices, psychological distress, and barriers to healthcare access. A modified Poisson regression model was used to estimate adjusted prevalence ratios (aPRs) and 95% CIs to investigate potential factors related to psychological distress and barriers to reduced healthcare access. At least 15.6% of adults reported experiencing any psychological distress in the previous 2 weeks, and 10.5% reported that at least one essential healthcare service was difficult to access 2 years into the pandemic. The majority of participants reported using several COVID-19 preventive methods, with varying proportions across the sites. Participants in the urban site of Ouagadougou, Burkina Faso (aPR: 2.29; 95% CI: 1.74-3.03) and in the rural site of Kintampo, Ghana (aPR: 1.68; 95% CI: 1.21-2.34) had a higher likelihood of experiencing any psychological distress compared with those in the rural area of Nouna, Burkina Faso. Loss of employment due to COVID-19 (aPR: 1.77; 95% CI: 1.47-2.11) was also associated with an increased prevalence of psychological distress. The number of children under 5 years in the household (aPR: 1.23; 95% CI: 1.14-1.33) and participant self-reported psychological distress (aPR: 1.83; 95% CI: 1.48-2.27) were associated with an increased prevalence of reporting barriers to accessing health services, whereas wage employment (aPR: 0.67; 95% CI: 0.49-0.90) was associated with decreased prevalence of reporting barriers to accessing health services. Overall, we found a high prevalence of psychological distress and interruptions in access to healthcare services 2 years into the pandemic across five sub-Saharan African countries. Increased effort and attention should be given to addressing the negative impacts of COVID-19 on psychological distress. An equitable and collaborative approach to new and existing preventive measures for COVID-19 is crucial to limit the consequences of COVID-19 on the health of adults in sub-Saharan Africa.

Change in depression during the COVID-19 pandemic among healthcare providers in Addis Ababa, Ethiopia

Background

The COVID-19 pandemic has increased mental health problems among healthcare workers globally. However, studies from low- and middle-income countries on this matter were minimal. This study assessed the change in depression prevalence during the first year of the COVID-19 pandemic and associated factors among healthcare providers in Addis Ababa, Ethiopia.

Methods

We conducted surveys among healthcare workers in Addis Ababa at two-time points, September 2020 and October 2021. A total of 577 study participants were randomly selected based on registers obtained from professional associations. Computer-assisted telephone interviewing technique was used for data collection. The Patient Health Questionnaire (PHQ-9) was used to screen for depression. Multivariable logistic regression analysis was performed to identify potential factors associated with depression.

Result

The prevalence of depression among healthcare workers was 2.3% (95% CI [1.1-4.8]) in Time 1 and 6.5% (95% CI [4.1-10.1]) in Time 2; nearly a three-fold increase in Time 2 compared to Time 1. The most frequently reported symptoms at both times based on the PHQ-9 item were having poor energy, sleep problem, and anhedonia, while reported suicidal ideation was less than 5%. Depression showed a positive and significant association with a positive COVID-19 test result (AOR 7.25 95% CI [1.32-39.4]) in Time 1, and with being a female healthcare provider (AOR 3.96 95% CI [1.08-14.51]) and lack of COVID-19 related policy or guidelines at the workplace (AOR 3.22 95% CI [1.11-9.35]) in Time 2.

Conclusion

The prevalence of depression among healthcare workers tripled during the first year of the COVID-19 pandemic. Panic reaction to positive COVID-19 test result seems to have a negative effect at the beginning while lack of disease-specific prevention guidelines and comprehensive psychological interventions for healthcare providers had an adverse effect on the mental health of health workers.

Continued disruptions in health care services and mental health among health care providers during the COVID-19 pandemic in five sub-Saharan African countries

Background

Continuous monitoring of the pandemic’s impact on health service provision and mental health, COVID-19 perceptions, and compliance with prevention measures among health care providers (HCPs) can help with mitigating the pandemic’s negative effects.

Methods

A computer-assisted telephone interviewing (CATI) survey was conducted among 1499 HCPs in Burkina Faso (Ouagadougou), Ethiopia (Addis Ababa), Nigeria (Lagos and Ibadan), Tanzania (Dar es Salaam), and Ghana (Kintampo). Self-reported mental health, perceptions of the COVID-19 pandemic, and prevention measures available in the workplace were assessed. HCPs’ responses to questions regarding the impact of COVID-19 on nine essential health services were summed into a score; high service disruption was defined as a score higher than the total average score across all sites. Modified Poisson regression was used to identify potential factors related to high service disruption.

Results

Overall, 26.9% of HCPs reported high service disruption, with considerable differences across sites (from 1.6% in Dar es Salaam to 45.0% in Addis Ababa). A considerable proportion of HCPs reported experiencing mild psychological distress (9.4%), anxiety (8.0%), and social avoidance or rejection (13.9%) due to their profession. Participants in Addis Ababa (absolute risk ratio (ARR) = 2.10; 95% confidence interval (CI) = 1.59-2.74), Lagos (ARR = 1.65; 95% CI = 1.24-2.17), and Kintampo (ARR = 2.61; 95% CI = 1.94-3.52) had a higher likelihood of reporting high service disruption compared to those in Ouagadougou. Reporting ever-testing for COVID-19 (ARR = 0.82; 95% CI = 0.69-0.97) and the presence of COVID-19 guidelines in the workplace (ARR = 0.63; 95% CI = 0.53-0.77) were both associated with lower reported health service disruption among HCPs.

Conclusion

The COVID-19 pandemic continues to disrupt essential health services and present a challenge to HCPs’ mental health, with important differences across countries and settings; interventions are needed to mitigate these negative effects of the pandemic.

COVID-19 vaccine hesitancy and its determinants among sub-Saharan African adolescents

COVID-19 vaccine hesitancy among adolescents poses a challenge to the global effort to control the pandemic. This multi-country survey aimed to assess the prevalence and determinants of COVID-19 vaccine hesitancy among adolescents in sub-Saharan Africa between July and December 2021. The survey was conducted using computer-assisted telephone interviewing among adolescents in five sub-Saharan African countries, Burkina Faso, Ethiopia, Ghana, Nigeria, and Tanzania. A rural area and an urban area were included in each country (except Ghana, which only had a rural area), with approximately 300 adolescents in each area and 2662 in total. Sociodemographic characteristics and perceptions and attitudes on COVID-19 vaccines were measured. Vaccine hesitancy was defined as definitely not getting vaccinated or being undecided on whether to get vaccinated if a COVID-19 vaccine were available. Log-binomial models were used to calculate the adjusted prevalence ratios (aPRs) and 95% confidence intervals (CIs) for associations between potential determinants and COVID-19 vaccine hesitancy. The percentage of COVID-19 vaccine hesitancy was 14% in rural Kersa, 23% in rural Ibadan, 31% in rural Nouna, 32% in urban Ouagadougou, 37% in urban Addis Ababa, 48% in rural Kintampo, 65% in urban Lagos, 76% in urban Dar es Salaam, and 88% in rural Dodoma. Perceived low necessity, concerns about vaccine safety, and concerns about vaccine effectiveness were the leading reasons for hesitancy. Healthcare workers, parents or family members, and schoolteachers had the greatest impacts on vaccine willingness. Perceived lack of safety (aPR: 3.52; 95% CI: 3.00, 4.13) and lack of effectiveness (aPR: 3.46; 95% CI: 2.97, 4.03) were associated with greater vaccine hesitancy. The prevalence of COVID-19 vaccine hesitancy among adolescents is alarmingly high across the five sub-Saharan African countries, especially in Tanzania. COVID-19 vaccination campaigns among sub-Saharan African adolescents should address their concerns and misconceptions about vaccine safety and effectiveness.

Associations Between Global Diet Quality Score (GDQS) and Nutritional Status Among Rural Pregnant Women in Amhara Region, Ethiopia

Objectives

Nutritionally adequate diet during pregnancy is essential to promote the nutrition and health of pregnant women and their fetuses, but there are few measures to assess diet quality. We examined the associations of a new metric, the Global Diet Quality score (GDQS), with nutritional status among pregnant women in rural Amhara, Ethiopia.

Methods

We used baseline dietary data among 2363 pregnant women at ≤ 24 weeks’ gestation enrolled in the Enhancing Nutrition and Antenatal Infection Treatment for Maternal and Child Health (ENAT) study from July 2020 to December 2021. The GDQS was generated using the weekly consumption of 25 food groups. We assigned 0–1 serving/wk (0 point), 2–3 servings/wk (1 point), and ≥ 4 servings/wk (2 points) for 16 healthy foods, and the scoring was reversed for 7 unhealthy foods. One point was given only for 2–3 servings/wk of red meat and whole milk. Points for each group were summed (0–44 points) and categorized into quintiles. Multivariate linear regression or generalized linear models were used to evaluate the association of GDQS with nutritional status: BMI (continuous), underweight (BMI < 18.5 kg/m² vs. ≥18.5), overweight (BMI > 25.0 vs. ≤25.0), MUAC (continuous; MUAC <23 cm vs. ≥23.0 cm), hemoglobin concentration (continuous; anemia <11 g/dl), systolic and diastolic blood pressure (BP, mmHg), and hypertension (≥130 systolic BP or ≥ 85 diastolic BP). Models were adjusted for socioeconomic and demographic characteristics and health center location.

Results

In the ENAT cohort, at enrollment (mean 16.6 weeks’ gestation) 17% of pregnant women were underweight, 4.6% were overweight, 28.7% had MUAC < 23.0 cm, 5.8% were anemic, and 2.2% had hypertension. The mean (SD) GDQS was 18.2 (2.5). GDQS was negatively associated with underweight (RR = 0.96 of BMI < 18.5 per 1 point GDQS increment; 95%CI: 0.93, 0.99). GDQS was positively associated with MUAC (continuous: β = 0.05, P = 0.046) and negatively associated with the odds of MUAC (<23 cm) (RR = 0.97 of MUAC < 23 per 1 point GDQS increment; 95%CI: 0.94, 0.99). GDQS or GDQS quintile were not associated with hemoglobin concentration, anemia, BP, and hypertension.

Conclusions

GDQS was positively associated with maternal BMI and MUAC among pregnant women in rural Ethiopia, however, did not indicate any association with overweight or diet-related morbidity.

Funding Sources

Bill & Melinda Gates Foundation.

Community Access to Adequately Iodized Salt in Rural Amhara, Ethiopia

Objectives

To assess community access to adequately iodized salt in rural Amhara, Ethiopia.

Methods

We collected market and household salt samples from December 2020-January 2021 in West Gojam and South Gondar, Amhara, Ethiopia. A total of 24 salt samples were collected from markets randomly chosen in proximity to six rural health centers prior to the Enhancing Nutrition and Antenatal infection Treatment (ENAT study). 12 salt samples were unpackaged salt sold in open markets and 12 samples were packed samples procured from local shops. Household salt samples were also collected among mothers consecutively enrolled in the ENAT study over a one-month period at baseline. Quantitative assessment of iodine content was performed by iodometric titration at a central referral laboratory. In addition, a rapid qualitative salt assessment (MBI rapid test, Chennai, India) was done for 238 randomly selected households in walking proximity to the study health centers. The MBI test used rapid qualitative colorimetric methods, to test for adequacy of iodization (no color change: 0 ppm, light purple: &lt;15 ppm, dark purple &gt;15 ppm).

Results

 The median iodine titration level for local market salt was 37.1 ppm (range: 14.3–116.4). Fifteen (62.5%) samples were at recommended levels (15–40 ppm), 8(33.3%) were &gt;40 ppm and one sample &lt;15 ppm. The median iodine titration test for household samples was 42.7 ppm (range: 10.1–89.8); with 19 (33.3%) samples at the recommended levels, 33(57.9%) &gt;40 ppm, and 5(8.8%) of samples &lt;15 ppm. On the other hand, among the community based, household-level samples (n = 238) tested by MBI rapid kits, 8(3.4%) had no iodization, 116 (48.7%) were inadequately iodized (&lt;15 ppm), and 114(47.9%) were &gt;15 ppm.

Conclusions

 There is heterogeneity in the level of iodization in salts available in the markets in Amhara, with the majority of samples were iodized &gt;15 ppm; though almost 40% were above WHO recommended levels. At the household level, iodine content in nearly half of community-based samples were inadequate. Standardization of quality of market salt and optimal storage of iodized salt to prevent degradation at the household level are needed.

Funding Sources

Bill & Melinda Gates Foundation.

Health priority-setting for official development assistance in low-income and middle-income countries: a Best Fit Framework Synthesis study with primary data from Ethiopia, Nigeria and Tanzania

BACKGROUND

Decision making process for Official Development Assistance (ODA) for healthcare sector in low-income and middle-income countries involves multiple agencies, each with their unique power, priorities and funding mechanisms. This process at country level has not been well studied.

METHODS

This paper developed and applied a new framework to analyze decision-making process for priority setting in Ethiopia, Nigeria, and Tanzania, and collected primary data to validate and refine the model. The framework was developed following a scoping review of published literature. Interviews were then conducted using a pre-determined interview guide developed by the research team. Transcripts were reviewed and coded based on the framework to identify what principles, players, processes, and products were considered during priority setting. Those elements were further used to identify where the potential capacity of local decision-makers could be harnessed.

RESULTS

A framework was developed based on 40 articles selected from 6860 distinct search records. Twenty-one interviews were conducted in three case countries from 12 institutions. Transcripts or meeting notes were analyzed to identify common practices and specific challenges faced by each country. We found that multiple stakeholders working around one national plan was the preferred approach used for priority setting in the countries studied.

CONCLUSIONS

Priority setting process can be further strengthened through better use of analytical tools, such as the one described in our study, to enhance local ownership of priority setting for ODA and improve aid effectiveness.

COVID-19 Knowledge, Perception, Preventive Measures, Stigma, and Mental Health Among Healthcare Workers in Three Sub-Saharan African Countries: A Phone Survey

The coronavirus disease 2019 (COVID-19) pandemic is an unprecedented public health crisis globally. Understanding healthcare providers' (HCPs') knowledge and perceptions of COVID-19 is crucial to identifying effective strategies to improve their ability to respond to the pandemic in sub-Saharan Africa. A phone-based survey of 900 HCPs in Burkina Faso, Ethiopia, and Nigeria (300 per country) was conducted to assess knowledge, perceptions, COVID-19 prevention measures, stigma, and mental health of HCPs. Modified Poisson regression models were used to evaluate predictors of knowledge, perceptions, and prevention measures; adjusted risk ratios (ARRs) and 95% confidence intervals (CIs) were calculated. Three-fourths of the HCPs had adequate knowledge, and over half had correct perceptions of risk and high levels of self-reported prevention measures. The majority of the HCPs (73.7%) reported self-perceived social stigma. There was relatively low prevalence of depression (6.6%), anxiety (6.6%), or psychological distress (18%). Compared with doctors, being a nurse was associated with lower levels of knowledge (ARR: 0.83; 95% CI: 0.77-0.90) and was also negatively associated with having correct perceptions toward COVID-19 (AOR: 0.82; 95% CI: 0.73-0.92). HCPs treating COVID-19 patients had higher likelihood of having high levels of prevention measures (AOR: 1.37; 95% CI: 1.23-1.53). Despite high levels of knowledge among HCPs in sub-Saharan Africa, there is a need to improve COVID-19 perceptions and compliance with prevention measures as well as address social stigma toward HCPs to better ensure their safety and prepare them to deliver health services.

The COVID-19 Pandemic and Adolescents' Experience in Sub-Saharan Africa: A Cross-Country Study Using a Telephone Survey

The public health measures instituted by governments to combat the coronavirus disease 2019 (COVID-19) may cause developmental and educational losses to adolescents. The impacts of the COVID-19 pandemic and its mitigation strategies on adolescents in sub-Saharan Africa are unclear. This study aimed to examine adolescents' knowledge, perceptions, and practices related to COVID-19 and the impacts of the pandemic on the daily lives of adolescents in sub-Saharan Africa. The survey was conducted in Burkina Faso, Ethiopia, and Nigeria using computer-assisted telephone interviews to enable rapid and remote data collection. Two sites were included in each country, with approximately 300 adolescents per site and 1,795 adolescents in total. Variations across the six sites were noted for the proportions of the adolescents who could correctly identify all key COVID-19 symptoms (4-25%), transmission methods (16-59%), and prevention approaches (33-79%). Most (> 72%) of the adolescents were no longer going to school due to school closures. Many adolescents (23-81%) were not receiving any education during the pandemic. A considerable proportion of the adolescents (44-83%) self-assessed as having less ability to learn during the pandemic; many expected it to be very difficult to catch up on education after the pandemic. Decreases in the consumption of major food groups were common across sites. Urgent actions are needed in sub-Saharan Africa to address the inadequate knowledge of COVID-19 among adolescents and the impacts of the pandemic on adolescent education and nutrition.

Knowledge and Practice Related to COVID-19 and Mental Health among Adults in Sub-Saharan Africa

Coronavirus disease 2019 (COVID-19) is a public health emergency affecting the lives of millions of people globally. Different measures and extraordinary steps are being taken to contain the transmission of the virus. The levels of knowledge and implementation of preventive practices related to COVID-19 in sub-Saharan African countries are unclear. Additionally, there is a lack of evidence regarding the impacts of the pandemic on mental health. This study aimed to describe knowledge and practices related to COVID-19 and to assess mental health status among adults in three sub-Saharan African countries: Burkina Faso, Ethiopia, and Nigeria. A total of 1,797 adults were included in the survey, and data were collected using computer-assisted telephone interviews. The proportions of adults who identified more than 80% of COVID-19 symptoms, transmission methods, and prevention mechanisms were 69.9%, 79.2%, and 90.7%, respectively. The practice of preventive measures was relatively lower for avoiding social gatherings and disinfecting contaminated surfaces. Better education, urban residence, and believing the pandemic is real were factors associated with good knowledge on COVID-19 symptoms, transmission methods, and preventive actions. Additionally, being male was associated with good knowledge on symptoms and transmission methods, whereas being in an older age group was associated with knowledge of transmission methods. Mild, moderate, and severe psychological distress was reported by 20.6%, 5.9%, and 1.1% of the participants, respectively. Although this study found high levels of knowledge regarding COVID-19, interventions are needed to increase the uptake of recommended preventive practices among adults in sub-Saharan Africa.

Design and Field Methods of the ARISE Network COVID-19 Rapid Monitoring Survey

The coronavirus disease 2019 (COVID-19) pandemic has significant health and economic ramifications across sub-Saharan Africa (SSA). Data regarding its far-reaching impacts are severely lacking, thereby hindering the development of evidence-based strategies to mitigate its direct and indirect health consequences. To address this need, the Africa Research, Implementation Science, and Education (ARISE) Network established a mobile survey platform in SSA to generate longitudinal data regarding knowledge, attitudes, and practices (KAP) related to COVID-19 prevention and management and to evaluate the impact of COVID-19 on health and socioeconomic domains. We conducted a baseline survey of 900 healthcare workers, 1,795 adolescents 10 to 19 years of age, and 1,797 adults 20 years or older at six urban and rural sites in Burkina Faso, Ethiopia, and Nigeria. Households were selected using sampling frames of existing Health and Demographic Surveillance Systems or national surveys when possible. Healthcare providers in urban areas were sampled using lists from professional associations. Data were collected through computer-assisted telephone interviews from July to November 2020. Consenting participants responded to surveys assessing KAP and the impact of the pandemic on nutrition, food security, healthcare access and utilization, lifestyle, and mental health. We found that mobile telephone surveys can be a rapid and reliable strategy for data collection during emergencies, but challenges exist with response rates. Maintaining accurate databases of telephone numbers and conducting brief baseline in-person visits can improve response rates. The challenges and lessons learned from this effort can inform future survey efforts during COVID-19 and other emergencies, as well as remote data collection in SSA in general.

Reported Barriers to Healthcare Access and Service Disruptions Caused by COVID-19 in Burkina Faso, Ethiopia, and Nigeria: A Telephone Survey

The coronavirus disease 2019 (COVID-19) pandemic may have short-term and long-term impacts on health services across sub-Saharan African countries. A telephone survey in Burkina Faso, Ethiopia, and Nigeria was conducted to assess the effects of the pandemic on healthcare services from the perspectives of healthcare providers (HCPs) and community members. A total of 900 HCPs (300 from each country) and 1,797 adult community members (approximately 600 from each country) participated in the study. Adjusted risk ratios (ARRs) and 95% confidence intervals (CIs) were computed using modified Poisson regression. According to the HCPs, more than half (56%) of essential health services were affected. Child health services and HIV/surgical/other services had a slightly higher percentage of interruption (33%) compared with maternal health services (31%). A total of 21.8%, 19.3%, and 7.7% of the community members reported that their family members and themselves had difficulty accessing childcare services, maternal health, and other health services, respectively. Nurses had a lower risk of reporting high service interruptions than physicians (ARR, 0.85; 95% CI, 0.56–0.95). HCPs at private facilities (ARR, 0.71; 95% CI, 0.59–0.84) had a lower risk of reporting high service interruptions than those at governmental facilities. Health services in Nigeria were more likely to be interrupted than those in Burkina Faso (ARR, 1.38; 95% CI, 1.19–1.59). Health authorities should work with multiple stakeholders to ensure routine health services and identify novel and adaptive approaches to recover referral services, medical care, maternal and child health, family planning, immunization and health promotion, and prevention during the COVID-19 era.

Impact of COVID-19 on Nutrition, Food Security, and Dietary Diversity and Quality in Burkina Faso, Ethiopia and Nigeria

Coronavirus disease 2019 (COVID-19) can have far-reaching consequences for developing countries through the combined effects of infection and mortality, and the mitigation measures that can impact food systems and diets. Using a mobile platform, this cross-sectional study evaluated the effect of COVID-19 on food prices and dietary quality for 1797 households in Nouna and Ouagadougou in Burkina Faso, Addis Ababa and Kersa in Ethiopia, and Lagos and Ibadan in Nigeria. We assessed the consumption of 20 food groups during the previous 7 days. The dietary diversity scores (DDS) and Prime Diet Quality Scores (PDQS) were used to assess dietary diversity and quality. We used generalized estimating equation (GEE) linear models to evaluate associations between price changes for staples, pulses, vegetables, fruits, and animal source foods (ASFs) with the DDS and PDQS PDQS. Most participants reported increasing prices of staples, pulses, fruits, vegetables and ASF, and ≥ 40% reported the decreased consumption of staples, legumes, and other vegetables and fruits. The DDS (except in Kersa and Ouagadougou) and PDQS were lower during the COVID-19 pandemic. Higher pulse prices were associated with lower DDS (estimate, -0.35; 95% confidence interval [CI], -0.74 to 0.03; P = 0.07) in the combined analysis and in Burkina Faso (estimate, -0.47; 95% CI, -0.82 to -0.11). Higher vegetable prices were positively associated with the DDS (estimate, 0.22; 95% CI, 0.08 to 0.37). Lower crop production (estimate, -0.54; 95% CI, -0.80 to -0.27) was associated with lower DDS. The price increases and worsening dietary diversity and quality call for social protection and other strategies to increase the availability and affordability of nutrient-rich foods during the COVID-19 pandemic and public health emergencies.

Feasibility, Acceptability, and Adherence of Nutritional Supplement Amongst Pregnant Women in Rural Ethiopia

Objectives

Providing balanced protein energy (BEP) supplementation to pregnant women in low-and-middle income countries has been shown to improve pregnancy outcomes. The objective of this study was to assess the feasibility, acceptability, and adherence of a proposed BEP product among pregnant women in rural Ethiopia prior to initiation of a clinical effectiveness study.

Methods

This formative study was conducted from October-November 2018 among pregnant women in the rural Amhara region of Ethiopia, prior to the “Enhancing Nutrition and Antenatal Infection Treatment (ENAT)” study [ISRCTN15116516]. Questionnaires to assess acceptability of a micronutrient fortified corn soy blend (CSB) BEP supplement were administered using a 7-point Likert scale (0 = strongly disagree, to 7 = strongly agree) after 2 and 4 weeks of utilization. Acceptability domains included: color, taste, texture, odor, portion size, ease of use, and adult favorability. Women were also given weekly provisions of daily sachets of the supplement and monitored weekly for adherence over one month.

Results

39 women participated in the study and 33 completed the study at 4 weeks. Quantitative results demonstrated high acceptability (mean Likert score &gt;6 of 7) for the following domains: color, odor and perceived adult favorability at mid and end point. Scores on acceptability and perception of the product remained generally stable through the duration of use. The average number of sachets consumed was 6.4 in week 1, 6.6 in week 2, 7 in week 3, and 6.9 in week 4. 43% of women consumed the portion in one sitting, whereas 57% of women split up the portion to consume throughout the day. The majority (66%) of women reported consuming the full daily serving. 26% of respondents reported sharing the supplement with family members.

Conclusions

These findings show that most women in rural Amhara, Ethiopia, found the BEP supplement acceptable and had positive perceptions of the product. Sharing of the product and completion of the full daily serving were important considerations. Overall, the BEP supplement demonstrated good feasibility of implementation in our study population. Future studies should consider utilizing such strategies to understand factors that may affect uptake and adherence of nutritional supplements.

Funding Sources

Bill & Melinda Gates Foundation.

Dietary Practices Among Pregnant Women in Rural Amhara, Ethiopia

Objectives

Malnutrition affects 25% of women in Ethiopia. We are conducting a study to determine the impact of a prenatal nutrition intervention on maternal and infant health in Ethiopia. The objective of this formative study was to better describe dietary practices among pregnant women and community members in rural Ethiopia prior to initiation the parent study.

Methods

This formative study was conducted from October-November 2018 among pregnant women and community members in the rural Amhara region of Ethiopia, prior to the “Enhancing Nutrition and Antenatal Infection Treatment (ENAT)” study [ISRCTN15116516]. 28 in-depth interviews (IDIs) were conducted among 16 pregnant women and 12 community members. IDIs were recorded, transcribed, and translated. We used a grounded theory approach and inductive reasoning for content analysis of interview transcripts.

Results

Fasting norms in the Ethiopian Orthodox religion had a significant impact on dietary behaviors which occurs for more than 200 days annually. Community members indicated that fasting during pregnancy is common and is also supported and encouraged by religious leaders and community members. Accordingly, women adhered to fasting restrictions during pregnancy, and many women maintained a vegan diet under direction of local religious leaders. Furthermore, many women reported restricting dietary intake in pregnancy to prevent growth of the fetus because of the concern for obstructed labor. A women's diet depended on her husbands’/family earnings and household food preferences. Sharing of meals is a cultural norm; the husband is served first, with the remaining portions to the pregnant women/children. Pregnant women in the area also reported regular consumption of a locally brewed alcohol (“tella”), as it is believed to have lower alcohol levels. These findings demonstrate the impact of traditional and cultural beliefs on dietary decisions amongst pregnant women in this population.

Conclusions

Reduced food intake in pregnancy is common in this population, due to fasting, reduced appetite, and food restriction to avoid pregnancy complications. Context-specific interventions are needed, and this formative work will inform the future delivery and education regarding nutrition interventions in rural Ethiopia.

Funding Sources

Bill & Melinda Gates Foundation (OPP1184363).

Impact of COVID-19 on Nutrition, Food Security and Dietary Diversity and Quality in Burkina Faso, Ethiopia and Nigeria

Objectives

COVID-19 has far-reaching consequences for developing countries through the combined effects of infection and mortality and unintended consequences from mitigation measures. COVID-19 can adversely impact food systems and dietary diversity for populations. This cross-sectional study evaluated, using a mobile platform, the effect of COVID-19 on food prices and dietary diversity and quality, among 1797 households in Nouna and Ouagadougou (Burkina Faso), Addis Ababa and Kersa (Ethiopia), and Lagos and Ibadan (Nigeria).

Methods

Dietary intake was assessed as the frequency of consumption of 20 food groups over the previous 7 days. Dietary diversity scores (DDS; range: 0–10) and Prime Diet Quality Score (PDQS; range: 0–40) assessed dietary diversity and quality. Linear regression models were used to evaluate associations between changes in the prices of staples, pulses, vegetables, fruits, and animal source foods (ASF) with DDS and PDQS during COVID-19.

Results

Most households reported increases in prices of staples, pulses, fruits, vegetables and ASF, and ≥40% reported decreased consumption of staples, legumes, ASF, other vitamin A rich vegetables, other vegetables and other fruits, and lower DDS and PDQS compared to the period before the COVID-19 emergency. Increases in pulse prices were associated with lower DDS (estimate − 0.35, 95% CI: −0.61, −0.09). Lower crop production (estimate − 0.70, 95% CI: −1.02, −0.37), and skipping meals (estimate − 0.39, 95% CI: −0.56, −0.21) or not eating for a whole day (estimate − 0.23, 95% CI: −0.43, −0.03) were also associated with lower DDS.

Conclusions

The price increases and worsening dietary diversity and quality call for social protection and other strategies to increase the availability and affordability of nutrient-rich foods during the COVID-19 pandemic and other public health emergencies.

Funding Sources

The Bill and Melinda Gates Foundation Grant as well as institutional support from the Heidelberg Institute of Global Health, Germany and the Harvard T.H. Chan School of Public Health, USA, supported this work.

Incidence of Mite-Vectored Viruses of Wheat in the Texas High Plains and Interactions With Their Host and Vector

Mite-vectored virus diseases of wheat are common throughout the Great Plains and cause significant economic losses to growers each year. These diseases are caused by Wheat streak mosaic virus (WSMV), Triticum mosaic virus (TriMV), and Wheat mosaic virus (WMoV), all of which are transmitted by the wheat curl mite (WCM), Aceria tosichella Keifer. New wheat cultivars with tolerance or resistance to WSMV have been released recently, but their widespread cultivation and potential impact on mite-transmitted virus incidence in the Texas Panhandle was unknown. A total of 648 symptomatic wheat samples were collected from 26 counties, predominately in the Texas Panhandle, and tested by enzyme-linked immunosorbent assay (ELISA) for WSMV, TriMV, and WMoV. Samples that tested negative by ELISA were subsequently tested by real-time quantitative PCR (qPCR) for each virus. Approximately 93% of the samples tested by ELISA were positive for WSMV, 43% were positive for TriMV, and 7% were positive for WMoV. Eleven samples tested positive only for TriMV, but none were positive only for WMoV. When samples that tested negative for the different viruses by ELISA were retested by real-time qPCR, detection of each virus was significantly increased. When results of the ELISA test and qPCR were combined, 100% of the 648 samples tested positive for WSMV, approximately 94% were positive for TriMV, and 23% were positive for WMoV. This demonstrated that the incidence of TriMV in the Texas High Plains is much greater than previously reported. The fact that real-time qPCR revealed over a 2-fold increase in the incidence of TriMV and a 3-fold increase in WMoV demonstrated that the ELISA test, which is commonly used by diagnostic laboratories in the Great Plains, should not be used for studies requiring a high degree of sensitivity and accuracy in virus detection. After initial virus infection status was determined, samples that tested positive for WSMV and TriMV were further observed for WCM infestation. A total of 292 samples were inspected and a total of 101 mites were collected from 40 tillers. Individual mites and the tillers from which they were recovered were tested by real-time qPCR to determine how copy numbers of WSMV and TriMV in mites and host tissue compared, and whether the WSMV/TriMV copy number ratio in individual mites was similar to that of the host tissue from which they were collected. In all mites and tillers tested, the WSMV copy number was always higher than that of TriMV and copy numbers of both viruses were always higher in plant tissue than in mites. Although there was a significant correlation between the WSMV/TriMV copy number ratio in plant tissue and in associated mites, the correlation coefficient was very low (r = 0.31, P = 0.0248). In the majority of comparisons, the WSMV/TriMV ratio was higher in individual mites than in the tiller from which they were recovered. The reason for this increase is unknown but indicates that mites may preferentially acquire WSMV from tillers coinfected with WSMV and TriMV, a finding that could have significant implications for virus transmission and disease epidemiology.

Relationships Between Early Wheat Streak Mosaic Severity Levels and Grain Yield: Implications for Management Decisions

Wheat streak mosaic (WSM) caused by Wheat streak mosaic virus, which is transmitted by the wheat curl mite (Aceria tosichella), is a major yield-limiting disease in the Texas High Plains. In addition to its impact on grain production, the disease reduces water-use efficiency by affecting root development. Because of the declining Ogallala Aquifer water level, water conservation has become one of the major pressing issues in the region. Thus, questions are often raised as to whether it is worthwhile to irrigate infected fields in light of the water conservation issues, associated energy costs, and current wheat prices. To address some of these questions, field experiments were conducted in 2013 and 2016 at two separate locations to determine whether grain yield could be predicted from disease severity levels, assessed early in the spring, for potential use as a decision tool for crop management, including irrigation. In both fields, disease severity assessments started in April, using a handheld hyperspectral radiometer with which reflectance measurements were taken weekly in multiple plots in arbitrarily selected locations across the fields. The relationship between WSM severity levels and grain yield for the different assessment dates were determined by fitting reflectance and yield values into the logistic regression function. The model predicted yield levels with r² values ranging from 0.67 to 0.85 (P < 0.0001), indicating that the impact of WSM on grain yield could be fairly well predicted from early assessments of WSM severity levels. As the disease is normally progressive over time, this type of information will be useful for making management decisions of whether to continue irrigating infected fields, especially if combined with an economic threshold for WSM severity levels.

Population Dynamics of Released Potato Psyllids and their Bacteriliferous Status in Relation to Zebra Chip Incidence in Caged Field Plots

Potato psyllids vector 'Candidatus Liberibacter solanacearum' (Lso), the putative causal agent of potato zebra chip (ZC). Currently, sticky traps are the primary psyllid monitoring tools used by growers for making management decisions. However, the reliability of sticky traps in predicting psyllid numbers in potato fields has always been questioned. In 2013 and 2014, experiments were conducted in covered field plots at the Texas A&M AgriLife Research Station at Bushland to investigate the relationships among initial psyllid numbers, psyllids captured on sticky traps and their Lso status, and zebra chip incidence. Three densities of Lso-positive psyllids (5, 15, or 30/cage) were released under 2-week-old potato canopies with four replications in plot sizes of 7.6 to 9 m by 5 rows. Psyllids were released under the first plant in the center row and monitored weekly with a yellow sticky trap from the opposite end. Number of plants with zebra chip symptoms also was counted weekly beginning one month after infestation with psyllids. The total number of psyllids captured on sticky traps and disease incidence levels generally corresponded to the levels of psyllid density treatments (5 < 15 < 30), but the differences became more apparent toward the end of the experiments. Psyllid numbers in the different density treatments fluctuated more or less in synchrony over time, which appeared to reflect periodic emergence of new generations of psyllids. Initially, all captured psyllids tested positive for Lso. However, the proportions of psyllids testing positive declined dramatically after a few weeks, which suggested that the new generations of psyllids were devoid of Lso. Over all, less than 50% of captured psyllids tested positive for the pathogen. The decline in proportions of psyllids testing positive for Lso following successive generations has significant relevance to field situations and may partly explain why there are generally low percentages of Lso-positive psyllids under field conditions.

Significance and Epidemiological Aspects of Late-Season Infections in the Management of Potato Zebra Chip

Zebra chip (ZC) of potato is putatively caused by the fastidious, phloem-limited bacterium 'Candidatus Liberibacter solanacearum' (Lso), which is transmitted by the potato psyllid (Bactericera cockerelli). The disease, which significantly impacts both crop yield and quality, was first identified in the United States from south Texas in 2000. It reached epidemic levels in north Texas and certain production areas in Colorado, Nebraska, and New Mexico from 2004 to 2007 and it caused severe losses in fields in Oregon, Washington, and Idaho in 2011. The potato plant is susceptible to infection at all developmental stages, but disease management programs have focused on vector control through early and repeated insecticide applications, in an effort to minimize early to midseason infections which are most damaging. Growers often terminate spray programs 2 to 3 weeks prior to crop harvest due to lack of visible treatment effects on crop yield or quality. However, recent studies on vector transmission and host-pathogen interactions have revealed that late-season infections pose a significant, previously unrecognized, threat to crop quality. The pathogen can move from an infected leaf to tubers within 2 days; however, tubers infected less than 1 week before harvest will remain asymptomatic and the pathogen will be undetectable. When these tubers are placed into storage they are assumed to be disease free. However, Lso can continue to multiply in respiring tubers during storage, resulting in reduced tuber quality. Likewise, if plants become infected a few days before vines are killed, ZC can continue to develop in infected tubers before they are harvested. Perspectives on the significance of late-season infections and some of the more important issues associated with those infections are discussed.

Effects of Potato-Psyllid-Vectored 'Candidatus Liberibacter solanacearum' Infection on Potato Leaf and Stem Physiology

The bacterium 'Candidatus Liberibacter solanacearum' is associated with zebra chip disease (ZC), a threat to potato production in North America and New Zealand. It is vectored by potato psyllids. Previous studies observed that 'Ca. L. solanacearum' infection causes potato tubers to undergo ZC-symptom-associated shifts in physiology, such as increased levels of amino acids, sugars, and phenolics. However, little is known about how 'Ca. L. solanacearum' infections caused by psyllid vector feeding may affect metabolism in potato foliage and stems. This study compared metabolism in potato plants fed upon by 'Ca. L. solanacearum'-positive psyllids with potato plants not exposed to psyllids. Foliar levels of asparagine, aspartic acid, glutamine, fructose, glucose, sucrose, a ferulic acid derivative, and quinic acid were lower in 'Ca. L. solanacearum'-inoculated than noninfected plants. However, foliar levels of proline, serine, four phenolic compounds, and most terpenoids were greater in 'Ca. L. solanacearum'-inoculated than noninfected plants. Upper stem levels of asparagine and aspartic acid, upper and lower stem levels of ellagitannins and most monoterpenoids, and lower stem level of sesquiterpenoids were greater in 'Ca. L. solanacearum'-inoculated than noninfected plants. These results suggest that many defense-related terpenoid compounds might increase in plants which had psyllids inoculate 'Ca. L. solanacearum'. This could impact progression and spread of ZC.

Similarities and differences in physiological responses to 'Candidatus Liberibacter solanacearum' infection among different potato cultivars

Zebra chip disease (ZC), putatively caused by the fastidious bacterium 'Candidatus Liberibacter solanacearum', is a threat to potato growers worldwide. However, little is known about biochemical shifts in different potato genotypes in response to 'Ca. L. solanacearum' infection. To address this, 'Red La Soda', 'Russet Norkotah', and 'FL 1867' potato were infected with 'Ca. L. solanacearum' 4, 3, 2, and 1 weeks before harvest to observe variability in cultivar responses to 'Ca. L. solanacearum' infection. ZC symptoms, 'Ca. L. solanacearum' titers, and tuber biochemistry were assessed. Red La Soda tubers exhibited greater symptoms when infected for 4 weeks than Russet Norkotah or FL 1867 tubers. 'Ca. L. solanacearum' titers did not vary among cultivars. Tuber levels of amino acids, carbohydrates, and phenolics varied among cultivars but no consistent trends were observed. Individual amino acids and phenolics were greater in FL 1867 than Red La Soda, whereas others were greater in Red La Soda or Russet Norkotah than FL 1867. Most amino acids, carbohydrates, and phenolics were positively associated with infection duration and symptoms regardless of cultivar. Associations between most of the evaluated compounds and 'Ca. L. solanacearum' titer were positive in Red La Soda. However, no associations between 'Ca. L. solanacearum' quantity and compounds were observed in FL 1867 and Russet Norkotah.

Zebra Chip Disease Development in Relation to Plant Age and Time of 'Candidatus Liberibacter solanacearum' Infection

A 2-year field study was conducted to evaluate plant susceptibility to 'Candidatus Liberibacter solanacearum', the putative causal agent of zebra chip disease (ZC). Incubation period of ZC, the rate of symptom progress, and the rate of pathogen population growth were evaluated for individual plants infested on different weeks after emergence. In foliage, incubation period was between 21 and 28 days. The pathogen was detected within leaf tissue in 3 to 4 weeks, regardless of the time of infestation. The rates of foliar symptom progress and pathogen population growth were uniform among all infestations. Although symptoms were observed in only 1.3% of tubers from plants infested 2 weeks before harvest, 74% of these tubers tested positive for the pathogen. There was a positive correlation between symptom severity and titer in the foliage. Within tubers, however, the relationship was negative but nonsignificant. Pathogen titer reached detectable levels some time between 7 to 14 days following infestation. Although yield reduction was significant only in plants infested during early stages of their growth, chemical management of potato psyllids needs to be continued until at least a week before harvest to minimize ZC impact on the tuber quality.

Characterization of management and environmental factors associated with regional variations in potato zebra chip occurrence

Potato zebra chip (ZC), caused by the bacterial pathogen 'Candidatus Liberibacter solanacearum', which is vectored by the potato psyllid (Bactericera cockerelli), has caused widespread damage to U.S. potato production ever since its first discovery in south Texas in 2000. To determine the influence of environmental factors and management practices on ZC occurrence, data on management and meteorological variables, field locations, and psyllid counts were collected over a 3-year period (2010 to 2012) from six locations across the central United States (south Texas to Nebraska). At these locations, ZC-symptomatic plants were counted in 26 fields from systematically established 20 m × 30 m plots around the field edges and field interiors. Mean numbers of symptomatic plants per plot were classified into two intensity classes (ZC ≤ 3 or ZC > 3) and subjected to discriminant function and logistic regression analyses to determine which factors best distinguish between the two ZC intensity classes. Of all the variables, location, planting date, and maximum temperature were found to be the most important in distinguishing between ZC intensity classes. These variables correctly classified 88.5% of the fields into either of the two ZC-intensity classes. Logistic regression analysis of the individual variables showed that location accounted for 90% of the variations, followed by planting date (86%) and maximum temperature (70%). There was a low but significant (r = -0.44983, P = 0.0211) negative correlation between counts of psyllids testing positive for pathogen and latitudinal locations, indicating a south-to-north declining trend in counts of psyllids testing positive for the pathogen. A similar declining trend also was observed in ZC occurrence (r = -0.499, P = 0.0094).

Zebra chip disease and potato biochemistry: tuber physiological changes in response to 'Candidatus Liberibacter solanacearum' infection over time

Zebra chip disease, putatively caused by the bacterium 'Candidatus Liberibacter solanacearum', is of increasing concern to potato production in Mexico, the United States, and New Zealand. However, little is known about the etiology of this disease and changes that occur within host tubers that result in its symptoms. Previous studies found that increased levels of phenolics, amino acids, defense proteins, and carbohydrates in 'Ca. L. solanacearum'-infected tubers are associated with symptoms of zebra chip. This study was conducted to quantify variations in levels of these biochemical components in relation to the time of infestation, symptom severity, and 'Ca. L. solanacearum' titer. Levels of phenolics, peroxidases, polyphenol oxidases, and reducing sugars (glucose and, to some extent, fructose) changed during infection, with higher levels occurring in tubers infected at least 5 weeks before harvest than in those infected only a week before harvest and those of controls. Compared with the apical tuber ends, greater levels of phenolics, peroxidases, and sucrose occurred at the basal (stolon attachment) end of infected tubers. With the exception of phenolics, concentrations of the evaluated compounds were not associated with 'Ca. L. solanacearum' titer. However, there were significant associations between biochemical responses and symptom severity. The lack of a linear correlation between most plant biochemical responses and 'Ca. L. solanacearum' titer suggests that shifts in metabolic profiles are independent of variations in 'Ca. L. solanacearum' levels.

Transmission efficiency of 'Candidatus Liberibacter solanacearum' and potato zebra chip disease progress in relation to pathogen titer, vector numbers, and feeding sites

ABSTRACT With diseases caused by vector-borne plant pathogens, acquisition and inoculation are two primary stages of the transmission, which can determine vector efficiency in spreading the pathogen. The present study was initiated to quantify acquisition and inoculation successes of 'Candidatus Liberibacter solanacearum', the etiological agent of zebra chip disease of potato, by its psyllid vector, Bactericera cockerelli (Hemiptera: Triozidae). Acquisition success was evaluated in relation to feeding site on the host plant as well as the acquisition access period. Inoculation success was evaluated in relation to vector number (1 and 4) on the plants. Acquisition success was influenced by the feeding site on the plant. The highest acquisition success occurred when insects had access to the whole plant. The results of the inoculation study indicated that the rate of successfully inoculated plants increased with the vector number. Plants inoculated with multiple psyllids had higher bacterial titer at the point of inoculation. Although disease incubation period was significantly shorter in plants inoculated with multiple psyllids, this effect was heterogeneous across experimental blocks, and was independent of pathogen quantity detected in the leaflets 3 days postinoculation. Disease progress was not affected by bacterial quantity injected or psyllid numbers.

Assessments of the Edge Effect in Intensity of Potato Zebra Chip Disease

Zebra chip is a newly emerging potato disease which imparts dark colorations on fried chips, rendering them unmarketable. The disease is associated with the phloem-limited proteobacterium 'Candidatus Liberibacter solancearum', vectored by the potato psyllid Bactericera cockerelli. First reported from Mexico in the mid-1990s, the disease was observed for the first time in Texas in 2000 and is now prevalent in several potato-producing regions of the United States. In this study, we were interested in investigating whether there are edge effects in zebra chip intensity that can be assessed as a "foot print" of the associated insect vector. In 2009, we conducted studies in three fields in the Texas Panhandle in paired plots of 10 by 20 m around the field edges and 100 m infield in which symptomatic plants were counted just before harvest. The number of plot pairs (edge and infield) ranged from 15 to 18 depending on the size of the fields. In a separate study, temporal disease progress was assessed in two fields around the edges of the center-pivot circle in approximately 10-by-450-m areas. In 2010, the paired plot studies were repeated in 10 potato fields in Texas, Kansas, and Nebraska. Zebra chip intensity data from the paired-plot studies for both years were analyzed using the Wilcoxon's signed-rank test, a nonparametric equivalent of the classical (parametric) paired t test. In the 2009 study in all three fields, the edge plots had significantly greater zebra chip intensity than the infield plots (P < 0.05). Edge plots in the 2010 study also had greater zebra chip intensity in all fields and the differences were significant in the majority of fields (P < 0.05). In the diseases progress study in both fields, weekly zebra chip intensity on the edges reached its maximum after the third week of its first detection, and the disease progress curves were best fitted with the second-degree polynomial (quadratic) for both fields. The 2-year study clearly demonstrated that zebra chip intensity in potato fields was greater on the edges than in the infields. This finding has significant implications for psyllid management because greater emphasis in psyllid control strategy can be directed toward the edges for better results.

Spatial Patterns and Spread of Potato Zebra Chip Disease in the Texas Panhandle

Zebra chip (ZC) is a disease that is affecting potato production in the southwestern United States and in other countries, and which has been linked to potato psyllids (Bactericera cockerelli) that harbor the bacterial plant pathogen 'Candidatus Liberibacter solanacearum'. Until recently, the epidemiology of ZC was unknown, motivating research to elucidate the spatial and temporal patterns of ZC infections in potato fields. Studies were performed in multiple commercial potato fields located in the Texas Panhandle, wherein locations of ZC-affected potato plants were georeferenced or counted within large plots and along belt transects consisting of contiguous 10-by-10-m quadrats. By employing distance- and area-based spatial statistical methods, it was determined that locations of ZC infections in potato fields departed from a completely spatially random pattern, instead appearing as clusters comprising infected plants situated in close proximity to one another, with clusters interspersed with numerous solitary infections. Disease progress curves of ZC clusters were generally well described by exponential growth and quadratic polynomial models. Numbers of ZC infections within disease clusters gradually increased over multiple weeks, with foliar disease symptoms first appearing during the tuber bulking stage. ZC infections were not found to be continuously present across fields, because many quadrats along belt transects contained zero or only a few infections while others had numerous infections. Consequently, the frequency of ZC infections within belt transect quadrats was well described by negative binomial and zero-inflated negative binomial distributions, in agreement with observed clustering of infections and distance-based spatial statistical results.

Satellite Remote Sensing of Wheat Infected by Wheat streak mosaic virus

The prevalence of wheat streak mosaic, caused by Wheat streak mosaic virus, was assessed using Landsat 5 Thematic Mapper (TM) images in two counties of the Texas Panhandle during the 2005-2006 and 2007-2008 crop years. In both crop years, wheat streak mosaic was widely distributed in the counties studied. Healthy and diseased wheat were separated on the images using the maximum likelihood classifier. The overall classification accuracies were between 89.47 and 99.07% for disease detection when compared to "ground truth" field observations. Omission errors (i.e., pixels incorrectly excluded from a particular class and assigned to other classes) varied between 0 and 12.50%. Commission errors (i.e., pixels incorrectly assigned to a particular class that actually belong to other classes) ranged from 0 to 23.81%. There were substantial differences between planted wheat acreage reported by the United States Department of Agriculture-National Agricultural Statistics Service (USDA-NASS) and that detected by image analyses. However, harvested wheat acreage reported by USDA-NASS and that detected by image classifications were closely matched. These results indicate that the TM image can be used to accurately detect and quantify incidence of wheat streak mosaic over large areas. This method appears to be one of the best currently available for identification and mapping disease incidence over large and remote areas by offering a repeatable, inexpensive, and synoptic strategy during the course of a growing season.

Movement of Bactericera cockerelli (Heteroptera: Psyllidae) in relation to potato canopy structure, and effects on potato tuber weights

With the threat of new plant diseases on the increase, plant disease epidemiology requires research on pathogen vector movement. Here, releases were performed in planted potato fields of different ages and canopy structures, located in the Texas Panhandle, to evaluate the range of movement of the potato psyllid Bactericera cockerelli (Sulc.). This insect is a known causative agent of psyllid yellows disease, and is a vector of the reported etiological agents of zebra chip disease of potato, 'Candidatus Liberibacter solanacearum/psyllaurous'. Based on collections of B. cockerelli immatures along transects 9 m long radiating in four cardinal directions from release points, adult females dispersed considerable distances, regardless of plant age or canopy structure. Immature abundance declined along transects and were well described by linear and nonlinear models, but abundance patterns did not differ among the different planting dates and canopy structures. However, unequal immature abundance was detected among the four cardinal directions, with more immatures generally collected along transects to the north and west of release points, opposite of prevailing winds in the area at the time of release. Plots where B. cockerelli were released had significantly lower mean potato tuber weights than control plots with no B. cockerelli. However, few plots with B. cockerelli released in them had declining trends in tuber weights with increasing distance from release points.

Effects of Wheat streak mosaic virus on Root Development and Water-Use Efficiency of Hard Red Winter Wheat

Greenhouse and field studies were conducted to determine the effects of Wheat streak mosaic virus (WSMV), a member of the family Potyviridae, on root development and water-use efficiency (WUE) of two hard red winter wheat (Triticum aestivum) cultivars, one susceptible and one resistant to WSMV. In the greenhouse studies, wheat cultivars were grown under three water regimes of 30, 60, and 80% soil saturation capacity. After inoculation with WSMV, plants were grown for approximately 4 weeks and then harvested. Root and shoot weights were measured to determine the effect of the disease on biomass. In all water treatments, root biomass and WUE of inoculated susceptible plants were significantly less (P < 0.05) than those of the noninoculated control plants. However, in the resistant cultivar, significance was only found in the 30 and 60% treatments for root weight and WUE, respectively. Field studies were also conducted under three water regimes based on reference evapotranspiration rates. Significant reductions in forage, grain yield, and crop WUE were observed in the inoculated susceptible plots compared with the noninoculated plots. Both studies demonstrated that wheat streak mosaic reduces WUE, which is a major concern in the Texas Panhandle because of limited availability of water.

Characterization and Epidemiological Significance of Potato Plants Grown from Seed Tubers Affected by Zebra Chip Disease

An emerging disease of potato in the United States, known as "Zebra Chip" or "Zebra Complex" (ZC), is increasing in scope and threatens to spread further. Here, we report on studies performed to understand the role of tuberborne ZC in the epidemiology of this disease. Depending on variety, up to 44% of ZC-affected seed tubers (ZCST) were viable, producing hair sprouts and weak plants. Chip discoloration in progeny tubers of ZCST was more severe than those from ZC-asymptomatic seed tubers but varied depending on whether progeny tubers or foliage were positive or negative for 'Candidatus Liberibacter solanacearum'. A low percentage of greenhouse-grown plants produced by ZCST tested positive for 'Ca. Liberibacter'. No adult potato psyllids became infective after feeding upon these plants but they did acquire 'Ca. Liberibacter' from field-grown plants produced by ZCST. Plants with new ZC infections near plants produced by ZCST were not significantly different from healthy plants, whereas plants affected with ZC from infectious potato psyllids had significantly more ZC infections near either plants produced by ZCST or healthy plants. We conclude that, in areas where ZC is currently established, plants produced by ZCST do not significantly contribute to ZC incidence and spread within potato fields.

Quantifying wheat yield across the field as a function of wheat streak mosaic intensity: a state space approach

Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite Aceria tosichella, is one of the major limiting factors in wheat production in the Texas Panhandle. The mites are blown by wind into wheat fields from nearby volunteer wheat fields or fields supporting vegetation which harbor virulent mites. Consequently, gradients of wheat streak severity are often observed stretching from the edges of wheat fields into the center or beyond. To describe the magnitude of the spatial relationships between grain yield and wheat streak intensity across the field, studies were conducted in 2006 and 2007 in three infected fields. Wheat streak severity was quantified with reflectance measurements (remote sensing) at 555-nm wave length using a hand-held radiometer. Measurements were taken in several equally spaced 1 m(2) locations along a total of eight transects and grain yield was assessed from a 0.8 m(2) area of each location. State space analysis was used to describe the relationships in which yield data and reflectance values were used as dependent and explanatory variables, respectively. A structural time series model was formulated as a state space model where the unobserved components were modeled explicitly. In the analysis the state of yield at current location (d) was related to the state of wheat streak intensity either at current locations (d) or lagged locations with autoregressive values of the first order (d-1) or greater. There were significant cross-correlations between yield and wheat streak intensity up to distances of 150 m (P < or = 0.05). Grain yield at the current position was significantly correlated with reflectance values at the same location and/or at lagged locations. The spatial aspects of the yield-reflectance relationships were best described by state space models with stochastic trends without slopes or deterministic trends with or without slopes. The models correctly predicted almost all of the observed yield values as a function of wheat streak intensity across the field within the 95% confidence interval. Results obtained in this study suggest that state space methodology can be a powerful tool in the study of plant disease spread as a function of other variables.

Distribution and Recovery of Tilletia indica Teliospores from Regulated Wheat Fields in Texas

Eight wheat fields from the Karnal bunt-regulated regions within Texas were grid sampled to gain a better understanding of the ecology and epidemiology of teliospores produced by the causal agent, Tilletia indica. Teliospores from 25-g aliquots of soil from each grid point were extracted using a size-selective sieving sucrose-centrifugation procedure. Teliospores were recovered from all eight fields and, in some cases, from every grid point within a field. Total teliospore numbers ranged from 0 to 1,305 per 25 g of soil. Over 70% of the total grid sampled points contained one or more teliospores. The relation between soil chemical and physical characteristics and teliospore numbers from each field was evaluated. In general, no consistent, significant trend could be made between soil factors and teliospore numbers. Geostatistics were used to analyze data from grid points and create contour maps. Teliospore distribution was aggregated in four of the fields, random in three of the fields, and discontinuous (neither random nor aggregated) in a single field. This is the first report of widespread distribution and high teliospore numbers from wheat field soils in the United States.

The Influence of Tillage on Dispersal of Tilletia indica Teliospores from a Concentrated Point Source

A study was conducted to determine the impact of tillage on dispersal of Tilletia indica teliospores from a concentrated point source in Arizona. The infested source was created using a 300-ml teliospore suspension, containing approximately 9.0 × 10⁴ teliospores/ml, sprayed onto a 1-by-3-m soil area. Approximately 400 g of soil was collected before tillage treatments, representing the teliospore baseline, and after each of five disk passes, to an approximate depth of 20 cm, through the infestation source (n = 597). Soil samples were collected along three parallel lines extending from the infested area at increments of 1, 3, or 10 m to a total distance of 10, 30, and 50 m, respectively. Teliospores were recovered from soil samples by a combined size-selective sieving sucrose-centrifugation technique. Immediately following teliospore infestation, an average of 3.6 × 10³ teliospores per 25 g of soil sample were recovered from the infestation area. Two different trends in recoverable teliospores occurred at 0- to 10-m sampling distances following five plow passes: either a decrease in the number of teliospores recovered, represented at points 0, 1, and 2 m, or an increase in recoverable teliospores found at points 3 to 10 m. The study was repeated twice for a total of three experiments, and teliospores were recovered to a maximum distance of 24 m. However, the numbers recovered from distances beyond 10 m were sporadic. Based on data from this research, we conclude that teliospores are not distributed in large quantities to great distances by tillage and, therefore, tillage cannot account for the spatial distribution of teliospores in many infested wheat fields.

Rainfall and temperature distinguish between Karnal bunt positive and negative years in wheat fields in Texas

Karnal bunt of wheat, caused by the fungus Tilletia indica, is an internationally regulated disease. Since its first detection in central Texas in 1997, regions in which the disease was detected have been under strict federal quarantine regulations resulting in significant economic losses. A study was conducted to determine the effect of weather factors on incidence of the disease since its first detection in Texas. Weather variables (temperature and rainfall amount and frequency) were collected and used as predictors in discriminant analysis for classifying bunt-positive and -negative fields using incidence data for 1997 and 2000 to 2003 in San Saba County. Rainfall amount and frequency were obtained from radar (Doppler radar) measurements. The three weather variables correctly classified 100% of the cases into bunt-positive or -negative fields during the specific period overlapping the stage of wheat susceptibility (boot to soft dough) in the region. A linear discriminant-function model then was developed for use in classification of new weather variables into the bunt occurrence groups (+ or -). The model was evaluated using weather data for 2004 to 2006 for San Saba area (central Texas), and data for 2001 and 2002 for Olney area (north-central Texas). The model correctly predicted bunt occurrence in all cases except for the year 2004. The model was also evaluated for site-specific prediction of the disease using radar rainfall data and in most cases provided similar results as the regional level evaluation. The humid thermal index (HTI) model (widely used for assessing risk of Karnal bunt) agreed with our model in all cases in the regional level evaluation, including the year 2004 for the San Saba area, except for the Olney area where it incorrectly predicted weather conditions in 2001 as unfavorable. The current model has a potential to be used in a spray advisory program in regulated wheat fields.

Assessment of Regional Site-Specific Sorghum Ergot Severity Potential Using Radar-Rainfall Measurement

Sorghum ergot, caused by Claviceps africana, generally requires cool weather and humid conditions for optimum infection. Rainfall reportedly is not required for infection as long as relative humidity is high. However, occurrence of high humidity in the Texas Panhandle during the summer is usually associated with rain showers, and ergot incidence in the region has been observed to be associated with rain events. These events are often irregular and can vary within a small area both in incidence and intensity. Existing ground weather stations are too far apart to provide accurate representation of localized rainfall events. Radar-based precipitation measurements have a resolution of 4 × 4 km out to 230 km from the radar location. In the present study, radar rainfall measurements were used to assess regional site-specific sorghum ergot potential in the Texas Panhandle. The results have a potential for development of a web-based ergot risk assessment system in which growers can enter the GPS locations of their fields and determine whether management actions are necessary.

Weather Factors Associated with Development of Sorghum Ergot in the Texas Panhandle

Since its first introduction in 1997, sorghum ergot, caused by Claviceps africana, has been observed yearly in the Texas Panhandle, where it has caused occasional epidemics in hybrid-seed production fields. To determine the effect of weather factors on ergot severity, inoculation experiments were conducted in 2003 and 2004 using sequentially planted sorghum plants. Sorghum flowers were inoculated with three inoculum concentrations (1 × 10⁴, 1 × 10⁵, or 1 × 10⁶ spores/ml) prepared from infected sorghum panicles producing fresh honeydew. Each year, inoculations were conducted several times during sorghum flowering periods so that time of inoculations would coincide with different weather conditions. Weather variables (temperature, relative humidity, wind speed, precipitation, and radiation) were collected using an onsite weather station. Infected and uninfected florets were counted 8 to 13 days after inoculation, and the percentage of infected florets per sorghum panicle (severity) was determined. In both years, temperature and relative humidity were the predominant factors responsible for variations in sorghum ergot severity with all inoculum densities. Relationship between ergot severity and each of the two variables depended on inoculum density. Measurable infection occurred at a maximum temperature of 34°C with 1 × 10⁶ spores/ml, while there was little or no infection at 30°C with 1 × 10⁴ spore/ml. Cumulative departures from minimum relative humidity and maximum temperature infection thresholds 12, 18, 24, 36, 48, and 72 h after inoculation were calculated and regressed against ergot severity for each inoculum level. Cumulative departures of hourly temperature and relative humidity from maximum temperature and minimum relative humidity infection thresholds 18 and 24 h after inoculation were best related to sorghum ergot severity (R ² = 89 and 91; P < 0001, respectively). Models based on these two time-durations then were used in predicting a regional site-specific ergot severity potential using radar-estimated rainfall.

Characterization and Distribution of Two Races of Phialophora gregata in the North-Central United States

ABSTRACT Genetic variation and variation in aggressiveness in Phialophora gregata f. sp. sojae, the cause of brown stem rot of soybean, was characterized in a sample of 209 isolates from the north-central region. The isolates were collected from soybean plants without regard to symptoms from randomly selected soybean fields. Seven genotypes (A1, A2, A4, A5, A6, M1, and M2) were distinguished based on DNA fingerprinting with microsatellite probes (CAT)(5) and (CAC)(5), with only minor genetic variation within the A or M genotypes. Only the A1, A2, and M1 genotypes were represented by more than one isolate. The A genotypes dominated in the eastern Iowa, Illinois, and Ohio samples, whereas the M genotypes were dominant in samples from western Iowa, Minnesota, and Missouri. In growth chamber experiments, isolates segregated into two pathogenicity groups based on their aggressiveness toward soybean cvs. Kenwood and BSR101, which are relatively susceptible and resistant, respectively, to brown stem rot. In both root dip inoculation and inoculation by injecting spores into the stem near the ground line (stab inoculations), isolates of the A genotypes caused greater foliar symptoms and more vascular discoloration than isolates of the M genotypes on both cultivars of soybean. All isolates caused foliar symptoms in both cultivars and in three additional cultivars of soybean with resistance to brown stem rot. Greater differences between the A and M genotypes were seen in foliar symptoms than in the linear extent of xylem discoloration, and greater differences were seen in Kenwood than in BSR101. Inoculation of these genotypes into five cultivars of soybean with different resistance genes to brown stem rot showed a genotype x cultivar interaction. A similar distinction was found in an earlier study of the adzuki bean pathogen, P. gregata f. sp. adzukicola, and consistent with the nomenclature of that pathogen, the soybean pathogens are named the aggressive race (race A) and the mild race (race M) of P. gregata f. sp. sojae.