Genetic Basis of Maize Resistance to Multiple Insect Pests: Integrated Genome-Wide Comparative Mapping and Candidate Gene Prioritization.

Several species of herbivores feed on maize in field and storage setups, making the development of multiple insect resistance a critical breeding target. In this study, an association mapping panel of 341 tropical maize lines was evaluated in three field environments for resistance to fall armyworm (FAW), whilst bulked grains were subjected to a maize weevil (MW) bioassay and genotyped with Diversity Array Technology's single nucleotide polymorphisms (SNPs) markers. A multi-locus genome-wide association study (GWAS) revealed 62 quantitative trait nucleotides (QTNs) associated with FAW and MW resistance traits on all 10 maize chromosomes, of which, 47 and 31 were discovered at stringent Bonferroni genome-wide significance levels of 0.05 and 0.01, respectively, and located within or close to multiple insect resistance genomic regions (MIRGRs) concerning FAW, SB, and MW. Sixteen QTNs influenced multiple traits, of which, six were associated with resistance to both FAW and MW, suggesting a pleiotropic genetic control. Functional prioritization of candidate genes (CGs) located within 10-30 kb of the QTNs revealed 64 putative GWAS-based CGs (GbCGs) showing evidence of involvement in plant defense mechanisms. Only one GbCG was associated with each of the five of the six combined resistance QTNs, thus reinforcing the pleiotropy hypothesis. In addition, through in silico co-functional network inferences, an additional 107 network-based CGs (NbCGs), biologically connected to the 64 GbCGs, and differentially expressed under biotic or abiotic stress, were revealed within MIRGRs. The provided multiple insect resistance physical map should contribute to the development of combined insect resistance in maize.

Cassava whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) in East African farming landscapes: a review of the factors determining abundance.

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a pest species complex that causes widespread damage to cassava, a staple food crop for millions of households in East Africa. Species in the complex cause direct feeding damage to cassava and are the vectors of multiple plant viruses. Whilst significant work has gone into developing virus-resistant cassava cultivars, there has been little research effort aimed at understanding the ecology of these insect vectors. Here we assess critically the knowledge base relating to factors that may lead to high population densities of sub-Saharan African (SSA) B. tabaci species in cassava production landscapes of East Africa. We focus first on empirical studies that have examined biotic or abiotic factors that may lead to high populations. We then identify knowledge gaps that need to be filled to deliver sustainable management solutions. We found that whilst many hypotheses have been put forward to explain the increases in abundance witnessed since the early 1990s, there are little published data and these tend to have been collected in a piecemeal manner. The most critical knowledge gaps identified were: (i) understanding how cassava cultivars and alternative host plants impact population dynamics and natural enemies; (ii) the impact of natural enemies in terms of reducing the frequency of outbreaks and (iii) the use and management of insecticides to delay the development of resistance. In addition, there are several fundamental methodologies that need to be developed and deployed in East Africa to address some of the more challenging knowledge gaps.

The use of common bean (Phaseolus vulgaris) traditional varieties and their mixtures with commercial varieties to manage bean fly (Ophiomyia spp.) infestations in Uganda.

The bean fly (Ophiomyia spp.) is considered the most economically damaging field insect pest of common beans in Uganda. Despite the use of existing pest management approaches, reported damage has remained high. Forty-eight traditional and improved common bean varieties currently grown in farmers' fields were evaluated for resistance against bean fly. Data on bean fly incidence, severity and root damage from bean stem maggot were collected. Generalized linear mixed model (GLMM) revealed significant resistance to bean fly in the Ugandan traditional varieties. A popular resistant traditional variety and a popular susceptible commercial variety were selected from the 48 varieties and evaluated in pure and mixed stands. The incidence of bean fly infestation on both varieties in mixtures with different arrangements (systematic random versus rows), and different proportions within each of the two arrangements, was measured and analysed using GLMMs. The proportion of resistant varieties in a mixture and the arrangement type significantly decreased bean fly damage compared to pure stands, with the highest decrease in damage registered in the systematic random mixture with at least 50 % of resistant variety. The highest reduction in root damage, obvious 21 days after planting, was found in systematic random mixtures with at least 50 % of the resistant variety. Small holder farmers in East Africa and elsewhere in the world have local preferences for growing bean varieties in genetic mixtures. These mixtures can be enhanced by the use of resistant varieties in the mixtures to reduce bean fly damage on susceptible popular varieties.

Undiagnosed diabetes mellitus and impaired glucose tolerance among hypertensive patients in Mulago Hospital, Kampala, Uganda

Both diabetes and impaired glucose tolerance (IGT) are rising globally, and are known to be associated with hypertension. We have assessed the prevalence of, and risk factors for, abnormal glucose tolerance (AGT) among hypertensive patients in Kampala, Uganda. A total of 320 randomly chosen hypertensive patients were studied, demographic and other data collected, and an oral glucose tolerance test (OGTT) carried out. AGT was found in 237 (74%) patents ­ 50% had IGT and 24% type 2 diabetes. The following factors were significantly associated with AGT: body mass index (BMI) over 28.0 kg/m2 (p=0.003), family history of diabetes (p=0.002), physical inactivity (p=0.001), alcohol consumption (p=0.01), and a systolic blood pressure (BP) over 140 mmHg. We conclude that diabetes and IGT are highly prevalent in hypertensive patients and screening for these conditions in such patients should be considered

A study of risk factors associated with Newcastle disease epidemics in village free-range chickens in Uganda.

A prospective study of risk factors associated with outbreaks of Newcastle disease (ND) in indigenous free-range chickens was carried out in three agro-ecological zones in eastern Uganda. Sixty households keeping chickens were randomly selected and studied from March 2004 to February 2005, covering rainy and dry seasons. Data on ND outbreaks, risk factors and flock dynamics were collected using an interviewer-administered questionnaire, while ND outbreaks were confirmed by haemagglutination inhibition test. Multivariate survival analyses were performed to identify the risk factors for Newcastle disease outbreaks. Although the survival time against ND was longer (> 100 days) in the dry compared to the rainy season, incidence in the two seasons was not significantly different (p > 0.05). None of the factors investigated was significantly associated with ND. However, purchasing of restocking chickens from the market and neighbourhood (hazard ratio [HR] = 1.79; 95% confidence interval [CI] 0.89-3.60), the presence of migratory wild birds (HR = 1.70; 95% CI 0.65-4.48) and being in agro-ecological zone 1 (HR = 1.48; 95% CI 0.66-3.36) showed a positive but non-significant association with risk for ND. To understand the roles of other domestic poultry species in the epidemiology of ND in rural free-range chickens, virus isolation and molecular characterization of isolates in addition to more prospective cohort studies with a larger sample size and similarly long period of follow-up are needed.

Epidemiological assessment of rinderpest surveillance and control in Uganda between 1990 and 1998.

Based on passive and active data, we report on an epidemiological assessment of surveillance and control of rinderpest (RP) in Uganda between 1990 and 1998. Active data were collected by administration of questionnaires to animal health personnel and their auxiliaries and to stockowners in six selected districts of eastern and northeastern Uganda. Passive data were extracted from vaccination and seromonitoring reports, and from field and laboratory reports. RP events were classified as "confirmed outbreaks", "suspected outbreaks" and "rumours". The classification of 56% of the RP events as "suspected outbreaks" indicates the difficulty in investigating disease outbreaks in Uganda. Although vaccination coverage and seroprevalence were <85% (the recommended target), they nevertheless corresponded well-reflecting effective vaccination. However, because of the low seroprevalence, a sizable population of cattle in Uganda remained at risk of RP. The agreement between the local and national disease reporting systems was low-to-moderate (kappa=0.39); this indicates inefficiency in disease reporting. Risk factors for RP outbreaks were cattle raids and communal grazing. Based on overlaid thematic maps of seroprevalence, vaccination coverage and RP events, close spatial and temporal associations were observed between cattle raids, transhumance and outbreaks and rumours. The high-risk areas were in the eastern and northeastern parts of the country. The results of this study support a phase approach of following the OIE pathway.

Morbidity and mortality among diabetic patients admitted to Mulago Hospital, Uganda.

OBJECTIVES: To document the causes of admission, clinical presentation and outcome of patients admitted with diabetes mellitus to our medical wards. SETTING: Medical wards of Mulago Hospital, teaching hospital and national referral for the government of Uganda. STUDY DESIGN: Cross-sectional descriptive non-interventional study of diabetic medical admissions. RESULTS: During the study period 129 (4.2%) patients with diabetes mellitus out of 3103 total medical admissions were admitted. The commonest cause of admission was uncontrolled diabetes (48.3%) but infections were present in 27.7% of all the study patients. The commonest infections were pneumonia (15%) and urinary tract infections (11.8%). Diabetic ketoacidosis (DKA) was a cause of admission in 9.2% of all the study subjects. Glycaemic control was satisfactory among 50.6% (HbA1c less than 7) despite 84.5% of the study subjects being hyperglycaemic at admission (mean random blood sugar 20±9.0 mmol/L). Fifty-point seven of the subjects had long term complications of diabetes at admission with hypertension (53.8%) and peripheral neuropathy (38.3%) being the commonest. There were 13 deaths (10.8%) and 61.5% of the deaths were among patients admitted with infections. The average length of hospitalisation was 9.5±4 days. CONCLUSION: The results show that the commonest causes of admission were uncontrolled diabetes and infections. The mortality rate was 10.8%.

Disseminated aspergillus fumigatus infection: case report.

A case of disseminated aspergillus fumigatus infection is reported in a 43 year old Ugandan female with no known immune system disorder(not neutropenic and HIV-1 sero negative). She presented with multiple cutaneous ulcers, recurrent empyema thoracis, a past history of intra-abdominal abscess and bowel infarction. Empirical treatment for tuberculosis was previously given without improvement. A diagnosis of aspergillus fumigatus based on a combination of tissue wet potassium hydroxide preparation, fungal culture and tissue histologic typing was made. Despite antifungal therapy with intravenous amphotericin B infusion in 5% dextrose, after a normal baseline renal function test, the patient died in the second week of admission. Autopsy showed disseminated aspergillosis involving the pleural space, pericardium, spleen, and meningitis in addition to the cutaneous sites. Disseminated aspergillus fumigatus infection in a non-immunocompromised is rare antemortem diagnosis. This case highlights the difficulty in making a diagnosis in the face of many endemic conditions with similar presentation.

Renal glycosuria treated as diabetes mellitus: case report.

A case of renal glycosuria is reported. A 55 year old female was diagnosed and treated in an upcountry hospital for diabetes mellitus. She developed symptoms of hypoglycaemia while on an oral hypoglycaemic agent, leading to her admission in Mulago Hospital. Persistent glycosuria was noted despite treatment and normal serum glucose. Oral glucose tolerance test and timed urine glucose showed a normal curve but high urine sugar. A diagnosis of renal glycosuria was made, oral hypoglycaemic therapy was stopped, patient improved and was discharged. Though renal glycosuria is a benign condition, mistaken diagnosis for diabetes mellitus puts patients at risk of hypoglycaemia due to treatment. Diagnosis of the condition requires physicians' awareness of its existence in our community and the use of Marbles' criteria obviates confusion with diabetes mellitus though it does not absolutely exclude Fanconi syndrome.

The presentation of newly-diagnosed diabetic patients in Uganda.

We assessed the clinical characteristics of newly-diagnosed diabetic patients presenting to the Mulago Hospital Diabetic Clinic for the first time between 1 January 1993 and 10 August 1994. There were 252 patients: 117 men and 135 women. Mean age at onset of diabetes was 45 years (range 2-87 years) and peak incidence was at 40-49 years. Body mass index (BMI) was available in only 71 patients, of whom 53.5% (33.8% female, 19.7% male) were overweight (BMI > 25 in women, in > 27 men) and 11.3% (8.5% men, 2.8% women) were underweight (BMI < 20). Obesity was more marked in young women. Almost all patients presented with the classical symptoms of diabetes, and the majority were severely hyperglycaemic. A family history of diabetes was identified in 16%. Concurrent illnesses at diagnosis of diabetes were unusual. Sepsis was commonest (11.9%), followed by malaria (7.8%), tuberculosis (1.2%), AIDS (1.2%) and pancreatitis (0.8%). Peripheral neuropathy was present in 46.4% of patients, hypertension (BP > 150/100) in 27.3%, impotence in 22.2% of the men, proteinuria in 17.1%, ischaemic heart disease in 4.8%, foot ulcers in 4.0% and cataracts in 3.2%. Insulin was the most commonly prescribed treatment (52.8%); 31% of patients received oral hypoglycaemic agents, only 15.1% were managed on diet only, and 1.2% opted for herbal medicine.

A reappraisal of increased intracranial pressure (ICP)

A rise in the intracranial pressure can result from a variety of conditions both traumatic and non-traumatic. Whereas in many of the cases the mechanisms leading to a rise in ICP are obvious; in a few such as endocrine causes and benign intracranial hypertension (BIH); the mechanisms are not known