Stability and estimation problems related to a stage-structured epidemic model.

In this work, we consider a class of stage-structured Susceptible-Infectious (SI) epidemic models which includes, as special cases, a number of models already studied in the literature. This class allows for n different stages of infectious individuals, with all of them being able to infect susceptible individuals, and also allowing for different death rates for each stage-this helps to model disease induced mortality at all stages. Models in this class can be considered as a simplified modelling approach to chronic diseases with progressive severity, as is the case with AIDS for instance. In contradistinction to most studies in the literature, we consider not only the questions of local and global stability, but also the observability problem. For models in this class, we are able to construct two different state-estimators: the first one being the classical high-gain observer, and the second one being the extended Kalman filter. Numerical simulations indicate that both estimators converge exponentially fast, but the former can have large overshooting, which is not present in the latter. The Kalman observer turns out to be more robust to noise in measurable data.

[Electrocardiographic and echocardiographic abnormalities in patients with cirrhosis due to viral hepatitis B: about 60 cases reported in the Hepatogastroenterologic Department at the Aristide Le Dantec Hospital in Dakar (HALD)]. / Anomalies électrocardiographiques et échocardiographiques au cours de la cirrhose virale b: à propos de 60 cas au service d'hepato-gastroenterologie de l'Hopital Aristide Le Dantec de Dakar (HALD).

This study aimed to evaluate the electrocardiographic abnormalities in patients with cirrhosis due to viral hepatitis B and to identify their determinants. We conducted a prospective study in the Hepatogastroenterologic Department and in the Department of Cardiology at the Aristide Le Dantec Hospital in Dakar over a period of 8 months. All patients with cirrhosis due to viral hepatitis B and without a history of heart disease were included in the study. We collected and analyzed the epidemiological, clinical, echographic, endoscopic, electrocardiographic, echocardiographic (2D and Doppler) data and laboratory data from all patients. Sixty patients were enrolled. The prevalence of cirrhosis due to viral hepatitis B was 3.4%. The average age was 41 years and the sex-ratio was 1.6 (37 men). Cirrhosis was classified as Child-Pugh B in 29 patients (49%), Child-Pugh C and Child Pugh A in 20 patients (33%) and 11 patients (18%) respectively. The most common electrocardiographic abnormalities included left ventricular hypertrophy and QTc interval prolongation detected in 27 patients (45%) and 24 patients (40%) respectively. Statistical analysis showed an association between prolonged QTc interval and the severity of cirrhosis (p = 0.01, RR = 2, CI = 0.24 - 0.341). Echocardiographic abnormalities were dominated by left ventricle dilatation (58.3%) and cardiac hyperoutput (43.3%), with an average output of 6.05 l/ min. Statistical analysis revealed a significant association between cirrhosis severity and cardiac hyperoutput (p = 0.003; CI: 95%, 2,883-38,58; RR = 2). A total of 14 patients (23.3%) had latent cirrhotic cardiomyopathy. Cirrhosis due to viral hepatitis B can cause a wide range of different cardiac abnormalities. These include morphological and/or electrophysiological abnormalities whose severity appears to be correlated with cirrhosis severity.

Delivering Vitamin A Supplements to Children Aged 6-59 Months: Comparing Delivery through Campaigns and through Routine Health Services in Senegal.

BACKGROUND: Using twice-yearly campaigns such as Child Health Days to deliver vitamin A supplements has been a key strategy over the last 2 decades, and was an important component in helping reach the Millennium Development Goals in child health. As countries move to strengthen their routine health services under the Sustainable Development Goals, efforts are underway to shift supplementation from campaign to routine delivery. OBJECTIVE: The aim of this study was to compare cost, coverage, and user satisfaction between twice-yearly campaigns and routine delivery of vitamin A supplements in Senegal. METHODS: Information was collected on cost, coverage, and user satisfaction with both types of delivery, using administrative data, interviews at various levels in the health system, and focus group discussions with caregivers. Both qualitative and quantitative information were obtained, for 2 regions using routine delivery and 2 regions using campaign delivery. RESULTS: Routine delivery receives fewer dedicated resources. Coverage is lower, especially of children >12 mo of age. Districts undertake outreach ("mini-campaigns") to try to improve coverage in regions using routine delivery, in effect using a hybrid approach. Some mothers prefer the administration of supplements at a health facility as it is perceived as more hygienic and involving professional health workers, but others, especially those living further away, prefer house-to-house delivery which was the norm for the campaign mode. CONCLUSIONS: Advance planning for the shift to routine delivery is important in maintaining coverage, as is strengthening the primary health care system by having an appropriate ratio of salaried workers to population. When the system relies heavily on volunteers, and the small incentive payments to volunteers are discontinued, coverage suffers. Routine delivery also relies on good record-keeping and hence literacy. Community understanding of, and support for, supplementation are even more important for routine than for campaign delivery.

[An unusual cause of jaundice]. / Une cause inhabituelle d'ictère.

Hepatic impairment is common during hyperthyroidism. It is most often asymptomatic. Hyperthyroidism revealed by jaundice has been rarely described in the literature. We here report the case of a 52-year old patient in Dakar (Senegal) presenting with jaundice associated with pruritus. Laboratory tests showed elevated alanine aminotransferases (1.1 N), aspartate aminotransferase(1.5 N), alkaline phosphatases (3 N), gamma glutamyl transferases (1.3 N) and bilirubinemia (22 N). Abdominal ultrasound was normal. A toxic or drug-related cause, bile duct obstruction, viral or autoimmune hepatitis as well as primary biliary cholangitis were excluded. The dosage of thyroid hormones showed elevated free T4, 24 ng/dL (9-20 ng/dL) and undetectable plasma TSH less than 0.01µUI/mL (0,35-4,94 IU/mL). TSH receptor antibodies were positive 7.04 IU/L (n < 1.75 IU/L). Thyroid ultrasound objectified diffuse homogeneous hypervascular goiter. The diagnosis of hepatic impairment secondary to Graves-Basedow disease without cardiac dysfunction was retained. Clinical outcome and laboratory test results were favorable under carbimazole. Jaundice can be an indicator of hyperthyroidism. An investivation of clinical signs and laboratory parameters for hyperthyroidism is essential in patients with unexplained jaundice.

[Viral Hepatitis B: clinical, paraclinical and evolutionary features within the Hepatogastroenterology Department at the Aristide Le Dantec Hospital: about 728 cases]. / Hépatite virale B: aspects cliniques, paracliniques et évolutifs dans le service d'Hépato Gastroentérologie de l'Hôpital Aristide Le Dantec: à propos de 728 cas.

Viral Hepatitis B is a major public health problem in sub-Saharan Africa accounting for approximately 65 million of chronic carriers and 56.000 deaths per year. Our study aims to investigate the epidemiological paraclinical, therapeutic and evolutionary features of viral hepatitis B in patients followed up in our Department and to describe their serological profiles. We conducted a retrospective, longitudinal study in the Hepatogastroenterology Department at the Aristide Le Dantec Hospital in Dakar from 2010 to 2014. We included all HBsAg positive patients followed up on an ambulatory basis or hospitalized. We collected data from 728 medical records of patients infected with Hepatitis B virus: 7 cases of acute hepatitis, 442 cases of chronic infections, 161 cases of cirrhosis and 118 cases of hepatocellular carcinoma. The average age of patients was 33 years [14 - 83 years] with a sex ratio of 2.2. The circumstances in which it was diagnosed included systematic screening (26.2%), right hypochondrium pain (23%) and donation of blood (18.6%). Fifty nine were Hepatitis B virus mono-infected and had chronic active hepatitis. Inactive carriers were 118. Serological status was undetermined in 252 patients due to clinical examination inadequacy related to economic constraints. Antiviral Hepatitis B treatment wasn't performed in 58 patients. Patients' virologic and biochemical response after 120 weeks of treatment with Tenofovir was 85% and 100% respectively. Hepatitis B virus is a major cause of liver disease in Senegal.

Safety monitoring of artemisinin combination therapy through a national pharmacovigilance system in an endemic malaria setting.

BACKGROUND: The National Malaria Control Programme in Senegal, introduced since 2006, artemisinin-based combination therapy (ACT administration) for the treatment of uncomplicated malaria cases. In this framework, an anti-malarial pharmacovigilance plan was developed and implemented in all public health services. This study investigated the occurrence of Adverse Drug Events (ADEs) after ACT. METHODS: The study was conducted between January 2007 and December 2009. It was based on spontaneous reports of ADEs in public health facilities. Data on patient demographic characteristics, dispensing facility, adverse signs and symptoms and causality were collected from a total of 123 patients. RESULTS: The age range of these patients was six months to 93 years with a mean of 25.9 years. Of the reported symptoms, 46.7% were related to the abdomen and the digestive system. Symptoms related to the nervous system, skin and subcutaneous tissue, circulatory and respiratory systems and general symptoms and signs were 7%, 9.7%, 3.5% and 31.3%, respectively. Causality results linked 14.3% of symptoms to Falcimon® (Artesunate-Amodiaquine) with certainty. Effects were classified as mild and severe in 69.1% and 7.3% of cases respectively while 23.6% were serious. All patients with serious ADEs were hospitalized. One death was reported in a patient who had taken 24 pills at once. CONCLUSION: These results confirm the need to develop and implement pharmacovigilance systems in malaria endemic countries in order to monitor the safety of anti-malarial treatments.

Scale-up of home-based management of malaria based on rapid diagnostic tests and artemisinin-based combination therapy in a resource-poor country: results in Senegal.

BACKGROUND: Effective case management of malaria requires prompt diagnosis and treatment within 24 hours. Home-based management of malaria (HMM) improves access to treatment for populations with limited access to health facilities. In Senegal, an HMM pilot study in 2008 demonstrated the feasibility of integrated use of RDTs and ACT in remote villages by volunteer Home Care Providers (HCP). Scale-up of the strategy began in 2009, reaching 408 villages in 2009 and 861 villages in 2010. This paper reports the results of the scale-up in the targeted communities and the impact of the strategy on malaria in the formal health sector. METHODS: Data reported by the HCPs were used to assess their performance in 2009 and 2010, while routine malaria morbidity and mortality data were used to assess the impact of the HMM programme. Two high transmission regions where HMM was not implemented until 2010 were used as a comparison. RESULTS AND DISCUSSION: From July 2009 through May 2010, 12582 suspected cases were managed by HCPs, 93% (11672) of whom were tested with an RDT. Among those tested, 37% (4270) had a positive RDT, 97% (4126) of whom were reported treated and cured. Home care providers referred 6871 patients to health posts for management: 6486 with a negative RDT, 119 infants < 2 months, 105 pregnant women, and 161 severe cases. There were no deaths among these patients. In 2009 compared to 2008, incidence of suspected and confirmed malaria cases, all hospitalizations and malaria-related hospitalizations decreased in both intervention and comparison regions. Incidence of in-hospital deaths due to malaria decreased by 62.5% (95% CI 43.8-81.2) in the intervention regions, while the decrease in comparison regions was smaller and not statistically significant. CONCLUSION: Home-based management of malaria including diagnosis with RDT and treatment based on test results is a promising strategy to improve the access of remote populations to prompt and effective management of uncomplicated malaria and to decrease mortality due to malaria. When scaled-up to serve remote village communities in the regions of Senegal with the highest malaria prevalence, home care providers demonstrated excellent adherence to guidelines, potentially contributing to a decrease in hospital deaths attributed to malaria.

Major reduction in anti-malarial drug consumption in Senegal after nation-wide introduction of malaria rapid diagnostic tests.

BACKGROUND: While WHO recently recommended universal parasitological confirmation of suspected malaria prior to treatment, debate has continued as to whether wide-scale use of rapid diagnostic tests (RDTs) can achieve this goal. Adherence of health service personnel to RDT results has been poor in some settings, with little impact on anti-malarial drug consumption. The Senegal national malaria control programme introduced universal parasite-based diagnosis using malaria RDTs from late 2007 in all public health facilities. This paper assesses the impact of this programme on anti-malarial drug consumption and disease reporting. METHODS AND FINDINGS: Nationally-collated programme data from 2007 to 2009 including malaria diagnostic outcomes, prescription of artemisinin-based combination therapy (ACT) and consumption of RDTs in public health facilities, were reviewed and compared. Against a marked seasonal variation in all-cause out-patient visits, non-malarial fever and confirmed malaria, parasite-based diagnosis increased nationally from 3.9% of reported malaria-like febrile illness to 86.0% over a 3 year period. The prescription of ACT dropped throughout this period from 72.9% of malaria-like febrile illness to 31.5%, reaching close equivalence to confirmed malaria (29.9% of 584,873 suspect fever cases). An estimated 516,576 courses of inappropriate ACT prescription were averted. CONCLUSIONS: The data indicate high adherence of anti-malarial prescribing practice to RDT results after an initial run-in period. The large reduction in ACT consumption enabled by the move from symptom-based to parasite-based diagnosis demonstrates that effective roll-out and use of malaria RDTs is achievable on a national scale through well planned and structured implementation. While more detailed information on management of parasite-negative cases is required at point of care level to assess overall cost-benefits to the health sector, considerable cost-savings were achieved in ACT procurement. Programmes need to be allowed flexibility in management of these funds to address increases in other programmatic costs that may accrue from improved diagnosis of febrile disease.