Epidemiology of pertussis in a West African community before and after introduction of a widespread vaccination program

The control of pertussis remains a worldwide concern. Little has been documented about its epidemiology in Africa. The authors have studied pertussis in a prospective cohort of children in a rural West African community over a 13-year period comprising time before and after introduction of a vaccination program. Children under age 15 years who were residents of the Niakhar study area in Senegal were followed prospectively between January 1984 and December 1996 for the occurrence of pertussis. Morbidity and mortality rates were extremely high before the launch of immunization. Crude incidence was 183 per 1,000 child-years at risk under age 5 years, with a 2.8% case-fatality rate. After the introduction of the vaccination program, overall incidence dropped rapidly and dramatically-by 27% after 3 years and 46% after 6 years. The decline in incidence involved all age groups but was most substantial in the group under age 5 years and was particularly pronounced in unvaccinated infants. The median age of acquisition of the disease rose steadily with population vaccine coverage. This study shows the tremendous magnitude of the disease burden in children and the rapid decline after vaccination, and it suggests a strong herd-immunity effect.     

Critical study of an interdisciplinary survey of urinary schistosomiasis in Burkina Faso

We consider an approach to built on a score summarizing some demographic, social, geographic and parasitologic data for purpose of measuring the health impact of schistosomiasis. Operational definitions are given for the social, ecological and medical variables and for the survey design. Twenty villages from the Bam-Kongoussi district were kept for the survey, giving a sample of 11,396 peoples. The process of the survey is described. The overall response rate is 63%. The sensitivity of the survey's results in regard to the non-responses is considered along with the possibility to implement a call back survey.     

Dracunculosis: beliefs and attitudes of populations in the endemic zone of the savannah (Burkina-Faso)

For years, most of the authors propose the sinking of wells as the only method of dracunculiasis control. However, this measure did not lead to the eradication of this very vulnerable endemic scourge in West Africa. Our research has concerned the collection of epidemiologic and socio-medical data close to the housewives. The research has been carried out into six endemic villages in Burkina-Faso, North-Western savannah before the setting up of a control project through health education and chemical water supply points treatment. The global dracunculiasis incidence rate is about 20.3%, setting the six villages in hyperendemic zone. The family incidence rates are from 5.3% to 100% with an attack of 72% of families. The majority of patients are taken into account in case of disability by the village community. Causes of the illness are unknown for 68% of persons, but 30% of people associate it to the water. Ignorance and lack of treatment concern 63.5% of answers. Traditional treatment (32.8% of answers) is very diversified and based on plant extracts. As for the prevention of disease, there is no solution in 83% of cases. A part from the 35% of answers concerning modern well water, the other proposed methods are ineffective. Ponds are finally the mainly water supply source during the raining seasons in spite of the presence of modern wells. The reasons of that situation are mainly the taste of ponds water and the remoteness of wells. The understanding of those beliefs and attitudes lead to thing of several complementary strategies as sinking of modern wells and health education for dracunculiasis control.     

Cost of integrated vector control with improved sanitation and road infrastructure coupled with the use of slow-release Bacillus sphaericus granules in a tropical urban setting

A field test of integrated vector control was conducted in a tropical urban setting with a combination of a floating, slow-release, granular formulation of Bacillus sphaericus and environmental engineering measures (renovation of roads, collective water pumps, and cesspool lids). The targets were Culex quinquefasciatus and Anopheles gambiae in the two biggest towns of Burkina Faso (West Africa). Within the intervention zone, water pumping stations were improved and the surroundings drained to prevent the accumulation of stagnant water. Roads were leveled and given either simple gutters on each side or a concrete channel on one side to drain runoff water. Garbage containers were installed to provide an alternative to the drainage channels for waste disposal. Septic tanks were modified so that they could be emptied without destroying their lid. This study showed that it is possible to implement mosquito control in a tropical urban environment with teams of young people rapidly trained to apply a biological larvicide without any tools other than an iron bar to lift cesspool lids. Environmental improvements were initially costly, but demanded little subsequent expenditure. Local inhabitants' committees were mobilized to provide people with information and monitor the efficacy of the measures. Compared with what people spent individually on mosquito prevention and malaria medicine, these measures were not expensive, but many expected the community to pay for them from existing taxes, e.g., for water treatment and disposal. The necessary funding and logistics require a municipal organization with neighborhood support, if the measures are to be effective.     

Semiologic value and optimum stimuli trial during the vibratory test: results of a 3D analysis of nystagmus

Nystagmus signaling vestibular dysfunction was observed after vibratory stimulation with a 100 Hz ABC stimulator in a population of 36 patients with unilateral labyrinthine pathology (ULP) (pre and postoperative neuromas, vestibular neurectomies) and 10 patients with vestibular neuritis. The stimulus was applied on 3 bony points of the skull (vertex and 2 mastoids) and 2 muscular points of the neck (right and left posterior cervical region). These results were compared with those in 95 normal subjects and 19 cases of central disease and were correlated on the same day with results of the caloric test and head shaking test (HST). A consistent nystagmus was found in only 6 % of the normal subjects (specificity 94 %) and in 10 % of the central lesions, but in 94 % of the 36 peripheral ULP. The sensitivity of the test was equivalent to the HST. The signal was optimized in 30 patients: stimulus frequency, amplitude, stimulator mass, form of the contact, patient tolerance. The best results were obtained for a frequency of 100 Hz and an amplitude of 0.5 mm (there was no response under 0.1 mm vibration amplitude). Under videoscopy and 3D videonystagmography, the direction or side of the nystagmus was constant, but its axis (horizontal, oblique or rotational) changed according to the location of the stimulator: on the mastoid (elective location of stimulation with responses in 94 % of cases) the axis was most often horizontal or horizontal rotational. On the vertex location (where nystagmus was observed in 60 % of cases) the axis of nystagmus was most often rotational or oblique and sometimes horizontal-rotational. The nystagmus showed short latency (less than 200 ms). It started and stopped as stimulation was initiated and interrupted. Nystagmus persisted for the duration of patient tolerance. This nystagmus generally signifies unilateral vestibular weakness rather than vestibular predominance. It is a good indicator of unilateral vestibular dysfunction and could serve as a useful test in clinical practice. We discuss the origin of the nystagmus which may originate in muscle proprioception (by propagation of the vibration to neck muscles) or in the labyrinth (simultaneous excitation of 3 canals on each side).     

Efficacy, safety, and selection of molecular markers of drug resistance by two ACTs in Mali

We conducted a randomized single-blinded trial comparing the efficacy and safety of artesunate (AS) + amodiaquine (AQ, 3 days) versus AS (3 days) + sulfadoxine-pyrimethamine (SP, single dose) versus AS monotherapy (5 days) in Southern Mali. Uncomplicated malaria cases were followed for 28 days. Molecular markers of drug resistance were determined. After identification of recrudescences by genotyping, both artemisinin-based combination therapies (ACTs) reached nearly 100% efficacy at Day 14 and Day 28 versus 98.3% and 96.5% for AS, respectively (P > 0.05). AS + SP significantly selected DHFR and DHPS mutations associated with sulfadoxine and pyrimethamine resistance (P < 0.001), and AS + AQ equally selected PfCRT and PfMDR1 point mutations associated with chloroquine and AQ resistance (P < 0.001). No significant adverse event attributable to any of the study drugs was found. The ACTs were efficacious and safe, but the selection of markers for resistance to the partner drugs raises concerns over their lifespan in areas of intense malaria transmission.