Effects of long working hours and the night shift on severe sleepiness among workers with 12‐hour shift systems for 5 to 7 consecutive days in the automobile factories of Korea

We investigated the effects of 12‐hour shift work for five to seven consecutive days and overtime on the prevalence of severe sleepiness in the automobile industry in Korea. [Correction added after online publication 28 Nov: Opening sentence of the summary has been rephrased for better clarity.] A total of 288 randomly selected male workers from two automobile factories were selected and investigated using questionnaires and sleep‐wake diaries in South Korea. The prevalence of severe sleepiness at work [i.e. Karolinska Sleepiness Scale (KSS) score of 7 or higher] was modeled using marginal logistic regression and included theoretical risk factors related to working hours and potential confounding factors related to socio‐economic status, work demands, and health behaviors. Factors related to working hours increased the risk for severe sleepiness at the end of the shift in the following order: the night shift [odds ratio (OR): 4.7; 95% confidence interval (CI): 3.6–6.0)], daily overtime (OR: 2.2; 95% CI: 1.7–2.9), weekly overtime (OR: 1.6; 95% CI: 1.0–2.6), and night overtime (OR: 1.6; 95% CI: 0.8–3.0). Long working hours and shift work had a significant interactive effect for severe sleepiness at work. Night shift workers who worked for 12 h or more a day were exposed to a risk of severe sleepiness that was 7.5 times greater than day shift workers who worked less than 11 h. Night shifts and long working hours were the main risk factors for severe sleepiness among automobile factory workers in Korea. Night shifts and long working hours have a high degree of interactive effects resulting in severe sleepiness at work, which highlight the need for immediate measures to address these characteristics among South Korean labor force patterns.     

Ultrasonographic aspects of urinary schistosomiasis in children of the Dogon plateau and the Niger office; impact of praziquantel treatment

Urinary bilharziasis is a parasitic infection responsible for vesical, urethral and renal lesions. The authors demonstrate the importance of ambulatory echography on a large scale and describe various echographic lesions. Vesical attacks occurred in 27% of the wall irregularity, 44% of the masses and polyps. Pyelic and urethral abnormalities occurred in 16.6% and 29.9% of cases respectively at the baseline in 1991. These prevalence rates decreased after seven years, in 1998. The authors discuss the utility of chemotherapy with praziquantel and the necessity of a periodical mass treatment in the areas with high bilharziasis endemicity in Mali.     

Urinary disease in 2 Dogon populations with different exposure to Schistosoma haematobium infection: progression of bladder and kidney diseases in children and adults

BACKGROUND: Schistosoma haematobium infection causes severe urinary disease and considerable mortality. The factors that determine disease progression from mild to severe stages are not fully understood. METHODS: Here we describe a cross-sectional epidemiological study of kidney and bladder diseases in 2 Dogon populations with different exposure to S. haematobium infection. RESULTS: Early and high exposure resulted in more-severe disease, especially among young subjects, without clear evidence of a more-rapid development of immunity. Nevertheless, 50%-60% of subjects of all age classes in both villages showed no evidence of disease. Kidney and bladder disease peaked biphasically among young subjects and adults >25 years old. The first peak corresponded with infections of maximum intensity, whereas the second peak occurred among adults with infections of very low intensity. Kidney disease was correlated with circulating anodic antigen concentration in serum, whereas bladder disease was correlated with egg count and eosinophil cationic protein concentration in urine. Kidney and bladder disease did not correlate. Severe kidney disease was more frequent in certain families. CONCLUSIONS: The frequency of urinary disease is increased by infections acquired early during life, is regulated by strong clinical immunity in certain subjects, and may be dependent on hereditary factors. Kidney and bladder disease may involve different mechanisms of pathogenesis, which may differ between children and adults.     

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.     

A high malaria reinfection rate in children and young adults living under a low entomological inoculation rate in a periurban area of Bamako,Mali

In areas of intense malaria parasite transmission, preliminary studies of the rate of reinfection after curative therapy suggest that small sample size studies of vaccine efficacy are feasible. However, the effect of transmission rate, which may vary considerably between transmission seasons, on reinfection rate has not been assessed in areas of mesoendemicity with seasonal transmission. To address this question, the Plasmodium falciparum reinfection rate after curative therapy was measured in Sotuba, a Malian village with historically low transmission rates, as estimated by the entomological inoculation rate (EIR). The reinfection rate after curative Fansidar (sulfadoxine-pyrimethamine) treatment was 80.7% (88/109). The EIR during the 13-week study period (seasonal transmission) varied between 1 and 4.5 infected bites/person/month. The finding that reinfection rates were high despite low EIRs suggests that a low EIR may be sufficient to support small sample size vaccine efficacy trials in mesoendemic areas.     

Season, fever prevalence and pyrogenic threshold for malaria disease definition in an endemic area of Mali

BACKGROUND: Modelling malaria parasitaemia as function of fever has been proposed as best alternative to estimate the attributable fraction of malaria fever and the sensitivity and specificity of different case definitions of malaria disease. OBJECTIVES: To determine the prevalence of fever and its relation to malaria parasitaemia and to establish a pyrogenic threshold for malaria disease in the area. METHODS: We conducted two cross-sectional surveys in children of 6 months to 9 years of age (2434 during the rainy season of 1993 and 2353 during the dry season of 1994) randomly selected from 21 areas of Bandiagara district, Mali. RESULTS: The relationship between fever and Plasmodium falciparum parasitaemia depends strongly on the season, thus affecting the malaria-attributable fraction of fever cases and the sensitivity and specificity of malaria case definitions. The overall proportion of fever attributable to malaria parasitaemia was 33.6% during the rainy season and 23.3% during the dry season, with the highest proportion occurring among the youngest children. The cut-off value, where the sensitivity curve crosses the specificity curve, was around 3200 pf/microl for all age categories during the rainy season and 200 pf/microl during the dry season. CONCLUSIONS: Malaria remains a main cause of fever in this area of Mali. The pyrogenic threshold of parasitaemia depends strongly on the season, and different cut-off levels of parasitaemia should be used during the two seasons to define malaria cases in this area.     

Fréquence du déficit en glucose-6-phosphate déshydrogénase (A-376/202) dans trois groupes ethniques vivant en zone d’endémie palustre au Mali

Erythrocyte G6PD deficiency is the most common worldwide enzymopathy. The aim of this study was to determine erythrocyte G6PD deficiency in 3 ethnic groups of Mali and to investigate whether erythrocyte G6PD deficiency was associated to the observed protection against malaria seen in Fulani ethnic group. The study was conducted in two different areas of Mali: in the Sahel region of Mopti where Fulani and Dogon live as sympatric ethnic groups and in the Sudanese savannah area where lives mostly the Malinke ethnic group. The study was conducted in 2007 in Koro and in 2008 in Naguilabougou. It included a total 90 Dogon, 42 Fulani and 80 Malinke ethnic groups. Malaria was diagnosed using microscopic examination after Giemsa-staining of thick and thin blood smear. G6PD deficiency (A-^376/202) samples were identified using RFLP (Restriction Fragment Length Polymorphism) assay and analysis of PCR-amplified DNA amplicon. G6PD deficiency (A-^376/202) rate was 11.1%, 2.4%, and 13.3% in Dogon, Fulani, and Malinke ethnic group respectively. Heterozygous state for G6PD (A-^376/202) was found in 7.8% in Dogon; 2.4% in Fulani and 9.3% in Malinke ethnic groups while hemizygous state was found at the frequency of 2.2% in Dogon and 4% in Malinke. No homozygous state was found in our study population.We conclude that G6PD deficiency is not differing significantly between the three ethnic groups, Fulani, Dogon and Malinke.     

Repeated artemisinin-based combination therapies in a malaria hyperendemic area of Mali: efficacy, safety, and public health impact

Artemisinin-based combination therapies (ACTs) are the first-line treatment of uncomplicated malaria. The public health benefit and safety of repeated administration of a given ACT are poorly studied. We conducted a randomized trial comparing artemether-lumefantrine, artesunate plus amodiaquine (AS+AQ) and artesunate plus sulfadoxine-pyrimethamine (AS+SP) in patients 6 months of age and older with uncomplicated malaria in Mali from July 2005 to July 2007. The patient received the same initial treatment of each subsequent uncomplicated malaria episode except for treatment failures where quinine was used. Overall, 780 patients were included. Patients in the AS+AQ and AS+SP arms had significantly less risk of having malaria episodes; risk ratio (RR) = 0.84 (P = 0.002) and RR = 0.80 (P = 0.001), respectively. The treatment efficacy was similar and above 95% in all arms. Although all drugs were highly efficacious and well tolerated, AS+AQ and AS+SP were associated with less episodes of malaria.     

In vitro cultivation of fields isolates of Plasmodium falciparum in Mali

Malaria immunology, molecular biology and pathogenicity studies often require the adaptation of Plasmodium falciparum field isolates to continuous in vitro cultivation. For this purpose we have established propagation protocols of asexual erythrocytic stages of P. falciparum samples from malaria patients or asymptomatic carriers in Mali. The parasites were grown in standard culture medium supplemented by human serum and in a culture medium without human serum but supplemented by AlbuMax 1. The candle jar environment and tissue culture flasks gassed with 5% CO2, 5% O2 and 90% N2 obtained from a portable gas mixer were used. Protocols for parasite cultivation in a resource-poor setting were developed. These protocols were successfully applied to fresh isolates in Mali as well as to blood samples frozen in liquid nitrogen and shipped to a laboratory in U.S.A.