Severity markers in severe leptospirosis: a cohort study.

We aimed to evaluate parameters for their value as severity markers in hospitalized leptospirosis patients. We recruited 47 informed adult consenting patients and assessed a number of clinical, hematological, biochemical, and biological variables. Patients were sorted according to severity based on fatality or the requirement of mechanical ventilation or dialysis; the parameters studied were compared between groups on inclusion and the next day. Beside septic shock presentation or a high severity score (Simplified Acute Physiology Score; SAPS II), increased lactate, total bilirubin, lipase, and AST/ALT ratio or a decreased cytokines IL-10/TNF-α ratio were all significantly associated with severity. The gene expression of the IL-1 receptor antagonist IL-1ra, IL-1α, and the long pentraxin PTX-3 were also transcribed at higher levels in most severe cases. Patients could rapidly improve or deteriorate, highlighting the need for a new assessment the next day. Our results add to the limited body of knowledge about severity markers in leptospirosis. They also suggest that patients should be reassessed the next day before being possibly discharged from the hospital. Further studies are needed in order to confirm relevant and reliable prognostic parameters in leptospirosis that would be helpful for the purpose of triage.

Klebsiella pneumoniae resistant to third-generation cephalosporins in five African and two Vietnamese major towns: multiclonal population structure with two major international clonal groups, CG15 and CG258.

The molecular epidemiology of third-generation cephalosporin-resistant (3GC-R) Klebsiella pneumoniae in developing countries is poorly documented. From February 2007 to March 2008, we collected 135 3GC-R K. pneumoniae isolates from seven major towns in Maghreb (Morocco), West Africa (Senegal, Côte d'Ivoire), Central Africa (Cameroon), East Africa (Madagascar) and Southeast Asia (Vietnam). Their genetic diversity, assessed by multilocus sequence typing, was high (60 sequence types), reflecting multiclonality. However, two major clonal groups, CG15 (n = 23, 17% of isolates) and CG258 (n = 18, 13%), were detected in almost all participating centres. The two major clonal groups have previously been described in other parts of the world, indicating their global spread. The high diversity of enterobacterial repetitive intergenic consensus sequence-PCR banding patterns at the local level indicates that most isolates were epidemiologically unrelated. The isolates were characterized by the presence of multiple resistance determinants, most notably the concomitant presence of the aac(6')-Ib-cr, qnr and blaCTX-M-15 genes in 61 isolates (45%) belonging to 31 sequence types. These isolates were detected across a large geographical area including Cameroon (n = 1), Vietnam (n = 4), Madagascar (n = 10), Côte d'Ivoire (n = 12), Morocco (n = 13) and Senegal (n = 21). These results have major implications for patient management and highlight a potential reservoir for resistance determinants.

Epidemiology of methicillin-resistant Staphylococcus aureus lineages in five major African towns: emergence and spread of atypical clones.

The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in Africa is poorly documented. From January 2007 to March 2008, we collected 86 MRSA isolates from five African towns, one each in Cameroon, Madagascar, Morocco, Niger and Senegal. Although one or two major clones, defined by the sequence type and staphylococcal cassette chromosome mec type, predominated at each site, genetic diversity (ten clones) was relatively limited in view of the large geographical area studied. Most of the isolates (n = 76, 88%) belonged to three major clones, namely ST239/241-III, a well-known pandemic clone (n = 34, 40%), ST88-IV (n = 24, 28%) and ST5-IV (n = 18, 21%). The latter two clones have only been sporadically described in other parts of the world. The spread of community-associated MRSA carrying the Panton-Valentine leukocidin genes is a cause for concern, especially in Dakar and possibly throughout Africa.

Epidemiology of methicillin-susceptible Staphylococcus aureus lineages in five major African towns: high prevalence of Panton-Valentine leukocidin genes.

The epidemiology of methicillin-susceptible Staphylococcus aureus (MSSA) in Africa is poorly documented. From January 2007 to March 2008, 555 S. aureus isolates were collected from five African towns in Cameroon, Madagascar, Morocco, Niger, and Senegal; among these, 456 unique isolates were susceptible to methicillin. Approximately 50% of the MSSA isolates from each different participating centre were randomly selected for further molecular analysis. Of the 228 isolates investigated, 132 (58%) belonged to five major multilocus sequence typing (MLST) clonal complexes (CCs) (CC1, CC15, CC30, CC121 and CC152) that were not related to any successful methicillin-resistant S. aureus (MRSA) clones previously identified in the same study population. The luk-PV genes encoding Panton-Valentine leukocidin (PVL), present in 130 isolates overall (57%), were highly prevalent in isolates from Cameroon, Niger, and Senegal (West and Central Africa). This finding is of major concern, with regard to both a source of severe infections and a potential reservoir for PVL genes. This overrepresentation of PVL in MSSA could lead to the emergence and spread of successful, highly virulent PVL-positive MRSA clones, a phenomenon that has already started in Africa.

Geographic and ecological distribution of the dengue and chikungunya virus vectors Aedes aegypti and Aedes albopictus in three major Cameroonian towns.

Aedes albopictus (Diptera: Culicidae) was first reported in Central Africa in 2000, together with the indigenous mosquito species Aedes aegypti (Diptera: Culicidae). Because Ae. albopictus can also transmit arboviruses, its introduction is a public health concern. We undertook a comparative study in three Cameroonian towns (Sahelian domain: Garoua; equatorial domain: Douala and Yaoundé) in order to document infestation by the two species and their ecological preferences. High and variable levels of pre-imaginal Ae. aegypti and Ae. albopictus infestation were detected. Only Ae. aegypti was encountered in Garoua, whereas both species were found in Douala and Yaoundé, albeit with significant differences in their relative prevalence. Peridomestic water containers were the most strongly colonized and productive larval habitats for both species. No major differences in types of larval habitat were found, but Ae. albopictus preferentially bred in containers containing plant debris or surrounded by vegetation, whereas Ae. aegypti tended to breed in containers located in environments with a high density of buildings. These findings may have important implications for vector control strategies.

Present and future schistosomiasis control activities with support from the Schistosomiasis Control Initiative in West Africa.

Since 2004 the West African countries of Burkina Faso, Mali and Niger have implemented national schistosomiasis and soil-transmitted helminthiasis control programmes with financial and technical support from the Schistosomiasis Control Initiative (SCI). In the first three years of the control programmes, nearly 13.5 million doses of praziquantel and albendazole have been administered against schistosomiasis and soil-transmitted helminthiasis with coverage rates varying between 67.0% and 93.9%. These treatments have resulted in a reduction of the prevalence and intensity of Schistosoma infection in the sentinel cohorts that were set up to monitor and evaluate the national control programmes. The challenges currently faced by these national control programmes are the ability to maintain the reduction in morbidity achieved thus far due to the mass treatment campaigns and ensuring sustainability. For reinforcement of surveillance, the establishment of a geographical information system is suggested in order to contribute towards enhanced sustainability of these programmes. Our new working hypothesis is that targeted control accompanied by periodic mass treatment campaigns (every two to three years) can contribute to maintaining the low levels of morbidity achieved thus far. The implementation of integrated neglected tropical disease control programmes in these countries will provide means to ensure the financial sustainability of control activities for the years to come.

Field evaluation of rapid diagnostic tests for meningococcal meningitis in Niger.

OBJECTIVE: To evaluate dipstick rapid diagnostic tests (RDTs) for meningococcal meningitis in basic health facilities. METHODS: Health facility staff received a one-day training. During the meningitis season, they performed RDTs on cerebrospinal fluid (CSF) specimens from suspected cases of meningitis. A frozen aliquot of CSF was later tested using polymerase chain reaction (PCR) to establish the reference diagnosis. RDTs used in health facilities were archived to allow checking the concordance between reported diagnosis and observed results. Reported diagnosis was also compared to PCR diagnosis. A second RDT was performed on each CSF specimen at the reference laboratory. RESULTS: Using RDTs, health facilities reported 382 negative results (73.9%), 114 NmA (22.1%), 12 NmW135 (2.3%) and nine uninterpretable results (1.7%), the latter corresponding to the misuse of a reagent by three agents. The agreement between reported diagnosis and archived dipsticks was excellent (kappa = 0.98). The agreement between PCR diagnosis and reported RDTs results was strong (kappa = 0.82). In health facilities, the sensitivity of RDTs for N. meningitidis A was Se = 0.91. The kappa coefficient measuring the agreement between RDTs operated in the reference laboratory and RDTs operated in health facilities was kappa = 0.78. CONCLUSION: We confirmed that dipstick RDTs to identify N. meningitidis serogroups A, C, W135 and Y can be reliably operated by non-specialized staff in basic health facilities. RDTs proved very useful to recommend vaccination in NmA epidemics, and also to avoid vaccination in epidemics due to serogroups not included in vaccines (NmX).

[Illicit drug trade on the markets of Yaounde (Cameroon) and Niamey (Niger): characteristics of salesmen and quality of drugs]. / Le circuit informel des médicaments à Yaoundé et à Niamey: étude de la population des vendeurs et de la qualité des médicaments distribués.

This study characterizes salesmen and evaluates the drugs offer and quality of the drugs in the illicit selling network in Yaoundé (Cameroon) and Niamey (Niger). A sample of 75 and 124 drug salesmen working in these cities was questioned using a standardized questionnaire. The prescription of drugs and the advices provided by these poorly trained salesmen could have an important impact in term of public health: 32% and 67% of the salesmen in Yaoundé give systematically or occasionally advices regarding the prescription. The active substances are always present in the 153 drugs of our analysed sample, except for chloroquine-based drugs, among which 5/30 samples did not contain active substance. However, the rate of nonconformity is approximately 50% in the two cities. Complementary studies are needed to explore the origin of these nonconformities, between counterfeiting, low quality of the products provided by the factories, defects of conservation or instability of the formulations.

[Prevalence of tuberculous meningitis in Niamey's Hospital, Niger]. / Prevalence de la méningite tuberculeuse a l'hôpital de Niamey, Niger.

Tuberculosis is hyperendemic in Niger. In Niamey between June 2002 and May 2004, 996 cerebro-spinal fluids (CSF) collected from meningitis suspected patients have been analysed by PCR for the detection of Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae: the aetiologic diagnosis was obtained for 208 cases (20.9%). The Mycobacterium tuberculosis PCR assay performed on the negative samples was positive for 4 CSF: 0.4% prevalence among suspected cases of meningitis or 1.9% among confirmed bacterial meningitis.

Evaluation of the Pastorex meningitis kit for the rapid identification of Neisseria meningitidis serogroups A and W135.

The recent emergence of Neisseria meningitidis W135 as a cause of epidemic bacterial meningitis and the availability of a trivalent ACW135 vaccine have created a need for accurate and timely meningococcal serogroup determination for organization of epidemic vaccine response. The sensitivity and specificity of the Pastorex meningitis kit (Bio-Rad) to identify serogroups A and W135 in the African meningitis belt was assessed using PCR testing as the gold standard. The sensitivity and specificity for serogroups A and W135 were 87 and 85%, respectively, while the specificities were 93 and 97%. The positive and negative likelihood ratios for A were 12 and 0.14 and for W135 were 33 and 0.16. The positive and negative predictive values, computed to simulate an epidemic of meningococcal meningitis with an estimated 70% prevalence of N. meningitidis among suspected cases, were 97% and 75% for A and 99% and 73% for W135. In remote locations of the African meningitis belt, latex agglutination is the only currently available test that can rapidly determine meningococcal serogroup. This study showed that latex agglutination performs well and could be used during the epidemic season to determine appropriate vaccine response.

Molecular epidemiology of meningococci isolated in Niger in 2003 shows serogroup A sequence type (ST)-7 and serogroup W135 ST-11 or ST-2881 strains.

In 2003, in the Zinder and Maradi regions (Niger), epidemics were due to serogroup A:4:P1.9 meningococci belonging to sequence type 7 (ST-7). In Niamey, only sporadic cases were reported: 55% of the meningococcus strains were in serogroup A, and 38% were in serogroup W135 and could be placed in ST-11, identical to the 2002 Burkina Faso epidemic clone, and in ST-2881, a new ST.

Nationwide HIV prevalence survey in general population in Niger.

A national population-based survey was carried out in Niger in 2002 to assess HIV prevalence in the population aged 15-49 years. A two-stage cluster sampling was used and the blood specimens were collected on filter paper and tested according to an algorithm involving up to three diagnostic tests whenever appropriate. Testing was unlinked and anonymous. The refusal rate was 1.1% and 6056 blood samples were available for analysis. The adjusted prevalence of HIV was 0.87% (95% CI, 0.5-1.3%) and the 95% CI of the estimated number of infected individuals was 22 864-59 640. HIV-1 and HIV-2 represented, respectively, 95.6% and 2.9% of infections while dual infections represented 1.5%. HIV positivity rate was 1.0% in women and 0.7% in men. It was significantly higher among urban populations than among rural ones (respectively, 2.1% and 0.6%, P < 10(-6)). Using logistic regression, the variables significantly related to the risk of being tested positive for HIV were urban housing, increasing age and being either widowed or divorced. The estimate from the national survey was lower than the prevalence assessed from antenatal clinic data (2.8% in 2001). In the future, the representativeness of sentinel sites should be improved by increasing the representation of rural areas accounting for more than 80% of the population. Compared with other sub-Saharan countries, the HIV prevalence in Niger is still moderate. This situation represents a strong argument for enhancing prevention programmes and makes realistic the projects promoting an access to potent antiretroviral therapies for the majority.

Lot quality assurance sampling for screening communities hyperendemic for Schistosoma mansoni.

Lot quality assurance sampling (LQAS) was evaluated for rapid low cost identification of communities where Schistosoma mansoni infection was hyperendemic in southern Madagascar. In the study area, S. mansoni infection shows very focused and heterogeneous distribution requiring multifariousness of local surveys. One sampling plan was tested in the field with schoolchildren and several others were simulated in the laboratory. Randomization and stool specimen collection were performed by voluntary teachers under direct supervision of the study staff and no significant problem occurred. As expected from Receiver Operating Characteristic (ROC) curves, all sampling plans allowed correct identification of hyperendemic communities and of most of the hypoendemic ones. Frequent misclassifications occurred for communities with intermediate prevalence and the cheapest plans had very low specificity. The study confirmed that LQAS would be a valuable tool for large scale screening in a country with scarce financial and staff resources. Involving teachers, appeared to be quite feasible and should not lower the reliability of surveys. We recommend that the national schistosomiasis control programme systematically uses LQAS for identification of communities, provided that sample sizes are adapted to the specific epidemiological patterns of S. mansoni infection in the main regions.

Relationship between parasite density and fever risk in a community exposed to a low level of malaria transmission in Madagascar highlands.

To establish a simple definition of a malaria attack based on blood parasite density and other explanatory covariates, a cohort study was conducted from 1993 to 1996 in the Madagascar highlands undergoing a low seasonal transmission of falciparum malaria. Using logistic regression, the explanatory variables found to be significantly related to the risk of fever are parasite density, age, season, and year. However, and in contrast with other studies, we found no evidence of a clear cutoff in parasite density values consistent with the concept of "pyrogenic threshold" despite a gradual increase of the risk of fever with increasing parasite density. Furthermore, the model evidenced an individual-dependent relationship at a given age. This point was in accordance with the immunological data recorded from the participants. The investigators conclude that the parasite density to distinguish malaria attacks from other causes of fever is not reliable in a context of low falciparum transmission.

Mass vaccination campaigns to eradicate poliomyelitis in Madagascar: oral poliovirus vaccine increased immunity of children who missed routine programme.

To assess the impact of mass vaccination campaigns using oral poliovirus vaccine (OPV) in Madagascar, serum neutralizing antibodies and geometrical mean titres (GMTs) to poliovirus were measured among 472 children aged up to 59 months, before and after the mass campaign, regardless of their previous history of routine vaccination. In this study, overall coverage with three routine and two mass campaign OPV doses was 69.9 and 93.4%, respectively. Seroprevalences to all poliovirus types were significantly higher after the mass campaign among the children who were not vaccinated through routine programme: 67.5% vs. 90.2% (P < 0.001) for type 1; 66.7% vs. 95.1% (P < 0.001) for type 2; and 55.3% vs. 82.9% (P < 0.001) for type 3. Geometrical mean titres to all poliovirus types also significantly increased after the mass campaign among the same study group: 34.5 vs. 238.9 (P < 0.001) for type 1; 35.1 vs. 402.6 (P < 0.001) for type 2; and 13.3 vs. 92.6 (P < 0.001) for type 3. Post-mass campaign seroprevalences and GMTs for poliovirus, especially types 1 and 3, among children who received up to two routine and two mass campaign OPV doses were significantly higher than pre-mass campaign seroprevalences among children who received three routine OPV doses. Reasons for lack of adherence to the vaccination programme and the mass campaign are discussed. The findings strongly support the WHO strategy of conducting mass campaign in all endemic countries. However, as the mass campaign strategy now has been discontinued, it is crucial to increase the routine coverage and to improve acute flaccid paralysis surveillance in order to fulfil the goal of poliomyelitis eradication.

Geographic differences in hepatosplenic complications of schistosomiasis mansoni and explanatory factors of morbidity.

In a study in three neighbouring villages of southern Madagascar, where Schistosoma mansoni is hyperendemic, ultrasound examination using the Niamey protocol showed marked differences in the burden of disease from one village to another. Hepatosplenic schistosomiasis was more frequent in the village with the highest geometric mean egg counts and the earliest onset of infections, demonstrating that the morbidity induced by S. mansoni may vary greatly within a given area. True representativeness of study populations, a keystone of epidemiological studies, is mandatory to obtain a clear picture of a wide area. Ultrasound examinations in a small number of villages, or even a single one, may be a questionable approach. Using logistic regression analysis, the explanatory variables found to be significantly associated with a risk of severe hepatosplenic disease in our study were sex, age, village of residence and S. mansoni egg counts. On the other hand, a concurrent infection with an intestinal helminth seems to reduce the risk of severe hepatosplenic disease. Further studies should assess the role and possible impact of intestinal helminths on S. mansoni associated-morbidity.

Validity of Lot Quality Assurance Sampling to optimize falciparum malaria surveys in low-transmission areas.

To control the reappearance of malaria in the Madagascan highlands, indoor house-spraying of DDT was conducted from 1993 until 1998. Before the end of the insecticide-spraying programme, a surveillance system was set up to allow rapid identification of new malaria epidemics. When the number of suspected clinical malaria cases notified to the surveillance system exceeds a predetermined threshold, a parasitological survey is carried out in the community to confirm whether or not transmission of falciparum malaria is increasing. Owing to the low specificity of the surveillance system, this confirmation stage is essential to guide the activities of the control programme. For this purpose, Lot Quality Assurance Sampling (LQAS), which usually requires smaller sample sizes, seemed to be a valuable alternative to conventional survey methods. In parallel to a conventional study of Plasmodium falciparum prevalence carried out in 1998, we investigated the ability of LQAS to rapidly classify zones according to a predetermined prevalence level. Two prevalence thresholds (5% and 15%) were tested using various sampling plans. A plan (36, 2), meaning that at least 2 individuals found to be positive among a random sample of 36, enabled us to classify a community correctly with a sensitivity of 100% and a specificity of 94%. LQAS is an effective tool for rapid assessment of falciparum malaria prevalence when monitoring malaria transmission.

Malaria in the highlands of Madagascar after five years of indoor house spraying of DDT.

The central region of Madagascar is a vast area of highlands (altitude 700-2000 m). Malaria transmission has re-established itself here since the last epidemic of 1985-90 and has caused the deaths of 40,000 persons according to the Minister of Health. To combat the main malaria vector in the region, Anopheles funestus, annual programmes of indoor house spraying of DDT were carried out between December 1993 and January 1998 in most rural areas at altitude 1000-1500 m. A parasitological and serological study was then conducted in the highland schools to evaluate the impact of the programme and set up a database on the region. Using a cluster-sampling method 2 independent selections were conducted (one of 130 sites, the other of 40 sites). During the study, 13,462 schoolchildren were examined, 71% living in sprayed villages. Parasite prevalence among schoolchildren declined as altitude increases, from 11% at 700-900 m to 0.4% at > 1500 m. Below 1500 m, the impact of the spraying on the prevalence of the parasite was very clear (an average decrease of from 20% to 2.7% below 1000 m and of from 4.5% without spraying to 0.8% at 1000-1500 m). Geographical analysis of the data showed that the marginal regions remained the most affected by malaria (especially outside spraying zones), and persistence of 'pockets of transmission' at 1000-1500 m, essentially in areas where spraying has never been used. In 9 schools, anti-Plasmodium antibodies were sought by indirect immunofluorescence on thick smears of parasitized red blood cells. The seroprevalence ranged from 22% to 63%, which suggests that the parasite is still circulating in the region. Even though our data show that vector control continues to be very successful in the Madagascan highlands, rapid reinfection could occur and must be monitored following spraying. To this end, the Minister for Health, with the support of the Italian Co-operation, has placed the region under epidemiological surveillance since 1997. An alert system for the timely detection of the sources of epidemics and the targeting of the antivectoral campaign is also in operation. Our study suggests that this strategy should be reinforced by the spraying of DDT in the marginal zones in order to consolidate the results obtained at higher altitudes.