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Health Centre Surveys as a Potential Tool for Monitoring Malaria Epidemiology by Area and over Time
Abraham R. Oduro, Kalifa A. Bojang, David J. Conway, Tumani Corrah, Brian M. Greenwood, David Schellenberg
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0026305
Abstract: Background Presently, many malaria control programmes use health facility data to evaluate the impact of their interventions. Facility-based malaria data, although useful, have problems with completeness, validity and representativeness and reliance on routinely collected health facility data might undermine demonstration of the magnitude of the impact of the recent scaleups of malaria interventions. To determine whether carefully conducted health centre surveys can be reliable means of monitoring area specific malaria epidemiology, we have compared malaria specific indices obtained from surveys in health centres with indices obtained from cross-sectional surveys conducted in their catchment communities. Methods A series of age stratified, seasonal, cross-sectional surveys were conducted during the peak malaria transmission season in 2008 and during the following dry season in 2009 in six ecologically diverse areas in The Gambia. Participants were patients who attended the health centres plus a representative sample from the catchment villages of these health facilities. Parasitaemia, anaemia, attributable proportion of fever and anti-MSP1-19 antibody seroprevalence were compared in the health facility attendees and community participants. Results A total of 16,230 subjects completed the study; approximately half participated in the health centre surveys and half in the wet season surveys. Data from both the health centre and community surveys showed that malaria endemicity in The Gambia is now low, heterogeneous and seasonal. In the wet season, parasitaemia, seroprevalence and fever prevalence were higher in subjects seen in the health centres than in the community surveys. Age patterns of parasitaemia, attributable proportions of fever and seroprevalence rates were similar in subjects who participated in the community and health centre surveys. Conclusion Health centre surveys have potential as a surveillance tool for evaluating area specific malaria control activities and for monitoring changes in local malaria epidemiology over time.
Exogenous re-infection by a novel Streptococcus pneumoniae serotype 14 as a cause of recurrent meningitis in a child from The Gambia
Martin Antonio, Claire Oluwalana, Ousman Secka, Tumani Corrah, Stephen Howie, Richard A Adegbola
Annals of Clinical Microbiology and Antimicrobials , 2009, DOI: 10.1186/1476-0711-8-3
Abstract: Pneumococcal meningitis is common within the African meningitis belt and occurs in a seasonal pattern indistinguishable from that of meningococcal meningitis [1]. Streptococcus pneumoniae can be subdivided by serological typing based on the capsular polysaccharide protein into at least 91 different serotypes [2] the majority of which rarely cause disease. S. pneumoniae serotype14 is a common cause of severe pneumococcal disease in The Gambia and ranks first among 127 pediatric invasive isolates recently tested during a 9-valent pneumococcal conjugate vaccine trial in The Gambia [3]. S. pneumoniae serotype14 has also been associated with meningitis outbreaks in Ghana [4] and Niger [5]. The World Health Organisation recommends the use of the 7-valent pneumococcal conjugate vaccine [6] which contains serotype 14, but this is not yet available for routine use in Africa including The Gambia. Multilocus sequence typing (MLST) is a well-established method that has been used to assess the population structure of S. pneumoniae during vaccine studies in The Gambia [3]. This report describes the use of MLST to demonstrate exogenous re-infection as a cause of recurrent meningitis in a child from The Gambia.A six months old female of the Manjago tribe, from a peri-urban coastal village in The Gambia was referred from a primary health care facility and admitted to the Royal Victoria Teaching Hospital, Banjul on 6th December 2007 with clinical signs suggestive of meningitis. This diagnosis was confirmed by microscopic examination of the cerebrospinal fluid (CSF), which revealed gram-positive cocci and leucocytosis. The child was clinically successfully treated with intravenous ceftriaxone (100 mg/kg body weight daily for 13 days), during which S. pneumoniae was isolated from the CSF, subsequently identified as serotype 14 using methods described previously [7]. No neurological sequelae were evident after this episode. On 3rd January 2008, the same child was re-admitted to the Medi
Health seeking behaviour, health system experience and tuberculosis case finding in Gambians with cough
Yaya Kasse, Momodou Jasseh, Tumani Corrah, Simon A Donkor, Martin Antonnio, Adama Jallow, Richard A Adegbola, Philip C Hill
BMC Public Health , 2006, DOI: 10.1186/1471-2458-6-143
Abstract: During a round of a population under 3-monthly demographic surveillance, we identified people >10 years old who had been coughing ≥ 3 weeks. A questionnaire was administered concerning demographic data, cough, knowledge, health seeking, and experience at health facilities. Case finding utilised sputum smear and chest X-ray.122/29,871 coughing individuals were identified. Of 115 interviewed, 93 (81%) had sought treatment; 76 (81.7%) from the health system. Those that visited an alternative health provider first were significantly older than those who visited the health system first (p = 0.03). The median time to seek treatment was 2 weeks (range 0 – 106). 54 (58.1%) made their choice of provider because they believed it was right. Of those who left the health system to an alternative provider (n = 13): 7 believed it was the best place, 3 cited cost and 2 failure to improve. 3 cases were identified by sputum analysis, 11 more by X-ray; all had visited the health system first. Total 'excess' cough time was 1079 person weeks.The majority of people with cough in this population seek appropriate help early. Improved case detection might be achieved through the use of chest X-ray in addition to sputum smear.Tuberculosis (TB) causes approximately 2 million deaths per year[1]. 98% occur in low-income countries[2]. Directly observed therapy (DOTS), the main strategy for TB control globally, relies on self-presentation of adults from the community and sputum smear for diagnosis. In certain populations, even in the presence of substantial drug-resistance, it is highly effective at reducing M. tuberculosis transmissio[3]. However, in Africa, despite considerable DOTS expansion, the incidence rate is rising by approximately 6% per year[4]. While high rates of HIV infection have contributed to this[5], other factors should be considered, such as the level of understanding of TB in the community, health-seeking behaviour and health system performance.In The Gambia, which has implem
Mixed Infection with cagA Positive and cagA Negative Strains of Helicobacter pylori Lowers Disease Burden in The Gambia
Ousman Secka, Martin Antonio, Douglas E. Berg, Mary Tapgun, Christian Bottomley, Vivat Thomas, Robert Walton, Tumani Corrah, Julian E. Thomas, Richard A. Adegbola
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0027954
Abstract: Background The prevalence of Helicobacter pylori including strains with putatively virulent genotypes is high, whereas the H. pylori-associated disease burden is low, in Africa compared to developed countries. In this study, we investigated the prevalence of virulence-related H. pylori genotypes and their association with gastroduodenal diseases in The Gambia. Methods and Findings DNA extracted from biopsies and H. pylori cultures from 169 subjects with abdominal pain, dyspepsia or other gastroduodenal diseases were tested by PCR for H. pylori. The H. pylori positive samples were further tested for the cagA oncogene and vacA toxin gene. One hundred and twenty one subjects (71.6%) were H. pylori positive. The cagA gene and more toxigenic s1 and m1 alleles of the vacA gene were found in 61.2%, 76.9% and 45.5% respectively of Gambian patients harbouring H. pylori. There was a high prevalence of cagA positive strains in patients with overt gastric diseases than those with non-ulcerative dyspepsia (NUD) (p = 0.05); however, mixed infection by cagA positive and cagA negative strains was more common in patients with NUD compared to patients with gastric disease (24.5% versus 0%; p = 0.002). Conclusion This study shows that the prevalence of H. pylori is high in dyspeptic patients in The Gambia and that many strains are of the putatively more virulent cagA+, vacAs1 and vacAm1 genotypes. This study has also shown significantly lower disease burden in Gambians infected with a mixture of cag-positive and cag-negative strains, relative to those containing only cag-positive or only cag-negative strains, which suggests that harbouring both cag-positive and cag-negative strains is protective.
Highly Accurate Diagnosis of Pleural Tuberculosis by Immunological Analysis of the Pleural Effusion
Jayne S. Sutherland, Danlani Garba, Augustin E. Fombah, Awa Mendy-Gomez, Francis S. Mendy, Martin Antonio, John Townend, Readon C. Ideh, Tumani Corrah, Martin O. C. Ota
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030324
Abstract: Pleural TB is notoriously difficult to diagnose due to its paucibacillary nature yet it is the most common cause of pleural effusions in TB endemic countries such as The Gambia. We identified both cellular and soluble biomarkers in the pleural fluid that allowed highly accurate diagnosis of pleural TB compared to peripheral blood markers. Multi-plex cytokine analysis on unstimulated pleural fluid showed that IP-10 resulted in a positive likelihood ratio (LR) of 9.6 versus 2.8 for IFN-γ; a combination of IP-10, IL-6 and IL-10 resulted in an AUC of 0.96 and positive LR of 10. A striking finding was the significantly higher proportion of PPD-specific IFN-γ+TNF-α+ cell population (PPD-IGTA) in the pleural fluid compared to peripheral blood of TB subjects. Presence of this pleural PPD-IGTA population resulted in 95% correct classification of pleural TB disease with a sensitivity of 95% and specificity of 100%. These data suggest that analysis of the site of infection provides superior diagnostic accuracy compared to peripheral blood for pleural TB, likely due to the sequestration of effector cells at this acute stage of disease.
A Gambian Infant with Fever and an Unexpected Blood Film
Stephen Howie ,Malcolm Guy,Louise Fleming,Wendi Bailey,Harry Noyes,Joseph Axel Faye,Jacques Pepin,Brian Greenwood,Hilton Whittle,David Molyneux,Tumani Corrah
PLOS Medicine , 2006, DOI: 10.1371/journal.pmed.0030355
PCR-based genotyping of Helicobacter pylori of Gambian children and adults directly from biopsy specimens and bacterial cultures
Ousman Secka, Martin Antonio, Mary Tapgun, Douglas E Berg, Christian Bottomley, Vivat Thomas, Robert Walton, Tumani Corrah, Richard A Adegbola, Julian E Thomas
Gut Pathogens , 2011, DOI: 10.1186/1757-4749-3-5
Abstract: Virulence genes were amplified in 127 of 190 cases tested (121 adults and 6 children); each of 60 bacterial cultures, and 116 from DNA extracted directly from biopsies. The proportion of biopsies that were cagA+, the ratio of vacAs1/s2, and vacAm1/m2, and the proportion of mixed strain populations in individual subjects changed with age. Strains lacking virulence cagA and vacA genes and with apparently homogeneous (one predominant strain) infections were more common among infants than adults.In order to detect the range of bacterial genotypes harbored by individual patients, direct PCR proved slightly superior to isolation of H. pylori by biopsy culture, but the techniques were complementary, and the combination of both culture and direct PCR produced the most complete picture. The seemingly higher virulence of strains from adult than infant infections in The Gambia merits further analysis.Helicobacter pylori chronically infects over 50% of people worldwide, causes gastritis and sometimes gastric or duodenal ulceration, and increases the risk of gastric cancer [1,2]. Infection also contributes to other maladies such as malnutrition among the very poor, iron deficiency anemia, and susceptibility to other food and water borne pathogens, especially in developing countries, including The Gambia [3,4]. The prevalence of H. pylori infection is particularly high in developing countries including The Gambia [5-7]. H. pylori, because it is a fastidious micro-aerobic bacterium, it is technically difficult to grow and maintain for molecular biologic research in poorly resourced laboratories in Africa. These challenges coupled with the uniqueness of genotypes of African strains and special features of human physiology and environment in this continent limit our understanding of the spectrum of H. pylori-associated diseases and how this is affected by bacterial genotype in Africa [8,9]. So extensive efforts have been made to determine an optimum method for PCR-based genotyping o
Bacteraemia in patients admitted to an urban hospital in West Africa
Philip C Hill, Charles O Onyeama, Usman NA Ikumapayi, Ousman Secka, Samuel Ameyaw, Naomi Simmonds, Simon A Donkor, Stephen R Howie, Mary Tapgun, Tumani Corrah, Richard A Adegbola
BMC Infectious Diseases , 2007, DOI: 10.1186/1471-2334-7-2
Abstract: Between November 2003 and February 2005 we studied those admitted to the Medical Research Council hospital who were suspected of having bacteraemia. We documented clinical features, outcome, pathogens identified and their susceptibility patterns, and searched for factors associated with bacteraemia.871 patients were admitted and had a blood culture taken. The median age was 2 years (range 2 months to 80 years) and 36 of 119 tested were HIV positive; 54.5% were male. 297 (34%) had a positive result and 93 (10.7% overall) were considered a genuine pathogen. Those with bacteraemia were more likely to die in hospital (OR 2.79; 1.17–6.65, p = 0.017) and to have a high white cell count (WCC; OR 1.81;95% CI 1.09–3.02; p = 0.022). Three organisms accounted for 73% of bacteraemias: Streptococcus pneumoniae (45.2%), Staphylococcus aureus (18.3%) and Escherichia coli (9.7%) while non-typhoidal salmonellae (NTS) accounted for 8.6%. Antimicrobial susceptibility of S. pneumoniae was very high to penicillin (97.5%); high resistance was found to co-trimoxazole. S. aureus was generally highly susceptible to cloxacillin, gentamicin and chloramphenicol. E. coli and NTS were all susceptible to ciprofloxacin and mostly susceptible to gentamicin. Thirteen (33%) S. pneumoniae isolates were of serotypes contained in a 7-valent pneumococcal conjugate vaccine and 20 (51.3%) were of the same serogroup.In The Gambia, those with bacteraemia are more likely than those without to die in hospital and to have a raised peripheral blood WCC. S. pneumoniae is the most common organism isolated. Introduction of a pneumococcal conjugate vaccine can be expected to lead to a reduction in disease incidence.There is a large excess of mortality in sub-Saharan Africa, particularly in children: under 5 year old mortality rates of 100–250 per 1,000 compare with 10–30 per 1,000 in developed countries [1]. It is increasingly clear that invasive bacterial infections are a major contributor to this excess [2], with
Comparative evaluation of BACTEC MGIT 960 with BACTEC 9000 MB and LJ for isolation of mycobacteria in The Gambia
Jacob Otu,1 Martin Antonio,1 Yin Bun Cheung,2 Simon Donkor,1 Bouke C. De Jong,1 Tumani Corrah,1 Richard A. Adegbola.1
Journal of Infection in Developing Countries , 2008,
Abstract: Background: The BACTEC MGIT 960 was evaluated and compared with BACTEC 9000 MB and Lowenstein-Jensen medium for recovery rate of mycobacteria, time to detection, and contamination rate.Methodology: 147 sputum samples obtained from patients with suspicion of tuberculosis were processed and inoculated into BACTEC MGIT 960, BACTEC 9000 MB and Lowenstein-Jensen medium using standardized procedures.Results: BACTEC MGIT 960 detected 57.1%; BACTEC 9000 MB detected 57.8%; and LJ medium detected 43.5% specimens with Mycobacterium tuberculosis complex (MTBC). BACTEC MGIT 960 had the shortest mean number of days (10.3) to detection, followed by BACTEC 9000 MB (13.2) and LJ medium (26.1). Sign rank test showed all three methods had significant difference in days to detection (each P<0.0001). About 39% of detection by BACTEC MGIT 960 took place within the first week, compared to 27.0% and 0.0% by BACTEC 9000 MB and LJ medium respectively. The best yield was obtained with BACTEC 9000 MB, but when compared with the BACTEC MGIT 960, it was not statistically significant. Performances were the same when the combination of a liquid plus a LJ medium were measured (P=0.05). Contamination rates were significantly higher in BACTEC MGIT 960 (12%) than in BACTEC 9000 MB (7%) (P=0.041) and LJ (4%) medium (P=0.022). BACTEC 9000 MB and LJ medium have lower contamination rates (P=0.607).Conclusions: BACTEC MGIT 960 had a shorter time to detection of MTBC than BACTEC 9000 MB and L J medium. Despite a higher contamination rate, its performance did not appear to be inferior.
Deciphering the Growth Behaviour of Mycobacterium africanum
Florian Gehre ,Jacob Otu,Kathryn DeRiemer,Paola Florez de Sessions,Martin L. Hibberd,Wim Mulders,Tumani Corrah,Bouke C. de Jong,Martin Antonio
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002220
Abstract: Background Human tuberculosis (TB) in West Africa is not only caused by M. tuberculosis but also by bacteria of the two lineages of M. africanum. For instance, in The Gambia, 40% of TB is due to infections with M. africanum West African 2. This bacterial lineage is associated with HIV infection, reduced ESAT-6 immunogenicity and slower progression to active disease. Although these characteristics suggest an attenuated phenotype of M. africanum, no underlying mechanism has been described. From the first descriptions of M. africanum in the literature in 1969, the time to a positive culture of M. africanum on solid medium was known to be longer than the time to a positive culture of M. tuberculosis. However, the delayed growth of M. africanum, which may correlate with the less virulent phenotype in the human host, has not previously been studied in detail. Methodology/Principal Findings We compared the growth rates of M. tuberculosis and M. africanum isolates from The Gambia in two liquid culture systems. M. africanum grows significantly slower than M. tuberculosis, not only when grown directly from sputa, but also in growth experiments under defined laboratory conditions. We also sequenced four M. africanum isolates and compared their whole genomes with the published M. tuberculosis H37Rv genome. M. africanum strains have several non-synonymous SNPs or frameshift mutations in genes that were previously associated with growth-attenuation. M. africanum strains also have a higher mutation frequency in genes crucial for transport of sulphur, ions and lipids/fatty acids across the cell membrane into the bacterial cell. Surprisingly, 5 of 7 operons, recently described as essential for intracellular survival of H37Rv in the host macrophage, showed at least one non-synonymously mutated gene in M. africanum. Conclusions/Significance The altered growth behaviour of M. africanum might indicate a different survival strategy within host cells.
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