Nasal Carriage of Staphylococcus aureus among Children in the Ashanti Region of Ghana

Background

Nasal carriage with Staphylococcus aureus is a common risk factor for invasive infections, indicating the necessity to monitor prevalent strains, particularly in the vulnerable paediatric population. This surveillance study aims to identify carriage rates, subtypes, antimicrobial susceptibilities and virulence markers of nasal S. aureus isolates collected from children living in the Ashanti region of Ghana.

Methods

Nasal swabs were obtained from children < 15 years of age on admission to the Agogo Presbyterian Hospital between April 2014 and January 2015. S. aureus isolates were characterized by their antimicrobial susceptibility, the presence of genes encoding for Panton-Valentine leukocidin (PVL) and toxic shock syndrome toxin-1 (TSST-1) and further differentiated by spa-typing and multi-locus-sequence-typing.

Results

Out of 544 children 120 (22.1%) were colonized with S. aureus, with highest carriage rates during the rainy seasons (27.2%; p = 0.007), in females aged 6–8 years (43.7%) and males aged 8–10 years (35.2%). The 123 isolates belonged to 35 different spa-types and 19 sequence types (ST) with the three most prevalent spa-types being t355 (n = 25), t84 (n = 18), t939 (n = 13), corresponding to ST152, ST15 and ST45. Two (2%) isolates were methicillin-resistant S. aureus (MRSA), classified as t1096 (ST152) and t4454 (ST45), and 16 (13%) were resistant to three or more different antimicrobial classes. PVL and TSST-1 were detected in 71 (58%) and 17 (14%) isolates respectively.

Conclusion

S. aureus carriage among Ghanaian children seems to depend on age, sex and seasonality. While MRSA rates are low, the high prevalence of PVL is of serious concern as these strains might serve not only as a source for severe invasive infections but may also transfer genes, leading to highly virulent MRSA clones.

Transcriptomic signatures differentiate survival from fatal outcomes in humans infected with Ebola virus

Background

In 2014, Western Africa experienced an unanticipated explosion of Ebola virus infections. What distinguishes fatal from non-fatal outcomes remains largely unknown, yet is key to optimising personalised treatment strategies. We used transcriptome data for peripheral blood taken from infected and convalescent recovering patients to identify early stage host factors that are associated with acute illness and those that differentiate patient survival from fatality.

Results

The data demonstrate that individuals who succumbed to the disease show stronger upregulation of interferon signalling and acute phase responses compared to survivors during the acute phase of infection. Particularly notable is the strong upregulation of albumin and fibrinogen genes, which suggest significant liver pathology. Cell subtype prediction using messenger RNA expression patterns indicated that NK-cell populations increase in patients who survive infection. By selecting genes whose expression properties discriminated between fatal cases and survivors, we identify a small panel of responding genes that act as strong predictors of patient outcome, independent of viral load.

Conclusions

Transcriptomic analysis of the host response to pathogen infection using blood samples taken during an outbreak situation can provide multiple levels of information on both disease state and mechanisms of pathogenesis. Host biomarkers were identified that provide high predictive value under conditions where other predictors, such as viral load, are poor prognostic indicators. The data suggested that rapid analysis of the host response to infection in an outbreak situation can provide valuable information to guide an understanding of disease outcome and mechanisms of disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-016-1137-3) contains supplementary material, which is available to authorized users.

Validation and Identification of Invasive Salmonella Serotypes in Sub-Saharan Africa by Multiplex Polymerase Chain Reaction

Salmonella enterica serovar Typhi and nontyphoidal Salmonella (NTS) cause the majority of bloodstream infections in sub-Saharan Africa; however, serotyping is rarely performed. We validated a multiplex polymerase chain reaction (PCR) assay with the White-Kauffmann-Le Minor (WKLM) scheme of serotyping using 110 Salmonella isolates from blood cultures of febrile children in Ghana and applied the method in other Typhoid Fever Surveillance in Africa Program study sites. In Ghana, 47 (43%) S. Typhi, 36 (33%) Salmonella enterica serovar Typhimurium, 14 (13%) Salmonella enterica serovar Dublin, and 13 (12%) Salmonella enterica serovar Enteritidis were identified by both multiplex PCR and the WKLM scheme separately. Using the validated multiplex PCR assay, we identified 42 (66%) S. Typhi, 14 (22%) S. Typhimurium, 2 (3%) S. Dublin, 2 (3%) S. Enteritidis, and 4 (6%) other Salmonella species from the febrile patients in Burkina Faso, Guinea-Bissau, Madagascar, Senegal, and Tanzania. Application of this multiplex PCR assay in sub-Saharan Africa could advance the knowledge of serotype distribution of Salmonella.

The Relationship Between Invasive Nontyphoidal Salmonella Disease, Other Bacterial Bloodstream Infections, and Malaria in Sub-Saharan Africa

BACKGROUND

Country-specific studies in Africa have indicated that Plasmodium falciparum is associated with invasive nontyphoidal Salmonella (iNTS) disease. We conducted a multicenter study in 13 sites in Burkina Faso, Ethiopia, Ghana, Guinea-Bissau, Kenya, Madagascar, Senegal, South Africa, Sudan, and Tanzania to investigate the relationship between the occurrence of iNTS disease, other systemic bacterial infections, and malaria.

METHODS

Febrile patients received a blood culture and a malaria test. Isolated bacteria underwent antimicrobial susceptibility testing, and the association between iNTS disease and malaria was assessed.

RESULTS

A positive correlation between frequency proportions of malaria and iNTS was observed (P = .01; r = 0.70). Areas with higher burden of malaria exhibited higher odds of iNTS disease compared to other bacterial infections (odds ratio [OR], 4.89; 95% CI, 1.61-14.90; P = .005) than areas with lower malaria burden. Malaria parasite positivity was associated with iNTS disease (OR, 2.44; P = .031) and gram-positive bacteremias, particularly Staphylococcus aureus, exhibited a high proportion of coinfection with Plasmodium malaria. Salmonella Typhimurium and Salmonella Enteritidis were the predominant NTS serovars (53/73; 73%). Both moderate (OR, 6.05; P = .0001) and severe (OR, 14.62; P < .0001) anemia were associated with iNTS disease.

CONCLUSIONS

A positive correlation between iNTS disease and malaria endemicity, and the association between Plasmodium parasite positivity and iNTS disease across sub-Saharan Africa, indicates the necessity to consider iNTS as a major cause of febrile illness in malaria-holoendemic areas. Prevention of iNTS disease through iNTS vaccines for areas of high malaria endemicity, targeting high-risk groups for Plasmodium parasitic infection, should be considered.

Antibiotic resistance and clonal diversity of invasive Staphylococcus aureus in the rural Ashanti Region, Ghana

Background

Staphylococcus aureus is among the most common pathogens isolated from blood cultures in Ghana; yet the epidemiology of blood infections in rural settings is poorly described. This study aims to investigate antimicrobial susceptibility and clonal diversity of S. aureus causing bloodstream infections in two hospitals in the Ashanti Region, Ghana.

Methods

Blood cultures were performed for all febrile patients (≥37.5 °C) on hospital admission. Antibiotic susceptibility testing for S. aureus isolates was carried out by the VITEK 2 system. Multiplex polymerase chain reaction (PCR) was used to detect S. aureus-specific nuc gene, Panton-Valentine leukocidin (PVL), and methicillin-resistant S. aureus (MRSA)-specific mecA and mecC genes. The population structure of S. aureus was assessed by spa typing.

Results

In total, 9,834 blood samples were cultured, out of which 0.6% (n = 56) were positive for S. aureus. Multidrug resistance (MDR) was detected in 35.7% (n = 20) of the S. aureus strains, of which one was a MRSA. The highest rate of antibiotic resistance was seen for commonly available antibiotics, including penicillin (n = 55; 98.2%), tetracycline (n = 32; 57.1%) and trimethoprim/sulfamethoxazole (n = 26; 46.4%). Of all S. aureus strains, 75.0% (n = 42) carried the PVL-encoding genes. We found 25 different spa types with t355 (n = 11; 19.6%), t314 (n = 8; 14.3%), t084 (n = 8; 14.3%) and t311 (n = 5; 8.9%) being predominant.

Conclusion

The study exhibited an alarmingly large level of antibiotic resistance to locally available antibiotics. The frequency of genetically diverse and PVL-positive methicillin-sensitive S. aureus (MSSA) was high and could represent a reservoir for the emergence of virulent PVL-positive MRSA clones.

Analysis of Diagnostic Findings From the European Mobile Laboratory in Guéckédou, Guinea, March 2014 Through March 2015

Background. A unit of the European Mobile Laboratory (EMLab) consortium was deployed to the Ebola virus disease (EVD) treatment unit in Guéckédou, Guinea, from March 2014 through March 2015.

Methods. The unit diagnosed EVD and malaria, using the RealStar Filovirus Screen reverse transcription–polymerase chain reaction (RT-PCR) kit and a malaria rapid diagnostic test, respectively.

Results. The cleaned EMLab database comprised 4719 samples from 2741 cases of suspected EVD from Guinea. EVD was diagnosed in 1231 of 2178 hospitalized patients (57%) and in 281 of 563 who died in the community (50%). Children aged <15 years had the highest proportion of Ebola virus–malaria parasite coinfections. The case-fatality ratio was high in patients aged <5 years (80%) and those aged >74 years (90%) and low in patients aged 10–19 years (40%). On admission, RT-PCR analysis of blood specimens from patients who died in the hospital yielded a lower median cycle threshold (Ct) than analysis of blood specimens from survivors (18.1 vs 23.2). Individuals who died in the community had a median Ct of 21.5 for throat swabs. Multivariate logistic regression on 1047 data sets revealed that low Ct values, ages of <5 and ≥45 years, and, among children aged 5–14 years, malaria parasite coinfection were independent determinants of a poor EVD outcome.

Conclusions. Virus load, age, and malaria parasite coinfection play a role in the outcome of EVD.

Extended spectrum beta-lactamase producing Enterobacteriaceae causing bloodstream infections in rural Ghana, 2007-2012

BACKGROUND

High prevalence of Extended Spectrum Beta-Lactamase (ESBL) producing Enterobacteriaceae threatens treatment options for invasive bloodstream infections in sub-Saharan Africa.

OBJECTIVES

To explore the frequency and genotype distribution of ESBL producing Enterobacteriaceae causing bloodstream infections in a primary health care setting in rural Ghana.

METHODS

Blood cultures from all patients with fever ≥38°C within 24h after admission (community-acquired) and from all neonates with suspected neonatal sepsis (hospital-acquired) were obtained. ESBL-producing isolates were characterized by combined disc test and by amplifying the blaCTX-M, blaTEM and blaSHV genes. Multilocus sequence typing (MLST) was performed for all ESBL-producing Klebsiella pneumoniae and Escherichia coli isolates, and all K. pneumoniae isolates were differentiated by pulsed-field gel electrophoresis (PFGE).

RESULTS

Among 426 Enterobacteriaceae isolated from blood cultures, non-typhoid Salmonella (n=215, 50.8%), S. Typhi (n=110, 26.0%), E. coli (n=50, 11.8%) and K. pneumoniae (n=41, 9.7%) were the most frequent. ESBL-producing isolates were restricted to the CTX-M-15 genotype and the species K. pneumoniae (n=34, 82.9%), Enterobacter cloacae complex (n=2, 66.7%) and E. coli (n=5, 10.0%). The rates of ESBL-producers in K. pneumoniae were 55.6% and 90.6% in community-acquired and neonatal bloodstream infections, respectively. MLST and PFGE analysis identified four outbreak clusters among neonates.

CONCLUSIONS

Considering the rural primary health care study setting, the high proportion of ESBL-producing Klebsiella pneumoniae is worrisome and might be devastating in the absence of second line antibiotics. Therefore, enhanced diagnostic laboratories for surveillance purposes and sustainable hospital hygiene measures must be considered to prevent further spread of multidrug resistant bacteria within rural communities.

Culex pipiens and Culex torrentium populations from Central Europe are susceptible to West Nile virus infection

West Nile virus (WNV), a Flavivirus with an avian primary host, is already widespread in Europe and might also pose an infection risk to Germany, should competent mosquito vectors be present. Therefore, we analysed the ability of WNV to infect German Culex mosquitoes with special emphasis on field collected specimens of Culex torrentium and Culex pipiens biotype pipiens. We collected egg rafts of Culex mosquitoes over two subsequent seasons at two geographically distinct sampling areas in Germany and differentiated the samples by molecular methods. Adult females, reared from the various egg rafts, were challenged with WNV by feeding of artificial blood meals. WNV infection was confirmed by real-time RT-PCR and virus titration. The results showed that field collected C. pipiens biotype pipiens and C. torrentium mosquitoes native to Germany are susceptible to WNV infection at 25 °C as well as 18 °C incubation temperature. C. torrentium mosquitoes, which have not been established as WNV vector so far, were the most permissive species tested with maximum infection rates of 96% at 25 °C. Furthermore, a disseminating infection was found in up to 94% of tested C. pipiens biotype pipiens and 100% of C. torrentium. Considering geographical variation of susceptibility, C. pipiens biotype pipiens mosquitoes from Southern Germany were more susceptible to WNV infection than corresponding populations from Northern Germany. All in all, we observed high infection and dissemination rates even at a low average ambient temperature of 18 °C. The high susceptibility of German Culex populations for WNV indicates that an enzootic transmission cycle in Germany could be possible.

Application of a multiplex PCR assay for the detection of gastrointestinal pathogens in a rural African setting

BACKGROUND

Despite high morbidity and mortality, the laboratory diagnosis of gastrointestinal infections is largely neglected in tropical African settings. This study aims to apply the Luminex multiplex PCR assay for the diagnosis of gastrointestinal pathogens in rural Ghana to evaluate its usefulness as a routine method.

METHODS

A case-control study was conducted at the Agogo Presbyterian Hospital in Ghana. Stool samples were collected from children below 6 years of age with (cases) and without (controls) diarrhoea. Samples were screened for 15 different diarrhoeal pathogens by the Luminex xTAG GPP assay and associations between diarrhoea and gastrointestinal infections and fractions attributable to diarrhea (AF) were determined.

RESULTS

The Luminex PCR assay identified organisms in 96.6% (n = 428) of 443 cases and in 92.5% (n = 221) of 239 selected controls. A mean of 2.5 (standard deviation [SD]: ± 1.3) and 2.3 (SD: ± 1.3) organisms per sample were detected in cases and controls respectively. An association with diarrhoea was found for rotavirus (adjusted odds ratio [aOR] = 7.2; 95% confidence interval [CI]: 2.9-18.1), norovirus (aOR = 2.7; 95% CI: 1.4-5.3) and Shigella spp. (aOR = 1.7; 95% CI: 1.2-2.4) with respective AFs of 12.5% (95% CI: 9.6-15.3), 7.9% (95% CI: 3.8-11.7) and 16.9% (95% CI: 6.9-25.9).

CONCLUSION

The high proportion of pathogen-positive stool samples with a high number of co-infections in cases and controls suggests a substantial amount of transient or colonizing microorganisms for which treatment is not necessarily implicated. The use of sequential diagnostic algorithms with pathogen specific or quantitative PCRs might be most appropriate for diagnosing gastrointestinal infections.

A Multicountry Molecular Analysis of Salmonella enterica Serovar Typhi With Reduced Susceptibility to Ciprofloxacin in Sub-Saharan Africa

BACKGROUND

Salmonella enterica serovar Typhi is a predominant cause of bloodstream infections in sub-Saharan Africa (SSA). Increasing numbers of S. Typhi with resistance to ciprofloxacin have been reported from different parts of the world. However, data from SSA are limited. In this study, we aimed to measure the ciprofloxacin susceptibility of S. Typhi isolated from patients with febrile illness in SSA.

METHODS

Febrile patients from 9 sites within 6 countries in SSA with a body temperature of ≥38.0°C were enrolled in this study. Blood samples were obtained for bacterial culture, and Salmonella isolates were identified biochemically and confirmed by multiplex polymerase chain reaction (PCR). Antimicrobial susceptibility of all Salmonella isolates was performed by disk diffusion test, and minimum inhibitory concentrations (MICs) against ciprofloxacin were measured by Etest. All Salmonella isolates with reduced susceptibility to ciprofloxacin (MIC > 0.06 µg/mL) were screened for mutations in quinolone resistance-determining regions in target genes, and the presence of plasmid-mediated quinolone resistance (PMQR) genes was assessed by PCR.

RESULTS

A total of 8161 blood cultures were performed, and 100 (1.2%) S. Typhi, 2 (<0.1%) Salmonella enterica serovar Paratyphi A, and 27 (0.3%) nontyphoid Salmonella (NTS) were isolated. Multidrug-resistant S. Typhi were isolated in Kenya (79% [n = 38]) and Tanzania (89% [n = 8]) only. Reduced ciprofloxacin-susceptible (22% [n = 11]) S. Typhi were isolated only in Kenya. Among those 11 isolates, all had a Glu133Gly mutation in the gyrA gene combined with either a gyrA (Ser83Phe) or gyrB mutation (Ser464Phe). One Salmonella Paratyphi A isolate with reduced susceptibility to ciprofloxacin was found in Senegal, with 1 mutation in gyrA (Ser83Phe) and a second mutation in parC (Ser57Phe). Mutations in the parE gene and PMQR genes were not detected in any isolate.

CONCLUSIONS

Salmonella Typhi with reduced susceptibility to ciprofloxacin was not distributed homogenously throughout SSA. Its prevalence was very high in Kenya, and was not observed in other study countries. Continuous monitoring of antimicrobial susceptibility is required to follow the potential spread of antimicrobial-resistant isolates throughout SSA.

Spatial heterogeneity of malaria in Ghana: a cross-sectional study on the association between urbanicity and the acquisition of immunity

Background

Malaria incidence has declined considerably over the last decade. This is partly due to a scale-up of control measures but is also attributed to increasing urbanization. This study aimed to analyse the association between malaria and urbanization and the effect of urbanicity on the acquisition of semi-immunity.

Methods

In 2012, children with fever presenting to St Michael’s Hospital Pramso/Ghana were recruited. The malaria-positive-fraction (MPF) of fever cases was calculated on community-level to approximate the malaria risk. The mean age of malaria cases was calculated for each community to estimate the acquisition of semi-immunity. The level of urbanicity for the communities was calculated and associations between MPF, urbanicity and immunity were modelled using linear regression.

Results

Twenty-six villages were included into the study with a mean MPF of 35 %. A linear decrease of 5 % (95 % CI: 4–6 %) in MPF with every ten-point increase in urbanicity was identified. The mean age of malaria patients increased by 2.9 months (95 % CI: 1.0–4.8) with every ten-point increase in urbanicity.

Discussion

The results confirm an association between an increase in urbanicity and declining malaria risk and demonstrate that the acquisition of semi-immunity is heterogeneous on a micro-epidemiological scale and is associated with urbanicity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-016-1138-4) contains supplementary material, which is available to authorized users.

Tropheryma whipplei in children with diarrhoea in rural Ghana

Tropheryma whipplei has been hypothesized to be able to cause diarrhoea, but data from young children are scarce. In this hospital-based case-control study 534 stool samples of children aged between 2 months and 15 years from rural Ghana were analysed for the presence of T. whipplei. Overall stool prevalence of T. whipplei was high (27.5%). Although there was no difference in T. whipplei carriage overall between cases and controls, cases aged between 0 and 12 months carried T. whipplei in their stool twice as often as controls without diarrhoea. The results from this study may support the hypothesis that T. whipplei can cause diarrhoea in first-time infection.

Urbanicity and Paediatric Bacteraemia in Ghana-A Case-Control Study within a Rural-Urban Transition Zone

BACKGROUND

Systemic bacterial infections are a major cause of paediatric febrile illness in sub-Saharan Africa. Aim of this study was to assess the effects of social and geographical determinants on the risk of bacteraemia in a rural-urban transition zone in Ghana.

METHODS

Children below 15 years of age with fever were recruited at an outpatient department in the suburban belt of Kumasi, Ghana's second largest city. Blood was taken for bacterial culture and malaria diagnostics. The socio-economic status of participants was calculated using Principle Component Analysis. A scale, based on key urban characteristics, was established to quantify urbanicity for all communities in the hospital catchment area. A case-control analysis was conducted, where children with and without bacteraemia were cases and controls, respectively.

RESULTS

Bacteraemia was detected in 72 (3.1%) of 2,306 hospital visits. Non-typhoidal Salmonella (NTS; n = 24; 33.3%) and Salmonella typhi (n = 18; 25.0%) were the most common isolates. Logistic regression analysis showed that bacteraemia was negatively associated with urbanicity (odds ratio [OR] = 0.8; 95% confidence interval [CI]: 0.7-1.0) and socio-economic status (OR = 0.8; 95% CI: 0.6-0.9). Both associations were stronger if only NTS infections were used as cases (OR = 0.5; 95% CI: 0.3-0.8 and OR = 0.6; 95% CI: 0.4-1.0, respectively).

CONCLUSIONS

The results of this study highlight the importance of individual as well as community factors as independent risk factors for invasive bacterial infection (IBI) and especially NTS. Epidemiological data support physicians, public health experts and policy makers to identify disease prevention and treatment needs in order to secure public health in the transitional societies of developing countries.

Drinking water from dug wells in rural ghana--salmonella contamination, environmental factors, and genotypes

Salmonellosis is an important but neglected disease in sub-Saharan Africa. Food or fecal-oral associated transmissions are the primary cause of infections, while the role of waterborne transmission is unclear. Samples were collected from different dug wells in a rural area of Ghana and analyzed for contamination with bacteria, and with Salmonella in particular. In addition, temporal dynamics and riks factors for contamination were investigated in 16 wells. For all Salmonella isolates antibiotic susceptibility testing was performed, serovars were determined and strains from the same well with the same serovar were genotyped. The frequency of well water contamination with Gram-negative rod-shaped bacteria was 99.2% (n = 395). Out of 398 samples, 26 (6.5%) tested positive for Salmonella spp. The serovar distribution was diverse including strains not commonly isolated from clinical samples. Resistance to locally applied antibiotics or resistance to fluoroquinolones was not seen in the Salmonella isolates. The risk of Salmonella contamination was lower in wells surrounded by a frame and higher during the rainy season. The study confirms the overall poor microbiological quality of well water in a resource-poor area of Ghana. Well contamination with Salmonella poses a potential threat of infection, thus highlighting the important role of drinking water safety in infectious disease control.

Molecular characterization of Cryptosporidium spp. among children in rural Ghana

Background

The relevance of Cryptosporidium infections for the burden of childhood diarrhoea in endemic settings has been shown in recent years. This study describes Cryptosporidium subtypes among symptomatic and asymptomatic children in rural Ghana to analyse subtype-specific demographic, geographical, seasonal and clinical differences in order to inform appropriate control measures in endemic areas.

Methodology/Principal Findings

Stool samples were collected from 2232 children below 14 years of age presenting with and without gastrointestinal symptoms at the Agogo Presbyterian Hospital in the rural Ashanti region of Ghana between May 2007 and September 2008. Samples were screened for Cryptosporidium spp. by PCR and isolates were classified into subtypes based on sequence differences in the gp60 gene. Subtype specific frequencies for age, sex, location and season have been determined and associations with disease symptoms have been analysed within a case-control study.

Cryptosporidium infections were diagnosed in 116 of 2232 (5.2%) stool samples. Subtyping of 88 isolates revealed IIcA5G3 (n = 26, 29.6%), IbA13G3 (n = 17, 19.3%) and IaA21R3 (n = 12, 13.6%) as the three most frequent subtypes of the two species C. hominis and C. parvum, known to be transmitted anthroponotically. Infections peak at early rainy season with 67.9% and 50.0% of infections during the months April, May and June for 2007 and 2008 respectively. C. hominis infection was mainly associated with diarrhoea (odds ratio [OR] = 2.4; 95% confidence interval [CI]: 1.2–4.9) whereas C. parvum infection was associated with both diarrhoea (OR = 2.6; CI: 1.2–5.8) and vomiting (OR = 3.1; 95% CI: 1.5–6.1).

Conclusions/Significance

Cryptosporidiosis is characterized by seasonal anthroponotic transmission of strains typically found in Sub-Saharan Africa. The infection mainly affects young infants, with vomiting and diarrhoea being one of the leading symptoms in C. parvum infection. Combining molecular typing and clinical data provides valuable information for physicians and is able to track sources of infections.

Cryptosporidium spp. are a frequent cause of diarrhoea worldwide. While both animal-to-human and human-to-human transmission has been reported from industrialized countries, human-to-human transmission clearly prevails in Sub-Saharan Africa. However, data on the distribution of zoonotic and human subtypes is limited for rural African regions, where children are in very close contact to animals. We conducted a case-control study with 2232 stool samples from symptomatic and asymptomatic children living in the rural Ashanti region of Ghana. The combination of molecular typing results and clinical data helped to untangle transmission routes and to analyze the association of clinical symptoms with specific Cryptosporidium subtypes. Our study results demonstrate seasonal transmission with no clusters of specific subtypes. All subtypes detected have so far been only encountered from human specimens, strongly suggesting a predominantly human-human transmission among children living in the rural Ghana, despite close contact to livestock. Therefore, public health control programmes need to primarily focus on hygienic conditions among young infants below the age of two years. Of interest for practicing physicians, vomiting is a frequent symptom, especially in C. parvum infections.

Gastrointestinal infections and diarrheal disease in Ghanaian infants and children: an outpatient case-control study

Introduction

Diarrheal diseases are among the most frequent causes of morbidity and mortality in children worldwide, especially in resource-poor areas. This case-control study assessed the associations between gastrointestinal infections and diarrhea in children from rural Ghana.

Methods

Stool samples were collected from 548 children with diarrhea and from 686 without gastrointestinal symptoms visiting a hospital from 2007–2008. Samples were analyzed by microscopy and molecular methods.

Results

The organisms most frequently detected in symptomatic cases were Giardia lamblia, Shigella spp./ enteroinvasive Escherichia coli (EIEC), and Campylobacter jejuni. Infections with rotavirus (adjusted odds ratio [aOR] = 8.4; 95% confidence interval [CI]: 4.3–16.6), C. parvum/hominis (aOR = 2.7; 95% CI: 1.4–5.2) and norovirus (aOR = 2.0; 95%CI: 1.3–3.0) showed the strongest association with diarrhea. The highest attributable fractions (AF) for diarrhea were estimated for rotavirus (AF = 14.3%; 95% CI: 10.9–17.5%), Shigella spp./EIEC (AF = 10.5%; 95% CI: 3.5–17.1%), and norovirus (AF = 8.2%; 95% CI 3.2–12.9%). Co-infections occurred frequently and most infections presented themselves independently of other infections. However, infections with E. dispar, C. jejuni, and norovirus were observed more often in the presence of G. lamblia.

Conclusions

Diarrheal diseases in children from a rural area in sub-Saharan Africa are mainly due to infections with rotavirus, Shigella spp./EIEC, and norovirus. These associations are strongly age-dependent, which should be considered when diagnosing causes of diarrhea. The presented results are informative for both clinicians treating gastrointestinal infections as well as public health experts designing control programs against diarrheal diseases.

Gastrointestinal infections are frequent in many low-income countries. However, their role in diarrheal diseases is still under discussion. Many epidemiological studies focus on individuals with diarrheal symptoms only, ignoring the fact that infections may progress asymptomatically as well. In order to identify infectious agents associated with diarrhea it is imperative to consider cases without symptoms as a control group. We conducted a case-control study, including 548 children with diarrhea and 651 children without gastrointestinal symptoms in order to untangle the role of gastrointestinal infections in diarrheal disease. As shown in other studies infections with rotavirus, Shigella spp./EIEC and norovirus are responsible for the main diarrhea burden. Co-infections are frequently observed in our study group and some organisms occur more frequently in the presence of a second one. Especially Giardia lamblia, which is not associated with diarrhea, is more often observed along with Campylobacter jejuni and norovirus, which are responsible for a high number of diarrheal episodes. This may be of particular interest since G. lamblia is, with a frequency of 40% within the study group, the most prevalent organism observed. Furthermore, the high number of co-infections challenged the identification of causative pathogens since diagnosing a particular isolate may not rule out the effect of another potentially infectious agent in diarrheal disease. We observed a strong effect of age on the course of an infection, which may guide clinicians when diagnosing causes of diarrhea.

Mobile phone-based mHealth approaches for public health surveillance in sub-Saharan Africa: a systematic review

Whereas mobile phone-based surveillance has the potential to provide real-time validated data for disease clustering and prompt respond and investigation, little evidence is available on current practice in sub-Sahara Africa. The objective of this review was to examine mobile phone-based mHealth interventions for Public Health surveillance in the region. We conducted electronic search in MEDLINE, EMBASE, IEE Xplore, African Index Medicus (AIM), BioMed Central, PubMed Central (PMC), the Public Library of Science (PLoS) and IRIS for publications used in the review. In all, a total of nine studies were included which focused on infectious disease surveillance of malaria (n = 3), tuberculosis (n = 1) and influenza-like illnesses (n = 1) as well as on non-infectious disease surveillance of child malnutrition (n = 2), maternal health (n = 1) and routine surveillance of various diseases and symptoms (n = 1). Our review revealed that mobile phone-based surveillance projects in the sub-Saharan African countries are on small scale, fragmented and not well documented. We conclude by advocating for a strong drive for more research in the applied field as well as a better reporting of lessons learned in order to create an epistemic community to help build a more evidence-based field of practice in mHealth surveillance in the region.

Health care utilization and symptom severity in Ghanaian children--a cross-sectional study

The aim of this study was to identify factors influencing health care utilization behavior for children with mild or severe disease symptoms in rural Ghana. Between March and September 2008 a cross-sectional health care utilization survey was conducted and 8,715 caregivers were interviewed regarding their intended behavior in case their children had mild or severe fever or diarrhea. To show associations between hospital attendance and further independent factors (e.g. travel distance or socio-economic status) prevalence ratios were calculated for the four disease symptoms. A Poisson regression model was used to control for potential confounding. Frequency of hospital attendance decreased constantly with increasing distance to the health facility. Being enrolled in the national health insurance scheme increased the intention to attend a hospital. The effect of the other factors diminished in the Poisson regression if modeled together with travel distance. The observed associations weakened with increasing severity of symptoms, which indicates that barriers to visit a hospital are less important if children experience a more serious illness. As shown in other studies, travel distance to a health care provider had the strongest effect on health care utilization. Studies to identify local barriers to access health care services are important to inform health policy making as they identify deprived populations with low access to health services and to early treatment.

Development of a resource modelling tool to support decision makers in pandemic influenza preparedness: The AsiaFluCap Simulator

BACKGROUND

Health care planning for pandemic influenza is a challenging task which requires predictive models by which the impact of different response strategies can be evaluated. However, current preparedness plans and simulations exercises, as well as freely available simulation models previously made for policy makers, do not explicitly address the availability of health care resources or determine the impact of shortages on public health. Nevertheless, the feasibility of health systems to implement response measures or interventions described in plans and trained in exercises depends on the available resource capacity. As part of the AsiaFluCap project, we developed a comprehensive and flexible resource modelling tool to support public health officials in understanding and preparing for surges in resource demand during future pandemics.

RESULTS

The AsiaFluCap Simulator is a combination of a resource model containing 28 health care resources and an epidemiological model. The tool was built in MS Excel© and contains a user-friendly interface which allows users to select mild or severe pandemic scenarios, change resource parameters and run simulations for one or multiple regions. Besides epidemiological estimations, the simulator provides indications on resource gaps or surpluses, and the impact of shortages on public health for each selected region. It allows for a comparative analysis of the effects of resource availability and consequences of different strategies of resource use, which can provide guidance on resource prioritising and/or mobilisation. Simulation results are displayed in various tables and graphs, and can also be easily exported to GIS software to create maps for geographical analysis of the distribution of resources.

CONCLUSIONS

The AsiaFluCap Simulator is freely available software (http://www.cdprg.org) which can be used by policy makers, policy advisors, donors and other stakeholders involved in preparedness for providing evidence based and illustrative information on health care resource capacities during future pandemics. The tool can inform both preparedness plans and simulation exercises and can help increase the general understanding of dynamics in resource capacities during a pandemic. The combination of a mathematical model with multiple resources and the linkage to GIS for creating maps makes the tool unique compared to other available software.

Incidence and characteristics of bacteremia among children in rural Ghana

The objective of the study was to describe systemic bacterial infections occurring in acutely ill and hospitalized children in a rural region in Ghana, regarding frequency, incidence, antimicrobial susceptibility patterns and associations with anthropometrical data.

Blood cultures were performed in all children below the age of five years, who were admitted to Agogo Presbyterian Hospital (APH), Asante Region, Ghana, between September 2007 and July 2009. Medical history and anthropometrical data were assessed using a standardized questionnaire at admission. Incidences were calculated after considering the coverage population adjusted for village-dependent health-seeking behavior.

Among 1,196 hospitalized children, 19.9% (n = 238) were blood culture positive. The four most frequent isolated pathogens were nontyphoidal salmonellae (NTS) (53.3%; n = 129), Staphylococcus aureus (13.2%; n = 32), Streptococcus pneumoniae (9.1%; n = 22) and Salmonella ser. Typhi (7.0%; n = 17). Yearly cumulative incidence of bacteremia was 46.6 cases/1,000 (CI 40.9–52.2). Yearly cumulative incidences per 1,000 of the four most frequent isolates were 25.2 (CI 21.1–29.4) for NTS, 6.3 (CI 4.1–8.4) for S. aureus, 4.3 (CI 2.5–6.1) for S. pneumoniae and 3.3 (CI 1.8–4.9) for Salmonella ser. Typhi. Wasting was positively associated with bacteremia and systemic NTS bloodstream infection. Children older than three months had more often NTS bacteremia than younger children. Ninety-eight percent of NTS and 100% of Salmonella ser. Typhi isolates were susceptible to ciprofloxacin, whereas both tested 100% susceptible to ceftriaxone. Seventy-seven percent of NTS and 65% of Salmonella ser. Typhi isolates were multi-drug resistant (MDR). Systemic bacterial infections in nearly 20% of hospitalized children underline the need for microbiological diagnostics, to guide targeted antimicrobial treatment and prevention of bacteremia. If microbiological diagnostics are lacking, calculated antimicrobial treatment of severely ill children in malaria-endemic areas should be considered.

Extrapolating respiratory tract infection incidences to a rural area of Ghana using a probability model for hospital attendance

OBJECTIVE

The aim of the current study was to extrapolate incidences for respiratory tract infections (RTI) using referral data from a local hospital in Ghana weighted by the individual likelihood of a hospital visit.

METHODS

Diagnoses from children visiting a rural hospital in Ghana during August 2007 to September 2008 were recorded. A logistic regression model, based on a population study conducted within the hospital catchment area, was used to calculate the individual probability of clinic attendance and to extrapolate the number of recorded cases. Cumulative incidences for children living in the hospital catchment area were estimated.

RESULTS

Upper RTI was the most common respiratory diagnosis, with an extrapolated incidence of 17481 cases per 100000 per year, followed by pneumonia with an incidence of 2496 per 100 000 per year. All diseases analyzed were most common in the first year of life.

CONCLUSIONS

In general the study results are in line with comparable studies. Several methodological issues biasing the results in different directions were identified. For example, opportunistic infections that are more often observed in hospital attendees are likely to be overestimated. However, the applied approach presents a tool for areas where disease monitoring systems are not established.

Pandemic influenza and health system resource gaps in Bali: an analysis through a resource transmission dynamics model

The failure to contain pandemic influenza A(H1N1) 2009 in Mexico has shifted global attention from containment to mitigation. Limited surveillance and reporting have, however, prevented detailed assessment of mitigation during the pandemic, particularly in low- and middle-income countries. To assess pandemic influenza case management capabilities in a resource-limited setting, the authors used a health system questionnaire and density-dependent, deterministic transmission model for Bali, Indonesia, determining resource gaps. The majority of health resources were focused in and around the provincial capital, Denpasar; however, gaps are found in every district for nursing staff, surgical masks, and N95 masks. A relatively low pathogenicity pandemic influenza virus would see an overall surplus for physicians, antivirals, and antimicrobials; however, a more pathogenic virus would lead to gaps in every resource except antimicrobials. Resources could be allocated more evenly across Bali. These, however, are in short supply universally and therefore redistribution would not fill resource gaps.

Developing policy options for SARS and SARS-like diseases - a Delphi study

The objective of the SARSControl Delphi study was to develop options for national and international emerging infectious diseases policies. The aim of this paper is to present the results of the study, which gathered expert opinions on gaps and inconsistencies concerning preparedness and response planning for Severe Acute Respiratory Syndrome (SARS) and SARS-like diseases. The Delphi technique was employed, which comprised a pilot round, two written rounds and a face-to-face meeting. The Delphi panel consisted of 38 experts from 22 countries, who highlighted the necessity to test plans and stressed the importance of surveillance measures for the swift containment of communicable disease outbreaks and the inclusion of detailed triage plans in national pandemic plans. The experts also suggested a need to define criteria for testing pandemic preparedness plans at different regional levels. New policy alternatives were identified, such as the need for generic plans on pandemics and universal access to healthcare during an outbreak. The usefulness of some non-medical interventions, such as bans on travel, could not be established and need further research. Dissemination of the findings will help to bridge gaps and rectify inconsistencies in current pandemic planning and response strategies for SARS and SARS-like diseases, as well as add valuable knowledge towards the development of national and international emerging infectious disease policies.

Evaluating health systems' preparedness for emerging infectious diseases: a novel conceptual and analytic framework

In this article we present a novel conceptual framework for systematically assessing the national health system capacity to respond to pandemic influenza. This framework helps to determine how health systems and pandemic programmes interact, whether, where and which weak points exist, and how and where pandemic response health programmes can be improved effectively. This new conceptual framework draws upon two existing approaches for assessment and evaluation, the Systemic Rapid Assessment Toolkit (SYSRA) and the Hazard Analysis of Critical Control Points (HACCP). SYSRA is a systematic approach to analyse the interplay between communicable disease programmes and the broader health systems context within which they operate and the HACCP methodology builds upon a systematic analysis of process steps within a programme in order to identify likely hazards and to develop control measures to address them. The analytical framework that we have developed from the novel conceptualisation is simple, can be applied rapidly, and should, we believe, be low cost to implement. Thus, this provides a means for developing a contextual understanding of the broader health system in which a pandemic infectious disease programme operates, and for identifying frailties in programmes that need to be responded to.

Pandemic influenza preparedness and health systems challenges in Asia: results from rapid analyses in 6 Asian countries

BACKGROUND

Since 2003, Asia-Pacific, particularly Southeast Asia, has received substantial attention because of the anticipation that it could be the epicentre of the next pandemic. There has been active investment but earlier review of pandemic preparedness plans in the region reveals that the translation of these strategic plans into operational plans is still lacking in some countries particularly those with low resources. The objective of this study is to understand the pandemic preparedness programmes, the health systems context, and challenges and constraints specific to the six Asian countries namely Cambodia, Indonesia, Lao PDR, Taiwan, Thailand, and Viet Nam in the prepandemic phase before the start of H1N1/2009.

METHODS

The study relied on the Systemic Rapid Assessment (SYSRA) toolkit, which evaluates priority disease programmes by taking into account the programmes, the general health system, and the wider socio-cultural and political context. The components under review were: external context; stewardship and organisational arrangements; financing, resource generation and allocation; healthcare provision; and information systems. Qualitative and quantitative data were collected in the second half of 2008 based on a review of published data and interviews with key informants, exploring past and current patterns of health programme and pandemic response.

RESULTS

The study shows that health systems in the six countries varied in regard to the epidemiological context, health care financing, and health service provision patterns. For pandemic preparation, all six countries have developed national governance on pandemic preparedness as well as national pandemic influenza preparedness plans and Avian and Human Influenza (AHI) response plans. However, the governance arrangements and the nature of the plans differed. In the five developing countries, the focus was on surveillance and rapid containment of poultry related transmission while preparation for later pandemic stages was limited. The interfaces and linkages between health system contexts and pandemic preparedness programmes in these countries were explored.

CONCLUSION

Health system context influences how the six countries have been preparing themselves for a pandemic. At the same time, investment in pandemic preparation in the six Asian countries has contributed to improvement in health system surveillance, laboratory capacity, monitoring and evaluation and public communications. A number of suggestions for improvement were presented to strengthen the pandemic preparation and mitigation as well as to overcome some of the underlying health system constraints.

Influenza--insights from mathematical modelling

BACKGROUND

When the first cases of a new infectious disease appear, questions arise about the further course of the epidemic and about the appropriate interventions to be taken to protect individuals and the public as a whole. Mathematical models can help answer these questions. In this article, the authors describe basic concepts in the mathematical modelling of infectious diseases, illustrate their use with a simple example, and present the results of influenza models.

METHOD

Description of the mathematical modelling of infectious diseases and selective review of the literature.

RESULTS

The two fundamental concepts of mathematical modelling of infectious diseases-the basic reproduction number and the generation time-allow a better understanding of the course of an epidemic. Modelling studies based on past influenza epidemics suggest that the rise of the epidemic curve can be slowed at the beginning of the epidemic by isolating ill persons and giving prophylactic medications to their contacts. Later on in the course of the epidemic, restricting the number of contacts (e.g., by closing schools) may mitigate the epidemic but will only have a limited effect on the total number of persons who contract the disease.

CONCLUSION

Mathematical modelling is a valuable tool for understanding the dynamics of an epidemic and for planning and evaluating interventions.

Controlling SARS: a review on China's response compared with other SARS-affected countries

OBJECTIVE

To summarise the major control measures implemented by severe acute respiratory syndrome (SARS)-affected countries and to compare distinctive features of the Chinese approach to other affected Asian countries and Canada.

METHOD

Literature review.

RESULTS

The realisation in March 2003 that SARS was spreading led affected countries to introduce measures such as rapid dissemination of information, early case detection and isolation, tracing and quarantining of SARS contacts, traveller screening, raising public awareness of risk and institution of stricter infection control in health care settings. SARS became a notifiable disease in China in mid-April 2003, after which introduction of efficient nationwide control measures led to containment within 2 months. Countries differed in the timeliness of implementing control measures, the mode and extent to which these were enforced and in the resources available to do so.

CONCLUSION

SARS challenged the political and public health systems of all affected countries. It demanded rapid and decisive action to be taken, yet the comparison shows how difficult this was for an unknown new disease. Guangdong reacted rapidly but this pace was not continued by China for some time, which facilitated national and international spread. Once the Chinese government changed its policy, it developed an impressive control strategy involving the public which culminated in containment. The significance of timely information was perhaps the main lesson which the SARS epidemic taught.

[Prevention and control of infectious diseases with pandemic potential: the EU-project SARSControl]

INTRODUCTION

The influenza pandemics of the 20th century, the SARS epidemic in 2002/03 and the growing number of human cases infected with the H5N1 avian influenza virus clearly demonstrate that the threat of new pandemics is very real. These events have intensified pandemic prevention and control activities worldwide. "SARSControl" is a three-year project funded by the European Commission with the objective to aid European member states in the public health management of new emerging infections. This article summarises the main research results and recommendations arising from this project.

METHOD

The reports and papers published in the SARSControl project form the basis of this article. In addition, a literature search for SARS and pandemic influenza was conducted and information on pandemic planning and management guidelines obtained from the WHO and EU websites. The project results are discussed in this context.

RESULTS

A lack of knowledge and delayed international communication resulted in the rapid spread of SARS, highlighting the importance of a global system for rapid and transparent information transfer. Epidemiological and economic modelling studies have shown that, in comparison to travel restrictions, applying intervention measures to interrupt local transmission within a country and investing into vaccine research and anti-viral stockpiling, is a more cost-effective and efficient use of resources for the containment of pandemics. A study investigating the perceived threat associated with pandemics showed that the subjective risk perception of people varies among countries. This influences human behaviour and should hence be considered during risk communication and implementation of pandemic control measures.

DISCUSSION

The basic prerequisites of an efficient pandemic management are operationalisable pandemic plans, subjected to regular exercises, backed by adequate resources and a sound health-care infrastructure. At international level cross-border co-operation and information exchange on infection control is the key to pandemic mitigation and containment. Strengthening surveillance systems at the international level, to allow the timely monitoring of infectious agents and outbreaks is essential. Transferring such outbreak information in real time into mathematical models and the resulting essential epidemiological information to policy makers would facilitate a more efficient use of scarce resources. Involvement of the public in decisions regarding the implementation of restrictive control measures which often curtail individual liberty is necessary for the acceptance and ultimate success of pandemic control.

Evaluation of national pandemic management policies-A hazard analysis of critical control points approach

Analyses of pandemic preparedness policies revealed weaknesses in control systems of European nations. This reinforces the need to support countries in their endeavours to prevent and contain pandemics. A Hazard Analysis and Critical Control Points (HACCP) was applied to a generic plan to identify weaknesses in pandemic management policies, in order to develop recommendations for improving national pandemic management systems. Policy components considered in our analysis are command and control, early case detection and disease surveillance, and community containment management. The main critical areas identified in national pandemic control were: communication systems among all institutions and levels involved in pandemic management, guidelines and regulations describing how key personal and institutions should operate during a pandemic, training and dissemination of information to health care personnel involved in outbreak management. The HACCP analysis highlighted the need for agreed communication structures, clear division of responsibilities and harmonised policy guidelines at all levels of pandemic management. Being prepared is the key to successfully coordinate and implement response measures when a pandemic emerges.

Impact of public health interventions in controlling the spread of SARS: modelling of intervention scenarios

A variety of intervention measures exist to prevent and control diseases with pandemic potential like SARS or pandemic influenza. They differ in their approach and effectiveness in reducing the number of cases getting infected. The effects of different intervention measures were investigated by a mathematical modelling approach, with comparisons based on the effective reproduction number (R(e)). The analysis showed that early case detection followed by strict isolation could control a SARS outbreak. Tracing close contacts of cases and contacts of exposed health care workers additionally reduces the R(e). Tracing casual contacts and measures aiming to decrease social interaction were less effective in reducing the number of SARS cases. The study emphasizes the importance of early identification and isolation of SARS cases to reduce the number of people getting infected. However, doing so transfers cases to health care facilities, making infection control measures in hospitals essential to avoid nosocomial spread. The modelling approach applied in this study is useful for analysing interactions of different intervention measures for reducing the R(e) of SARS.

Case-case study of a Salmonella outbreak: an epidemiologic method to analyse surveillance data

Routine infectious disease surveillance data has to be analysed quickly in order to prevent further disease transmission. This can be done by using epidemiological studies, such as case-control studies. However, these studies are complex to perform and susceptible for biases. An alternative is the case-case study design which is less prone to such limitations. So far mainly methodological publications of this study design exist. In this investigation, outbreak cases are compared with cases infected with the same disease. A Salmonella outbreak was analysed with a case-case study design in order to test the applicability of this method. The analysis showed significant associations to the consumption beef (OR 11.8; 95% CI 2.4-66.7; p<0.001) and pork (OR 8.44; 95% CI 1.7-46.4; p<0.001). A case-control study on the same outbreak confirmed these results. An infected control group is very comparable to the outbreak cluster, which limits selection and recall bias. However, the calculated OR has to be interpreted in context with the study design. The case-case study design has proven to be a useful tool to analyse surveillance data. It was easy to perform and had methodological benefits.

[Methods of infectious disease epidemiology for public health services: case control studies as bridge between practical work, surveillance and epidemiology]

Routine surveillance of infectious diseases is one important task of national public health services. Due to globalization the impact of international disease monitoring rises. The volume of traffic and trade is constantly increasing, which makes a spread of infectious diseases to distant places more likely then ever. This are challenges international infectious disease networks have to deal with. Thus, the role of investigation of disease outbreaks is not only relevant for local level; it furthermore prevents broader spread. To eliminate outbreak sources good epidemiological analyses have to be conducted. However, this often leads to extra time and personal resources. In addition classical studies, like case-control studies, underlay methodical limitations. Case-control studies, especially if conducted on the basis of notified cases from surveillance data, are susceptible to bias (like selection- and recall bias). Another study design, the case-case study (case-case comparison), provides an alternative, which is less affected by such limitations. In this approach a number of cases related within an outbreak, is compared with a group of infected individuals of the same disease, not belonging to the outbreak. Results from recently published studies lead to the assumption that this study design is adequate for the investigation of infectious disease outbreaks, captured by surveillance systems. The practical application of this study design makes it especially useful for local public health services and thus provides a bridge between surveillance, epidemiology and practical work in Public Health.