Ursula Panzner

A systematic review of the epidemiology of hepatitis E virus in Africa

BackgroundHepatitis E Virus (HEV) infection is a newly recognized serious threat to global public health and Africa is suspected to be among the most severely affected regions in the world. Understanding HEV epidemiology in Africa will expedite the implementation of evidence-based control policies aimed at preventing the spread of HEV including policies for the use of available resources such as HEV vaccines.MethodsHere we present a comprehensive review of HEV epidemiology in Africa based on published data. We searched for articles on HEV epidemiology in Africa from online databases such as PubMed, Scopus, and ISI Web of Science and critically reviewed appropriate publications to extract consistent findings, identify knowledge gaps, and suggest future studies.ResultsTaking a particularly high toll in pregnant women and their fetuses, HEV has infected human populations in 28 of 56 African countries. Since 1979, 17 HEV outbreaks have been reported about once every other year from Africa causing a reported 35,300 cases with 650 deaths.ConclusionsIn Africa, HEV infection is not new, is widespread, and the number of reported outbreaks are likely a significant underestimate. The authors suggest that this is a continent-wide public health problem that deserves the attention of local, regional and international agencies to implement control policies that can save numerous lives, especially those of pregnant women and their fetuses.

Incidence of invasive salmonella disease in sub-Saharan Africa: a multicentre population-based surveillance study

Summary Background Available incidence data for invasive salmonella disease in sub-Saharan Africa are scarce. Standardised, multicountry data are required to better understand the nature and burden of disease in Africa. We aimed to measure the adjusted incidence estimates of typhoid fever and invasive non-typhoidal salmonella (iNTS) disease in sub-Saharan Africa, and the antimicrobial susceptibility profiles of the causative agents. Methods We established a systematic, standardised surveillance of blood culture-based febrile illness in 13 African sentinel sites with previous reports of typhoid fever: Burkina Faso (two sites), Ethiopia, Ghana, Guinea-Bissau, Kenya, Madagascar (two sites), Senegal, South Africa, Sudan, and Tanzania (two sites). We used census data and health-care records to define study catchment areas and populations. Eligible participants were either inpatients or outpatients who resided within the catchment area and presented with tympanic (≥38·0°C) or axillary temperature (≥37·5°C). Inpatients with a reported history of fever for 72 h or longer were excluded. We also implemented a health-care utilisation survey in a sample of households randomly selected from each study area to investigate health-seeking behaviour in cases of self-reported fever lasting less than 3 days. Typhoid fever and iNTS disease incidences were corrected for health-care-seeking behaviour and recruitment. Findings Between March 1, 2010, and Jan 31, 2014, 135 Salmonella enterica serotype Typhi (S Typhi) and 94 iNTS isolates were cultured from the blood of 13 431 febrile patients. Salmonella spp accounted for 33% or more of all bacterial pathogens at nine sites. The adjusted incidence rate (AIR) of S Typhi per 100 000 person-years of observation ranged from 0 (95% CI 0–0) in Sudan to 383 (274–535) at one site in Burkina Faso; the AIR of iNTS ranged from 0 in Sudan, Ethiopia, Madagascar (Isotry site), and South Africa to 237 (178–316) at the second site in Burkina Faso. The AIR of iNTS and typhoid fever in individuals younger than 15 years old was typically higher than in those aged 15 years or older. Multidrug-resistant S Typhi was isolated in Ghana, Kenya, and Tanzania (both sites combined), and multidrug-resistant iNTS was isolated in Burkina Faso (both sites combined), Ghana, Kenya, and Guinea-Bissau. Interpretation Typhoid fever and iNTS disease are major causes of invasive bacterial febrile illness in the sampled locations, most commonly affecting children in both low and high population density settings. The development of iNTS vaccines and the introduction of S Typhi conjugate vaccines should be considered for high-incidence settings, such as those identified in this study. Funding Bill & Melinda Gates Foundation.

The Typhoid Fever Surveillance in Africa Program (TSAP): Clinical, Diagnostic, and Epidemiological Methodologies.

BACKGROUND New immunization programs are dependent on data from surveillance networks and disease burden estimates to prioritize target areas and risk groups. Data regarding invasive Salmonella disease in sub-Saharan Africa are currently limited, thus hindering the implementation of preventive measures. The Typhoid Fever Surveillance in Africa Program (TSAP) was established by the International Vaccine Institute to obtain comparable incidence data on typhoid fever and invasive nontyphoidal Salmonella (iNTS) disease in sub-Saharan Africa through standardized surveillance in multiple countries. METHODS Standardized procedures were developed and deployed across sites for study site selection, patient enrolment, laboratory procedures, quality control and quality assurance, assessment of healthcare utilization and incidence calculations. RESULTS Passive surveillance for bloodstream infections among febrile patients was initiated at thirteen sentinel sites in ten countries (Burkina Faso, Ethiopia, Ghana, Guinea-Bissau, Kenya, Madagascar, Senegal, South Africa, Sudan, and Tanzania). Each TSAP site conducted case detection using these standardized methods to isolate and identify aerobic bacteria from the bloodstream of febrile patients. Healthcare utilization surveys were conducted to adjust population denominators in incidence calculations for differing healthcare utilization patterns and improve comparability of incidence rates across sites. CONCLUSIONS By providing standardized data on the incidence of typhoid fever and iNTS disease in sub-Saharan Africa, TSAP will provide vital input for targeted typhoid fever prevention programs.

Report on the International Symposium on Hepatitis E, Seoul, South Korea, 2010.

Hepatitis E virus (HEV), transmitted through the fecal–oral route, was first identified during waterborne epidemics of acute hepatitis in Kashmir and New Delhi, India, in 1980 (1–3). The virus was later characterized as a spherical virion of 27–34 nm in diameter with a nonenveloped, positive-sense, single-stranded RNA genome of ≈7.2 kb (4) and classified into 4 genotypes (1,2,5,6) that appear to have specific global distributions (4). Genotypes 1 and 2 are primarily responsible for HEV infections in humans; genotypes 3 and 4 can be found in animals and humans. Clinical manifestations of HEV infection range from asymptomatic to fulminant hepatic failure and death. Symptomatic episodes are common in adolescents and adults; pregnant women have the highest attack rates (1). Although HEV infection results in low case-fatality rates (0.5%–4.0%) in the general population, HEV causes death in 10%–42% of infected pregnant women (5,6). HEV epidemics occur primarily in areas with poor hygiene and poor sanitation, including countries in Asia, the Middle East, Africa, and Latin America. Despite the growing evidence of global effects of HEV, awareness of the public health implications of HEV infection remains low because of questions regarding its epidemiology; its health, economic, and social costs; and its virology and pathogenesis. The disease and its case-fatality rate probably are underestimated because HEV infections are not clinically distinguishable from those caused by other hepatitis viruses. Validated, commercially available diagnostic assays are needed, and existing assays vary substantially for sensitivity (72%–98%) and specificity (79%– 96%). During September 15–16, 2010, the International Vaccine Institute and the World Health Organization (WHO), with sponsorship from the US Centers for Disease Control and Prevention and the Bill & Melinda Gates Foundation, hosted the International Symposium on Hepatitis E in Seoul, South Korea. International experts (Table), including virologists, immunologists, molecular biologists, epidemiologists, clinicians, and policy makers, gathered to review published and unpublished epidemiologic, clinical, and laboratory data and to discuss control strategies. Participants considered, in particular, the impact of HEV, the 2 hepatitis E vaccine candidates, and outlined activities to characterize hepatitis E epidemiology and support vaccine development and other prevention strategies. Table Investigators who presented at the International Symposium on Hepatitis E, Seoul, South Korea, September 15–16, 2010 The symposium presenters shared data that showed that HEV infection is endemic to industrialized and developing countries. WHO shared results of its 2010 Global Burden of Diseases, Injuries and Risk Factors study, which found that 63 countries had reported outbreaks or sporadic cases and 73 countries reported seroprevalence >10%. During the session on the significance of hepatitis E as a public health threat in developing and other countries, HEV genotypes 1 and 2 were reported to be associated with large epidemics and high case-fatality rates, and to have induced ≈15 million symptomatic and 13 million asymptomatic cases in 2005. Other data presented indicated that the impact of HEV is high in many of the world’s largest population settings with poor hygiene and sanitation, particularly countries in Africa, Latin America, and southern and central Asia. Sporadic cases were reported in industrialized countries (e.g., Germany, Sweden, and the United States), and serologic studies indicated that prevalence in these populations was higher than previously thought. In industrialized countries, autochthonous cases are caused by genotypes 3 and 4. These genotypes are associated with asymptomatic and chronic disease and are probably associated with zoonotic transmission through ingestion of HEV-infected meat. Illness caused by genotype 1 in these countries was imported. After establishing the epidemiology of HEV, the symposium focused on the loss of life it causes. Pregnant women, immunosuppressed patients, and persons who have chronic liver disease constitute high-risk groups. Presenters discussed studies conducted in Bangladesh during 2001–2006 and Uganda during 2007 that reported pregnant women had the highest rate of death from HEV. In the Uganda outbreak, the case-fatality rate for pregnant women was 8.3% (1.6% of overall deaths). Suggested risk factors were poor sanitation, hygiene, and living conditions. Vertical transmission (mother to child) was also suggested, although further investigation is needed. Chronic liver disease has been associated with high rates of illness and death from HEV superinfection, and chronic HEV-associated hepatitis can develop in immunosuppressed patients. Data based on disease modeling presented at the symposium suggest that HEV is associated with 271,000 deaths annually, which is 10-fold more than the annual number of deaths from hepatitis A virus. Because many who die are young adults, many life-years are lost to HEV illness. Further estimates on the basis of modeling predict an annual global impact caused by genotypes 1 and 2 of 21.6 million symptomatic cases and 12,203 stillbirths. The actual numbers might be larger if genotypes 3 and 4 also contribute meaningfully. As main preventive tools, 2 vaccines were discussed: the recombinant HEV vaccine developed by GlaxoSmithKline (Raleigh-Durham, NC, USA), and the recombinant HEV 239 vaccine developed by Xiamen Innovax Biotech (Xiamen, People’s Republic of China). Although both vaccines were shown to be safe and efficacious (protective efficacy >90%), further studies are needed to demonstrate safety and long-term efficacy in high-risk persons and populations living in HEV-endemic areas. Besides further clinical development of these vaccines, public health demand, feasibility, and cost-effectiveness must be demonstrated and financing made available in developing countries. Furthermore, these tasks must be accomplished in light of limited interest and resources for HEV vaccine development in industrialized countries. In conclusion, participants made an international call to action against HEV infection and agreed that advocacy is needed to increase awareness of hepatitis E as a disease that can adversely affect public health, and to position hepatitis E as a neglected disease of the poor, which is potentially preventable by vaccines. Priorities are to improve quality and availability of HEV diagnostics and develop standardized surveillance methods in the absence of a diagnostic standard. Participants also prioritized research to demonstrate the applicability of vaccine candidates and data collection required for their WHO prequalification. Looking ahead, when hepatitis E vaccines become available, vaccine demonstration projects should be implemented in well-characterized populations and supported by reliable diagnostic tools. Symposium participants recommended the formation of an international hepatitis E collaboration to provide a multicountry, multidisciplinary platform for initiatives in research, policy, and advocacy. This collaboration would initially focus on supporting the development and evaluation of HEV diagnostics; developing standardized population- and hospital-based disease surveillance to conduct epidemiologic studies of high-risk populations; developing partnerships with industry to facilitate clinical trials of candidate hepatitis E vaccines and study cost-effectiveness of different vaccine strategies; and increasing global awareness, especially of opinion leaders and decision makers, on the threat of hepatitis E infection.

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.

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.

Variations of Invasive Salmonella Infections by Population Size in Asante Akim North Municipal, Ghana

BACKGROUND The Typhoid Fever Surveillance in Africa Program (TSAP) estimated adjusted incidence rates (IRs) for Salmonella enterica serovar Typhi and invasive nontyphoidal S. enterica serovars (iNTS) of >100 cases per 100 000 person-years of observation (PYO) for children aged <15 years in Asante Akim North Municipal (AAN), Ghana, between March 2010 and May 2012. We analyzed how much these rates differed between rural and urban settings. METHODS Children recruited at the Agogo Presbyterian Hospital and meeting TSAP inclusion criteria were included in the analysis. Towns with >32 000 inhabitants were considered urban; towns with populations <5200 were considered rural. Adjusted IRs for Salmonella bloodstream infections were estimated for both settings. Setting-specific age-standardized incidence rates for children aged <15 years were derived and used to calculate age-standardized rate ratios (SRRs) to evaluate differences between settings. RESULTS Eighty-eight percent (2651/3000) of recruited patients met inclusion criteria and were analyzed. IRs of Salmonella bloodstream infections in children <15 years old were >100 per 100 000 PYO in both settings. Among rural children, the Salmonella Typhi and iNTS rates were 2 times (SRR, 2.2; 95% confidence interval [CI], 1.3-3.5) and almost 3 times (SRR, 2.8; 95% CI, 1.9-4.3) higher, respectively, than rates in urban children. CONCLUSIONS IRs of Salmonella bloodstream infections in children <15 years old in AAN, Ghana, differed by setting, with 2 to nearly 3 times higher rates in the less populated setting. Variations in the distribution of the disease should be considered to implement future studies and intervention strategies.

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.

Utilization of Healthcare in the Typhoid Fever Surveillance in Africa Program

BACKGROUND Assessing healthcare utilization is important to identify weaknesses of healthcare systems, to outline action points for preventive measures and interventions, and to more accurately estimate the disease burden in a population. METHODS A healthcare utilization survey was developed for the Typhoid Fever Surveillance in Africa Program (TSAP) to adjust incidences of salmonellosis determined through passive, healthcare facility-based surveillance. This cross-sectional survey was conducted at 11 sites in 9 sub-Saharan African countries. Demographic data and healthcare-seeking behavior were assessed at selected households. Overall and age-stratified percentages of each study population that sought healthcare at a TSAP healthcare facility and elsewhere were determined. RESULTS Overall, 88% (1007/1145) and 81% (1811/2238) of the population in Polesgo and Nioko 2, Burkina Faso, respectively, and 63% (1636/2590) in Butajira, Ethiopia, sought healthcare for fever at any TSAP healthcare facility. A far smaller proportion-namely, 20%-45% of the population in Bissau, Guinea-Bissau (1743/3885), Pikine, Senegal (1473/4659), Wad-Medani, Sudan (861/3169), and Pietermaritzburg, South Africa (667/2819); 18% (483/2622) and 9% (197/2293) in Imerintsiatosika and Isotry, Madagascar, respectively; and 4% (127/3089) in Moshi, Tanzania-sought healthcare at a TSAP healthcare facility. Patients with fever preferred to visit pharmacies in Imerintsiatosika and Isotry, and favored self-management of fever in Moshi. Age-dependent differences in healthcare utilization were also observed within and across sites. CONCLUSIONS Healthcare utilization for fever varied greatly across sites, and revealed that not all studied populations were under optimal surveillance. This demonstrates the importance of assessing healthcare utilization. Survey data were pivotal for the adjustment of the programs estimates of salmonellosis and other conditions associated with fever.

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.