Sentinel surveillance for influenza among severe acute respiratory infection and acute febrile illness inpatients at three hospitals in Ghana

Epidemiology of respiratory pathogens in patients with acute respiratory infections during the COVID-19 pandemic and after easing of COVID-19 restrictions

We aimed to investigate the epidemiological characteristics of non-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) respiratory pathogens among patients with acute respiratory infections (ARIs) in Shijiazhuang, China, during the coronavirus disease 2019 (COVID-19) pandemic (January 2021--December 2022) and after the relaxation of COVID-19 restrictive measures (January 2022--December 2023). This retrospective study enrolled 6,633 ARIs patients who visited the Hebei General Hospital between 2021- and 2023. Nasopharyngeal swabs samples were collected for multiplex PCR detection of 13 common respiratory pathogens. Respiratory pathogens were detected in 31.58% of individuals diagnosed with ARIs, whileereas a co-infection with multiple pathogens was observed in 8.5% of the ARI patients. In the years 2021 and 2022, 326 (27.63%) and 283 (24.38%) respiratory pathogens were found to be positive, respectively, during the COVID-19 pandemic. However, in 2023, subsequent to the easing of COVID-19 restrictions, the positivity rate significantly rose to 34.62%, with 4,292 cases identified. The majority of positive cases over the last three3 years were concentrated in patients under 14 years old. The predominant pathogens identified were human rhinovirus (HRVs) (15.08%) in 2021, mycoplasma pneumonia (MP) (6.46%) in 2022, and influenza A virus (FluA) (11.35%) in 2023. Seasonal prevalence patterns of most pathogens were affected, except for parainfluenza virus (PIV). There was a simultaneous increase in the positive cases and positivity rates of FluA and adenovirus (ADV) Iin 2023, compared to 2021 and 2022. Additionally, the infection rates of respiratory syncytial virus (RSV), MP, and coronavirus (CoV) in 2023 either exceeded or were comparable to those in 2021 and 2022. Conversely, the positivity rates of PIV, RVs, metapneumovirus (MPV), and influenza B virus (FluB) were lower in 2023 compared to 2021 or 2022.

IMPORTANCE

The implementation of strict non-pharmaceutical interventions (NPIs) during the coronavirus disease 2019 (COVID-19) pandemic may lead to changes in the epidemiological features of respiratory pathogens, as well as the occurrence of immune debt, potentially causing a resurgence in respiratory pathogen activity following the easing of strict NPIs measures. There are limited reports on the epidemiological characteristics of respiratory pathogens among patients of all ages with acute respiratory infections (ARIs) during the COVID-19 pandemic and after the easing of COVID-19 restrictions. Our study investigated the epidemiology of 13 respiratory pathogens in Shijiazhuang, China, from January 2021 to December 2023. Thisese data isare crucial for the ongoing surveillance of epidemiological shifts in respiratory pathogens during and post the -COVID-19 pandemic, and serves as a scientific foundation for the prevention and management of ARIs.

Effect of antipyretics on performance of influenza surveillance in Ghana

BACKGROUND

The World Health Organization's case definition for influenza-like illness (ILI) includes a measured temperature of ≥38°C. We conducted this study to assess the effect of antipyretics on performance of ILI surveillance in Ghana.

METHODS

A cross-sectional study was conducted in two districts of Ghana from September 2013 to May 2014. We collected epidemiological data and respiratory specimens from an expanded ILI case definition, which included patients presenting to health facilities with measured temperature ≥38°C or reported fever (but afebrile at the time of evaluation), and cough, with onset in the last 10 days. Specimens were tested for influenza viruses by real time reverse-transcription polymerase chain reaction.

RESULTS

Of 321 participants who met our expanded ILI case definition, 236 presented with temperature of <38°C but reported subjective fever. Of these, 17% (39/236) were positive for influenza virus; Of those with fever ≤38°C who took antipyretics, 21%(16/77) were positive for influenza, compared with 14%(23/159) of those who did not take antipyretics. The addition of subjective fever to the standard ILI case definition captured approximately an additional 57% influenza cases but also required testing of approximately four times as many patients. However, including those without fever on presentation that had taken antipyretics found an additional 23% of Influenza cases and only two times as much testing.

CONCLUSION

Depending on the goals of surveillance (monitoring virus circulation or determining disease burden) and available resources, a more sensitive case definition including subjective fever and history of use of antipyretics may be warranted.

Sentinel surveillance for influenza A viruses in Lahore District Pakistan in flu season 2015-2016

Background

Influenza A virus (IAV) remains an important global public health threat with limited epidemiological information available from low-and-middle-income countries. The major objective of this study was to describe the proportions, temporal and spatial distribution, and demographic and clinical characteristics of IAV positive patients with influenza like illness (ILI) and severe acute respiratory illness (SARI) in Lahore, Pakistan.

Methods

Prospective surveillance was established in a sentinel hospital from October 2015 to May 2016. All eligible outpatients and inpatients with ILI or SARI were enrolled in the study. Nasal and/or throat swabs were collected along with clinico-epidemiological data. Samples were tested by real-time RT-PCR (rRT-PCR) to identify IAV and subtype. The descriptive analysis of data was done in R software.

Results

Out of 311 enrolled patients, 284 (91.3%) were ILI and 27 (8.7%) were SARI cases. A distinct peak of ILI and SARI activity was observed in February. Fifty individuals (16%) were positive for IAV with peak positivity observed in December. Of 50 IAV, 15 were seasonal H3N2, 14 were H1N1pdm09 and 21 were unable to be typed. The majority of IAV positive cases (98%) presented with current or history of fever, 88% reported cough and 82% reported sore throat. The most common comorbidities in IAV positive cases were hepatitis C (4%), obesity (4%) and tuberculosis (6%). The highest incidence of patients reporting to the hospital was seen three days post symptoms onset (66/311) with 14 of these (14/66) positive for IAV.

Conclusion

Distinct trends of ILI, SARI and IAV positive cases were observed which can be used to inform public health interventions (vaccinations, hand and respiratory hygiene) at appropriate times among high-risk groups. We suggest sampling from both ILI and SARI patients in routine surveillance as recommended by WHO.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-07021-7.

The first epidemiological and virological influenza surveillance in the Republic of Guinea revealed the predominance of influenza A/H3N2 and B Victoria viruses

Little is known about respiratory viruses infection in Guinea. Influenza surveillance has not been implemented in Guinea mainly because of the paucity of laboratory infrastructure and capacity. This paper presents the first influenza surveillance data in Guinea.Swabs were obtained from August 2018 through December 2019 at influenza sentinel sites and transported to the Institut National de Santé Publique for testing. Ribonucleic acid was extracted and tested for the presence of influenza A and B by real-time reverse transcription-polymerase chain reaction (RT-PCR). Positive samples were further characterised to determine the subtypes and lineages of influenza viruses.A total of 862 swabs were collected and tested. Twenty-three per cent of samples tested positive for influenza A and B viruses. Characterisation of positive specimens identified influenza A/H1N1pmd09 (2.5%), influenza A/H3N2 (57.3%), influenza B/Victoria lineage (36.7%) and 7 (3.5%) influenza B with undetermined lineage. Influenza B virus activity clustered in August through November while influenza A/H3N2 displayed two clusters of activities that appeared in May through August and November through December.For the first time in Guinea, the epidemiology, diversity and period of circulation of influenza viruses were studied. The results indicate the predominance and the periods of activities of influenza B Victoria lineage and influenza A/H3N2 which are important information for preventive strategies. It is warranted to extend the influenza surveillance to other parts of Guinea to better understand the epidemiology of the viruses and monitor the emergence of influenza strains with pandemic potential.

The epidemiology of seasonal influenza after the 2009 influenza pandemic in Africa: a systematic review

Background

Influenza infection is a serious public health problem that causes an estimated 3 to 5 million cases and 250,000 deaths worldwide every year. The epidemiology of influenza is well-documented in high- and middle-income countries, however minimal effort had been made to understand the epidemiology, burden and seasonality of influenza in Africa. This study aims to assess the state of knowledge of seasonal influenza epidemiology in Africa and identify potential data gaps for policy formulation following the 2009 pandemic.

Method

We reviewed articles from Africa published into four databases namely: MEDLINE (PubMed), Google Scholar, Cochrane Library and Scientific Research Publishing from 2010 to 2019.

Results

We screened titles and abstracts of 2070 studies of which 311 were selected for full content evaluation and 199 studies were considered. Selected articles varied substantially on the basis of the topics they addressed covering the field of influenza surveillance (n=80); influenza risk factors and co-morbidities (n=15); influenza burden (n=37); influenza vaccination (n=40); influenza and other respiratory pathogens (n=22) and influenza diagnosis (n=5).

Conclusion

Significant progress has been made since the last pandemic in understanding the influenza epidemiology in Africa. However, efforts still remain for most countries to have sufficient data to allow countries to prioritize strategies for influenza prevention and control.

Antigenic drift of hemagglutinin and neuraminidase in seasonal H1N1 influenza viruses from Saudi Arabia in 2014 to 2015

Antigenic drift of the hemagglutinin (HA) and neuraminidase (NA) proteins of the influenza virus cause a decrease in vaccine efficacy. Since the information about the evolution of these viruses in Saudi is deficient so we investigated the genetic diversity of circulating H1N1 viruses. Nasopharyngeal aspirates/swabs collected from 149 patients hospitalized with flu-like symptoms during 2014 and 2015 were analyzed. Viral RNA extraction was followed by a reverse transcription-polymerase chain reaction and genetic sequencing. We analyzed complete gene sequences of HA and NA from 80 positive isolates. Phylogenetic analysis of HA and NA genes of 80 isolates showed similar topologies and co-circulation of clades 6b. Genetic diversity was observed among circulating viruses belonging to clade 6B.1A. The amino acid residues in the HA epitope domain were under purifying selection. Amino acid changes at key antigenic sites, such as position S101N, S179N (antigenic site-Sa), I233T (antigenic site-Sb) in the head domain might have resulted in antigenic drift and emergence of variant viruses. For NA protein, 36% isolates showed the presence of amino acid changes such as V13I (n = 29), I314M (n = 29) and 12% had I34V (n = 10). However, H257Y mutation responsible for resistance to neuraminidase inhibitors was missing. The presence of amino acid changes at key antigenic sites and their topologies with structural mapping of residues under purifying selection highlights the importance of antigenic drift and warrants further characterization of recently circulating viruses in view of vaccine effectiveness. The co-circulation of several clades and the predominance of clade 6B.1 suggest multiple introductions in Saudi.

Exposure of domestic swine to influenza A viruses in Ghana suggests unidirectional, reverse zoonotic transmission at the human-animal interface

Influenza A viruses (IAVs) have both zoonotic and anthroponotic potential and are of public and veterinary importance. Swine are intermediate hosts and 'mixing vessels' for generating reassortants, progenies of which may harbour pandemic propensity. Swine handlers are at the highest risk of becoming infected with IAVs from swine but there is little information on the ecology of IAVs at the human-animal interface in Africa. We analysed and characterized nasal and throat swabs from swine and farmers respectively, for IAVs using RT-qPCR, from swine farms in the Ashanti region, Ghana. Sera were also analysed for IAVs antibodies and serotyped using ELISA and HI assays. IAV was detected in 1.4% (n = 17/1,200) and 2.0% (n = 2/99) of swine and farmers samples, respectively. Viral subtypes H3N2 and H1N1pdm09 were found in human samples. All virus-positive swine samples were subtyped as H1N1pdm09 phylogenetically clustering closely with H1N1pdm09 that circulated among humans during the study period. Phenotypic markers that confer sensitivity to Oseltamivir were found. Serological prevalence of IAVs in swine and farmers by ELISA was 3.2% (n = 38/1,200) and 18.2% (n = 18/99), respectively. Human H1N1pdm09 and H3N2 antibodies were found in both swine and farmers sera. Indigenous swine influenza A viruses and/or antibodies were not detected in swine or farmers samples. Majority (98%, n = 147/150) of farmers reported of not wearing surgical mask and few (4%, n = 6) reported to wear gloves when working. Most (n = 74, 87.7%) farmers reported of working on the farm when experiencing influenza-like illness. Poor husbandry and biosafety practices of farmers could facilitate virus transmission across the human-swine interface. Farmers should be educated on the importance of good farm practices to mitigate influenza transmission at the human-animal interface.

Comparison of viral and epidemiological profiles of hospitalized children with severe acute respiratory infection in Beijing and Shanghai, China

Background

No comparison data have been reported on viral and epidemiological profiles of hospitalized children with severe acute respiratory infection (SARI) in Beijing or Shanghai, China.

Methods

We collected 700 nasopharyngeal aspirates (NPA) from hospitalized children with SARI in Beijing (northern China) and Shanghai (southern China). Multiple respiratory viruses (including 15 common viruses) were screened by validated polymerase chain reaction (PCR) or real-time reverse transcription-PCR assays and confirmed by sequencing. Demographic data and the distribution of viral infections were also examined.

Results

Of 700 samples, 547 (78.1%) tested positive for viral infections. The picornaviruses (PIC), which included rhinovirus (RV) and enterovirus (EV), were the most common (34.0%), followed by respiratory syncytial virus (RSV) (28.3%), human bocavirus (HBoV) (19.1%), adenovirus (ADV) (13.7%), human coronaviruses (HCoV) (10.7%), influenza A and B (8.9%), parainfluenza virus (PIV 1–3) (7.9%), and human metapneumovirus (HMPV) (5.0%). PIC (RV/EV) and RSV were the most prevalent etiological agents of SARI in both cities. The total and age-matched prevalence of RSV, HCoV, and hMPV among SARI children under 5 years old were significantly higher in Beijing than in Shanghai. Different age and seasonal distribution patterns of the viral infections were found between Beijing and Shanghai.

Conclusions

Viral infection was tested and shown to be the most prevalent etiological agent among children with SARI in either the Beijing or the Shanghai area, while showing different patterns of viral and epidemiological profiles. Our findings provide a better understanding of the roles of geographic location and climate in respiratory viral infections in hospitalized children with SARI.

Prevalence and determinants of Acute Lower Respiratory Infections among children under-five years in sub-Saharan Africa: Evidence from demographic and health surveys

Acute Lower Respiratory Infections (ALRIs) account for 5.8 million deaths globally and 50% of these deaths occur in sub-Saharan Africa. In this paper, we examined the prevalence and determinants of ALRIs among children under-five years in 28 sub–Saharan African countries. We used data from the most recent (2011–2016) Demographic and Health Surveys of the 28 countries. Women aged 15–49 (N = 13,495) with children under-five years participated in the study. Data were extracted and analysed using STATA version 14.2. Bivariate and multivariate analyses were done to establish associations between the outcome and explanatory variables. The prevalence of ALRI for all the countries was 25.3%. Congo (39.8%), Gabon (38.1%), Lesotho (35.2%), and Tanzania (35.2%) were the countries with the highest prevalence of ALRIs. The results from the multivariate analyses showed that children aged 24–59 months (AOR = 1.15; 95% CI = 1.04–1.28), and children who received intestinal parasite in the 6 months preceding the survey (AOR = 1.11; 95% CI = 1.02–1.22) had higher odds of developing ALRIs. However, children whose mothers were employed (AOR = 0.77; 95% CI = 0.64–0.94) and those whose households used improved toilet facilities (AOR = 0.72; 95% CI = 0.64–0.97) had lower odds of contracting ALRIs. Our findings underscore the need for stakeholders in health in the various sub-Saharan African countries, especially those worst affected by ALRIs to implement programmes and develop policies at different levels aimed at reducing infections among children under-five years. Such strategies should specifically focus on improving the administration of medications for intestinal worms, health education to mothers with children under five on ALRIs and improving the sanitation situations of households through the provision of improved toilet facilities.

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We examined the prevalence and determinants of Acute Lower Respiratory Infections (ALRIs) among children under-five years in sub–Sahara Africa.

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ALRIs account for 5.8 million deaths globally.

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The prevalence of ALRI is 25.3% in sub-Sahara Africa.

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Children aged 24–59 months had higher odds of developing ALRIs.

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Employed mothers and improved toilet facility are protective factors against ALRIs.

Viral prevalence, clinical profiles and comparison of severity scores for predicting the mortality of adults with severe acute respiratory infections

Background/aim

The aim of this study was to determine the accuracy of severity scores for predicting the 28-day mortality among adults with severe acute respiratory infection (SARI) admitted to the emergency department.

Materials and methods

This study included 159 consecutive adult patients with SARI admitted to the emergency department of a tertiary hospital. A standard form was filled out in order to record demographic information, clinical parameters, laboratory tests, and radiographic findings of the patients. CURB-65, PSI, SIRS, qSOFA, SOFA and APACHE II scores were compared between the survivor and nonsurvivor groups.

Results

Of 159 patients included in the study, 38.4% were positive for respiratory viruses and 28.3% were positive for influenza viruses. 35.8% of the patients were admitted to an intensive care unit (ICU) and the mortality rate was 36.5%. The area under the receiver operating characteristic curve of CURB-65, PSI, SIRS criteria, qSOFA, SOFA and APACHE II scores were 0.717, 0.712, 0.607, 0.683, 0.755, and 0.748, respectively in predicting mortality and 0.759, 0.744, 0.583, 0.728, 0.741, and 0.731, respectively in predicting ICU admission.

Conclusion

SOFA and APACHE II were more accurate than SIRS in predicting the 28-day mortality among adults with SARI. There was no significant difference among these scores in terms of other multivariate comparisons.

Respiratory Viral Infection: An Underappreciated Cause of Acute Febrile Illness Admissions in Southern Sri Lanka

The contribution of respiratory viruses to acute febrile illness (AFI) burden is poorly characterized. We describe the prevalence, seasonality, and clinical features of respiratory viral infection among AFI admissions in Sri Lanka. We enrolled AFI patients ≥ 1 year of age admitted to a tertiary care hospital in southern Sri Lanka, June 2012-October 2014. We collected epidemiologic/clinical data and a nasal or nasopharyngeal sample that was tested using polymerase chain reaction (Luminex NxTAG, Austin, TX). We determined associations between weather data and respiratory viral activity using the Spearman correlation and assessed respiratory virus seasonality using a Program for Appropriate Technology definition. Bivariable and multivariable regression analyses were conducted to identify features associated with respiratory virus detection. Among 964 patients, median age was 26.2 years (interquartile range 14.6-39.9) and 646 (67.0%) were male. One-fifth (203, 21.1%) had respiratory virus detected: 13.9% influenza, 1.4% human enterovirus/rhinovirus, 1.4% parainfluenza virus, 1.1% respiratory syncytial virus, and 1.1% human metapneumovirus. Patients with respiratory virus identified were younger (median 9.8 versus 27.7 years, P < 0.001) and more likely to have respiratory signs and symptoms. Influenza A and respiratory viral activity peaked in February-June each year. Maximum daily temperature was associated with influenza and respiratory viral activity (P = 0.03 each). Patients with respiratory virus were as likely as others to be prescribed antibiotics (55.2% versus 52.6%, P = 0.51), and none reported prior influenza vaccination. Respiratory viral infection was a common cause of AFI. Improved access to vaccines and respiratory diagnostics may help reduce disease burden and inappropriate antibiotic use.

Strengthening laboratory surveillance of viral pathogens: Experiences and lessons learned building next-generation sequencing capacity in Ghana

OBJECTIVE

To demonstrate the feasibility of applying next-generation sequencing (NGS) in medium-resource reference laboratories in Africa to enhance global disease surveillance.

METHODS

A training program was developed to support implementation of NGS at Noguchi Memorial Institute for Medical Research (NMIMR), University of Ghana. The program was divided into two training stages, first at the Centers for Disease Control and Prevention (CDC) in Atlanta, GA, followed by on-site training at NMIMR for a larger cohort of scientists.

RESULTS

Self-assessment scores for topics covered during the NGS training program were higher post-training relative to pre-training. During the NGS Training II session at NMIMR, six enterovirus isolates from acute flaccid paralysis cases in Ghana were successfully sequenced by trainees, including two echovirus 6, two echovirus 11 and one echovirus 13. Another genome was an uncommon type (EV-B84), which has not been reported in Africa since its initial discovery from a Côte d'Ivoire specimen in 2003.

CONCLUSIONS

The success at NMIMR provides an example of how to approach transferring of NGS methods to international laboratories. There is great opportunity for collaboration between institutes that have genomics expertise to ensure effectiveness and long-term success of global NGS capacity building programs.

The significance of human respiratory syncytial virus (HRSV) in children from Ghana with acute lower respiratory tract infection: A molecular epidemiological analysis, 2006 and 2013-2014

Background

Acute lower respiratory tract infection (ALRI) is a leading cause of childhood morbidity and mortality in developing countries. Globally, human respiratory syncytial virus (HRSV) is the most common pathogen of ALRI in infants and children. However, age-stratified HRSV disease burden data are largely absent from Africa, which is a key gap in informing an evidence-based recommendation for the introduction of an HRSV vaccine by the WHO.

Methods

This study investigated the presence of HRSV in respiratory specimens from 552 children <5 years old with ALRI from Accra, Ghana in 2006 and 2013–2014 by real-time PCR. Of HRSV-positive samples the second hypervariable region of the viral G protein gene was sequenced and analyzed for phylogeny, characteristic amino acid substitutions, and potential glycosylation patterns. Further, HRSV infections have been characterized by age, symptoms and timely occurrence.

Results

HRSV was observed in 23% (127/552) of the children with ALRI, with the highest incidence in infants younger than one year (33%, 97/295, p = 0.013). Within the observed seasonal circulation time of HRSV from June (mid-wet season) to December (beginning of the dry season) the incidence of ALRI due to HRSV was as high as 46% (125/273). HRSV disease was significantly associated with (broncho-) pneumonia, bronchiolitis, LRTI, and difficulty in breathing. Phylogenetic characterization of HRSV strains from Ghana identified the circulation of the currently worldwide prevailing genotypes ON1 and BA9, and shows evidence of an independent molecular evolution of ON1 and BA9 strains in Ghana resulting in potentially new subgenotypes within ON1 and BA9, provisionally named ON1.5, ON1.6, and BA9-IV.

Conclusion

This study addresses important knowledge gaps in the forefront of introducing the HRSV vaccine by providing information on the molecular evolution and incidence of HRSV in Accra (Ghana, Africa).

Preliminary results of official influenza and acute respiratory infection surveillance in two towns of Burkina Faso, 2013-2015

Background

In 2010, influenza, influenza-like illness (ILI) and acute respiratory infection (ARI) surveillance was established by the government of Burkina Faso. We provide preliminary descriptive results from this surveillance activity.

Methods

The study period was 2013 through 2015. Two primary healthcare facilities in Bobo-Dioulasso district reported ILI in outpatients. Influenza virology, using reverse transcription-polymerase chain reaction (rRT-PCR), was available for a proportion of ILI patients. One hospital, in the capital Ouagadougou, reported ARI in both outpatients and inpatients (hospitalized). Inpatients admitted with ARI were considered severe ARI (SARI). We estimated the proportion of primary care outpatient visits that were ILI, and the proportion of those that were due to influenza, by age. We estimated the proportion of hospital outpatient visits that were ARI and the proportion of those that were SARI, by age.

Results

Among combined outpatient visits in the Bobo-Dioulasso facilities, 19.6% were for ILI. One half (49.9%) of outpatient visits in infants and 30.9% in 1–4 year-olds were ILI. Among ILI outpatient visits 14.8% were due to influenza virus and, of these, 58.5% were type A and 41.5% type B. At the Ouagadougou hospital, 6.7% of outpatient visits were ARI, and 22.3% of those were SARI. The highest proportions of ARI were among infants (19.8%) and 1–4 year-olds (16.0%). The proportion of ARI that was SARI was highest among ≥15 year-olds (31.5%) followed by 1–4 year-olds (22.4%). Overall, 4.1% of SARI patients died.

Conclusions

These preliminary data indicate the importance of respiratory infections among health care attendances in Burkina Faso, and influenza may be an important contributor to these.

Using a hospital admission survey to estimate the burden of influenza-associated severe acute respiratory infection in one province of Cambodia-methods used and lessons learned

Background

Understanding the burden of influenza‐associated severe acute respiratory infection (SARI) is important for setting national influenza surveillance and vaccine priorities. Estimating influenza‐associated SARI rates requires hospital‐based surveillance data and a population‐based denominator, which can be challenging to determine.

Objectives

We present an application of the World Health Organization's recently developed manual (WHO Manual) including hospital admission survey (HAS) methods for estimating the burden of influenza‐associated SARI, with lessons learned to help others calculate similar estimates.

Methods

Using an existing SARI surveillance platform in Cambodia, we counted influenza‐associated SARI cases during 2015 at one sentinel surveillance site in Svay Rieng Province. We applied WHO Manual‐derived methods to count respiratory hospitalizations at all hospitals within the catchment area, where 95% of the sentinel site case‐patients resided. We used HAS methods to adjust the district‐level population denominator for the sentinel site and calculated the incidence rate of influenza‐associated SARI by dividing the number of influenza‐positive SARI infections by the adjusted population denominator and multiplying by 100 000. We extrapolated the rate to the provincial population to derive a case count for 2015. We evaluated data sources, detailed steps of implementation, and identified lessons learned.

Results

We estimated an adjusted influenza‐associated 2015 SARI rate of 13.5/100 000 persons for the catchment area of Svay Rieng Hospital and 77 influenza‐associated SARI cases in Svay Rieng Province after extrapolation.

Conclusions

Methods detailed in the WHO Manual and operationalized successfully in Cambodia can be used in other settings to estimate rates of influenza‐associated SARI.

Revision of clinical case definitions: influenza-like illness and severe acute respiratory infection

The formulation of accurate clinical case definitions is an integral part of an effective process of public health surveillance. Although such definitions should, ideally, be based on a standardized and fixed collection of defining criteria, they often require revision to reflect new knowledge of the condition involved and improvements in diagnostic testing. Optimal case definitions also need to have a balance of sensitivity and specificity that reflects their intended use. After the 2009-2010 H1N1 influenza pandemic, the World Health Organization (WHO) initiated a technical consultation on global influenza surveillance. This prompted improvements in the sensitivity and specificity of the case definition for influenza - i.e. a respiratory disease that lacks uniquely defining symptomology. The revision process not only modified the definition of influenza-like illness, to include a simplified list of the criteria shown to be most predictive of influenza infection, but also clarified the language used for the definition, to enhance interpretability. To capture severe cases of influenza that required hospitalization, a new case definition was also developed for severe acute respiratory infection in all age groups. The new definitions have been found to capture more cases without compromising specificity. Despite the challenge still posed in the clinical separation of influenza from other respiratory infections, the global use of the new WHO case definitions should help determine global trends in the characteristics and transmission of influenza viruses and the associated disease burden.

Burden of influenza among hospitalized febrile children in Ghana

BACKGROUND

Influenza surveillance data from Africa indicate a substantial disease burden with high mortality. However, local influenza data from district hospitals with limited laboratory facilities are still scarce.

OBJECTIVES

To identify the frequency and seasonal distribution of influenza among hospitalized febrile children in a rural hospital in Ghana and to describe differential diagnoses to other severe febrile infections.

METHODS

Between January 2014 and April 2015, all children with a temperature of ≥38°C admitted to a district hospital in Ghana were screened for influenza A and B by RT-PCR and differentiated to subtypes A(H1N1)pdm09 and A(H3N2). Malaria microscopy and blood cultures were performed for each patient.

RESULTS

A total of 1063 children with a median age of 2 years (IQR: 1-4 years) were recruited. Of those, 271 (21%) were classified as severe acute respiratory infection (SARI) and 47 (4%) were positive for influenza, namely 26 (55%) influenza B, 15 (32%) A(H1N1)pdm09, and 6 (13%) A(H3N2) cases. Influenza predominantly occurred in children aged 3-5 years and was more frequently detected in the major rainy season (OR = 2.9; 95% CI: 1.47-6.19) during the first half of the year. Two (4%) and seven (15%) influenza-positive children were co-diagnosed with an invasive bloodstream infection or malaria, respectively.

CONCLUSION

Influenza contributes substantially to the burden of hospitalized febrile children in Ghana being strongly dependent on age and corresponds with the major rainy season during the first half-year.

Sentinel surveillance for influenza among severe acute respiratory infection and acute febrile illness inpatients at three hospitals in Ghana

Background

Influenza epidemiology in Africa is generally not well understood. Using syndrome definitions to screen patients for laboratory confirmation of infection is an established means to effectively conduct influenza surveillance.

Methods

To compare influenza‐related epidemiologic data, from October 2010 through March 2013, we enrolled hospitalized severe acute respiratory infection (SARI; fever with respiratory symptoms) and acute febrile illness (AFI; fever without respiratory or other localizing symptoms) patients from three referral hospitals in Ghana. Demographic and epidemiologic data were obtained from enrolled patients after which nasopharyngeal and oropharyngeal swabs were collected, and processed by molecular methods for the presence of influenza viruses.

Results

Of 730 SARI patients, 59 (8%) were influenza positive; of 543 AFI patients, 34 (6%) were positive for influenza. Both SARI and AFI surveillance yielded influenza A(H3N2) (3% versus 1%), A(H1N1)pdm09 (2% versus 1%), and influenza B (3% versus 4%) in similar proportions. Data from both syndromes show year‐round influenza transmission but with increased caseloads associated with the rainy seasons.

Conclusions

As an appreciable percentage of influenza cases (37%) presented without defined respiratory symptoms, and thus met the AFI but not the SARI definition, it is important to consider broader screening criteria (i.e., AFI) to identify all laboratory‐confirmed influenza. The identified influenza transmission seasonality has important implications for the timing of related public health interventions.