Malaria is endemic in Guinea; however, the extent and role in transmission of asymptomatic malaria are not well understood. In May 2023, we conducted a rapid community survey to determine Plasmodium falciparum (P. falciparum) prevalence among asymptomatic individuals in Middle Guinea (Prefecture Dalaba) and Forest Guinea (Prefecture Guéckédou). In Dalaba, 6 of 239 (2.1%, confidence interval (CI) 0.9–4.8%) individuals tested positive for P. falciparum by a rapid diagnostic test (RDT), while in Guéckédou, 147 of 235 (60.9%, CI 54.5–66.9%) participants tested positive. Asymptomatic malaria needs to be considered more strongly as a driver of transmission when designing control strategies, especially in Forest Guinea and potentially other hyper-endemic settings.

We studied severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence among pregnant women in Norway by including all women who were first trimester pregnant (n = 6520), each month from December 2019 through December 2020, in the catchment region of Norway's second-largest hospital. We used sera that had been frozen stored after compulsory testing for syphilis antibodies in antenatal care. The sera were analysed with the Elecsys® Anti-SARS-CoV-2 immunoassay (Roche Diagnostics, Cobas e801). This immunoassay detects IgG/IgM against SARS-CoV-2 nucleocapsid antigen. Sera with equivocal or positive test results were retested with the Liaison® SARS-CoV-2 S1/S2 IgG (DiaSorin), which detects IgG against the spike (S)1 and S2 protein on the SARS-CoV-2 virus. In total, 98 women (adjusted prevalence 1.7%) had SARS CoV-2 antibodies. The adjusted seroprevalence increased from 0.3% (1/445) in December 2019 to 5.7% (21/418) in December 2020. Out of the 98 seropositive women, 36 (36.7%) had serological signs of current SARS-CoV-2 infection at the time of serum sampling, and the incidence remained low during the study period. This study suggests that SARS CoV-2 was present in the first half of December 2019, 6 weeks before the first case was recognised in Norway. The low occurrence of SARS-CoV-2 infection during 2020, may be explained by high compliance to extensive preventive measures implemented early in the epidemic.

The prevalence of many diseases in pigs displays seasonal distributions. Despite growing concerns about the impacts of climate change, we do not yet have a good understanding of the role that weather factors play in explaining such seasonal patterns. In this study, national and county-level aggregated abattoir inspection data were assessed for England and Wales during 2010–2015. Seasonally-adjusted relationships were characterised between weekly ambient maximum temperature and the prevalence of both respiratory conditions and tail biting detected at slaughter. The prevalence of respiratory conditions showed cyclical annual patterns with peaks in the summer months and troughs in the winter months each year. However, there were no obvious associations with either high or low temperatures. The prevalence of tail biting generally increased as temperatures decreased, but associations were not supported by statistical evidence: across all counties there was a relative risk of 1.028 (95% CI 0.776–1.363) for every 1 °C fall in temperature. Whilst the seasonal patterns observed in this study are similar to those reported in previous studies, the lack of statistical evidence for an explicit association with ambient temperature may possibly be explained by the lack of information on date of disease onset. There is also the possibility that other time-varying factors not investigated here may be driving some of the seasonal patterns.

The status of rabies as a neglected disease has made its eradication rather challenging in different parts of the world despite the availability of a successful vaccine. Lebanon, in particular, is a country endemic to the disease with several cases of rabies deaths reported over the past 30 years. The risk of rabies, however, has taken a new turn over the past few years in Lebanon with two emerging situations that have made the control of the disease rather challenging: the neighbouring Syrian war and the local garbage crisis. Both of these milestone events might have contributed to an increase in the number of disease vectors as well as individuals at risk, thus nourishing the cycle of disease transmission. In this observational study, the effect of these two events are investigated, with an update on the status of this preventable, yet often neglected, disease in the country. Both events were found to be concomitant with a notable increase in the number of dog bites and thus possible rabies exposure. Current regulations are explored through interviews with veterinarians, and custom recommendations, ranging from policies to control dog populations to awareness campaigns in high-risk individuals, are then proposed to help control the disease.

Following an extensive contact tracing exercise at a school in a London borough with one of highest tuberculosis (TB) rates in England, we estimated the background prevalence of latent TB infection to be significantly less than the widely accepted 10%. We screened 271 pupils aged 14–15 years in two groups: 96 pupils in group 1 had significant exposure (>8 h/week in the same room) to a case of infectious TB and 175 in group 2 who had minimal exposure. In group 1, 26% were diagnosed with latent or active TB, compared to 6.3% in group 2. Risk factors for TB infection (e.g. previous exposure or link to high-prevalence communities) were analysed using a cohort study design. In the univariable analysis only being in contact group 1 was statistically significantly associated with being a case (OR 5.25, 95%, P < 0.001). In the multivariable model contact group 1 remained significantly associated with being a case (adjusted OR 4.40, P = 0.001). We concluded that the 6.3% yield of TB infection in contact group 2 is either similar to or higher than the background prevalence rate of latent TB infection (LTBI) in this high TB prevalence London borough. Other parts of England with lower TB prevalence are likely to have even lower LTBI rates.

Chronic hepatitis C virus (HCV) infection is the most common blood-borne infection in the USA. Estimating prevalence is critical for monitoring diagnosis, treatment, and cure and for allocating resources. Surveillance data reported to the New York City (NYC) Health Department, 2000–2015, were used to estimate HCV prevalence in NYC in 2015. The numbers who died, out-migrated or whose last RNA test was negative were removed from the count of people reported with HCV. A simulation model was used to remove estimates of people whose infection spontaneously cleared or was cured and to add an estimate of people unaware of infection. The surveillance-based HCV prevalence in NYC in 2015 overall was 1.4% (95% certainty level (CL) 1.2–1.6%; n ≈ 116 000, 95% CL ≈99 000–135 000) and among adults aged ⩾20 years was 1.8% (95% CL 1.5–2.0%, n ≈ 115 000, 95% CL ≈99 000–134 000), lower than the 2010 estimate among adults aged ⩾20 years of 2.4% (n ≈ 147 000). Contributors to the decrease in HCV prevalence from 2010 to 2015 include both the availability of highly effective treatment and also deaths among an ageing population. The 2015 estimate can be used to set NYC-specific HCV screening and treatment targets and monitor progress towards HCV elimination.

Community-led total sanitation (CLTS) is an intervention that strives to end the practice of open defaecation. This study measured the effectiveness of CLTS in Nyando District by examining the association between community open defaecation-free (ODF) status and childhood diarrhoeal illness. A cross-sectional study design was used among households with children ⩽5 years old to ascertain information on acute diarrhoea in the past year (outcome), sanitation and health behaviours. Water testing was conducted to determine Escherichia coli and turbidity levels for 55 water sources. Data were obtained from 210 parents or caregivers from an ODF community and 216 parents or caregivers in a non-ODF community. The non-ODF participants reported a non-significant 16% increased risk of diarrhoea compared with the participants from the ODF community. Children's HIV positivity (adjusted prevalence ratio (aPR) = 2.29; 95% CI 2.07–2.53), unsafe child stool disposal (aPR = 1.92; 95% CI 1.74–2.12) and low household income (aPR = 1.93; 95% CI 1.46–2.56) were associated with diarrhoea, in the non-ODF community. The ODF location had a higher percentage of E. coli in the drinking water compared with the non-ODF location (76.7% vs. 60%). Diarrhoeal disease rates in children ⩽5 years old did not differ by whether a latrine intervention was implemented. Water sampling findings suggest water safety may have decreased the effectiveness of the CLTS’ improvement of childhood diarrhoea. Improved water treatment practices, safe stool disposal and education may improve the CLTS intervention in ODF communities and therefore reduced the risk of childhood diarrhoea.

People who use drugs (PWUD) are a key population for hepatitis B virus (HBV) vaccination and screening. We aimed to estimate the seroprevalence of HBs antigen (HBsAg) and self-reported HBV vaccination history in French PWUD attending harm reduction centres using data from the ANRS-Coquelicot multicentre survey conducted in 2011–2013 in 1718 PWUD. Self-fingerprick blood samples were collected on dried blood spots to detect the presence of HBsAg. HBsAg seroprevalence was estimated at 1·4% [95% confidence interval (CI) 0·8–2·5]. It varied between PWUD born in high (7·6%, 95% CI 2·7–19·1), moderate (2·2%, 95% CI 0·8–5·7) and low (0·7%, 95% CI 0·3–1·5) endemic zones. Factors independently associated with HBsAg carriage were being born in a moderate or high endemic zone or reporting precarious housing. Self-reported HBV vaccination history varied from 47·4% in high endemic zones, to 59·3% and 62·6% for moderate and low endemic zones, respectively. Our results suggest that drug use plays a small and substantial role, respectively, in HBsAg carriage in PWUD born in high/moderate and low endemic zones.

In Norway, no published data on seroprevalence of hepatitis E virus (HEV) in humans and swine exists. Serum samples from blood donors, veterinarians, swine farm workers and swine were analysed by ELISA to estimate the seroprevalence of HEV in Norway and to investigate the association between direct contact with swine and HEV seroprevalence in humans. The seroprevalence of HEV IgG antibodies was 30% (24/79) in farm workers, 13% (21/163) in veterinarians, 14% (162/1200) in blood donors and 90% (137/153) in swine. Our results show a high seroprevalence of HEV in humans and swine in Norway. HEV seroprevalence in farm workers and blood donors increased with age, and veterinarians working with swine were twice as likely to be HEV seropositive compared to other veterinarians. High HEV seroprevalence in farm workers and veterinarians working with swine support previous reports suggesting swine as a reservoir for HEV infections in humans in Europe.

This study aimed to estimate the prevalence and risk factors for hepatitis C virus (HCV) infection in Mexican Americans living in South Texas. We tested plasma for the presence of HCV antibody from the Cameron County Hispanic Cohort (CCHC), a randomized, population-based cohort in an economically disadvantaged Mexican American community on the United States/Mexico border with high rates of chronic disease. A weighted prevalence of HCV antibody of 2·3% [n = 1131, 95% confidence interval (CI) 1·2–3·4] was found. Participants with diabetes had low rates of HCV antibody (0·4%, 95% CI 0·0–0·9) and logistic regression revealed a statistically significant negative association between HCV and diabetes (OR 0·20, 95% CI 0·05–0·77) after adjusting for sociodemographic and clinical factors. This conflicts with reported positive associations of diabetes and HCV infection. No classic risk factors were identified, but important differences between genders emerged in analysis. This population-based study of HCV in Mexican Americans suggests that national studies do not adequately describe the epidemiology of HCV in this border community and that unique risk factors may be involved.

This study assessed seroprevalence and risk factors for Leptospira (serovars Hardjo, Pomona, Ballum, Copenhageni, Tarassovi) exposure in New Zealand veterinarians. Veterinarians (n = 277) at one of two conferences were voluntarily enrolled and blood samples taken. Microscopic agglutination test (MAT) titres ⩾48 were considered seropositive. Fourteen veterinarians (5·1%, 95% confidence interval 2·8−8·3) were seropositive to Leptospira. Home slaughter of cattle or pigs were significant risk factors for Leptospira exposure. There were no clear relationships between the animal species handled at work and serostatus. However, veterinarians spending a ‘mid to high’ proportion of their time (>50% to ⩽75%) with pets had higher odds of being seropositive than those not working with pets. A borderline positive association (P = 0·09) was observed between seropositivity and clinical influenza-like illness (⩾3 days off work) in the 18 months before the study. Assuming causality, this suggests that 8·3% of these cases may be attributed to Leptospira exposure.

We aimed to reparameterize and validate an existing dengue model, comprising an entomological component (CIMSiM) and a disease component (DENSiM) for application in Malaysia. With the model we aimed to measure the effect of importation rate on dengue incidence, and to determine the potential impact of moderate climate change (a 1 °C temperature increase) on dengue activity. Dengue models (comprising CIMSiM and DENSiM) were reparameterized for a simulated Malaysian village of 10 000 people, and validated against monthly dengue case data from the district of Petaling Jaya in the state of Selangor. Simulations were also performed for 2008-2012 for variable virus importation rates (ranging from 1 to 25 per week) and dengue incidence determined. Dengue incidence in the period 2010–2012 was modelled, twice, with observed daily weather and with a 1 °C increase, the latter to simulate moderate climate change. Strong concordance between simulated and observed monthly dengue cases was observed (up to r = 0·72). There was a linear relationship between importation and incidence. However, a doubling of dengue importation did not equate to a doubling of dengue activity. The largest individual dengue outbreak was observed with the lowest dengue importation rate. Moderate climate change resulted in an overall decrease in dengue activity over a 3-year period, linked to high human seroprevalence early on in the simulation. Our results suggest that moderate reductions in importation with control programmes may not reduce the frequency of large outbreaks. Moderate increases in temperature do not necessarily lead to greater dengue incidence.

People who inject drugs are vulnerable to infections and injuries at injection sites, but these have rarely been studied in those injecting image- and performance-enhancing drugs (IPEDs). This study examined the factors associated with reported symptoms of injection site infections and injuries in IPED injectors. Of the 366 male IPED injectors surveyed, 42% reported ever having redness, swelling and tenderness (36% in the preceding year), and 6·8% had ever had an abscess or open wound at an injection site. Having these symptoms was associated with a range of factors related to drug use and healthcare utilization. One sixth (17%) of those reporting redness, tenderness and swelling had ever sought treatment, as had the majority (76%) of those reporting an abscess, sore or open wound. Most common sources of advice were emergency clinics and General Practitioners. Interventions are needed to support access to appropriate injecting equipment and provide targeted harm reduction advice.

The highly remote pastoralist communities in Kaokoland, Namibia, have long been presumed to have high gonorrhoea prevalence. To estimate gonorrhoea prevalence and correlates of infection, we conducted a cross-sectional study of 446 adults across 28 rural villages. Gonorrhoea status was determined from urethral and vaginal swabs via qPCR assay. All participants answered a closed-ended interview about demographics, sexual behaviour and symptom history. Sixteen per cent of participants had high-level infections (⩾ID50 dose) and 48% had low-level infections (<ID50 dose). Women had higher prevalence than men of both high- and low-level infections. High-level infections were regionally and seasonally clustered, occurring in young adults in the Ehama region during the winter. Low-level infections were distributed homogenously across demographic characteristics, season, and region. All low-level infections and most high-level infections (men 78%, women 95%) were asymptomatic and left untreated. The epidemic-like nature of high-level gonorrhoea cases suggests that intervention efforts can be focused on seasons of high social activity.

Migrants born in hepatitis B virus (HBV) and hepatitis C virus (HCV) endemic countries are at increased risk of being infected with these viruses. The first symptoms may arise when liver damage has already occurred. The challenge is to identify these infections early, since effective treatment has become available. In 2011 we conducted a screening project in first-generation migrants (FGMs) born in Afghanistan, Iran, Iraq, the former Soviet Republics, and Vietnam and living in Arnhem and Rheden. All participants were offered free blood screening for HBV and HCV. In total 959 participants were tested, with the country of origin known for 927, equating to 28·7% of all registered FGMs from the chosen countries. Nineteen percent (n = 176) had serological signs of past or chronic HBV infection and 2·2% (n = 21) had chronic HBV infection. The highest prevalence of chronic HBV infection was found in the Vietnamese population (9·5%, n = 12). Chronic HCV was found in two persons from the former Soviet Republics and one from Vietnam. Twenty-four percent (n = 5) of the newly identified patients with chronic HBV and one of the three patients with chronic HCV received treatment. Three of the patients, two with HCV and one with HBV, already had liver cirrhosis. The highest (9·5%) HBV prevalence was found in FGMs from Vietnam, indicating a high need for focusing on that particular immigrant population in order to identify more people with silent HBV infection. The fact that three patients already had liver cirrhosis underlines the necessity of early identification of HBV and HCV infection in risk groups.

To assess the prevalence and risk factors for colonization with Staphylococcus aureus in inmates entering two maximum-security prisons in New York State, USA, inmates (N = 830) were interviewed and anterior nares and oropharyngeal samples collected. Isolates were characterized using spa typing. Overall, 50·5% of women and 58·3% of men were colonized with S. aureus and 10·6% of women and 5·9% of men were colonized with MRSA at either or both body sites. Of MSSA isolates, the major subtypes were spa type 008 and 002. Overall, risk factors for S. aureus colonization varied by gender and were only found in women and included younger age, fair/poor self-reported general health, and longer length of prior incarceration. Prevalence of MRSA colonization was 8·2%, nearly 10 times greater than in the general population. Control of epidemic S. aureus in prisons should consider the constant introduction of strains by new inmates.

Hepatitis C virus is the most common chronic blood-borne infection in the USA. Based on results of a serosurvey, national prevalence is estimated to be 1·3% or 3·2 million people. Sub-national estimates are not available for most jurisdictions. Hepatitis C surveillance data was adjusted for death, out-migration, under-diagnosis, and undetectable blood RNA, to estimate prevalence in New York City (NYC). The prevalence of hepatitis C infection in adults aged ⩾20 years in NYC is 2·37% (range 1·53–4·90%) or 146 500 cases of hepatitis C. This analysis presents a mechanism for generating prevalence estimates using local surveillance data accounting for biases and difficulty in accessing hard to reach populations. As the cohort of patients with hepatitis C age and require additional medical care, local public health officials will need a method to generate prevalence estimates to allocate resources. This approach can serve as a guideline for generating local estimates using surveillance data that is less resource prohibitive.

Animal losses due to abortion and malformed offspring during the lambing period 2011/2012 amounted to 50% in ruminants in Europe. A new arthropod-borne virus, called Schmallenberg virus (SBV), was identified as the cause of these losses. Blood samples were obtained from 40 goat flocks and tested for antibodies against SBV by ELISA, with 95% being seropositive. The calculated intra-herd seroprevalence (median 36·7%, min-max 0–93·3%) was smaller than in cattle or sheep flocks. Only 25% of the farmers reported malformations in kids. Statistical analysis revealed a significantly lower risk of goats housed indoors all year-round to be infected by SBV than for goats kept outside day and night. The low intra-herd seroprevalence demonstrates that German goat flocks are still at risk of SBV infection. Therefore, they must be protected during the next lambing seasons by rescheduling the mating period, implementing indoor housing, and continuous treatment with repellents or vaccination.

Population-based estimates of incidence and risk factors for acute gastrointestinal illness (AGI) are important for infectious disease surveillance and healthcare planning. We conducted a nationwide representative cross-sectional telephone survey of 21 262 adults over a 12-month period during 2008–2009 in Germany. Participants were asked if they had either AGI-related diarrhoea or vomiting in a 4-week recall period. We estimated 0·95 episodes/person per year (95% confidence interval 0·90–0·99), corresponding to 64·9 million episodes of AGI annually in adults, which results in 24·5 million outpatient visits, 19·9 million hospital days and 63·2 million days of work lost. We observed an overall declining trend of AGI with increasing age. Diarrhoea was more often reported than vomiting. The mean duration of illness was 3·8 days and did not differ between age groups. Social factors seemed to be weak predictors compared to state of health and health behaviour characteristics. This study allows international comparisons and contributes to the estimation of the global burden of AGI.

We undertook a national paediatric seroprevalence survey of measles, mumps and rubella (MMR) in Singapore to assess the impact of the national childhood immunization programme against these three diseases after introduction of the trivalent MMR vaccine in 1990. The survey involved 1200 residual sera of Singapore residents aged 1–17 years collected from two hospitals between 2008 and 2010. The overall prevalence of antibodies against measles, mumps and rubella was 83·1% [95% confidence interval (CI) 80·9–85·1], 71·8% (95% CI 69·1–74·2) and 88·5% (95% CI 86·6–90·2), respectively. For all three diseases, the lowest prevalence was in children aged 1 year (47·8–62·3%). The seroprevalence of the vaccinated children declined over time. The national MMR immunization programme is effective in raising the herd immunity of the childhood population, although certain age groups are more susceptible to infection, in particular, those who are not eligible for vaccination at age <15 months.