Background: Human psittacosis, caused by Chlamydia (C.) psittaci, is likely underdiagnosed and underreported, since tests for C. psittaci are often not included in routine microbiological diagnostics. Source tracing traditionally focuses on psittacine pet birds, but recently other animal species have been gaining more attention as possible sources for human psittacosis. This review aims to provide an overview of all suspected animal sources of human psittacosis cases reported in the international literature. In addition, for each animal species the strength of evidence for zoonotic transmission was estimated. Methods: A systematic literature search was conducted using four databases (Pubmed, Embase, Scopus and Proquest). Articles were included when there was mention of at least one human case of psittacosis and a possible animal source. Investigators independently extracted data from the included articles and estimated strength of evidence for zoonotic transmission, based on a self-developed scoring system taking into account number of human cases, epidemiological evidence and laboratory test results in human, animals, and the environment. Results: Eighty articles were included, which provided information on 136 different situations of possible zoonotic transmission. The maximum score for zoonotic transmission was highest for turkeys, followed by ducks, owls, and the category 'other poultry'. Articles reporting about zoonotic transmission from unspecified birds, psittaciformes and columbiformes provided a relatively low strength of evidence. A genotypical match between human and animal samples was reported twenty-eight times, including transmission from chickens, turkeys, guinea fowl, peafowl, pigeons, ducks, geese, songbirds, parrot-like birds and owls. Conclusions: Strong evidence exists for zoonotic transmission from turkeys, chickens and ducks, in addition to the more traditionally reported parrot-like animal sources. Based on our scoring system, the evidence was generally stronger for poultry than for parrot-like birds. Psittaciformes should not be disregarded as an important source of human psittacosis, still clinicians and public health officials should include poultry and birds species other than parrots in medical history and source tracing.

Background Indoor environments are considered one of the main settings for transmission of SARS-CoV-2. Households in particular represent a close-contact environment with high probability of transmission between persons of different ages and with different roles in society. Methods Complete households with a laboratory-confirmed SARS-CoV-2 positive case in the Netherlands (March-May 2020) were included. At least three home visits were performed during 4-6 week of follow-up, collecting naso- and oropharyngeal swabs, oral fluid, feces and blood samples for molecular and serological analyses of all household members. Symptoms were recorded from two weeks before the first visit through to the final visit. Infection secondary attack rates (SAR) were estimated with logistic regression. A transmission model was used to assess transmission routes in the household. Results A total of 55 households with 187 household contacts were included. In 17 households no transmission took place, and in 11 households all persons were infected. Estimated infection SARs were high, ranging from 35% (95%CI: 24%-46%) in children to 51% (95%CI: 39%-63%) in adults. Estimated transmission rates in the household were high, with reduced susceptibility of children compared to adolescents and adults (0.67; 95%CI: 0.40-1.1). Conclusion Estimated infection SARs were higher than reported in earlier household studies, presumably owing to our dense sampling protocol. Children were shown to be less susceptible than adults, but the estimated infection SAR in children was still high. Our results reinforce the role of households as one of the main multipliers of SARS-CoV-2 infection in the population.

BackgroundIndoor environments are considered a main setting for transmission of SARS-CoV-2. Households in particular present a close-contact environment with high probability of transmission between persons of different ages and with different roles in society.MethodsComplete households with a laboratory-confirmed SARS-CoV-2 positive case in the Netherlands (March-May 2020) were included. At least three home visits were performed during 4-6 week of follow-up, collecting naso- and oropharyngeal swabs, oral fluid, faeces and blood samples for molecular and serological analyses of all household members. Symptoms were recorded from two weeks before the first visit up to the last visit. Secondary attack rates (SAR) were estimated with logistic regression. A transmission model was used to assess transmission routes in the household.ResultsA total of 55 households with 187 household contacts were included. In 17 households no transmission took place, and in 11 households all persons were infected. Estimated SARs were high, ranging from 35% (95%CI: 24%-46%) in children to 51% (95%CI: 39%-63%) in adults. Estimated transmission rates in the household were high, with reduced susceptibility of children compared to adolescents and adults (0.67; 95%CI: 0.40-1.1).ConclusionEstimated SARs were higher than reported in earlier household studies, presumably owing to a dense sampling protocol. Children were shown to be less susceptible than adults, but the estimated SAR in children was still high. Our results reinforce the role of households as main multiplier of SARS-CoV-2 infection in the population.Key pointsWe analyze data from a SARS-CoV-2 household study and find higher secondary attack rates than reported earlier. We argue that this is due to a dense sampling strategy that includes sampling at multiple time points and of multiple anatomical sites.

The variable-number tandem-repeat (VNTR) typing method is used to study tuberculosis (TB) transmission. Clustering of isolates with identical VNTR patterns is assumed to reflect recent transmission. Hence, clusters are thought to be homogeneous regarding antibiotic resistance. In practice, however, heterogeneous clusters are also identified. This study investigates the prevalence and characteristics of heterogeneous VNTR clusters and assesses whether isolates in these clusters remain clustered when subjected to whole-genome sequencing (WGS). In the period from 2004 to 2016, 9,072 isolates were included. Demographic and epidemiological linkage data were obtained from the Netherlands Tuberculosis Register. VNTR clusters were defined as homogeneous when isolates shared identical resistance profiles or as heterogeneous if both susceptible and (variable) resistant isolates were found. Multivariate logistic regression analysis was performed to identify factors associated with heterogeneous clustering. Isolates from 2016 were subjected to WGS, and a genetic distance of 12 single nucleotide polymorphisms (SNPs) was used as the cutoff for WGS clustering. In total, 4,661/9,072 (51%) isolates were clustered into 985 different VNTR clusters, of which 217 (22%) were heterogeneous. Patient characteristics associated with heterogeneous clustering were non-Dutch ethnicity (odds ratio [OR], 1.46 [95% confidence interval {CI}, 1.22 to 1.75]), asylum seeker (OR, 1.51 [95% CI, 1.24 to 1.85]), extrapulmonary TB (OR, 1.26 [95% CI, 1.09 to 1.46]), previous TB diagnosis (OR, 1.38 [95% CI, 1.04 to 1.82]), and not being a contact of a TB patient (OR, 1.35 [95% CI, 1.08 to 1.69]). With WGS, 34% of heterogeneous and 78% of homogeneous isolates from 2016 remained clustered. Heterogeneous VNTR clusters are common but seem to be explained by a substantial degree of false clustering by VNTR typing compared to WGS.

Background Chronic illnesses can increase the risk of unemployment, but evidence on the specific impact of Q-fever fatigue syndrome (QFS) on work is lacking. Aims The aim of this study was to describe and quantify the impact of QFS on work. Methods Changes in work status from 1 year prior to 4 years after acute Q-fever infection of QFS patients were retrospectively collected with a self-report questionnaire measuring employment status and hours of paid work per week. In addition, information on work ability, job satisfaction and need for recovery after work was collected in 2016. Data were compared to participants from the general population. Results The proportion of employed QFS patients from 1 year prior to 4 years after acute infection decreased from 78 to 41%, while remaining relatively constant in the general population (82 to 78%). Working QFS patients showed a decrease in mean hours of paid work from 35 to 22 h per week, which is significantly steeper compared to the general population (31–28 h per week) (P < 0.001). QFS patients showed a significantly lower work ability (P < 0.001), lower job satisfaction (P = 0.006) and greater need for recovery (P < 0.001) compared to the general population. Conclusions The number of QFS patients with paid work decreased over the years, while patients who continue to work experience lower work ability, job satisfaction and increased need for recovery. Occupational physicians should be aware of the occurrence and severity of the impact of QFS on work, even after many years.