The parasite Toxoplasma gondii can cause congenital toxoplasmosis following primary infection in a pregnant woman. It is therefore important to distinguish between recent and past infection when both ...T. gondii-specific IgM and IgG are detected in a single serum in pregnant women. Toxoplasma gondii-specific IgG avidity testing is an essential tool to help to date the infection. However, interpretation of its results can be complex.
To review the benefits and limitations of T. gondii-specific avidity testing in pregnant women, to help practitioners to interpret the results and adapt the patient management.
PubMed search with the keywords avidity, toxoplasmosis and Toxoplasma gondii for articles published from 1989 to 2019.
Toxoplasma gondii-specific IgG avidity testing remains a key tool for dating a T. gondii infection in immunocompetent pregnant women. Several commercial assays are available and display comparable performances. A high avidity result obtained on a first-trimester serum sample is indicative of a past infection, which occurred before pregnancy. To date, a low avidity result must still be considered as non-informative to date the infection, although some authors suggest that very low avidity results are highly suggestive of recent infections depending on the assay. Interpretation of low or grey zone avidity results on a first-trimester serum sample, as well as any avidity result on a second-trimester or third-trimester serum sample, is more complex and requires recourse to expert toxoplasmosis laboratories.
Although used for about 30 years, T. gondii-specific avidity testing has scarcely evolved. The same difficulties in interpretation have persisted over the years. Some authors have proposed additional thresholds to exclude an infection of <9 months, or in contrast to confirm a recent infection. Such thresholds would be of great interest to adapt management of pregnant women and avoid unnecessary treatment; however, they need confirmation and further studies.
A prospective population-based cohort study with a nested case-control study was conducted to estimate the incidence of gastroenteritis and the associated pathogens in the general Dutch population. ...Follow-up of two consecutive cohorts was performed by weekly reporting cards from December 1998 to December 1999. Cases and controls in the case-control study supplied a questionnaire and stool samples. The standardized gastroenteritis incidence was 283 per 1,000 person-years. The incidence rose with increasing level of education and was higher for persons with a history of diarrhea and for young children. Bacterial pathogens accounted for 5% of cases, bacterial toxins for 9%, parasites for 6%, and viral pathogens for 21%, with Norwalk-like virus (NLV) as the leading pathogen in 11% of cases. The gastroenteritis incidence was higher than that reported for England, but lower than for the United States. In community cases, viral pathogens are the leading cause of gastroenteritis, with NLV being the number one cause of illness in all age groups but one. In many countries, preventive measures are implemented to decrease bacterial infections. However, additional prevention of viral infections, especially NLV, might significantly decrease the number of gastroenteritis cases in the community.
This study aimed to (i) determine risk factors for enteropathogen co-infections, (ii) determine whether enteropathogen co-infections influence gastroenteritis risk, and (iii) determine whether ...enteropathogen co-infection occurred randomly in preschool children.
A monthly-repeated cross-sectional survey in Dutch children aged 0–48 months was conducted during October 2012 to October 2014. A total of 981 stool samples were collected along with questionnaires collecting data on gastrointestinal symptoms and potential risk factors; 822 samples were successfully tested for 19 enteropathogens using real-time multiplex PCRs. Logistic regression analysis assessed co-infections in relation to gastroenteritis and potential risk factors.
In all, 598/822 (72.7%) stool samples tested positive for at least one enteropathogen, of which 290 (48.5%) were positive for two or more enteropathogens. Risk factors for two or more enteropathogen co-infections were young age (<12 months, OR 1.9, 95% CI 1.1–3.3; 13–36 months, OR 1.7, 95% CI 1.1–2.5, versus 37–48 months), day-care attendance (OR 1.8, 95% CI 1.3–2.5), households with three or more children versus those with one child (OR 1.7, 95% CI 1.1–2.8). Stool samples collected in spring less often had two or more enteropathogens versus summer (OR 0.4, 95% CI 0.2–0.7). Food allergy was a risk factor for three or more enteropathogen co-infections (OR 3.2, 95% CI 1.1–8.9). The frequency of co-infection was higher than expected for norovirus GI/norovirus GII, Clostridium difficile/norovirus GI, C. difficile/rotavirus, astrovirus/Dientamoeba fragilis, atypical enteropathogenic Escherichia coli/adenovirus, typical enteropathogenic E. coli/adenovirus, and enteroaggregative E. coli/astrovirus. No co-infection was associated with increased gastroenteritis risk.
Risk factors for enteropathogen co-infections were identified and specific enteropathogens co-occurred significantly more often than expected by chance. Enteropathogen co-infections were not associated with increased gastroenteritis risk, calling into question their clinical relevance in preschool children.
Giardia duodenalis (syn.
Giardia lamblia,
Giardia intestinalis) is a protozoan organism that can infect the intestinal tract of many animal species including mammals. Genetic heterogeneity of
G. ...duodenalis is well described but the zoonotic potential is still not clear. In this study, we analysed 100
Giardia DNA samples directly isolated from human stool specimens, to get more insight in the different
G. duodenalis assemblages present in the Dutch human population. Results showed that these human isolates could be divided into two main Assemblages A and B within the
G. duodenalis group on the basis of PCR assays specific for the Assemblages A and B and the DNA sequences of 18S ribosomal RNA and the glutamate dehydrogenase (
gdh) genes. Genotyping results showed that
G. duodenalis isolates originating from Dutch human patients belonged in 35% of the cases to Assemblage A (34/98) and in 65% of the cases to Assemblage B (64/98) whereas two human cases remained negative in all assays tested. In addition, we compared these human samples with animal samples from the Netherlands and human and animal samples from other countries. A phylogenetic analysis was carried out on the DNA sequences obtained from these
Giardia and those available in GenBank. Using
gdh DNA sequence analysis, human and animal Assemblage A and B
Giardia isolates could be identified. However, phylogenetic analysis revealed different sub-clustering for human and animal isolates where host–species-specific assemblages (C, D, E, F and G) could be identified. The geographic origin of the human and animal samples was not a discriminating factor.
Disease Burden of Congenital Toxoplasmosis Havelaar, A. H.; Kemmeren, J. M.; Kortbeek, L. M.
Clinical infectious diseases,
06/2007, Letnik:
44, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Although the outcomes of toxoplasmosis have been well documented, an integrated estimate of the impact of this infection on the health status of the population is not available. "Disability-adjusted ...life years" are the sum of years of life lost and years lived with disability, weighted for the severity of the illness. The estimated disease burden of congenital toxoplasmosis in The Netherlands is 620 (range, 220-1900) disability-adjusted life years per year, which is similar to that for salmonellosis and is mainly caused by fetal loss and chorioretinitis. However, there is considerable uncertainty in this estimate. Scenario analysis indicates that the true burden may be underestimated. In other countries, the disease burden is expected to vary with the incidence of congenital infection, but it may also depend on the health care system. In countries that actively screen for toxoplasmosis, such as France, there may be a lower burden of morbidity but a higher burden of mortality.
Toxocara canis, Toxocara cati
and
Ascaris suum
are roundworms of dogs, cats and pigs, respectively, that can also infect humans. These zoonotic helminths have a worldwide distribution and are also ...endemic in the Netherlands. Infection with
Toxocara sp.
may result in visceral larva migrans (VLM) or ocular larva migrans (OLM) caused by the migrating larvae. Although
A. suum
has been reported to occasionally mature to the adult stage in humans, clinical cases of VLM suspected to be caused by
A. suum
have been described. Diagnosis of these helminth infections relies mainly on serology. Here we analyse the results from the
Toxocara
and
Ascaris
IgG-ELISA from a total of 2,838 serum samples from VLM and OLM suspected patients that were sent to our institution from 1998 to 2009. Results indicate that for each year the
Ascaris
seropositivity is significantly higher compared to the
Toxocara
seropositivity. Furthermore, while
Toxocara
seropositivity has decreased over time, the
Ascaris
seropositivity has not significantly changed for the past 12 years. The
Ascaris
and
Toxocara
seropositivity was also shown to increases with age and, while gender has no influence on the
Ascaris
seropositivity, males showed higher
Toxocara
seropositivity.
The calculation of disability-adjusted life years (DALYs) enables
public health policy makers to compare the burden of disease of a
specific disease with that of other (infectious) diseases. The
...incidence of a disease is important for the calculation of DALYs. To
estimate the incidence of congenital toxoplasmosis (CT), a random
sample of 10,008 dried blood spot filter paper cards from babies born
in 2006 in the Netherlands were tested for Toxoplasma gondii-specific
IgM antibodies. Eighteen samples were confirmed as positive for IgM,
resulting in an observed birth incidence of CT of 1.8 cases per 1,000
live-born children in 2006 and an adjusted incidence of 2.0 cases per
1,000. This means that 388 infected children were born in 2006. The
most likely burden of disease is estimated to be 2,300 DALYs (range
820-6,710 DALYs). In the previous calculations, using data from a
regional study from 1987, this estimate was 620 DALYs (range 220-1,900
DALYs). The incidence of CT in the Netherlands is much higher than
previously reported; it is 10 times higher than in Denmark and 20 times
higher than in Ireland, based on estimates obtained using the same
methods. There is no screening program in the Netherlands; most
children will be born asymptomatic and therefore will not be detected
or treated.
To estimate the change in the seroprevalence and risk factors for toxoplasmosis in The Netherlands, a study was conducted in the general population in 2006/2007, similarly designed as a previous ...study in 1995/1996. Testing 5541 sera for IgG antibodies against Toxoplasma gondii showed a marked decrease of the overall seroprevalence to 26·0% 95% confidence interval (CI) 24·0–28·0, compared to 40·5% (95% CI 37·5–43·4) in 1995/1996. In women of reproductive age the seroprevalence decreased from 35·2% (95% CI 32·9–38·6) in 1995/1996 to 18·5% (95% CI 16·2–20·7) in 2006/2007, leaving the majority of pregnant women susceptible to primary infection with T. gondii and their babies to congenital toxoplasmosis. In participants aged ≥20 years, Toxoplasma seropositivity was associated with living in the Northwest, living in urban areas, low educational level, consumption of raw pork, keeping a cat, and not having occupational contact with clients or patients. For younger participants, risk factors were keeping sheep or cattle, consumption of raw unwashed vegetables and putting sand in the mouth.
Data from a general practice-based, case-control study on gastroenteritis and the pathogens related to this disease were used to study the association between specific pathogens and the infected ...patients' ages and symptoms. For comparison, the occurrence of these pathogens in control patients, stratified by age, also is presented. In children with gastroenteritis who were <5 years of age, rotavirus (in 21% of patients) and Norwalk-like virus (NLV; in 15%) were the most common pathogens. Among patients who were 5-14 years of age, Campylobacter species (in 16% of patients) and Giardia lamblia (in 10%) were the most common pathogens. In the older patients, Campylobacter species was also the most common pathogen (8% to 15% of patients). In addition, several symptoms in case patients were associated with specific pathogens. Blood in the stool was associated with infection with Campylobacter species. In patients with fever, Salmonella species, Campylobacter species, and rotavirus were detected relatively often. Vomiting was associated with NLV and rotavirus. This is the first study in The Netherlands and one of the first studies in the world that has investigated a broad range of pathogens recovered from an unselected population of patients who had consulted general practitioners because of gastroenteritis.
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