Strategy for diagnosis of congenital toxoplasmosis: evaluation of methods comparing mothers and newborns and standard methods for postnatal detection of immunoglobulin G, M, and A antibodies.

In a study involving 14 laboratories supported by the European Community Biomed 2 program, we evaluated immunologic methods for the postnatal diagnosis of congenital toxoplasmosis (CT). Among babies born to mothers who seroconverted to positivity for toxoplasmosis during pregnancy, we analyzed 55 babies with CT on the basis of persistent anti-Toxoplasma immunoglobulin G (IgG) at 1 year of life and 50 control babies without anti-Toxoplasma IgG at 1 year of life in the absence of curative treatment with pyrimethamine-sulfonamides. We tested in-house methods such as the enzyme-linked immunofiltration assay (ELIFA) or Immunoblotting (IB) for the detection of IgG or IgM; these methods allowed comparison of the immunologic profiles of the mothers and the infants. We compared ELIFA and IB with a commercial enzyme immunoassay (EIA) or in-house immunosorbent agglutination assay (ISAGA) for the detection of IgM or IgA. The performances of combinations of methods were also assessed. A cumulative sensitivity of 98% during a 1-year follow-up was obtained with the ELIFA plus ISAGA combination. Only one case of CT was missed by the ELIFA plus ISAGA combination, whereas three cases were missed by the IB plus ISAGA combination, even though 48% of patients with CT were treated with pyrimethamine-sulfonamides, which are known to inhibit antibody neosynthesis. A similar performance was obtained with either ELIFA or IB in combination with EIA. The difference in performance between ELIFA plus ISAGA and IB plus ISAGA was not statistically significant (P = 0.31), and we conclude that both combinations of tests can be used for the diagnosis of CT in newborns.

A study of postoperative fever following paediatric tonsillectomy.

The aetiology of post-tonsillectomy fever is obscure. Bacteraemia during surgery, anaesthetic agents and the inflammatory response of tissue to injury have been implicated. A prospective study was undertaken in 100 consecutive children to evaluate the occurrence and severity of fever in the 24 h after tonsillectomy and its relationship to bacteraemia during surgery and qualitative and quantitative cultures (colony counts) of organisms in tonsil core tissue. Fifty-four patients had a fever (> 37.5 degrees C) postoperatively, of whom, 30 had a fever greater than 38 degrees C. Blood cultures during tonsillectomy were positive in 22 patients. There was no statistically significant difference between the occurrence of fever and the techniques of tonsillectomy and haemostasis. There was also no association between positive blood, core or surface cultures and the incidence or severity of fever nor any association between colony count in core cultures and fever. Our results suggest that postoperative fever in the 24 h following tonsillectomy is not caused by infection.

A community outbreak of invasive and non-invasive group A beta-haemolytic streptococcal disease in a town in South Wales.

An increase in the incidence of invasive and non-invasive infections caused by group A beta-haemolytic streptococci (GAS) was noted in and around the town of Glynneath (population approx. 4000) in West Glamorgan, South Wales between 1 January and 30 June 1995. A total of 133 cases was ascertained with 127 (96%) occurring between 1 March and 30 June 1995. Six patients had invasive disease (one died) and all presented at the peak of the outbreak. There were 127 non-invasive cases of whom 7 were hospitalized. The outbreak was investigated to determine its extent and whether it was caused by a single M-serotype of GAS. Serotyping showed that 13 different M-serotypes were involved with the M1 serotype predominating. The overall incidence of GAS invasive disease in West Glamorgan (population 365,000) increased sevenfold from a crude incidence of 0.5/10(5) per year in 1994 to 3.5/10(5) per year in 1995, but fell back to 0.75/10(5) per year in 1996. Eighty-two (80%) out of 102 individuals affected by GAS replied to a health questionnaire; sore throat was the commonest symptom reported (97%). Thirty-nine of these index cases identified at least one other member of their household who had experienced similar symptoms. The interval between the onset of illness in members of a single household was 0-83 days with a mean of 22 days. The mean duration of illness was 13.5 days and 61% of patients were treated with penicillin V for a mean duration of 9.3 days. Twenty-one per cent of GAS isolates were erythromycin-resistant and the M4 and M6 serotypes were especially resistant to erythromycin (87.5 and 100% resistance, respectively). Penicillin V failed to eradicate GAS from the throats of 25% of assessable patients. In this community, an outbreak of non-invasive disease caused by GAS was linked in time and place with an outbreak of serious invasive disease.

Detection of the agent of human granulocytic ehrlichiosis (HGE) in UK ticks using polymerase chain reaction.

Nymphal Ixodes ricinus ticks collected from woodland areas in South Wales, UK, were tested using the polymerase chain reaction for the presence both of the causative agent of human granulocytic ehrlichiosis (HGE) and Borrelia burgdorferi. Twenty-two of 60 (37%) ticks were found positive in the PCR for B. burgdorferi and 4/60 (7%) for the HGE agent. One tick was found positive both for B. burgdorferi and HGE agent. Our findings imply the presence of the HGE agent in UK ticks and the finding of a tick apparently containing both pathogens underlines the potential for concurrent infection with HGE agent and B. burgdorferi to occur after a single tick-bite. Based on our observations, we conclude that there may be a need to consider a range of pathogens both in laboratory investigation and clinical management of suspected tick-borne disease in the UK, particularly where there is a clinical presentation atypical of Lyme borreliosis alone.

The prevalence of toxoplasma antibodies in pregnant Nigerian women and the occurrence of stillbirth and congenital malformation.

Toxoplasma antibody serological tests were carried out using the Dye test on sera of pregnant and postpartum Nigerian women to investigate whether there was any association between the levels of antibody titres and the occurrence of stillbirths and congenital malformations. There was a high prevalence of toxoplasma antibodies in the sera of both pregnant and postpartum women. The prevalence rates for the pregnant women ranged from 72.5% to 88.8% with an overall rate of 75.4%; whilst for the postpartum women, the prevalence rates ranged from 75.0% to 94.4% with an overall rate of 80.5%. The toxoplasma antibody titres of the sera from the live-born babies as well as stillbirths and congenitally malformed babies ranged from 1:16 to 1:1024. The exact role played by toxoplasma in the occurrence of stillbirths and congenital malformation in our area of study is, however, not clear. For future research, it is suggested that larger samples be studied in order to enhance the validity of the findings of the present study.

Classification system and case definitions of Toxoplasma gondii infection in immunocompetent pregnant women and their congenitally infected offspring. European Research Network on Congenital Toxoplasmosis.

Classification systems and case definitions provide the foundations upon which clinical and epidemiological studies are based. The European Research Network on Congenital Toxoplasmosis acknowledged the lack of such a system or definitions within its field of interest and established a working group to address the issue. Congenital Toxoplasma gondii infection was defined as occurring in four separate patient groups: pregnant women, fetuses, infants, and individuals > 1 year of age. The likelihood of Toxoplasma gondii infection was separated into five mutually exclusive categories: definite, probable, possible, unlikely, and not infected. Inclusion within a specific category is dependent upon the case definition, which is in turn derived from criteria based on serological, parasitological, and clinical information. Notes are included within the classification not only to clarify the definitions, but also to improve the reliability and quality of diagnosis. The goal is to construct a system that encompasses all aspects of congenital toxoplasmosis, which is applicable to different countries and health services, suitable for large epidemiological studies, aids the diagnosis and management of individual cases, and lends itself to computerisation.

Potential of the polymerase chain reaction in the diagnosis of active Toxoplasma infection by detection of parasite in blood.

Blood samples from 54 patients presenting with acute toxoplasmic lymphadenopathy were tested for the presence of Toxoplasma gondii DNA using a nested polymerase chain reaction (PCR). PCR test results of a single blood sample obtained 2-23 weeks after onset of illness were positive for 19 (35%) of the 54 patients. Nine (53%) of 17 patients were positive by PCR when the initial blood sample was collected within the first 5 weeks of illness. In 7 of the 19 patients found positive, further blood samples were available, and subsequent clearance of T. gondii DNA from the blood was demonstrated. On the basis of positive findings among patients with acute toxoplasmosis and the absence of positive findings among 10 uninfected persons and 43 with past Toxoplasma infection, a positive PCR result appears to be a helpful indicator of active disease. However, since only 53% of patients with lymphadenopathy persisting < or = 5 weeks were positive, a negative PCR result does not exclude recent infection.

Toxoplasmosis in England and Wales 1981 to 1992.

We have examined laboratory reports of toxoplasmosis received by the PHLS Communicable Disease Surveillance Centre between January 1981 and December 1992 in order to describe epidemiological trends in the three main clinical manifestations of toxoplasmosis-lymphadenopathy, eye disease, and neurological disease; and the two most important risk groups-fetuses and people whose immunity is impaired. The total numbers of reports each year did not change significantly between 1981 and 1992 and were similar to the numbers between 1976 and 1980, but different trends emerged in each subgroup. Reports of acute lymphadenopathic toxoplasmosis declined in children and young adults and eye disease associated with toxoplasmosis fell markedly in all age groups. Reports of neurological disease and severe toxoplasmosis complicating impaired immunity, due mainly to HIV infection or transplant surgery, rose. Reports of infections diagnosed in pregnancy rose steeply in the late 1980s although reports of congenital toxoplasmosis were no more common than in 1975 to 1980. Reports of acute toxoplasmosis came mainly from southern England. The emergence of these diverse trends from apparently unchanging totals emphasises the importance of surveillance systems capable of discrimination.

Chronic active toxoplasmosis in an immunocompetent patient.

We report the case of an apparently immunocompetent woman whose symptoms and signs have persisted for 8 years following a serologically and histologically confirmed diagnosis of toxoplasmosis. During this period she had two successful pregnancies despite persistently increased anti-toxoplasma IgM antibodies. Neither child is infected.

Duration of specific immunoglobulin A antibody following acute toxoplasmosis as determined by enzyme immunoassay and immunosorbent agglutination assay.

Modifications of an enzyme immunoassay (EIA) and an immunosorbent agglutination assay (ISAGA) for measuring Toxoplasma gondii-specific IgM antibody were made to enable the measurement of Toxoplasma gondii-specific IgA antibody. It was shown that specific IgA could be measured by both assays but that the ISAGA was slightly more sensitive. IgA appears about two weeks after IgM and persists for 6 to 7 months. However, the IgA response varies considerably both in degree and duration, and demonstration of IgM antibody is at present the most suitable routine test for the diagnosis of recent Toxoplasma gondii infection.

The prevalence of Toxoplasma infection among pregnant women in Ibadan, Nigeria.

The seroprevalence of toxoplasmosis in pregnant women from the inner area of Ibadan was determined by the dye test. Two hundred and seventy-three of the 352 women (78%) had dye test titres of 1/16 or greater with 165 (47%) having titres of 1/128 or greater. In contrast, 42 of 192 pregnant women (22%) from the Swansea area of the UK were dye test positive with only six (3%) having titres of 1/128. The possibility that reinfection or recrudescence is responsible for maintaining high antibody levels in African women and the consequence of this high level of infection in relation to potential human immune deficiency virus (HIV) infections are discussed. Social and environmental conditions indicate that the source of infection is contact with cat faeces.

PIP: A health practitioner took blood samples from 352 pregnant women who attended the antenatal clinic at either the University College Teaching Hospital or St. May's Catholic Hospital in Ibadan City, Nigeria to determine the prevalence of toxoplasma infection among these women. The practitioner also took 241 samples from both women and newborns just after delivery. The samples were flown to the Toxoplasma Reference Unit of the Public Health Laboratory in Swansea, Wales to be tested by the toxoplasma dye test (DT) and ELISA IgM method. The DTs showed that 78% of the Nigerian women had titres of =or1/16. Further 47% had titres of =or1/128. On the other hand, these corresponding figures for pregnant women in Swansea, Wales were only 22% and 3%. Yet only 1 DT titre positive sample among those from the Nigerian women tested positive using the ELISA IgM method. The infant of the women who had a detectable toxoplasma specific IgM exhibited polydactylism, a common congenital abnormality in Ibadan. The researchers suggested that reinfections or recrudescence may account for the high antibody levels. The inner area of Ibadan, where 98% of these pregnant women lived, was overcrowded with poor environmental sanitation conditions including considerable contamination of cat feces. This situation most likely explains the higher prevalence of toxoplasma infection among pregnant women in Ibadan than among those in Swansea, Wales. This high rate of chronic toxoplasmosis poses a considerable potential risk as HIV spreads in Africa since cerebral toxoplasmosis is an opportunistic infection of AIDS.

Epidemiology of toxoplasmosis in the U.K.

The overall rate of toxoplasma infection in the U.K. is between 23-33% though there is evidence of regional variation. Seropositivity increases by 0.5-1.0% per annum to reach about 50% at the age of 60 years. The incidence of acute infection in pregnant women is about 2-2.6% per thousand pregnancies while the transplacental transmission rate is reported to range from 0% to 40%. As there is no official notification of congenital toxoplasma infections within U.K. the true number of cases is not known. However, information relating to the prevalence of infection in the general population in the U.K. is outdated and new studies are urgently required.

Potential role of IgG avidity for diagnosing toxoplasmosis.

Sera from 20 cases of toxoplasmic lymphadenopathy were examined by an enzyme linked immunosorbent assay toxoplasma IgG avidity (ELISA) at two laboratories. The results obtained were largely in agreement and showed that sera from patients with acute infection had low avidity IgG (30% or less), whereas sera from patients with chronic infection had high avidity IgG (40% or more). It is suggested that this type of assay could have a useful complementary role in antenatal testing for toxoplasmosis.