Marianne Forsgren

A 10-Year Follow-Up Study of Tick-Borne Encephalitis in the Stockholm Area and a Review of the Literature: Need for a Vaccination Strategy

143 people treated for tick-borne encephalitis (TBE) were included in a retrospective follow-up study. Sequelae and epidemiological characteristics in 114 individuals were analysed. The case fatality rate and the prevalence of residual paresis were low, 1.4 and 2.7%, respectively. However, 40 (35.7%) individuals were found to have a postencephalitic syndrome after a median follow-up time of 47 months, and a majority (77.5%) of these were classified as moderate to severe. Various mental disorders, balance and co-ordination disorders and headache were the most frequently reported symptoms. Increasing age was correlated to a longer duration of hospital stay, longer convalescence and increased risk of permanent sequelae. Results from a neuropsychiatric questionnaire showed marked differences between the subjects with sequelae compared to controls. 57% had noticed a tick bite before admission, and 48% were aware of at least one person in their environment who previously had contracted TBE. 79% were permanent residents or visited endemic areas often and regularly. In conclusion, we have found that TBE in the Stockholm area has a low case fatality rate, but gives rise to a considerable number of different neurological and mental sequelae, which justifies vaccination of a defined risk population in endemic areas.

Antigen detection in primary HIV infection.

Serial blood samples were obtained from 21 homosexuals who had developed symptomatic primary infection with human immunodeficiency virus (HIV) after a median incubation time of 14 days. During the first two weeks after the onset of illness HIV antigen (p24) was detected in the blood by enzyme linked immunosorbent assay (ELISA). During the second and third weeks after the onset of illness p24 antibody was detected by Western blot assay and antigen concentrations rapidly decreased to undetectable values. Dissociation of antigen-antibody complexes showed complexed antigen during the phase of declining concentrations of free antigen. Neither free nor complexed antigen was detected in any serum samples for several months thereafter, which suggested that failure to detect HIV antigen reflected low or absent synthesis of viral protein rather than masking of antigen by antibodies. Reappearance of HIV antigen with a fall in p24 antibody concentration was observed in a few patients six months or more after the onset of disease. The combined use of antigen and antibody assays made it possible to obtain evidence of infection with HIV in all of the 95 serum samples tested, illustrating the usefulness of these assays for diagnosing infection with HIV in its early stages.

Prevalence of antibodies to herpes simplex virus in pregnant women in Stockholm in 1969, 1983 and 1989: implications for STD epidemiology.

Prevalence of antibody to herpes simplex virus types 1 and 2 was assessed in consecutive serum samples from a total of 3700 women pregnant in 1969, 1983, or 1989 from the same catchment area in Stockholm. There was little change in seroprevalence of antibody to herpes simplex type 1 in the 3 groups, but age-adjusted herpes simplex virus type 2 antibody prevalence was 19, 33, and 33% respectively. Increase in type 2 seropositivity with age was slight and similar in 1969 and 1989, but steep in 1983, indicating a shift in sexual behaviour. However, rising prevalence in women will be mirrored by rising prevalence in their male partners. The increase from 1969 to 1989 will thus partly be due to higher risk of infection per partner, and cannot be taken as direct evidence of increased rate of partner change during this 20-year period.

Prevalence of Tick-borne Encephalitis and Lyme Borreliosis in a Defined Swedish Population

Sera from 346 individuals living on Lisö, an area south of Stockholm, endemic for tick-borne encephalitis (TBE) and Lyme borreliosis, were tested for antibody activity to TBE-virus (TBEV) and Borrelia burgdorferi, using a sonicate antigen, by haemagglutination-inhibition and ELISA, respectively. 10/346 (3%) individuals had a history of previous serologically confirmed TBE with encephalitic symptoms, and 33/346 (10%) had a history of previous erythema chronicum migrans (ECM). Four individuals (1%) had been treated for neuroborreliosis and another 4 (1%) for acrodermatitis chronica atrophicans (ACA). Antibodies to TBEV and B. burgdorferi were detected in 40/346 (12%) and 89/346 (26%) individuals, respectively. The seroprevalence of Lyme borreliosis increased with age, time spent on Lisö, and number of reported tick-bites. For TBE there was a correlation between seropositivity and time spent on Lisö only. In sera from 50 healthy blood-donors, living in a non-endemic area, no antibody activity to TBEV could be detected and only 1/50 (2%) had antibodies to borrelia. In sera from 150 age and sex matched control individuals, living in the city of Stockholm, antibody activity to TBEV and borrelia was found in 8/150 (5%) and 13/150 (9%), respectively.

Detection of Enteroviral RNA by Polymerase Chain Reaction in Cerebrospinal Fluid from Patients with Aseptic Meningitis

An assay based on a 2-step (semi-nested) polymerase chain reaction (PCR) was developed and evaluated for detection of enterovirus-specific RNA in cerebrospinal fluid (CSF) from patients with aseptic meningitis of different etiology. The limit of detectability of enteroviral RNA was equivalent to about 0.25 tissue culture infective doses 50%. In samples, stored at -70 degrees C, analyzed without repeated thawing, enteroviral RNA was demonstrable in 21/22 CSF specimens from which an enterovirus had been isolated. Enteroviral RNA was shown to be degraded during freeze-thawing of the samples. In repeatedly freeze-thawed samples from 134 consecutive patients with aseptic meningitis, a lower sensitivity (34/48 = 0.71) was observed. In the latest phase of the study, comprising 35 consecutive patients, the PCR was performed in CSF stored at -20 degrees C without thawing. In this material, the PCR yielded positive results in 19 patients, whereas enteroviruses were isolated from 6 cases only. In the total clinical material of 169 patients, 67 (40%) were found positive by PCR, whereas an enterovirus was isolated from CSF in 54 (32%) cases. All the 13 isolated enterovirus serotypes found in the study were demonstrable by PCR, indicating that the assay is broad-reacting within the enterovirus group. The specificity appeared to be high, since all of 21 patients with non-enteroviral diagnoses were negative by the PCR test, except 1 with an Epstein-Barr virus infection. As serological evidence of enteroviral etiology was found in this patient, a dual infection seemed probable. This study indicates that enteroviral RNA can be detected in CSF by a 2-step PCR in meningitis caused by enterovirus and that the technique has the potential to become a screening method for routine diagnosis of enteroviral meningitis.

Two-year survey of the incidence of lyme borreliosis and tick-borne encephalitis in a high-risk population in Sweden

A survey was made over a two-year period (September 1987 to August 1989) of a population living in an area endemic for Lyme borreliosis and tick-borne encephalitis in Sweden. For each patient a blood sample was collected and a questionnaire completed annually. All sera were tested for an antibody response toBorrelia burgdorferi in an EIA using sonicated antigen and for an antibody response to the tick-borne encephalitis virus using an EIA and a haemagglutination inhibition test. Antibodies toBorrelia burgdorferi and tick-borne encephalitis virus were detected in 89 (25.7 %) and 40 (11.6 %) respectively of 346 samples collected in August 1987. In the first year of the study 14 of 303 subjects (4.6 %) developed Lyme borreliosis and in the second year 9 of 277 subjects (3.2 %). A significant increase in the antibody titre forBorrelia burgdorferi was seen in 14 of 303 (4.6 %) subjects in the first year and 8 of 277 (2.9 %) subjects in the second year. An earlier episode of Lyme borreliosis or an elevated antibody titre did not seem to protect against reinfection. One case of tick-borne encephalitis was seen each year. Seroconversion for tick-borne encephalitis virus was found in 3 of 258 (1.2 %) subjects in the first year and 5 of 211 (2.4 %) in the second year, excluding subjects who had undergone successful immunisation or had earlier been hospitalised for tick-borne encephalitis. The study thus demonstrated a high yearly incidence of tick-borne infections in a population at risk.

Screening for HIV-1 antibodies in pregnancy: results from the Swedish national programme.

OBJECTIVE--To determine the effectiveness of a national screening programme for HIV infection in pregnant women. DESIGN--Observational study. SUBJECTS--All pregnant women presenting to antenatal or abortion clinics. SETTING--Sweden, September 1987 to December 1991. MAIN OUTCOME MEASURES--Number and characteristics of infected women. RESULTS--By the end of the study period 510,000 tests had been performed and 54 women with HIV infection identified (1.06/10,000). Of the 33 women identified in Stockholm, 14 women (4.4/10,000) had attended abortion clinics and 19 antenatal clinics (1.8/10,000; p < 0.05). Three women had been intravenous drug users, one was infected through a blood transfusion, and 50 were probably infected sexually. Of the 20 women who attended antenatal clinics early enough to allow an abortion, 12 continued with their pregnancies. CONCLUSIONS--Testing of all women, not just those perceived to be at risk, probably contributed to the high uptake of HIV testing. With high uptake such screening provides valuable data on spread of HIV in the heterosexual population and presents opportunity for preventing transmission of HIV to children and partners.

Aspects on the serodiagnosis of enterovirus infections by ELISA

Abstract The serodiagnosis of enterovirus infections with ELISA was approached with antigens of nine serotypes. Antigens were prepared by differential centrifugation and heated at 56°C. Capture assays were used for IgG and IgM and in addition an indirect technique was used for IgG antibody determinations. The antigens were conjugated with peroxidase for use in capture assays. A panel of acute and convalescent sera from 101 patients with culture-confirmed infections with one of echovirus 4, 6, 9, 11, 18, 30, coxsackie A9, B3, 4, 5 or enterovirus 71 was used for evaluation. The best results for indirect IgG were obtained with a combination of echovirus 9, 30 and coxsackie B5 (with a significant rise in 66 patients—65%). The capture IgG was less sensitive. In IgM tests echovirus 6 and coxsackievirus A9 performed best with a positive reaction in 76 patients (75%). A combination of the IgG and IgM assay demonstrated markers for current enterovirus infection in 89 patients. The appearance of enteroviral IgM was usually transient but was found to persist for 12 months in occasional patients. The prevalence of enteroviral IgM in a “normal” adult population was low (3% sera from pregnant women). These types of assays have a potential as easy, rapid tools for enteroviral diagnosis.

Elevated antibody titers to Epstein-Barr virus and low natural killer cell activity in patients with Chediak-Higashi syndrome

Four Venezuelan patients with the autosomal recessive Chediak-Higashi syndrome (CHS) were studied. The results confirm the severe reduction in natural killer (NK) cell activity, as previously described and showed also a decline in the activity of cells involved in antibody-dependent cellular cytotoxicity (ADCC). No defect was found in the production of immunoglobulins and of specific antibodies to measles, varicella, herpes simplex, and cytomegalo viruses. Two of the patients had extremely high antibody titers to the Epstein-Barr virus (EBV) specific viral capsid antigen (VCA), to the restricted (R) component of the EBV-induced early antigen complex, and to the EBV-associated nuclear antigen (EBNA). These two patients had enlarged livers, spleens, and lymph nodes indicative of the lymphoproliferative phase. The other two patients were initially negative for all EBV-associated antibodies but seroconverted subsequently and, in the course of a year, also developed high antibody titers to VCA and R. In one of these patients the primary infection was accompanied by moderate signs of infectious mononucleosis (IM) followed after more than 6 months by persistent hepatosplenomegaly. The other patient also developed signs of a lymphoproliferative syndrome with hepatosplenomegaly and jaundice and died 8 months later. Such high anti-R titers are seen frequently in Burkitts lymphoma, but rarely in other conditions. It is likely that the high antibody titers reflect an increased production of VCA and R due to defective NK and ADCC cell activities so that productively infected B lymphocytes are no longer eliminated before they have synthesized maximal amounts of antigens. The high anti-EBNA titers suggest normal T lymphocyte function. The possibility that the accelerated, lymphoma-like phase of the CHS involves EBV-transformed cells is discussed.

Late Ophthalmologic Manifestations of Neonatal Herpes Simplex Virus Infection

We examined 32 children one to 15 years after virologically verified neonatal herpes simplex virus infection. Sixteen of 17 (94%) neurologically impaired children had ocular abnormalities compared to three of 15 (20%) neurologically healthy children. Disturbed oculomotor control occurred in 14 children (44%), most of whom were among those with severe handicap. Ocular morbidity was present in 13 (40%) of 32 children: one had cataracts, two had corneal scars, seven had optic atrophy, and nine had chorioretinal scars. The clinically silent chorioretinal lesions were manifest as coarse hyperpigmented areas between the equator and ora serrata. One child had suffered from acute fulminant retinitis. Twelve of 13 (93%) severely handicapped children had impaired vision, mainly because of cortical blindness. Less affected children had normal vision unless corneal scars were present. Long-term observation of patients with neonatal herpes infections is essential because ocular manifestations are not rare, and recurrences may be more common than previously reported.