985 episodes of hepatitis representing 98% of all acute hepatitis episodes found in a Swedish city during a 10-year period were analyzed for anti-hepatitis A IgM antibodies and hepatitis B surface antigen. Hepatitis A was diagnosed in 311 episodes (32%), hepatitis B in 494 (50%), simultaneous acute hepatitis A and B in 12 (1.2%), and 168 episodes (17%) were classified as hepatitis non-A, non-B. The majority of the hepatitis A cases were drug addicts (58%), and all were concentrated in 3 outbreaks of 1-2 years duration. 16% of all hepatitis A cases were probably imported. Hepatitis B cases decreased significantly (p less than 0.001) between the first and second half of the study period. 47% were drug addicts. Hepatitis non-A, non-B was also dominated by drug addicts (61%). Approximately 20% of the cases in all 3 types of hepatitis had no identifiable source.
Serological analysis by radioimunoassay of sera from 297 patients hospitalized with acute non-toxic hepatitis was used for classification according to virus etiology. Radioimmunoassays included tests for hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs), antibody to hepatitis A virus (anti-HAV), anti-HAV of IgM class, and antibody against cytomegalovirus (GMV) and Epstein-Barr virus. One patient with a significant rise in anti-CMV antibodies was classified as having CMV hepatitis. Among the 296 remaining patients serological markers indicated hepatitis A in 51 cases (17.2%) and hepatitis B in 208 cases (70.3%). The remaining 37 patients (12.5%) fulfilled criteria for acute non-A, non-B hepatitis. This type of hepatitis had symptoms and signs indistinguishable from those of hepatitis A, except for a slight tendency to milder disease on admission. A considerable proportion of patients with non-A, non-B hepatitis had a history of drug abuse (43.2%) and of recently traveling to endemic hepatitis areas (29.7%). In the remaining 27.1% no particular background was revealed. No case of post-transfusion hepatitis was seen. During the last 6 months of the study a striking change in epidemiology concerning hepatitis A was seen, apparently caused by a steep increase in the incidence of this type of hepatitis among drug addicts. No significant difference in biochemical liver tests was seen in non-a, non-B hepatitis or hepatitis A. In contrast, a marked and statistically significant difference in serum concentrations of IgM was found, with higher values (mean, 7.5 g/1; range, 3.2-13.9 g/1) in hepatitis A than in non-a, non-B hepatitis (mean, 3.3 g/1; range, 0.9-9.4 g/1). This difference may have diagnostic value.
In 1979-1980, a distinct outbreak of hepatitis A occurred among homosexual men in Stockholm, Sweden, city and county area. The epidemic comprised 145 known cases. It began in December 1979 and progressed in waves during the following 10 months, with three distinct peaks separated by about six-week intervals. Actually, the incidence of hepatitis A in the Stockholm area showed a fivefold increase during 1980 as compared to the previous year. Clinical serologic, and social characteristics were studied more closely in 98 of the 145 homosexual men. Verification of hepatitis A was made by a solid-phase radioimmunoassay technique for detection of antibody to hepatitis A virus of the immunoglobulin M class. In addition, 64% of the men showed findings consistent with a prior hepatitis B (antibody to hepatitis B core antigen and/or antibody to hepatitis B surface antigen) and 34% were Treponema pallidum immobilization-positive from a prior or concomitant syphilis. Employment in risk professionals was common; thus, 19% worked in restaurants or otherwise handled food and 20% were engaged in medical care as compared to the 1% occupied in either branch of work among the general population in Sweden. Sexual habits with multiple partners and oral-anal sexual contacts were judged to be of major importance in the spread of this epidemic. Some spread of hepatitis A to the general population probably occurred due to the risk occupations of many homosexual men.
There is a paucity of data describing the risk of acquiring hepatitis A while traveling in the developing world. This paper uses available data to calculate the risk to Canadian travelers.
Information was gathered from Canadian and international sources on the following: the yearly incidence of hepatitis A among Canadians; the proportion of cases of hepatitis A associated with travel to developing countries; the number of days of such travel by Canadians per year; and the percentage of travelers immunized before departure. Calculations were performed on these figures to arrive at an estimated risk of infection for unimmunized Canadian travelers.
The annual incidence of hepatitis A in Canada over the period 1996-2001, adjusted for underreporting, averaged 6.15 cases/100,000 people. During that time, Canadians traveled approximately 36.5 million days/year in developing countries. The literature shows that 4% to 28% (mean 16%) of cases are estimated to have been acquired abroad. It also shows that 14% to 24% (mean 19%) of such travelers are immunized before departure. Based on these figures, the risk of acquiring hepatitis A during 1 month of travel in the developing world is calculated to be approximately 1 case per 3,000 unimmunized travelers.
Hepatitis A is an important travel-related disease, preventable by immunization. However, our calculations indicate that the risk of acquiring hepatitis A while traveling in the developing world is lower than some previously published estimates. The results represent an average for all types of travel to all such countries. The actual risk will vary considerably, depending on the destination and style of travel.
We evaluated three established statistical models for automated 'early warnings' of disease outbreaks; counted data Poisson CuSums (used in New Zealand), the England and Wales model (used in England and Wales) and SPOTv2 (used in Australia). In the evaluation we used national Swedish notification data from 1992 to 2003 on campylobacteriosis, hepatitis A and tularemia. The average sensitivity and positive predictive value for CuSums were 71 and 53%, for the England and Wales model 87 and 82% and for SPOTv2 95 and 49% respectively. The England and Wales model and the SPOTv2 model were superior to CuSums in our setting. Although, it was more difficult to rank the former two, we recommend the SPOTv2 model over the England and Wales model, mainly because of a better sensitivity. However, the impact of previous outbreaks on baseline levels was less in the England and Wales model. The CuSums model did not adjust for previous outbreaks.