A new variant of GB virus C/hepatitis G virus (GBV-C/HGV) from South Africa.

Phylogenetic analysis of the 5' non-coding region (5'NCR) sequences has demonstrated that GB virus C/hepatitis G virus (GBV-C/HGV) can be separated into three major groups that correlate with the geographic origin of the isolate. Sequence analysis of the 5'NCR of 54 GBV-C/HGV isolates from 31 blood donors, 11 haemodialysis patients and 12 patients with chronic liver disease suggests the presence of a new variant of GBV-C/HGV in the province of KwaZulu Natal, South Africa. Eleven isolates grouped as group 1 variants (bootstrap support, 90%) found predominantly in West and Central Africa, a further six isolates grouped as group 2 variants (bootstrap support, 58%) found in Europe and North America; five of which grouped as 2a (bootstrap support, 91%) and one as 2b (bootstrap support, 87%), the latter also includes isolates from Japan, East Africa and Pakistan. Although the remaining 37 GBV-C/HGV isolates were more closely related to group 1 variants (bootstrap support, 90%), they formed a cluster, which was distinct from all other known GBV-C/HGV sequences. None of the South African isolates grouped with group 3 variants described from Southeast Asia. Three variants of GBV-C/HGV exist in KwaZulu Natal: groups 1, 2 and a new variant, which is distinct from other African isolates.

Seroepidemiological study of Helicobacter pylori infection in South African children.

The seroepidemiology of Helicobacter pylori infection was studied in 681 randomly selected Black children from newborn to 13 years of age (333 boys, mean age 8.05 years, and 348 girls, mean age 7.76 years) in KwaZulu/Natal, South Africa. H. pylori infection was identified serologically using an enzyme-linked immunosorbent assay to detect the presence of immunoglobulin G against H. pylori. Demographic information collected included age, gender, family income, overcrowding, educational level, and possession of domestic pets. The seroprevalence of H. pylori infection was compared to a known faecal-orally transmitted infection, hepatitis A virus (HAV); 66% of the children were seropositive for H. pylori. There was an age-specific increase in H. pylori infection, with more than 80% of children being infected by the age of 10 years. There was no significant difference (P = 0.338) in the seropositivity of H. pylori infection between boys (68%) and girls (64%), nor was there any significant difference in H. pylori infection related to pets, level of parents' education, crowding, and income, by either univariate or multivariate analysis. However, there was a significant association (P < 0.00001) between the seroprevalence of H. pylori and HAV infections, suggesting similar modes of transmission.

Elevated adenosine deaminase activity in patients with HIV and tuberculous peritonitis.

OBJECTIVE: To evaluate the diagnostic potential of the ADA(T), ADA isoenzymes (ADA1 and ADA2) and the interferon-gamma (IFN-gamma) test in HIV-seropositive patients with tuberculous peritonitis. METHODS: Ascitic ADA(T), ADA1, ADA2 and IFN-gamma were prospectively evaluated in HIV-seronegative patients with tuberculous peritonitis (n = 17), HIV-seropositive patients with tuberculous peritonitis (n = 6) and in patients with cirrhosis (n = 22) and malignancy (n = 5). RESULTS: ADA(T) and ADA2 isoenzyme activities of HIV-seronegative (ADA(T) = 109 U/l; ADA2 = 94 U/l) and HIV-seropositive (ADA(T) = 109.5 U/l; ADA2 = 95.5 U/l) patients with tuberculous peritonitis, respectively, were significantly different (P < 0.001) from patients with cirrhosis (ADA(T) = 10.5 U/l; ADA2 = 8 U/l) and malignancy (ADA(T) = 13 U/l; ADA2 = 11 U/l). There was no significant difference in ADA(T) and ADA2 activities between HIV-seropositive and seronegative patients with tuberculous peritonitis. There was no significant correlation between ADA, its isoenzymes and IFN-gamma. CONCLUSIONS: The diagnosis of tuberculous peritonitis can be made by a sensitive, relatively non-invasive procedure in both HIV-seronegative and seropositive patients with minimal risk to the patient and the investigator. The diagnostic value of ADA(T) is not enhanced by measuring ADA isoenzymes or IFN-gamma.

Evaluation of the "one-minute" test for detecting Helicobacter (Campylobacter) pylori infection.

The "one-minute" urease test to detect Helicobacter (Campylobacter) pylori infection was evaluated using histology and culture as the "gold standard". The test was performed in a blinded manner and compared with the conventional Christensen's urease test. Helicobacter pylori was detected in 88 of 100 consecutive patients attending the gastrointestinal clinic for upper endoscopy. Although the "one-minute" urease test was more sensitive [86% (76/88)] than the conventional Christensen's urease test [70% (62/88)], this difference was not statistically significant (P = 0.22). Histology was the most sensitive [97% (85/88)] whilst culture was 80% (70/88) sensitive. All tests exhibited specifications of 100%. The "one-minute" urease test is a simple, rapid and highly specific test to detect Helicobacter pylori which can be performed at endoscopy.

Detection of Entamoeba histolytica immunoglobulins G and M to plasma membrane antigen by enzyme-linked immunosorbent assay.

Sixty-one serum specimens from 22 patients with clinically diagnosed amoebic liver abscess (ALA), 10 hospitalized patients with a variety of diseases other than amoebiasis, 12 normal healthy controls, and 17 subjects from an amoebiasis-endemic area were assayed by enzyme-linked immunosorbent assay (ELISA). The plasma membrane fraction of axenic cultures of Entamoeba histolytica HK9 separated from other subcellular fractions by differential centrifugation was used as the antigen to detect specific immunoglobulin G (IgG) and IgM antibodies. Using a single serum dilution of 1/100 and optical densities at 492 nm of 0.200 and 0.250 as the cutoff values for the IgM and IgG ELISAs, their respective sensitivities in 22 ALA patients were 91% (20 of 22) and 95% (21 of 22). In 22 patients (10 hospitalized and 12 normal healthy controls), the specificities of the IgM and IgG ELISAs were 95% (21 of 22) and 91% (20 of 22), respectively. All five asymptomatic carriers of pathogenic E. histolytica were seropositive by the IgG ELISA and the amoebic gel diffusion test (AGDT). The AGDT was positive for three of six culture-negative controls, while the IgG ELISA was positive for all six. For six asymptomatic carriers of nonpathogenic zymodemes, the AGDT was positive for two, and the IgG ELISA was positive for three. There was an excellent correlation (r = 0.96) between the IgG ELISA and the AGDT. Only one of six culture-negative controls, none of the asymptomatic carriers of pathogenic E. histolytica, and one of six carriers of nonpathogenic E. histolytica were seropositive by the IgM ELISA, thus highlighting the specificity of the IgM ELISA in the diagnosis of ALA. It is believed that the use of plasma membrane fractions has improved the diagnostic potential of the IgM ELISA.

Hepatitis C virus infection in chronic liver disease in Natal.

The aim of this cross-sectional seroprevalence study was to determine the prevalence of antibodies to hepatitis C virus (HCV) (anti-HCV) in patients with cirrhosis, hepatocellular carcinoma (HCC) and chronic active hepatitis (CAH) attending a referral hospital in a hepatitis B virus (HBV)-endemic area in South Africa. One hundred and ten patients with suspected cirrhosis, 44 with suspected HCC and 6 with chronic hepatitis were initially included. The diagnoses were confirmed in 77 patients with cirrhosis (histologically or macroscopically at peritoneoscopy), 33 patients with HCC (histologically or elevated alpha-fetoprotein levels plus focal lesion on hepatic imaging) and 6 patients with CAH (histologically) without antinuclear antibodies. All patients were tested for anti-HCV with the Abbott second-generation enzyme immunoassay combined with a supplemental neutralisation assay, and hepatitis B surface antigen (HBsAg). Anti-HCV seroprevalence for cirrhosis, HCC and CAH were 18/77 (23%), 8/33 (24%) and 2/6 (33%) respectively. HBsAg was detected in serum in 16 (21%), 15 (46%) and 1 (17%) patient respectively. Only 1 patient (with cirrhosis) was positive for both anti-HCV and HBsAg. Of those who were anti-HCV-positive, 4/18 (22.2%) cirrhotics, none with HCC and 1/2 (50%) with CAH, had previously received blood transfusions, resulting in a cumulative frequency of 5/28 (18%). Our results indicate that HCV is an important aetiological agent in the pathogenesis of chronic liver disease in our patients. In the majority of patients (82%), the infection was not transfusion-related. Thus, screening of blood donors for anti-HCV would not prevent the majority of cases of chronic liver disease secondary to HCV. It appears as if HCV and HBV have different modes of transmission in southern Africa.

GB virus C/hepatitis G virus infection in KwaZulu Natal, South Africa.

Sera from 70 patients on maintenance haemodialysis, 98 patients with chronic liver disease, and 232 volunteer blood donors in the province of KwaZulu Natal, South Africa, were screened for GB virus/hepatitis G virus (GBV-C/HGV) RNA and anti-E2 by reverse transcription-polymerase chain reaction (RT-PCR) and by an enzyme-linked immunosorbent assay (ELISA), respectively. GBV-C/HGV RNA was detected in 17/70 (24.3%) haemodialysis patients, 12/98 (12.2%) patients with chronic liver disease, and 44/232 (18.9%) blood donors (Africans [29/76; 38.2%]; Asians [2/52; 3.8%]; Whites [11/49; 22.4%], and "Coloureds" [persons of mixed origin; 2/55; 3.6%]). Overall (anti-E2 and/or RNA) 43.9% (43/98) of patients with chronic liver disease, 47.1% (33/70) of haemodialysis patients, and 31.9% (74/232) of blood donors (Africans [44/76; 5.9%]; Asians [5/52; 9.6%]; Whites [15/49; 30.6%], and Coloureds [9/54; 16.6%]) were exposed to GBV-C/HGV infection. There was a significant difference in the prevalence of GBV-C/HGV infection (RNA and/or anti-E2) between African blood donors and the other racial groups (P < .001), and between blood donors and haemodialysis patients (P = .02) and patients with chronic liver disease (P = .04). Anti-E2 antibodies and GBV-C/HGV RNA were almost mutually exclusive. GBV-C/HGV-infected haemodialysis patients received more transfusions (P = .03) than noninfected patients. There was no significant difference in liver biochemistry between GBV-C/HGV-infected and noninfected patients and between blood donors in each of the four racial groups. The high prevalence of GBV-C/HGV infection in blood donors and chronic liver disease patients, and the lack of elevated liver enzymes and clinical hepatitis in blood donors and haemodialysis patients, suggest that GBV-C/HGV may not be associated with liver disease.

Evaluation of an enzyme-linked immunosorbent assay in the serodiagnosis of amoebic liver abscess.

An indirect enzyme-linked immunosorbent assay (ELISA) was evaluated for the detection of anti-amoebic IgG and IgM antibodies to assess its value in distinguishing past from current infection in invasive amoebiasis, particularly in amoebic liver abscess (ALA) patients. Using sera from 295 individuals, the ELISA was also compared with the amoebic gel diffusion (AGD) test. In 100 patients the IgG-ELISA at a single test dilution of 1/6,400 had a sensitivity of 99% for clinically diagnosed ALA. In these same patients the IgM-ELISA at a single dilution of 1/400, had a sensitivity of 64% and a specificity of 97.9%. No cross-reactions were observed in sera from patients with collagen vascular disease. In 121 patients without clinical invasive amoebiasis, 8 were AGD-positive and 12 were IgG-ELISA-positive, giving the latter assay a specificity of 91.7%. This is thought to be due to past infection with Entamoeba histolytica. In symptomless carriers of pathogenic zymodemes, 10/11 were seropositive by the IgG-ELISA and 11/11 by the AGD test. There was an excellent correlation between the IgG-ELISA and the AGD test (r = 0.99). The IgG-ELISA is a sensitive, specific, simple and rapid test. It has the clinical advantage that results are obtainable 2 1/2 hours after receipt of the specimen, compared with the 24-48 hours required for the AGD test. The prompt availability of IgG-ELISA results could prove advantageous for implementation of early therapy. The IgM-ELISA was not found to be sensitive enough to be used as an index of active amoebic infection.

Diagnosis of tuberculosis by detection of mycobacterial antigen in pleural effusions and ascites.

We describe a method for the diagnosis of pleural and peritoneal tuberculosis by the detection of tuberculous antigens using an enzyme-linked immunosorbent assay. Eleven tuberculous pleural fluid and 10 tuberculous ascitic fluid samples were studied by this technique, using 10 non-tuberculous pleural fluid and 14 non-tuberculous ascitic fluid samples as controls. An absorbance value of 0.3 was found to separate the tuberculous groups from their controls to a statistically significant extent (ascitic fluid P less than 0.05; pleural fluid P less than 0.01).

Racial differences in the seroprevalence of hepatitis A virus infection in Natal/KwaZulu, South Africa.

The age- and race-specific seroprevalence of hepatitis A virus (HAV) infection was determined by radioimmunoassay (RIA) in 786 subjects between the ages of 6 months to 60 years. More than 50% of African children were seropositive by the age of 5 years. In blood donors (17-60 years), 50% (93/187) of Whites, 67% (110/163) of Indians, 85% (117/137) of Coloureds, and 91% (115/127) of Africans were seropositive. There was a significant difference in the seroprevalence of HAV infection between White blood donors and blood donors from the other three racial groups [Coloureds (P < 0.0001), Africans (P < 0.0001), and Indians (P < 0.001)] and between Indians and Coloureds (P < 0.0001) and Indians and Africans (P < 0.0001). There was no significance difference in HAV infection between Coloureds and Africans (P < 0.200). Eighty-seven per cent (32/37) of rural Africans had previous infection. In the African population HAV infection is acquired in childhood. There are significant racial differences in the seroprevalence of HAV infection. The surveillance of HAV infection may be used as a valuable yardstick to monitor the changing standards of hygiene and socioeconomic conditions of a community in transition in South Africa and to make rational public health decisions regarding a hepatitis A vaccination policy.

Evaluation of various laboratory techniques to diagnose Helicobacter pylori in patients with upper gastro-intestinal tract symptoms.

Helicobacter (Campylobacter) pylori is strongly associated with type B gastritis. The detection of H. pylori, which entails histological examination and culture of gastric biopsy specimens, takes several days. There has been much interest in developing more rapid tests, including non-invasive ones. Using histology and/or culture as the 'gold standard', several methods to detect H. pylori were compared and evaluated. The organism was detected in 84 of 100 consecutive patients attending the Gastrointestinal Unit of King Edward VIII Hospital for upper gastrointestinal tract endoscopy. Histological examination was the most sensitive (98%) and specific (100%) method used in detecting H. pylori in gastric biopsy specimens. An enzyme-linked immunosorbent assay to detect specific IgG antibodies to whole H. pylori organisms is a moderately sensitive (82%), non-invasive method but it is nonspecific (38%). Although culture was specific (100%), it was less sensitive (68%) than histological examination. The 'conventional' urease assays must be performed under controlled conditions (37 degrees C) for optimal results (sensitivity, 71%).

Phylogenetic analysis of GBV-C/hepatitis G virus.

Comparison of 33 epidemiologically distinct GBV-C/hepatitis G virus complete genome sequences suggests the existence of four major phylogenetic groupings that are equally divergent from the chimpanzee isolate GBV-C(tro) and have distinct geographical distributions. These four groupings are not consistently reproduced by analysis of the virus 5'-noncoding region (5'-NCR), or of individual genes or subgenomic fragments with the exception of the E2 gene as a whole or of 200-600 nucleotide fragments from its 3' half. This region is upstream of a proposed anti-sense reading frame and contains conserved potential RNA secondary structures that may be capable of directing the internal initiation of translation. Phylogenetic analysis of this region from certain South African isolates is consistent with previous analysis of the 5'-NCR suggesting that these belong to a fifth group. The geographical distribution of virus variants is consistent with a long evolutionary history that may parallel that of pre-historic human migrations, implying that the long-term evolution of this RNA virus is extremely slow.

Ascitic fluid gamma interferon concentrations and adenosine deaminase activity in tuberculous peritonitis.

The gamma interferon (gamma-IFN) concentration and the adenosine deaminase (ADA) activity were evaluated in 30 patients with tuberculous peritonitis, 21 patients with ascites due to a malignant disorder, and 41 patients with cirrhosis. The gamma-IFN concentrations were significantly higher (p < 0.0001) in tuberculous peritonitis patients (mean: 6.70 U/ml) than in the malignant (mean: 3.10 U/ml) and cirrhotic (mean: 3.08 U/ml) groups. Use of a cut off value of > or = 3.2 U/ml gave the assay a sensitivity of 93% (25 of 27), a specificity of 98% (54 of 55), positive (P+) and negative (P-) predictive values of 96% and a test accuracy of 96%. The ADA activity was significantly (p < 0.0001) higher in the tuberculous peritonitis group (mean: 101.84 U/l) than in the control groups (cirrhosis (mean: 13.49 U/l) and malignancy (mean: 19.35 U/l)). A cut off value of > 30 U/l gave the ADA test a sensitivity of 93% (26 of 28) a specificity of 96% (51 of 53), a (P+) value of 93%, a (P-) value of 96%, and a test accuracy of 95%. There was a significant (p < 0.0001) correlation (r = 0.72) between ADA activity and gamma-IFN values in patients with tuberculous peritonitis. These results show that a high concentration of gamma-IFN in ascitic fluid is as valuable as the ADA activity in the diagnosis of tuberculous peritonitis. Both are rapid non-invasive diagnostic tests for tuberculous peritonitis.