Comparative study of Fanconi anemia in children of different ethnic origin in South Africa.

A comparative study of clinical, hematologic, and cytogenetic findings was made in 40 black and 35 white children with Fanconi anemia. The black children were Bantu-speaking Negroid stock of diverse tribal origin. The white children were predominantly Afrikaans stock of Dutch/German/French Huguenot origin. All of the patients had IFAR scores of 2 to 4+ and over 80% in each group had increased spontaneous and/or mutagen-induced chromosomal breakage (CB-positive). There were no significant clinical differences between black and white patients or between CB-pos and CB-neg patients, with the exception of white children in whom significantly more CB-pos patients had thumb and radial anomalies than the CB-neg patients. The age-at-onset of hematologic manifestations was the same for all groups, but more black than white CB-pos patients were severely anemic at the time of diagnosis. Response to androgen and steroid therapy occurred in only 33% of black children compared with 86-90% of white children; 81% of black patients died during the 18 year study period compared with 30% of white children, but the age at death was similar. More sophisticated studies are required to determine whether these differences are genetically determined or related to cultural, educational, and socio-economic differences between the two ethnic groups.

Pattern of 6-mercaptopurine urinary excretion in children with acute lymphoblastic leukemia: urinary assays as a measure of drug compliance.

A method for the measurement of 6-mercaptopurine (6MP) in urine using high-performance liquid chromatography is described. Urinary excretion of 6MP was measured in 46 children with acute lymphoblastic leukemia. The proportion of unchanged drug excreted after oral dosage in the morning was greater than after an evening dose (5.6 +/- 3.3% vs. 3.3 +/- 2.4%). Possible reasons for the discrepancy are discussed. In all children receiving 6MP in the morning, the drug was detected in urine at 2 and 4 h after ingestion. At 6 h, 6MP was still detectable in 77% of patients, at 8 h in 54%, at 10 h in 12%, and at 12 h in 8%. The reliability of urinary 6MP determination as a measure of drug compliance was assessed in 39 children accustomed to receiving their medication in the evening. 6MP was detected in 81% of first morning urine samples, indicating compliance with medication the preceding evening. The absence of 6MP in first morning urine samples did not necessarily indicate poor compliance because of the variability in 6MP excretion and unpredictable pattern of night voiding in children. The method was therefore a reliable measure of good short-term compliance. It also directed attention toward possible noncompliance in children with negative samples.

Compliance with chemotherapy in childhood leukaemia in Africa.

Compliance with chemotherapy in childhood leukaemia is usually good because of parental fear of the disease. However, poor compliance and refusal of treatment have been reported from both the USA and the UK. Little is known about African concepts of leukaemia, attitudes to treatment or compliance. A study was undertaken to investigate factors which might affect compliance in 15 black and 30 white families of leukaemic children in Johannesburg. The socio-economic and educational status of the black families was lower than that of the white. Only 53% of black children attended hospital on the appointed day compared with 90% of white children. Less than 50% of black parents understood the nature of their child's illness. Both black and white families had unused medication at home. White parents more frequently reported toxic effects related to chemotherapy and more white children than black children exhibited lymphopenia during maintenance therapy. Assessment of drug compliance should be included as an independent variable when evaluating factors affecting response to chemotherapy in communities of diverse ethnic, socio-economic and cultural backgrounds.

The mechanical transmission of hepatitis B virus by the common bedbug (Cimex lectularius L.) in South Africa.

Tests for both hepatitis B surface antigen (HBsAg) and hepatitis e antigen (HBeAg) were carried out on wild-caught and laboratory-colonized bedbugs (Cimex lectularius L.), the latter after hepatitis B virus (HBV)-positive blood-meals. Positivity for both antigens was interpreted as an indication of HBV infectivity. Of 22 pools in which were tested 211 bugs collected in the northern Transvaal, 18 were HBsAg-positive and 17 HBeAg-positive, with estimated infection rates of 156,7 and 137,7 per 1000 bugs respectively. Passage of HBV in bugs, allowing an extrinsic incubation period of 57-69 days, resulted in 19 out of 25 bugs being positive for HBsAg after the first passage; only a small number of these were positive for HBeAg. After the second passage all bugs tested were HBsAg-negative, showing that the virus had disappeared. Tests on the salivary glands and carcass of each bug at intervals up to 31 days after an infective meal showed a positivity rate of 98% (HBsAg) and 17% (HBeAg) for carcasses and 20% (HBsAg) and 0% (HBeAg) for salivary glands. Attempts to detect HBV particles in the salivary glands by electron microscopy failed. Bugs were shown to continue to excrete HBsAg in their faeces up to the 42nd day, and both HBsAg and HBeAg together up to the 30th day. HBsAg particles were only detected by electron microscopy in faeces harvested on the 10th day. The results as a whole indicate that no biological multiplication of virus occurs in C. lectularius but that mechanical transmission from insects to man could occur by: (i) contamination of a person when crushing infective bugs; (ii) contamination from infected faeces; and (iii) infection by bite due to regurgitation or interrupted feeding.

Transmission experiments with hepatitis B surface antigen and the common bedbug (Cimex lectularius L).

Hepatitis B surface antigen (HBsAg)-positive blood meals were fed to a colony of the common bedbug (Cimex lectularius L) in a series of 5 experiments. Antigen persisted in the bugs for at least 7 1/2 weeks, but was undetectable after 18 weeks. Trans-stadial transmission was demonstrated through one moult only, and transovarial transmission did not occur. Antigen was successfully transmitted by adult bugs into 3 out of 35 canisters of HBsAg-negative blood. Antibody of HBsAg was detected in the serum from a rabbit on which HBsAg-positive adult bugs had fed as well as in the serum of 2 out of 10 guinea-pigs on which HBsAg-positive 4th and 5th nymphal instars had fed. The results as a whole indicate that biological multiplication and biological transmission do not occur in C. lectularius, but mechanical transmission has been demonstrated. This is probably an important means of hepatitis B virus transmission among humans in South Africa.

Infection of the common bedbug (Cimex lectularius L) with hepatitis B virus in South Africa.

A total of 1 368 bedbugs of the species Cimex lectularius L were collected mainly from huts in villages or on farms at 6 localities in the northern Transvaal. They were tested in pools of 10 for the presence of hepatitis B surface antigen (HBsAg). None of 20 pools from Pietersburg was HBsAg-positive, but 32 out of 120 pools from the 5 other localities were HBsAg-positive. Estimated infection rates per 1 000 bugs were 17,1 (Messina), 24,9 (Waterpoort), 28,4 (Letaba), 54,5 (Potgietersrus) and 67,0 (Louis Trichardt), with an overall rate of 30,6. Seventeen out of 57 pools of the engorged bugs (infection rate 34,8) and 14 out of 62 pools of the unengorged bugs (infection rate 25,3) were HBsAg-positive. These very high infection rates, even in unengorged bugs, suggest that C. lectularius could be a vector of hepatitis B virus in the Transvaal, and that the varying degrees of infestation could explain the markedly different HBsAg-positive frequencies previously shown in sera collected from different population groups in that province.