Prevalence of hepatitis A, B, C and human immunodeficiency virus seropositivity among patients with acute icteric hepatitis at the Kenyatta National Hospital, Nairobi.

OBJECTIVE: To determine the prevalence of hepatitis A, B, C and HIV seropositivity among patients with acute icteric hepatitis. DESIGN: Cross-sectional descriptive survey. SETTING: Kenyatta National Hospital, Nairobi. SUBJECTS: Eighty four patients aged above six months with a history of jaundice not exceeding six months were recruited. There were 47 males and 17 females with an age range of eight months to 67 years and a median age of 25 years. METHODS: History was obtained physical examination done and blood taken for determination of bilirubin, ALT, AST and ALP levels. Sera that had disproportionately greater transaminase than ALP elevation were assayed for IgM anti-HAV, IgM anti-HBc, HbsAg, anti-HCV and anti-HIV antibodies. RESULTS: Evidence of hepatitis A, B, and C was round in 41.7%, 26.2%, and 7.1% of the patients respectively, 13.1% of the patients were HBsAg carriers while 30.1% of all patients were HIV positive. Thirty two patients did not have evidence of hepatitis A, B, or C infection and this group was significantly associated with HIV infection (p = 0.003). CONCLUSION: Hepatitis A was the commonest overall type of acute icteric hepatitis seen at the KNH, and among patients aged 15 years and below. Hepatitis B was the leading identified cause of acute hepatitis among those aged over 15 years. Hepatitis C accounted for 7.1% of acute icteric hepatitis 30.1% of all patients and 50% of those admitted with acute hepatitis were also HIV positive.

T-cell subset counts and serum immunoglobulin concentrations in patients with chronic renal failure at the Kenyatta National Hospital.

This study was designed to determine whether there was any difference in the T-cell subset counts and serum immunoglobulin concentrations in patients with chronic renal failure as compared to normal controls. Ninety individuals participated in the study. These were divided into three groups as follows; (i) 30 subjects with normal renal function; (ii) 30 subjects with chronic renal failure (CRF)(creatinine clearance 10-50 mls/min), not requiring haemodialysis and; (iii) 30 subjects with end stage renal disease (creatinine clearance < 10 mls/min) on haemodialysis. The subjects in the three groups were matched for age and sex. In addition, it was ascertained that none of the subjects was on any medication or suffered from any ailment known to interfere with the immune system. The T-cell subset counts were carried out using flow cytometry while the serum concentration of immunoglobulins was measured using the radio-immunodiffusion method. Patients with CRF, whether on haemodialysis or not, had significantly lower lymphocyte counts as a proportion of total white cell count (19% and 19.2% respectively versus 39%) and low absolute CD4 cell counts per mm3 (337 +/- 94 and 449 +/- 116 respectively versus 891 +/- 360) and CD8 cell counts per mm3 (437 +/- 234 and 490 +/- 176 respectively versus 644 +/- 228) as compared to normals, with no statistically significant difference between the two groups with CRF. The CD4: CD8 ratios in the three groups studied were 1.487 +/- 0.233, 0.961 +/- 0.326 and 0.751 +/- 0.167 respectively, being significantly higher in normal controls than in any of the groups with CRF (p < 0.05) and in the group with CRF not requiring dialysis than in those requiring it (p < 0.05). The serum concentration of immunoglobulins in the two groups with CRF were similar to those in the group with normal renal function. It is concluded that CRF represents a state of immunodeficiency not significantly corrected by haemodialysis.

High levels of TNF, soluble TNF receptors, soluble ICAM-1, and IFN-gamma, but low levels of IL-5, are associated with hepatosplenic disease in human schistosomiasis mansoni.

In a case-control study based in two areas of Kenya, hepatosplenic schistosomiasis mansoni was shown to be linked with low levels of IL-5 and with correspondingly high IFN-gamma, TNF, and circulating soluble TNF receptor I (sTNFR-I), sTNFR-II, and sICAM-1. PBMC from the hepatosplenic cases responded to in vitro Ag stimulation with significantly higher levels of IFN-gamma and TNF, but lower levels of IL-5, compared with nonhepatosplenic controls matched for age and infection intensity. Most of these correlations were confounded by differences between geographical areas. However, principle component analysis identified a high IFN-gamma and TNF, and low IL-5 axis in the data as the first principle component; this was significantly associated with hepatosplenomegaly (p < 0.0005) even after controlling for area. High plasma levels of sTNFR-I (p < 0.001), sTNFR-II, (p < 0.0001), and sICAM-1 (p < 0.009) were also significantly associated with hepatosplenomegaly, independently of area, in the case of the soluble forms of both TNF receptors. These parameters were negatively related to IL-5. These results suggest that proinflammatory cytokines are involved in the hepatosplenic disease process in infected individuals who have low anti-inflammatory Th2 responses and that sTNFR may be a useful circulating marker for this disease process, perhaps reflecting the level of TNF activity in hepatic tissues.

Serum tumour necrosis factor in children suffering from Plasmodium falciparum infection in Kilifi District, Kenya.

Tumour necrosis factor-alpha (TNF alpha) levels were measured by bioassay and immunoassay in sera of children infected with Plasmodium falciparum and uninfected children in the same community in Kilifi District, Kenya. Seventy-one children, mean age 2.9 years (range 4 months-6.8 years), were enrolled; 34 children had severe malaria, 23 had mild (non-severe) malaria and 14 had no malaria. TNF alpha levels were significantly elevated in children with severe malaria compared with those with non-severe malaria and the uninfected group (P < 0.001 and P < 0.00001, respectively). The levels correlated directly with parasite densities (r = 0.54, P < 0.002). Among the children with severe malaria, TNF alpha levels correlated directly with the degree of anaemia but inversely with age. High tumour necrosis factor levels were associated with manifestations of severe malaria infection but declined to normal levels after effective antimalarial treatment.

Vaccination of the vervet monkey (Cercopithecus aethiops) against infection with Schistosoma mansoni.

Pilot experiments were carried out to assess the immunizing potential of radiation-attenuated cercariae of S. mansoni. Groups of 4 monkeys each were vaccinated 4-5 times at 3-5-week intervals using cercariae which had received 10, 20, 40 or 60 krad of gamma radiation. Animals were vaccinated with 1000 or 2000 cercariae per kilogram of body weight. Overall the difference in worm burdens between the vaccinated and unvaccinated groups was highly significant (P greater than 0.01). The highest level of protection achieved was 44.4%. This was in monkeys which were immunized five times with 2000, 20-krad cercariae at 3-4-week intervals. Protection levels of 33.3%, 36.6% and 37.0% were achieved in groups which had received, respectively, 1000 20-krad cercariae, 1000 10-krad cercariae, 2000 40-krad cercariae and 2000 60-krad cercariae. Vaccination reduced faecal egg counts markedly and intestinal tissue egg counts by 20-40%. Antischistosomular antibody was detectable in vitro 3 weeks after the first vaccination. Schistosomule kill rates of up to 60% were observed in vitro.

The effect of temperature on the rate of transmission of Theileria parva parva infection to cattle by its tick vector, Rhipicephalus appendiculatus.

A steer was infected with Theileria parva parva Kilae stabilate; nymphal Rhipicephalus appendiculatus ticks were applied to its ears so that they completed repletion when the steer had a high piroplasm parasitaemia. The engorged nymphs were subsequently incubated at 28 degrees C for 26-29 days to complete moulting, when the adult ticks were divided into two groups; one was incubated at 18 degrees C for 20 days and the other at 18 degrees C for 14 days and then at 37 degrees C for 6 days. Groups of ticks incubated at 37 and 18 degrees C were triturated and each resultant supernatant fluid inoculated into a steer. Both steers became infected, but the 37 degrees C supernatant group showed a much shorter pre-patent period to schizonts. Groups of ticks incubated at 37 or 18 degrees C were applied to pairs of cattle for 24, 48 and 72 h and then removed. There was a more rapid transmission of theileriosis to cattle by ticks kept at high ambient temperatures compared to those kept at low ambient temperatures. All cattle on which ticks treated at 37 degrees C were applied developed acute and fatal T. parva infection irrespective of the duration of tick application, while only 1 animal receiving ticks treated at 18 degrees C and fed for 72 h developed infection. The pre-patent period for macroschizonts was very short in all the groups receiving ticks incubated at 37 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)