Biomedical subjects
Publications and source records attributed to I Mohammed.
Epidemiological evidence is summarized for associations of ABO blood group and secretor status with susceptibility to invasive disease due to capsulate organisms responsible for the majority of bacterial meningitis. Host-parasite interactions that might underly these findings are proposed and evidence to support or refute them provided.
Serological investigations on female prostitutes resident in Borno State in northeastern Nigeria have shown that the seroprevalence of HIV-1 infection has increased 9.81%--fold in one year. The highest sero-prevalence rates were found amongst prostitutes who had not benefited from previous health education campaigns. Prostitution appears to be on the increase in spite of AIDS probably because of the difficulty in finding alternative means of making a living. Attempts to halt the spread of HIV infection are hampered by the fact that most prostitutes are indifferent to the use of condoms and do not appreciate the importance of protecting themselves from the risks of HIV infection. Their frequent mobility also poses a problem as it makes it difficult for them to benefit from health education campaigns. The prevalence of HIV-1 infection among female prostitutes in Borno State (as indeed in other States in Nigeria) is likely to rise sharply in the next few years unless serious efforts are made to intensify health education campaigns targeted at the high risk groups.
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Immune complex levels were measured in serum and synovial fluid obtained from 10 patients who developed arthritis 3-8 days after the onset of meningococcal meningitis. Mean serum immune complex levels were lower in these patients than in eight age matched control patients with meningococcal disease who did not develop late complications. This observation suggests that meningococcal arthritis follows local formation of immune complexes in the synovium rather than deposition of circulating immune complexes. Purified meningococcal polysaccharide antigen-induced synovitis when injected into the knee of rabbits previously sensitized by i.v. injection with heat killed meningococci.
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Mass vaccination campaigns were mounted by several state governments in the northern Nigerian sector of the African meningitis belt. Bivalent groups A and C polysaccharide vaccines were used. The results of these campaigns in four of the states which are adjacent to each other are presented and assessed. A total of 7535350 persons in the four States, Bauchi, Borno, Gongola and Plateau, were given the vaccine over a period of 4 years (1978-1981). There was a decline in the overall number of cases reported as well as in the number of deaths in the area, where, since 1978, there has not been an epidemic of meningococcal meningitis. Variations were observed among the states which vaccinated over 50% of their populations and had many fewer cases than those which did not. These results show that mass vaccination is an effective means of preventing outbreaks of meningococcal meningitis and may lead to eradication of the disease.
Meningococcal antibody was measured in 928 persons vaccinated with combined groups A and C polysaccharide antigens in Bauchi State, Nigeria between 1979 and 1982. Protective amounts of antibody were detected by the indirect haemagglutination technique up to 4 years after vaccination. This persistence was observed mainly in adults, although a substantial proportion of older children also had persistent antibody. Titres in younger children fell progressively, and by the third year the mean log2 antibody titre was 1.4; this may not confer protection against disease. A rational policy for vaccination against meningococcal meningitis would be to revaccinate younger children after 2 years, older children after 4 years, and adults after 6-8 or more years.
During a one-year prospective study, the clinical conditions in which Listeria monocytogenes was isolated from nineteen patients (six females, thirteen males) included meningitis, meningoencephalitis, spontaneous peritonitis, septicaemia, arthritis, pelvic infection and urethritis. All isolates were type 4 serotype. Both apparently well persons and patients with already compromised immune systems were observed. Subtyping of ascitic fluid lymphocytes in one patient with peritonitis showed predominantly T cell subpopulation and no B cells. Most isolates were sensitive to ampicillin, crystalline penicillin and erythromycin. A mortality of 27 per cent was recorded.
Glycosylated haemoglobin (HbA1) was determined by a microcolumn technique using Biorex 70 resin in normal Nigerians and in patients with diabetes, iron deficiency anaemia, sickle cell disease and renal failure. Mean %HbA1 was 10.0 +/- 1.9% in controls which is higher than levels reported in Caucasians. HbAS but not HbSS had a reducing effect on the %HbA1 which was also found elevated in iron deficiency anaemia and diabetes mellitus. Factors peculiar to tropical medical practice affecting glycosylated haemoglobin must be appreciated and further investigated to assess the usefulness of HbA1 determination in the long term control of diabetes mellitus.
The post-vaccination antibody response to both Group A and Group C meningococcal polysaccharide antigen was studied in 397 male and 359 female vaccinated persons aged between 4 and 40 years from Bauchi Town and neighbouring villages in Nigeria. No difference in response was observed between the sexes. Highest antibody levels occurred in those aged between 13 and 28 years. Haemoglobin genotype did not affect response. Malnourished children had significantly lower mean IgG, IgA and IgM levels and the response to meningovaccine was also lower than in normal children.
Endotoxaemia and endotoxin-induced changes were sought in Nigerian patients presenting with cholera/diarrhoea. The organism was Vibrio cholerae, bio-type El Tor, serotype Hikojima. The limulus amoebocyte lysate gelation test was used qualitatively by the clot method, whilst a spectrophotometric method was used quantitatively to measure endotoxin levels. 25 acutely ill patients tested had detectable endotoxaemia by the Escherichia coli endotoxin standard. The highest endotoxin level was found in a patient with sub-conjunctival haemorrhage. Changes in platelet counts, the detection of complement breakdown product C3d in plasma, the elevation of fibrin degradation products, the finding of elevated, normal or depressed C3 levels and the absence of circulating immune complexes, suggest a pathogenic role for endotoxin in Vibrio cholerae El Tor diarrhoea.
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