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Neutralizing antibodies against poliovirus serotypes among children in southwest Nigeria
(Oxford University Press, 2005) Adewumi, M. O.; Donbraye, E.; Odaibo, G. N.; Bakarey, A. S.; Opaleye, O. O.; Olaleye, D. O.
In May 1988, the World Health Assembly resolved to eradicate poliomyelitis globally by the year 2000. Despite the reported success in national immunization days, acute flaccid paralysis surveillance and accelerated efforts to meet the deadline including ‘mopping-up’ were executed in 1999 and subsequent years. Nigeria remains one of the major reservoirs for wild poliovirus transmission. Neutralizing antibody titre to the three poliovirus serotypes was determined among children from different communities in southwest of Nigeria, and analysed by age, gender and location. About 0.5–2 ml of blood sample was collected by venepuncture from each child. Aliquot of serum from each blood sample was inactivated prior to neutralization test by the beta method for poliovirus antibodies. A total of 347 (59.6 per cent) out of 500 and 82 children enrolled for the study had at least antibody titre of 1:8 against each of the three poliovirus serotypes. Immunity level to the three poliovirus serotypes increased with age and peaked in children aged 4–6 years. Seven (53.8 per cent) out of 13 unvaccinated children tested in the study had detectable neutralizing antibody to the three serotypes. Immunity pattern of P2 > P1 and P3 was observed but no correlation between gender and antibody to the poliovirus serotypes. The populations had 59.6 per cent herd immunity for the three poliovirus serotypes. In a country with high incidence of poliomyelitis this situation leaves a high number of non-immunized children at the risk of infection with one or more poliovirus serotypes.
Prevalence of measles neutralizing antibody in children under 15 years in southwestern Nigeria
(2005) Opaleye, O. O.; Adewumi, M. O.; Donbraye, E.; Bakarey, A. S.; Odaibo, G. N.; Olaleye, O. D.
The immune status of children under 15 years in the Southwestern region of Nigeria against measles virus was determined using the neutralization test with a view to assessing the herd immunity to the virus in these communities. A total of 256 serum samples collected from children were tested by the beta method of neutralization. Forty (15.6%) of these samples were found to be positive at a titre of 1:256, 35 (13.7%) at 1:128, 36(14.1%) at 1:64, 37(14.5%) at 1:32, 38 (14.8%) at 1:16, 27 (10.5%) at 1:8 and 16 (6.3%) at 1:4. Twenty-seven (10.5%) of the 256 samples had no detectable antibody to the measles virus. There was no significant relationship between the antibody titre to measles virus and the gender of the children (p > 0.05). Also, there was no significant difference using Chi square analysis between the neutralizing antibody titres and the age of the children (p > 0.05). All the children whose samples were tested were vaccinated against measles as attested to by their parents. However, the vaccination does not seem to protect all the children, for some of them had no detectable neutralizing antibody while some had low neutralizing antibody titre. In Nigeria, where only a single dose of measles vaccine is given at 9 month, measles may remain a serious threat to the children population with its attendant high morbidity and mortality.
Reliability of testing and potential impact on HIV prevention in Nigeria
(2006) Odaibo, G. N.; Donbraye, E.; Adewumi, M. O.; Bakaery, A. S.; Ibeh, M. A.; Olaleye, D. O.
Several factors including variability of human immunodeficiency virus (HIV), laboratory facilities, cost and competence of personnel handling the tests are some of the important factors that affect accuracy and reliability of HIV testing in most parts of Africa. Recently investigators in Africa have observed that antibody detection assays based on antigens derived from HIV-1 subtype B show moderate to significantly lower sensitivity for detection of infection by various non-B subtypes. In this study, we evaluated the reliability of two EIA and 12 rapid HIV-1/2 test kits that are commercially available in Nigeria using the Western immunoblotting technique as reference. A panel of 100 sera from Western blot confirmed symptomatic or asymptomatic HIV-1 infected persons and 90 seronegative patients from those referred for testing in our laboratory were used for this study. Each sample was tested with two HIV-1/2 EIA, and 12 HIV-1/2 rapid test kits commercially available at one time or the other for HIV-1/2 testing in Nigeria. Overall, the sensitivity of the two EIA kits were 100% and 91.0% with specificity of 96.7% and 91.1% respectively. The sensitivity of the rapid test kits ranged from 88% to 98.0% with specificity of 92.2% to 100%. Further analysis showed significant variation in the sensitivity and specificity of the same kit based on whether an individual had asymptomatic or symptomatic infection The results of this study highlight the problem of diagnosis of HIV infections in Africa. It shows that the sensitivity of most of the rapid assays shall not be adequate for detection of early infection. The implications of possible misdiagnosis on the various intervention strategies that rely predominantly on correct HIV status of an individual are enormous. Thus, there is an urgent need for review of the current HIV testing assays or algorithms in Nigeria and other parts of Africa.