Molecular detection of SARS-CoV-2 infection in three geo-political zones of Nigeria: a cross-sectional study

Introduction

sequel to the emergence of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and its subsequent spread to all continents of the world, humans have continued to experience severe devastation to their health and economies. To control the spread of this virus, it is important to detect the infection in recently infected and asymptomatic individuals who are capable of infecting others. This study was designed to detect ongoing SARS-CoV-2 Infection among asymptomatic individuals in open markets across three geopolitical zones in Nigeria.

Methods

nasal and oropharyngeal swab samples were collected from 2,158 study participants between December 20^th, 2020 and March 20^th, 2021 from large open markets across three geo-political zones (Southwest, Northwest and Southeast) of Nigeria. Virus RNA was extracted from these swab samples and real time reverse transcription polymerase chain reaction (RT-PCR) was carried out for the detection of SARS-CoV-2 specific genes. Data were analysed using descriptive statistics.

Results

a total of 163 (7.6%) of the 2,158 participants enrolled for the study tested positive for SARS-CoV-2 by RT-PCR. The rate of infection was significantly higher in the North-western States of the country when compared to the western and Eastern regions (P=0.000). Similarly, the rate of infection was higher among buyers than sellers (P=0.000) and among males when compared with females, though the difference was not significant (p=0.31).

Conclusion

this study shows that there is a continuous spread of SARS-CoV-2, especially among active, asymptomatic individuals across many States in the country. There is therefore need to continuously educate citizens on the need to adhere to both the non-pharmaceutical and pharmaceutical preventive measures to protect themselves and ultimately curb the spread of the virus.

Epidemiology of Group A Rotavirus Diarrhea among Children Hospitalized for Acute Gastroenteritis in Ondo State, Nigeria

Globally, infective group A rotavirus (RVA) enteric infection in children culminates in acute diarrheal disease, severe dehydration, and mortality in children under the age of 5 years, particularly in sub-Saharan Africa. This research sought to determine the prevalence of RVA diarrhea among children aged below 5 years in Ondo state, as one of the necessary frameworks before instituting a vaccine campaign, and to expand knowledge on the epidemiology of RVA diarrhea in Nigeria.

In a cross-sectional descriptive study between October 2012 and September 2014, convenience sampling was adopted to obtain demographic information, clinical details, and stool samples from accented under five children who sought treatment for acute gastroenteritis at designated hospitals in Akure and Owo, Nigeria. A total of 390 stool samples were collected from children with acute diarrhea and tested for VP6 RVA antigen using enzyme immunoassay. Data generated were analyzed using descriptive statistics and chi-square at α 0.05.

From the 390 children hospitalized for diarrhea, 240 samples (240/390; 61.5%) were from males, while 150 samples (150/390; 38.5%) were from females, representing a male:female ratio of 1.6:1. RVAs were found in 24.2% (58/240) males and 28% (42/150) females, giving a male-female ratio of 1:1.2 and total prevalence of 25.6% (100/390). RVA infection was inversely proportional to the age as a rate of 11.8% was observed in children aged above 36 months and 31.8% (35/110) in children 7 to 12 months, while the highest rate (45.7%) was among children ≤ 6 months old. No significant difference was found (chi-square = 0.712) in the induction of diarrhea in children from Akure and Owo, neither was there any significant difference in the rates of infection between the boys and girls in Akure (chi-square = 0.576) nor in Owo (chi-square = 0.333). Seasonal association (chi-square = 5.802) in RVA infection was observed in the rainy season of year 2013/2014 period.

RVA diarrhea occurred year-round at a prevalence of 25.6%, predominantly in females. A seasonal fluctuation was observed in the rainy and dry seasons of the 2-year period. RVA diarrhea occurred predominantly in children aged below 18 months of age, and may thus help in determining the optimal period/schedule of any immunization program.

Virological investigation of fatal rabies in a minor bitten by a mongrel in Nigeria

Rabies is a deadly viral disease transmitted through bites of infected animals. Outbreaks continue to escalate in Africa, with fatalities in humans, especially in rural areas, but are rarely reported. About 40% casualties occur among children of < 15 years. A 5-year-old boy on referral from a Primary Health Care Centre to a tertiary hospital presented with anxiety, confusion, agitation, hydrophobia, photo-phobia and aero-phobia, seven weeks after he was bitten by a stray dog in a rural community in Nigeria. The patient did not receive post-exposure prophylaxis and died 48 hours post admission. Confirmatory diagnosis was rabies and the phylogenetic analysis of the partial N-gene sequence of the virus localized it to Africa 2 (genotype 1) Lyssaviruses. There was 95.7-100% and 94.9-99.5% identity between the isolate and other genotype 1 Lyssaviruses and 100% homology with rabies viruses from Mali, Burkina Faso, Senegal and Central African Republic.

Adherence to Medication among Patients with Chronic Hepatitis B Infection Attending a Tertiary Hospital in South Western Nigeria

INTRODUCTION

Chronic hepatitis B (CHB) is an international public health problem. Treatment reduces its morbidity, mortality and infectivity. The aim of this study was to determine adherence among CHB infected patients on Tenofovir and the reasons for non-adherence.

METHODOLOGY

It was a cross-sectional study of patients on tenofovir for at least 6 months. Information was obtained on bio- data, adherence to tenofovir, duration and reasons for nonadherence using an interviewer administered questionnaire. Non- adherence was defined as patient reporting missing medication at all. Chi square or Fisher exact test and Student's t-test were used to determine associations. P value less than 0.05 was considered significant.

RESULTS

A total of 150 participants comprising of 76 (50.7%) females and 74 (49.3%) males with mean age of 39.2 ± 11.4 years, participated in the study. Non adherence rate was 65%. There was no significant association between non-adherence and tribe (p=0.7), level of education (p=0.8), religion (p=0.2), sex (p=0.9), clinical state (p=0.8), treatment experience (p=0.8) and months on Tenofovir (0.1) while a significant association existed with age (0.01), the presence of comorbidity (p=0.02) and taking another medication apart from tenfovir (0.00). The reasons for non-adherence included out of station 22 (14.7%), financial constraint 19(12.5%), unavailability of the drug 19 (12.5%), forgetfulness 15 (10%), perceived side effects 12 (8%), undetectable serum DNA quantification 11 (7.3%), ignorance of continuous use of Tenofovir 10 (6.7%), and pregnancy 9 (6%) among others.

CONCLUSION

Adherence to Tenofovir is poor among CHB patients attending University College Hospital, Ibadan.

Molecular characterization of canine parvovirus from domestic dogs in Nigeria: Introduction and spread of a CPV-2c mutant and replacement of older CPV-2a by the "new CPV-2a" strain

Canine parvovirus (CPV) is a contagious and highly pathogenic virus of dogs. After its first report in 1978, the CPV original type (CPV-2) was rapidly and totally replaced by three antigenic variants named CPV-2a, CPV-2b and CPV-2c that circulate in various countries at different frequencies and recently reported in Nigeria. This study describes the molecular characterization of 28 CPV strains in dogs presenting with gastroenteritis in veterinary clinics at Lagos and Ibadan, Nigeria. The results show the predominance (92.8%) of CPV-2a, while CPV-2c was found only in two samples. Phylogenetic analyses revealed that the CPV Nigerian strains were closely related to Asian strains and 26 CPV-2a out of 28 CPV sequences fell into 2 different subclades consistent with predicted amino acid mutations at position 267, 321, 324 and 440. Lys321Asn was evident in all the Nigerian strains whilst Phe267Tyr and Tyr324Ile were observed in 96.4% of the sequences, respectively. Thr440Ala occurred in 89.3% of sequences from this study. The new CPV-2a was predominant and appears to have replaced other CPV-2a strains in South-western Nigeria whilst the CPV-2c strain which is identical to the isolate recently reported in Northern Nigeria, may have been introduced in this country at the time of this study. Monitoring virus epidemiology is important to better understand the dynamics of CPV evolution and the eventual need to change or improve existing vaccination strategies.

Complete genome sequencing of H1N1pdm09 swine influenza isolates from Nigeria reveals likely reverse zoonotic transmission at the human-animal interface in intensive piggery

Prevailing agro-ecological conditions and intermingling of human and animals in intensive farms in urban and peri-urban areas in Africa favour cross species transmission of pathogens at the human-animal interface. However, molecular epidemiology studies of zoonotic swine influenza viruses in this region are limited. In this study, isolates of pandemic influenza virus (H1N1pdm09) obtained from pigs in Nigeria were fully sequenced. BLAST of swine influenza virus genes from Nigeria was carried out in GenBank and gene alignment was done using MEGA version 7. Maximum likelihood method (PhyML program) was used to determine gene evolutionary relationships with other viruses and phylogenetic trees were constructed to infer genomic clusters and relationship. Swine influenza viruses isolated and sequenced in this study were monophyletic and 99% congenetic with human isolates from Nigeria, Cameroon, Ghana and USA suggesting reverse zoonotic transmission from humans to pigs in intensive husbandry. A Q240R and S31N substitution among others were detected in the haemagglutinin and matrix genes, respectively, indicating potentials for mutations during interspecies co-mingling and transmission. The A/H1N1pdm09 viruses circulating in pigs that are also exposed to avian influenza in the same epidemiological zones could engender emergence of novel viruses with zoonotic or pandemic potential requiring enhanced surveillance and monitoring.

Serological evidence of Rift Valley fever virus infection in slaughtered ruminants in Nigeria

The risk of exposure of slaughterhouse workers to Rift Valley fever (RVF) virus-infected animals in Nigeria was assessed by determining the prevalence of anti-RVF IgM in cattle, goats and sheep slaughtered in a major abattoir in Ibadan, Nigeria. Blood samples were collected from 290 animals in Bodija Municipal abattoir, Ibadan, Nigeria in January and February 2017 and analyzed for the presence of RVF virus using IgM Enzyme-Linked Immunosorbent Assay (ELISA) and Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) for detection of the virus RNA. Descriptive statistics was used to analyze data. Overall, an IgM prevalence of 0.7% (2/290) was found among the blood samples of the animals, suggesting recent exposure to the virus. Antibody was detected in the sera from a cow and one goat. RVF virus RNA was not detected in the 2 IgM positive blood samples. There was no statistically significant relationship between RVF IgM infection and some variables of the animals, including age, sex and breed (p ≥ 0.05). Results of this study indicate active RVF virus transmission in domestic livestock in Nigeria. The study emphasizes the need to embark on monitoring of human and animal populations to prevent outbreak of the virus in the country.

High rate of Hepatitis B virus infection among hairdressers in Ibadan, Nigeria

Hepatitis B virus (HBV) infection is a major public health problem for over two billion people infected globally. Occupationally exposed persons are at high risk of HBV infection and, apart from medical personnel, there is dearth of information concerning the prevalence and awareness of HBV among this population in Nigeria. This study was designed to determine the levels of HBV awareness and prevalence of HBV infection among hairdressers in Ibadan, Nigeria. Hairdressers and teachers (unmatched controls) in four local government areas in Ibadan were tested for HBV infection using ELISA technique. Dried blood spot (DBS) samples were collected from 171 participants. DBS elutes from the samples were tested for HBV surface antigen (HBsAg). The rate of HBV infection was higher (p = 0.005) among the hairdressers (13.0%) than teachers (4.8%). However, teachers were better informed about HBV (38%) compared to hairdressers (13%; p = 0.0001). Differences in HBV awareness and occupation type were found to be significant (P = 0.001). Hairdressers are at high risk of HBV infection and may constitute a major source of HBV spread among urban dwellers, especially in areas where awareness is low. Routine HBV screening and appropriate interventions for hairdressers are recommended to interrupt HBV transmission.

Is there any relationship between hearing threshold levels and CD4 cell count of human immunodeficiency virus infected adults?

Background The role of viral load level and/or CD4 (Cluster of differentiation 4) cell count in the aetiopathogenesis of hearing loss in HIV infection is unclear. Therefore, we investigated the relationship between CD4 cell counts, viral load and hearing threshold of HIV (Human immunodeficiency virus) infected adults.

METHODS

This cohort audiometric study involved consecutive HIV-infected and HIV-uninfected adults as controls. Clinical data relating to hearing loss, HIV status, and highly -active antiretroviral therapy (HAART) were obtained. Audiornetric evaluation was performed. The most recent CD4 cell counts and RNA viral load-of HIV-infected participants were obtained from clinic records.

RESULTS

There were 299(66.7%) HIV-infected adults and 149(33.3%) controls with mean age of 39.64± 12.45 years and 39.60±12.45 years respectively (p=0.98). In both groups, there were more participants with left hearing loss. Mild to profound hearing loss was found in 65.9% HIV- infected participants and 53.7% controls. Majority (86.3%) of the HIV-infected participants were on HAART. The mean CD4 cell count was 654.58±289.15 in 41 HIV-infected participants not on HAART and 523.95±300.17 in 258 participants on HAART (p=0.01). Majority,- 197 (62%) HIV- infected participants with hearing loss had CD4 cell count ≤200 cells/mm3. Higher viral load significantly correlated with low CD4 cell counts (p<0.0 1; r=0. 18) and low CD4 cell count significantly correlated with high hearing threshold (p<O.01; r=0. 17).

CONCLUSION

There was a trend towards more hearing loss among the HIV-infected adults. The higher hearing threshold in those with low CD4 cell counts of <200 cells/mm3 suggests possible relationship between hearing status and severity of HIV disease.

Tissue culture isolation of lyssa viruses from apparently healthy unvaccinated dogs in Nigeria

BACKGROUND

There have been previous reports of inapparent infection and intermittent secretion of rabies virus in the saliva of apparently healthy dogs in some African countries, including Nigeria.

OBJECTIVE

The study was therefore aimed at examining the carrier status of rabies in apparently healthy Nigerian dogs in the settlement areas studied.

METHODS

Ninety-two swabs samples from oral mucosae of domestic dogs (mongrels) without vaccination history were assayed for lyssaviruses by tissue culture isolation test in Vero cells.

RESULTS

Rabies or rabies-related viruses were recovered from eighteen, representing 19.6% of the samples. The study showed that lyssaviruses were present in 4 out of the 6 settlements of the study areas. Among the areas where the viruses were present, the rate of isolation ranged from 11.1% to 66.7%. Female dogs had a little higher infection rate (12.0%) than their male counterparts (7.6%). Among age groups, the highest rate of infection (66.7%) was detected in dogs aged one to 3 years while the rate of 3.7% was found in dogs aged less than one year.

CONCLUSION

The results of this study agree with the carrier state of rabies in domestic dogs, the common reservoir hosts of its etiologic agents in Nigeria and the rest of Africa andAsia; this is a serious threat to humans in these settlements. Although the load of infective virus in saliva is lower than that in brain, saliva collection for rabies diagnosis is simple, safer, faster and cheaper. Thus we suggest that saliva samples could be used as an alternative to brain specimens for rabies virus antigen testing in dogs, especially, when it is not practicable to obtain brain specimen.

Detection and isolation of 2009 pandemic influenza A/H1N1 virus in commercial piggery, Lagos Nigeria

WHO declared pandemic of A/H1N1 influenza in 2009 following global spread of the newly emerged strain of the virus from swine. Presently there is a dearth of data on the ecology of pandemic influenza H1N1 required for planning of intervention measures in sub Saharan Africa. Herein we report isolation of 2009 pandemic influenza A/H1N1 in an intensive mega piggery farms operation in South West Nigeria. Sentinel surveillance was carried out in a cohort of intensively reared pigs over a period of two years. Nasal swab specimens were collected at monthly interval from observed clinical cases of influenza like illness in pigs and pig handlers. Samples were analyzed by real time RT-PCR and isolation in chicken embryonated eggs. A total of 227 clinical cases of influenza like illness were observed among pigs out of which 31 (13.7%) were positive for influenza A matrix gene by real time RT-PCR. Virus isolation yielded 29 (12%) isolates out of which 18 (18%) were identified as influenza A/H1N1 by Heamaglutination Inhibition test using H1 antisera. RT-PCR positive samples were subtyped as 2009 pandemic A/H1N1 with subtype specific primers and probes. This is the first report of detection and isolation of pandemic influenza H1N1 from pigs in Nigeria. Continuous circulation of this virus in pigs may cause reassortments with seasonal influenza or mutations and substitutions in the gene that may result in the emergence of novel or pandemic influenza virus of economic and public health importance. Nigeria is considered a geographical hotspot of zoonotic diseases, which necessitate active surveillance and monitoring of emerging pandemic threats.

HBV infectivity among Nigerians

The study involved 60 (non-immunized), 14 (immunized against HBV), healthy Nigerian adults and 28 Nigerian patients with hepatitis. Their sera were tested for HBsAg, HBeAg, anti-HBe, anti-HBc, anti-HBs and anti-HCV while only 15 subjects with chronic hepatitis had HBV DNA assay by PCR. The subjects aged 21 to 72 years and comprised 75 male and 27 female adults. The prevalence of HBV infection by HBsAg and/or anti-HBc sero-positivity was 55.9%. Only HBsAg and anti-HBs were detectable in 21% each among immunized while HBsAg, HBeAg, anti-HBe, anti-HBc, anti-HBs were present in 58%, 20%, 6%, 32%, and 42% respectively in the non-immunized subjects. HBV DNA was positive in 86.7% of the 15 subjects. About fifty five percent of all subjects were infectious of HBV with 13.7%, 3.9%. 32.3% and 4.9% accounting for high, medium, low and very low infectivity respectively while 44.1% and 1% of the subjects were susceptible and naturally immuned to HBV respectively. Coinfection with HCV tends to favour HBV infectivity. In conclusion, the infectivity of HBV among Nigeria is varied but high and a great proportion of the population is susceptible.

Are patients with primary hepatocellular carcinoma infectious of hepatitis B, C and D viruses?

Primary HepatoCellular Carcinoma (PHCC) has been strongly associated with HBV and HCV infections among other aetiological factors. However; do the patients still spread the viruses? This study involved forty one Nigerian adult patients with PHCC and 45 controls who were tested for HBsAg, HBeAg, Anti-HBe, Anti-HBs, anti-HCV IgM and IgG, anti-HDV and HDV antigen using ELISA. Statistical analysis was carried out with the student - t - test and Mc Nemar test at p < 0.05. The subjects consisted of male:female ratio of 3:1 for both the PHCC patients and controls. Evidence of exposure to hepatitis B, C and D viruses was detected in 95.1%, 44% and 0% of the patients respectively while the respective values of 24%, 11.1% and 0% were obtained for the controls. Indication for high (HBeAg) and low (anti HBe) HBV viral replication, and acute HBV infection were detected in 12.5%, 92.7% and 2.2% respectively among the patients while only 35.6% of the controls had low HBV viral replication. Acute and chronic infections of HCV were also found in 26.8% and 24.4% of the patients respectively compared to the respective values of 2.2% and 11.1% of the controls. Occult HBV infection occurred in equal proportions (11%) of both the patients (31.7%) and controls (35.6%). In conclusion, infectious HBV and HCV particles are present among Nigerian patients with PHCC while HDV infection is uncommon. Hence, safe medical care should be practised for all patients with PHCC while relatives should be screened for these viruses.

HIV-1 drug resistant mutations in chronically infected treatment naive individuals in the pre-ARV era in Nigeria

In Nigeria the Federal Government rolled out antiretroviral drugs for the management of HIV infection in year 2002. This study was carried out to determine the circulating antiviral drug mutations among ARV naïve patients with chronic HIV infection during the pre-ARV roll out era in the country. DNA was extracted from stored whole blood samples collected from 75 HIV positive patients attending the Medical outpatient clinic between December 1996 and November 2001. The Reverse transcriptase (RT) and the protease (PR) regions of the viral genome were amplified by nested PCR and then sequenced by cycle sequencing and analyzed using the ABI 3100 DNA sequencer to determine the mutations associated with protease inhibitors (PI), nucleoside reverse transcriptase inhibitors (NRTI) and non-nucleoside reverse transcriptase inhibitor (NNRTI). Ten of the 64 (15.6%) samples with positive PCR had mutations for PR inhibitors (PI) including R8D, I 15V, G16E, M36I, M46L, L63P and H69K, while 5 of 63 harbored RT inhibitor (NRTI/NNRTI); V179I, A98T, V179E and A98S. Detection ofARV drug resistant mutations when ARV was not known to be in use in Nigeria calls for caution in the interpretation of drug resistance profile of HIV-1 from infected persons on treatment ARVs in the country.

Genital ulcer diseases among HIV-infected female commercial sex workers in Ibadan, Nigeria

We evaluated the prevalence and association of Genital Ulcer Diseases (GUDs) among HIV-1 infected female commercial sex workers (FCSWs) in Ibadan, Nigeria. A total of 250 FCSWs from brothels in Ibadan were tested for presence of antibodies to HIV and Syphilis. Pelvic examinations for signs of sexually transmitted infections (STIs) were carried out on the subjects. Endocervical and high vaginal swabs were collected from each of the subjects to establish laboratory diagnosis of STIs. Their age ranged from 15 to 55 years (Mean = 25.8 yrs; SD = 3.74). Majority (246/250) were Nigerians, while 1.6% were from neighboring West African countries. Sixty four (25.6%) of the subjects were positive for HIV-1 while seven (2.8%) had dual HIV-1/2 infection. Analysis of the STIs showed that 49 (19.6%) of the CSWs had GUDs. Herpes genitalis was the commonest GUDs as it occurred in 25 (10%) of the subjects. Other STIs identified were chancroid (5.6%), syphilis (4.0%) and lymphogranuloma venerum (LGV) (4%). Sixteen (64.0%) of the CSWs with herpes genitalis had HIV-1 infection. The risk ratio of herpes genitalis for HIV acquisition was 3.0 (95% CI: 2.0 - 4.4). Syphilis and chancroid were also found tobe significantly associated with increased risk of HIV infection (p < 0.0001). The adjusted odd ratios for Herpes genitalis, chancroid, and syphilis were 3.7 (1-13.0, p < 0.05), 19.8 (2.7-13.0, p < 0.05) and 19.1 (1-231.0, p < 0.05) respectively. There is need to educate FCSWs continually to adopt safer sexual behaviours, seek early diagnosis and treatment of GUDs to reduce their risk of transmitting HIV infection.

Pregnancy outcome in the elderly primigravidae

We assessed the effect of advancing maternal age ( 35 years) on the outcome of pregnancy in first births among 50 elderly primigravidae compared with a control group of 50 younger primigravidae (20-29 years) at the University College Hospital Ibadan from 1 January 1988 to 31 December 1992. Most of the elderly primigravidae were professionals and the majority of them (68%) had involuntary infertility. Frequent hospital admissions, preterm delivery, low birth weights and very high caesarean section rates were the major problems highlighted in the elderly primigravidae, while anaemia was more frequent in the younger primigravidae. Unnecessary caesarean sections on the excuse of 'precious' baby in the elderly primigravidae should be discouraged bearing in mind its medico-social implications. It is concluded that although the elderly primigravidae may have higher rates of complications of pregnancy, delivery and neonatal deaths their overall risk of referral to special care baby unit is not appreciably increased.

Risk of hepatitis B virus in the slaughter house

The study involved 180 Nigerian butchers and 180 traders (controls) selected by multistage stratified sampling who had their sera assayed for HBsAg (hepatitis B surface antigen) by enzyme-linked immunosorbent assay method. The butchers and the controls had an HBsAg sero-prevalence rate of 9.4% and 3.3%, respectively. Various risky practices were more common among the butchers but their hepatitis B antigenaemia was not related to the duration of their occupational exposure. The study shows that the butchers constitute a high risk occupation for hepatitis B viral infection.

Detection of HIV antigen and cDNA among antibody-negative blood samples in Nigeria

In developing countries as many as 50% of patients for whom a transfusion is indicated are at risk of dying immediately if transfusion is withheld. It is therefore important that blood transfusion is made as safe as possible. This study was designed to assess the safety of blood transfusion in two large blood banks in Ibadan, Nigeria. Aliquots of 250 samples already screened and passed as negative for HIV-1 and -2 were collected from each of the blood banks. Samples were tested for the presence of HIV-1 antigen (ELAVIA Ag I) and the antigen-positive samples tested for the presence of specific HIV-1 antibodies by Western blot (BioRad, France). All antigen-positive samples were also subjected to PCR. HIV-1 antigen was detected in 6 (1.2%) of the 500 samples, of which 4 (0.8%) and 3 (0.6%) were Western blot-indeterminate and PCR-positive, respectively. Transfusion of HIV-contaminated blood may be contributing significantly to the spread of the virus in Nigeria. There is therefore an urgent need for an organized blood-banking system with facilities for more sensitive assays for the detection of HIV in blood to prevent transmission through transfusion.

Nigerian butchers and hepatitis B virus infection

Various target groups have been identified in Nigeria for studying the prevalence of hepatitis B virus infection; however there is no information on its prevalence among workers in slaughter houses. This study determined the seroprevalence of hepatitis B virus infection in Nigerian butchers at Ibadan, and comprised 360 healthy Nigerian adult subjects (180 butchers, 180 traders as controls) selected by multistage stratified sampling. A questionnaire was used to collect relevant information and included points about risk behaviour. ELISA was used to detect the hepatitis B surface antigen in the serum; the seroprevalence rate in butchers and controls was 9.4% and 3.3%, respectively (p<0.05). Risk behaviour was seen more commonly in butchers than in controls. The presence of hepatitis B surface antigen in the serum was not related to the duration of occupational exposure or the number of partners. In summary, butchers comprise a high-risk occupational group for exposure to hepatitis B virus infection. We conclude that routine screening for parenterally acquired infections in this group is thus necessary in order to identify those who will require treatment and immunisation, especially against hepatitis B virus infection.

HIV infection among patients with pulmonary tuberculosis in Nigeria

Respiratory problems like Pneumocystic carinni and Pulmonary tuberculosis (PTB) are among the common opportunistic infections in patients with HIV/AIDS. The risk of acquiring Mycobacterium tuberculosis in a community becomes greater with increase in the number of HIV positive persons with active tuberculosis. This study was carried out to determine the magnitude of HIV infection among PTB patients in different parts of Nigeria as part of the year 2000 national HIV surveillance programme. Blood samples were collected on blotting paper from a total of 2826 individuals attending TB clinics between 1st of September and 1st November, 2000. Samples were collected from patients with confirmed PTB from 12 states in the 6 geopolitical/health zone (2 states/zone) of Nigeria as part of high risk sentinel population groups. Samples were tested for the presence of HIV antibodies using commercial ELISA (Genescreen HIV-1/2, Sanofi Pasteur, Paris). All initially reactive samples were retested with a rapid EIA (Gene II, Sanofi Pasteur, Paris) according to the WHO recommendations (option II). HIV Prevalence in the states varied from 4.2% in Oyo to 35.1% in Benue States with a median prevalence of 17.0%. HIV Prevalence increased with age to a peak of 23.9% among PTB patients 30-39 years and then declined progressively to 12.8% among those 60 years and above. A relatively high HIV infection rate (13.8%) was found among the young adolescent age group 10-19 years. There was no significant difference in the rate among male and female PTB patients tested. Comparison with results of previous HIV sero-surveys shows a steady increase in HIV prevalence among PTB patients over the years. The high prevalence of HIV among young PTB patients aged 10-19 years in this study is worrisome and must be noted for intervention.

Reliability of testing and potential impact on HIV prevention in Nigeria

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.

Mother-to-child transmission of different HIV-1 subtypes among ARV Naïve infected pregnant women in Nigeria

The rate of mother-to-child transmission (MTCT) of HIV as well as the implications of the circulating multiple subtypes to MTCT in Nigeria are not known. This study was therefore undertaken to determine the differential rates of MTCT of HIV-1 subtypes detected among infected pregnant women before ARV intervention therapy became available in Nigeria. Twenty of the HIV-positive women who signed the informed consent form during pregnancy brought their babies for follow-up testing at age 18-24 months. Plasma samples from both mother and baby were tested for HIV antibody at the Department of Virology, UCH, Ibadan, Nigeria. All positive samples (plasma and peripheral blood mononuclear cells-PBMCs) were shipped to the Institute of Tropical Medicine, Antwerp, Belgium, where the subtype of the infecting virus was determined using the HMA technique. Overall, a mother-to-child HIV transmission rate of 45% was found in this cohort. Specifically, 36.4%, 66.7% and 100% of the women infected with HIV-1 CRF02 (IbNg), G and B, respectively, transmitted the virus to their babies. As far as it can be ascertained, this is the first report on the rate of MTCT of HIV in Nigeria. The findings reported in this paper will form a useful reference for assessment of currently available therapeutic intervention of MTCT in the country.

Neutralizing antibodies against poliovirus serotypes among children in southwest Nigeria

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.

The problems of indeterminate HIV results in blood transfusion services in Nigeria

Five hundred sera samples were collected from individuals whose age range was 16-40 years, analysed using Murex 1 and 2 and Capillus HIV kit (Cambridge Biotechnology, Cambridge, UK), and confirmed with Western Blot technique (Biorad). Of these, 186 (37.2%) were repeatedly reactive, 90 (48.4%) were confirmed positive, 55 (29.6%) indeterminate (20 [10.7%] from blood donors) and 44 (22.0%) were negative. The data reveal a significant correlation between indeterminate results and confirmed positive sera (P < 0.05). This demonstrates the high incidence of indeterminate HIV results encountered in blood transfusion services.

Vaginal delivery after one caesarean section in Nigerian women

A total of 120 Nigerian women at term pregnancy with one previous caesarean delivery were studied between June 1988 and May 1993. Elective caesarean section was performed in 3 (2.5%). Vaginal delivery was achieved in 101 (86.5%) of those allowed a trial of labour. Intrapartum caesarean section was done in 16 (13.7%) cases. Rupture of the uterus occurred in 3 cases (2.6%) with perinatal loss of 2 babies. There was no maternal mortality. There was no significant correlation between vaginal delivery and birth weight, gestational age or initial indication for the primary caesarean section. It is concluded that trial of labour is safe after a previous caesarean section in selected patients.

Phylogenetic analysis of new hepatitis B virus isolates from Nigeria supports endemicity of genotype E in West Africa

Isolates of hepatitis B viruses were collected from 20 acute and chronic hepatitis patients in a highly endemic region of Nigeria. Sequencing classified the isolates to the ayw4, as they all contained the amino acid variations characteristic for that serotype. In the pre-S2 region of five isolates, three to seven amino acids were deleted, suggesting that immune escape mutations previously associated only with chronic HBV infection may be observed also in acute disease. Phylogenetic analysis of the complete pre-S2/S (large S) genes (831 nt) demonstrated that all the viruses belonged to the same genotype E. So far, no isolates of genotype E have been found in any other region of the world, including the Americas. This may suggest a relatively recent introduction of this genotype into humans and would explain the relatively low genetic diversity of viruses belonging to this genotype. One genotype E virus had been found previously in a chimpanzee, and viruses belonging to the CHIMP genotype are related to other genotype E viruses. These findings are compatible with a transmission of genotype E viruses from chimpanzees to humans.

Human immunodeficiency seropositivity among mother-child pairs in South West Nigeria: a community-based survey

A community based survey to determine the prevalence of human immunodeficiency infection in Nigerian women and children in South Western Nigeria is reported. A multi-stage cluster random sampling procedure was used to select mother-child pairs from 35 enumeration areas in South western Nigeria. The final study sample consisted of 460 mothers and 476 children (including 16 sets of twins). A commercially available recombinant antigen-based ELISA method was used to test for HIV-1 and HIV-2 antibody in sera and Western blotting was used as a confirmatory test for initially reactive samples. Only one mother-child pair (out of 460 mother-child pairs) was found to be positive for HIV antibody giving a mother-child concordance for HIV infection of 0.22%. Antibody to either HIV-1 or HIV-2 was detected in 3.8% (18/476) of the children's sera and in 43% (20/460) of mothers sera. HIV-1 reactivity was commoner than HIV-2 reactivity (2.9% versus 0.8% among children and 2.8% versus 1.5% among mothers). There were many more positive samples in the rural than in urban areas among children (7.1% versus 1.1%) and also among mothers (6.8% versus 2.4%), (p<0.001). Thus, HIV infection appears to be a real problem in South western Nigeria. The lack of concordance between mother-child sera suggests that vertical transmission may not be a major route of transmission of HIV infection in children in South western Nigeria. It is suggested that certain high risk practices (such as the re-use of unsterilised hypodermic needles for injections and surgical knives in local scarification) which are common practices, especially in rural areas, need to be investigated as potential major modes of transmission of the infection. Control programmes need to take note of these findings in order to adequately plan comprehensive health education which will cover the whole population, including children.

Antibodies to Lassa virus Z protein and nucleoprotein co-occur in human sera from Lassa fever endemic regions

It is not known whether the small 11-kDa Z protein of Lassa virus is immunogenic during human Lassa virus infection. To obtain evidence for the existence of an antibody response and to test the suitability of these antibodies for serosurveys, sera from Lassa fever endemic regions (Guinea and Nigeria, n = 75) were tested for co-reactivity to Z protein and nucleoprotein (NP). Sera from a non-endemic region (Uganda, n = 50) served as a specificity control. Z protein and NP were expressed in Escherichia coli, affinity-purified, and used as antigen in Western blot. Indirect immunofluorescence (IIF) with Lassa virus-infected cells was performed for comparison. Due to high unspecific reactivity of the African sera, Western blot testing was performed with a 1:1,000 serum dilution. Under these conditions, none of the control sera but 12% of the sera from endemic regions co-reacted with both Z protein and NP. Reactivity to Z protein was significantly associated with NP reactivity (P < 10(-6)). NP and Z protein-specific antibodies were co-detected in 33% of the IIF-positive sera and in 5% of the IIF-negative sera (P = 0.001). These data provide evidence for appearance of antibodies to Z protein and NP following Lassa virus infection. A recombinant blot for detection of both antibody specificities seems to be specific but less sensitive than IIF.

An outbreak of African Swine Fever in Nigeria: virus isolation and molecular characterization of the VP72 gene of a first isolate from West Africa

The isolation of 98/ASF/NG, a strain of African Swine Fever Virus (ASFV) associated with a 1998 epizootic in Nigeria, is reported. This first isolate of the virus from West Africa was identified through a successful polymerase chain reaction (PCR) amplification and sequencing of a 280 base pair (bp) fragment of the Major Capsid Protein (VP72) gene. Further amplification and sequence analysis of a 1.9 kilobase pair (kbp) fragment encompassing the complete VP72 gene showed that the isolate has a 92.2%, 92.4%, and 97.2% homology with previously sequenced Ugandan, Dominican Republican and Spanish isolates respectively. Of the 50 nucleotide changes observed in this highly conserved gene, 45 were found to result in 40 amino acid changes clustered around the central region (position 426 to 516) of the VP 72 protein while changes at the remaining 5 positions were silent. These changes also led to the loss of two out of the seven potential N-glycosylation sites which are in this gene conserved among all isolates. The possible epizootiological implications of such mutations in a highly conserved gene of a DNA virus is discussed in relation to this outbreak.

Human T-cell lymphotropic virus types I and II infections in mother-child pairs in Nigeria

A community-based survey to determine the prevalence of human T-cell lymphotropic type I (HTLV-I) and type II (HTLV-II) virus infections in mothers and children in south-western Nigeria was carried out using blood samples collected in 1993. A multistage cluster, random sampling procedure was used to select 460 mother-child pairs (476 children because there were 16 sets of twins) from 14 enumeration areas. A commercially available, whole HTLV-I lysate antigen-based ELISA method was used to screen for HTLV-I and HTLV-II antibodies in the samples. A synthetic peptide antigen-based ELISA was then used to differentiate between antibody reactivity to either HTLV-I or HTLV-II. Reactivity to HTLV-I or HTLV-II antibodies was found in 4.3 per cent (20/460) of mothers and in 1.1 per cent (5/476) of children in both rural and urban communities and all the positive children were males. None of the 16 sets of twins in this study was positive for either HTLV-I or HTLV-II. Also none of the mother-child paired sera tested showed concordance for either HTLV-I or HTLV-II antibody positivity. The lack of concordance between mother and child sera suggests that vertical transmission may not be the major route of transmission of HTLV infection to children in south-western Nigeria. Other modes of transmission, such as the re-use of unsterilized needles for injections and surgical knives in local scarification, which are common practices in the region, need to be investigated as they may prove to be more important than vertical transmission. These findings have important implications for any control programme for diseases that can be spread by the same routes as HTLV infection (the human immunodeficiency viruses, hepatitis B, and hepatitis C infections).

Stability of 17D yellow fever virus vaccine using different stabilizers

To optimize the thermostability of lyophilized 17D vaccine, the authors investigated parameters important for the freeze-drying process. Six different stabilizers with different sugars and amino acids were analysed in a freeze-thaw cycle for their crystallization characteristics and their stabilizing effect under thermal treatment conditions of 37 degrees C for 28 days. This test indicated that three out of six stabilizers (B, C, F) kept the vaccine significantly more stable than the three others (A, D, E). Under storing conditions of 4 degrees C over 96 days stabilizers A, B and C produced the lowest decrease in titre of about 10% in contrast to stabilizers D, E and F with a higher decrease in infectivity titre. Analysing the stability of the 17D vaccine using five different reconstitution solutions, we found that 90% D2O shows the best stabilizing effect under thermal treatment of 37 degrees C up to 24 h.

Isolation and characterization of a new subtype A variant of human immunodeficiency virus type I from Nigeria

We have isolated a new variant of HIV-1 from Nigeria, Africa. The virus was recovered from the peripheral blood mononuclear cells (PBMCs) of an apparently healthy 23-year-old male from Ibadan, Nigeria. The in vitro studies indicated that the virus was highly cytopathic and replicated well in normal PBMCs, established T-cell lines and the monocytic cell line U937. The highest replicative titre of the virus was obtained in freshly isolated primary macrophage/monocyte cells which also showed the least cytopathology. Most other cultures showed single-cell cytolysis and giant cells, and syncytia were not induced in the HTLV-1 infected MT-2 cells. Since no HIV strain has been isolated from Nigeria, we obtained cDNA clones containing the env gene, to further characterize the Nigerian virus. Based on the DNA sequence analysis of 14 clones containing the coding region for its gp 120 protein, the Nigerian HIV isolate has been classified as HIV-1 subtype A. Only one subtype A virus from Rwanda has been characterized and this virus has not been shown to exhibit extreme cytopathicity in various cell types as was observed with the Nigerian strain. Further, the ability of this virus to grow well in lymphocytes, monocytes and macrophages and to exhibit cytopathicity without causing syncytia are uncommon properties distinguishing the Nigerian virus from other HIV-1 strains. Since most macrophage-tropic viruses have been associated with 'neurotropism', the isolation of an HIV-1 strain from the blood of an individual with no known neurological disorder indicates that this rapidly replicating cytopathic virus, with a broad host range, may play an important role in the pathogenesis of HIV disease. This represents the first report of an HIV-1 isolate from Nigeria.

Evidence of serological cross-reactivities with human immunodeficiency virus types 1 and 2 and human T-lymphotropic virus types I and II in sera of pregnant women in Ibadan, Nigeria

BACKGROUND

Our previous studies have indicated that the human immunodeficiency virus (HIV) and human T-lymphotropic virus (HTLV) groups of retroviruses are endemic among various populations in Nigeria. These viruses are antigenically distinct and antibodies to HIV and HTLV do not cross-react, so we studied the prevalence of HIV-1, HIV-2, HTLV-I and HTLV-II antibodies in sera of pregnant women attending an antenatal clinic in Ibadan, Nigeria.

METHODS

In all, 364 sera were screened using three different enzyme immunoassays, including those that distinguished HIV-1 antibodies from HIV-2, and HTLV-I antibodies from HTLV-II. All repeatedly reactive sera were confirmed by Western blots and synthetic peptide assays for the respective viruses.

RESULTS

Overall, 71 sera (19.5%) had antibodies to HIV, HTLV or both groups of retroviruses. Most (95.8%) of the reactive samples were from women 20-29 years old. Two of five sera from individuals < 20 years old reacted for HIV antibodies while one serum from a 40 year old woman was reactive for HTLV-I antibodies. Of the 71 reactive sera, 29 (8%) had antibodies to HIV (HIV-1 = 14, HIV-2 = 9, HIV-1/2 = 6) and 42 samples (11.5%) showed antibodies to HTLV (HTLV-I = 20, HTLV-II = 14, HTLV-I/II = 8). Seven of 71 seropositive samples (9.8%) reacted for both HIV and HTLV antibodies in various combinations, including one serum that showed antibody reactivities to all four retroviruses (i.e. HIV-1, HIV-2, HTLV-I and HTLV-II).

CONCLUSIONS

The high prevalence of antibodies to subtypes of the two entirely distinct retrovirus groups in young women has important implications for defining epidemiological patterns of diseases associated with co-infections with two or more retroviruses.

Type-specific immune response to human T cell lymphotropic virus (HTLV) type I and type II infections in Nigeria

Type-specific antibody responses to human T cell lymphotropic virus type I (HTLV-I) and type II (HTLV-II) were studied in blood samples collected from 25 different locations in Nigeria between 1985 and 1991 and stored at the University College Hospital in Ibadan. A total of 4,153 sera were collected from participants in the National Immunity Survey of Viral Infections (n = 1,640), patients with tuberculosis (TB) (n = 140), patients with sexually transmitted diseases (STDs) (n = 876), patients with other medical conditions (n = 1,285), female prostitutes (n = 60), and health care workers (n = 152). The overall seroprevalence of HTLV was 5.6%, with similar rates among males and females. Using enzyme immunoassays that differentiated between antibodies to the two viruses, the seroprevalence rates were 2.5% for HTLV-I and 1.9% for HTLV-II, with an additional 1.2% of the samples dually reactive for both HTLV-I and HTLV-II. The seroprevalence rates for HTLV were low among children (0.8%) and adolescents (1.7%), with substantially higher rates among adults (range 5.0-7.4%). Age-specific patterns among adults appears to differ for HTLV-I and HTLV-II, with HTLV-I rates peaking above age 50 and HTLV-II rates peaking below age 50. The highest overall HTLV prevalence rates were observed for STD patients (16.3%), followed by female prostitutes (8.3%), TB patients (6.4%), health care workers (3.3%), patients with other medical conditions (3.2%), and immunity survey participants (1.8%).(ABSTRACT TRUNCATED AT 250 WORDS)

Viral agents associated with infantile gastroenteritis in Nigeria: relative prevalence of adenovirus serotypes 40 and 41, astrovirus, and rotavirus serotypes 1 to 4

Sixty-six stool specimens from infants with diarrhoea in Nigeria were examined for the presence of viral pathogens. Rotaviruses were found in 25.8% of specimens and astroviruses in 1.5%. Serotypes were determined for 47.1% of the rotavirus positive specimens, all of which were serotype 1. RNA analysis revealed no unusual electrophoretic profiles. No enteric adenoviruses were detected. In contrast, in a parallel study conducted in the UK, rotaviruses (including serotypes 1, 2 and 4) accounted for 21.9% of infections, adenovirus serotypes 40 and 41 13.6%, and astroviruses 4.5%.