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.

Neuroprotective potential of plant derived parenchymal stem cells extract on environmental and genetic models of Parkinson disease through attenuation of oxidative stress and neuroinflammation

Parkinson's disease (PD) is a neurodegenerative disorder characterized by both motor and non-motor features. The current treatment regimen for PD are dopamine enhancers which have been reported to worsen the disease prognosis after long term treatment, thus, the need for better treatment options. This study sought to investigate the protective action of Double Stem Cell® (DSC), a blend of stem cells extracts from Swiss apples (Malus Domestica) and Burgundy grapes (Vitis vinifera) on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinsonism in mice and genetic model of PD in Drosophila melanogaster. Male albino mice were pretreated with MPTP (4 × 20 mg/kg, i.p., two hourly in 8 h), twelve hours before administration of DSC (8, 40, or 200 mg/kg, p.o.). Thereafter, behavioural, biochemical and immunohistochemical assays were carried out. The impact of vehicle or DSC supplementation on α-synuclein aggregation was evaluated in Drosophila melanogaster using the UAS-Gal4 system, female DDC-Gal4 flies were crossed with male UAS-α-synuclein, the progenies were examined for fecundity, locomotion, memory, and lifespan. MPTP-induced motor deficits in open field test (OFT), working memory impairment (Y-maze test (YMT)) and muscle incoordination (rotarod test) were ameliorated by DSC (8, 40 or 200 mg/kg) through dose-dependent and significant improvements in motor, cognitive and motor coordination. Moreso, MPTP exposure caused significant increase in lipid peroxidation and decrease in antioxidant enzymes activities (glutathione, catalase and superoxide dismutase) in the midbrain which were attenuated by DSC. MPTP-induced expression of microglia (iba-1), astrocytes (glia fibrillary acidic protein; GFAP) as well as degeneration of dopamine neurons (tyrosine hydroxylase positive neurons) in the substantia nigra (SN) were reversed by DSC. Supplementation of flies feed with graded concentration of DSC (0.8, 4 or 20 mg/ml) did not affect fecundity but improved climbing activity and lifespan. Findings from this study showed that Double Stem Cell improved motor and cognitive functions in both mice and Drosophila through attenuation of neurotoxin-induced oxidative stress and neuroinflammation.

Saliva sample for detection of SARS-CoV-2: A possible alternative for mass testing

Molecular diagnostic testing has played a critical role in the global response to the novel Coronavirus disease (COVID-19) pandemic, since its first outbreak in late 2019. At the inception of the COVID-19 pandemic, nasopharyngeal swab sample analysis for COVID-19 diagnosis using the real-time polymerase chain reaction (RT-PCR) technique was the most widely used. However, due to the high cost and difficulty of sample collection, the number of available sample types for COVID-19 diagnosis is rapidly increasing, as is the COVID-19 diagnostic literature. The use of nasal swabs, saliva, and oral fluids as viable sample options for the effective detection of SARS-CoV-2 has been implemented successfully in different settings since 2020. These alternative sample type provides a plethora of advantages including decreasing the high exposure risk to frontline workers, enhancing the chances of home self-sampling, reducing the cost, and significantly increasing testing capacity. This study sought to ascertain the effectiveness of Saliva samples as an alternative for COVID-19 diagnosis in Nigeria. Demographic data, paired samples of Nasopharyngeal Swab and Drooling Saliva were obtained from 309 consenting individuals aged 8–83 years presenting for COVID-19 testing. All samples were simultaneously assayed for the detection of SARS-CoV-2 RdRp, N, and E genes using the GeneFinder^™ COVID-19 Plus RT-PCR test kit. Out of 309 participants, only 299 with valid RT-PCR results comprising 159 (53.2%) males and 140 (46.8%) females were analyzed in this study using the R Statistical package. Among the 299 samples analyzed, 39 (13.0%) had SARS-CoV-2 detected in at least one specimen type. Both swabs and saliva were positive in 20 (51.3%) participants. Ten participants (25.6%) had swab positive/saliva-negative results and 9 participants (23.1%) had saliva positive/swab-negative results. The percentage of positive and negative agreement of the saliva samples with the nasopharyngeal swab were 67% and 97% respectively with positive and negative predictive values as 69% and 96% respectively. The findings indicate that drooling saliva samples have good and comparable diagnostic accuracy to the nasopharyngeal swabs with moderate sensitivities and high specificities.

Full length genomic sanger sequencing and phylogenetic analysis of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Nigeria

In an outbreak, effective detection of the aetiological agent(s) involved using molecular techniques is key to efficient diagnosis, early prevention and management of the spread. However, sequencing is necessary for mutation monitoring and tracking of clusters of transmission, development of diagnostics and for vaccines and drug development. Many sequencing methods are fast evolving to reduce test turn-around-time and to increase through-put compared to Sanger sequencing method; however, Sanger sequencing remains the gold standard for clinical research sequencing with its 99.99% accuracy This study sought to generate sequence data of SARS-CoV-2 using Sanger sequencing method and to characterize them for possible site(s) of mutations. About 30 pairs of primers were designed, synthesized, and optimized using endpoint PCR to generate amplicons for the full length of the virus. Cycle sequencing using BigDye Terminator v.3.1 and capillary gel electrophoresis on ABI 3130xl genetic analyser were performed according to the manufacturers’ instructions. The sequence data generated were assembled and analysed for variations using DNASTAR Lasergene 17 SeqMan Ultra. Total length of 29,760bp of SARS-CoV-2 was assembled from the sample analysed and deposited in GenBank with accession number: MT576584. Blast result of the sequence assembly shows a 99.97% identity with the reference sequence. Variations were noticed at positions: nt201, nt2997, nt14368, nt16535, nt20334, and nt28841-28843, which caused amino acid alterations at the S (aa614) and N (aa203-204) regions. The mutations observed at S and N-gene in this study may be indicative of a gradual changes in the genetic coding of the virus hence, the need for active surveillance of the viral genome.

Monitoring of Lassa virus infection in suspected and confirmed cases in Ondo State, Nigeria

Introduction

Lassa virus (LASV), the causative agent of Lassa fever (LF), an endemic acute viral haemorrhagic illness in Nigeria, is transmitted by direct contact with the rodent, contaminated food or household items. Person-to-person transmission also occurs and sexual transmission has been reported. Thus, this study investigated the presence of LASV in body fluids of suspected and confirmed cases.

Methods

this was a cross-sectional study between March 2018 and April 2019 involving 112 consenting suspected and post ribavirin confirmed cases attending the Lassa fever treatment center in Ondo State. Whole blood was collected from 57 suspected and 29 confirmed cases. Other samples from confirmed cases were 5 each of High Vaginal Swab (HVS) and seminal fluid; 12 breast milk and 4 urine. All samples were analyzed using reverse transcription-PCR (RT-PCR) targeting the S-gene of LASV.

Results

analysis of whole blood by RT-PCR showed that 1/57 (1.8%) suspected and 1/29 (3.4%) confirmed post ribavirin treated cases were positive. While LASV was detected in 2/5 (40%) post ribavirin treated seminal fluids and 1/11 (8.3%) breast milk. However, LASV was not detected in any of the HVS and urine samples.

Conclusion

the detection of LASV in seminal fluid and breast milk of discharged post ribavirin treated cases suggests its persistence in these fluids of recovering Nigerians. The role of postnatal and sexual transmissions in the perennial outbreak of LF needs to be further evaluated.

Parvovirus B19 DNA detection in treatment-naïve HIV anemic patients in Lagos, Nigeria: a case control study

BACKGROUND

Parvovirus B19 (B19) has tropism for cells of the erythroid lineage, which may lead to transient inhibition of erythropoiesis. Several studies and case reports suggested that B19 infection may contribute significantly to severe chronic anemia in HIV infected persons.

OBJECTIVE

To detect parvovirus B19 DNA in treatment-naïve HIV patients.

METHODS

This was a case control retrospective study. One hundred nineteen anemic and 81 non-anemic treatment-naïve HIV infected patients participated in the study at the Lagos University Teaching Hospital, Lagos, Nigeria. Polymerase chain reaction was used to detect B19 DNA.

RESULTS

Out of 200 patients analysed, 13(6.5%) had parvovirus B19 DNA. Eight HIV patients with anemia had B19 DNA while five non-anemic HIV patients had B19 DNA. This suggests that the presence of B19 DNA in the blood of HIV positive individuals may contribute to anemia because the majority (61.5%) who were positive for B19 DNA had anemia as compared to the non-anemic control group (38.5%).

CONCLUSION

This study shows that the presence of B19 DNA in anemic HIV infected patients is not associated with chronic anaemia in HIV infection because no significant association exist.

The West African ebola virus disease epidemic 2014-2015: A commissioned review

The first epidemic of Ebola haemorrhagic disease in West Africa is the largest and longest Ebola epidemic till date, where the outbreak notably involved three countries with distant spread to other countries. It has caused significant mortality, with reported case fatality rates of up to 70%. Data and relevant information were extracted from the review of majorly relevant publications/papers about the Ebola epidemic in West Africa and other previous outbreaks of Ebola virus (EBOV). As of 2016, with the epidemic under control, the World Health Organization has warned that flare-ups of the disease are likely to continue for some time as recently occurred in Sierra Leone and the on-going in Guinea. As this may not be the last outbreak of Ebola virus disease (EVD) in West Africa, there is a need to focus on diagnostic and research capacity required to curtail EVD with adequate measures for emergency preparedness and policies for innovative treatment strategies.

Seroprevalence of hepatitis B virus infection among pregnant women at the antenatal booking clinic of a Tertiary Hospital in Lagos Nigeria

OBJECTIVES

The objectives were to determine the seroprevalence of hepatitis B virus (HBV) infection and assess the major risk factors among Nigerian pregnant women.

SUBJECTS AND METHODS

This was a cross-sectional descriptive study carried out among pregnant women at the antenatal clinic of a Tertiary Hospital in Lagos, Nigeria. A total number of 150 consenting pregnant women were selected for the study. A structured pretested interviewer-administered questionnaire was used for the data collection. Sera were collected and tested for hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg).

RESULTS

Of the 150 women screened during the study, 11 (7.3%) were seropositive for HBsAg. Of these 11 women, 4 (36.4%) were also positive for HBeAg. There was no statistically significant difference in the mean ages of participants who were seropositive for HBsAg and those who were negative for the virus (P=0.888). There were statistically significant differences in the seroprevalence of HBsAg recorded among respondents with previous surgery (odd ratio [OR]-2.97; 95% confidence interval [CI]-1.08-16.67; P=0.046), previously affected sibling or spouse (OR-5.03; 95% CI-1.11-25.27; P=0.001) and those with two or more lifetime sexual partners (OR-4.11; 95% CI-2.85-9.22; P=0.024).

CONCLUSION

The sero-prevalence rate of HBV infection and also its infectivity is high in Lagos, Nigeria. These findings thus support the need for a nationwide policy of routine and widespread HBV screening among pregnant women.

Detection of avian influenza virus from fecal samples of poultry birds in Lagos State

BACKGROUND

Although there have been a lot of research done on Avian Influenza in the world, there are still visible indications in the Nigerian poultry farming system that the bio-security measures are not adhered to strictly. Hence, it is of great importance to identify the circulating strains of Avian Influenza virus in Nigeria, so as to prevent and control another outbreak of the disease.

METHODS

Between May and June 2011, 184 stool samples were collected from seemingly healthy poultry birds in Ikorodu and Ejigbo, within Lagos state. RNA extraction using diatomaceous sand method and Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) was carried out on all samples.

FINDINGS

Influenza virus type A 25(13.6%) was detected from poultry B (Ejigbo poultry), while there was no positive sample from poultry A (Ikorodu Poultry), the positive samples were further sub-typed, and H1 [1(4%)] was detected. Altogether, 159 (86%) of the fecal samples collected gave a. negative result for Influenza A, and also, 24(96%) out the 25 samples positive for Influenza A gave tested negative when subtyped with H1 and H3.

INTERPRETATION

Results of the samples gotten from both poultries corroboratethe effect of poor bio-security practicesin the spread of Influenza A viruses and that some poultries in Nigeria are not adhering to proper farm bio-security practices. Also the identification of H1 subtype which is human adapted is indicative of a re- emerging potential threat to public health.

Hepatoprotective and antioxidant activities of Hepacare®, a herbal formulation against carbon tetrachloride-induced liver injury

BACKGROUND

Hepacare(®) is a herbal formulation used to treat patients with sickle-cell anaemia complicated with jaundice, also recommended as a protective agent against liver damage due to chronic ingestion of alcohol.

METHODS

In vitro antioxidant properties of Hepacare(®) was determined using 1, 1- diphenyl-2-picryl-hydrazyl (DPPH), total antioxidant capacity, reducing power ability, and nitric oxide assays. Hepatoprotective effect of Hepacare(®) (50-400 mg/kg/day for 7 days, p.o.) was investigated in male Sprague Dawley rats against carbon tetrachloride (CCl(4) /olive oil, 1:1, 0.7 ml/kg, i.p.)-induced liver damage. At the end of the study, blood samples and liver tissue were assayed for biochemical and antioxidants parameters.

RESULTS

Hepacare produced concentration dependent inhibition of DPPH and nitric oxide activity with IC(50) of 48.50 and 55.00 µg/ml, respectively, it suppressed the absorbance of ABTS(.+) with total antioxidant capacity of 423.47±8.37 mg QUE/g. CCl(4) administration induced significant (P<0.001) elevation of serum aspartate transaminase (1.70 fold), alanine transaminase (1.60 fold), alkaline phosphatase (2.90 fold) and bilirubin (2.00 fold) in comparison to control. The increase in serum biomarker were dose-depen-dently reversed by Hepacare(®) pretreatment. More-over, CCl(4) pretreatment increased (P<0.001) malondialdehyde (MDA) (73.98%) and decreased (P<0.001) antioxidant enzymes level but Hepacare pretreatment produced dose-dependent attenuation of the increased MDA (3.84 fold) with enhancement of glutathione (3.08 fold), superoxide dismutase (2.08 fold), and catalase (3.14 folds) levels in comparison to CCl(4) treated group, similar to those of silymarin reference standard.

CONCLUSION

Hepacare was beneficial in the prevention of CCl(4)-induced hepatocellular injury, possibly by scavenging reactive free radicals, and boosting endogenous antioxidant systems.

Seroprevalence of other antibodies (herpes, CMV, rubella, varicella, hepatitis B and C, syphilis, chlamydia, mumps, toxoplasmosis) in HIV-positive patients

We attempted to determine the seropositivity of HIV-positive patients to other antibodies (herpes, CMV, rubella, varicella, hepatitis B, hepatitis C, syphilis, chlamydia, mumps, toxoplasmosis). The study was carried out at the Prenatal Diagnosis and Therapy Centre of a Tertiary Hospital in Lagos, Nigeria. A total of 70 patients (50 females and 20 males) attending the centre between June 1997 and December 2005 who were screened and found to be HIV-seropositive were further screened for herpes simplex IgG/IgM, CMV IgG/IgM, rubella IgG/IgM, varicella IgG/IgM, mumps IgG/IgM, toxoplasmosis IgG/IgM, chlamydia IgG/IgM, hepatitis B and hepatitis C IgG/IgM using ELISA kits and syphilis (THPA) using the HAE method. Our study showed that a large number of HIV-positive patients are carriers of other antibodies and should be screened for them before therapy.

Early-onset sensorineural hearing loss in Lassa fever

Lassa fever (LF) is a viral hemorrhagic disease which affects one-fourth to two million people annually with the fatality rate of about 10,000. It is associated with sensorineural hearing loss (SNHL) usually at the convalescent stage. Recently, cases of SNHL at the acute phase have been reported. This study was done to further investigate the incidence and features of SNHL in acute phase of LF. It is a prospective case-control study of LF patients seen with acute SNHL conducted between July 2007 and April 2009 at Irrua Specialist Teaching Hospital Nigeria. The diagnosis of acute LF was based on the clinical features and detection of IgM antibodies and/or positive Lassa virus-specific reverse transcriptase-polymerase chain reaction using primers S36+ and LVS 339 while SNHL was diagnosed clinically and confirmed with PTA and speech discrimination tests. Patients with other acute febrile illnesses were used as control. Statistical analysis was done using SPSS version 11 and Fisher's exact test while level of significance was set at p < 0.05. Out of the 37 confirmed cases of LF, 5 (13.5%) and none (0%) of the control developed early-onset SNHL (p = 0.03). Forty percent of the cases studied had negative IgM. The audiograms showed involvement at all frequency groups with pure tone average 65-85 dB and the speech discrimination 20-40%. The overall case fatality rate was 27.0%, and for early SNHL cases 60.0% (p > 0.05). The incidence of SNHL in LF infection is about 13.5% and could be a reflection of a worse disease process. There is possibility of direct viral invasion aside immunological reaction as a causative mechanism.

Efficacy of HIV PCR techniques to diagnose HIV in infants born to HIV infected mothers at LASUTH

BACKGROUND

There has been so many difficulties encountered in the diagnosis of HIV infection in infants < 18 months of age born to HIV-infected mother. In these infants, definitive diagnosis can only be carried out by antigen based techniques which are expensive and not widely available in developing countries.

OBJECTIVE

To generate information on the rate of mother to child transmission in Nigeria and to compare the efficacies of both the HIV-1 RNA and HIV-1 DNA PCR techniques in the diagnosis of this infections in infants.

METHOD

Ninety (90) whole blood samples were obtained from 45 HIV positive mothers and 45 infants born to these mothers from the Department of Obstetrics and Gynaecology, Lagos State University Teaching Hospital (LASUTH), Ikeja, Lagos. The presence of HIV was determined using the Amplicor HIV-1 DNA test and an in-house RNA PCR method.

RESULTS

All the infants were HIV antibody positive, however, only 5 infants were positive by HIV-1 DNA PCR, indicating an 11% rate of transmission from HIV positive mothers. Among the 5 infants positive by the DNA PCR, only 4 were positive for the in-house RNA PCR.

CONCLUSION

The 11% transmission rate recorded in this study was similar to that from mothers' who had Nevirapine ART interventions and both the HIV-1 DNA test and the in-house RNA PCR tests were sensitive and specific in the diagnosis of infection in infants, depending on the level/ state of HIV infection in infants.

Prenatal diagnoses of cytomegalovirus (CMV), rubella, toxoplasmosis, varicella, parvovirus, herpes simplex and syphilis. the Lagos programme experience

Prenatal diagnosis of infectious diseases has been shown to be indispensable to confirm or exclude in utero infections due to cytomegalovirus, rubella, toxoplasmosis, varicella, parvovirus and herpes simplex, and a multidisciplinary approach is needed. Our report is on data obtained from 236 pregnant women at risk for the above-mentioned conditions. The specific IgM test suggested seroconversion in only 198 of these patients and 162 of them requested prenatal diagnoses by means of fetal blood sampling or amniocentesis, or both. The results are encouraging but more work is required to optimize our diagnostic approach, i.e., monoclonal antibodies and DNA probes with direct identification by means of choronic villi sampling, which we use for prenatal diagnoses of hemoglobinopathy (DNA-genetic).

Prevalence of rotavirus-induced diarrhea among children under 5 years in Ilorin, Nigeria

Diarrhoea disease is an important cause of morbidity and mortality in Nigerian children and rotavirus has been identified as an important causative agent among children below 5 years. We determined the prevalence of rotavirus-induced diarrhoea among under-5 s by electrophenotyping. Stool samples were collected from eligible subjects who presented with acute diarrhoea. The samples were processed for viral studies by electrophenotyping. Among the 299 subjects recruited, 55.9% were positive for rotavirus. Eighty percent of the recruited patients were below 24 months. There was a significant decrease (p-value = 0.00001) in the prevalence of rotavirus among diarrhoea patients above the age of 24 months when compared with those below this age group. Rotavirus was associated with higher morbidity and mortality. We conclude that rotavirus is the most important cause of diarrhoea among children <5 years in Ilorin, Nigeria and its prevalence is highest in the first 2 years of life. Adequate rehydration should be regarded as the mainstay of management.

Viral diarrhoea in young children in two districts in Nigeria

OBJECTIVES

To determine the prevalence of viral agents of diarrhoea in Ilorin and Lagos, two zones in Nigeria.

DESIGN

A survey of young children who had clinically confirmed diarrhoea.

SETTING

University of Ilorin Teaching Hospital in Ilorin, Kware State and the Massey Street Children's Hospital in Lagos State, Nigeria.

SUBJECTS

108 children under the age of five.

RESULTS

The prevalence rates observed were 33.3% for rotavirus, 6.7% for adenovirus and 1.2% for astrovirus. The rotavirus strains were characterized further. PAGE determined the presence of seven patterns of RNA electropherotypes, with one short RN patterns and six long patterns. The G and P types of selected rotavirus positive samples were characterized by RT-PCR techniques. The VP7 G typing showed that GI was the most prevalent single strain found (8.3%), while G3 and G4 accounted for 6.7% and 1.7%. The rate of mixed G serotypes was 26.7%. The P[6] genotype was the most prevalent (52%) and the P[4] had a prevalence of 8%. The mixed P genotype accounted for 28% of the rotavirus strains. The high rate of mixed infection may have an implication on vaccine development.

CONCLUSION

Rotavirus was the most prevalent virus in the study with astrovirus being the second most prevalent. There was only a single incidence of astrovirus.

Viral isolates of intussusception in Nigerian infants

Idiopathic intussusception is associated with viral pathogens of gastrointestinal respiratory and febrile diseases of infancy and early childhood. These agents are known to vary from one region to another. No such specific viruses have, however, been reported from Nigeria. We therefore collected stools from 28 infants with intussusception as well as 20 age- and sex-matched healthy controls and subjected these specimens to viral isolation techniques. Of the 21 viral isolates obtained from the two groups, 17 (81%) were from the intussusception group while 4 (19%) were from the controls. Ten (58.8%) of the 17 isolates from these subjects were identified as adenoviruses using monoclonal antibody. All of them were from the intussusception group. None of the four isolates from the controls significantly reacted with this antibody. We concluded that adenoviruses are strongly associated with primary intussusception in Nigerian infants.

Measles HI-antibody levels in Lagos children, Nigeria: a follow-up study to resurgence of measles in Lagos metropolis

A total of 138 children aged between 0-36 months were bled and screened for measles haemagglutination inhibiting (HI)-antibody. Twenty seven children were from age group (0-4) months with 16 (59.3%) seropositive while, 67 and 44 were bled in the group (5-9) and > or = 12 months with 29 (43.3%) and 31 (70.5%) sero positive sera respectively. The distribution of the antibody titre pattern among various age groups suggest vaccination against measles should be at age 9 month. The antibody titres pattern of seroconverted vaccinees also showed that the vaccine administered at our study centre were potent enough to elicit good and protective immune response in vaccinees when given at age 9 month. Our study agrees with the current policy of vaccinating children against measles at age 9 months in Nigeria and should therefore be continued. Based on observations in this study, we suggest; continued administration of the Edmonston-Zagreb strain of measle vaccine currently-in-use in Nigeria, mother's breast-feeding of children for a longer period before the apporpriate age for vaccination, and the possible administration of Vitamin A-a potent immune enhancer, as a supplement during immunization programmes in Nigeria. The introduction of a booster dose of measles vaccine at elementary school age in order to care for the residual unvaccinated children may be a good strategy for measles eradication necessary to be considered in Nigeria and might probably forestall instances of measles outbreaks in children during their second year in school.

Zoonotic infections in Nigeria: overview from a medical perspective

Infections of domestic and wild animals that are transmitted directly or by an arthropod vector to humans are a major cause of morbidity and mortality worldwide and particularly in Nigeria. With a population of over 100 million and the need for improved health care delivery, Nigerians are at considerable risk considering the seriousness of these infections. Zoonotic infections that are endemic in Nigeria include tuberculosis, trypanosomiasis, toxoplasmosis, taeniasis, rabies, lassa fever and yellow fever. Zoonotic food-borne infections (caused by Campylobacter, Salmonella and Escherichia coli O157:H7) and cryptosporidiosis are emerging. Sporadic cases such as strongyloidiasis, ascariasis, leptospirosis, scabies, pentastomiasis and African histoplasmosis have been reported. There is a need to determine the prevalence of tick-borne zoonoses. Prevention and control of zoonoses in humans is by vaccination, treatment and health education. As a first measure to improve control, the link between veterinary and medical officers, which is presently very weak, needs to be strengthened. Furthermore, regional multidisciplinary approaches to the control of zoonotic infections should be adopted in West Africa, which take into consideration the huge inter-border traffic.

Potency status and efficacy of measles vaccine administered in Nigeria: a case study of three EPI centres in Lagos, Nigeria

The potency status and efficacy of measles vaccines were studied in three immunization (EPI) centres in the suburban area of Lagos, Nigeria. A total of 14 vials of measles vaccine were collected and subjected to potency testing while, 203 measles-vaccinated children were recruited for this study. Only 85 (41.87%) of the vaccinees reported back for the post-vaccination follow-up screening. The seroconversion pattern showed that 51(60%) had potent antibody titres ranging from 1:40 to 1:1280, while the remaining 34 (40%) had a low antibody titres between < 1:20 and 1:20. The vaccine potency test showed that only 1 (7.14%) of the 14 vaccine vials collected at these centres had virus titre of 3.5 Log while the remaining 13 (92.86%) had virus titres lower than 3.0 Log: the recommended human dose by the World Health Organisation (WHO) for measles vaccine. The administration of these subpotent and/or impotent vaccines vis-à-vis the status of immune response elicited in the vaccinees may be one of the reasons for the occurrence of measles infection in vaccinated children in the recent time in Nigeria. We herein suggested the subjection of all vaccines to a thorough standard laboratory screening before use in Nigeria.

Genotypic and antigenic characterization of hemagglutinin proteins of African measles virus isolates

A comprehensive phylogenetic study based on the hemagglutinin (H) protein of all known African measles virus (MV) isolates is presented. The study includes 64 new H gene sequences from Ghana. Nigeria and South Africa as well as viruses from Zambia and The Gambia for which only incomplete sequencing data were available and that have previously not been genotyped. The results provide further support to the tentative assignment of the Nigerian and Ghanaian viruses to a new genotype B3 within clade B. A distinct geographic distribution pattern emerged with clade B viruses circulating exclusively in African countries north of the equator. All MV strains from southern Africa grouped in clades A and D with the majority of viruses belonging to genotype D4. The viruses considerably differed by their sensitivity to neutralization by monoclonal antibodies (mAb), but three selected antibodies were sufficient to distinguish between African MVs representing four different genotypes.

Molecular epidemiology of Nigerian and Ghanaian measles virus isolates reveals a genotype circulating widely in western and central Africa

Sub-Saharan Africa is one of the regions of the globe with the highest measles-related morbidity and mortality. Yet only seven virus isolates from this vast region have been phylogenetically characterized on the basis of their nucleoprotein, the last one in 1991. To characterize the prevalent wild-type viruses and to understand their circulation pattern, a large panel (n = 45) of isolates was collected in Ghana and Nigeria in 1997 and 1998. On the basis of their nucleoprotein sequence, the viruses clearly belong to clade B but a reshuffling of the structure of this clade was proposed, tentatively extending the number of genotypes from two to three on the basis of quantitative criteria. The sequences revealed the co-circulation of at least two distinct viruses in the cities of Lagos and Ibadan, suggesting that the number of susceptible individuals seems to be high enough to support endemic circulation of at least two distinct viruses. The endemic co-circulation of several viruses may well be a characteristic of communities with low vaccination rates. One of these viruses was also found in Accra in 1998 as well as in a 1994 case linked to distant Kenya, suggesting that clade B viruses are prevalent in sub-Saharan Africa while non-B viruses seem to dominate the south of Africa.

Wesselsbron virus antibody in domestic animals in Nigeria: retrospective and prospective studies

Retrospective and prospective serological surveys to determine the prevalence of Wesslsbron (WSL) virus infections in animal populations were carried out in different vegetational zones in Nigeria. Sera from 1,492 animals comprising 292 camels, 81 horses, 4 donkeys, 320 cattle, 235 sheep, 260 goats, 114 pigs, 101 dogs and 85 domestic fowls were assayed by haemagglutination-inhibition (HI) test for presence of antibodies to WSL virus and other flavivirus antigens: Yellow Fever (YF), Potiskum (POT), Banzi (BAN), Uganda S (UGS) and West Nile (WN) viruses. Four hundred and eighty one (32%) of the total sera tested were positive for the presence of flavivirus antibodies. The prevalence rates among animals varied with species and vegetational zones of the country. The highest prevalence was noted in animals from a swamp forest zone and was higher among camels, horses, donkeys and sheep when compared with goats, pigs and fowls in different zones. Although monotypic reactions with WSL virus antigen were observed in positive sera, the majority of the WSL virus positive sera cross-reacted with more than two other flavivirus antigens. Serological cross-reactions were most extensive in WSL virus positive horse sera. A ten month sentinel survey among 28 cattle, 68 sheep and 30 goats revealed considerable activity of WSL virus in Nigeria. Of these, 11 cattle and 12 sheep showed antibody conversion to WSL virus antigen. None of the goats seroconverted. Although, there are no records of outbreak of WSL disease in Nigeria, this study revealed that WSL virus is actively circulating among livestock populations in this environment. Flavivirus nucleotide data are needed for final determination of genetic relatedness in this group of viruses.

Severe post-vaccination reaction to 17D yellow fever vaccine in Nigeria

An unusual outbreak of post-vaccination reactions to 17D yellow fever vaccine occurred at Shaki, Nigeria, in May 1987. Twenty-five of the affected people were treated at the Baptist Hospital Shaki. The patients presented with rapidly progressing swelling of the left arm with associated fever and other constitutional symptoms few hours after inoculation with the vaccine. Some of the patients developed gangrene of the affected limb, five of them went into coma and died. Poor hygiene and improper handling of vaccine as well as contamination of vaccine from the source are possible causes. A review of vaccine delivery strategies especially at local community levels; sound training, supervision of vaccinators and health education are strongly recommended to prevent reoccurrence of similar reactions.

Isolation and identification of African horse sickness virus during an outbreak in Lagos, Nigeria

An outbreak of African horse sickness involving two horse stables in Lagos, Nigeria, was investigated. Inoculation of blood from infected horses into suckling albino mice resulted in isolation of a virus which was identified as African horse sickness virus by the complement fixation test. The clinical, pathological and epizootiological findings (reported elsewhere) were consistent with African horse sickness. Potential threats of the epidemic to international horse trade are briefly highlighted.

Prevalence of human immunodeficiency virus types 1 and 2 infections in Nigeria

The prevalence of human immunodeficiency virus (HIV) types 1 and 2 infections in Nigeria was estimated from 3854 serum samples collected at 21 locations from 1985 to 1990. Seventy-eight samples (2.0%) were reactive for HIV-1 and 49 (1.3%) for HIV-2 antibodies; 5 samples were reactive for both viruses. The prevalence of HIV-1 and -2 infections, respectively, was highest among 60 female prostitutes, with 10% and 6.7% positive. For other groups the respective rates of positivity were 4.1% and 3.4% in 610 patients with sexually transmitted diseases, 3.6% and 1.4% in 140 tuberculosis patients, 1.6% and 0.6% of 1253 other medical patients, and 1.2% and 0.9% of 1640 volunteer blood donors. Of 153 health care workers, 1.3% were positive for HIV-1 only. The age group from 20 to 29 years had the highest prevalences of HIV-1 (3.3%) and -2 (2.2%). In Nigeria, antibody prevalence for both viruses appears to have increased > 10-fold between 1986 and 1990.

Complement fixing antibodies against selected viruses in diabetic patients and non-diabetic control subjects in Ibadan, Nigeria

Sera of forty insulin-treated Nigerian diabetics attending the outpatients clinic of the University College Hospital (U.C.H.), Ibadan, and an equal number of non-diabetic control subjects matched for age, sex and social status were tested for presence of complement fixing (CF) antibodies against five viruses: Coxsackie A and B1, mumps rubella and enterovirus group antigen. Antibody levels to Coxsackie B1, mumps, rubella and enterovirus did not show any significant difference between the two groups (P > 0.05). The serum levels of antibody to Coxsackie A virus were significantly higher in non-diabetic controls than in the diabetics (P < 0.05). Previous exposure to these viruses may not be a significant factor in the aetiology of insulin dependent diabetes mellitus in this environment.

A survey for haemagglutination-inhibiting antibody to West Nile virus in human and animal sera in Nigeria

A survey for West Nile Virus (WNV) haemagglutination-inhibition (HI) antibody was carried out in humans and domestic animals. Human sera were collected from Ibadan, while the animal sera were collected from both Ibadan and Maiduguri. Out of 304 human sera tested, 123 were positive (40%). There was a higher prevalence of HI antibody in adults than children. Sex distribution of positive sera showed that 37% of males and 43% of females had WNV HI antibody. There was no significant difference in the prevalence of HI antibody in both sexes. On the 123 WNV HI positive sera tested, 104 (85%) and 78 (75%) had yellow fever and Potiskum HI antibody respectively. Monotypic WNV virus reactions were frequently found in children while polytypic reactions were frequently found in adults. A total of 200 animal sera were examined, 50 camels, 50 goats, 49 cattle and 51 sheep. The highest prevalence of HI antibody was found in camels (26%), followed by sheep (20%). Percentage of positive sera in other species were: goat (18%) and cattle (6%). Of the 35 WNV HI positive animal sera, 26 and 20% reacted with Yellow fever and Potiskum virus antigens respectively.

Cytomegalovirus infection among tuberculosis patients in a chest hospital in Nigeria

A serological study was carried out in Ibadan, Nigeria to determine the prevalence of inapparent infection with cytomegalovirus among tuberculosis patients and its relation to the epidemiology of the virus in this environment. A total of 360 sera from 161 tuberculosis patients, 89 patients other than tuberculosis and 110 healthy voluntary blood donors were examined for antibody to cytomegalovirus by the complement fixation test. One hundred and forty-one (87.6%) of the tuberculosis patients, 45 (50.6%) patients other than tuberculosis and 60 (54.6%) healthy blood donors had a complement fixing antibody to cytomegalovirus. Although the total prevalence (68.3%) of complement fixing antibody against cytomegalovirus in all the groups is high, it is higher among the tuberculosis patients than the other groups in the same environment. This shows that tuberculosis which is still a major health problem in Nigeria may be playing a significant role in the spread of cytomegalovirus in the country.

Yellow fever haemagglutination-inhibiting, neutralising and IgM antibodies in vaccinated and unvaccinated residents of Ibadan, Nigeria

A survey for yellow fever virus haemagglutination inhibiting (HI) and neutralising (N) and IgM antibodies was carried out in unvaccinated people in Ibadan and in those immunised with the yellow fever 17-D vaccine. A total of 207 people were tested for HI antibody to yellow fever and two other flaviviruses namely: Wesselsbron and Uganda S. viruses. Prevalence of HI antibody to each flavivirus antigen was as follows: Yellow fever 26%, Wesselsbron 18% and Uganda S 33%. Of the 207 people, 37 (18%) had yellow fever N antibody. There was a higher prevalence of N antibody to yellow fever virus in adults than children. Twenty-one people vaccinated with 17-D yellow fever vaccine donated post-vaccination sera; 10 (48%) had no prevaccination HI antibody, 7 (33%) had HI antibody to one flavivirus and 4 (19%) to two or more flaviviruses. Ninety percent of seronegative people and all those with prevaccination flavivirus antibodies developed HI or N antibody, following vaccination. A total of 58 unvaccinated people were tested for yellow fever IgM antibody by an enzyme linked immunosorbent assay, 2 (3%) were positive; suggesting that active yellow fever transmission was in progress at the time of survey.

Serological evidence for influenza virus activity in Nigeria (1985-1987)

A study to determine the activity of influenza virus among the children population was undertaken between 1985 and 1987 in Nigeria. Paired sera were obtained from children presenting with respiratory diseases at the children emergency and outpatient clinics of the University College Hospital, Ibadan. Forty-two paired sera were examined by haemagglutination-inhibition test to determine HI antibody level of the patients to different serotypes of influenza virus. Ninety percent of the children showed serological evidence of previous contact with influenza A virus subtypes while only 24% were positive when tested against influenza B virus. Twenty-two of the 42 children tested seroconverted to influenza A virus strains while only 2 seroconverted to influenza B virus strain used. Out of the 22 children that seroconverted to influenza A virus, 14 were due to H3N2 A/Mississippi 1/85, 4 to H3N2 A/Leningrad 360/86 and 2 each seroconverted to H1N1 A/Chile 1/83 and H1N1 A/Taiwan 1/180. Two other individuals showed serological conversion to either H3N2 A/Mississippi 1/85 and H1N1 A/Chile 1/83 or H3N2 A/Mississippi 1/85 and H1N1 A/Taiwan 1/86. While cases were seen throughout the year during the period under review, more cases occurred during early (April-May) to peak raining season (September) and during harmattan period (November) in Ibadan area where the study was conducted. It is evident from this study that continuous and synchronous circulation of influenza viruses occur in this environment. There is therefore danger of influenza epidemic under depressed immunity and if the virus is introduced into population with low level of immunity in other parts of the country.

Wesselsbron virus infection in West African dwarf goats (Fouta djallon): virological and immunological studies

West African dwarf goats were experimentally infected with Nigerian strain of Wesselsbron virus. Viraemia was detected in infected goats 2 days after infection and lasted for one day. A 100% mortality was observed among the infected animals; the virus was reisolated in mice from almost every tissue obtained from the bodies of infected goats. In addition, the infected goats developed complement-fixing and haemagglutination inhibiting antibodies to Wesselsbron virus.

Igbo-Ora virus (an alphavirus isolated in Nigeria): a serological survey for haemagglutination inhibiting antibody in humans and domestic animals

Sera from humans and animals were tested for antibodies to Igbo-Ora virus by the haemagglutination-inhibition test. Prevalence in the human population (3.6%) was lower than that in the animal population (24.5%) in the same locality. No antibodies were detected in persons less than 20 years of age; the highest prevalence of antibodies was found in those above 40 years old. Among the animal species examined, cattle showed the highest prevalence (40%) of antibodies to Igbo-Ora virus. The potential hazard of the virus to human health is discussed.

1987 yellow fever epidemics in Oyo State, Nigeria: a survey for yellow fever virus haemagglutination inhibiting antibody in residents of two communities before and after the epidemics

A survey for yellow fever haemagglutination inhibiting antibody was carried out before and after the 1987 yellow fever epidemics in Nigeria in two localities in Oyo State, namely: Ibadan and Ogbomosho. A total of 129 sera were collected from the two localities before the epidemic. The overall prevalence of yellow fever HI antibody was 37%. A breakdown of positive sera showed that 30/100 and 18/29 sera tested in Ibadan and Ogbomosho respectively were positive. There was a higher prevalence of HI antibody in males (43%) than in females (32%). Of the 48 yellow fever positive sera 23(47%) contained HI antibody to West Nile and 26(52%) to Potiskum viruses. Following the epidemic and the subsequent mass vaccination campaign with the 17D yellow fever vaccine, 200 sera were randomly collected from the same localities. The overall prevalence of yellow fever HI antibody was 67%. The percentage of positive sera in the individual locality was 63% in Ibadan and 73% in Ogbomosho. No statistical difference was observed in the prevalence of yellow fever antibody in both sexes following the yellow fever vaccination campaign (P greater than 0.05). Tests on yellow fever HI antibody positive sera collected after the vaccination campaign showed that 74% and 82% were positive for West Nile and Potiskum HI antibody respectively. Results of this study showed that despite the massive antiyellow fever vaccination campaign there was still a high percentage of seronegative persons in the two communities.