Prevalence and association of human parvovirus B19V with hepatitis B and C viruses in Nigeria.

Co-infection of parvovirus B19 with hepatitis B virus has been found in patients with acute and chronic hepatitis. The clinical significance of parvovirus B19 in hepatitis B co-infected patients is still controversial. In this study parvovirus B19 antibodies and DNA were investigated in serum samples from 76 patients with HBV infection, 17 with HBV/HCV co-infection and 44 healthy controls. In the sera from patients with HBV infection, anti-B19V IgM and IgG antibodies were detected in 24/76 (32%) and 25/76 (33%), in 6/17 (35%) and 8/17 (47%) of HBV/HCV co-infected patients, and in 14/44 (32%) and 12/44 (12%) of a non-hepatitis healthy controls, respectively. B19V DNA was detected in 8/76 (11%) of patients with HBV infection and in 3/17 (18%) of patients with a HBV/HCV co-infection, and in 4/44 (9%) healthy controls. The occurrence of parvovirus B19 DNA was significantly higher in patients with symptomatic HBV 4/20 (20%) compared to asymptomatic HBV carrier 4/56 (7%) (P<0.05). Ten of the positive B19V DNA sequences belonged to B19V genotype 1 while two belonged to genotype 3. The results of this study showed a significant difference in the prevalence of parvovirus B19 DNA in symptomatic HBsAg positive as compared to asymptomatic HBsAg positive individuals; however, the conclusion that parvovirus B19 infection increased the frequency of liver disease was not supported. Long-term longitudinal studies are, however, required to determine the synergistic effect of parvovirus B19 infection in HBV or HBV and HCV co-infected persons.

Absence of HIV-1 and HIV-2 seroconversions in a cohort medical students in a Nigerian medical school.

A cohort of 70, HIV-1 and HIV-2 seronegative medical students were followed up for 30 months, after which 65 were retested for HIV antibody. None of the students was infected by HIV during the period of study. A questionnaire survey carried out showed that all the students had a very good knowledge of HIV, its mode of transmission, control and prevention. Most of the students have never had sex or had a single sex partner and used condoms always or most of the time during sexual intercourse.

Rabies and antirabies immunization in South Western Nigeria: knowledge, attitude and practice.

Factors responsible for the continued endemicity of rabies in Nigeria were determined by carrying out a knowledge, attitude and practice study among residents of Osun State. Structured questionnaires were administered to 679 individuals comprising students, traders and civil servants. Only 33.4% of the respondents knew rabies could be prevented by vaccination, while 38.7% believed that the infection could be treated with herbs. Of the 387 victims of dog bite, 240 (62%) never sought prophylactic postexposure treatment. Of the 10 people who received postexposure treatment, only one received the appropriate treatment consisting of washing, disinfection of wounds, tetanus toxoid and complete antirabies immunization.

Preliminary studies on the use of solid-phase immunosorbent techniques for the rapid detection of Wesselsbron virus (WSLV) IgM by haemagglutination-inhibition.

Serum samples from 446 randomly selected persons belonging to different age groups and locations in Nigeria were tested for the presence of WSLV IgM using the flavivirus haemagglutination-inhibition (HI) test adopted to the solid-phase immunosorbent technique (SPIT). 61 (14%) persons had IgM to WSLV only, while 9 (2%) persons had heterologous IgM to WSLV and two other flaviviruses, namely yellow fever and Uganda S viruses. There was a high prevalence of IgM in people of younger age groups than those in older groups. The majority of the IgM positive sera (67 (96%) of the 70 positive sera reacted to high titres (>21:80). With the conventional HI tests, 314 (70%) of the total sera tested had HI antibodies to one or more flaviviruses (yellow fever, West Nile, Potiskum, Zika and Uganda S) out of which 305/314 (97%) had antibodies to 3 or more flaviviruses used in the tests. Although SPIT may not be as sensitive as the conventional HI test, it was found to be more specific and could be adopted for the detection of early WSLV infections in flavivirus hyperendemic environments.

Antigenic relatedness of selected flaviviruses: study with homologous and heterologous immune mouse ascitic fluids

A relacao antigenica de 9 Flavivirus, febre amarela (YF), Wesselsbron (WSL), Uganda S (UGS), Potiskum (POT), West Nile (WN), Banzi (BAN), Zika (ZK), Dengue tipo 1 (DEN-1) e Dengue tipo 2 (DEN-2), foi avaliada por reacao de inibicao da hemaglutinacao cruzada (cross-HI) e reacao de fixacao do complemento cruzada (Cross-CF) entre cada um dos virus e seu fluido ascitico homologo em camundongos. Medias de titulos foram calculadas usando os titulos heterologos e homologos. Reacoes cruzadas CF revelaram maiores variacoes antigenicas entre virus do que reacoes cruzadas HI. Nao houve variacao antigenica significativa entre virus WSL, POT e YF usando cada um dos metodos. Todavia, diferencas definidas da antigenicidade foram observadas entre eles e os virus UGS, BAN e ZK. Nao existiram diferencas significativas entre UGS, BANe ZK ou entre DEN-1 e DEN-2. A relacao sorologica entre Flavivirus e importante para se estabelecer o diagnostico e a epidemiologia destas infeccoes na Africa

Antigenic relatedness of selected flaviviruses: study with homologous and heterologous immune mouse ascitic fluids.

The antigenic relationship of 9 flaviviruses, Yellow fever (YF), Wesselsbron (WSL), Uganda S (UGS), Potiskum (POT), West Nile (WN), Banzi (BAN), Zika (ZK), Dengue type 1 (DEN-1) and Dengue type 2 (DEN-2), was assessed by cross-haemagglutination-inhibition (Cross-HI) and cross-complement fixation (Cross-CF) reactions between each of the viruses and their homologous immune mouse ascitic fluids. Titre ratios were calculated using the heterologous and homologous titres. Cross-CF reactions revealed wider antigenic variations among viruses than Cross-HI reactions. There was no significant antigenic variation between WSL, POT and YF viruses using either of those methods. However, definite differences in antigenicity were observed between them and UGS, BAN and ZK viruses. There were no significant differences between UGS, BAN and ZK or between DEN-1 and DEN-2. The serological relationship among flaviviruses is important in establishing diagnosis and epidemiology of these infections in Africa.

Acute bronchiolitis in tropical Africa: a hospital-based perspective in Ibadan, Nigeria.

In a 30-month prospective study of severe acute lower respiratory infections in hospitalized pre-school Nigerian children, acute bronchiolitis was diagnosed in 67 cases; 19 (28.4%) and 2 (3.0%) of these had concomitant pneumonia or croup, respectively. The peak prevalence was in the wet (rainy) season (May-October). The male/female (M:F) ratio in infants < or = 6 months was 2.9:1, differing significantly from the 1.1:1 in older subjects (P = 0.04). None of the subjects had severe malnutrition. Neither a high fever (> or = 39 degrees C), nor tachypnea on admission was significantly correlated with co-existing pneumonia. Of the 29 subjects in whom it was possible to explore viral immunofluorescence studies and/or serodiagnosis, we identified 26 viral identifications in 18 (62.1%) cases; 6 (20.7%) had > or = 2 viruses. Respiratory syncytial virus was identified in 11 (38.0%) of the 29 cases, and parainfluenza virus (PIV) types 1, 2, and 3 in 10 (34.5%). PIV type 3 accounted for 7 cases, including 3 with bacteremia. Bacterial isolates were made in 9 (21.4%) of 42 blood cultures and in the only lung aspirate; Staphylococcus epidermidis and Staphylococcus aureus accounted for 4 and 3 cases, respectively. Although bacteremia was 2.9 times more common in cases with co-existing pneumonia or croup, the respective frequency of virus-positive cases and that of bacteremia was not significantly different between cases with bronchiolitis alone and those with associated pneumonia or croup. No deaths were recorded, but subjects aged > 6 months had a significantly shorter hospital stay than those < 6 months old (P = 0.02). Despite the limited sample size, our findings reflect the etiological importance of the paramyxoviruses and the seasonal pattern of bronchiolitis in tropical 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.

Respiratory syncytial virus--associated lower respiratory diseases in hospitalised pre-school children in Ibadan.

An analysis of the features of lower respiratory diseases (LRD) associated with Respiratory Syncytial Virus (RSV) in 21 children aged 1-23 months, indicated that the clinical features did not differ appreciably from those described for LRD due to other infective agents. It was however, remarkable that none of the children was grossly malnourished, neither was there any death. The final respiratory diagnoses were bronchiolitis alone (6 cases), bronchopneumonia (6 cases), empyema/pleural effusion (3 cases, including one with bronchopneumonia), lobar pneumonia (3 cases, including one with associated bronchopneumonia). Streptococcus pneumonia and Klebsiella pneumoniae respectively, were isolated from blood culture in the two cases with lobar pneumonia alone. One child had laryngotracheobronchitis (croup) alone and another, croup associated with bronchiolitis and bronchopneumonia. Radiologically, the single most common lesion was patchy consolidation (8 cases) followed by hyper-inflation (6 cases); in one case, there was no observable lesion on the chest radiograph. All the 6 children who had bronchiolitis alone were aged 12 months and below, and were well nourished; conversely, 8 of the 12 children with pneumonia alone or in addition to other lesions and both children with pleural effusion, were older than 12 months and underweight. Other viral agents were identified in 8 (38%) of the cases. Complications included heart failure in 4 cases and a combination of anaemia and heart failure in one child with empyema. In a child with symptom complex and radiological features suggestive of acute obstructive lower respiratory infection with immunofluorescence evidence of RSV infection, age and nutritional status are important factors in determining the need for antibiotic therapy pending the outcome of bacterial cultures.

Dengue type 1 epidemic with haemorrhagic manifestations in Fiji, 1989-90.

A dengue type 1 epidemic occurred in Fiji between July 1989 and July 1990. Virus isolation in C6/36 cell cultures and Toxorhynchites mosquitos yielded 36 strains. Of the 3686 cases recorded by the Ministry of Health, 60% involved indigenous Fijians and 37%, Indians. A house-to-house survey revealed that a large majority of patients had classical dengue symptoms and 8% reported haemorrhagic manifestations. Among the children and adults hospitalized for dengue, 43% had haemorrhagic manifestations, including epistaxis, gingival bleeding, haematemesis, melaena and haematuria. A total of 15 patients with haemorrhagic manifestations and/or shock died, 10 of whom were aged 0-15 years; the diagnoses were confirmed in four cases by virus isolation or serology.

PIP: Researchers reviewed the medical records of all cases of dengue and dengue-like illness in Fiji since 1971. During March-April 1990, in Fiji, interviews were conducted with 426 occupants of 81 randomly selected houses in Suva and its surrounding areas to examine the relationship between the incidence of true dengue and dengue-like illnesses and the reported incidence. 60% of the persons interviewed were Fijians and 31% were Indians. Health workers collected blood samples from acute cases. 36 strains of dengue 1 virus was isolated. A fever lasting more than 3 days accompanied by at least one of the following symptoms denoted dengue or dengue-like illness: headache, joint pains, muscle pains, rash, epigastric discomfort, and bleeding. There was an outbreak of clinical dengue 1 during 1989-1990 involving 3686 cases. The 1975 outbreak involved 1600-2400 cases of dengue hemorrhagic fever. The 1989-1990 incidence was higher among Fijians than Indians (60% vs. 37%). The dengue epidemic peaked in November 1989 (about 900 cases). The rate of dengue hemorrhagic fever was 8% (15 cases). Hemorrhage manifestations included nosebleeds (8 persons), gingival bleeding (2), vomiting of blood (2), blood in the urine (3), and passage of dark stools stained with blood (3). The case fatality rate was 8%. Hemorrhages of the stomach and lungs occurred in most fatal cases. 10 of the 15 fatal cases were aged 10-15 years. 182 (43%) of the respondents in the household survey had reported dengue-like illness in the last 6 months. Children were more likely to have had dengue than adults (51% of 0-9 year olds and 61% of 10-19 year olds vs. 32-33% for all other age groups). Among hospitalized dengue cases, 43% experienced hemorrhages.

Haemagglutination-inhibiting antibodies against influenza A and B in human sera collected from five ecological zones in Nigeria.

The prevalence of antibodies to the haemagglutinins of two influenza A subtype, H1N1 and H3N2 and influenza B in sera collected from 1986 to 1988 from persons of different ages and from 10 locations in 5 ecological zones of Nigeria was determined. The levels of influenza antibodies in the sera varies with age and ecological zones of the country. A total of 1,022 sera were tested, of which 732 (71.6%) were positive for influenza antibodies. The prevalence of antibodies at titre 1:10 varied between 31.1% in the derived savannah and 94.4% in the swamp forest. The prevalence in the other zones were: rain forest 63.9%, guinea savannah 86.0% and 78.0% in sudan savannah. Reactors with the two influenza A subtypes antigens were more than reactors with influenza B antigens in the country. Antibody levels to influenza A subtypes varied between and within zones. Although there was no significant difference a (P greater than 0.05) in the overall prevalence of antibodies to the two subtypes, more sera had haemagglutination-inhibiting antibody to H1N1 subtype than H3N2 subtype in all the zones except in the rain forest. Prevalence of antibodies to influenza viruses increased with age in all the zones. Overcrowding in big cities and dry, dusty harmattan weather of the northern parts of the country are considered as possible risk factors in the epidemiology of influenza in Nigeria.

West Nile Complement Fixing antibodies in Nigerian domestic animals and humans.

A survey for West Nile Complement Fixing (CF) antibody was carried out in humans and domestic animals in Nigeria. Human sera were obtained from two communities namely Ibadan and Ogbomoso but animal sera were collected from Ibadan and Maiduguri. The overall CF antibody to West Nile virus in the two localities surveyed was 65%. Of 170 persons tested, 53% and 75% were positive in Ibadan and Ogbomoso respectively. Antibody prevalence increased with age in both communities. Tests for antibody against other flaviviruses revealed that monotypic complement fixation reactions were found frequently in young people, but broadly reacting sera were common among the older age groups. Sex distribution of West Nile CF antibody showed that 49/82 (60%) of females and 62/88 (75%) of males had West Nile CF antibody. Tests on animal sera showed that 33% contained CF antibody to West Nile virus. Prevalence of CF antibody in different animal species was 62% in camels, 4% in cattle and 0% in goats.

Haemagglutination-inhibiting (HI) antibodies against strains of influenza A virus in horse and pig sera in Nigeria.

Sera from horses and pigs obtained from Lagos and Ibadan respectively were examined for haemagglutination-inhibiting (HI) antibodies to two strains each of H3N2 and H1N1 subtypes of influenza A virus. More horse sera had HI antibodies to the H3N2 than the H1N1 strains while pig sera reacted almost equally with strains of both subtypes. All the horse sera had HI antibodies to the two strains of H3N2 subtype (A/Mississippi/1/85 and A/Leningrad/360/86), while 87% and 14% of the horses examined were positive to A/Taiwan/1/86 and A/Chile/1/83. On the other hand HI antibody prevalence to the two subtypes in pigs are as follows, for H3N2 A/Mississippi/1/85 (86%), A/Victoria/3/75 (94%); for H1N1 A/Chile/1/83 (87%) and A/Taiwan 1/86 (79%). Analysis of the data by the Chi-square test showed significant difference between the prevalence of HI antibodies to the influenza A virus strains in horse sera examined while there was no significant difference between HI antibody prevalence to the four strains in pigs. The study shows that horses and pigs circulate influenza A virus in Nigeria and may serve as origin of human epidemics.

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.

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.

Susceptibility of laboratory and domestic animals to experimental infection with Potiskum virus.

The biological characteristics of Potiskum virus, a hitherto undescribed virus isolated in Nigeria from the liver of a giant rat (Cricetomys gambianus), were studied by experimental infections of laboratory and domestic animals. The laboratory animal hosts used included mice, rats, rabbits and chicks. Suckling and weaning mice succumbed to fatal infection when infected with Potiskum virus by intracerebral or intraperitoneal routes. Infected mice had high titres of virus and mild histopathological lesions which were confined to the brain. Chicks also developed a fatal disease following subcutaneous or oral infections with Potiskum virus. In contrast, albino rats and rabbits failed to succumb to overt disease by subcutaneous and intraperitoneal routes of inoculation. Albino rats did not develop antibody but rabbits developed haemagglutination inhibiting, neutralising and complement fixing antibodies.

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.

Complement fixing antibodies against arboviruses in horses at Lagos, Nigeria.

Sixty-two sera horse collected from two stables at Lagos, Nigeria, were tested for complement fixing antibody to 8 arbovirus antigens; Chikungunya, Igbo-Ora, Yellow fever, Wesselsbron, West Nile, Potiskum, Uganda S and Rift Valley fever. Ten per cent of the horse sera examined contained CF antibody to one or more of the test antigens and indicated considerable arbovirus activity in the two stables. Reactions with flavivirus antigens were most common and the highest antibody titres were obtained with Wesselsbron and Yellow fever viruses. Eleven per cent of the sera tested reacted with alphavirus antigens while 10 per cent were positive for Rift Valley fever virus CF antibodies.

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.