Background: Over 20 million persons are infected with HTLV-I/II globally.The virus is endemic in Africa and it is also transmitted sexually. Continued identification of high risk groups is important for the control of the disease.
Objectives:To determine the prevalence of HTLV infection amongst two highly sexually active groups, pregnant women and CSWs in South Western Nigeria.
Methods: Serum samples were tested for the presence of HTLV-I/II antibodies using the Vironostika® HTLV-I/II micro ELISA system.
Results:A total of 364 serum samples collected from pregnant women, commercial sex worker (CSW) and secondary school students (control group) from Ibadan.While only 4 (5.1%) of 78 secondary school students (average age: 13years) were reactive for HTLV infection, 20 (16.7%) of 120 pregnant women (average age: 26years) and 38 (22.9%) of 166 CSWs (average age: 23years) were found to have antibodies against HTLV in their sera.The results of this study thus show that HTLV infection is active in the population although higher in pregnant women (although not statistically significant) and CSWs (p>0.05). Pregnant women and CSWs are therefore at a higher risk of HTLV transmission than other members of the population.
Conclusion: Routine screening for HTLV infection may go a long way to understanding the epidemiology of HTLV infection in Nigeria and subsequently provide tools for its prevention and control.
 Keywords: HTLV, prevalence, pregnant women, commercial sex workers, Nigeria. African Health Sciences  Vol.  7 (3) 2007: pp. 129-13

Forbi, JC

Odetunde, AB

PubMed

Forbi, J.C.

Odetunde, A.B.

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Human T-cell Lymphotropic Virus in a Population of Pregnant Women and
Commercial Sex Workers in South Western Nigeria

Forbi, J C

Odetunde, A B

AJOL - African Journals Online

African Health Sciences Vol 7 No 3 September 2007 129Human T-cell lymphotropic virus in a population of pregnantwomen and commercial sex workers in South Western NigeriaJ.C. Forbi1*, A.B. Odetunde2*1Virology laboratory, Innovative Biotech-Keffi, PO Box 30 Keffi, Nasarawa State,Nigeria 2Institute of Advanced Medical Research andTraining, University of Ibadan,NigeriaAbstractBackground: Over 20 million persons are infected with HTLV-I/II globally. The virus is endemic in Africa and it is also transmittedsexually. Continued identification of high risk groups is important for the control of the disease.Objectives: To determine the prevalence of HTLV infection amongst two highly sexually active groups, pregnant women and CSWsin South Western Nigeria.Methods: Serum samples were tested for the presence of HTLV-I/II antibodies using the Vironostika® HTLV-I/II micro ELISA system.Results: A total of 364 serum samples collected from pregnant women, commercial sex worker (CSW) and secondary school students(control group) from Ibadan. While only 4 (5.1%) of 78 secondary school students (average age: 13years) were reactive for HTLVinfection, 20 (16.7%) of 120 pregnant women (average age: 26years) and 38 (22.9%) of 166 CSWs (average age: 23years) were foundto have antibodies against HTLV in their sera. The results of this study thus show that HTLV infection is active in the populationalthough higher in pregnant women (although not statistically significant) and CSWs (p>0.05). Pregnant women and CSWs aretherefore at a higher risk of HTLV transmission than other members of the population.Conclusion: Routine screening for HTLV infection may go a long way to understanding the epidemiology of HTLV infection inNigeria and subsequently provide tools for its prevention and control.Keywords: HTLV, prevalence, pregnant women, commercial sex workers, Nigeria.African Health Sciences 2007; 7(3): 129-132*Address for correspondence:Forbi JC,Virology laboratory,Innovative Biotech-Keffi, PO Box 30 Keffi,1. Abdu Abubakar Street, GRA-Keffi,Nasarawa State, Nigeria.cforbi79@hotmail.comIntroductionHuman T-cell lymphotropic virus types I and II(HTLV I/II) are closely related yet distinct humanretroviruses that share approximately 60% of their overallnucleotide sequence1. HTLV-I has been shown to beassociated with at least two well-defined clinical entities,namely Adult T-cell leukemia/lymphoma (ATLL) andHTLV-I associated myelopathy/tropical spasticparaparesis (HAM/TSP)2,3,4. HTLV-II was initiallyisolated from a patient with hairy cell leukemia but itspathogenicity is not clearly understood5. .Recently,HTLV-II has also been shown to be linked with otherneurological syndromes 6.Over 20 million persons are infected withHTLV-I/II globally7. Most are described in highlyendemic areas such as Japan, intertropical Africa, theCaribbean’s and surrounding regions. On the contrary,low HTLV seroprevalence rates are observed in non-tropical areas8,9. Several studies have reported highprevalence of HTLV infections in Africa10,11,13. It istherefore necessary to find out which group of individualsare reservoirs of the virus in the population. In Nigeria,routine diagnosis of HTLV infection is rare. This isworsened by the fact that government focuses on HIV(another retrovirus) that is presently establishing itselfin Nigeria. To date, no vaccine or drugs have been licensedfor use against HTLV infection.HTLV-I/II infections can be transmitted byvertical route (mother –to-child and breast milk), sexualintercourse and parenteral (blood transfusion andintravenous drug use)13. In Nigeria, transmission of HTLVinfection to transfused recipients and in patients withleukaemia/lymphoma are welldocumented14,15,16,17,18,19,20. Olaleye et. al.,21 had shownthat vertical transmission of HTLV infection may not bethe major route of transmission of HTLV infection inSouth Western Nigeria. On the other hand, informationon sexual transmission of HTLV infection is scanty inNigeria and we think that this might well be a very im-portant mode of transmission in Nigeria. Recently, aNigerian-born CSW with ATL exported HTLV infec-tion to Italy19. Identifying high risk groups remains oneof the greatest opportunity to reduce the spread of thevirus. This study was therefore designed to determinethe prevalence of HTLV infection amongst two highlysexually active groups, pregnant women and CSWs inSouth Western Nigeria.African Health Sciences Vol 7 No 3 September 2007 130Subjects and MethodsStudy area and populationThis study was carried out among pregnantwomen attending the antenatal clinic of the Oyo statehospital, Oyo and CSWs from brothels in Ibadanmetropolis. Only females were eligible to participate inthe study. After explaining the purpose and importanceof the study to the clients, blood samples were collectedby venepuncture from individuals who agreed to be bled.Blood samples were also collected from sex-matchedcontrol group consisting of students from a secondaryschool in Ibadan. These students were chosen as a controlgroup since it is believed that this group of people arenot as sexually active, hypothetically conferring on thema lower risk of acquiring HTLV-infection.HTLV- I/II MicroELISA SystemTo detect antibodies against HTLV-I/II, sera were testedwith a commercial enzyme immunoassay in which thesolid phase (micro wells) were coated with a purifiedHTLV-I viral lysate, a purified HTLV-II viral lysate and arecombinant HTLV-I p21E antigen (Vironostika HTLV-I/II MicroELISA system: Biomerieux, Inc, Durham,North Carolina; Lot No. 43-01808; sensitivity = 100% ,specificity = 99.95%). The plates were read at awavelength of 450nm. Reactive and non-reactive resultswere then determined according to the instructions ofthe manufacturers.Statistical AnalysisThe prevalence of HTLV-I/II antibodies in the differentgroups were compared using the chi-Square test at 95%confidence level with the aid of the SigmaStat statisticalSoftware Version 2.0 running on a window NT platform(Jandel Scientific Software, USA).ResultsSamples were collected from 120 pregnantwomen, 166 commercial sex workers (CSWs) and 78secondary school students from Ibadan/Oyo state-Ni-geria. The mean ages of the pregnant women and CSWswere 26 years and 23 years respectively. The mean age ofthe secondary school students (control group) was 13years. All participants in the study were females.Of the 120 pregnant women tested, 20(16.7%)were found to have antibodies against HTLV while 38 of166 (22.9%) CSWs were found to have anti - HTLVantibodies. Only 4 of 78 secondary school students haddetectable antibodies against HTLV in their sera.Although the prevalence of anti - HTLV antibodies washigh amongst pregnant women, that of CSWs wassignificantly higher (p<0.05). The detailed results aresummarized in Table 1 & 2.Table 1: Distribution of HTLV infection amongst pregnant women and commercial sex workers inIbadan.Groups tested NT NR %R X2,d.f=1           p-value(5% Value)Pregnant women 120 20 16.7 2.95                  p>0.05Commercial Sex Workers 166 38 22.9 5.8                    P<0.05Secondary school students 78 4 5.1 - -Key:NT: Number TestedNR: Number ReactiveTable 2: Distribution of HTLV sero-reactive cases according to ageGroups tested Age (i years)14-15 19-20 21-22 23-24 26-30 TotalPregnant women 0 4 0 10 6 20Commercial sex workers 0 2 12 24 0 38Secondary school students 4 0 0 0 0 4Total tested 4 6 12 34 6 62African Health Sciences Vol 7 No 3 September 2007 131DiscussionThe assessment of the prevalence of HTLV in-fection is important especially in endemic areas like Ni-geria because transmission of the virus could in somecases result in malignancies. In this study, we report theprevalence HTLV in two important sexually activegroups, pregnant women and CSWs in South WesternNigeria. These are a group of people who have a higherrisk of contacting, spreading and maintaining the virus inthe community. We used an ELISA which is both sensi-tive and specific (99.89-100%) and which is a methodapproved by the Food and Drug administration (FDA)for the routine screening of blood donors for HTLVantibodies 20.The result of this study shows that 22.9% ofCSWs who participated in the study had antibodies toHTLV (p<0.05). Also, 16.7% of the pregnant womenwere sero-reactive. This is high although not statisticallysignificant. This is one of the highest percentages of HTLVsero-reactivity ever recorded in Nigeria and this indicatesa high prevalence of the virus in the population (Table1). These finding confirms the strong suggestions byOlaleye et. al.,21 that HTLV infection is predominantlytransmitted by horizontal route in Nigeria. The highprevalence of infection seen in CSWs when comparedto blood donors and patients with leukemia in Nigeriasuggest that this group of people are actively involved inthe maintenance and transmission of the virus in the po-pulation. Counseling and screening of blood donors andpregnant women for evidence of HTLV infection couldbe justified due to possible interaction of high riskindividuals with the general population.Interestingly, 5.1% of the control group wasHTLV sero-reactive (Table 1). This supports the fact thatHTLV infection is endemic in Nigeria although less inthis group when compared to the highly sexually activegroups. Since unfortunately at the current time no vac-cines or treatment are available for those with HTLVinfection, then knowledge of a person’s antibody statusis only helpful from a preventive point of view tosubstantially reduce the rate of spread of the virus.Mothers who are reactive could be advised not tobreastfeed their infants and the use of condoms can beexpected to reduce the spread of the virus amongpersons engaging in sexual intercourse with an infectedpartner.The lower prevalence in the control groupcould also be attributable to the lower ages of the parti-cipants in this group (14-15 years). The age relatednessof HTLV infection needs a closer look. Previous studieshave shown that HTLV infection increases with age from20 to 40 years14, 22. The increased age may be an indica-tion of greater sexual involvement, which is a major modeof transmission of the virus (Table 2). Perhaps in thefuture, it would be necessary and helpful to screen virginsand celibates for HTLV infection to further prove thispoint, as even secondary school students are now knownto be sexually involved although not probably as muchas pregnant women and CSWs. This will further betterdefine the epidemiology of the virus in Nigeria.We have recorded one of the highest prevalenceof HTLV infection in Nigeria among pregnant womenand commercial sex workers and it is obvious that thesegroups of people serve as reservoirs of HTLV in Nigeria.Increasing attention should be given to the routinescreening of HTLV in Nigeria as this can make the greatestcontribution to reducing the risk of this infection andalter its course in humans.LimitationsThe assay used was not designed to discriminate betweenHTLV-I and II infection but it was highly specific andsensitive to detect infection in the same microelisa well.Secondly, confirmatory test for HTLV-I/II was notreadily available to us. Despite this limitation, HTLVELISA has been known to be very sensitive, specific andhighly reproducible.AcknowledgementWe are grateful to Mr. Aboderin of the Oyo State Hospi-tal, Oyo, for providing the sera from pregnant women.References1 Gallo RC. Human Retroviruses: a decade of discovery andlink with human disease. Journal of Infectious Diseases 1991.164:235-432 Blattner WA. Epidemiology of HTLV-1 and associateddisease: In Blattner WA (ed): Human Retrovirology HTLV.New York: Raven Press 1990, 252-633 Costa CM, Goubau P, Liu HF, Vandamme AM, da-CunhaFM, Santos TJ, Desmyter J, Carton H. HTLV-negative andHTLV-1 like positive tropical spastic paraparesis inNorthern Brazil. AIDS Research and Human Retroviruses 1995.11 (2): 315-3184 Nagai M, Jacobson S. Immunopathogenesis of human T-celllymphotropic virus type-1 associated myelopathy. 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Human T-cell lymphotropic virus in a population of pregnant women and commercial sex workers in South Western Nigeria

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