hence , t. pallidum screening is not carried out on donated units of blood before allogeneic transfusion despite world health organization ( w.h.o . ) recommendations . however , in some extreme emergencies , some donated units of blood that has not been previously screened for syphilis might not be banked at all before transfusion , thereby , putting the recipient at high risk of syphilis infection . every year , millions of people are exposed to avoidable , life - threatening risks through the transfusion of unsafe blood . as per a global database , 6 million of 81 million units of blood collected an - nually in 178 countries are not screened for trans - fusion - transmissible infections . the provision of safe and efficacious blood and blood components for transfusion or manufacturing use involves a number of processes , from the selection of blood donors and the collection , processing and testing of blood donations to the testing of patient samples , the issue of compatible blood and its administration to the patient . there is a risk of error in each process in this  transfusion chain  and a failure at any of these stages can have serious implications for the recipients of blood and blood products . thus , while blood transfusion can be life - saving , there are associated risks , particularly the transmission of blood - borne infections . the microbial agents of importance to blood transfusion services are those that are transmissible by blood transfusion and can cause morbidity and mortality in recipients . in order to be transmissible by blood , the infectious agent or infection usually has the following characteristics : presence in the blood for long periods ; sometimes in high titers , stability in blood stored at 4c or lower , long incubation period before the appearance of clinical signs , asymptomatic phase or only mild symptoms in the blood donor , hence not identifiable during the blood donor selection process . donated blood is tested by many methods , but the core tests recommended by the world health organization are these four : hepatitis b surface antigen , antibody to hepatitis c , antibody to hiv ; usually subtypes 1 and 2 , serologic test for syphilis . who reported in 2006 that 56 out of 124 countries surveyed did not use these basic tests on all blood donations . syphilis is a sexually transmitted infection ( sti ) caused by the treponema pallidum spirochete . the route of transmission of syphilis is almost always by sexual contact , although there may be congenital syphilis via transmission from mother to child in - utero . syphilis may also be transmitted via blood and blood products , and intravenous drug use . if not treated , syphilis can cause serious effects such as damage to the aorta , brain , eyes , and bones . in some cases syphilis has also acquired a new potential for morbidity and mortality through association with increased risk for hiv infection . this will make it increasingly difficult to get safe blood because of this blood borne infection . the aim of this study was to determine the survival time of treponema pallidum in banked blood with the objective of evaluating the sero - prevalence of treponema pallidum infection among wistar rats inoculated with the treponemes - blood mixture . this study was carried out in the biomedical sciences department of the ladoke akintola university of technology , ogbomoso between the 21 of april and 5 of may , 2010 . the rats used in this research were male wistar rats weighing 200 g to 230 g . before rats were used , their sera was tested by the venereal disease research laboratory test and found to be nonreactive . the virulent nichols strain of t. pallidum used throughout this work was obtained from a research laboratory . large pools were maintained frozen and were used to inoculate rats as a source of treponemes for experimental work . donor blood was obtained from the blood bank department of the ladoke akintola university teaching hospital , osogbo . two groups of the rats ( group a and b ) were inoculated in both testes with 0.5ml of artificially infected donor blood ( final density of nichols treponemes : 510 /ml ) stored at 4c for various periods of time . there were nine pairs of rats in each group , except group b which had but four pairs . the experimental protocol in group a , a pair each of rat was injected every 12 hours , starting at 0 hr , up to a maximal storage time of 96 hr . in group b , each pair of rats was innoculated after 72 , 120 , 192 and 336 hours of storage of the treponemes - blood mixture . group c which was a control group was injected with blood only , while group d rats were injected with heat - killed treponemes suspended in blood every 12 hours respectively . each plasma sample was screened for t. pallidum specific antibodies at room temperature using syphilis ultra rapid test strip [ acumen diagnostics inc . , the syphilis test strip was removed from the pouch , each strip per blood sample ( plasma ) , 2 drops ( approximately 50l ) was vertically transferred onto the specimen pad of the test strip with the help of a dropper ( each dropper per blood sample ) , 1 drop of buffer ( approximately 40l ) was then added and timer was started immediately , the maximum line on the strip was not exceeded during application . afterwards , the strip was placed on a non - absorbent surface , and the test strips were observed for red color appearance indicating the presence of t. pallidum specific antibody in the serum . the result was reported as positive , negative , or invalid against the appropriate patient 's identification number . care was taken to ensure the test kits used in this study were not expired . the syphilis ultra rapid test strip ( whole blood / serum / plasma ) is a qualitative membrane strip based immunoassay for the detection of t. pallidum antibodies ( igg and igm ) in whole blood , serum or plasma . in this test procedure , recombinant syphilis antigen is immobilized in the test line region of the strip . after a specimen is added to the specimen pad it reacts with the syphilis antigen coated particles that have been applied to the specimen pad . this mixture migrates chromatographically along the length of the test strip and interacts with the immobilized syphilis antigen . if the specimen contains t. pallidum antibodies , a red line will appear in the test line region , indicating a positive result . if the specimen does not contain t. pallidum antibodies , a red line will not appear in this region , indicating a negative result . to serve as a procedural control , a pink line will always appear in the control line region indicating that proper volume of specimen has been added and membrane wicking has occurred . positive test result was recorded as red color which appeared both on the control ( c ) and test ( t ) bands indicating the presence of anti t. pallidum antibodies in the serum samples . invalid test result was recorded as no visible color in the test strip or a red color at ( t ) without color at ( c ) bands . in addition , statistical association between the risk factors and seropositivity was evaluated with chi square statistical test at 5% ( p<0.05 ) level of significance . each plasma sample was screened for t. pallidum specific antibodies at room temperature using syphilis ultra rapid test strip [ acumen diagnostics inc . , the syphilis test strip was removed from the pouch , each strip per blood sample ( plasma ) , 2 drops ( approximately 50l ) was vertically transferred onto the specimen pad of the test strip with the help of a dropper ( each dropper per blood sample ) , 1 drop of buffer ( approximately 40l ) was then added and timer was started immediately , the maximum line on the strip was not exceeded during application . afterwards , the strip was placed on a non - absorbent surface , and the test strips were observed for red color appearance indicating the presence of t. pallidum specific antibody in the serum . the result was reported as positive , negative , or invalid against the appropriate patient 's identification number . care was taken to ensure the test kits used in this study were not expired . the syphilis ultra rapid test strip ( whole blood / serum / plasma ) is a qualitative membrane strip based immunoassay for the detection of t. pallidum antibodies ( igg and igm ) in whole blood , serum or plasma . in this test procedure , recombinant syphilis antigen is immobilized in the test line region of the strip . after a specimen is added to the specimen pad it reacts with the syphilis antigen coated particles that have been applied to the specimen pad . this mixture migrates chromatographically along the length of the test strip and interacts with the immobilized syphilis antigen . if the specimen contains t. pallidum antibodies , a red line will appear in the test line region , indicating a positive result . if the specimen does not contain t. pallidum antibodies , a red line will not appear in this region , indicating a negative result . to serve as a procedural control , a pink line will always appear in the control line region indicating that proper volume of specimen has been added and membrane wicking has occurred . positive test result was recorded as red color which appeared both on the control ( c ) and test ( t ) bands indicating the presence of anti t. pallidum antibodies in the serum samples . invalid test result was recorded as no visible color in the test strip or a red color at ( t ) without color at ( c ) bands . in addition , statistical association between the risk factors and seropositivity was evaluated with chi square statistical test at 5% ( p<0.05 ) level of significance . each plasma sample was screened for t. pallidum specific antibodies at room temperature using syphilis ultra rapid test strip [ acumen diagnostics inc . , the syphilis test strip was removed from the pouch , each strip per blood sample ( plasma ) , 2 drops ( approximately 50l ) was vertically transferred onto the specimen pad of the test strip with the help of a dropper ( each dropper per blood sample ) , 1 drop of buffer ( approximately 40l ) was then added and timer was started immediately , the maximum line on the strip was not exceeded during application . afterwards , the strip was placed on a non - absorbent surface , and the test strips were observed for red color appearance indicating the presence of t. pallidum specific antibody in the serum . the result was reported as positive , negative , or invalid against the appropriate patient 's identification number . care was taken to ensure the test kits used in this study were not expired . the syphilis ultra rapid test strip ( whole blood / serum / plasma ) is a qualitative membrane strip based immunoassay for the detection of t. pallidum antibodies ( igg and igm ) in whole blood , serum or plasma . in this test procedure , recombinant syphilis antigen is immobilized in the test line region of the strip . after a specimen is added to the specimen pad it reacts with the syphilis antigen coated particles that have been applied to the specimen pad . this mixture migrates chromatographically along the length of the test strip and interacts with the immobilized syphilis antigen . if the specimen contains t. pallidum antibodies , a red line will appear in the test line region , indicating a positive result . if the specimen does not contain t. pallidum antibodies , a red line will not appear in this region , indicating a negative result . to serve as a procedural control , a pink line will always appear in the control line region indicating that proper volume of specimen has been added and membrane wicking has occurred . positive test result was recorded as red color which appeared both on the control ( c ) and test ( t ) bands indicating the presence of anti t. pallidum antibodies in the serum samples . invalid test result was recorded as no visible color in the test strip or a red color at ( t ) without color at ( c ) bands . the data generated in this study were presented with descriptive statistics . in addition , statistical association between the risk factors and seropositivity was evaluated with chi square statistical test at 5% ( p<0.05 ) level of significance . table 2 shows the syphilis formation pattern in the treatment groups . syphilis serological formation pattern in the treatment groups 14 rats ( 77.8% ) out of the 18 rats that were involved in group a developed orchitis and positive serology up to 72 hours of storage time , p<0.05 . only both 72hr rats ( 25% ) developed orchitis and a positive syphilis serology in group b. all the 18 rats ( 100% ) in the control group c and d showed neither clinical nor serological changes . the 77.8% positive serology recorded in group a was thought to be as a result of the sero - conversion that has taken place in the experimental rats , regardless of the incubation time and the temperature ( 4c ) the treponemes - blood mixture was subjected to , before inoculation . the 75% negative serology observed in group b was thought to be as a result of longer incubation period ( 72hrs ) the treponemes - blood mixture was subjected to , before inoculation time , though , 25% of the rats presented with orchitis and a positive syphilis serology . 100% negative serology was observed in groups c and d. initially , 50% of group d animals lost weight , hostile and aggressive but they later regained weight after ad - libitum feeding . while blood transfusion can be life - saving , there are associated risks , particularly the transmission of blood - borne infections . this study was therefore aimed at determining the survival time of t. pallidum in banked blood . the literature also notes that syphilis can occur in blood donors[57 ] . from this study , treponema pallidum survival in blood bank temperature the survival time of t. pallidum in this study was similar to that suggested by w.h.o . in 2009 . the 72hrs t. pallidum survival time found in this study calls for a major review of the practice of screening donor blood in nigeria . based on the results of this study , the present policy in which prospective donors are screened clinically and for only hiv and hbv infections therefore require urgent revision . on the other hand , it is a well - known fact that hiv , hbv and hcv are global infectious pathogens contributing to mortality and morbidity in all ages . hence , there should be a consensus among transfusion scientists in nigerian medical institutions on the need for routine donor screening of transfusion transmissible infections ( ttis ) like hiv 1&2 , hbv , hcv , and syphilis . there are commercially available rapid test kits to determine the serum antibodies to the aforementioned ttis . the implication of t. pallidum survival in donor blood is the risk of transmission of this pathogen to recipients of blood and blood products . this can contribute to the ever - widening pool of infection in the wider population . syphilis has also acquired a new potential for morbidity and mortality through association with increased risk for hiv infection thus making safe blood more difficult to get . it was concluded that the survival time of t. pallidum in banked donor blood lies between 72 - 120hrs in this study . comparison of our results with literature findings suggests that the experimentally found survival time could depend on the number of treponemes initially present in the donor blood . however , it is fully unclear whether infectivity in rat testes can be paralleled with infectivity in the human system . it is therefore recommended that regardless of blood banking temperature , it is required in all nigerian hospitals to screen for t. pallidum and other transfusion transmissible infections prior to allogeneic transfusion , which may help in avoiding transfusion related syphilis and its probable long - term effects .
background : every year , millions of people are exposed to avoidable , life - threatening risks through the trans - fusion of unsafe blood.aim:to determine the survival time of treponema pallidum in banked donor blood.material and methods : two groups of male wistar rats ( group a and b ) were inoculated intratesticularly with 0.5ml of artificially infected donor blood ( final density of nichols treponemes : 5105 /ml ) stored at 4c for various periods of time . in group 
 a , a pair each of the rats was injected every 12 hours , starting at 0 hr , up to a maximal storage time of 96 hr . in group 
 b , the rats were injected after 72 , 120 , 192 and 336 hours of storage of the treponemes - blood mixture . 
 group c which is a control group was injected with blood only , while group d rats were injected with heat - killed treponemes suspended in blood every 12 hours . 
 the detection of treponema pallidum igg / igm was based on the principle of double antigen sandwich immunoassay , in which purified recombinant antigens are employed sufficiently to identify antibodies to syphilis . 
 the outcomes of interest included the proportion of syphilis positive rats and the maximal survival hours of t. pallidum in banked blood.results:14 rats ( 77.8% ) out of the 18 rats that were involved in group a developed orchitis and positive serology up to 72 hours of storage time , p<0.05 . 2 rats ( 25% ) in group b developed orchitis after 72hrs of storage time . 
 all the 18 rats ( 100% ) in the control group c and d showed neither clinical nor serological changes.conclusion:it was concluded that the survival time of t. pallidum in banked donor blood lies between 72 - 120hrs in this study . 
 regardless of blood banking temperature , t. pallidum and other transfusion transmissible infections should be screened for prior to allogeneic transfusion .