Syphilis serology in HIV-positive and HIV-negative--论文代写范文精选

梅毒由梅毒螺旋体引起的,是主要的性发病率,像其他性传播感染,溃疡性增强的性传播使人类免疫缺陷。梅毒控制很大程度上只能由富裕的人控制,在许多发展中国家它仍然是一个悲剧性的和实质性的问题,包括尼日利亚。下面的paper代写范文继续进行详述。

Abstract
Syphilis has acquired new potential for morbidity and mortality through association with increased risk for HIV infection. Case-control survey was conducted using Rapid Plasma Reagin test and confirmatory Immunochromatographic test among HIV-positive (cases) and HIV-negative (control) Nigerians. A total of 35(14.0%) of 250 HIV-positive and 5(2.0%) of 250 HIV-negative individuals studied were seropositive for syphilis.

Introduction
Sexually transmitted diseases (STDs) are a major global cause of infertility, long-term disability and death with severe medical and psychological consequences for millions of men, women and infants.(1) Syphilis, caused by the bacterium Treponema pallidum, is a major STD which remains an important cause of morbidity and is associated, like other ulcerative sexually transmitted infections, with enhanced sexual transmission of human immunodeficiency virus, HIV.(2) While syphilis is largely under control in affluent part of the world, it continues to be a tragic and substantial problem in many developing countries, including Nigeria. 

Furthermore, through its association with increased risk for HIV infection, syphilis has acquired a new potential for morbidity and mortality.(3) The interaction of syphilis and HIV infection is reportedly complex.(4) Isolated case reports have suggested that coexistent HIV infection may alter the natural history of syphilis and the dosage or duration of treatment required to cure syphilis.(5,6) These anecdotal reports have led to the hypothesis that in patients co-infected with HIV and T. pallidum, cutaneous lesions may be more severe, symptomatic neurosyphilis may be more likely to develop, the latency period before the development of meningovascular syphilis may be shorter, and the efficacy of standard therapy for early syphilis may be reduced.(7) Furthermore, the genital ulcerations and inflammation caused by syphilis are implicated as cofactors making infected individuals three to five times more likely to acquire HIV if exposed to the virus through sexual contact.(8) Unless prompt diagnosis and treatment of syphilis are performed serious complications including male and female infertility may result, and in pregnancy, adverse outcomes such as stillbirth, perinatal death and serious neonatal infection may occur.(9)

There is paucity of information on syphilis serology in Nigeria as in other countries of the sub-Saharan Africa, a region where 25.4 million HIV-infected people (64% of all people with HIV) are living.(10) Available information in the region usually came from seroprevalence sentinel surveys of women attending ante-natal clinics, ANCs.(11- 13) This study was therefore designed to add to the limited body of literature on syphilis serology among HIV-positive and HIV-negative individuals in the sub-Saharan Africa.

It is worth noting that infection with HIV may not only alter the clinical presentation of syphilis, but also the performance of syphilis serologic tests. Thus the diagnosis of syphilis may be more complicated in HIV-infected patients because of false-negative and false-positive serologic results for T. pallidum.(7,24) Co-infection with HIV and syphilis however, does not generally impair the sensitivity of syphilis testing, although there are sporadic reports of absent or delayed response to nontreponemal tests.(25) In contrast, HIV infection may reduce the specificity of syphilis testing.(24,25) Although, serologic tests appear to be accurate and reliable for the diagnosis of syphilis and the evaluation of treatment response in the majority of HIVinfected patients (7), the interpretation of non-treponemal specific serological tests in a population where syphilis and HIV are endemic such as the subSaharan Africa may be encountered with difficulty due to lack of confirmatory tests and experienced personnel.(26,27) In many of such communities, the prevalence of reactive serology did not accurately reflect infectious syphilis largely because of unavailability of confirmatory tests.(28)This problem was however surmounted in this study by the use ofimmunochromatographic (IC) rapid syphilis test kits (Cal-Tech Diagnostic INC.), that served as confirmatory test and substantiated the findings. Females generally had higher rates of infection with T. pallidum than the males in this study. 

Although no statistical significant difference was observed, this was in conformity with the findings of Hwang et al.(29) who reported that women had up to 4.5% higher prevalence of T. pallidum infection than men. This was also consistent with the findings of Todd et al. (30) who also reported higher prevalence of T. pallidum infection in women (9.1%) than in men (7.5%) in a rural African population. On the contrary, a higher prevalence of T. pallidum infection was observed in males (27.5%) than in females (12.4%) in United State.(31) It is well established that syphilis in the females is less likely to be symptomatic; hence the prevalence of antibodies is usually higher among them compared to the males.(4,19) Secondly, there is generally a diminished access to health services by the females in the sub-Saharan Africa including Nigeria as in other developing countries.(32,33) 

These may explain the higher prevalence of syphilis among the females. Individuals in their third decade of life in this study were found to have relatively high rate of T. pallidum infection. This was more obvious in the HIV infected population and was not unexpected. In Nigeria individuals in their third decade of life are known to have the highest rate of infections associated with sexual activities because the group is the most sexually active age category.(14) This was supported by the findings from a similar study in Ethiopia where it was indicated that T. pallidum infection was more pronounced among the young age group of 15-24 years.(13)

It is important to state that this study was not without a few limitations. In this investigation, we have not been able to demonstrate that the presence of syphilis actually facilitated HIV infection because we were unable to establish whether syphilis infections pre-dated the HIV infections or vice versa. A more complex study to achieve this goal using immunological and molecular biologic tools is advocated. Our inability to report the different stages of syphilis among those infected, obtain sufficient socio-demographic data from subjects, and the rather limited study population size, were draw backs to the study. 

Further studies incorporating period of syphilis infection and detailed socio-demographic parameters as well as larger population size are advocated. In conclusion, this study has provided additional insights on the burden of T. pallidum infection in Nigeria. As a public health measure, the need to intensify efforts on the promotion of safer sexual behaviour particularly among adolescents and provision of effective, accessible treatment for STDs in developing countries can not be overstated. Transforming such measures into public health policy is indispensable to the success of HIV/STD interventional programmes.(paper代写)

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