CHAPTER ONE  

INTRODUCTION

1.1 BACKGROUND OF THE STUDY

Trichomonas vaginalis is an anaerobic, flagellated protozoan parasite and the causative agent of trichomoniasis. It is the most common pathogenic protozoan infection of humans in industrialized countries. Infection rates between men and women are similar with women being symptomatic, while infections in men are usually asymptomatic. Transmission usually occurs via direct, skin-to-skin contact with an infected individual, most often through sexual intercourse. The WHO has estimated that 160 million cases of infection are acquired annually worldwide. The estimates for North America alone are between 5 and 8 million new infections each year, with an estimated rate of asymptomatic cases as high as 50%. Usually treatment consists of metronidazole and tinidazole.

Sexually transmitted infections (STIs) are infections that are spread primarily through person-to-person sexual contact: anal, vaginal and oral sexual contact. According to the most recent data available of WHO estimates, that 340 million new cases of curable STIs (Syphilis, Gonorrhea,   Chlamydia   and   Trichomoniasis) occur annually throughout the world in adults aged 15 – 49 years (WHO, 2001). Considering Trichomonas Vaginalis worldwide infections, 12 million cases occur annually with a high number of 4 million cases encountered in sub-Saharan Africa. Notably, Trichomonas vaginalis caused infection is believed to increase the risk of HIV transmission. Trichomoniasis is also associated with adverse pregnancy outcomes, infertility,  postoperative infections, and cervical neoplasia (Soper, 2004). Trichomoniasis is the major   problem   in developing countries, where parental testing and antibiotics use are not adequately available. According to the African Humanitarian Action (AHA) report of July 2008, high rates of the commonly encountered sexually transmitted infections, in KRC, have been noticed by the 19 new cases of STIs, including Trichomonas vaginalis (Kiziba Refugee Camp Health Center, 2008). On the other hand, according to the recent information from CHUK laboratory, a high number of Trichomoniasis cases were observed each month among the patients visiting the health institution.

In women, the disease encompasses broad range of symptoms ranging from a severe inflammation and irritation with frothy malodorous discharge to a relatively asymptomatic carrier state. But the main clinical manifestation of trichomoniasis is vaginitis, urethritis and prostatitis. The outcome of infection with Trichomonas may be due to genetic variability of the isolates and the host immune response.

The vagina is the most common site of infection in women and the urethra (urine canal) is the most common site   of   infection    in   men.   The   parasite    is   sexually transmitted through penis-to-vagina intercourse or vulva­ to-vulva (the genital area outside the vagina) contact with an infected partner.  Women can acquire the disease from infected men or women, but men usually contract it only from infected women. Pregnant  women with trichomoniasis    may  have  babies  who  are  born  early  or with  low  birth  weight  (low  birth  weight  is less than  5.5 pounds).

Trichomonas vaginalis is an obligate parasite in that it lacks the ability to synthesize    many   macromolecules   de novo, particularly   purines, pyrimidines and many lipids.  These nutrients   are acquired   from   the vaginal   secretions   or through     phagocytosis     of    host    and    bacterial     cells.  Culture   media   for Trichomonas vaginalis therefore   need to include all the essential macromolecules, vitamins and minerals.  In particular,   serum is essential   for the growth   of trichomonads,    since it provides   lipids, fatty acids, amino acids and trace metals. In vitro, it grows optimally at a pH of 6.0-6.3, although it can also grow through a wide range of pHs, especially in the changing environment of the vagina. The presence of Trichomonas vaginalis in the vagina increases predispositions to mv seroconversion. The genital inflammation caused by trichomoniasis can increase   a woman’s   susceptibility to HIV infection if exposed to the virus. Having trichomoniasis may increase the chance that an HIV-infected woman passes HIV to her sex partner(s).

Recent   literature   documents   that women   infected during pregnancy are predisposed to premature rupture of membranes,      premature labor and    low-birth-weight infants. Further, it may amplify HIV transmission. The organism   typically   elicits   an aggressive   local   cellular immune response, with heavy infiltration   of leucocytes, even in symptom-free patients.  In addition, in about 50% of    infected women, punctate hemorrhages can be observed. In an HIV-negative person, there are target cells available, as also access to blood   stream.

In an mv­positive person, all this may expand the portal of exit for the virus  and  increase  shedding  of HIV-l in the  genital area. Thus, trichomoniasis may amplify   HIV-l transmission    by increasing   susceptibility   in an HIV-l­ negative   person   and the   infectiousness    of an HIV -1- positive patient.

Few   studies have been published   on Trichomonas vaginalis.

Buve  et al., (1975) confirmed  that the risk of Trichomonas vaginalis  is higher  in women  reporting  a greater  lifetime  number  of sexual  partners  in those with poorer  education  levels  and in women  with alcohol  dependency  while  McClelland   et al. reported  that the infection  was also more  common in   women    with    concomitant     cervicitis    or   bacterial vaginosis.  On the other hand, the use of condoms and progesterone-only contraceptive methods (depot­ medroxyprogestrone acetate or N orplant) was found to be associated with a lower risk of infection in a multivariate analysis model.

Prevention   of trichomoniasis   has not been a priority due   to   lack   of   understanding     of   its   public    health implications   and lack of resources. For long it has been considered a ‘minor’ STD. It has been seen that women infected during pregnancy are predisposed to premature rupture of membranes, premature labor and low­birth-weight infants. Further, it may amplify mv transmission. The natural history of this organism, including its often symptomless nature and protracted carriage, play an important role in HIV transmission dynamics, especially where heterosexual behaviours and a high prevalence of mv obtain.  The pregnant women infected with this parasite may be at risk of an adverse birth out comes such as premature rapture of membranes, premature labour, low birth weight, and post – abortion or post-hysterectomy infection, as well as infertility and enhanced predisposition to neoplastic transformation in cervical tissues. As with other sexually transmitted infections, the Trichomonas infection can increase the risk of transmission of HIV infection.

Transmission of Trichomonas Vaginalis to neonates during passage through an infected birth canal is also possible. In the foetus and the neonates, complications such as abnormalities of the major organ systems as well as infections in form of pneumonia and conjunctivitis may also occur. Neonatal infection is infrequently reported, but has been noted to cause urinary tract infection and vaginitis in infants. In addition, i infants   with   Trichomonas vaginalis c u l t u r e d   f r o m nasopharyngeal secretions have been reported to present with significant respiratory distress.

Trichomonas vaginalis can be isolated in vaginal, prostatic or urethral secretions, semen and urine of infected individuals. The most commonly employed diagnostic methods are direct microscopic examinations of wet mount preparations (with a sensitivity of 38% – 82%), and culture techniques. Combination of both wet mount examination and culture has been recommended as being more effective in establishing diagnosis than either one alone. Direct examination of wet mount preparation of clinical specimen is the most rapid and least expensive technique for identifying Trichomonas vaginalis, hence the most commonly used. This method has however been reported insensitive for the diagnosis of the disease, particularly in male patients. Other methods include antigen detection methods, plastic envelope method, in-pouch system, cell culture, staining techniques, serological and DNA techniques.

In Nigeria, there are some documented reports on the prevalence of Trichomonas infections among women, students, Commercial sex workers and in pregnant women, but no similar study on pregnant women have been done in our region (northeastern Nigeria) and possibly only one in the northern part of Nigeria.

1.2 OBJECTIVES OF THE STUDY

i.        To determine the prevalence of Trichomonas vaginalis among pregnant woman according to their age.

ii.        To isolate and identify the causative parasite.

iii.        To determine the prevalence of Trichomonas vaginalis by marital status of the pregnant women.

iv.        To recommend the possible ways of controlling and preventing the spread of the parasite via fomites, mother to child and sex partners.

1.3 PURPOSE OF THE STUDY

This study was aimed to determine the prevalence of the Trichomonas vaginalis among pregnant women attending antenatal clinic in general hospital Gboko.

1.4 STATEMENT OF THE PROBLEM

Trichomonas vaginalis has neither been the focus of intensive study none of active control program and the negligent is likely a function for relatively mind of the disease.