Vertical Transmission of Syphilis With Control Treatment

Vertical Transmission of Syphilis With Control Treatment

Zalak Ashvinkumar Patel, Nita H. Shah
DOI: 10.4018/978-1-6684-6299-7.ch010
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Abstract

Syphilis is a sexually transmitted disease having different signs and symptoms with four main stages, namely primary, secondary, latent, and tertiary. Congenital (vertical) transmission of syphilis from infected mother to fetus or neonatal is still a cause of high perinatal morbidity and mortality. A model of transmission of syphilis with three different ways of transmission, namely vertical, heterosexual, and homosexual, is formulated as a system of nonlinear ordinary differential equations. Treatment is also incorporated at various stages of infection. Total male and female population is divided in various classes (i.e., were susceptible, exposed, primary and secondary infected, early and late latent, tertiary, infected treated, latent treated, infected child [newborn], and treated infected child [at birth time]). Stability of disease-free equilibrium and endemic equilibrium is established. Control treatment is applied. It is observed that safe sexual habits and controlled treatment in each stage including pregnancy are effective parameters to curb disease spread.
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Introduction

Syphilis is a sexually transmitted disease caused by infection from bacteria Treponema pallidum (T. pallidum). Treponema pallidum is a spirochete bacterium usually transmitted by sexual contact through exposure to mucocutaneous syphilitic lesions. Wright and Jones (2003) have observed that in body fluid the infecting organism starts to replicate locally. As per WHO (2007) report, annually 12 million active infections of syphilis are getting reported. According to CDC (2010) report, there were total 13,774 cases of primary and secondary syphilis reported during 2010. Values et al. (2000) have reported that about 30 to 50% of individuals suffering from primary or secondary syphilis are at serious risk of spreading disease through sexual contacts. They also have observed that more than 80% of women with syphilis are in their reproductive (20 to 35 years old) age which causes high risk of congenital transmission. Walker and Walker (2002) have observed that each year high numbers of pregnancies are getting badly affected in all over world and yearly around 4,60,000 pregnancies end in abortion and 2,70,000 babies born prematurely or with low birth weight because of maternal syphilis. As per CDC (2010) report, rates of female and congenital syphilis were increased during 2005-2008 in the USA. In 2008, WHO estimated that 1.9 million pregnant women had active syphilis. Stolte et al. (2001), Simms et al. (2005), Heffelfinger et al. (2007) and Read et al. (2015) have reported revival of syphilis amongst homosexual male population in early 2000 even though overall decrease is reported from 1990.

In 2006, lifetime medical cost per case of syphilis was estimated as $572. Chesson et al. (2008) observed that the treatment cost per case could get increased in case of congenital infection. Blandford and Gift (2003) suggested early stage treatment to reduce the cost per case as early stage treatment is less expensive than treatment for later stage disease.

Dynamics of Syphilis Amongst Adults

After infection in humans, syphilis thrives through multiple stages if not treated. As per Garnett et al. (1997) after inoculation, first the exposed stage of an average 28 days executes in which individuals remains infected but not infectious. Garnett et al (1997), Singh et al. (1999) and LaFond et al. (2006) observed that the primary infected stage, characterized by a single painless chancre at the place of inoculation lasts up to an average 46 days of its (chancre) appearing to heal after the exposed period. The primary infected untreated patients progresses to secondary syphilis, characterized by multiple symptoms, like copper coloured skin lesions that tend to be universally distributed on whole body, the soles with painless lymphadenopathy, occurrence of meningism and headache and with less common symptoms like alopecia, laryngitis, mild hepatitis, nephrotic syndrome, bone ache, and uveitis. Garnett et al. (1997), Singh et al. (1999) and LaFond et al. (2006) notified that this stage lasts up to an average of about 15 weeks. Singh et al. (1999) and LaFond et al. (2006) have reported that an untreated secondary syphilis develops asymptomatic state, also called latency which starts with two arbitrarily subdivided stages early (up to 2 years from primary infection) and late latency (approximately 2-46 years after primary infection or till tertiary stage progresses). LaFond et al. (2006) and French (2007) observed that about 30 to 40% of untreated cases develop the tertiary stage from latency. French (2007) and Marco De (2012) observed that during tertiary stage of syphilis infection individual may develop either cardiovascular syphilis (10%) or gummatous syphilis (15%) or neurosyphilis (6.5%) or meningovascular syphilis with the incubation period of 5 to12 years. Singh et al. (1999) noted that disease induced mortality occurs at tertiary stage only. Kent and Romanelli (2008) reported that people with tertiary syphilis are not infectious.

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