Parasitic Infections in Pregnancy

Abstract

Introduction In the developing world, pregnant women frequently experience a cycle of undernutrition and parasitic infections, resulting in adverse pregnancy outcomes including abortion, malformation, and neonatal death. Although malnutrition in general and parasitic infections specifically are less common in developed countries, no society is immune from their potential effects during pregnancy. Six parasitic infections that have major health, financial, or combined consequences worldwide are Lyme disease, tuberculosis (TB), malaria, syphilis, toxoplasmosis, and schistosomiasis. Lyme Disease In the early 1970s, a mysterious clustering of juvenile rheumatoid-arthritis-like cases occurring in children in and around Lyme, Connecticut, was subsequently recognized as a distinct disease and named Lyme disease. Further investigation revealed that tiny deer ticks infected with a spirochetal bacteria, later named Borrelia burgdorferi , were responsible for the outbreak. Subsequent research has discovered additional vectors, three distinct stages of the disease, and multiple therapy options. Ticks are divided into two families of medical importance: the Ixodidae (hard ticks) and Argasidae (soft ticks). Family Ixodidae contains ticks of the genus Ixodes, which are responsible for transmitting the spirochetal bacteria that cause Lyme disease. Black-legged ticks ( Ixodes scapularis ) transmit B. burgdorferi to humans in the northeastern and north central United States; on the Pacific coast, the bacteria are transmitted to humans by the western blacklegged tick ( I. pacificus ). In other parts of the world, including Europe, Lyme disease is transmitted by I. ricinus and other Ixodes species. The life cycle of ticks is 2 years and includes egg, larva, nymph, and adult. Ixodes scapularis nymphs appear to be the most important vector for transmission of B. burgdorferi . Ixodes ticks are much smaller than common dog and cattle ticks and usually feed and mate on deer during the adult part of their life cycle. The larvae (or seed ticks) are six-legged, whereas adults and nymphs are eight-legged. In their larval and nymphal stages, these ticks are no bigger than a pinhead. According to laboratory studies, a minimum of 36–48 hours of attachment of the tick is required for transmission,3 presumably because of the time required for the bacteria to travel from the midgut of the tick to its salivary glands.