As Layla picked the green beans and weeded around the squash one July morning, she pondered how their lifestyle would change in November when their ﬁrst child was due to be born. She was pleased to be able to raise their child in the unpolluted environment of their country farm and nourish him with homegrown foods free of the pesticides and preservatives found in many commercially produced items. “Of course,” Layla said to herself while patting her belly, “I think we’ll have to break down and drive a little more this winter. You’ll be a bit too small for my baby bicycle seat.” As if on cue, the baby started “dancing.” Laughing, Layla collected the baskets of produce she had harvested and headed to the kitchen to start making lunch. After rinsing the fresh-picked fruits and vegetables, Layla used her garden’s bounty to assemble a delicious salad and homemade strawberry shortcake with cream from Josie, their cow. Later that afternoon, the couple went to Dr. Schneider’s ofﬁce for Layla’s monthly prenatal examination. They watched with amazement as the obstetricianused ultrasoundto measure the baby’s growth, conﬁrming that Layla was 23 weeks pregnant. Dr. Schneider pointed out different features of their developing child. They saw a tiny beating heart and learned it was time to paint the nursery blue!
Layla’s pregnancy progressed normally until her next appointment at 27 weeks gestation. Dr. Schneider was surprised to ﬁnd Layla hadn’t gained any weight in four weeks. “At this stage of your pregnancy, you should be gaining about 0.5 to 1 pound per week,” Dr. Schneider said with concern. “Are you eating enough nutritious foods?” Layla was happy to report a healthy appetite that she regularly indulged with the foods she and Steve raised. “I bet it’s the extra exercise I’m getting,” Layla explained. “I’ve been canning produce as fast as I can harvest the garden and orchard. I’m up and down the hillside a dozen times a day hauling a full bushel basket, so I bet I’m just burning off the calories with my gardening.” Dr. Schneider cautioned Layla not to be lifting heavy baskets and encouraged her to add an afternoon snack to her usual diet. “I want to see you in two weeks to be sure your weight gain is back on track,” Dr. Schneider ordered. Exactly one week later, Layla called and scheduled an urgent appointment. For the previous 48 hours, Layla had experienced signiﬁcant vomiting and diarrhea. By the time she arrived at Dr. Schneider’s, Layla was weak and slightly dehydrated. Frantic, Layla reported a decrease in fetal activity. Dr. Schneider admitted Layla to the hospital for IV ﬂuids and prescribed medication to ease her GI distress.
- What infections manifest with these symptoms? Are any speciﬁcally associated with pregnancy?
An hour later Dr. Schneider performed an ultrasound to check on the progress of Layla’s developing son and was shocked to see no fetal growth since her week 23 examination. In the morning, Dr. Schneider arrived at the hospital early to examine Layla and her baby. Steve was asleep in a chair and Layla sat up in bed weeping gently. She hadn’t felt the baby move since midnight. Dr. Schneider conﬁrmed Layla’s worst fears with another ultrasound, which showed no fetal heartbeat. Labor was induced to deliver Layla and Steve’s 28-week-old stillborn son. A fetal autopsy revealed elevated titers of toxoplasmosis antibodies, hydrocephalusand brain lesions.
- Describe the causative agent of toxoplasmosis. Outline the life cycle of this microorganism.
A week later, Layla and Steve met with Dr. Schneider to review the autopsy report and answer their long list of questions. “So, I got toxoplasmosis and that’s why I was so sick…and then I made the baby sick too,” Layla said dismally.
- Were Layla’s symptoms consistent with toxoplasmosis? Describe the usual signs and symptoms of this infection. What is a secondary infection?
“No,” Dr. Schneider replied, “not exactly. Your GI symptoms were coincidental and represent a secondary infection. They simply alerted us to the problem with the baby’s growth. It does; however, appear you’ve been infected with toxoplasmosis and the pathogen crossed the placenta to affect your baby. “Wait a minute,” Steve interjected. “How did Layla get toxoplasmosis? I’ve heard about this disease. Pregnant women get it from changing litter boxes. We don’t have a pet cat. In fact, we don’t even have strays in our barn!”
- Are litter boxes a source of pathogen transmission? Explain.
- What are the most common means of toxoplasmosis transmission? Based on this information, was Layla at high risk for infection? How can toxoplasmosis be prevented?
- What is the prevalence of toxoplasmosis?
“Dr. Schneider, was there any way to diagnose and treat my infection that might have saved our baby?” Layla asked. “There are different diagnostic tests for toxoplasmosis, but they aren’t routinely run in a prenatal panel in the U.S. unless we have reason to suspect infection,” Dr. Schneider explained. “If a pregnant woman is infected, several treatment protocols are available, but the beneﬁts must be carefully weighed against the risks since the likelihood of transmission and fetal damage varies with the gestational age of the mother seroconversion
- How is toxoplasmosis typically diagnosed? What challenges are associated with interpreting test results? How can fetal infection be determined?
- Describe the principal treatment protocols for toxoplasmosis infection in a pregnant patient. Indicate the pros and cons of each treatment. When is the best time during the course of Toxoplasma gondii infection to administer treatment to a patient?
- Explain the correlation between the gestational age of maternal seroconversion for toxoplasmosis and the risk of fetal infection.
- What signs and symptoms are expressed by neonates with congenital toxoplasmosis? What symptoms are expressed by infected children within the ﬁrst year of life? What is the miscarriage rate associated with fetal toxoplasmosis?
“Now that I’ve been infected with toxoplasmosis, do I need to be treated? If I’m cured can we still have other children, or will I infect them too, causing another miscarriage?” Layla asked hopefully. “Not to worry,” Dr. Schneider consoled the young couple. “You’ve suffered a devastating loss, but I’m conﬁdent you’ll soon be parents.”
- Is it necessary to treat Layla for toxoplasmosis? Can she have subsequent children without risking their infection?
Anderson, R. et.al. Case study in microbiology: A Personal Approach, Publisher: John Wiley & Sons Copyright year: © 2006.
Case Study # 4
Sex, Drugs and Rock and Roll
Jim was a police ofﬁcer and his wife Barb a nurse at the hospital that handled most of the city’s poor. It was inevitable that their paths would occasionally cross during work. Tonight, they were both at a community outreach meeting concerning the problems caused by the increase in crystal meth use. Methamphetamine, or crystal meth, is a powerfully addictive stimulant that has an intense euphoric
effect. Jim saw its effect when chronic crystal meth users would embark on binges of constant meth use. The results were universally disastrous––intense paranoia, visual and auditory hallucinations, and violently out-of-control behavior. Barb saw another side of abuse of the drug. Crystal meth use has a potent effect of increasing the sex drive. As a result, crystal meth users were more likely than others
to engage in high-risk sexual behaviors and have more sexual partners than nonusers. Barb had seen a signiﬁcant increase in cases of gonorrhea in general, and increases in syphilis and HIV disease among gay men. Long-term users of crystal meth build up a tolerance to the drug. As a result, many choose to inject the drug to continue to get high. Not unsurprisingly, intravenous drug use increases the spread of HIV as users share needles (and therefore exchange small amounts of blood). At counseling programs designed to help HIV-positive gay and bisexual men who use crystal meth, about half had injected meth during the last year. Neither Jim nor Barb was the type to sit back and hope for the best. They had much invested in their community where their children went to school. Both were consistent volunteers. Jim already coached soccer and led scouts. Barb was active at their church and volunteered to help students with reading and math at school. At the end of the meeting, both took part in the discussion and planning sessions on how to help the community stem the problems caused by widespread crystal
- What types of behaviors are considered high risk for acquiring sexually transmitted infections?
- What pathogens are responsible for causing these STI’s? Describe each.
- What are the clinical signs and symptoms of gonorrhea? Compare them to those caused by syphilis.
- What other STIs would you expect to be increased following an increase in high-risk sexual behaviors and an increase in sexual partners?
- In general, how can the spread of STIs be reduced?
- Are the activities needed to prevent or reduce the spread of STIs likely to be followed by crystal meth users?
- What recommendations would you make to Jim and Barb’s community group to help reduce the spread of STIs among the crystal meth users?