Issues with human pregnancy

Any pregnant mother who suspects she has been exposed to the bacteria must seek immediate advice from her obstetrician

Leptospirosis in animals and humans is a significant problem as it causes stillbirth, and in some regions is a major burden on the livestock industry. Leptospirosis in human mothers is an extremely dangerous condition for both the mother and her fetus – there is a risk in all trimesters of pregnancy and also a potential issue for breastfeeding mothers.

The first thing to say is that the fetus can be infected across the placenta, as the bacteria are small enough to pass the barrier. This ‘transplacental’ infection means that the fetus can become ill independent of the mother – who may have symptoms so mild she doesn’t notice any illness herself. The outcome for the fetus is difficult to predict, and severe illness in the mother is not always a bad prognosis for the fetus. Conversely, the fetus can be critically ill without the mother being aware of any symptoms.

Cases where only the mother becomes ill

In this case the level of fetal impact depends on the severity of the illness in the mother, and will lead to nonspecific effects such as developmental retardation. Where the placenta is affected the flow of oxygen to the fetus can be reduced, leading in some cases to death. In a hospital setting this can often be monitored and managed, however where the mother shows significant illness it can be impossible to maintain fetal safety and intervention may be required. It should be noted that with all due respect, pregnancy is a drain on the mother’s resources and her own recovery may be improved by clinical termination.

Cases where the fetus becomes infected

Transplacental infection is very common where the mother is infected, and the outcome varies depending on the timing. In the first and second trimester the fetal immunity response is absent, and the fetus will develop the same clinical symptoms as an adult – so can suffer jaundice, renal damage, vasculitis and haemorrhages. If the fetus is infected in the third trimester it can often present an immune response, and if it survives it will usually continue to develop and be born without abnormality. Where the infection takes hold early the fetus will usually die.

Breast feeding

It has been proven that the bacteria can pass to a baby via breast milk, and cause infection and illness despite the mother also producing antibodies in her milk. The duration of shedding is not known but is potentially several weeks, and mothers who become infected while breastfeeding should immediately stop and seek expert advice.

Pregnant mothers should not be permitted to work in high-risk occupations (such as veterinary work on suspect or confirmed animal cases, research and lab work with the bacteria, rice-farming or work involving exposure to feral rodents).