Currently, dengue is the most significant mosquito-borne disease in Sri Lanka. It is transmitted by the bite of an Aedes mosquito infected with any one of the four dengue viruses. Laboratory results have found that Dengue virus serotype 2 (DENV-2) to be the circulating strain in this outbreak . Due to heavy monsoon rains and improper waste disposal leading to stagnation of rainwater, is attributed to the increasing number of dengue cases.
The clinical assessment, diagnosis, treatment, and monitoring of dengue fever or dengue hemorrhagic fever during pregnancy can be very difficult due to various physiological changes occurring in pregnancy and other obstetric complications mimicking a clinical presentation of dengue infection. Fever with low PLT count, elevated liver enzymes, and right hypochondriac pain could be a part of HELLP syndrome or dengue illness. Labor pain can be misinterpreted as right upper quadrant pain. Therefore diagnosis of dengue can be misled by the presentation of other obstetric complications. Hence, clinicians should have a high index of suspicion for the diagnosis .
Having higher baseline heart rate and a fall in systolic and diastolic blood pressure induced by a reduction in systemic vascular resistance, may cause difficulty in early detection of entering the dengue critical phase, dengue shock syndrome and assessing response to fluid boluses as in this case.
Plasma volume expansion accompanied by a lesser increase in red cell volume causes a modest reduction in hematocrit . Therefore it is very important to determine the baseline PCV during the early part of dengue illness, as non-pregnant PCV values cannot be applied to pregnant patients. Without a baseline PCV, it is difficult to recognize the objective evidence of plasma leakage or concealed bleeding. In our patient, concealed bleeding was recognized by the sudden drop of PCV. However, a 20% rise of baseline PCV at the entrance into critical phase was not evident in this case, probably due to satisfactory hydration matching the rate of leaking. Over hydration in dengue can cause edema, pleural effusion, ascites and respiratory distress. Pregnancy itself can cause edema and mild respiratory discomfort due to gravid uterus. Clinical judgment alone may not be sufficient in such situations as in this case.
Pregnancy is associated with leukocytosis, primarily related to the increased circulation of neutrophils. In addition, the platelet count also begins to rise soon after delivery. Dengue infection causes leucopenia, thrombocytopenia, and a degree of thrombocytopenia is associated with the severity of dengue fever. Therefore, the interpretation of CBC and its correlation with the particular stage of dengue fever may not be accurate in pregnancy.
Still, there are no recommendations on mode and time of delivery for mothers with dengue infection. It was only due to this mother falling critically ill, was a multidisciplinary team approach considered. As fetal maturity was satisfactory but cervix not favorable, a CS was planned under spinal anaesthesia. It was carried out as urgent procedure due to several reasons. There was a high possibility of the patient entering the critical phase within the following few hours and if it did, the persistence of severe thrombocytopenia would last for next 2–3 days, with a high risk of bleeding during that period. Therefore immediate delivery was carried out.
Miscarriages, preterm labour, fetal abnormalities, increased risk of bleeding, low birth weight and maternal death in extreme cases, have been reported as adverse effects of dengue in pregnancy . There are reported cases of vertical transmission of dengue infection and they have been confirmed by identification of dengue virus in cord blood samples . Although dengue virus identification in cord blood was not performed in this case, development of fever on the 5th day of life and positive NS 1 antigen without a history of mosquito bites, supported the diagnosis of vertical transmission. The onset of fever following the 4–10 days of the normal incubation period of dengue is also favors the diagnosis . All reported cases of vertical transmission have occurred around the delivery, probably due to lack of sufficient time to confer the passive immunity to the fetus . Duration between the onset of maternal fever and delivery affects the time of onset of dengue fever in the neonate . Only a few case reports of vertical transmission of dengue are currently available and according to this limited literature, the time of onset of fever in neonates, ranged from 16 h to 11 days after birth and lasted from 2 to 6 days .
In conclusion, it seems that, dengue infection during pregnancy can have various adverse effects on the mother as well as on the neonate. A high index of suspicion, early diagnosis, close monitoring, timely intervention and critical consideration of physiological changes of pregnancy when interpreting clinical situation, would have led us to achieve the successful outcome of this case.