Table 1.

Summary of vector-borne infections in pregnancy.

Infectious disease		Organism	Vector	Complications in pregnancy	Vertical transmission	Prophylaxis/vaccination	Treatment in pregnancy
Mosquito borne
Malaria	protozoa	P. falciparum P. vivax P. ovale	Ae. aegypti	Low endemicity: risk of severe infection with maternal/foetal loss29 High endemicity: occult infections30	Accumulation in placenta but no vertical transmission	Doxycycline contraindicated ITNs RTS,S vaccine in development25	1T: Primaquine + clindamycin33 2–3T: ACT IPTp (sulfadoxine-pyrimethamine)33
Dengue	flavivirus	Dengue virus	Ae. aegypti Ae. albopictus	Increased risk of DHF and DHS54 Increased pre-eclampsia, obstetric haemorrhage, miscarriage, pre-term delivery55–57	1.6% transmission in cohort of 6564 One prospective study reports 18.5–22.7%65	CYD-DTV vaccine53	Supportive, monitor for need of C-section
Zika	flavivirus	Zika virus	Ae. aegypti	IUGR, oligohydramnios, stillbirth, miscarriage72	CZS (microcephaly, ventriculomegaly)11	2 vaccines in phase II trials (VRC 705, mRNA 1325)75	Supportive
Japanese encephalitis	flavivirus	Japanese encephalitis	Culux	Miscarriage, stillbirth. Outcomes similar in 3T infections compared with background population.79	Virus identified in brain and liver of stillborn79	Vaccine available IXIARO®, live attenuated vaccine80,81 not approved in pregnancy	Supportive
Chikungunya	togavirus	Chikungunya virus	Ae. Albopictus	Increased rate of admission84 Sepsis syndrome in mother17	Occurs in antepartum period, 50% of newborns develop severe complications12,17	Standard protective measures	Supportive
Tick borne
Lyme disease	spirochete bacterium	B. burgdorferi s.l. complex (incl afzelii, garinii, miyamoti)	I. scapilaris I. ricinus I. pacificus I. persulcatus	Stillbirth102 Possible congenital malformation including cardiac98	Spirochetemia of newborn,91–93 ECM rash96	Standard protective measures	Doxycycline contraindicated Amoxicillin 500 mg TID x14–21 days105 Ceftriaxone 2 g OD104–106
Human Granulocytic Anaplasmosis	gram negative bacterium	Anaplasma phagocytophilum	I. scapilaris I. pacificus	Mild symptomatic course in pregnancy.115 Miscarriage has been described113	Case reports of vertical transmission. No vertical transmission seen in treated mothers114,115	Standard protective measures	Doxycycline contraindicated (but has been used in some cases) Rifampicin 10 mg/kg bd × 5–7 days110,111 Penicillin if LD coinfection suspected
Human Monocytic Ehrlichiosis	gram negative bacterium	Ehrlichia chaffensis	Lone star tick Amblyomma (dog tick)	Minimal data. One case of a mother who developed appendicitis and had good outcome for mother and baby116	No data	Standard protective measures	Doxycycline used in one case with good outcome7 Rifampicin 10 mg/kg bd × 5–7 days110,111
Babesiosis	protozoa	Babesia microti Babesia divergens	I. scapilaris I. pacificus I. ricinus	Severe infection mimicking HELLP syndrome seen in pregnancy14	Rare, congenital syndrome of fever, thrombocytopenia, anaemia124	Standard protective measures	Clindamycin 600 mg PO TID + quinine 650 mg PO TID × 7–10 days (better placental penetration than standard atovaquone and azithromycin)14
Tick-borne encephalitis	flavivirus	Tick-borne encephalitis	I persulcatus I ricinus	Limited data, self-limiting illness, no evidence of adverse events in pregnancy	No evidence of vertical transmission in a single case of infection in pregnancy130	Standard protective measures	Inactivated vaccine available risk/benefit analysis for use in pregnancy131
Relapsing Fever	spirochete bacteria	B. miyamoti (seven other species) B. recurrentis	Ornithodoros (soft shell ticks) Ixodids lice	Decreased birth weight, pre-term delivery, miscarriage134,135	Transmission in utero and during pregnancy136,138	Standard protective measures	Doxycycline contraindicated Erythromycin139 - 7–10 days TBRF - single dose LBRF
Rickettsial diseases
Rocky Mountain Spotted Fever	proteobacterium	Rickettsia rickettseii	(Hardshell tick) Dermacentor variabilis Dermacentor andersoni	Adverse outcomes in pregnancy. Case series of 10 pregnancies, 3 maternal deaths, 3 miscarriages, 3 neonatal deaths144	No evidence of vertical transmission	Standard protective measures	Chloramphenicol 50–75 mg/kg in 4 divided doses for 5–7 days or until afebrile for 48–72 h. Doxycycline IV in severe cases143
ET	proteobacterium	Rickettsia prowazekii	(Human louse) Pediculosis humanus	No evidence for increased complication rate in pregnancy	No evidence of vertical transmission	Sanitation/hygiene
ST	proteobacterium	Orientalis tsutsugamushi	(Mite) Leptotrombidium	High levels of adverse outcomes in all trimesters including miscarriage, maternal death in some cases in studies of both ST and MT151,152	No evidence of vertical transmission	Standard protective measures	Doxycycline, azithromycin, rifampicin155
MT	proteobacterium	Rickettsia typhi	(Rat flea) Xenopsylla cheopis		No evidence of vertical transmission	Standard protective measures	Doxycycline153 (azithromycin inferior)
Fly borne diseases
Chagas disease	protozoa	Trypanosoma cruzii	(reduviid bug) Triatima infestans Rhodnius prolixans	Maternal infection does not appear to have negative outcomes during pregnancy or delivery161	Congenital CD in 5% of cases. Associated with prematurity, low birth weight, hepatosplenomegaly, anaemia, thrombocytopenia161	Standard protective measures	Treatment of mothers not advised during pregnancy163 Benznidazole and nifurtimox in newborn children min. 60 days of therapy164
Leishmaniasis	protozoa	Leishmania: infantum donovani aethiopica	(sandfly) New world: Lutzomyia Old world: Phlebotomus	Hepatosplenomegaly in pregnancy can be occult due to the increasing size of the uterus	A systematic review of 17 vertical transmissions showed 27% neonatal mortality169	Standard protective measures	Liposomal Amphotericin B safe but difficult to procure in resource limited settings. Miltefosine and pentavalent antimony are not advised in pregnancy due to teratogenicity and lack of data respectively
Bartonellosis (Carrion’s disease)	proteobacterium	Bartonella bacilliformis	(sandfly) Lutzomyia verrucarum	Carrion’s disease is associated with high maternal mortality, miscarriage, preterm birth and foetal death174	Vertical transmission is described in case reports175	Standard protective measures	Chloramphenicol is the mainstay of treatment, ciprofloxacin, rifampicin and streptomycin have also been used. No data exists on treatment of pregnant173

ET, epidemic typhus; HELLP, haemolytic anaemia, low platelets, elevated liver enzymes; IUGR, intrauterine growth restriction; LBRF, louse-borne relapsing fever; LD, Lyme disease; MT, murine typhus, ST, scrub typhus; TBRF, tick-borne relapsing fever.