L20 Infections (gestational, after)

Maternal Immune system has 2 main roles 1. Don’t kill the foetus • Foetus is ‘[blank_start]foreign[blank_end]’ therefore maternal immune system is [blank_start]modified[blank_end] so that the foreign tissue is not killed 2. Protect the foetus & newborn • Protect foetus from infections in utero ([blank_start]congenital[blank_end] infections) • Transfer maternal [blank_start]immunity[blank_end] to newborn

Maternal Immune system • Increase in [blank_start]number and activity[blank_end] of cells of the innate immune system, including NK cells • Cytokine production modified • [blank_start]Less[blank_end] antigen presentation at early stages • Increasing [blank_start]estradiol[blank_end] – augments Th2/[blank_start]Ig[blank_end] responses • Progesterone has a [blank_start]suppressive[blank_end] effect at later stages on acquired responses Result of this… • Increased [blank_start]susceptibility to diseases[blank_end] where cellular responses are important • Increased [blank_start]severity[blank_end] due to altered physiology in pregnancy eg cardiopulmonary changes

Transfer of maternal immunity Newborn has: • an [blank_start]underdeveloped[blank_end] immune system - immune system in the foetus is tolerogenic and [blank_start]non-reactive[blank_end], so doesn't try to kill mother. • is immunologically naïve - no [blank_start]memory[blank_end], every infection is new – will get sick • no/underdeveloped microflora • Newborn infants and children < 2 are highly [blank_start]susceptible[blank_end] to infection, particularly [blank_start]viral[blank_end] infections. • This can result in very serious disease - infections must be taken seriously and treated quickly. Maternal [blank_start]IgG[blank_end] can cross the placenta and accounts for the high levels present in the foetus. Baby born at 20 weeks ~ [blank_start]100 mg/dL[blank_end]. Breast milk contains [blank_start]IgA[blank_end] (& leukocytes) - transferred to neonate. Baby can produce only limited amounts of antibody, only [blank_start]IgM[blank_end] for first 6 months. At [blank_start]12[blank_end] months all maternal IgG is gone.

• GBS (group B streptococcus infection) is the most [blank_start]common[blank_end] infection of neonates, [blank_start]vertical[blank_end] transmission from mum during labor/delivery can occur • Infection in neonates – [blank_start]CNS, heart and lung[blank_end] pathology with 20-30% mortality in [blank_start]preterm[blank_end] infants, 2-3% in full-term • NZ has gone for a [blank_start]risk-based[blank_end] approach (rather then universal screening) • All newborns must be observed for [blank_start]1[blank_end] hour as per MoH guidelines • If risk factors for GBS extend to at least [blank_start]24[blank_end] hours

TORCH(Z) = Microbes associated with congenital infections. T - [blank_start]Toxoplasma gondii[blank_end] O - [blank_start]Other; inlcudes chicken pox and HIV[blank_end] R - [blank_start]Rubella[blank_end] C - [blank_start]Cytomegalovirus (CMV)[blank_end] H - [blank_start]HSV-1 and HSV-2[blank_end] Z - Zika?

Choose the incorrect statement about Cytomegalovirus (CMV).

CMV - Treatment • 6 months of [blank_start]oral Ganciclovir[blank_end] for newborns with [blank_start]severe[blank_end] symptomatic disease • No evidence base for treating [blank_start]older[blank_end] children • Requirement for new anti-virals with less [blank_start]toxicity[blank_end]

Rubella • Togaviridae, enveloped [blank_start]gram positive[blank_end] strand RNA virus, worldwide distribution • Transmission - respiratory via [blank_start]droplets[blank_end], fetal (infection rate [blank_start]decreases[blank_end] as pregnancy progresses) • Highly [blank_start]contagious[blank_end] • Originally thought to be a benign disease until birth defects were linked to disease early in pregnancy • Post-natal infection - Fever, aching, [blank_start]swollen[blank_end] lymph nodes, cough, [blank_start]sore[blank_end] throat. Self- [blank_start]limiting[blank_end]. • Congenital infection - infection in the first [blank_start]8[blank_end] weeks results in fetal damage in 85% of infants - immediate symptoms: cataracts, [blank_start]cardiac[blank_end] abnormalities, deafness - delayed symptoms - [blank_start]neurological[blank_end] impairment, [blank_start]behavioural[blank_end] disorders, diabetes • Treatment - treat [blank_start]symptoms[blank_end] • Prevention - Live vaccine ([blank_start]MMR[blank_end]), 90-97% effective

Varicella-Zoster Virus - enveloped ds DNA virus - highly [blank_start]contagious[blank_end], airborn [blank_start]transmission[blank_end] - 3 diseases - congenital varicella syndrome ([blank_start]neonates[blank_end]), chickenpox ([blank_start]children[blank_end]), shingles (herpes zoster - [blank_start]adults[blank_end]) - major complication is [blank_start]bacterial infections[blank_end] of rash - treatment - lotions to stop [blank_start]itching[blank_end], immunoglobulin or nucleotide analogues for at risk groups - congential disease in 1-2 trimester - very [blank_start]rare[blank_end], deformed [blank_start]limbs[blank_end], low birth [blank_start]weight[blank_end], scarring, [blank_start]mental[blank_end] defects. - 3 trimester - mother develops rash < [blank_start]4 days[blank_end] before delivery - disseminated & fulminant disease, [blank_start]30[blank_end]% mortality. - prevention: vaccine.

Post natal infections - mother: • Risk of any infection [blank_start]1–4[blank_end]% after vaginal delivery and [blank_start]10–20[blank_end]% after caesarean section • Mild [blank_start]breast[blank_end] infections most common, anti-microbials in 1/3 of cases • Infections associated with [blank_start]discontinuation[blank_end] of breast feeding

Mastitis • inflammation of the breast, may be due to [blank_start]infection[blank_end] • common – [blank_start]5-33[blank_end]% of lactating women, usually [blank_start]early[blank_end] in lactation, 3-11% will develop an [blank_start]abscess[blank_end] • usually [blank_start]unilateral[blank_end] • 70% cases [blank_start]infectious[blank_end] Signs & Symptoms • Local – breast [blank_start]pain[blank_end], engorgement, inflammation, heat, nipple [blank_start]damage[blank_end] (abscess – lump, necrosis) • Systemic - fever, malaise Treat: - Support mum & baby (hydrated, growing – continue breast feeding), analgesia, antimicrobials?