Modes of infectious disease transmission
An infectious agent may be transmitted from its natural reservoir to a susceptible host in different ways.
There are different classifications for modes of transmission.
Here is one classification:
A. General transmission
B. Human-to-human transmission:
more in this file
Episodes of generalized pain in the lower limbs, referred to as ‘growing pains’ or nocturnal idiopathic pain, are common in preschool and school-aged children.
The pain often wakes the child from sleep and settles with massage or comforting.
The condition is poorly understood. Features to be fulfilled for this diagnosis are often referred to as the ‘Rules of Growing Pains’, which are:
- Age: range 3–12 years
- Pains symmetrical in lower limbs and not limited to joints.
- Pain often follows a day with exercise or other physical activities.
- pains never present at the start of the day after waking up
- physical activities not limited; no limp
- Physical examination normal (including pGALS), with the exception of joint hypermobility in some, and otherwise well.
OMPHALOMESENTERIC (VITELLINE) REMNANT
Partial or complete failure of involution of the omphalomesenteric duct can lead to a spectrum of anomalies in the newborn infant due to varying degrees and location of duct patency:
A. An umbilical cyst containing intestinal tissue.
B. Umbilical sinus with a band.
C. A persistent omphalomesenteric duct at the umbilicus with no intestinal connection results in an umbilical polyp.
D. Patent mid-duct with closure at both the umbilical and ileal ends of the omphalomesenteric duct results in an omphalomesenteric duct cyst. Because the two ends are fixed, this can lead to small bowel obstruction if loops of bowel twist around the cyst.
E. Persistent tissue at the ileum, with no connection to the umbilicus results in Meckel's diverticulum.
F. Complete patency results in the omphalomesenteric duct directly connecting the umbilicus to the terminal ileum. This can lead to intermittent drainage from the umbilicus " omphalomesenteric fistula". These infants will often appear to have a "stoma" in the umbilicus after cord separation.
G. Persistent fibrous cord (band) between the umbilicus and the ileum, which can lead to small bowel obstruction.
Def : Infection of the umbilicus and/or surrounding tissues.
Incidence : approximately 1 in 1,000 infants in developed countries where aseptic delivery and hygienic dry cord care are practiced.
Clinical features:
Mild discharge from the umbilical stump in the absence of inflammatory signs may be a normal occurrence, even when accompanied by some odor.
Unhealthy, discolored, and craggy-appearing umbilical stump; purulent drainage; periumbilical erythema; and induration.
Umbilical stump bleeding may occur with omphalitis because the infection delays thrombosis of the umbilical vessels.
Systemic signs, including lethargy, fever, irritability, temperature instability and poor feeding are suggestive of more severe infection or complication. The most common complication of omphalitis is sepsis.
Other complications include septic umbilical arteritis, portal vein thrombosis, liver abscess, peritonitis, intestinal gangrene, small bowel evisceration, necrotizing fasciitis, and death (Mortality rate is estimated between 7 and 15 percent)
Omphalitis is a polymicrobial infection. Historically, the predominant pathogens included Staphylococcus aureus, Streptococcus pyogenes, and Gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. However, with the routine use of antistaphylococcal cord care regimens, Gram-negative infections of the umbilicus have increased . In addition, anaerobic bacteria such as Bacteroides fragilis, Clostridium perfringens, and Clostridium tetani can contribute to umbilical infections, especially in infants born to mothers with chorioamnionitis . In these infants, foul smelling umbilical drainage is a typical finding.
Predictive (Presymptomatic) Genetic testing in pediatrics
Children may be referred because they are at increased risk of developing a genetic disorder in childhood or adult life (i.e the individual is clinically normal now).
n If the condition is likely to manifest in childhood (e.g. Duchenne muscular dystrophy) or if there are useful medical interventions available in childhood (e.g. screening by colonoscopy for colorectal tumours in children at risk of familial adenomatosis polyposis coli), then genetic testing is appropriate in childhood.
n If the child is at risk of a late-onset and untreatable disorder (e.g. Huntington disease), then deferring genetic testing until the child becomes an adult, or at least sufficiently mature to be actively involved in seeking the test and can make the decision for himself/herself, is usually preferred.
n If the child is not at risk of developing the condition but may be a carrier at risk of transmitting the disorder to their future children, then there is also a good case for deferring testing until the young person can participate actively in the decision. There may be less at stake with these reproductive carrier tests than with predictive tests for untreatable disorders, but there are still good grounds for caution and for careful discussion before proceeding with such tests.
These difficult issues are often best handled through a process of genetic counselling supporting open and sustained communication within the family and especially between parents and children.
Predictive testing is not usually offered without a formal process of genetic counselling over more than one consultation with time built in for reflection. Written consent for predictive testing is required by most laboratories.
So, Presymptomatic testing of disorders which manifest in adult life should not be performed until the individual can consent on their own behalf unless there is clear clinical benefit from testing earlier.
