Many would agree with me that one of the way to learn effectively, or in other words to read the examiners' MindSET is to go through the past year questions. Sure you will have lots of 'aha'experiences. The more 'aha' experiences you go through, the better will be your passing rate.
This question which I extracted from GP Learning modules of RACGP is similiar to one of the single best answer that came out in Part I, 2008. Watch out, it may come out again, in different forms though, or you may be asked about it in Part 2 on questions pertaining to your practice diary:
Concerning rotavirus, which one of the following statements is true?
a) A second rotavirus infection is more likely to cause severe gastroenteritis than the first infection
b) Rotavirus disease peaks in early winter all around Australia
c) Rotavirus is the main cause of severe, dehydrating gastroenteritis in infants and young children in developed and developing nations
d) It is estimated that 1 in 70 children were hospitalised by the age of 5 years due to rotavirus in Australia prior to the initiation of the national rotavirus vaccination program
Post your answer. If you are too shy, post it using pseudoname. Remember, we are here to learn, to stimulate each other so that all of us can walk through the exam with flying colours, hopefully. There is nothing to be shy of. Better do it here and get the encouragement from our colleagues than comitting the mistake during the exam. Hey, friends, 1 point short may pull you down from pass to fail. Mind you, many of us in the last exam just managed to scraped through or scrape under because of that one point.
The correct answer plus explanation shall be posted after 5 responses have been posted.
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7 comments:
My answer is C
yes the answer is C.seen this question before but can.t recall where.Doing past questions does help and it saves some time to tackle other question that we've not come across.Kudos to you for starting the ball rolling.
My answer is B
The infection is peak in early fall to winter in United States, but don't know whether it is true for Australia.
A is wrong because the severity of the infection decrease with repeated infection.
I think it is the main cause of severe dehydrating gastroenteritis in infants and young children in developig nations but not developed nations.
For D, I don't know.
I have reading material in digital form about rotavirus and viral gastroenteritis. How can I share it with others?
Thx for the responses. One more response from another participant and the answer together with the explanation shall be reveal. Get more candidates to participate and lets make it more interesting as we get along.
Dear Song wl,
You can copy and past it on to the comments and the rest will be able to read it.
Anyone can also post any questions which you think might come out. I shall copy and paste into the main post if I find time.
fracgp1
ROTAVIRUS
Etiologic Agent
Rotaviruses are members of the family Reoviridae. The viral genome consists of 11 segments of double-strand RNA that are enclosed in a triple-layered, nonenveloped, icosahedral capsid 75 nm in diameter. Viral protein 6 (VP6), the major structural protein, is the target of commercial immunoassays and determines the group specificity of rotaviruses. There are seven major groups of rotavirus (A through G); human illness is caused primarily by group A and, to a much lesser extent, by groups B and C. Two outer-capsid proteins, VP7 (G-protein) and VP4 (P-protein), determine serotype specificity, induce neutralizing antibodies, and form the basis for binary classification of rotaviruses (G and P types). The segmented genome of rotavirus allows genetic reassortment (i.e., exchange of genome segments between viruses) during co-infection—a property that may play a role in viral evolution and has been utilized in the development of reassortant animal-human rotavirus-based vaccines.
Epidemiology
Worldwide, nearly all children are infected with rotavirus by 3-5 years of age. Neonatal infections are common but are often asymptomatic or mild, presumably because of protection from maternal antibody or breast-feeding. First infections after 3 months of age are likely to be symptomatic, and the incidence of disease peaks among children 4-23 months of age. Reinfections are common, but the severity of disease decreases with each repeat infection. Therefore, severe rotavirus infections are relatively uncommon among older children and adults. Nevertheless, rotavirus can cause illness in parents and caretakers of children with rotavirus diarrhea, immunocompromised persons, travelers, and elderly individuals and should be considered in the differential diagnosis of gastroenteritis among adults. In temperate climates, rotavirus disease occurs predominantly during the cooler fall and winter months. In the United States, the rotavirus season each year begins in the Southwest during the autumn (October through December) and migrates across the continent, peaking in the Northeast during the spring (March through May) (Fig. 183-2); the reasons for this characteristic pattern are not clear. In tropical settings, rotavirus disease occurs year-round, with less pronounced seasonal peaks.
View Figure
FIGURE 183-2 Time of peak rotavirus activity in the contiguous 48 states: United States, July 1991 to June 1997. Data are from ~90 U.S. laboratories. (Adapted from TJ Torok et al: Visualizing geographic and temporal trends in rotavirus activity in the United States, 1991 to 1996. National Respiratory and Enteric Virus Surveillance System Collaborating Laboratories. Pediatr Infect Dis J 16:941, 1997.)
Rotavirus gastroenteritis is more frequently associated with dehydration than is gastroenteritis caused by other pathogens. Therefore, the proportion of gastroenteritis cases that are attributable to rotavirus increases with increasing severity of illness, ranging from a median of 8% in the community to 18% among outpatients and 40% among hospitalized patients. Each year, rotavirus is estimated to cause ~500,000 childhood deaths worldwide.
During episodes of rotavirus-associated diarrhea, virus is shed in large quantities in stool (107-1012/g). Viral shedding detectable by EIA usually subsides within 1 week but may persist for >30 days in immunocompromised individuals. Viral shedding may be detected for longer periods by sensitive molecular assays, such as PCR. The virus is transmitted predominantly through the fecal-oral route. Spread through respiratory secretions, person-to-person contact, or contaminated environmental surfaces has also been postulated to explain the rapid acquisition of antibody in the first 3 years of life, regardless of sanitary conditions.
At least 10 different G serotypes of group A rotavirus have been identified in humans, but only five types (G1 through G4 and G9) are common. While human rotavirus strains that possess a high degree of genetic homology with animal strains have been identified, animal-to-human transmission appears to be uncommon.
Group B rotaviruses have been associated with several large epidemics of severe gastroenteritis among adults in China since 1982 and have recently been identified in India but not in other parts of the world. Group C rotaviruses have been associated with a small proportion of pediatric gastroenteritis cases in several countries worldwide.
Pathogenesis
Rotaviruses infect and ultimately destroy mature enterocytes in the villous epithelium of the proximal small intestine. The loss of absorptive villous epithelium, coupled with the proliferation of secretory crypt cells, results in secretory diarrhea. Brush-border enzymes characteristic of differentiated cells are reduced, and this change leads to the accumulation of unmetabolized disaccharides and consequent osmotic diarrhea. Studies in mice indicate that a nonstructural rotavirus protein, NSP4, functions as an enterotoxin and contributes to secretory diarrhea by altering epithelial cell function and permeability. In addition, rotavirus may evoke fluid secretion through activation of the enteric nervous system in the intestinal wall. Recent data indicate that rotavirus antigenemia and viremia are common among children with acute rotavirus infection, although the antigen and RNA levels in serum are substantially lower than those in stool.
Clinical Manifestations
The clinical spectrum of rotavirus infection ranges from subclinical infection to severe gastroenteritis leading to life-threatening dehydration. After an incubation period of 1-3 days, the illness has an abrupt onset, with vomiting frequently preceding the onset of diarrhea. Up to one-third of patients may have a temperature of >39°C. The stools are characteristically loose and watery and only infrequently contain red or white cells. Gastrointestinal symptoms generally resolve in 3-7 days.
Respiratory and neurologic features in children with rotavirus infection have been reported, but causal associations have not been proven. Moreover, rotavirus infection has been associated with a variety of other clinical conditions (e.g., sudden infant death syndrome, necrotizing enterocolitis, intussusception, Kawasaki disease, and type 1 diabetes), but no causal relationship has been confirmed with any of these syndromes.
Rotavirus does not appear to be a major opportunistic pathogen in children with HIV infection. In severely immunodeficient children, rotavirus can cause protracted diarrhea with prolonged viral excretion and, in rare instances, can disseminate systemically. Persons who are immunosuppressed for bone marrow transplantation are also at risk for severe or even fatal rotavirus disease.
Immunity
Protection against rotavirus disease is correlated with the presence of virus-specific secretory IgA antibodies in the intestine and, to some extent, the serum. Because virus-specific IgA production at the intestinal surface is short-lived, complete protection against disease is only temporary. However, each infection and subsequent reinfection confers progressively greater immunity; thus severe disease is most common among young children with first or second infections. Immunologic memory is believed to be important in the attenuation of disease severity upon reinfection.
Diagnosis
Illness caused by rotavirus is difficult to distinguish clinically from that caused by other enteric viruses. Because large quantities of virus are shed in feces, the diagnosis can usually be confirmed by a wide variety of commercially available EIAs or by techniques for detecting viral RNA, such as gel electrophoresis, probe hybridization, or PCR.
ROTAVIRUS INFECTIONS
Rotavirus gastroenteritis can lead to severe dehydration. Thus appropriate treatment should be instituted early. Standard oral rehydration therapy is successful in most children who can take oral fluids, but IV fluid replacement may be required for patients who are severely dehydrated or are unable to tolerate oral therapy because of frequent vomiting. The therapeutic role of probiotics, bismuth subsalicylate, enkephalinase inhibitors, and nitazoxanide has been evaluated in clinical studies but is not clearly defined. Antibiotics and antimotility agents should be avoided. In immunocompromised children with chronic symptomatic rotavirus disease, orally administered immunoglobulins or colostrum may resolve symptoms, but the choice of agents and their doses have not been well studied and are often empirical.
Prevention
Efforts to develop rotavirus vaccines were pursued because it was apparent—given the similar rates in less developed and industrialized nations—that improvements in hygiene and sanitation were unlikely to reduce disease incidence. The first rotavirus vaccine licensed in the United States in 1998 was withdrawn from the market within 1 year because it was linked with intussusception, a severe bowel obstruction.
In 2006, promising safety and efficacy results for two new rotavirus vaccines were reported from large clinical trials conducted in North America, Europe, and Latin America. One of these vaccines, a multivalent bovine-human reassortant rotavirus-based preparation, was recommended for routine immunization of all U.S. infants in early 2006. The second vaccine, based on a single attenuated human rotavirus strain, is not licensed in the United States but has been introduced in immunization programs in several countries in Latin America and Europe.
Global Considerations
Rotavirus is ubiquitous and infects nearly all children worldwide by 5 years of age. However, compared with rotavirus disease in industrialized countries, that in developing countries occurs at a younger age, is less seasonal, is more often associated with severe outcomes (including death), and is more frequently caused by uncommon rotavirus strains. The different epidemiology of rotavirus disease and the greater prevalence of co-infection with other enteric pathogens, of comorbidities, and of malnutrition in developing countries may adversely affect the performance of rotavirus vaccines. Therefore, before global recommendations for vaccine use can be issued, it is vital to evaluate the efficacy of rotavirus vaccines in resourcepoor settings of Africa and Asia. Trials in these areas are under way.
Well, our blog is new so 5 responses may not happen until we get more participants in. In order not to frustrate those wanting for the answer, I decided to post the answer and explanation prematurely for this question:
The correct response is C. Congrats to those who have strike it.
Rotavirus is indeed the main cause of severe, dehydrating gastroenteritis in infants and young children in both developed and developing nations. Rotavirus infections are more likely to result in hospitalisation than other common causes of diarrhoea and it is estimated that in Australia, prior to the national rotavirus vaccination program, 1 in 27 children were hospitalised by the age of 5 years due to rotavirus. The first rotavirus infection is most commonly associated with severe diarrhoea and dehydration. Prior to the national vaccination program, the first rotavirus infection generally occurred between the ages of 3 and 36 months.
The incidence of rotavirus infection generally displays a seasonal pattern in temperate Australia, peaking in mid-late winter; however, seasonal rotavirus patterns don't exist in tropical and arid regions of the country.
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