Lecture 3 Epidemiology of Intestinal Infections

8/10/2019 Lecture 3 Epidemiology of Intestinal Infections

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EPIDEMI- OLOGY OF

INTES- TINAL

INFEC- TIONS


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EPIDEMIOLOGY OF INTESTINAL INFECTIONS Source of infection: at typhoid fever, shigellosis,paratyphoid A, some food poisonings ill person orbacteriocarrier; at paratyphoid B, salmonellosis,botulism - more often animals.

Bacteria carrying: acute, chronic, transient.Mechanism of transmission fecal-oral .Ways of transmission by the water, foods (atbotulism caned meat, mushrooms, as a rulehomemade), household things, dirty arms; flies.Epidemics contacts, water, food borne.Seasonality summer-autumn.


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The Division of Acute Intestinal Infections onsubtypes (by I.I. Yelkin)

anthroponosis the transmission from man to man

(shigellosis, cholera, typhoid fever, hepatitis ) zoonosis (salmonellosis, leptospirosis)Intensity of epidemic processsporadic morbidity epidemic

pandemic

Fecal-oral mechanism of transmission


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Peculiarity of epidemic process (character of infective episodes)

Food usage of dish without thermal handling, fly simultaneity and large-scale participation, shortincubation period, predominance the severe forms; rapiddescent of morbidity after removal of the transmissionfactor; absence of seasonal prevalenceHome gradual increasing the quantity of patients, slowmonotonous course, high morbidity of childrenW ater (acute and chronic) easiness of infection,duration of agent preservation, infection of open

reservoirs, water supply, wells (by sewage); character ofepisode is local (general water source), sharp increasingof morbidity in 1-2 weeks, involvement, basically, adults(drink not boiled water); removal of the cause lead toquick stopping of the disease;Seasonal prevalence mainly summer-autumn


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Domestic fly,its eggs,larvachrysalis .

The mechanicaltransmitters ofcausative agents often

are flies, if they haveaccess to sewage andfoodstuffs .


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Prophylaxis of acute intestinalinfections

Guaranteeing of the inhabitants with high qualitywater

Sani tary-hygienic contr ol the objects of socialnutri tion and food marketing , children'sestablishments; organization of collection and movingoff the sewage ; maintenance the rulesof personal hygiene

Detection of sick persons and bacter ia carr iersProphylactic medical examination of convalescentsSpecific prophylaxis (vaccines, serums, bacteriophage)


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The directions for hospitalization at

intestinal infectionsEpidemiological -Belongings the patient to the decreed group of

population,

Residence in the hostel, unsatisfactory sanitary-hygienic conditions

Clinical Severity of state,

Age (babies, advanced and old age persons),Presence of severe concomitant disease.


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yphoid fever

Typhoid fever is an acute disease from the groupof intestinal infections. Characterized by cycliccourse, bacteriemia, intoxication, rash on the skin,lesions of the lymphatic apparatus of the smallintestine.


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EPIDEMIOLOGY OF TYPHOID FEVER

Source of infection: ill person or bacteriocarrier;

Bacteria carrying: acute, chronic, transient.Infectiveness: last days of incubation period, all period of the disease Mechanism of transmission fecal-oral .

Ways of transmission by the water, foodstuffs, household things,

dirty arms; flies.Epidemics contacts, water, food borne.Susceptibility (index of contagiousness) 0,4Seasonality summer-autumn.Incubation period from 7 till 25 days.


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Salmonella typhi

Antigens

V i


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Source:

1. Patient2. Carrier of infectionMechanism of transmission fecal-oral

Susceptibility up to 40 50 %

31 2

Scheme of infections transmission:


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Water epidemic characterized by:

1. Sudden beginning

2. Most of the patients used common water-supply3. Mild forms of disease4. Fast decrease of epidemy after disinfection of

water


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Food epidemic characterized by:1. Acute or gradual beginning after consuming of

contaminated food (milk)2. Most patients fall ill after consuming milk from the

same source3. Most patients are infected after consuming of

unboiled milk (family outbreaks)Biggest part of sick contingent are childrenSevere forms of disease are common, becausemicroorganisms replicates in milk and create massiveinfectious dose


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CLINICAL SIGNS OF THE TYPHOIDFEVER

2-nd week:

Typhoid rash typhoid maculopapular rash (roseolaelevata), some elements, localized on the anter ior abdominal wall and

lateral wal ls (vest), new elements can appear , sometimes is pr esentlonger than fever.

H epato-splenomegalia. Status typhosus.

Serologic reactions.


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Laboratory confirmation of the diagnosis

Detection of the agent from the patient (from stool, urine, blood).

Detection of the specific antibodies and increasing their titer indynamic.

Method, that finally confirm the diagnosis of typhoid fever is bloodculture. At the fever period make the culture of blood from vein on

bile broth or Rappoports medium in correlation 1:10. On the 1-st week of the disease is needed 10 ml of blood, and each following week increasing its quantity on 5 ml (15, 20, 25). At the late periodof the disease (from 10-12 day), as for the diagnostic and for thecontrol by convalescence, make the bacteriological investigation offeces and urine. The duodenal contents take after the 10-th day ofnormal temperature.


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TREATMENT

Etiologic:Chloramphenicol, Ampicillin, Azithromycin ,Ciprofloxacin , O floxacin , Cefotaxim ,

Ceftriaxone V i antigen 400 cg 3 times subcutan. With

interval 7 daysPathogenic: diet 2, bed regime, disintoxication,

proteas inhibitors, probiotics, vitamins


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Antiepidemic measures:Examination on typhoid fever and paratyphoids allpatients with fever, which last more than 5 days (onceon hemoculture, and if fever continue more than 10days - Vidals reaction of hemaglutination or RIHA)

Examination of all persons, who are working at theindustries dealing with food, for detection ofbacteriocarriers

Obligatory hospitalization of patients and carriers intoinfectious hospital


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Convalescents are discharged from hospital onlyafter clinical recovery and three-time analysis of

feces and urine with 5-days interval, and bile in 10days after disappearing of clinical signs, if resultsare negative

three-month observation and 2-years registrationin sanitary-epidemic department with several timesbacterial examination

Current and final disinfection


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Cholera Bacteria


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Epidemiologic character of choleraInfective agents vib rio c ho lera (class ic, El-Tor)Source of the infection sic k, con valescen ts, vibrio carrier (1:100)

Mechanism of transmission fecal-oral Seasonal prevalence summer-autumn

Susceptibility - high

Epidemic and pandemic s pread ing

Types o f ep idemics water (more often); alimentary; home-contact(mixed)

Features of the 7 pandemic of cholera Endemic source Indonesia; possibility of implanting on the newt er r i to r ies w i th fo rming secondary endem ic sou rcesIsolation of V. holerae from water reservoirs before beginning theep idemicMore of ten and p rolon ged vibr ioc arr iage; predo m inance ofob l i tera ted and a typical form s; cons iderably low er lethal i ty


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Electronic microscopy ( negative contrast)Hepatitis virus A (d=27nm).


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Epidemiology of VHAViral hepatitis A - antroponosis. The source ofdisease is sick person in pre-jaundice period and in15 - 20 days of acute period of the disease. Primary localization of virus is gastrointestinaltract. Mechanism of transmission is fecal-oral.Virus is excreted from the organism of sick person

with feces.Specific final factors of transmission of hepatitis Avirus are water and food. Spreading depends onconditions of water supply and its relation withfecal contamination. Important factors oftransmission are flies, dirty arms.Susceptibility to the disease is high. Mainlychildren and adults up to 30 year fall sick.


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Shigellosis

the acute intestinal infection, thathas signs of intoxication andinflammation of the distal part of

bowel with diarrhea.


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Epidemiology of ShigellosisSh. dysenter iae;

Sh. f lexneri ;Sh. boydii;Sh. sonnei .

Source of infection patients, persons in period of convalescenceand bacteriocarries. The patients with acute shigellosis areespecially dangerous.

Mechanism fecal-oral Ways of transmission water (more oftenSh flexneri ),food staffs (

Sh sonnei ), dishes, dirty hands, flies

Seasonal - summer-autumnImmunity- type-specific


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Shigellas stained by Gram


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Etiologic diagnostic:

Detection of the agent from the feces, vomiting mass,lavage fluid

Serologic reactions (presence of antibodies to thecausative agent and increasing the titer indynamic)

Polymerase chain reaction (PCR) detection ofshigella DNA in feces and scraping of the rectummucous

Laboratory diagnostic of Shigellosis


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The shigella clumps on Endo medium.


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Coprogram at acute shigellosis. A lot of neutrophils and erythrocytes infeces. Staining by methylene blue.


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A B

Rectoscopic picture at shigellosis:A catarrhal proctosygmoiditis

B fibrinous-necrotic proctosygmoiditis and pseudomembranous colitis


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Complication ofshigellosis.

Rectal prolapsein baby.


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Staphylococcus toxicosis Incubation period, as rule, very

short (till 2 6 h). Clinically diseaseappears with headache, nausea, severevomiting, severe cutting like pain inupper half of abdomen, quicklydevelopment of dehydration symptoms.

Diarrhea may occur or not. Fever israrely high. In severe cases may appearcyanosis, seizures, collapse. However

within a day quick improvement occurs.


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Groups of Escherichia

1. Entero-invasive (28, 33, 112, 115). 2. Entero-pathogenic (18, 26, 44, 55). 3. Entero-toxogenic (6, 7, 8). 4. Entero-hemorrhagic (57).

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Lecture 3 Epidemiology of Intestinal Infections

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