1. Cholera

2. Cholera is an extremely virulent disease. It affects both children and adults. It characterized in its severe form by sudden onset, profuse painless watery stools (rice- water stool), nausea and profuse vomiting early in the disease. In untreated cases, rapid dehydration, acidosis, circulatory collapse, renal failure and rapid death. In most cases → asymptomatic or mild diarrhea [El Tor biotype]. Proper rehydration → CFR < 1%. Pathogenesis: Not invasive mo → enterotoxin liberation → stimulate adenyl-cyclase in gut → massive fluid out put + poor absorption.

3. Diagnosis Clinical Stool examination. Serological test. Infectiuos agents: V. cholerae O1 and O139 Vibrio cholerae O1 → 2 biotypes: classical & El Tor Each biotype → 3 serotypes: Inaba, Ogawa, & Hikojima (rare)

4. Infectious agents Cholera due to El Tor differs from classical cholera in following aspects: Large number of mild & asymptomatic cases: 1 sympt / 100 asympt. Hardier &remain viable for longer period in water. Longer period of shedding by patient & carriers (possibility of chronic carriers).

5. Occurence Cholera is one of the oldest epidemic diseases. Epidemics and pandemics are strongly linked to the consumption of unsafe water, poor hygiene and crowded living conditions. There are roughly 1.4 to 4.3 million cases, and 28 000 to 142 000 deaths/year worldwide due to cholera. The short incubation period of 2 hours to 5 days, is 1 factor that triggers the potentially explosive pattern of outbreaks.

6. Reservoir: Humans (Sick person, Convalescent patient or Carriers). Mode of transmission Mode of transmission Ingestion of an infective dose of contaminated food or water and can transmitted through many mechanisms. Drinking water contaminated: at source, during transportation or during storage at home. Beverages, ice …etc.

7. Incubation period: few hours – 5 days, usually 2 – 3 days. Period of communicability: As long as stools are positive, usually only a few days after recovery. Occasionally the carrier state may persist for several months. Tetracycline shorten the period of communicability.

8. Susceptability Susceptibility is variable Immunity: O1 classical biotype infection → protection against classical or El Tor biotype long lasting or permanent; in contrast an initial clinical infection with El Tor → modest immunity limited to El Tor. Infection with O1 affords no protection against O139 infection and vice-versa. Typical settings → periurban slums Nutritional status → poor nutrition

9. Susceptability Gastric acidity (host factor) → protective ◦ Normal person + 10 11 M.O → infection ◦ Normal person + antacid + 10 6 M.O → infection Other clinical conditions (host factors): cholecystitis, hook worms (Ascaris ?) and blood group O. Breast feeding → protective

10. Control Preventive measures A- Preventive measures : The long-term solution for cholera control lies in economic development and universal access to safe drinking water and adequate sanitation, which is key in preventing both epidemic and endemic cholera. Vaccine. Measures that inhibit the movement of people, foods or other goods are not providing effective to control cholera.

11. Vaccination Two oral cholera vaccines (OCV): Safe and provide significant protection (>50%) for 2 years. Used by travelers to endemic areas. Live vaccine, single-dose, against O1 & O139 and adopted by WHO as public health tool in cholera outbreak. Killed vaccine, 2-dose regime. The use of the parenteral cholera vaccine has never been recommended by WHO due to its low protective efficacy and the high occurrence of severe adverse reactions.

12. B- Control of patients, contacts and environment: Reporting: Obligatory (internationally), Class I reporting. Isolation:  Severely ill patients → Hospitalization.  Less severe cases → out patient (oral rehydration + antimicrobial).  Cholera wards can be operated. Disinfection of feces, vomit, linens and articles used by the patients by heat or carbonic acid. Quarantine: not applicable.

13. Management of contacts: Management of contacts: Surveillance of persons who shared food and drink with a cholera patient for 5 days from last exposure. Household contacts → chemoprophylaxis: Adults Adults → tetracycline 500mg x 4/ day for 3 days. Or doxycycline 300 mg single dose. Children Children  > 9 years → tetracycline 50mg/Kg/day for 3 days. Children  < 9 years → erythromycin 40mg/Kg/day for 3 days.

14. Mass chemoprophylaxis of whole communities is never indicated (waste of resources and can lead to antibiotics resistance). Immunization of contacts is not indicated. Investigation of contacts and source of infection: - Investigate: polluted drinking water and contaminated food. - Stool culture is recommended only for household contacts.

15. Specifice treatment Objectives: Rapid fluid replacement [the cornerstone of cholera treatment is timely and adequate rehydration]. Antibiotic (tetracycline) — secondary to rehydration: Shorten duration of diarrhea. Reduce the volume of rehydration fluids required. Shorten the duration of vibrio excretion. - Mild to moderate dehydration → ORS - Severe dehydration → rapid I.V. fluid

16. Antimicrobials: - Adults → tetracycline 500 mg x 4/ day for 3 day or doxycycline 300 mg single dose. -Children → tetracycline 12.5 mg/Kg/day for 3 days. -If resistant to tetracycline → erythromycin 250 mg x 4 for adults and 30mg/Kg/day for children, for 3 days. Or ciprofloxacin 250 mg once daily for 3 days.

17. Enteric fever

18. A systemic bacterial disease with insidious onset of sustained fever, marked headache, anorexia, relative bradycardia, splenomegaly, and rose spots on trunks in 25% of white-skinned patients in 2 nd week. Inapparent or mild illnesses occur, especially in endemic areas and constitute about 60-90% of typhoid patients. Severe cases with complications can occur (bleeding or perforation) in 1% of cases.

19. In severe cases, the CFR → 10% - 20% befor antibiotic era, which drop below 1% with prompt antibiotic. 15%-20% of patients may experience relapses (generally milder than the initial clinical illness). Paratyphoid fever A and B presents a similar clinical picture, but tends to be milder, and the CFR is much lower. Relapses occurs in approximately 3 – 4 %

20. Infectious agents: Typhoid fever → S. Typhi Paratyphoid fever → S. Paratyphi A & B.

21. Diagnosis 1. Clinical diagnosis: unexplained prolonged fever. 2. Isolation of microorganism by culture 3. Serology : Widal test. Old serological assay for detecting IgM and IgG antibodies against O and H antigens of salmonella. The test is unreliable but widely used in developing countries because of its low cost. IDL Tubex ® test:, one step test, rapid result (2 minutes). It detect IgM 90% Sensitivity and specificity better than Widal test. Typhidot ® test: sensitivity 75%, specificity 95%, detect specific IgM & IgG. Newer Typhidot-M ® test: detect specific IgM. IgM dipstick test.

22. Occurrence: Worldwide occur in all area where water supplies and sanitation are substandard. The annual Incidence of typhoid fever is about 17 million cases with approximately 600 000 deaths. Almost 80% of cases and deaths are in Asia and most of others occur in Africa and Latin America.

23. Reservoir Reservoir: Humans : All ages - both sexes,cases & carriers Cases:mild,missed or severe Carriers:temporary (convalescent) or chronic carrier Convalescent carriers → excrete the bacilli for 6 -8 weeks, after 3 months only 4% remain excreting M.O. After 1 year only 3% → chronic carrier (either fecal or urinary carrier). In most chronic carriers, the microorganism persist in the gallbladder and in the biliary tract. M.O excreted either continously or intermittently

24. Mode of transmission: Feco-oral route by ingestion of water and food contaminated by feces and urine of patients and carriers. - Raw fruits and vegetables especially when human excreta used as fertilizer. -Sea food. -Contaminated milks and milk products, -Flies may infect foods in which the organism then multiplies to infective doses.

25. Incubation period: 8 - 14 days but it may be as short as 3 days up to 60 days. Period of communicability: Period of communicability: as long as the bacilli appear in the excreta. Usually from 1 st week throughout the convalescence. (10% of untreated cases excrete bacilli for 3 months after onset of symptoms).

26. Susceptibility: Susceptibility is general, and increase in person with gastric achlorhydria, and possibly in those with HIV (+ve). Serum antibodies (O &H) are not the primary defenses against infection; S. typhi being an intracellular organism, cell- mediated immunity play an major role in combating the infection. The immunity is temporal, 2 nd attacks infection may occur.

27. A- Preventive measures: A- Preventive measures: 1.Educate the public … 2.Personal hygiene particularly food handlers. 3.Sanitary sewage disposal. 4.Provide, clean and chlorinate public and private water supplies. 5.Control flies. 6.Use of sanitary practices for food preparation, handling and storage especially of salads 7.Pasteurization or boiling of milk and diary products.

28. 8) Exclusion of typhoid carriers from handling foods until 3 consecutive negative stool cultures at least 1 month apart and at least 48 hours after antimicrobial therapy has stopped. Rx of chronic carriers → ciprofloxacine or norfloxacine twice daily for 28 days → 80% successful. Surgery → cholecystectomy + Ampicillin therapy The management of carriers continues to be an unsolved problem. This is the crux of the problem, in the elimination of typhoid fever.

29. 9. Immunization Vaccination of high-risk populations is considered the most promising strategy for the control of typhoid fever. Immunization is not routinely recommended in non- endemic areas. 1- TAB vaccine: Killed injectable vaccine, given 2 doses at one month interval. Side effect: redness, fever, nausea and headache. Booster every 3 years. Age: adults and children ≥ 2 years. 2- Injectable Vi vaccine: licensed in 1994, Age: adults and children ≥ 2 years.

30. 3- Oral vaccine Ty 21a (typhoral or Vivotif): 3- Oral vaccine Ty 21a (typhoral or Vivotif): oral, live attenuated, 3 doses: day 1, 3 and 5. Protection commences 2 weeks after taking the last capsule and last for at least 3 years. Therefore, a booster dose is needed every 3 years. - Age: adults and children > 6 years. - Three years protection around 90%. - Now > 60 countries adopted.

31. Immunization Indications 1. Food handlers 2. Workers in water, sewage plants Obligatory 3. Swimming pools attendances in Iraq 4. Visitors to endemic areas 5. School-age children living WHO in endemic areas.

32. B- Control of patients, contacts &environment: 1) Reporting 2) Isolation: Enteric precaution while ill (hospital care in acute illness). Release from supervision until 3 consecutive negative cultures of stool (and urine in patients with schistosomiasis) on 3 separate days and at least 48 hours after antimicrobial therapy has stopped and not earlier than 1 month after onset. If any of these is positive, repeat cultures at monthly interval during 12 months. 3) Disinfection of feces and urine. 4) Quarantine: not applicable.

33. B- Control of patients, contacts and environment: 5) Immunization of contacts: is of limited value. 6) Investigation of contacts and source of infection: 7) Specific treatment: is by ciprofloxacin for 2 weeks or ceftriaxone or azithromycine. - Chloramphenicol, amoxicillin, ampicillin and trimetheprine-sulfamethoxazole are equally effective.

34. THANKS