tropical disease

1. SARS
Hafiz M. Irfan RN, BSN, MSPH

2. SARS
• A respiratory disease in humans
• The severe acute respiratory
syndrome is caused by an infection
with the SARS virus.
• It is a relatively new disease, being
first described in the Guangdong
Province of China in November 2002

3. Pathogen
• Caused by the coronavirus
(SARS-CoV).
• large, enveloped, single-
stranded RNA viruses that
replicate in the cytoplasm of
animal host cells
• Characteristic appearance of
surface projections, giving
rise to the virus' name
(corona, Latin = crown).

4. Incubation Period:
• 2-10 days
Transmission
• Close face-to-face contact
• Droplet spread when a patient sneezes
or cough
• Feco-oral & airborne transmission seem
to be less frequent.
Reservior
• Civet (animal like a cat)
• Virus can survive in dry surface for 3-4
hrs

5. Civet

7. S/S
• Fever above 38 °C (100.4 °F).
• Myalgia
• Lethargy
• Gastrointestinal symptoms
• Cough
• Sore throat
• Rhinitis
• Shortness of breath
• Headache
• Symptoms usually appear 3–7 days following
• About 10–20% of cases require mechanical ventilation

8. Complications
• Pneumonia
• Respiratory failure
• Death

9. Diagnosis
• Clinical examination is misleading
• CXR
• CT-scans
• Anti body detection When infected by SARS-
CoV antibodies change in levels
• ELISA (Enzyme-linked immunosorbent assay)
• Mild Thrombocytopenia and Leukopenia
• LDH (Lactate dehydrogenase test)

10. Treatment
• All patients of SARS infection should be
admitted to hospital
• Isolated to prevent further spread of disease.
• Fever management
• Antibiotics against pneumonia
• Anti-viral agents (Ribavirin)
• Steroids
• Protease inhibitor:Lopinavir-ritonavir
• Supportive therapy such as oxygen and
asthmatic medication is also commonly used
• Identification of SARS contacts

11. Prevention
Break the chain of transmission by;
• Effective contact tracing
• Isolation
• Quarantine of exposed persons
• Avoid contact with respiratory secretions
• Disposal of contaminated articles
• Monitoring of close contacts
• Avoid traveling to risk areas
• Limit the number of visitors to patient
• Screening of travelers
• Use of mask, gloves, gowns and hand washing.
• Respiratory isolation precautions
• Disinfection
• No vaccine available

12. Anthrax(3)

13. ANTHRAX
• The anthrax bacillus, Bacillus anthracis, was the first
bacterium shown to be the cause of a disease- Koch’s
Postulate
• In 1877, Robert Koch grew the organism in pure culture,
demonstrated its ability to form endospores, and
produced experimental anthrax by injecting it into
animals.
• Anthrax is a disease of domesticated and wild animals
• Men suffer from anthrax occasionally due to close
contact with infected animal or animal products
BImal K Das, Microbiology,

14. Bacillus anthracis
• Gram positive rods
• Capsulated ( Protein) – Capsule form in animal
tissue and in special
laboratory condition ( 5% CO2)
• Forms endospore, centrally located, do not form in
animal tissues
• MacFadyean ( Polychrome methylene blue) stain
blue bacilli with purple capsule
• Aerobic/ Facultative anerobe

15. Robert Koch's original micrographs of the anthrax bacillus

16. Bacillus anthracis. Gram stain. The cells have characteristic
squared ends. The endospores are ellipsoidal shaped and located
centrally in the sporangium. The spores are highly refractile to
light and resistant to staining.

17. McFadyean's reaction showing short chains of Bacillus
anthracis cells lying among amorphous, disintegrated
capsular material. White blood cells can also be seen.

18. Epiedemiology
• Distribution worldwide
• Not common in West. Common in Africa ( Zimbabwe),
S.E. Asia, China, South America, Turkey, Pakistan, India
• Human to human or animal to animal transmission is rare
•Grazing animals become infected through ingestion of
spores in the soil ( Carcasses become the source)
Epidemic : A. Spread to contiguous geographic areas by
infected animal
B. Non contiguous geographic areas by
- biting flies ( Zimbabwe)
- Vultures
- Contaminated surface water pool

19. Pathogenesis
Endospores
(Abrasion, inhalation, ingestion)
Death Introduced
Septicemia Phagocytosed by Macrophages
10 7 to 10 8/ml Regional LNs
Blood stream
Multiply in Lymphatics Germinate inside Macrophages
Release
Vegetative Forms
BImal K Das, Microbiology, AI

20. Clinically three forms of Human anthrax occur
A. Cutaneous anthrax
B. Pulmonary anthrax
C. Intestinal anthrax
Broadly can be classified into
Non Industrial/Agricultural ( Through infected animals):
Cutaneous anthrax
Rarely intestinal anthrax
Industrial Anthrax ( Through animal products):
Mostly through animal products( wools, hair, hides, bones)
Likely to develop Cutaneous and pulmonary anthrax ( inhalation)

21. Cutaneous Anthrax
• Mainly in professionals( Veterinarian, butcher, Zoo keeper
• Spores infect skin- a characteristic gelatinous edema develops at
the site (Papule- Vesicle-Malignant Pustule- Necrotic ulcer)
• 80-90% heal spontaneously ( 2-6wks)
• 0-20% progressive disease – develop septicemia
• 95-99% of all human anthrax occur as cutaneous anthrax
Intestinal Anthrax
• Due to ingestion of infected carcasses
• Mucosal lesion to the lymphatic system
• Rare in developed countries
• Extremely high mortality rate

22. PULMONARY ANTHRAX
• Require very high infective dose ( > 10,000 spores)
• Acquired through inhalation of spores ( Bioterrorism - aerosol)
• Present with symptoms of severe respiratory infection( High fever
& Chest pain)
• Haemorrhagic mediastinitis
• Progress to septicemia very rapidly
• 10 7 to 10 9 bacilli/ ml of blood at the time of death
• Mortality rate is very high > 95%

23. LABORATORY DIAGNOSIS
Few points to remember
• Anthrax is not highly contagious
• Cutaneous anthrax is not lethal and is readily treated with
common antibiotics
• ID for human pulmonary / intestinal infection is > 10,000 spores
SPECIMEN TO COLLECT ( HUMAN ANTHRAX)
Disposable gloves, masks, overalls, boots, head gear and dust mask
Disposable items – Autoclave and incinerate
Cutaneous anthrax: Vesicular exudate – swabs and capillary tube aspirate
Intestinal anthrax: - Stool sample - isolate – guinea pig inoculation
- Blood( venipuncture) smear examination for bacilli
- Peritoneal fluid for culture
- Paired sera for Ab
Pulmonary anthrax: Severely ill – Blood , sputum, serum samples for Ab

24. IMMUNITY TO ANTHRAX
Resistance against anthrax vary from species to species
- Human are partially immune to anthrax
Resistance can be of two types
- Resistance to the establishment of infection but
sensitive to toxin
- Resistance to toxin but susceptible to infection
Animals surviving naturally acquired anthrax are immune to
reinfection
Protective antibodies against the anthrax toxin and against the
capsule
BImal K Das, Microbiology, AIIMS

25. TREATMENT
Antibiotics should be given to unvaccinated individuals
exposed to inhalation anthrax.
Penicillin, tetracyclines and fluoroquinolones are effective
if administered before the onset of lymphatic spread or
septicemia
Antibiotic treatment is effective in cutaneous anthrax
Inhalation anthrax can be effectively treated with
antibiotics administered prior to lymphatic spread or
septicemia

26. INITIAL THERAPY OPTIMAL THERAPY
Adults Ciproflox Penicillin G 4 mu iv qid X 60days
( 400mg iv BD X 60days) Doxycycline 100mg iv BD X 60 days
Children Ciproflox
20-30mg/kgbodywt iv X 60days Penicllin G 50,000 IU/kg X 60 days
Alternatives – Amox, Tetracycline, Chloramphenicol, Erythromycin, Streptomycin

27. Vaccine against Anthrax
Killed bacilli and/or capsular antigens produce no significant
immunity.
A nonencapsulated toxigenic strain (Sterne Strain) has been
used effectively in livestock.
Vaccine for humans: ( avirulent and nonencapsulated)
sublethal amounts of the toxin produced
Licensed in the U.S. is a preparation of the protective
antigen (PA)
Dose: A. 3 doses subcutaneously at the interval of 2 wks
B. Followed by three additional doses at 6,12 and 18
months
C. Annual booster dose

28. Who are to be vaccinated
- Professionals ( Veternarians, butcher,
Zoo keeper, Wild life workers, Forest
guards)
- Military personnels