This document summarizes pathogens associated with foodborne illnesses in developing countries. It notes that national surveillance programs are generally lacking in developing nations. The main pathogens discussed are bacteria (Salmonella, Shigella, Campylobacter, E. coli), viruses (Hepatitis A, Norovirus, Rotavirus) and parasites (Entamoeba histolytica, Giardia lamblia, Cryptosporidium). Specific Salmonella, Shigella, and Campylobacter serotypes found in different developing countries are also outlined. The document concludes by discussing sources and resistance of these pathogens.

1. Pathogens-Associated with Foodborne
Illnesses in Developing Countries
Prof. Khalifa Sifaw Ghenghesh
Dept. of Microbiology and Immunology,
Faculty of Medicine, Tripoli University,
Tripoli Libya

2. Introduction
National surveillance programs for
pathogens associated with foodborne
illnesses generally do not exist in most
developing countries despite the
substantial burden of disease.
Most estimates of incidence in developing
countries are from laboratory-based
surveillance of pathogens responsible for
diarrhea.

3. Pathogens-associated with
foodborne illnesses
 Bacterial:
 Bacillus cereus
 Campylobacter sp.
 Clostridium botulinum
 Clostridium perfringens
 Diarrheagenic
Escherichia coli:
E. coli O157:H7
 Listeria monocytogenes
 Salmonella sp.
 Shigella sp.
 Staphylococcus aureus
 Vibrio cholerae
 Yersinia sp.
 Viral:
 Hepatitis A
 Norovirus
 Rotavirus
 Parasitic:
 Entamoeba histolytica
 Giardia lamblia
 Cryptosporidium sp.

4. Salmonella
S. typhi and S. paratyphi
 Typhoid fever
Non-typhoid Salmonella
 Salmonellosis
 > 2,000 named serotypes (serovars).
Based on iso-enzymes, rRNA sequences, and
DNA hybridization, it is generally accepted now
that there is only a single species of Salmonella
> S. enterica
 > S. enterica serotype Typhimurium
 Most common:
S. Enteritidis > in developed countries
S. Typhimurium
S. Heidelberg?

5. Shigella
Shigellosis
4 Major O Antigenic Groups:
Serogroup A = Sh. dysenteriae
Serogroup B = Sh. flexneri
Serogroup C = Sh. boydii
Serogroup D = Sh. sonnei :

6. Campylobacter
Campylobacteriosis:
 > 16 species
C. jejuni and C. coli

7. Salmonella, Shigella and Campylobacter
in Developing Countries

8. Isolation rates of Salmonella, Shigella and Campylobacter
from diarrhea specimens from children in selected
developing countries















Argentina
Bangladesh
Brazil
Egypt
Guatemala
Indonesia
Jordan
Kuwait
Lao PDR
Libya
Pakistan
Saudi Arabia
Thailand
Tunis
Zimbabwe
Isolation rate (%)
Salmonella
Shigella
Campylobacter
2.4
8.5
3.2
1.8
9.2
17.4
2.2
6.2
5.4
7
5
7
NA
9.8
12.1
2.5
4.2
0.4
3.9
8.3
5.6
24
4
7
0.6
16.8
4.4
11
5.7
6.3
6.6
6.2
17.3
10.5
17.1
NA
12
13
13
2.4
4.1
4.7
5.4
13.5
1.3

9. Distribution of Salmonella serotypes:
 S. Typhimurium
 S. Enteritidis
 Other serotypes:
Differs from one country to another

10. Salmonella Serotypes Isolated from Diarrheic Faeces
in Tripoli (1975-1980)
S. Wien
S. Muenchen
S. Typhimurium
Salmonella Serotypes Isolated from Children with
Diarrhea in Tripoli (1992-1993)
S. Saintpaul
S. Muenchen
Salmonella Serotypes Isolated from Children with
Diarrhea in Zliten (2000-2001)
S. Heidelberg
S. Enteritids

11. Distribution of Shigella groups:
 Sh. flexneri
Distribution of Campylobacter species:
 C. jejuni and C. coli are the two main species
isolated in developing countries.
 Similar to observations in developed countries, the
isolation rate of C. jejuni exceeds that of C. coli.

12. Age of Infection:
 Most commonly isolated from <2-year-old children with
diarrhea.
 Shigella?
Polymicrobial Infections:
 Campylobacter > common
Isolation in Healthy Children:
 Campylobacter > common
 Shigella > rare

13. Seasonal Variation:
 Contrary to developed countries, diarrhea due to
Salmonella, Shigella or Campylobacter, has no
seasonal preference in developing countries.
 Lack of seasonal preference may be due to:
lack of extreme temperature variation
lack of adequate surveillance for epidemics.
Association with travelers' diarrhea:
 Travel to a developing country is a risk factor for
acquiring Salmonella-, Shigella- or Campylobacterassociated diarrhea.
 The diarrhea is more severe, and strains are
associated with antibiotic resistance.

14. Antibiotic resistance in Salmonella, Shigella
and Campylobacter isolates:
 Resistance is high in developing countries.
 Salmonella and Campylobacter enteritis are selflimiting diseases, and antimicrobial therapy is not
generally recommended.
 Shigella
Patients respond to antibiotics.
disease duration diminished.

15. Resistance of Salmonella species isolated from
children with diarrhoea in Zliten (2000- 2001)
to antibiotics
Antibiotic
No. (%) resistant:
(n=23)
--------------------------------------------------------------------------------Ampicillin
23 (100)
Amoxicillin+calvulanic acid
22 (95.7)
Cefoxitin
20 (87)
Gentamicin
18 (78.3)
Doxycycline
21 (91.3)
Chloramphenicol
22 (95.7)
Nalidixic acid
1 (4.3)
Norfloxacin
0 (0.0)
Trimethoprim-sulphamehtoxazole
1 (4.3)
_________________________________________________

16. Sources of Salmonella, Shigella and
Campylobacter
Shigella and S. Typhi:
Man is the only reservoir.
Campylobacter and non-typhoid Salmonella:
 Animals products:
Chicken
eggs
Meat
Dairy products
Others:

17. Total bacterial and coliform counts and pathogenic
bacteria isolated from ice cream sold in Tripoli—Libya
Ice cream
Bacteria
Open
Packed
Total
(n = 111)
(n = 49)
(n = 160)
--------------------------------------------------------------------------------------------------E. coli
7 (6)a
3 (6)
10 (6)
Salmonella sp.
7 (6)
1 (2)
8 (5)
Shigella sp.
Absent
Absent
Absent
Aeromonas sp.
20 (18)
10 (20)
30 (19)
S. aureus
41 (37)
19 (39)
60 (38)
L. moncytogenes
7 (6)
Absent
7 (4)
--------------------------------------------------------------------------------------------------a
No. (%) positive.

18. Bacteria isolated from the houseflies collected
in Misurata - Libya
Collection site:
Bacteria
Central Hospital City streets Abattoir
All
(n=50)a
(n=50)
(n=50)
(n=150)
----------------------------------------------------------------------------------------------------------------Escherichia coli
21 (42)b
21 (42)
16 (32)
58 (38.7)
Salmonella sp.
0 (0)
3 (6)
1 (2)
4 (2.7)
Shigella sonnei
0 (0)
0 (0)
1 (2)
1 (0.7)
Yersinia enterocolitica 0 (0)
2 (4)
1 (2)
3 (2.0)
Edwardsiella tarda
0 (0)
2 (4)
1 (2)
3 (2.0)
Aeromonas sp.
1 (2)
10 (20)
5 (10)
16 (10.7)
Pseudomonas sp.
48 (96)
18 (36)
17 (34)
78 (52)
Pasteurella sp.
0 (0)
1 (2)
2 (4)
3 (2.0)
Staphylococcus sp.
10 (20)
6 (12)
8 (16)
24 (16.0)
Streptococcus sp.
12 (24)
11 (22)
9 (18)
32 (21.3)
--------------------------------------------------------------------------------------------------------------a
No. of flies investigated
b
No (%) positive