Risk of exposure to campylobacter through consumption of ready-to-eat
roast beef and poultry meat in informal outlets in Arusha municipality.
Mahundi E1, Makita K2,3, Toyomaki H3, Grace D2 and Kurwijila LR4
1
Tanzania Food and Drugs Authority, Tanzania,2International Livestock Research Institute (ILRI), Kenya 3Rakuno Gakuen University, Japan4 Sokoine University of Agriculture, Tanzania
1. Message:
Hygienic roasting of the meat reduces the risk of campylobacteriosis.
2. Introduction:
Campylobacteriosis is a widespread infection caused by a group of bacteria called
Campylobacter. Livestock animals and poultry are the main source of campylobacteriosis
as they carry some of the species in the bowel without themselves being ill. The disease
is transmitted by eating raw meat, insufficiently cooked meat or drinking raw milk
contaminated with bacteria.
Figure 1: Beef (mishikaki/Nyamachoma) being grilled before serving on table
3. Materials and Methods: Beer bars serving ready to eat beef were surveyed:
45 roast beef (nyamachoma) and 42 skewer beef (mishikaki) were collected and cultured for thermophilic Campylobacter. The owners were
interviewed for average sales per day. The second survey was conducted in September 2010 to obtain the most probable number (MPN)
of Thermophilic Campylobacter and additional information on sales. One sample per beer bar was collected and in total 30 roast beef
and 10 chicken samples were examined. The samples were cultured and PCR was performed to confirm the isolates as either C. jejuni or C.
coli. A risk model was developed based on the survey data and dose-response relationship was modeled using medical records obtained
from another study and literatures (Table 1). A monte carlo simulation was run for 5,000 iterations and sensitivity analysis was run for 500
iterations.
Parameters Distributions Description
Prevalence of thermophilic Campylobacter in roast beef Beta (s+xi , n-si+yi) Prior is Beta (x, y) from the first survey. i shows strata (Northern and Southern wards). n
includes both beef and chicken.
Cfu/g of Campylobacter in roast beef LogNormal (μ, SD) Second survey data
Number of beer bars serving roast beef Point estimate First survey data
Daily beef sales Bootstrap First survey data
Nyamachoma consumption pattern Discrete (quantity, proportions) Second survey, interview
Mishikaki consumption pattern Bootstrap First survey, interview
Dose-response Beta-Poisson model Black et al. (1988)
Immunity for Campylobacter Ratio of ratios of over and below 5yrs in Uganda and Japan Makita K. (2009) Obana et al. (2002)
Population in Arusha Municipality 341,136 Arusha Municipality Office
Table 1. Parameters and distributions used in the risk modeling
4. Results:
Table 2 shows prevalence of T. Campylobacter in Nyamachoma and mishikaki obtained in beer bars. Note higher isolation rates in almost all
products in the southern wards. However, the second survey found only one positive sample in roast chicken contaminated with C. coli out
of 10 samples in PCR and none of 30 roast beef samples out of 30 was contaminated with C. jejuni or C.coli
Type of Product Ward No. Sampled No. positive Prevalence (%)
Nyamachoma Northern 21 1 5
Southern 24 7 31.6
Mishikaki Northern 20 3 15
Southern 20 7 35
Table 2. Prevalence of thermophilic Campylobacter from the first survey using conventional microbiology
Parameters Statistics
Daily incidence rate among customers per 1000 people 12.5 (90%: 4.7-22.8)
Annual incidence rate in Arusha per 1000 people 168.8 (90%CI: 67.4-300.0)
Annual incidence rate in Arusha per 1000 people using PCR based prevalence 107.0 (90%CI: 32.7-215.0)
Table 3: Monte Carlo simulation for risk characterization run at 5000 iterations
5. Discusion:
Northern Zone has lower exposure rate because are resided by wealthier people, where as Southern wards are resided by poor society.
Even with prevalence by PCR, significant number of cases should be there. The most sensitive parameter is cfu/g and this cfu/g is based on
single positive sample. Additional survey in future may give more precise figure. Hygiene training should be advocated to reduce cross
contamination after roasting.
6. References
Black RE et al., 1988. Experimental Campylobacter jejuni infection in humans. J Infect Dis 157, 472-479.
Makita K., 2009. PhD Thesis. The University of Edinburgh.
Obana M et al., 2002. Recent trend of infectious enteritis- from reports between 1996 and 2000. J Japan. Assoc. Inf. Dis. 76 (5): 355-67.
Acknowledgements:
Financial support from ILRI through SFF 1, ASARECA and Rakuno Gakuen University project. TFDA and SUA are also acknowledged
For more information contact;
Tel: +255 654 81 7849  Fax: +255 22 2450512  E-mail: mahundieabc@yahoo.com  Website www.tfda.or.tz