Analysis of Listeriosis Transmission Dynamics with Optimal Control

Listeriosis is an illness caused by the germ Listeria monocytogenes. Generally, humans are infected with listeriosis after eating contaminated food. Listeriosis mostly affects people with weakened immune systems, pregnant women and newborns. In this paper, a model describing the dynamics of Listeriosis is developed and analysed using ordinary differential equations. The model was analysed both quantitatively and qualitatively for its local and global stability, basic reproductive number and parameter contributions to the basic reproductive number to understand the impact of each parameter on the disease spread. The Listeriosis model has been extended to include time dependent control variables such as treatment of both humans and animals, vaccination and education of humans. Pontryagin’s Maximum Principle was introduced to obtain the best optimal control strategies required for curbing Listeriosis infections. Numerical simulation was performed and the results displayed graphically and discussed. Cost effectiveness analysis was conducted using the intervention averted ratio (IAR) concepts and it was revealed that the most effective intervention strategy is the treatment of infected humans and animals.

Listeriosis Knowledge and Attitude among Pregnant Women Attending a Tertiary Health Institution, South Western Nigeria

Background: Listeriosis affects immunosuppressed individual’s especially pregnant women. Maternal infections are usually mild for the woman, but may have devastating effects on the unborn child, including miscarriage, stillbirth, preterm labour and serious neonatal illness. WHO recommends that pregnant women should be educated to avoid foods with high risk of contamination. This study seeks to evaluate knowledge and practices predisposing to listeria infections during pregnancy. Methodology: This is a cross-sectional study on pregnant women, attending the antenatal clinic of Lagos University Teaching Hospital (LUTH) using semi structured questionnaires. The knowledge score of participants was collated and analyzed using SPSS version 26. Results: The mean age of the participants was 32.07 ± 5.6 years. Forty-three (30.7%) women have had previous miscarriages with the mean no of miscarriage of 1.54. Out of 147 participants, only 20 (13.6%) admitted having heard of listeriosis while 127 (86.4%) had never heard of listeriosis and none of the participants has ever been tested for listeriosis. The Overall knowledge score was poor, and this was irrespective of age and duration of pregnancy. However, women with graduate and/or postgraduate degrees were more likely to have heard of Listeriosis (X2 = 10.88, P = 0.028). Conclusion: Our study shows a low level of knowledge about this food-borne illness, which can lead to severe illnesses in pregnant women and their unborn child. It is necessarily to educate pregnant women on the risk of listeriosis. This would be a key factor in creating and implementing accurate measures of prevention and control.

Prevalence and molecular characteristics of Listeria monocytogenes in cooked products and its comparison with isolates from listeriosis cases

This study aimed to investigate the prevalence and molecular characteristics ofListeria monocytogenes in cooked products in Zigong City, China. The overall occurrence of the L. monocytogenes in the ready-to-eat （RTE） shops and mutton restaurants surveyed was 16.2% （141/873）. An occurrence of 13.5% was observed in RTE pork, 6.5% in RTE vegetables, and more than 24.0% in either cooked mutton or cooked haggis. Serotype 1/2b （45.4%）, 1/2a （33.3%）, and 1/2c （14.2%） were the predominant types. By comparing the clonal complexes （CCs） based on multilocus sequence typing （MLST） of the L. monocytogenes from cooked foods in Zigong City and 33 listeriosis cases from different districts of China, CC87, CC9, CC8, and CC3 were showed to be prevalent in cooked products and CC87 and CC3 were the first two frequent types in the 33 clinic-source strains. All CC87 stains harbored the newly reported Listeria pathogenicity island 4 （LIPI-4） gene fragment ptsA, and all CC3 strains possessed the Listeria pathogenicity island 3 （LIPI-3） gene fragment llsX. These may increase the occurrence of the strains belonging to CC87 and CC3 in listeriosis cases in China and also underline the risk of infection owing to the consumption of the cooked products from Zigong. ST619 （serotype 1/2b） harbored both llsX and ptsA, indicating a potential hypervirulent sequence type in Zigong.

Occurrence of Multi-Drug Resistant <i>Listeria species</i>in Faecal Samples of Poultry Chickens in Rural Farms in Lagos State, Nigeria

Background: Listeriosis is a common zoonotic disease caused by a foodborne pathogen, Listeria monocytogenes. Poultry meat and products have been established as vehicles of transmission of pathogenic Listeria strains to humans. This study evaluates the occurrence of Listeria species in faeces of poultry chicken in Lagos. Methods: One hundred and fourteen pooled fresh faecal samples from cage-reared broiler chickens were collected from 12 farms in three rural areas in Lagos State from May to August 2019. All samples were analysed for Listeria species detection according to ISO11290-1 standard and confirmed using PCR assay. Susceptibility testing was performed using the Kirby-Bauer disc diffusion technique. Results: Twenty-eight (24.6%) Listeria species were detected from 114 faecal samples. The isolated Listeria species were L. monocytogenes 8 (7.0%), L. ivanovii 9 (7.9%), L. grayi 7 (6.1%) and L. innocua 4 (3.5%). There was no significant difference in the frequency of occurrence of Listeria species across the different locations (X2 = 4.98, p = 0.08). The listeria species were susceptible to Augmentin (96.4%), vancomycin (85.7%) and co-trimoxazole (82.1%), but resistant to ceftazidime (100%), tetracycline (75.0%) and ciprofloxacin (71.4%). Conclusion: This study reveals high occurrence of multi-drug resistant Listeria species in faecal samples of poultry chickens in Lagos state which may be an important vector in the contamination of the environment and transmission of antibiotic resistant Listeria species to consumers.

Systematic review of Listeria monocytogenes from food and clinical samples in Chinese mainland from 2010 to 2019

Listeria monocytogenes(L.monocytogenes),a foodborne pathogen,can cause human listeriosis.Listeriosis is a potentially fatal gastrointestinal illness,which is closely related to the spread of food to humans.We review the literature published during 2010-2019 to better understand the prevalence of L.monocytogenes in food products,incidence of human listeriosis,and their characteristics in Chinese mainland.We found the main sequence types(STs)strains from foods are similar globally,and the prevalence of L.monocytogenes from raw meat was the highest among all food products.The most common STs in food products and clinical cases were ST9(serogroup I.2)strains and ST87(serogroup Il.2)strains,respectively.The ST87 strains being the most common STs of clinical cases might be related to the existence of Listeria pathogenicity island 4 gene and Chinese eating habits for ready-to-eat foods,among which the prevalence of ST87 strain was the highest in ready-to-eat foods.Therefore,more research should be conducted to explore the reasons for the L.monocytogenes isolates differences in food and clinical sources.