CHAPTER ONE

INTRODUCTION

1.1 Background

Salmonella infection is a common global cause of enteric fever such as typhoid, a disease responsible for about 20 million episodes of illness and over 200,000 deaths annually globally (Jin et al.,2017). Typhoid, which is a disease caused by Salmonella typhi, is an acute illness characterized by high fever, malaise, a self-limiting diarrhea, nausea, chills, headache, bradycardia, hepatosplenomegaly, delirium, psychosis, focal neurological deficit, septicemia, bowel perforation and even death (Klochko  et al.,2018). Salmonella species causes systemic infection during which the pathogen colonizes the intestine and mesenteric lymph node, the liver, spleen, bone marrow and gall bladder (Parry and Dougan, 2020).

Salmonella was first discovered from pigs in 1880 by Daniel Elmer Salmon, an American veterinary pathologist and Theobald Smith. In 1890. the organism was named after D.E. Salmon to honor him (Ziprin et al.,2014). During the course of treatment of a typhoid outbreak in a local village in 1838. English country doctor William Budd realized that there were “poisons” in the infectious disease of the people and this poison was multiplying in their intestines and also were present in the excretions and could be transmitted to healthy individuals through their consumption of contaminated water (Pollack et al.,2013). He further proposed strict isolation or quarantine as a method of containing the outbreak in the future. The medical and scientific community did not identify the role of microorganisms in infectious diseases until the work of Robert Koch, Daniel Elmer Salmon. Karl Eberth and Eouis Pasteur which resulted to the discovery and isolation of Salmonella bacteria; named after D. E Salmon (Pollack et al.,2013).

Acuno- Soto et al., (2012) wrote about a pair of epidemics stroked the Mexican highlands in 1545 and 1576. causing an estimated 7 to 17 million deaths in the sixteenth and the seventeenth centuries. Later a study published in 2018 revealed that the cause of the epidemic was typhoid fever (Hersher et al.,2018). Some historians believe that the English colony of Jamestown, Virginia, died out from typhoid. Typhoid fever killed more than 6.000 settlers in the new world between 1607 and 1624. In the nineteenth century, the ninth and twelfth US presidents were believed to have died from typhoid infection due to the poor sanitary conditions in Washington DC in the mid- 19lh century (Mcl et al.,2014). Mary Mallon (also known as Typhoid Mary) in 1907 became the first most notorious carrier of typhoid fever in the United States to be identified and traced. She was a cook in New York and was closely associated with 53 cases and 3 deaths.

Enteric fever caused by Salmonella species affects only humans (who are the reservoir) and is spread through consumption of contaminated food and drink handled by people who shed the organism from stool or, less commonly, urine (Reddy et al.,2011). It may also be acquired from ingesting water contaminated with sewage. Food needs to be heavily contaminated for infection to occur- approximately 103 to 109 cells may be required to cause illness (Reddy et al.,2011).

Diarrheal disease continues to be an important cause of morbidity and mortality in developing countries and globally, intestinal parasites, and Salmonella species remain major contributors to acute enteric infections (Ishaleku et al., 2015). Worldwide, enteric fever is most prevalent in impoverished areas that are overcrowded with poor access to sanitation. Incidence estimates suggest that south-central Asia. Southeast Asia, and southern Africa are regions with high incidence of Salmonella species infection (more than 100 cases per 100,000 person-years) (Buckle el al.. 2012; GBD, 2017). Other regions of Asia and Africa, some parts of Latin America, the Caribbean, and Oceania have a medium incidence of 10 to 100 cases per 100,000 person-years. These estimates, though, arc limited by lack of ‘consistent reporting from all areas of the world and arc based on extrapolation of data across regions and age groups. More recent population-based studies from Latin America, in particular, are lacking, and surveillance suggests that rates have declined substantially over the past 30 years.

Furthermore, subsequent data from Africa have revealed substantial heterogeneity between countries, with some Southern and Northern African countries having very low’ rates (<5 cases per 100.0           person-years) while several countries in lantern and West Africa have rates >100 per 100.0        (Marks et al., 2017).

enteric infections like Salmonella species are widespread diseases affecting the population in Cameroon (Crump and Mint/.. 2010) with prevalences reported to range between 6 and 39 (Ndip et a/.. 2015; Awung et al.,2018; Warn el al.,2019). Poor personal and environmental hygiene, waste disposal as w’ell as consumption of food sold by unhygienic commercial vendors have been implicated as major factors that encourage stable transmission (Crump et al,2010).

Although, with adequate treatment, most patients recover from the acute phase of the Salmonella

infection. Some Salmonella species can persist asymptomatically within the gall bladder and

enteric following clinical recovery. Overall, 10% of those infected will carry Salmonella species within their gall bladder for up to 3 months, while 1 to 3% will continue to harbor it for longer than 1 year in the enterics (Gal et al.,2014).

1.2 Problem Statement         

The prevalence of Salmonella disease has been on an increase in Cameroon. This was shown in a cross-sectional study that was carried out by Nsutebu et al., (2013) to determine the prevalence of typhoid fever in 200 consecutive patients with fever and symptoms clinically compatible with Salmonella fever to verify recent estimates of a high prevalence of Salmonella disease fever in Cameroon. Salmonella disease was confirmed in 2.5%. This trend tends to increase when Ndip et al., (2015) found the prevalence of Salmonella infection in South West Cameroon to be 6.75% which showed a recognizable high endemicity rate. Meanwhile, Awung et al., (2018) found an increased prevalence of 9.8% in the same South West Cameroon.

1.4 Since this disease leads to a lot of deaths, morbidity and usually predisposition to other diseases like gastrointestinal ulceration (Ray et al.,2015), it has therefore become necessary to explore the occurrence of Salmonella species infection and its associated risk factors among patients leading to an effective public health management and control.

1.3 Rationale of the Study

The result of this study will add to the body of knowledge, provide insight to current infection pattern of ‘the disease on which future control strategies can be based. In addition, this study would be beneficial to the Cameroon Ministry of Public Health, Non-Governmental Organizations and the general public by providing a current baseline data for planning, epidemiological studies, control programs and enlightenment

1.4 Research Questions

1. What is the prevalence of Salmonella infection among symptomatic patients attending the Mount Mary Hospital of Buea?
2. What is the prevalence of Salmonella infection in relation to gender and age among symptomatic patients attending the Mount Mary Hospital of Buea?

iii. What is the distribution of Salmonella infection across the risk factors among symptomatic patients attending the Mount Mary Hospital of Buea?

1.5 Research Objectives

1.6.1 General Objective

To determine the prevalence of Salmonella infection and associated risk factors among symptomatic patients attending the Mount Mary Hospital

1.6.2 Specific Objectives

1. To determine the prevalence of Salmonella infection among symptomatic patients attending the Mount Mary Hospital of Buea.
2. To determine the risk factors of Salmonella infection in relation to gender and age groups among symptomatic patients attending the Mount Mary Hospital of Buea.

iii. To determine the distribution of Salmonella infection across the risk factors among symptomatic patients attending the Mount Mary Hospital of Buea.