EMERGING TICK-BORNE PATHOGENS OF PUBLIC HEALTH IMPORTANCE

1.1 Introduction

Ticks are second to mosquito vectors of diseases to humans (Røed et al., 2006). Diseases transmitted by ticks occur as natural foci and their range is equivalent to the geographical spread of certain species of ticks (Cisak et al., 2012). In Europe the most common tick is Ixodes ricinus, which most predominantly infects humans (Bartosik et al., 2011). The status, distribution and abundance of the main tick species are implicit requirements for the risk assessment of tick-borne infections of pathogen in humans. The risk of attack is increased while staying for occupational or recreational purposes in tick habitats during their seasonal activity (Bartosik et al., 2011). Currently, individual aspects of tick activity as well as the distribution of risk areas suggest an influence of the climate (Suss, 2010). Ticks are detected in their habitats by flagging method or by blanket dragging (Welc-Falęciak et al., 2012; Bartosik et al., 2011). Eastern and south-eastern Poland is the area of high risk of infections by tick-borne pathogens (Bartosik et al., 2011).

As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Research hypothesis and questions, Limitations of the Study and Definition of technical terms.

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1.2 Background of Study

Over past decades, tick-borne encephalitis (TBE) has become a growing public concern in Eastern and Central Europe and in Asia. It is regarded as one of most important and life-threatening human infections of the central nervous system, causing annually thousands of cases (Wójcik-Fatla et al., 2011; Suss et al., 2010; Cisak et al., 2010; Cisak et al., 2012). Since 1990, the increase in the incidence of TBE has been observed, probably due to the elevated number of infected vectors and their increased activity (Wójcik-Fatla et al., 2011). During past twenty years the number of reported cases of TBE in Poland has ranged from 100 to 250 cases per year (Suss et al., 2010). The most important risk areas are located in the northeast of the country. In southern Poland and in Silesia, highly endemic areas were found around Opole and Stalowa Wola. There are also a few small areas in Poland where the virus appears to be rare (Suss et al., 2010).

Humans are normally infected through tick bites or after direct contact with blood or tissue from viraemic humans or animals, and clinical disease is characterised by a haemorrhagic fever (Ergonul 2012). Tick-borne illnesses have a substantial economic burden, which is only becoming worse year after year. In 2002, the estimated cost of treating individuals with Lyme disease only in the United States were USD $8172 per patient, which is equivalent to USD $11 838 in 2019. More than $500 million is estimated to be spent each year by the Centers for Disease Control and Prevention (CDC) depending on the 42 743 cases recorded in 2017. Patients with post- treatment Lyme disease syndrome may have to pay even more (Adrion et al., 2015). One-fourth of Lyme disease patients get public assistance or disability assistance, which places a significant financial burden on society. The hotel and tourist business in the endemic regions is subjected to extra economic expenses that are large but difficult to measure (Donohoe et al., 2015). Lyme disease's impact on public health isn't limited to the United States. Several European governments have spent tens of millions of euros treating Lyme disease, according to a recent thorough assessment.

The total public health burden of all illnesses transmitted by ticks is still largely unquantified (Johnson et al., 2011). Aside from human tick-borne illnesses, veterinary tick-borne diseases have the potential to be devastating, particularly for those living in underdeveloped nations (Estrada-Peña et al., 2013). At an expected cost ranging from $13.9 billion to $18.7 billion USD, 80% of the planet's cattle herd is at risk of contracting a tick-borne illness. About 1.3 million cattle died from theileriosis (68%), babesiosis (13%), and anaplasmosis (13%), in Tanzania, a country where the economic damages caused by tick-borne illness have been measured (Oakes et al., 2019). Ticks are now attracting the interest of a wider spectrum of public health specialists due to the growth in tick populations and the rising prevalence of illnesses transmitted by ticks. This review aims to outline the most recent achievements in tick-borne illnesses, with a focus on newly identified or emerging diseases globally that constitute a public health issue (Rainey et al., 2018).

Infection rates in the principal tick vectors have been reported to be as high as 100% (Parola et al. 2005). The aggressive nature of the questing Amblyomma spp. ticks increases the risk of infection in people who frequent pastures and game areas (Althaus et al. 2010). There have been several reports of human infections in people who had visited game reserves (Althaus et al. 2010; Consigny et al. 2005; McQuiston et al. 2004).

Borrelia duttonii is transmitted by Ornithodoros moubata (Cutler 2010). An enzootic cycle in which a vertebrate reservoir species and the tick vectors serve as a ready source of infection for humans has not been demonstrated for B. duttonii (Cutler 2010). TBRF is endemic in the DRC and Tanzania, but has not been reported further south. In Tanzania it is listed amongst the top 10 killer diseases in children under 5 years of age (Cutler 2010), associated with perinatal mortality of up to 436/1000 (McConnell 2003). In the DRC, infection was associated with adverse outcomes, including mortalities, especially in pregnant women (Dupont et al. 1997).

Therefore, in Nigeria where the research was carried out, the activities that was conducted is to know the Emerging Tick-Borne Pathogens of Public Health Importance.

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1.3 Statement of Problems

Investigation revealed that vector-borne diseases have long been a problem for both animals and humans, causing some of the worst plagues of mankind, such as the Black Death in Europe in the 14th century and yellow fever epidemics in the Americas (Gubler 2009). The 20th century witnessed a steady decline in vector–borne diseases through the implementation of extensive vector control programmes, but the 21st century has witnessed the re-emergence of some of these diseases. This re-emergence has been presumed to be because of new global trends in animal husbandry, urbanisation, modern transportation and globalisation (Gubler 2009). Amongst the re-emerging vector-borne diseases are tick-borne diseases (Estrada-Peña, Ayllon & De la Fuente 2012).

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1.4 Aim and Objectives of Study

The aim of the study is to identify the Emerging Tick-Borne Pathogens of Public Health Importance. In achieving this aim, the following specific objectives were laid out as follows:

1. To provide preliminary information on the tick-borne pathogens of potential zoonotic importance present in Nigeria;
2. To investigate the effect of tick-borne pathogens on public health;
3. To identify tick species and their feeding duration; and
4. To understand the best treatment procedures for tick-borne pathogens.

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1.5 Research Questions

The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:

• What are tick species and their feeding duration?
• What is the effect of tick-borne pathogens on public health?
• What are the best treatment procedures for tick-borne pathogens?

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1.6 Significance of Study

Ticks are important vectors that can transmit various pathogens, such as viruses, and basically those can cause neurologic and hemorrhagic health problems. This study will be of immense benefit to researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.

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1.7 Scope of the Study

The scope of the research is focused on the Emerging Tick-Borne Pathogens of Public Health Importance in Nigeria.

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1.8 Limitations of the Study

During the course of this study, many things militated against its completion, some of which are:

1. Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
2. Research material: availability of research material is a major setback to the scope of the study.
3. Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
4. Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).