Challenges and Constraints in Disease Control

Introduction

Historically, there has been a lack of support from the Kurdistan government for the control of diseases of sheep and goats in Dohuk Province, and this, combined with a lack of information about brucellosis and toxoplasmosis in sheep and goats in the province, has resulted insufficient progress in the control of these two diseases. In addition, veterinary staff in Iraq are suffering from a lack of infrastructure, material and funds, inadequate security, lack/unreliability of electrical supply, problematic logistics and transport (Alshwany, 2019). The war in Iraq causes significant challenges for the surveillance and control of communicable disease (Valenciano et al., 2003). Until now, lack of security stays to be a barrier for effective public health surveillance and response in Iraq (Valenciano et al., 2003). As Maxwell and Bill (2008) mentioned, prior to the research reported in this thesis, most surveys conducted on brucellosis and toxoplasmosis in small ruminants in Iraq were not undertaken by using sound scientific epidemiological methods, and therefore their results are questionable.

The studies outlined in this thesis were designed to acquire more information about the epidemiology of brucellosis and toxoplasmosis in sheep and goats in Dohuk province so that. When sufficient resources become available, a scientifically sound control programme could be developed and implemented. This initially involved undertaking a cross-sectional seroprevalence study, followed by research to assess putative risk factors for both the diseases; evaluate the economic burden of brucellosis in small ruminants, and determine the incidence of seroconversion to Brucella and Toxoplasma and the relationship between seroconversion to these pathogens and maintenance of pregnancy in sheep and goats in Dohuk Province.

Seropositivity and risk factors of Brucella melitensis

Brucellosis is considered as an important public health disease in most Middle East countries, due to similar environmental conditions, livestock management and husbandry systems and cultural practices in countries within the region (Refai, 2002; Gwida et al., 2010). Brucellosis is responsible for significant economic losses to the small ruminants industry because of abortion, reduced milk production, premature birth, and decrease reproduction rate (Ganter, 2015). In 2014, the Kurdistan province in Iran had the highest human brucellosis – related DALYs (2.93 per 1000 population) (Piroozi et al., 2019). Another researcher estimated a DALY of 27.17 per 100,000 persons per year in Kurdistan (Alshwany, 2019). The production loss is the essential factor leading to the economic losses due to brucellosis. All the patients suffering from brucellosis need medical attention as the disease is quite nasty and painful (Nicoletti, 2001). Human brucellosis was estimated to cause an annual median loss of 10.45US$ (95% CI: 8.91-12.35 US$ million) in India (Singh et al., 2018a). The incidence of Brucella melitensis in humans in Iraq has been estimated to be between 52.3 cases per 100,000 person-years in a rural area and 268.8 cases per 100,00 person-years in a semi-rural area (Yacoub et al., 2006).

Identifying and understanding the risk factors for disease are critical for the implementation of an effective disease control programme (Porphyre et al., 2010). In general, the risk factors for zoonotic disease transmission of brucellosis are well documented in many parts of the world, including Iraq and other Middle Eastern countries (John et al., 2010). The challenge is to find mitigation strategies that are easy to implement and which simultaneously enable livestock owners to benefit from disease control whilst ensuring the health of farmers and their families along with the workers in high risk occupation and consumers (Schelling et al., 2007).

In this study (Chapter 4), two tests (RBT and iELISA) were utilised to confirm infection with Brucella spp. with the results interpreted in parallel to improve the sensitivity of detection (Sanogo et al., 2012). The seroprevalence using these tests was 31.7% (95% CI: 26.1, 36.3) for sheep and goats (Chapter 4). Although this was higher than the 16.4 % reported by Salih (2010) in sheep and goats in Kirkuk province in Iraq, the disease is still likely to be having an economic impact on the productivity (chapter seven) and the current level of vaccine coverage which is 60% is unlikely to control an epidemic disease such as brucellosis.

In this study, older animals were more likely to be seropositive than younger animals (OR =1.7, 95%CI: 1.4 -2.2). In the current study, a higher seroprevalence has been found in animals originating from the three districts of Aqrah, Zakho and Simele than in Dohuk, Amadiya and Shekhan, the highest seropositivity of the animals has been found in the Aqrah district (54.1% of the animals positive). This may be largely due to the main road passing through the district used for the illegal movement of animals.

Flock size has been also found to be associated with brucellosis seropositivity; and larger flock might be suspected to be related with intensive management practices, which are typically more difficult to control and allow for closer between animals and their environment. It increases the potential exposure to infectious excretions, which favour the easy spread of the disease among animals (Coelho et al., 2007; Solorio-Rivera et al., 2007; Coelho et al., 2008). The odds of Brucella seropositivity in small ruminants was 2.2 higher (95% CI: 1.2; 4.3) for animals originating from farms with a history of goat abortion in the preceding 12 months. Abortions play an essential role in the spread of brucellosis due to contamination of the environment and subsequent ingestion of pasture contaminated with Brucella bacteria (Alton, 1982). The survival of Brucella to subsist outside mammalian hosts is relatively persistent as compared to other non-sporulating pathogenic bacteria in similar circumstances (Garin-Bastuji, 1993). Therefore, the cohort study aims to investigate more about different aspects of brucellosis, including study seroconvert and abortion forms of Brucella infection in animals, selected for the cohort study. The odds of Brucella seropositivity in flocks, where sheep and goats grazed together was 2.0 times higher (95% CI: 1.08; 3.9) as compared to flocks, where sheep and goats grazed separately. Considering the contagious nature of Brucella species, sharing gazing and drinking water between sheep and goats facilitate the transmission of the disease (Reviriego et al., 2000). Aune et al. (2012) found that, Brucella could persist on soil or vegetation and foetal tissue for 21-81 days, depending on the month, temperature, and exposure to sunlight. Environmental contamination caused by an aborted foetus, birth tissue, faeces, or vaginal fluids can persist on soil, and vegetation might transmit the bacteria to female sheep and goats graze, these pastures during the pregnancy period, and causes seroconvert of serological results.

The amount of money spent on animal health, was shown to reduce the seroprevalence to brucellosis (Chapter 4), and this agreed with results of other researchers and they found that, lack of money to pay for livestock health services play a significant effect on the increase of the brucellosis infection (Mwinyi, 2017).

Seropositivity and risk factors of Toxoplasma gondii

Toxoplasmosis is also considered a significant health problem in sheep and goats resulting in economic losses for producers (Hill & Dubey, 2013). Improving the awareness of farmers about the ways of transmission and prevention of infection with toxoplasmosis should be increased via education. Further study should be conducted to explore the effects of disease on food animal production (Tilahun et al., 2018; Henneb et al., 2019).

In general, T. gondii infection is common and widespread in small ruminants of the study area. The prevalence of infection in small ruminants indicates the potential transmission to humans, when people consume products ( undercooked meat) from these animals (Gazzonis et al., 2015).

In this study (Chapter 5), the present of cats on the farm increases the seropositivity of T. gondii in sheep and goats flocks (OR= 6.3, 95%CI 1.6 –24.6), and it is in agreement with another study (Zhang et al., 2016a). The consumption of feed and pasture contaminated with oocysts of affected cats is considered the principal method of infection for sheep and goats (Dubey, 1998c); however congenital infection is also possible (Chiebao et al., 2019). In contrast to other studies, they found that, the presence of cats is not a risk factor for increasing seropositivity of T. gondii in infection in small ruminants (Tzanidakis et al., 2012; Dahmane et al., 2020).

In the current study, goats had higher seropositivity than sheep, even though they were sampled in the same region and often in the same flock. These findings agree with another study (Anastasia et al., 2013) that hypothesised that, goats were more susceptible to infection with T. gondii than sheep due to differences in their immune systems. However, it is possible that, these differences are not indicative of true species differences but may be associated with management practices, implemented for the two species. However, the co-grazing of sheep and goats and the similar management in mixed flocks should result in similar seroprevalences. Furthermore, given the browsing nature of goats, it could be expected that, goats would have a lower seroprevalence to Toxoplasma than sheep (Rahman et al., 2014). These findings further support the belief that, there are differences in susceptibility to Toxoplasma between sheep and goats, potentially associated with different immunological responses to infection. While in another study, they found the highest T. gondii seroprevalence in sheep than goats (Gazzonis et al., 2015).

The results presented in Chapter 5 support the belief that, T. gondii is endemic in Dohuk province, with infection widely distributed in sheep and goats. Toxoplasma gondii and Neospora caninum are two closely related obligatory apicomplexan parasites associated with reproductive disorder in small ruminants, causing embryonic reabsorption, mummification, abortion, stillbirth and neonatal losses, causing economic losses in small ruminants production (Dubey, 2009b; Reichel et al., 2013; Villagra-Blanco et al., 2019). The results presented in Chapter 6 support the belief that, T. gondii is endemic in Dohuk province, with infection widely distributed in sheep and goats

Seroconversion to Brucella melitensis and Toxoplasma gondii during pregnancy and its association with loss of pregnancy in small ruminants in Dohuk Province, Iraq

Reproductive failure has a negative impact on animal production, health and welfare and ultimately rural economies (Gebremedhin et al., 2013). Although brucellosis and toxoplasmosis are reported to have detrimental effects on pregnancy outcomes in the Middle East as well as being potential zoonotic diseases (Ortega-Mora, 2007; Smith & Sherman, 2009a). Most studies are investigating the diseases that have relied upon cross-sectional studies. The results of such studies can be questioned, especially with respect to causation and temporal events. Prior to the study outlined in Chapter 6, the influence of seroconversion on the reproductive outcome of sheep and goats had not been investigated through the use of prospective studies in Iraq. Although prospective or cohort studies are time consuming and costly, they offer the significant advantage that more confidence is obtained on the validity of disease outcome (Grimes & Schulz, 2002).

Small ruminants that seroconverted to Brucella during the two-month prospective study were 2.9 times to lose their pregnancy than animals that did not seroconvert. Mailybayeva et al. (2017) revealed that, the presence of erythritol in the placenta has been identified as an important growth factor for Brucella (Petersen et al., 2013); therefore, it is not surprising that, pregnant sheep and goats which are carriers of Brucella would seroconvert during their pregnancy.

The results highlighting the increased risk of loss of pregnancy in animals which seroconverted agrees with another study that found experimental infection with B. pinnipedialis at mid-gestation of cattle also resulted in seroconverted with serological results (Rhyan et al., 2001). Abortions arising from brucellosis in sheep and goats predominantly occur during the last six weeks of gestation, not only resulting in progeny but loss of lactation resulting in a further loss for producers. In order to diagnosis the aetiology of abortion events/storms in sheep and goats, samples are required from multiple cases and multiple sites, including the aborted foetuses, placentas, and sera from the dam, so the causes of abortion can be diagnosed (Rowe, 2019).

In the current study, only 37.5 % of abortions were associated with seroconversion to Brucella or Toxoplasma indicating that potentially other infectious or non-infectious factors are associated with abortions in small ruminants in Iraq. Further studies need to be undertaken needed to identify these causes in Dohuk province and should involve a more thorough sampling protocol of aborted material and from ewes and does that abort. The effect of toxoplasmosis in pregnancy sheep and goats for the seroconvert and losses of the pregnancy are very low than brucellosis, as the number of the infected cats in this province very low (Razzak et al., 2005).

Economic assessment

Brucellosis caused by brucellosis is an infectious zoonotic disease with reportedly significant economic impacts on both the livestock industry and public health (Rossetti et al., 2017). Although the economic effect of brucellosis in small ruminants has been evaluated in other countries (Montiel et al., 2015; Singh et al., 2015), a lack of available data in Iraq has previously evaluated economic losses from this disease challenging. Using data, sourced from the cross-sectional and longitudinal studies conducted as part of the research reported in this thesis and from local and regional studies, it was possible to investigate the economic impact of brucellosis through pregnancy losses, reduction of milk yield and perinatal mortality in sheep and goats in Iraq. This study found that the annual financial loss was decreased at approximately US$ 1.75 to 0.55 US$ per head, using a seroprevalence in small ruminants of Dohuk of 31.7% (95% CI: 26.1, 36.3) (Chapter four) and (Al Hamada et al., 2017). In this study, the proposed control programme for brucellosis in small ruminants in Dohuk Province has been estimated to cost US$ 3.24 million ($ 2.97-3.51 million) over all the 20 years period. This study found that the mass vaccination programme proposed (vaccinating all females and entire males older than three months of age) was financially viable (positive NPV and BCR > 1). Others have also reported the financial benefit of controlling brucellosis by implementing a vaccination programme in small ruminants (Singh et al., 2018b). Control of brucellosis in livestock also benefits humans by reducing infections (Singh et al., 2018a). From our study, mass vaccination has been shown to decrease the seroprevalence in small ruminants from 31.7% to 6.66% after 20 years of implementing of the proposed mass vaccination programme. This highlights the benefit of implementing a mass vaccination programme (with e.g. Rev. 1) for reducing the prevalence of brucellosis in Iraq.

The sensitivity analysis in this study indicated that the abortion rate followed by losses from abortion has the largest effects on the outcome. In another similar study conducted in Kurdistan, Iraq by Alshwany (2019), the abortion rate also had the largest effect on a cost-benefit analysis; however in that study, the average price of lambs or kids had the second-highest effect on the outcome. These studies highlight that; reduction in the abortion rate would be expected to have a major impact on the economic benefit arising from disease control. Generally, higher seroprevalence results in greater losses in productivity with seropositive animals having increased rates of abortions, perinatal mortality and infertility, also reduce milk yields and growth (McDermott et al., 2013). In the Iraqi Kurdistan Region study found that the prevalence of brucellosis in small ruminants were 4.9% in 2015 and economic losses were approximately US$ 6.14 Million (Alshwany, 2019). Control of brucellosis in animals varies between countries, which results in different impact of the disease on profitability (Godfroid et al., 2011). In Nigeria, the annual economic losses caused by brucellosis in small ruminants were US $ 3.2 million (Brisibe et al., 1996). In Peninsula Malaysia with the US $ 2.56 million for caprine brucellosis (Bamaiyi et al., 2015). Since treatment of infected animals is not attempted due to the intracellular localization of Brucella and it is ability to adapt the environmental conditions encountered in the macrophage host cell (Köhler et al., 2002). The manual sensitivity analysis, not surprisingly, demonstrated that, improving the protection rate of the vaccine would results in a better economic performance of the vaccination control programme. Similar results have been reported in other studies (Alshwany, 2019).

Limitations of the present study

With most research studies, there are potential limitations with the current study. Restricting the ability to measure the effect of brucellosis accurately is the scarcity of data on the livestock productivity losses attributable to the disease, such as milk production, period of milking, and amount of milk per season. Either the use of values for parameters taken from other countries or from expert opinions may over or under-estimate values for Iraq. These could result in spurious findings in the economic analysis (Chapter 7). Although the questionnaires used in the current study (Chapters 4 to 6) played an essential role in identifying the risk factors of brucellosis and it is economic impact, several factors may have potentially affected the results of the economic study for brucellosis. Firstly, the current government policy is to support farmers through the supply of animal feed at a discounted price; however, the amount provided is determined by the farmer’s flock size. Consequently, some farmers may have overstated the number of livestock owned to gain extra benefits. Secondly, reluctant interviewees, this is a limitation of the study and results in bias – having an official present during the questionnaire in the study resulting in over or underestimating economic losses and providing dubious associations between factors and seropositivity.

Usually, brucellosis is diagnosed by serological assays; however no test is 100% accurate (sensitive or specific) (Nielsen & Yu, 2010). In chapter, four, two tests were utilised. For brucellosis, all samples were tested with the RBT and iELISA and the results interpreted in parallel in Chapter 4 (animals were classified as seropositive if at least one of the serological assays was positive). The iELISA depends on the detecting of antibodies in the serum of infected or vaccinated animals (Hobbs, 1985). For the RBT, the agglutination intensity is affected by many factors, including the amount of antigen, the temperature at which the test is run, the duration between adding the antigen and reading (interpreting the result), the experience and visual acuity of the test interpreter and potential cross-reactions with LPS of other bacteria (Cho et al., 2010). In the current study, isolating (culturing) and identifying the infecting Brucella species was not undertaken because of time and funding constraints.

For toxoplasmosis (Chapter Five), serological tests to detect antibody to T. gondii for diagnosis. In the present study, tested for anti-T.gondii IgG antibodies by using two commercial serological tests (iELISA and LAT) has been represented. The latex test detects IgG1, and IgM produced during acute cases of toxoplasmosis while the iELISA detects IgG, which is the dominant immunoglobulin in chronic cases (Jiang et al., 2008; Györke et al., 2011). There are many serological tests to detect antibodies in the blood produced in response to an infection and depending on the type of antibodies present (IgG or IgM) work together to produce short term and long-term protection against infection. The immune system IgM titre peaked three weeks after infection and IgG titres exceeded IgM titres at a mean time of 4.7 weeks after infection (Trees et al., 1989); a current or past infection can be determined, such as LAT, ELISAs and IFA. A combination of serologic tests (LAT and iELISA) is usually required to establish whether an individual has been most likely infected in the distant past or has been recently infected. In order to better understand the epidemiology of toxoplasmosis in sheep and goats, by using more accurate tests such as PCR and better protect small ruminants from toxoplasmosis, it is necessary to validate the commonly used serological tests in this species.

Recommendations

Control measures for a disease should be designed based on the epidemiological features of the disease of interest in the specific locality, as it is rare that, one programme can be universally adopted in all the areas or countries (Robertson, 2020). The development and implementation of a programme must be appropriate for the specific country, region or area. Firstly, it is important to specify whether the goal of the programme is the control or eradication of the disease and this mainly depends upon the financial situation within the country and the economic impact of the disease. Secondly, it is critical to have accurate information about the factors associated with the disease (Al-Rawahi, 2015). These factors include the location and environment, where the disease is distributed, the animal population and the management and husbandry practices adopted, the expected prevalence, the culture of the owners and their willingness to cooperate in a control programme. Once the epidemiological information of the disease is known, the country may adopt a specific strategy or a combination of strategies to control the disease (Seleem et al., 2010; Senein & Abdelgadir, 2012; Chen et al., 2016).

Many Brucella-free countries have policies in case there is the introduction of disease by implementing strict border control, quarantine and slaughtering policies against infected and in-contact susceptible animals, as well as imposing strong restrictions on the movement of animals and vehicles from and around potentially infected premises. After slaughter, the carcasses are either burnt or buried in the infected premises, and the building thoroughly washed and disinfected, movement restrictions applied and the affected farms quarantined. Test and slaughter programme could be adopted in situations, where the prevalence is less than 5% and surveillance and laboratory have excellent facilities (Zamri-Saad & Kamarudin, 2016). However, a test and slaughter programme is not suitable, when there is a high prevalence or in countries that have limited financial resources. Therefore, a confirmation process using more accurate methods such as PCR for aborted material and isolation Brucella by agriculture and different controlling methods has been adopted in many countries (Nielsen & Yu, 2010).

Some farms are at high risk of infection with Brucella spp. through adopting the practices such as co-grazing of sheep and goats where small ruminant’s flocks that co-grazed were 2.0 times more likely to be positive for brucellosis than those that grazed separately (Chapter 4). Education is a key aspect of disease control (Tilahun et al., 2018). In the current situation, it is recommended that, educational material is developed and administered to producers focusing on the need for improved biosecurity and ensuring that animals are tested for brucellosis prior to introduction into their flocks. All purchased animals should undergo a quarantine period for one month prior to mixing with the existing flock to minimise the likelihood of transmission of brucellosis (Giasuddin et al., 2018). If purchased animals are pregnant, they should be isolated from the flock until they have given birth. It is recommended that, the importation of ruminants into Dohuk province be restricted to animals that are seronegative and have originated only from brucellosis-free flocks. Implementing and enforcing such importation protocols or completely banning of importation of small ruminants from neighbour countries or provinces would be prudent to reduce the risk of introducing new biotypes of Brucella or reintroducing infection to a brucellosis-free flock. Mass conjunctival vaccination of sheep and goats with test and slaughter programme, in addition to the adoption of improved hygiene and biosecurity practices such as flocks health management, environmental management, farm management, and animal welfare, is recommended as a control strategy in Dohuk. Ideally, the Kurdistan government should be more involved in the control of brucellosis in small ruminants. It should consider paying a premium for milk from brucellosis-free flocks to minimise the public health impact of the disease. In order to increase awareness and encourage the adoption of better health behaviours, the government should conduct the public education programmes related to the disease in schools and communicates in rural areas. Information should be provided on the clinical signs, transmission routes and preventive and control measures for the disease. The educational message may be provided through various routes, including television, radio, warning signs, post and newspapers (Chen et al., 2016). Farmers should also seek veterinary advice on the brucellosis status of their animals by testing their animals. Furthermore, as brucellosis reduces flock productivity through decreased production of milk, there is a financial benefit of producers being involved in a certified-free flock system. Moreover, apply penalties for the infected flock, so it is produce driven by restrict movement of animals from infected flocks, only move to slaughter /abattoirs, not sale milk for fresh, and manufacturing milk that requires pasteurisation, the government should conduct an annual public education programme on the brucellosis and toxoplasmosis in schools and communities in rural area. An educational campaign for the public could be conducted through advertisements advising of certified free flocks providing fresh milk, avoiding unpasteurized milk products can be effective, and awareness programme and health education, especially for the rural population by utilizing a wide variety of media technologies, and education of all personnel involved are essential. There is also a need to improve the diagnostic capacity of both veterinary and district hospital laboratories by a confirmatory process by using more accurate tests and different controlling method. Capacity building and training for improving the quality of the veterinary services and appropriate diagnostic laboratories on the basis of adopted standards of the International Organization for Animal Health (OIE), including standardization and quality control of diagnostic kits or reagents and vaccines, are necessary.

Elimination of communal flock management by preventing co grazing with other flocks and implementation of strict animal movement control will assist in the eradication of B. melitensis in small ruminants flock in Dohuk. It province by applying a strong control system such as using flock numbers this meaning the flock is registered as a standard flock in Dohuk province and should follow the biosecurity role of the province. Subsequently a policy of tests and slaughter of all infected animals could then be adopted in Dohuk province.

In developing areas such as Dohuk province, the implementation of effective test-and-slaughter policies is hindered by a lack of financial resources to compensate farmers whose animals are slaughtered (McDermott & Arimi, 2002; Godfroid et al., 2011). Test-and-slaughter policies can also paradoxically contribute to the spread of infection when identified seropositive animals are sold instead of being slaughtered (Renukaradhya et al., 2002). Therefore, after slaughter positive animals the carcasses should burnt or buried on the infected premises and put the affected farms under quarantined. Consequently, vaccination is considered the best way to initially control the disease in the region as the vaccine, Rev-1, is efficacious in adults, as well as animals 3 to 6 months of age, and induces a high and durable immune response (Alton & Elberg, 1967; Blasco, 1997). However, surprisingly the seroprevalence in the current study was still high (31.7%) even though the kids and lambs are vaccinated by the conjunctival route, when they are between 3 and 6 months of age. This high seroprevalence is unlikely to associate with false-positive reactions arising from the vaccination (Saxena et al., 2018). However, it could be due to a low vaccine efficacy associated with inappropriate storage and transport of the vaccine in and to the field (poor cold chain) (Kornspan et al., 2019). It is important to follow the instructions shared by the vaccine manufacturers and provide formal training of the vaccinators by experienced veterinarians working for the Kurdistan government. The cost- benefit analysis outlined in Chapter 5 revealed that, vaccination of all entire animals over the age of three months was a viable method to reduce the prevalence of the disease over time and it is recommended that such a mass vaccination programme be implemented throughout the Kurdistan region. Control illegal movement of animals between Iraq and other neighbour countries with mass vaccination may have on the brucellosis control programme and potentially would reduce brucellosis in small ruminants. All imported animals need to have a certification that, they have been vaccinated, along with a negative test and be sourced from certified flocks free from disease.

Development and implementation of appropriate veterinary legislation and animal’s health policies, as well as the adoption of appropriate control and eradication programmes are essential

Compulsory vaccination of all young female lamb/kids between 3 -6 months, and vaccination other adult female at least six months before starting the breeding season with Rev .1 through the conjunctiva, this lead to reduce the prevalence of brucellosis. Compulsory tagging all animals were introduced. Each property was allocated a property identification colour. Allowing individuals to be traced back to their property of origin. It was a legal requirement that all animals were identified by different tags before sale or inspection at abattoirs. Trace back and trace forward of test positive sheep or goats were the integral part to the success of disease checking.

Milk ring test was selected for long term surveillance of brucellosis in sheep and goats flocks. Each distract or state in Iraq should conduct milk ring tests on each sheep and goats flock at least three times a year throughout the eradication phase, and for five years after becoming brucellosis free.

All infected flocks should be tested at six months’ intervals and all positive animals should be removed for slaughter. The abattoir also should be under monitoring each mature breeding sheep and goats that were sent to abattoirs for slaughter were sampled and tested. All cases of abortion are reported to authorities and it has been investigated to dismiss the possibility of brucellosis infection.

The incidence of abortion was very low in Dohuk Province, and the aim of this thesis to estimate the prevalence of the T. gondii antibodies in small ruminants as toxoplasmosis considered as one of the major causes of infectious reproductive failure of sheep and goats in many countries.

Prevention of the spread of toxoplasmosis through strengthening farm biosecurity measures is essential. It is recommended that to prevent infection in small ruminants, cats should be vaccinated by zona pellucida ( ZP) and this vaccine causes a tendency towards an increased incidence of unsuccessful mating or pregnancy (Eade, 2007). Control and prophylactic measures must be adopted to improve the rearing system and the implementation of health promoting programmes in a joint effort between sheep and goats farmers, farmers associations and veterinarians to inform about the means of transmission of the infection and for a better understanding of toxoplasmosis. These programmes should cover methods of disposal of foetal membranes and aborted lambs/kids through deep burial or burning (Al Hamada et al., 2019). Measures to prevent infection of food animals include keeping the animals indoors; keeping cats away from farms, feed, and bedding production and storage; providing clean drinking water and blocking access to surface water; implementing strict rodent control. In addition, control strategies for the stray cat population must be implemented.

The methodology adopted in the current study should be repeated in a larger population of small ruminants in Dohuk to confirm the findings of the current study and to establish the impact of toxoplasmosis and brucellosis on the reproduction and productivity of sheep and goats in Dohuk province.

Adopting a one-health approach is recommended where the veterinary and medical professionals work together to minimise the impacts of toxoplasmosis and brucellosis on the human and livestock populations. However, for such studies to succeed a better veterinary services unit including infrastructure and expertise is required in the province.

Future research

Isolation of Brucella is the gold standard in the laboratory diagnosis of brucellosis. It is necessary to determine the serotypes and species circulating in Dohuk province is a worthwhile investment to provide the basis for the designing and implementation of control strategies in this area. Bacteriology is being accepted for brucellosis diagnosis for many reasons such as time consuming, insensitive, previous antibiotic, because of bacteriological culture for Brucella was not performed in many provinces in Iraq; other tests are used to diagnosis brucellosis. Also Brucella cannot be culture from patient’s samples. In Italy, analysis of field circulating strain of Brucella explores more knowledge on the epidemiology of brucellosis. It is also useful for formulating the policies and strategies for the control and eradication of the brucellosis in animal population, as there is inferred evidence of the predominance of B. melitensis and other types of brucellosis such as B. abortus , B. canis, and B. ovice etc. (De Massis et al., 2019). Therefore, use blood culture to identify the specific Brucella species circulating in the country (Tekle et al., 2019).

As brucellosis is a transboundary animal disease, information on the current prevalence in different livestock should be shared between neighbouring countries in order to improve the understanding and effectiveness of the regional control of this disease. Several countries in Central Asia are making good progress in reducing brucellosis prevalence in small ruminants by continuous vaccination (Andriy, 2013). In Middle East countries, to protect the investment already made, the neighbouring countries need to enhance control measures within their borders, Regular intercountry veterinary meetings, Regional control of the disease, Accepted and documented movement controls, need to understand all livestock movements both inter and intercountry, Traditional and trade movements.

Brucellosis has been reported in a wide variety of terrestrial wildlife species throughout the world (Godfroid, 2002). Consequently, the risk of transport the brucellosis to small ruminants in Dohuk province will increase. In addition, aborted and parturient material in the environment can also be dispersed by carnivorous animals such as dogs, foxes and wolves (Godfroid, 2002; Simpson et al., 2021), potentially resulting in exposure small ruminants to Brucella (Al-Rawahi, 2014). However, reducing the prevalence of brucellosis in wildlife reservoirs is complicated and costly (Olsen, 2010). Conversely, wildlife species could be a spill over host, infected after exposure to the bacteria from domesticated livestock. In Iraq, wild ruminants, such as wild goats (Capran aegagrus) and Persian fallow deer (Dama dama mesopotamica ), may be presently grazing with domesticated livestock, so implementing a control programme in livestock could minimise transmission to wildlife species and prevent the establishment of a potential wildlife reservoir of infection. In order to understand the role of wildlife species in the spread of brucellosis in Iraq sampling studies should be undertaken of wild species, particularly in regions, where there is a close interface between wild and domesticated ruminants.

Furthered validation of serological assays and molecular characterization studies are required to find phenotypes differences as a way to better understand the biology of the different T. gondii strain may provide further evidence on the public health risk of Toxoplasma from small ruminants in Dohuk province. For better understanding the risk factors associated with T. gondii infection in this region, further studies are necessary to provide detailed information on risk factors associated with infection with T. gondii. These are such as production system, small ruminants welfare, food and water source by using more developed tools including PCR, environmental sampling as an indicator of oocyst contamination and the number of cats (Su et al., 2003; Stelzer et al., 2019). Control of feline carriers remains a challenging problem. Cooking meat to prevent infection, the tissue cysts become non-viable by cooking meat to an internal temperature of 66 ⁰C (Dubey, 2016). Serological tests on blood samples from cats should be performed to diagnosis the seroprevalence of T.gondii in cats from Dohuk province. Analysis of hospital records in order to provide data into seroprevalence rates of selected pathogens that can be utilised to guide screening and diagnostic laboratory testing. Relevant seroprevalence data for endemic pathogens in a given region provide into population susceptibility to acute infection or risk for reactivation disease.

Further studies should be conducted on sheep and goats to investigate other causes of abortion in the Kurdistan region. Although there was evidence that, toxoplasmosis is widespread in this study; there was little effect of seroconversion to the protozoan on the outcome of pregnancy. An expanded comprehensive study is required involving sampling small ruminants from birth to clarify when animals are seroconverting and what impact that has on productivity. Such a study will improve the understanding of the epidemiology and impact of toxoplasmosis on the local animal industry and the potential risk of transmission to humans through consumption of meat or milk from small ruminants (Boughattas, 2017). Also, as toxoplasmosis have zoonotic potential; further studies should include a wide range of hosts such as humans, companion small ruminants and cattle to understand their transmission dynamics in Dohuk province.

Conclusions

In conclusion, the work described in this thesis highlighted that, animals that seroconverted to Brucella were more likely to lose their pregnancy than those that did not seroconvert. In contrast, seroconversion to Toxoplasma did not significantly influence the outcome of pregnancy. Based on the findings of this study, it is recommended that, to control the effect of toxoplasmosis and brucellosis resulting in improved income for local farmers. An integrated approach should be developed and implemented, including mass vaccination for brucellosis, education of the farmers and livestock workers. From the findings presented in this thesis, it was confirmed that, the epidemiology of brucellosis and toxoplasmosis was influenced by several factors, including such as herd size, livestock production type, and interaction with the economy. From the research done in this thesis, indicated that density, herd size, age of animals, reduced veterinary service like vaccination programmes are associated with high Brucella prevalence and the presence of cats, a large flock size, and the method of disposing of aborted foetuses are potential risk factors for Toxoplasma prevalence in sheep and goats.

Continue your journey with our comprehensive guide to Behavior Management and Student Learning Experiences in a School Placement.