Bovine Fasciolosis In Nigeria Health And Social Care Essay

Tropical fasciolosis caused by Fasciola gigantica is regarded as one of the most important single helminth infection of ruminants in Africa and Asia. As at 1999, with the estimated total cattle population in Africa put at 201 million animals, a loss of about US$840 million from fasciolosis infection was predicted. Liver fluke (fasciolosis) also emerging as a disease that affects humans with about 2.4 million people infected worldwide. Despite the huge economic losses incurred and the widespread distribution of fasciolosis reported across Nigeria, significant control measures have not yet been developed. More rational programs based on epidemiological data for sound control strategies are needed.

This project aims to investigate F. gigantica infection in Kwara state, Nigeria by determining (i) the prevalence of the disease in cattle (ii) the ecological association, population densities and potential for transmission of intermediate snail hosts (iii) the validity of the current diagnostic techniques and (iv) the efficacy of anthelmintics commonly used for treatment in order to provide advice to local stakeholders including farmers and policymakers to improve control of these economically important parasites.

Summary

Liver fluke disease or fasciolosis is a global problem causing losses to livestock of up to US$ 3.2 billion annually. It is also emerging as a major public health problem. According to World Health Organization, an estimated 2.4 million people are infected worldwide. Despite the huge economic losses incurred and the widespread distribution of fasciolosis reported across Nigeria, significant control measures have not yet been developed. More rationale programs based on epidemiological data are needed for sound control strategies.

Molecular studies related to fasciolosis have not also been reported and the majority of studies were based on abattoir and very little research on live animals in Nigeria.

The overall aim of the study is to understand the epidemiology of the disease in Nigeria in order to formulate an improved control strategy. The proposed study would involve cattle prevalence study, ecological studies of the snail intermediate host, molecular identification of snails and their infection status as well as probes evaluated in investigating fluke DNA in faeces.

Background

Tropical fasciolosis is caused by the digenean trematode: Fasciola gigantica. It is regarded as one of the most important single helminth infection of ruminants in Asia and Africa (Boray 1985, Fabiyi 1987). The main intermediate snail host of F.gigantica is super species Lymnaea auricularia senso natalensis: synonym Radix natalensis (Kendall 1965) which is a water-snail . With the estimated total cattle population in Africa put at 201million animals (FAO ), a loss of about US$840 million from fasciolosis infection is predicted (Spithill et al. 1999), this cost is obviously likely to have increased significantly in the last fourteen years. An estimated 2.4million people are infected with fasciolosis worldwide and a further 180 million people at risk of Fasciola infection (Mas-Coma et al. 1999). Although few human cases have been reported in Africa, there have been cases reported in Egypt, Ivory Coast, Madagascar, Mali, Mozambique and Ethiopia (Mas-Coma et al. 1999).

The most recent data reports that Nigeria has a cattle population of about 19.8 million (FAO 2002). They play a very important role in Nigeria, contributing about 12.7% of total agriculture Gross Domestic Product-GDP (CBN 1999). In the tropics, cattle are generally reared under the transhumance husbandry system with little supplementary feeding resulting in low productivity and high pre-weaning mortality (Ulayi et al. 2007).

Despite the huge economic losses incurred and the widespread distribution of fasciolosis reported across Nigeria (Adewole 2010, Nwosu and Srivastava 1993, Schillhorn van Veen et al. 1980, Ulayi et al. 2007), significant control measures have not yet been developed. Knowledge of the epidemiology of infection with F.gigantica has been clouded by the common yet erroneous assumption that it is essentially similar to infection with Fasciola hepatica because of the similarity in life cycle (Spithill et al. 1999). More rationale programs based on epidemiological data for sound control strategies are required.

Most research in Nigeria has been carried out in abattoirs to determine the burden of the disease, at present to my knowledge there are no records of studies on live cattle. These need to take into consideration the management system, life cycle of the parasite as well as modern approaches to control the disease which will include the efficacy of the flukicide treatment.

Molecular studies have been carried out extensively on F. hepatica both in the characterization of the parasite as well as parasite detection in the intermediate snail hosts, but such studies on F. gigantica are lacking in Nigeria. Recently, a commercially available ELISA-based copro-antigen test as well as polymerase chain reaction(PCR) technique has shown the potential for detecting pre-patent infection (Martínez-Pérez et al. 2012, Mezo et al. 2004). These techniques have not yet been validated for F.gigantica in Nigeria.

Aims of the Project

This project aims to investigate F. gigantica infection in Kwara state, Nigeria by determining (i) the prevalence in cattle (ii) the ecological association, population densities and potential for transmission of intermediate snail hosts (iii) the validity of the current diagnostic techniques and (iv) the efficacy of anthelmintics used for treatment in order to provide advice to local stakeholders including farmers and policymakers to improve control of these economically important parasites.

Nigeria showing Kwara.bmp

Figure : Map of Nigeria Showing Kwara State

Methodology

Study Area

The study would be carried out in Kwara state, Nigeria located between latitude 8⁰ 05' - 10⁰ 15' N and longitude 2⁰ 73'- 6⁰ 13' E. It has a total landmass of about 34, 500 square kilometer comprising rainforest in the south and wooded savannah in the larger part of the state. It has a summer rainfall with an annual range of 1000mm- 1500mm and average maximum temperature varying between 30⁰C and 35⁰C (Kwara State 2012).

Study Design

Sample size would be calculated (Thrusfield 2007) using the values 22.7% as expected prevalence based on a previous study carried out in Kwara state (Adewole 2010), 95% confidence interval and ±5% desired absolute precision.

A systematic grid sampling approach with a grid quadrant of 10km by 10km overlaid on the state map (Figure 2) would be used. The coordinates of the intersects would be identified, random points selected using the Geographic information system software and cattle in areas closest to the intersect would be sampled. Equal number of animals would be sampled in each grid to get the same level of precision of the prevalence estimate. Handheld GPS device would be used to identify the areas. Areas with no cattle population would be recorded to give a geographical spread of the cattle in the state.

In each area to be studied, specific farms would be randomly selected by the Veterinarians working in the study areas.

kwara grid map labelled with LGAs.bmp

Figure : Grid Map of Kwara State Showing the LGAs

Cross-sectional Prevalence Study

Questionnaires on household and epidemiological characteristics as well as anthelmintic usage would be administered at interview to each of the cattle farmer in the study.

A maximum of 10 cattle per herdsman would be sampled in order to avoid bias due to multiple animals from the same herd. The information to be recorded for each cow are: age, sex, breed, body condition score of 9 according (Nicholson and Butterworth 1986), anaemia status using the FAMACHA© ocular mucous membrane examination system (van Wyk and Bath 2002) and Hemocue™ for reference measurement of peripheral blood haemoglobin.

Faecal samples would be obtained directly from the rectum in a disposable plastic gloves or from the ground if seen being produced, the glove would be turned inside out, carefully tied, labelled and transported under cool conditions to the laboratory. The commercially available kit -Flukefinder©, Richard Dixon ID, US (Malone et al. 1992) would be used to isolate the fluke egg using 2grams of faeces on each individual faecal sample based on the manufacturer's instruction. Methylene blue would be added for contrast and then examined under the x20 magnification stereo-microscope. Eggs would be identified using standard keys (Soulsby 1982)

The second part of the faeces would be stored in 80% alcohol until subjected to further molecular analysis.

Malacological Study

A selection of aquatic habitat within the study area would be examined for freshwater snails with the altitude the location geo-referenced. A 15 minutes snail search on each site using a snail scoop would be carried out. A knee length boot and rubber gloves would be used as protective clothing to avoid infection with Schistosomiasis. The type of water body, proportion of shade and degree of pollution observed would be recorded. Water chemistry parameters: temperature, conductivity as well as pH would be measured in each of the habitats.

Snails would be identified morphologically based on field guide provided by the Danish Bilharziasis laboratory (Brown and Kristensen 1993). Only snails identified as Radix species would be considered and counted and recorded. They will be screened for trematode infection by stimulating for cercarial shedding using strong artificial light for 6 hours in a 10ml glass beaker. The digenean larvae would be identified under the dissecting microscope. A few representative of the snail from each site would be washed in distilled water and stored in 80% ethanol until DNA extraction for further molecular analysis.

Chemotherapeutic Efficacy Studies

Naturally infected animals positive for Fasciola eggs would be recruited into the study. Animals would be randomly distributed by faecal egg counts into control and treatment groups according to the method described by Coles et al 1992. Briefly described, 5grams of faeces would be collected from the rectum of each animal for egg counts. Animals would then be treated with an anthelmintics (albendazole, clorsulon and triclabendazole) according to manufacturer's recommended dose based on the weight of the animal. Data on age, sex and breed would also be recorded for each animal in the study. Faecal samples would then be collected every 2 weeks after treatment. The faeces per herd would be pooled and divided into 2 parts. Half of the faeces would be subjected to sedimentation techniques using mesh sieves and faecal egg count carried out. The remaining half of the faeces would be stored in 80% alcohol until subjected to further analysis using PCR techniques to monitor the efficacy of the drugs.

Molecular Analysis

Polymerase Chain Reaction in Snails

A representative of snails from each site washed in distilled water and stored in 80% alcohol would be subjected to further analysis

Genomic DNA would be extracted from the foot tissue of three snails from each water body using commercially available kit. Molecular identification would be performed using polymerase chain reaction (PCR) using species specific primers (Ai et al. 2010, Kaplan et al. 1995, Velusamy et al. 2004) with the aim of confirming the diversity of snails in the study site. They would also be screened for infection with Fasciola spp.

Spatial Epidemiology of Bovine Fasciolosis using Geographic Information System

Geographic information system (GIS) on Kwara state would be constructed using the administrative boundaries as bases. Potential snail habitat would be overlayed onto the GIS map. Prevalence of Fasciola spp would be related to the presence of water bodies which represent a favourable environment for the intermediate host.

Pilot Testing

Questionnaires would be tested within a population similar to the target population.

Ethical Consideration

Ethical approval would be sought from the Kwara state Ministry of Agriculture and informed consent duly obtained from the herdsmen.

Statistical Analysis

Data from the questionnaires would be entered into Excel before analysis using the SPSS software (version 19). Information from the questionnaire would help to understand the management risk factors that may predispose to infection. Faecal egg and snail count would be log transformed and included as covariates in the statistical analysis using general linear models (GLM). The effect of factors such as the cattle data (age, sex, breed), the geographical and epidemiological information obtained would be investigated for association.

The relationship between body condition score(BCS) and FAMACHA© system would be assessed for effectiveness in strategic anthelmintic therapy as well as their ability for identifying clinical fluke infection.

Data Management and Data Sharing

The findings of the project would be presented at workshops and conferences, feedback would be provide to the farmers as well as policy makers, as well as publication in scientific journals.

Contingency Plan

Timetable and Milestones

DATE

Oct 2012-Mar 2013

Apr2013-Sep2013

Oct2013-Mar2014

Apr2014-Sept2014

Oct2014-Mar2015

Apr2015-Oct2015

Literature Review & Study Design

 

 

 

 

 

 

Field Studies in Nigeria

 

 

 

 

 

 

Laboratory Analyses

 

 

 

 

 

 

Statistical Analysis

 

 

 

 

 

 

Writing Up of Theses