LITERATURE REVIEW
1. SOIL – TRANSMITTED HELMINTHIASES (STH)
1.7 Intervention for STH control
The combination of a high prevalence of STHs and poor hygiene and malnutrition is an indicator of a country’s future problem. Therefore, the eradication of STHs worldwide should be given a high priority.153 Three interventions to control morbidity due to STH infections have been recommended by the WHO and these are - regular drug treatment of high-risk groups for reduction of the worm burden overtime; health education; and sanitation supported by personal hygiene aimed at reducing soil contamination.7
1.7.1 Antihelminthic treatment
In areas where infections are intensely transmitted, where there are limited resources for disease control and where there is insufficient funding for sanitation, regular drug treatment should be the main approach for infection control.154 Drug treatment can be by universal treatment in which the treatment can be offered to the entire community, irrespective of age, sex, infection status and any other social characteristics using alternative approaches; the treatment can be targeted at population groups, which may be defined by age, sex or other social characteristics, irrespective of the infection status (targeted treatment); and it can be selective treatment representing individual-level administration of anthelminthic drugs, where selection is based on diagnosis to detect the most heavily-infected people who will be most at risk of serious morbidity and mortality. The selection of the delivery strategy and the frequency of treatment are based on the analysis of available epidemiological data.154
In accordance with the WHO, the recommended drugs for use in public health interventions to control STH infections are: Albendazole (400mg) tablets given in a single dose, reduced to
46 200mg for children between 12 and 24 months; Levamisole (40mg) tablets given in a single dose by weight (2.5mg/kg), though, it has been successfully used at a dose of 80mg in primary school–age children; Mebendazole (500mg) tablets given in a single dose; and Pyrantel pamoate (250mg) tablets given in a single dose by weight (10mg/kg).155
School-based deworming also offers major advantages for untreated children and the whole community by reducing disease transmission in the community as a whole.156
Frequency of regular treatment should vary according to the intensity of transmission and rates of re-infection. These factors must be considered in relation to the resources available and the cost involved in drug purchase and distribution. Different levels of egg output might be obtainable in different parts of the world, therefore, the thresholds proposed by WHO based on the classification of infection as being of light, moderate or heavy intensity are not rigid and should be adjusted for the local situation as reported by WHO 127; also reported in a study in which there is variation between Nigeria and Bangladesh when data on the relationship between the worm burdens of Ascaris lumbricoides and the concentration of eggs in faeces were examined.157
1.7.2 Health education
Health education has proven to be a useful tool in improving the health and increasing hygiene awareness, thus changing health-related behaviour in the population especially when suggested solutions to a health problem are not available or they are too expensive to adopt such as STHs which are related to poverty. Deprived communities understand the importance of the safe disposal of faecal matter and of wearing shoes, but poverty often hinders the construction of latrines and the purchase of shoes. Providing information on the disease and the possible adoption of preventive measures frequently results in an increase in knowledge. 158 Promotion
47 of latrine maintenance and use, washing of hands and proper food handling has benefits that go beyond the control of STH infections.
It is, therefore, reasonable to include health education in all STH-control programs, wherein the health education message can be provided in a simple and inexpensive way as was reported in the review of the global strategy for the control of soil-transmitted helminthiasis, based on regular anthelminthic treatment, health education and improved sanitation standards.154 In Poyang Lake region, China, when targeted health education was given to pupils, adult women and adult men, it was found that, compared with control, the knowledge level among the three kinds of population improved significantly.159
Health education messages can be delivered by teachers in schools, thereby fostering changes in health-related behaviour in children, which in turn involves their parents and guardians.
Educational materials (posters, leaflets, radio and video messages) have been traditionally used to transmit and disseminate health-related messages, though newer methods are being advocated.160
1.7.3 Sanitation and personal hygiene
The transmission of STH infections to humans is by faecally contaminated soil either directly (hand-to-mouth) or indirectly (through food and water). Based on the context of economic development, sanitation is the only definitive intervention that eliminates these infections.154 STH infections are never a public health problem where hygiene and sanitation standards are appropriate. Improvement of sanitation standards always has a repercussion on infection and re- infection level as was the effect of a city-wide sanitation programme on reduction in rate of childhood diarrhoea in northeast Brazil and of Latin America and the Caribbean.161, 162 Mass availability and the type of excreta-disposal facility were the only significant predictors of re-infection in several studies conducted like in Salvador, Brazil suggesting that sewerage and
48 drainage can have a significant effect on STH infections, reducing transmission occurring in the public domain.163
In a study in Ogun state, Nigeria, prevalence of intestinal helminth infection was higher in schools where poor socioeconomic status, poor hygienic habits, and lack of sanitation were present.51 This was also found among school children in Benin City.164 An extensive program of environmental sanitation called “Blue Bay” was conducted in the Brazilian city of Salvador, Bahia, aimed at expanding the city's sanitation network from 26% to 80%. A significant and marked reduction in the rate of childhood diarrhoea and in the prevalence and incidence of geo-helminths infections has already been reported to occur since its introduction.161, 165 Sanitation is inadequate in most cities in developing countries, with major effects on STH infections.166 A systematic review and meta-analysis of 46 studies suggested that water, sanitation, and hygiene interventions as well as their combination, are effective at reducing diarrheal illnesses and STH infections.167
The effect of improved sanitation is slow to development and may take decades to achieve a measurable impact. Often, the high costs involved prevent the provision of sanitation to the communities most in need, and sanitation does not become effective until it covers a high percentage of the population.168,169 For long-term sustainability, environmental health will be required, improving access to safe water and sanitation and improved hygienic behaviour through health education.146