Epidemiological Studies of Schistosomiasis in Jos South Local Government Area, Plateau State, Nigeria

Epidemiological Studies of Schistosomiasis in Jos South Local Government Area, Plateau State, Nigeria

Chapter One

AIM AND OBJECTIVES

The streams surveyed in the study area harboured the snail hosts of schistosomes and most of the inhabitants of the area dispose their urine and stool indiscriminately on the environment including the vicinities of the water bodies. Children, farmers and some other inhabitants visit the streams for one water contact activity or the other. These epidemiological factors were supposed to bring about increase in the prevalence of the disease in the Local Government Area, but the reverse was the case as reported in patients who attended surrounding hospitals and clinics.

Content Summary

Aim

To determine the true picture of the disease – schistosomiasis in the Local Government Area and the factors contributing to its spread.

Specific Objectives

To determine the prevalence of schistosomiasis in the
To assess the relationship between physico-chemical factors and occurrence and distribution of snail intermediate hosts of
To determine some factors influencing the transmission and spread of schistosomiasis in the study
To assess the effect of water contact activities on the infection rate of schistosomiasis.

CHAPTER TWO

LITERATURE REVIEW

DISTRIBUTION OF SCHISTOSOMIASIS

Schistosomiasis is widely distributed in the world. The areas affected are the Americas (Brazil, Venezuela and Suriname as well as several Caribbean Islands),the Eastern Mediterranean (Islamic Republic of Iran, Iraq, Saudi Arabia, Syrian Arab Republic and Yemen), Eastern Asia (Cambodia, China, Indonesia, Japan, People’s Democratic Republic of China, the Philippines) and some parts of Africa. Like many other parasitic helminths, the distribution and intensity of schistosome infections are variable by locality. This is particularly true with this parasite, mainly due to the strictly limited ecological conditions for habitats of vector snails and conditions of habitats in relation to annual rainfalls, unexpected drought, irrigation projects and industrial activities (Kaneko, Esiaku, Yoshikazu, Hiroshi, Okoronkwo, and Toshiyuki,1991). Schistosoma haematobium is found in 53 countries in the Middle East and Africa including the Island of Madagascar and Mauritius. There is also an ill-defined focus of S. haematobium in India. Intestinal schistosomiasis is found in 45 countries including the Arabian Peninsula, Egypt, Sudan, Sub-Saharan Africa, Brazil, some Caribbean Islands, Suriname and Venezuela. S. intercalatum has been reported from ten countries within the rain forest belt of Central Africa. Two geographically isolated strains of Schistosoma intercalatum are recognised, the lower Guinea strain and the Congo strain which differ from each other in a number of characteristics (Jourdane et al., 2001). S. japonicum is endemic in China, Indonesia and the Phillipines and has been reported in Thailand. S. mekongi is found in Cambodia and Laos along the Mekong River (WHO, 1984).

The global distribution of schistosomiasis has changed significantly in the past 50 years, with control successes achieved in Asia, the Americas, North Africa and Middle East. Schistosomiasis has been eradicated from Japan, transmission has been stopped in Tunisia and very low in Morocco, the Philippines, Saudi Arabia and Venezuela (WHO, 1984). However, environmental changes linked to water resources development, increasing population and population migrations has led to the introduction and spread of the disease to previously low or non-endemic areas, particularly sub-Saharan Africa. The building of the Diama dam on the Senegal River has introduced intestinal schistosomiasis to both Mauritania and Senegal. Refugee movements, and population displacement in the horn of Africa have also introduced intestinal schistosomiasis to Somalia and recently to Djibouti. Despite the progress in control, the disease still remains endemic in 76 developing countries putting more than 600 million people at risk of infection. Over 200 million people are currently estimated to be infected. It is estimated that more than 80% of all these people infected by schistosomiasis live in Sub-Saharan Africa (WHO, 1984).

There are a number of less important species of schistosomes infecting man.

intercalatum is endemic in parts of Zaire, Gabon, Cameroon, with small foci in Central African Republic, Chad, Nigeria, Upper Volta (WHO, 1984).
malayensis was recently reported in Malaysia. In addition, a number of animal species accidentally infect man to cause zoonotic infections. These include S. bovis infecting cattle, sheep, and goats in Africa, parts of Southern Europe, and Middle East; S. matthei infecting cattle, sheep and goats in Central and Southern Africa; S. margrebowiei infecting antelope, buffalo, and water buck in Southern and Central Africa; S. curassoni infecting domestic ruminants in West Africa and S. rodhaini infecting rodents and carnivores in parts of Africa (WHO, 1984).

SCHISTOSOMIASIS IN NIGERIA

Several isolated studies on the prevalence of the disease in Nigeria have been reported following the extensive survey of the former Northern Nigeria by Ramsey in 1935. According to the legend Blair, (1956), the Fulani tribe of Northern Nigeria brought schistosomiasis with them during their migration from the Upper Nile Basin. The disease, therefore has a long history in Nigeria. It is essentially an infection of rural agricultural communities where rural lifestyle and behaviour encourage the contamination of inland water with human excreta and urine. Until recently, schistosomiasis was not considered a public health problem in Nigeria for two reasons. Firstly, schistosomiasis was restricted to rural communities where hygiene is inadequate, where poverty prevails, where malnutrition and infection with other parasites are common (Coutinbo, Ferreira, Feitas,Silva, Caralcanti and Samica, 1992). Secondly, it is a disease common to school aged children in whom the disease remains silent or mildly asymptomatic for many years. To this end, most previous studies on schistosomiasis in Nigeria were concentrated in rural areas (Arinola, 1995).

CHAPTER THREE

MATERIALS AND METHODS

THE STUDY AREA

According to Plateau State Ministry of Establishment, Internal Affairs and Information, Jos South Local Government Area (JSLGA) is located south of Jos between longitude 8⁰ 48^’W. and latitude 9⁰ 94^’N., in North Central Geo-political Zone of Nigeria. The headquarters is at Bukuru, which is about 15 kilometres from Jos town, the capital of Plateau State. The area is about 1,250 metres above sea level. With the exception of Obudu, in Cross River State, Jos is the coldest part of Nigeria by virtue of the Plateau. Topographically and climatically the area is very close to Jos. The high land is slightly undulating and rises from the steep escarpments of the riverine plains of the river Benue and descends towards Bauchi State. Located in the middle belt zone of the country, the vegetation is grassland savanna and the landscape is treeless, mostly rocky, with chains of hills and many captivating rock formations. The average minimum and maximum temperatures are 22⁰C (71.6⁰F) and 30⁰C (86⁰F) respectively. Two seasons are distinct, the wet season which lasts from April to October and the dry season from November to March. The wet season is characterised by heavy rains and subsequent flooding of the banks of rivers, streams, ponds and other hydrological resources, while the dry season is characterised by cool, dry, high temperature in February and March. Mean annual rainfall varies from 131.75cm in the southern part of the State to 141.5cm on the plateau.

SAMPLING TECHNIQUES

Participants

The participants were made up of inhabitants in the selected areas in Jos South Local Government Area, Plateau State, Nigeria.

Local Government Council Area Population

The population of the Local Government Area as supplied by the Local Government Council was 160,000 but now 306,716 people of all ages and both sexes.

CHAPTER FOUR RESULTS

SAMPLESCOLLECTED Snails.

A total of 1081 snails were collected from 1999 to 2004

During the dry season in 1999, a total of 611 snails were collected. The snails were made up of 154 Bulinus species, 99 Biomphalaria species and 358 Lymnea species. In the wet season, only 92 snails were collected comprising of 7 Bulinus, 16 Biomphalaria, and 69 Lymnea. A total of 703 snails were collected in 1999 (Table 1).

In the year 2000, a total of 255 snails (196 in dry and 59 in wet season) were collected. The 196 snails collected in dry season were made up of 39 Bulinus, 48 Biomphalaria and 109 Lymnea species. The 59 snails collected in the wet season were made up of 20 Bulinus, 20 Biomphalaria and 19 Lymnea species (Table 1).

In 2001, a total of 87 snails were collected (65 in the dry season and 22 in the wet season). The dry season collections included 16 Bulinus, 13 Biomphalaria, and 36 Lymnea species, while the wet season collections were made up of 5 Bulinus, 2 Biomphalaria and 15 Lymnea species (Table 1).

CHAPTER FIVE

CONCLUSION

As only 21 of 6,377 specimens examined were positive for Schistosoma eggs, the disease had low endemicity in the study area and the snail vectors, though present, were not harbouring the infective stage of the parasite, cercariae.

From this study, it is concluded that the disease, schistosomiasis has a low endemicity in the study area and is actually declining. The null hypothesis is therefore rejected.

SUMMARY OF FINDINGS

Out of the 6,377 samples, made up of 3,190 stool samples and 3,187 urine samples, only 21 samples were positive (0.33%) for schistosomiasis. Out of the 3,190 stool samples, 13(0.41%) were positive for intestinal schistosome, Schistosoma mansoni, while only 8 (0.25%) of the 3,187 urine samples examined were positive for urinary schistosome, Schistosoma haematobium. Of all the age groups examined, the 11-20 years, 21-30 and 31-40 years age groups were more infected (1.75%, 0.57%, 0.62% respectively) compared to the other age groups – younger (1-10 years) and older (41-50 years) and 50 and above each of which recorded 0% prevalence. The age groups, 11-20 years, 21-30 years and 31-40 years are the groups that frequent streams more for one or more water contact activities like swimming, fishing, bathing and playing, than the younger ones, 1-10 years and the older ones, 41-50 years and 50 years and above groups. Males were more infected (0.88%) than the females (0.44%). Males of all ages frequently visit streams for one water contact activity or the other compared with their female counterparts. This study has revealed that water contact has a correlation to the prevalence of schistosomiasis.

None availability of adequate toilet facilities and portable water supply also show correlation to the prevalence of the disease, as those who lack adequate toilet facilities and water supply were more infected (1.56%) compared with those who had the facilities. Students and pupils were more infected (1.00%) than other occupational groups. This group belongs to the 11-30 years age group that were more infected owing to their more contact with water bodies for one activity or the other. They constitute sources of infection.

There was no correlation between water parameters and occurrence and infectivity of the snail intermediate hosts of the disease collected as none of the snail vectors of schistosomes collected was infected. The streams were not infested by the infective stage of the parasites that would have caused the disease, schistosomiasis in the inhabitants of the study area. Of the species of snails encountered, Lymnea was found to be most distributed in the water bodies visited. A total of 1,081 snails were collected out of which 85 (7.86%), were infected, all being Lymnea natalensis and all were collected from one source, Vom/National Institute of Policy and Strategic Studies Kuru stream, while the rest collected during the study were not infected.

SUGGESTION ON AREAS OF FURTHER WORK

The disease, schistosomiasis spreads easily from one locality to another. If an infected person happens to come into an area free of the disease, contaminates any available water body containing snail vector of the parasite, schistosome, with his stool or urine containing the eggs of the parasite, the infective stage, cercariae will develop in the snail vector and eventually emerge into the water. If the definitive host, man enters the stream bare-bodied for any water contact activity, the cercariae will penetrate into the skin initiating infection.

Therefore there is need for similar research to be carried out in neighbouring Local Government Areas and States to ascertain presence of the causative agent of the disease (schistosome) and/or their snail intermediate hosts. If any is detected, efforts should be made to prevent spread by adequately treating the infected individuals and/or eradicating the snail vectors.

CONTRIBUTION TO KNOWLEDGE

From the results obtained, the disease schistosomiasis has low endemicity in the Local Government Area. Also the snail vectors were not harbouring the infective stage, cercariae. Based on my knowledge, the disease, the distribution and infectivity of snail vectors have never been studied in the Local Government Area. So the study has provided base- line data on prevalence of the disease, the distribution and the infectivity of snail vectors in the Local Government Area. Furthermore, the findings are necessary for instituting control measures against the disease. These information will encourage the Local Government to institute measures to avoid spread of the disease into her territory.

RECOMMENDATIONS

Though the disease, schistosomiasis has very low endemicity in the study area as observed from the research, it is recommended that efforts be made to avoid further spread of the disease in the study area. The following are therefore recommended to achieve this goal-

(i) Detection and treatment of infected individuals.

(ii). Periodic survey of water bodies for snail intermediate hosts and if detected, eradicated.

Public awareness campaign programme on schistosomiasis should be initiated in the
Construction of adequate toilet facilities, and education of the communities on the importance of proper disposal of human wastes (faeces andurine).
Provision of portable water to the masses by both State and Federal Governments to reduce contact/exposure to water bodies which may become infested with infective stage of the disease.
Water for domestic use should be protected from contamination with human urine and faeces, some of which may contain the eggs of schistosomes.

Immigrants into the area especially those from known endemic areas should be screened and treated if found
Vulnerable groups such as fishermen, irrigation workers and communities with high prevalence should have access to regular screening and treatment for schistosomiasis and appropriate prevention measures promoted within their respective working environments.
Policy makers should recognize the disease as a focal public health problem and should be willing to promote and support control where and when necessary.

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Aim