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Biomedical subjects

C N Macpherson

Publications and source records attributed to C N Macpherson.

31 records · Page 2Linked to original sources
PubMed1986

Hepatitis delta virus infection in Kenya. Its geographic and tribal distribution.

In 1982-1984, an epidemiologic survey of the prevalence of hepatitis B virus surface antigen (HBsAg) in circulating blood (HBs-antigenemia) and of hepatitis delta virus infection was performed in Kenya. The distributions of hepatitis B virus and the delta virus were shown to be very variable. In southern Kenya, only two of 202 sera from HBsAg-positive individuals with no known liver disease and none from 123 HBsAg-positive patients with hepatitis B-related liver disease were positive for delta antibody. In contrast, in northern Kenya, there was an overall prevalence of delta antibody in healthy individuals of 31%. The distribution of delta infection is discussed in relation to lifestyle, ethnic group, and geographic area.

Adult↗
PubMed1986

The identification of eggs of Echinococcus by immunofluorescence using a specific anti-oncospheral monoclonal antibody.

A relatively simple and specific test has been developed to distinguish eggs of Echinococcus from those of other morphologically identical taeniid species. A specific anti-Echinococcus oncosphere monoclonal antibody was produced which binds in an indirect immunofluorescence test to egg-derived oncospheres of E. granulosus but not to those of other taeniid species, such as Taenia hydatigena, T. saginata, T. pisiformis, T. ovis, T. multiceps, or T. taeniaeformis. Specific fluorescence was obtained with oncospheres of E. granulosus derived from either hatch/activated viable eggs using artificial intestinal fluid or from hypochlorite/detergent treated eggs. The potential use of this test in the study of the transmission of Echinococcus in Turkana, Kenya, is discussed.

Animals↗
PubMed1985

Epidemiology of hydatid disease in Kenya: a study of the domestic intermediate hosts in Masailand.

The results are given of a study on the epidemiological significance of cattle, sheep and goats in maintaining the life-cycle of Echinococcus granulosus in Masailand, Kenya. A total of 134 (8.9%) of 1499 cattle, 146 (8.1%) of 1798 sheep and 144 (7.1%) of 2020 goats slaughtered in abattoirs in Masailand were found to harbour hydatid cysts. The frequency distribution of the hydatid cysts in each intermediate host species was over-dispersed. Of 729 cattle cysts examined 71 (9.7%) were fertile (cyst contained protoscoleces) with an average viability of 71%, 507 (69.5%) were sterile and 151 (20.7%) were calcified. Out of 810 sheep and 451 goat cysts examined 571 (70.5%) and 213 (47.0%) were fertile with respective viabilities of 88% and 86% and 143 (17.7%) and 194 (43.0%) were sterile leaving 96 (11.6%) and 45 (10.0%) sheep and goat cysts which were calcified. The greater fertility of the sheep and, to a lesser extent, goat cysts coupled with the reported greater infectivity of sheep and goat than cattle material to dogs and the common Masai practice of slaughtering sheep and goats at home, indicates that, at present, sheep and goats are the most important intermediate hosts for the maintenance of the domestic life-cycle of E. granulosus in Masailand. The incidence of hydatidosis in donkeys and the relationship of the domestic cycle to the wildlife cycle operating in the same area is unknown and requires further study.

Animals↗
PubMed1985

Hydatid disease in the Turkana District of Kenya, IV. The prevalence of Echinococcus granulosus infections in dogs, and observations on the role of the dog in the lifestyle of the Turkana.

The prevalence of Echinococcus granulosus in dogs in the Turkana District of Kenya was 39.4% of 695 examined. Of these, 98 (35.8%) had heavy Echinococcus worm burdens (10(3)-5 X 10(4) ), while 54 (19.7%) and 122 (44.5%) had medium (201-1000) and light (1-200) burdens. The possible sources of these infections are discussed. The prevalence rate differed in various parts of the district, ranging from 63.5% in the northwest, where the highest incidence of human hydatidosis also occurs, to nil along the shores of Lake Turkana. Infection rates of 32.0% and 16.7% were recorded at Lokitaung (north-east) and Lodwar (central), while in the south 48.9% of dogs harboured Echinococcus. This latter figure is surprising as the area has a low incidence of human hydatidosis. The Turkana keep a large number of dogs, and the reasons for this and the social role of the dog in the district is discussed. No difference in susceptibility was found between Turkana-type dogs and those of mixed breeds from Nairobi when they were experimentally infected with hydatid protoscolices from man, camels, cattle, sheep and goats. However, it proved difficult to infect the Turkana-type of dogs with viable protoscolices of cattle origin. The reasons for this and its epidemiological implications remain unclear. It is suggested that droughts, which affect Turkana every six to ten years, may play an important role in the perpetuation of hydatid disease in the area.

Animals↗
PubMed1983

An active intermediate host role for man in the life cycle of Echinococcus granulosus in Turkana, Kenya.

Hydatid material removed at operation from 97 Turkana was compared for fertility and viability with hydatid material removed from camels, cattle, sheep, and goats. The results showed that the human material was extremely fertile and viable, as was material from the camels, goats, and sheep. Cattle cysts were invariably sterile, and the protoscoleces, when present, were comparatively less viable. The high incidence and fertility of hydatid cysts in the Turkana, together with the lack of burial customs thus allowing dogs to have ready access to infected human corpses, means that the Turkana are potential biological participants in the cyclic transmission of Echinococcus granulosus in this region. This is a unique situation, for elsewhere in the world man is regarded as an accidental host who plays no role in the parasite's life cycle.

Adolescent↗
PubMed1981

The existence of Dracunculus medinensis (Linnaeus, 1758) in Turkana, Kenya.

Dracontiasis has been previously reported in southern Sudan, northern Uganda and north-west Eritrea but this is the first report of autochthonous cases in Turkana, Kenya. Five Turkana tribesmen, three females from the same family, one young boy and an adult male were being treated for guinea-worm at the dispensary in Lokichogio, northern Turkana District. The three women had recently returned from southern Sudan, where the disease is endemic, but the two male tribesmen had only lived in and around the Lokichogio region. The methods used in obtaining water from water-holes dug in dry river beds provide an ideal situation for Dracunculus transmission amongst the tribesmen; this parasite may therefore become a problem in this remote impoverished area.

Adult↗
PubMedDate not supplied

Pastoralists and hydatid disease: an ultrasound scanning prevalence survey in east Africa.

An attempt was made to estimate the prevalence of hydatid disease in nomadic pastoralists living in eastern Africa and to identify environmental, cultural and behavioural factors which may influence Echinococcus transmission. 18,565 nomadic pastoralists, from 12 different groups living in the vast, semi-desert regions of Kenya, Sudan, Ethiopia and Tanzania, were screened for hydatid cysts using a portable ultrasound scanner. High prevalences of hydatidosis were recorded among the north-western (5.6%) and north-eastern (2.1%) Turkana of north-west Kenya, the Toposa (3.2%) of southern Sudan, the Nyangatom (2.2%), Hamar (0.5%) and Boran (1.8%) of south-west Ethiopia and northern Kenya and the Maasai (1.0%) of Tanzania. Lower prevalences were recorded amongst the southern (0.3%) and lake dwelling (0.3%) Turkana and the Pokot (0.1%) of Kenya. The disease was not found amongst the Turkana, Samburu, Dassanetch, Gabbra, Somali or Rendille screened on the east side of Lake Turkana. The scanning surveys were well accepted by the people and provided evidence for the need to expand the present hydatid control programme in Turkana to cover the whole hyperendemic focus. Such a programme must contain an educational component for, although most groups recognized hydatid cysts, there was complete lack of knowledge concerning the parasite and its mode of transmission.

Africa, Eastern↗
PubMedDate not supplied

In vitro resistance patterns of Plasmodium falciparum to chloroquine--a reflection of strain-specific immunity?

Studies in vitro among children on the response of Plasmodium falciparum to chloroquine were conducted as part of the national long-term monitoring of drug resistance in a holo- to hyperendemic malarious area of Tanzania between 1983 and 1989. Overall, no significant increase in chloroquine resistance was observed. However, in children under 5 years old resistance increased during this period, whereas in schoolchildren resistance decreased from 1986 to 1989. A hypothesis based on antigenic differences between resistant and sensitive strains is proposed to explain this age-specific pattern. If immunity develops principally against the most frequent parasite strains, then as it develops the numbers of the most frequent strains will be reduced, whilst, the rare strains may become predominant and thus be detected in the blood of immune patients. Thus, in an endemic area, the observed resistance pattern in non-immune infants will differ from that in immune schoolchildren, as was observed in the present study. These findings may have important implications for the control of malaria and the development of vaccines.

Adolescent↗
PubMedDate not supplied

Cystic echinococcosis in semi-nomadic pastoral communities in north-west China.

In order to determine the prevalence of human cystic echinococcosis (CE) in semi-nomadic traditional pastoralist groups in north-west China, 2 large community studies were undertaken in Altai and Tacheng Prefectures in 1990/91 and 1995/96, respectively. The Kekergash community (Altai) comprised mainly ethnic Kazakhs, whereas the Narenhebuke community (Tacheng) comprised mainly Mongolians. Populations were screened for CE by abdominal ultrasound scan (US) and serological tests. The total prevalence of confirmed human CE was higher in Narenhebuke (2.7%, 49/1844) than in Kekergash (0.9%, 17/1861; P < 0.01). Within each community there was no significant difference of CE prevalence between the Kazakh and Mongolian groups, although Han Chinese exhibited twice the rate of CE (4.9%) in Narenhebuke compared to the dominant Mongolian population. For each community, human CE prevalence increased with age and there was a greater risk associated with the practice of home slaughter of livestock. Dogs were screened for Echinococcus granulosus infection and re-infection levels using a highly specific coproantigen test. The proportion of dogs with positive coproantigen tests was significantly higher in Narenhebuke (36.0%, 50/139) compared to Kekergash (17.8%, 16/90). In Narenhebuke the re-infection levels of dogs, as determined by coproantigen positivity, were higher in the winter quarters (49.4%, 39/79) compared to the summer quarters (18.3%, 11/60; P < 0.01). Furthermore, coproantigen re-test positivity was 25% at 3 months and 29.2% at 7 months. Highest dog coproantigen positivity was obtained over the winter period.

Adolescent↗