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In the Republic of Liberia, anti-Mg is a frequent finding. In this study, 17.6 per cent of 454 sera examined were found to have this blood group antibody.
Conjunctival lymphographies in patients infected with Onchocerca volvulus in Liberia showed normal or only slightly dilated lymphatics. The light-microscopical studies of conjunctival specimens revealed microfilariae predominantly in edematous dilated interstitial channels. Microfilariae in lymphatics and interstitial channels without endothelium of the conjunctivae were demonstrated by scanning and transmission electron microscopy. No signs of inflammatory cellular reaction were found in the vicinity of the parasites. In conclusion, the dilatation of lymphatics and interstitial channels as well as the pathways along which the microfilarial penetrated the cornea and the anterior segments of the eye are discussed.
A case-control study was carried out on 558 patients with malaria attending a hospital in Yekepa, northern Liberia; 94 patients (16.8%) were aged at least ten years, probably because of a low level of protective immunity in town dwellers due to malaria control. The proportion of sickle cell traits (1.8%) among the patient group was lower than in the population (7.2%) served by the hospital (chi 2, 21.455, 1 df, P less than 0.001). A stratified analysis showed the relative risk for Plasmodium falciparum malaria in sickle cell trait over normal homozygotes, as 0.29 (upper 95%) confidence interval, 0.56). For beta-thalassaemia trait, the proportion among patients was 5.5% as against 9.0% in the general population (chi 2, 6.158, 1 df, 0.025 greater than P greater than 0.010). Stratified analysis gave a weighted relative risk for beta-thalassaemia heterozygotes of 0.49 (upper 95% confidence interval, 0.74). Although there were four beta-thalassaemia traits in the 10-14 year stratum with moderate to high parasitaemias, we consider that the overall results are consistent with relative resistance against P. falciparum malaria of both sickle cell and beta-thalassaemia heterozygotes in this population. No conclusions were possible from this investigation with regard to HbC and the malaria hypothesis. We found no evidence that P. falciparum malaria elevates HbA2 concentrations into the beta-thalassaemia range.
In a study in northern Liberia of the malaria and beta-thalassaemia hypothesis, the frequencies of beta-thalassaemia and HbS traits were 9.1 and 3.4% in the Mano and 9.5 and 1.7% in the Gio tribal samples. HbC and HbN were present at low frequency. G6PD deficiency was found in 16% of males. An observed increase with age of beta-thalassaemia trait frequencies was consistent with the selection hypothesis. However, we could not entirely exclude that associated iron deficiency influenced the results in the six to 11 month age group. Malaria was holoendemic; Plasmodium falciparum predominated, P. malariae and P. ovale were also identified. Plasmodium falciparum prevalence rates were similar in normal and beta-thalassaemia trait children but parasite densities were consistently lower in the latter. Using the criterion of a falciparum parasite density of 1 x 10(9) 1(-1) or greater to indicate a potentially important infection, the relative risk in beta-thalassaemia traits one to four years old from the cross-sectional study was 0.45 (upper 95% confidence interval 0.79) and 0.41 (0.61) in two to nine year trait carriers from a longitudinal study. Plasmodium falciparum gametocyte rates were lower in beta-thalassaemia trait children (P less than 0.005). The geometric mean titre of P. falciparum antibodies was lower in beta-thalassaemia trait children from the one to four year group (P less than 0.05). Otherwise immunological studies showed little difference between the different Hb types. Parasitological findings were consistent with relative resistance of HbS trait carriers towards P. falciparum infection. We found no evidence for relative resistance of beta-thalassaemia traits towards P. malariae infection nor that G6PD deficient males were more resistant to P. falciparum than those with normal activity. We conclude that the results are consistent with relative resistance of beta-thalassaemia trait carriers to P. falciparum malaria.
An explanation was sought for the high prevalence of paragonimiasis in children in Liberia by examining possible modes of human infection from freshwater crabs. The occurrence, frequency of infection, and distribution of metacercariae of Paragonimus uterobilateralis in the freshwater crab Liberonautes latidactylus were studied. The muscles of the cephalothorax and of the legs were found to be the most frequently and most heavily infected parts of the crab. A likely risk of infection of children was considered to be the habit of chewing on, or ingesting in a raw state, the walking legs of infected crabs. Possible contamination of the hands of cooks with metacercariae from the internal organs or haemolymph of infected crabs was thought to be a minor route of infection.
This study examines the relationship between ethnicity and fertility in Liberia, within the context of the minority group status hypothesis. The hypothesis argues that minority group status exerts an independent effect on fertility, net of controls for socioeconomic and demographic variables. Using a subsample of women from the 1974 Liberian census, the study examines interethnic variations in fertility by comparing five ethnic minorities--Bassa, Vai, Grebo, Kru, Kpelle--with the majority group, Americo-Liberian. With the possible exception of Bassa women, the findings do not support the minority group status hypothesis. Instead, the findings are more congruent with the alternative assimilationist hypothesis which argues that when sociodemographic differences between majority and minority groups are controlled, their fertility levels should converge. The implications of these findings are explored.
Research was conducted in Liberia, West Africa to ascertain which hematinics produce the best Hb response in women during the 3rd trimester of pregnancy. After obtaining background information, each of the 621 subjects was randomly assigned to one of four treatment groups. Group 1 was given 60 mg iron once daily, group 2 was given 60 mg iron 3 times daily, group 3 was given 60 mg iron 3 times daily plus a 5-mg folic acid tablet once daily, and group 4 was given the same treatment as group 3 but also a weekly antimalarial prophylactic. For comparison, 58 untreated women in their 3rd trimester were also studied. Before therapy the five groups were similar with respect to selected socioeconomic status, health, and dietary variables. Hb response to therapy was measured at 4-wk intervals from the 24th wk of gestation until term. The Hb rises in all four treatment groups were significantly (p less than 0.001) higher than the base-line values at 4, 8, and 12 wk after the interventions. The percentage of anemic women was reduced from 78 to 45% over the 12 wk of supplementation. Hb rises in groups 3 and 4 were not significantly different from those in groups receiving iron alone. It is concluded that iron deficiency is the main cause of anemia in this population.
To estimate baseline infant and child mortality in Liberia, a survey was carried out in 1984 as part of the Combatting Childhood Communicable Diseases (CCCD) project. The project, a collaborative effort of the Liberian Ministry of Health, the US Agency for International Development, and the US Centers for Disease Control, is aimed at reducing childhood morbidity and mortality through oral rehydration therapy, vaccination and treatment for malaria. As a measure of programme impact, mortality estimates from this survey will be compared with those from a second survey after 4-5 years. A sample of 40 clusters (50-70 households per cluster) was used. The size is sufficient to detect a 25% reduction in mortality of children under 5 years of age. Mortality was estimated from a pregnancy history questionnaire asked of women aged 15-49 residing in cluster households. A reliability survey was conducted and pregnancies were matched to determine the level of omission of births and deaths. Results show a very high level of mortality with a risk of death in infancy above 20% and a risk of dying before the fifth birthday of one-third. Since the extent of omission of deaths in the first survey proved substantial, the reinterview survey was essential.
A baseline survey of childhood mortality in two counties of Liberia in 1984 found the risk of dying before age 5 to be almost one-third. Three years into the Combatting Childhood Communicable Diseases (CCCD) project, a survey using a pregnancy history questionnaire was conducted in the same clusters to determine if any change in mortality had occurred. Reinterviews were done in a subsample and pregnancies were matched from the two surveys to determine levels of missing events. After adjustment for omission, infant mortality was estimated at 180 per 1000, a 25% decline from the estimated 1984 level. Childhood mortality declined by an estimated 28%. Tabulations of death by reported cause using a verbal autopsy questionnaire showed that the risks of neonatal tetanus and fever associated deaths declined significantly. These reductions might have been a direct result of programme activities which were shown by a marked increase in tetanus toxoid immunization and access to antimalarial drugs in the study area.
Between October 1980 and August 1982, 100 patients in the pediatric population at Curran Lutheran Hospital, Zorzor, Liberia were identified as having multiple drug-resistant Salmonella enteritidis serotype enteritidis. The illness usually presented as an enteric fever but also as meningitis, gastroenteritis, empyema, subcutaneous abscesses, chronic otitis media, or a combination of these conditions. Predisposing factors were young age and debilitation from malnutrition or measles. The mortality of infected patients was 27.8%. The organism was originally misidentified as a Citrobacter species because of a delayed reaction on lysine decarboxylase medium. Incubation of the medium for five days resulted in a positive reaction that identified the organism as a Salmonella species. The isolates were resistant to multiple antibiotics. Genes mediating resistance were located on a 120-megadalton conjugative plasmid. A cryptic nonconjugative 40-megadalton plasmid was also present in several isolates.
To determine the influence of meterological factors on the diurnal biting cycle of Simulium yahense Vajime & Dunbar (a member of the Simulium damnosum Theoblad complex), we captured host-seeking females as they landed on the exposed lower legs of humans in the Harbel area of Liberia. Biting activity was greatest during the morning hours and was characterized by a unimodal harmonic curve. Although meteorological conditions had no decisive influence on the unimodal pattern of diurnal biting activity, hourly variation in the number of S. yahense captured at human bait was affected by meterological factors (i.e., the diurnal pattern of S. yahense biting activity is regulated by an internal clock, but the number of bits during any given hour is in response to meterological conditions). The transmission of Onchocerca volvulus (Leuckart) was highest during the morning hours when high transmission potentials were in phase with peak human activity and served to maintain the hyperendemicity of onchocerciasis in the Harbel area.
The first record of the African black widow spider, Latrodectus cinctus Blackwall, 1865 (= L. indistinctus Pickard-Cambridge, 1904) from Liberia is presented. It is a further record of a savanna species in the forest zone of West Africa. Increasing deforestation may cause expansion of the ranges of savanna-inhabiting animal species into the forest zone.
Sera from 32 adult men residing in a malaria holoendemic area of Liberia were investigated for seroreactivities to different asexual blood-stage malaria antigens on five consecutive occasions from 1984 to 1986. The seroreactivities to crude parasitic antigens and to Pf 155/RESA (EMIF) were determined by immunofluorescence and to repetitive sequences of Pf 155/RESA by enzyme-linked immunosorbent assay (ELISA). All sera were highly reactive against the crude parasitic antigens with reciprocal titres varying from 5000 to 100,000. The EMIF titres showed a wider variation from negative (less than 10) to 25,000, and when the same individuals were re-examined on subsequent surveys similar EMIF titres were found. The ELISA seroreactivities to three different repetitive sequences of Pf 155/RESA also showed different individual profiles which were rather consistent on consecutive surveys. High EMIF titres appeared to be correlated mainly to one of the peptide sequences, namely (EENV)2. The consistent individual profiles of the seroreactivities to Pf 155 and its repetitive sequences suggest genetic restriction of the humoral immune response. Although no significant correlation was found between EMIF titres and parasitic densities in the adult hyperimmune men the specific peptides, however, offer new possibilities of further investigating protective capacities of different immune responses to specific epitopes of the malaria parasite.
Communicable diseases are of particular concern in conflict and disaster-affected populations that reside in camp settings. In the acute emergency phase, diarrhoeal diseases have accounted for more than 40% of deaths among camp residents. Clear limitations exist in current water treatment technologies, and few products are capable of treating turbid water. We describe the findings of a 12-week effectiveness study of point-of-use water treatment with a flocculant-disinfectant among 400 households in camps for displaced populations in Monrovia, Liberia. In intervention households, point-of-use water treatment with the flocculant-disinfectant plus improved storage reduced diarrhoea incidence by 90% and prevalence by 83%, when compared with control households with improved water storage alone. Among the intervention group, residual chlorine levels met or exceeded Sphere standards in 85% (95% CI: 83.1-86.8) of observations with a 95% compliance rate.
Haemoglobin components in 21 Liberians with Hb S beta +-thalassaemia and four with Hb C beta +-thalassaemia were measured to classify the forms of beta +-thalassaemia present in the population. In 20 Hb S and all Hb C beta +-thalassaemics the data were consistent with the interaction of these variants with the mild type 2 (Negro) form of beta +-thalassaemia. The data available were insufficient to classify the remaining case, a young child. It was concluded that the clinically more severe type of beta +-thalassaemia giving Hb A levels of 5 to 15% in compound heterozygotes is probably uncommon in Liberia.
Simulium yahense black flies infected with microfilaria of Onchocerca volvulus were kept in a defined insectary environment in Liberia, West Africa. A daily sample of infected flies was dissected for larvae developing in the thoracic muscles and examined for growth in stadial development. Microfilariae ingested by black flies transformed to the L1 larval stage without molting. Successive larval development included molting to the L2 stage and, finally, to the L3 stage, which was infective in humans. The cephalic cap, consisting of a laterally located hook and central stoma, occurs in the first larval stage. The caudal appendix and the laterally located anal opening are apparent in the L1 larva. In the L2 stage, the cephalic cap is lost and the large circular stoma becomes surrounded with elevated flaps. The caudal appendix was lost after larvae molted to the L3 stage, and in its place, 3 terminal papillae developed. Sense organs, such as 2 opposing phasmids and 8 papillae that were arranged into 2 circles, developed in the cephalic region of the L3 larva. The evidence of pathological consequences due to the presence of the L3 larva in the fly host are illustrated and discussed.
In vitro tests of Plasmodium falciparum susceptibility to chloroquine were performed in May 1982 in Yekepa area, northern Liberia where several previous in vivo investigations had shown full susceptibility. The isolates from 19 subjects were studied. 18 Rieckmann 24-h micro tests were successful. Effective chloroquine concentrations by probit analysis were 0.3 microM for 50% inhibition (EC50) and 1.2 microM for 99% inhibition (EC99). 18 of the 48-h tests were successful. 10 isolates were inhibited by 0.75 microM chloroquine and another 8 by 2.5 microM.
Seasonal changes in populations of Biomphalaria pfeifferi and Bulinus globosus were observed at 62 locations in Liberia, West Africa. All varieties of water in both urban and rural locations were sampled. A wet season decrease and dry season increase of B. globosus populations in both urban and rural locations, similar to that reported elsewhere in West Africa, was observed. Similar fluctuations of B. pfeifferi populations were noted. The prevalence of schistosome infected vector snails varied markedly between rural and urban locations. At rural sites parasite prevalence followed the appropriate vector snail prevalence. At urban sites a portion of the vector snail population appeared relatively unaffected by seasonal changes. This stable population harbors a reservoir of infected snails that sustain year round transmission. Human infection was sampled in school children in the study area and prevalence of approximately 50% was found for both Schistosoma mansoni and S. haematobium. Added to the malacologic information this suggests less than hyperendemic transmission. The data suggest that urban environments should receive priorities for control programs.