Leishmaniasis in The Gambia. 2. A study of possible vectors and animal reservoirs,with the first report of a case of canine leishmaniasis in The Gambia

Following the detection of two cases of leishmaniasis in The Gambia, the possible vectors and animal reservoirs were studied. A total of 5, 158 phlebotomine sandflies, in 20 species and subspecies were captured, including 98 males and 61 females of Phlebotomus duboscqi. This species is a vector of cutaneous leishmaniasis in Senegal and must be suspected as a vector in The Gambia; it was captured close to the dwellings of both patients and from rodent burrows, including those of Mastomys erythroleucus, a known reservoir of cutaneous leishmaniasis in Senegal.We report the first finding in The Gambia of visceral leishmaniasis in a dog captured near the house of the patient with visceral leishmaniasis. This strongly suggests that dogs could be a reservoir of this infection in this area. The vector was not determined.     

Malaria Prevalence among Young Infants in Different Transmission Settings,Africa

The prevalence and consequences of malaria among infants are not well characterized and may be underestimated. A better understanding of the risk for malaria in early infancy is critical for drug development and informed decision making. In a cross-sectional survey in Guinea, The Gambia, and Benin, countries with different malaria transmission intensities, the overall prevalence of malaria among infants <6 months of age was 11.8% (Guinea, 21.7%; The Gambia, 3.7%; and Benin, 10.2%). Seroprevalence ranged from 5.7% in The Gambia to 41.6% in Guinea. Mean parasite densities in infants were significantly lower than those in children 1–9 years of age in The Gambia (p<0.0001) and Benin (p = 0.0021). Malaria in infants was significantly associated with fever or recent history of fever (p = 0.007) and anemia (p = 0.001). Targeted preventive interventions, adequate drug formulations, and treatment guidelines are needed to address the sizeable prevalence of malaria among young infants in malaria-endemic countries.     

Intense and Mild First Epidemic Wave of Coronavirus Disease,The Gambia

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is evolving differently in Africa than in other regions. Africa has lower SARS-CoV-2 transmission rates and milder clinical manifestations. Detailed SARS-CoV-2 epidemiologic data are needed in Africa. We used publicly available data to calculate SARS-CoV-2 infections per 1,000 persons in The Gambia. We evaluated transmission rates among 1,366 employees of the Medical Research Council Unit The Gambia (MRCG), where systematic surveillance of symptomatic cases and contact tracing were implemented. By September 30, 2020, The Gambia had identified 3,579 SARS-CoV-2 cases, including 115 deaths; 67% of cases were identified in August. Among infections, MRCG staff accounted for 191 cases; all were asymptomatic or mild. The cumulative incidence rate among nonclinical MRCG staff was 124 infections/1,000 persons, which is >80-fold higher than estimates of diagnosed cases among the population. Systematic surveillance and seroepidemiologic surveys are needed to clarify the extent of SARS-CoV-2 transmission in Africa.     

Mixed populations of Bulinus senegalensis (Muller) and Bulinus forskali (Ehrenburg) (Mollusca: Planorbidae) in The Gambia

A brief survey of alluvial pools and irrigated ricefields in The Gambia shows that the distribution of Bulinus senegalensis is not confined to laterite pools and is similar to that in neighbouring Senegal. B. senegalensis was found in every site at least once, alone or with B. forskali. The proportion of the two species varies during the season and from year to year. It is no longer necessary to consider B. forskali as a natural host of S. haematobium.     

S-antigens and isozymes in strains of Plasmodium falciparum

Evidence was found for the independent reassortment of parasite genes for S-antigens and isozymes. The Lagos and Palo Alto strains of Plasmodium falciparum had the same isozyme forms of PGD and LDH but different S-antigens. In contrast, the BW (Gambia) and Palo Alto strains had different isozyme forms of GDH but shared some S-antigens. From artificial mixtures of parasites with different isozymes of GDH and different S-antigens, clones were derived in vitro which had a single isozyme type of GDH and a single type of S-antigen.     

Therapeutic landscapes of the Jola, The Gambia, West Africa

This paper contributes to the 'new' medical geography through its analysis of the therapeutic landscapes of the Jola of The Gambia. The paper advances the debate surrounding the conceptualization of medicine and health through a review of literature on African medicinal systems; it examines in detail the health care system of the Jola of The Gambia, documenting indigenous human and ethnoveterinary medical beliefs and practices and focusing in particular on the role of herbal medicine; and it discusses the interactions and links between indigenous medicine and biomedicine, thus demonstrating the importance of placing an understanding of health care systems in different places within an awareness of global power relations. The paper therefore links cultural perspectives with a political economy analysis, to highlight the importance of place and specificity of cultural context when investigating health care beliefs and practices. The intention of the paper is to present a theoretically informed empirical case study which reinforces the practical value of a 'new' medical geography.     

Combined immunization of infants with oral and inactivated poliovirus vaccines: results of a randomized trial in The Gambia, Oman, and Thailand. WHO Collaborative Study Group on Oral and Inactivated Poliovirus Vaccines.

To assess an immunization schedule combining oral (OPV) and inactivated poliovirus vaccines (IPV), we conducted a clinical trial in the Gambia, Oman, and Thailand. Children were randomized to receive one of the following schedules: OPV at birth, 6, 10, and 14 weeks of age; OPV at birth followed by both OPV and IPV at 6, 10, and 14 weeks of age: or placebo at birth followed by IPV at 6, 10, and 14 weeks of age. A total of 1685 infants were enrolled; 24-week serum specimens were available for 1291 infants (77%). Across the study sites at 24 weeks of age, the proportion of seropositive children in the combined schedule group was 95-99% for type 1, 99-100% for type 2, and 97-100% for type 3. In the Gambia and Oman, the combined schedule performed significantly better than OPV for type 1 (95-97% versus 88-90%) and type 3 (97-99% versus 72-73%). In the Gambia and Oman, seroprevalences in the IPV group were lower for type 1 (significantly lower in the Gambia); significantly lower for type 2; and significantly higher for type 3, compared with the OPV group. In Thailand, the IPV group had significantly lower proportions of children who were seropositive for each of the three types, compared with the OPV group. The responses to OPV in the Gambia, Oman, and Thailand were consistent with previous studies from these countries. IPV given at 6, 10, and 14 weeks of age provided inadequate serological protection against poliovirus, especially type 1. The combined schedule provided the highest levels of serum antibody response, with mucosal immunity equivalent to that produced by OPV alone.     

Transmission of Armillifer armillatus ova at snake farm, The Gambia, West Africa

Visceral pentastomiasis caused by Armillifer armillatus larvae was diagnosed in 2 dogs in The Gambia. Parasites were subjected to PCR; phylogenetic analysis confirmed relatedness with branchiurans/crustaceans. Our investigation highlights transmission of infective A. armillatus ova to dogs and, by serologic evidence, also to 1 human, demonstrating a public health concern.     

The etiology of lobar pneumonia in the Gambia

Sixty-four patients who had been admitted to hospital in the Gambia with acute lobar pneumonia were investigated. Lung aspiration proved to be the most effective method of establishing a bacterial etiology, and Streptococcus pneumoniae was the pathogen isolated most frequently from patients irrespective of age. Among children, Haemophilus influenzae, either singly or in combination with another bacterial agent, was an important cause of pneumonia. Of 13 isolates of H. influenzae two were of serotype a, while four others were non-capsulated. All isolates of S. pneumoniae and H. influenzae were sensitive to penicillin.     

Participatory approach to identify interventions to improve the health,safety, and work productivity of smallholder women vegetable farmers in the Gambia

Objective  

This paper describes the qualitative, community-based participatory approach used to identify culturally-acceptable and sustainable interventions to improve the occupational health, safety, and productivity of smallholder women vegetable farmers in The Gambia (West Africa).     

A comparison of the prevalence of Campylobacter,Shigellae and Salmonellae in faeces of malnourished and well nourished children in The Gambia and Northern Nigeria

The proportion of children in whom bacterial pathogens were isolated in faeces was compared in 59 malnourished and 59 age-matched well nourished children in Fajara, The Gambia, with 38 malnourished and 38 age-matched well nourished children in Malumfashi, Northern Nigeria. Campylobacters were identified more frequently in malnourished (10·2%) and well nourished (6·8%) children in The Gambia than in malnourished (2·6%) and well nourished (2·6%) children in Nigeria. Salmonellae were more frequently isolated in the malnourished Nigerian children (28·9%) than in the malnourished Gambian children (3·4%) and were present in similar proportions (5·1% and 5·3%) in well nourished children in both communities. Shigellae were isolated in a few individuals in each group. The differences in the epidemiology of these enteropathogens are discussed with respect to the differences in ecology between these two sub-Saharan, savanna communities.     

Two pathways to kwashiorkor?

Comparisons, based on anthropometric and biochemical measurements, have been made between Gambian and Ugandan children with kwashiorkor, and Gambian children with marasmus. Cases of kwashiorkor and marasmus in The Gambia were very similar both anthropometrically and in their plasma hormone and amino-acid patterns, but quite different in these respects from kwashiorkor in Uganda. Additional data from a prospective longitudinal study recently completed in The Gambia indicated that, when it occurred, hypoalbuminaemia appeared acutely, in contrast to the gradual development observed in Uganda. These findings suggest that kwashiorkor in The Gambia and in Uganda have distinct aetiologies and possible reasons for the difference in pathophysiologies are discussed. In particular the association of hypoalbuminaemia with diarrhoeal disease in The Gambia indicates that plasma protein loss from the gastro-intestinal tract could be a factor precipitating kwashiorkor in children who would otherwise be regarded as cases of marasmus.     

Leishmaniasis in The Gambia. 3. Is its incidence increasing?

During 1982 a further case of visceral leishmaniasis and six cases of cutaneous leishmaniasis were seen at the Medical Research Council Laboratories in The Gambia, suggesting that the incidence of this infection in The Gambia is increasing.     

Miniature anion-exchange/centrifugation technique for the diagnosis of microfilaraemia in the field

The miniature anion-exchange/centrifugation (AEC) technique, developed originally for the detection of low parasitaemias in laboratory rodents, was adapted to field use for the diagnosis of trypanosomiasis in man in Africa and was tested in The Gambia. During this field study it was found that microfilariae of Dipetalonema perstans could also pass through the anion exchange column and appear in the centrifugate as ‘medusa heads’.One locality-group (Mansafa Bolon) showed a generally higher prevalence and prevalences in women over 40 years old were higher than in the corresponding male groups in every locality. The potential usefulness of this technique in epidemiological studies of filariasis and ways of improving the accuracy of numerical estimates are briefly discussed.     

Human antibody responses to A and C capsular polysaccharides, IgA1 protease and transferrin-binding protein complex stimulated by infection with Neisseria meningitidis of subgroup IV-1 or ET-37 complex

The protein sequences of the IgA1 protease, TbpA and TbpB proteins differ between meningococci representative of serogroup A, subgroup IV-1 from epidemic disease in The Gambia and serogroup C, ET-37 complex from endemic disease in Mali. The uniformity of restriction endonuclease sites was determined for the iga, tbpA and thpB genes among strains of both clonal lineages. Rare isolates had acquired a variant thpAB operon by horizontal genetic exchange but all other strains were uniform within each clonal lineage. The quantitative levels of IgG to capsular polysaccharide, IgA1 protease and TBP complex were measured in paired acute phase and convalescent phase sera from The Gambia and from Mali using antigens from the homologous clonal lineages. IgG levels to these antigens were also measured in paired sera from healthy Gambians who permanently carried meningococci in the nasopharynx or did not. The results showed that disease stimulated IgG to each antigen in Mali and to all but TBP complex in The Gambia. Similarly, higher levels of IgG were found in sera from permanent carriers than in sera from permanent non-carriers. Acute phase sera from Mali contained low levels of IgG to C capsular polysaccharide (geometric mean value of 0.3 microg ml(-1)) while such sera from The Gambia contained higher and potentially protective levels of IgG to A polysaccharide (geometric mean of 5.5 microg ml(-1)). The concentrations of IgG to TBP complex in acute phase sera were higher and IgG to IgA1 protease was even higher, suggesting that intermediate levels of IgG to these proteins do not protect against disease.     

Preparation for a pneumococcal vaccine trial in The Gambia: individual or community randomisation?

In preparation for a large phase-3 trial of pneumococcal polysaccharide/conjugate vaccine among infants in The Gambia, the relative merits of community and individual randomisation were considered. The impact of vaccination might be enhanced in a community randomised trial if there was a substantial 'herd' effect. This might occur if those vaccinated comprise a substantial proportion of potential transmitters of infection. However, there are few data on the sources of pneumococcal infections in The Gambia and with the high degree of mobility of people in The Gambia, it seems unlikely that any herd effect would be strong. In the absence of a herd effect, a community-randomised trial would have lower power for the mortality end-points compared to an individually randomised trial of the same size. In addition, a community-randomised trial might not provide sufficient control against potential confounders and blinding might be difficult to sustain if the vaccine has a strong effect. An individually randomised trial seems a better strategy under the conditions prevailing in The Gambia.     

Estimates of the infectious reservoir of Plasmodium falciparum malaria in The Gambia and in Tanzania

Separate studies carried out in Farafenni, The Gambia and Ifakara, Tanzania in 1990-94 provided comparative data on population age structure, population gametocyte prevalences and gametocyte carrier infectivity. The percentage of the population estimated to be infective to mosquitoes was 5.5% and 3.8% in The Gambia and Tanzania, respectively. The age groups 1-4 years, 5-9 years, 10-19 years and 20 years or more comprised 17.5%, 21.7%, 22.2% and 37.9%, respectively, of the infectious population in The Gambia; the corresponding figures for Tanzania were 30.9%, 25.2%, 15.7% and 28.1%. These figures are in broad agreement with those from other published studies which estimated the infectious reservoir directly and suggest that adults contribute significantly to the infectious reservoir of malaria, particularly in areas of intense seasonal transmission. Control measures aimed at reduction of transmission may have only a limited effect in areas of moderate seasonal transmission if directed only at children.     

Factors affecting transmission of Wuchereria bancrofti by anopheline mosquitoes. 4. Facilitation, limitation, proportionality and their epidemiological significance.

Quantitative understanding of the transmission dynamics of lymphatic filarial parasites is essential for the rational planning of control strategies. One of the most important determinants of transmission dynamics is the relationship between parasite yield, the success rate of ingested microfilariae (mf) becoming infective larvae in a mosquito vector, and mf density in the source of the human blood meal. Three types of relationship have been recognized in human filaria/mosquito couples--limitation, facilitation and proportionality; facilitation has hitherto been observed only in the couple Wuchereria bancrofti/Anopheles gambiae in Burkina Faso, in experimental studies on a high density mf carrier. The present paper demonstrates facilitation in W. bancrofti/An. gambiae and W. bancrofti/An. arabiensis in lower mf density carriers in The Gambia and Tanzania, and in W. bancrofti/An. funestus in Tanzania. Facilitation was not found in An. melas in The Gambia nor in An. merus in Tanzania. Analysis of published data shows limitation at low level mf densities in W. bancrofti/Culex quinquefasciatus in Sri Lanka, and in the same couple in India. Limitation also occurs in Brugia malayi/Aedes togoi in experimental cats; proportionality occurs in B. malayi/Mansonia bonneae in Malaysia. The epidemiological significance of these host/parasite relationships is discussed, and supporting evidence for its validity is presented from the published results of large-scale control programmes.     

Meeting oxygen needs in Africa: an options analysis from the?Gambia

Objective

To compare oxygen supply options for health facilities in the Gambia and develop a decision-making algorithm for choosing oxygen delivery systems in Africa and the rest of the developing world.

Methods

Oxygen cylinders and concentrators were compared in terms of functionality and cost. Interviews with key informants using locally developed and adapted WHO instruments, operational assessments, cost-modelling and cost measurements were undertaken to determine whether oxygen cylinders or concentrators were the better choice. An algorithm and a software tool to guide the choice of oxygen delivery system were constructed.

Findings

In the Gambia, oxygen concentrators have significant advantages compared to cylinders where power is reliable; in other settings, cylinders are preferable as long as transporting them is feasible. Cylinder costs are greatly influenced by leakage, which is common, whereas concentrator costs are affected by the cost of power far more than by capital costs. Only two of 12 facilities in the Gambia were found suitable for concentrators; at the remaining 10 facilities, cylinders were the better option.

Conclusion

Neither concentrators nor cylinders are well suited to every situation, but a simple options assessment can determine which is better in each setting. Nationally this would result in improved supply and lower costs by comparison with conventional cylinders alone, although ensuring a reliable supply would remain a challenge. The decision algorithm and software tool designed for the Gambia could be applied in other developing countries.