Tropical Medicine and International Health
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Immunization against diseases caused by <i>Theileria parva</i>: a review Summary Theileria parva is the causative agent of three epidemiologically different diseases, East Coast fever (ECF), Corridor disease and January disease, caused by 3 types of T. parva , T. p. parva , T. p. lawrencei and T. p. bovis , respectively. The history of immunization against these diseases has been marked by salient discoveries such as the immune status in recovered animals, the activity of tetracyclines during the incubation period, the possibility for cryopreserving supernatant of prefed ticks and the development of useful serological tests. The possibility of simultaneous administration of stabilate and long‐acting tetracycline have greatly contributed to making the infection and treatment method operational. The importance of antigenic diversity in T. parva has been reflected in the difficulties related to the selection of the immunizing stock or combinations of stocks: a ‘cocktail’ of East African isolates may give broad protection against field challenge by ECF (T. parva parva ), but Corridor disease is more problematic. On the other hand, certain single isolates may give equally good protection against ECF field challenge. Studies on the immunology of T. parva infection and the application of molecular tools have led to the discovery that sera of recovered animals neutralize sporozoites of various isolates, and to the p67 molecular vaccine; yet so far the only available method of immunizing against T. parva infections is the infection and treatment method or, in the case of T. parva bovis , the use of sublethal stabilate doses. Infection and treatment is applied on a fairly large scale in Zambia, and on a more limited scale in a few other countries. Immunity by this rather crude method is long‐lasting and solid, but cross‐immunity problems against some field strains remain. Furthermore, as immunized animals remain carriers, immunization may contribute to attaining and improving endemic stability in endemic areas in indigenous breeds with an adequate level of genetic tolerance to ECF. On the other hand, carrier animals may constitute a risk for spreading the disease into ECF‐free areas where the vector is present. Other disadvantages of the method are that immunization of cattle during the incubation of naturally contracted East Coast fever will not prevent the disease and jeopardize its reputation. Furthermore, stabilates have to be cryopreserved, often a technical drawback, and contamination with undesirable pathogens may occur in tick‐derived material. Therefore the need remains for the development of effective molecular vaccines and it must be remembered that immunization must be cost‐effective and sustainable and it is only one aspect of integrated control of theileriosis and other tick‐borne diseases. There is no universally valid strategy. Several factors have to be considered: value and susceptibility of cattle to theileriosis and to other tick‐borne and tick‐associated diseases, infestation by various ticks present in the area, the type of theileriosis (ECF, Corridor disease or January disease) and the epidemiological situation where immunization is taking place. The optimal age for immunization of the calves in endemic areas needs to be determined: when calf mortality by naturally occurring theileriosis is a problem, the sooner calves are immunized the better, but a proportion will have contracted natural infection before they can be reached, and immunization of very young calves might not be fully effective.
Tropical Medicine and International Health - Tập 4 Số 9 - 1999
Short communication: Post‐kala‐azar dermal leishmaniasis – an appraisal Summary This short descriptive paper assesses diagnostics, clinical characteristics and therapy of both Indian and African post‐kala‐azar dermal leishmaniasis.
Tropical Medicine and International Health - Tập 12 Số 7 - Trang 848-851 - 2007
Konzo associated with war in Mozambique We report an epidemic of konzo, symmetric spastic paraparesis associated with cassava consumption and cyanide exposure: 384 patients were treated in rehabilitation centres; the prevalence rate in a badly affected area was 30/1000. Most patients were children over 3 and women. Owing to war, communities turned to bitter cassava as their staple and took shortcuts in its processing. When the war ended, they continued to depend on inadequately processed bitter cassava. The epidemic lasted 2 years (the last year of war and the first of peace) with peaks each year during the cassava harvest. Although most cases were reported from rural inland areas, patients also came from small towns and the coast. School children had raised urinary thiocyanate and linamarin and low inorganic sulphate concentrations. Urinary thiocyanate values were lower than those previously reported in konzo epidemics, probably because we collected specimens before the cassava harvest and epidemic peak. The necessary conditions for konzo were present: intensive cultivation of bitter cassava, insufficient processing, a probable high cyanide intake, and a low intake of protein‐rich foods.
Tropical Medicine and International Health - Tập 2 Số 11 - Trang 1068-1074 - 1997
Malaria morbidity, treatment‐seeking behaviour, and mortality in a cohort of young children in rural Burkina Faso Summary Objective Methods results conclusions
Tropical Medicine and International Health - Tập 8 Số 4 - Trang 290-296 - 2003
Early treatment of childhood fevers with pre‐packaged antimalarial drugs in the home reduces severe malaria morbidity in Burkina Faso Summary In rural, malaria‐endemic Burkina Faso, we evaluated the impact of the use of pre‐packaged antimalarial drugs (PPAM), by mothers in the home, on the progression of disease in children from uncomplicated fever to severe malaria. In each village of one province, a core group of opinion leaders (mainly older mothers) was trained in the management of uncomplicated malaria, including the administration of PPAM. Full courses of antimalarial (chloroquine) and antipyretic (aspirin) drugs were packaged in age‐specific bags and made widely available through community health workers who were supplied through the existing drug distribution system. Drugs were sold under a cost‐recovery scheme. Local schoolteachers conducted surveys in a random sample of 32 villages at the end of the high transmission seasons in 1998 and 1999. Disease history and the treatment received were investigated for all children under the age of 6 years having suffered from a fever episode in the previous 4 weeks. ‘Uncomplicated malaria’ was defined as every episode of fever and ‘severe malaria’ as every episode of fever followed by convulsions or loss of consciousness. During the study period, 56%[95% confidence interval (CI) 50–62%] of 3202 fever episodes in children under 6 years of age were treated promptly by mothers with the pre‐packaged drugs made available by the study. A total of 59% of children receiving PPAM were reported to have received the drugs over the prescribed 3‐day period, while 52% received the correct age‐specific dose. PPAM use was similar among literate (61%) and non‐literate mothers (55%) (P = 0.08). The overall reported risk of developing severe malaria was 8%. This risk was lower in children treated with PPAM (5%) than in children not treated with PPAM (11%) (risk ratio = 0.47; 95% CI 0.37, 0.60; P < 0.0001). This estimate of the impact of PPAM was largely unchanged when account was taken of potential confounding by age, sex, maternal literacy status, year or village. Our findings support the view that, after appropriate training and with adequately packaged drugs made available, mothers can recognize and treat promptly and correctly malarial episodes in their children and, by doing so, reduce the incidence of severe disease.
Tropical Medicine and International Health - Tập 8 Số 2 - Trang 133-139 - 2003
Child malaria treatment practices among mothers in the district of Yanfolila, Sikasso region, Mali Summary We studied child malaria treatment practices among mothers living in the District of Yanfolila in southern Mali. For sampling, we first chose five of 13 health areas with probability proportional to size. Then villages, compounds and mothers with at least one child aged 1–5 years were randomly chosen. We assessed the spleen size of one 1–5 year‐old child of each mother, collected a thick blood film and recorded the body temperature of every child whose mother thought he/she was sick. 399 mothers in 28 villages were interviewed with a structured questionnaire divided into two parts. If the child had had soumaya (a term previously associated with uncomplicated malaria) during the past rainy season, we asked about signs and symptoms, health‐seeking behaviour (who the mother consulted first) and treatment. If not, information about knowledge of the disease and treatment to be given was collected. 86% of the mothers interviewed stated that their child had been sick and almost half of them had had soumaya . All mothers named at least one sign by which they recognized the disease. Vomiting, fever and dark urine/yellow eyes/jaundice were the three most common signs mentioned. 75.8% managed their child's disease at home and used both traditional and modern treatment. The most common anti‐malarial drug was chloroquine, often given at inappropriate dosage. The sensitivity and specificity of the mothers' diagnosis was poor, although this might be explained by the large percentage of children who had already been treated at the time of the interview. The results of our survey call for prompt educational action for the correct treatment of uncomplicated malaria/soumaya , particularly for mothers and possibly for shopkeepers. The high spleen rate (58.1%) among randomly selected children confirms that malaria is a common disease in this area. Improved case‐management at home could only be beneficial.
Tropical Medicine and International Health - Tập 5 Số 12 - Trang 876-881 - 2000
Epidemiology and geography of <i>Schistosoma mansoni</i> in Uganda: implications for planning control Summary Intestinal schistosomiasis caused by infection with Schistosoma mansoni is a widespread public health problem in Uganda. Although long known to be endemic, its current distribution within the country requires updating of parasitological data to help guide planned control. We report such data collected between 1998 and 2002 from 201 schools and 68 communities across Uganda. In accordance with epidemiological expectation, prevalence and intensity increased with age, peaking at 10–20 years and thereafter declined moderately with age, whereas intensity declined more rapidly with age, and the prevalence of infection in a school was non‐linearly related to the mean intensity of infection. We used geographical information systems to map the distribution of infection and to overlay parasitological data with interpolated environmental surfaces. The derived maps indicate both a widespread occurrence of infection and a marked variability in infection prevalence, with prevalence typically highest near the lakeshore and along large rivers. No transmission occurred at altitudes >1400 m or where total annual rainfall was <900 mm; limits which can help estimate the population at risk of schistosomiasis. The results are discussed in reference to the ecology of infection and provide an epidemiological framework for the design and implementation of control efforts underway in Uganda.
Tropical Medicine and International Health - Tập 9 Số 3 - Trang 372-380 - 2004
Atypical manifestations of dengue Summary As the spread of dengue and dengue haemorrhagic fever is increasing, atypical manifestations are also on the rise, although they may be under reported because of lack of awareness. This review compiles descriptions of atypical manifestations of dengue, such as dengue encephalitis, dengue myocarditis, dengue hepatitis and dengue cholecystitis.
Tropical Medicine and International Health - Tập 12 Số 9 - Trang 1087-1095 - 2007
Environmental control of schistosomiasis through community participation in a Moroccan oasis Summary Akka oasis, in the province of Tata, southern Morocco, is one of the oldest foci of urinary schistosomiasis in Morocco where transmission is still taking place. We report the results of two studies: a cross‐sectional snail survey investigated the distribution of Bulinus truncatus in relation to habitat factors in the Akka traditional irrigation system. The presence of aquatic vegetation, especially Potamogeton sp. was identified as a key factor determining snail occurrence and abundance in canals, impoundments and isolated small puddles and streamlets in the Akka riverbed. In a participatory rapid appraisal, the community identified snail control as a way to reduce transmission of schistosomiasis. Without any further outside incentives, the local irrigation committee implemented repeated cleaning and vegetation removal in canals. A longitudinal study evaluated the effect of these measures on populations of B. truncatus . Snail and egg mass densities showed significant reductions after repeated vegetation clearing in the study sites. The participatory approach led to low‐cost, environment‐friendly schistosomiasis control measures that were effective and sustainable.
Tropical Medicine and International Health - Tập 9 Số 9 - Trang 997-1004 - 2004
Association between socio economic status and schistosomiasis infection in Jinja District, Uganda Summary Objective To examine the role of socioeconomic situation in influencing the risk and intensity of infection with Schistosomiasis mansoni .Methods Cross‐sectional study in Walukuba Division bordering Lake Victoria, Jinja District. We assessed a random sample of 463 individuals aged 10–20 years for Schistosoma mansoni infection, water contact behaviour and treatment status with praziquantel as of the last mass treatment. Socioeconomic conditions of the participants’ households were assessed by calculating a wealth index (based on type of housing and ownership of assets). Households were classified in four classes; multivariate logistic regression analysis was used to identify independent predictors of being infected with schistosomiasis. Intensities of infection with S. mansoni were compared across the classes of wealth index.Results Wealth index emerged a risk factor for infection with S. mansoni after controlling for water contact and treatment with praziquantel. The adjusted odds ratio of being infected for the lowest level of wealth index compared to the highest was 10.42 (95% CI 3.38–32.36 P < 0.001). The intensity of infection decreased with wealth index Linearity F ‐ratio 13.91, 1 df, P < 0.001). The geometric egg count for those in the lowest wealth index was 230 (95% CI 199–279) compared to 114 (95% CI 80–162) for the highest wealth index.Conclusions In addition to mass treatment with praziquantel, improving the socio‐economic conditions of the population should be given priority.
Tropical Medicine and International Health - Tập 14 Số 6 - Trang 612-619 - 2009
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