The 1901 uganda sleeping sickness epidemic revisited: a case of mistaken identity?

The great sleeping sickness epidemic that occurred in Busoga at the turn of the century was caused by a trypanosome identified by Bruce as Trypanosoma gambiense. A study of trypanosomes from the recent epidemic in southeast Uganda has shed new light on the origins of the disease in Busoga. Thorsten Koerner, Peter de Raadt and Ian Maudlin suggest that the epidemic of the turn of the century was of T. p. rhodesiense sleeping sickness, brought about then, as now by social upheaval.

The burden of tropical diseases.

More than half the world's population is at risk of the tropical diseases malaria, leprosy, schistosomiasis, lymphatic filariasis, onchocerciasis, Chagas disease, African trypanosomiasis and leishmaniasis, and half a billion people are infected with at least one of these diseases. We present statistic on the population at risk and the infected population, and on the major morbidity and mortality attributable to each of these diseases. During the next decade the prevalence of leprosy, Chagas disease, and onchocerciasis is expected to fall, but for the other tropical diseases the epidemiological situation may remain stagnant or even worsen.

Laboratory diagnosis of trypanosomiasis.

Although African trypanosomiasis, or sleeping sickness, in humans was largely under control approximately 30 years ago, today most of the historical foci show an alarming increase in the number of cases, particularly those in East and Central Africa. This article describes the epidemiology, clinical features, and diagnostic techniques for both African and American trypanosomiasis.

[Evaluation of Testryp CATT applied to blood samples on filter paper and on diluted blood in a focus of trypanosomiasis due to Trypanosoma brucei gambiense in the Ivory Coast]. / Evaluation du Testryp CATT appliqué au sang prélevé sur papier filtre et au sang dilué, dans le foyer de trypanosomiase à Trypanosoma brucei gambiense en Côte d'Ivoire.

The Testryp CATT was performed on dried blood samples on filter-paper and on diluted blood using a microtechnique. This method was applied to both sample collection techniques and was evaluated in parallel with the classical Testryp CATT on whole blood, as described in the instructions provided with the reagents by the manufacturer. A total of 2087 people were tested; 453 samples were tested in the laboratory and 1634 during a field survey in 5 villages of a trypanosomiasis focus in Daloa, Côte d'Ivoire. This study has demonstrated that the Testryp CATT micromethod on either type of sample collection gives results comparable to the Testryp CATT on whole blood. The collection of dried blood samples on filter-paper can be performed by non-specialized staff in trypanosomiasis control programmes of the national health services. In addition, a flask of CATT reagent will allow testing of 6 times more people by the micromethod than by the classical whole-blood method. The micromethod is suitable in the implementation of programmes for the serological surveillance of populations at risk.

Parasitic diseases and urban development.

The distribution and epidemiology of parasitic diseases in both urban and periurban areas of endemic countries have been changing as development progresses. The following different scenarios involving Chagas disease, lymphatic filariasis, leishmaniasis and schistosomiasis are discussed: (1) infected persons entering nonendemic urban areas without vectors; (2) infected persons entering nonendemic urban areas with vectors; (3) infected persons entering endemic urban areas; (4) non-infected persons entering endemic urban areas; (5) urbanization or domestication of natural zoonotic foci; and (6) vectors entering nonendemic urban areas. Cultural and social habits from the rural areas, such as type of house construction and domestic water usage, are adopted by migrants to urban areas and increase the risk of disease transmission which adversely affects employment in urban populations. As the urban health services must deal with the rise in parasitic diseases, appropriate control strategies for the urban setting must be developed and implemented.

Human African trypanosomiasis: use of double centrifugation of cerebrospinal fluid to detect trypanosomes.

A double-centrifugation technique for the detection of trypanosomes in samples of cerebrospinal fluid is described and evaluated. The results of the analysis of samples of cerebrospinal fluid from 128 patients with Trypanosoma brucei gambiense sleeping sickness from the Daloa area of Côte d'Ivoire, obtained using single centrifugation, are compared with those obtained using the new method. Double centrifugation is at least twice as sensitive as single centrifugation and results in an increase of 37% in the early detection of late-stage case of the disease. The technique is easily implemented under field conditions.

Treatment of human late stage gambiense trypanosomiasis with alpha-difluoromethylornithine (eflornithine): efficacy and tolerance in 14 cases in Côte d'Ivoire.

alpha-Difluoromethylornithine (DFMO; eflornithine), an inhibitor of polyamine biosynthesis, was used to treat 14 patients with late stage gambiense sleeping sickness, 12 cases having been previously treated with and considered refractory to melarsoprol. alpha-Difluoromethylornithine was administered intravenously at a dose of 400 mg/kg/day for 14 days followed by oral treatment, 300 mg/kg/day, for 21-28 days. In all patients treatment was associated with rapid disappearance of trypanosomes from body fluids (in several cases within 24 hr) and decreased cerebrospinal fluid white blood cell counts. In all but one patient, who died of a pulmonary infection during treatment, alpha-difluoromethylornithine produced a dramatic reversal of clinical signs and symptoms of the disease. Determination of drug concentrations in serum and cerebrospinal fluid of 5 patients demonstrated that alpha-difluoromethylornithine diffuses into the central nervous system with cerebrospinal fluid levels representing up to 51% of corresponding serum concentrations. Diarrhea, abdominal pain, and anemia were the most frequent side effects associated with therapy, but were reversible and did not necessitate discontinuation of treatment. Four patients have been followed for more than 2 years post-treatment without evidence of relapse.

[Congenital trypanosomiasis and leishmaniasis]. / Trypanosomoses et leishmanioses congénitales.

Trypanosomas and leishmanias can cross the placenta. Trypanosoma cruzi (American trypanosomiasis or Chagas' disease) may infect the placenta, with or without fetal transmission (congenital trypanosomiasis). Congenital transmission of Chagas' disease is a real problem of public health. Risk of congenital infections is less important for African trypanosomiasis and leishmaniasis. However, physicians should always think of this diagnosis in individual cases, since these diseases may occur in any part of the world, including outside the endemic areas.

A field comparison of seven diagnostic techniques for human trypanosomiasis in the Luangwa Valley, Zambia.

One serological and six parasitological techniques for diagnosing human trypanosomiasis were compared with regard to sensitivity, specificity, positive and negative predictive values, and practicality in field application in the Luangwa Valley of Zambia. Seven (0.64%) trypanosomiasis cases were diagnosed parasitologically in a survey of 1093 people from 19 villages. The indirect fluorescent antibody test (IFAT) was more sensitive but less specific than the parasitological techniques, detecting 71% of the confirmed cases in the first round of testing. Rat inoculation, the Giemsa stained thick film and miniature anion-exchange/centrifugation (mAEC) were all more sensitive than wet blood film examination, microhaematocrit centrifugation and wet film examination of the buffy coat after microhaematocrit centrifugation. The comparison indicated that the most effective, practical combination of techniques for survey in the Luangwa Valley was IFAT screening followed by examination of seropositive patients by rat inoculation and the mAEC (or stained thick film) in parallel format. Calculation of positive and negative predictive values showed that trypanosomiasis point prevalence measured in this way would still be underestimated by approximately 60%, indicating the need to improve IFAT specificity and parasitological sensitivity. Although only one of the seven patients diagnosed in the survey presented with signs and symptoms indicating possible trypanosomiasis, no evidence of a population of "healthy carriers" was found.