Patrick Van der Stuyft

Recurrence in tuberculosis: relapse or reinfection?

The importance of reinfection as a cause for recurrence of tuberculosis is unclear and has potential public-health implications. We systematically searched published material for studies using DNA fingerprinting to provide data on the issue. Very few studies were designed for that particular research objective and/or report on a sufficient number of observations. Differences in methods--eg, case-definitions--seriously hamper comparisons between studies. The proportion of recurrences due to reinfection ranged between 0% and 100%; however, this figure cannot be a useful indicator since the two causes of recurrence--relapse and reinfection--are essentially independent. Only one study provides an estimate of the incidence of recurrence due to reinfection, indicating its importance for HIV-infected patients in an environment with an unusually high tuberculosis incidence. We argue that apart from extreme situations like this one the problem of recurrence of tuberculosis due to reinfection has few implications for tuberculosis-control programmes.

Likelihood ratios: A real improvement for clinical decision making?

The concept of likelihood ratio has been advocated for several years as one of the better means to evaluate diagnostic tests and as a practical and valuable tool in clinical decision making. In this paper we review the basic concepts underlying the evaluation of diagnostic tests and we explore the properties and usefulness of both positive and negative likelihood ratios compared with sensitivity and specificity. Particular attention is given to the use of likelihood ratios in the clinical setting. Likelihood ratios have three main advantages: they are intuitive, they simplify the predictive value calculation and the overall evaluation of sequential testing. Disadvantages are the non-linearity and the necessity to recalculate probabilities in odds. Although they summarize the information contained in sensitivity and specificity, these characteristics are still necessary for certain clinical decisions. Since likelihood ratios have been promoted among physicians and medical students, we discuss examples of inappropriate use and misunderstandings in the medical literature: the frequent omission of confidence intervals, the choice of cut-off points based on likelihood ratios for positive test results only and the confusion between likelihood ratios for ranges and those for cut-off points.

Ebola haemorrhagic fever outbreak in Masindi District, Uganda: outbreak description and lessons learned

BackgroundEbola haemorrhagic fever (EHF) is infamous for its high case-fatality proportion (CFP) and the ease with which it spreads among contacts of the diseased. We describe the course of the EHF outbreak in Masindi, Uganda, in the year 2000, and report on response activities.MethodsWe analysed surveillance records, hospital statistics, and our own observations during response activities. We used Fishers exact tests for differences in proportions, t-tests for differences in means, and logistic regression for multivariable analysis.ResultsThe response to the outbreak consisted of surveillance, case management, logistics and public mobilisation. Twenty-six EHF cases (24 laboratory confirmed, two probable) occurred between October 21st and December 22nd, 2000. CFP was 69% (18/26). Nosocomial transmission to the index case occurred in Lacor hospital in Gulu, outside the Ebola ward. After returning home to Masindi district the index case became the origin of a transmission chain within her own extended family (18 further cases), from index family members to health care workers (HCWs, 6 cases), and from HCWs to their household contacts (1 case). Five out of six occupational cases of EHF in HCWs occurred after the introduction of barrier nursing, probably due to breaches of barrier nursing principles. CFP was initially very high (76%) but decreased (20%) due to better case management after reinforcing the response team. The mobilisation of the community for the response efforts was challenging at the beginning, when fear, panic and mistrust had to be countered by the response team.ConclusionsLarge scale transmission in the community beyond the index family was prevented by early case identification and isolation as well as quarantine imposed by the community. The high number of occupational EHF after implementing barrier nursing points at the need to strengthen training and supervision of local HCWs. The difference in CFP before and after reinforcing the response team together with observations on the ward suggest a critical role for intensive supportive treatment. Collecting high quality clinical data is a priority for future outbreaks in order to identify the best possible FHF treatment regime under field conditions.

Aedes aegypti larval indices and risk for dengue epidemics.

Entomologic indices can identify areas at high risk for disease transmission.

Community health insurance in Uganda: Why does enrolment remain low? A view from beneath

Community Health Insurance (CHI) in Uganda faces low enrolment despite interest by the Ugandan health sector to have CHI as an elaborate health sector financing mechanism. User fees have been abolished in all government facilities and CHI in Uganda is limited to the private not for profit sub-sector, mainly church-related rural hospitals. In this study, the reasons for the low enrolment are investigated in two different models of CHI. Focus group discussions and in-depth interviews were carried out with members and non-members of CHI schemes in order to acquire more insight and understanding in peoples perception of CHI, in their reasons for joining and not joining and in the possibilities they see to increase enrolment. This study, which is unprecedented in East Africa, clearly points to a mixed understanding on the basic principles of CHI and on the routine functioning of the schemes. The lack of good information is mentioned by many. Problems in ability to pay the premium, poor quality of health care, the rigid design in terms of enrolment requirements and problems of trust are other important reasons for people not to join. Our findings are grossly in line with the results of similar studies conducted in West Africa even if a number of context-specific issues have been identified. The study provides relevant elements for the design of a national policy on CHI in Uganda and other sub-Saharan countries.

The effectiveness of active population screening and treatment for sleeping sickness control in the Democratic Republic of Congo

Background  The human African trypanosomiasis (HAT) control programme of the Democratic Republic of Congo (DRC) uses mass screening with the card agglutination test for trypanosomes (CATT). We looked at the contribution of CATT and improved parasitological confirmation to the effectiveness of screening and treatment.

The Bwamanda hospital insurance scheme: effective for whom? A study of its impact on hospital utilization patterns

The Bwamanda hospital insurance scheme in Zaire was launched in the mid-eighties and is one of the few well-established and documented initiatives in the field of district-based insurance schemes in sub-Saharan Africa. It was established that hospital utilization in Bwamanda is significantly higher among the insured population. A higher hospital utilization is however not a goal in itself: it is a positive phenomenon if it takes place for problems where the hospitals know-how and technology are needed to solve the patients problem. This paper investigates the effect of the insurance scheme on hospital utilization patterns. More specifically, the distribution of this higher utilization over the different hospital departments, as well as its spatial distribution in the entire district area are analyzed. The impact of the insurance scheme on the effectiveness, equity and efficiency of hospital utilization are discussed. The relevance and possible implications of these findings on the design of the Bwamanda insurance scheme are discussed. Finally, it is argued that the methods used in the present study contribute to a coherent framework for the evaluation of similar initiatives.

The validity of serologic tests for Trypanosoma cruzi and the effectiveness of transfusional screening strategies in a hyperendemic region

BACKGROUND: This study aims at obtaining unbiased estimates of the sensitivity and specificity of existing screening tests for Trypanosoma cruzi and at simulating the effectiveness of alternative screening strategies at different prevalence rates.

Food-aid cereals to reduce neurolathyrism related to grass-pea preparations during famine

Neurolathyrism is a spastic paraparesis that can be caused by excessive consumption of the drought-resistant grass pea (Lathyrus sativus). Devastating neurolathyrism epidemics have occurred during major famine crises in various parts of the world. We investigated in a case-control study the effects of food aid on risk of paralysis. Risk increased with consumption of boiled grass pea (adjusted odds ratio 2.78, 95% CI 1.09-7.13 with cereals; 5.22, 2.01-13.55 without cereal) and raw unripe green grass pea (1.96, 1.16-3.31; p=0.011), but not with the fermented pancake, unleavened bread, and gravy preparations. In a correlational study there was an inverse relation between the number of new cases and the amount of food-aid cereals distributed per person. During famine, cereals and nutritional information should reach people before they have grass pea as the only food.

Visceral leishmaniasis in southeastern Nepal: A cross-sectional survey on Leishmania donovani infection and its risk factors

Objective  To document the frequency of Leishmania donovani infection at community level in a highly endemic region in southeastern Nepal, and to assess socioeconomic and environmental risk factors.