Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Record morbidity in Africa from a little-understood emerging disease

04.09.2006
Borreliosis, or relapsing fever, is a disease provoked by bacteria of the genus Borrelia. Two of these are encountered in tropical Africa: Borrelia crocidurae in the Sahara and Sahel, Borrelia duttoni in East Africa. This infection causes recurrent fevers over a long period that can lead to severe meningoencephalitis and sometimes death.

The human vector of Borrelia crocidurae in West Africa is the tick Ornithodoros sonrai, which lives in burrows of small wild rodents and is therefore in close contact with them. This disease was considered rare up to the end of the 1980s when a team of IRD researchers showed that in a rural area of the Dakar region tick-borne relapsing fever was the second most frequent reason for patients’ consultation at the local dispensary.

Since 1990, the IRD launched a comprehensive research programme on this disease, first in Senegal, then in the whole of West Africa. In Senegal, the investigation showed that the tick had colonized savannah and that the disease’s expansion was closely linked with the decrease in average rainfall since the long drought began in 1970. The advance of borreliosis prompted the research team to extend their epidemiological research and study the long-term trends, by 14 years of measurement of the infection’s incidence in a rural Senegalese community which was the subject of continuous demographic and health monitoring programme run jointly by the IRD, the Pasteur Institute and the University of Dakar.

The study was conducted from 1990 to 2003 on people in Dielmo, a village in the savannah in the Sine-Saloum region of Senegal, in order to determine the frequency and describe the clinical manifestations of malaria, tick-borne relapsing fever and other fevers not linked to these two diseases. The research team lived permanently in the village so that they could visit each inhabitant daily. Medical examinations and biological tests were systematically carried where someone had a fever or other symptoms that might signal the disease. The presence of Borrelia crocidurae was also tested in people without symptoms at least once a year. All rodent burrows near houses and inner yards of concession were counted and recorded. They were searched for ticks and the latter’s infection rate by the bacterium determined. Rodents and insectivores were captured in order to study the bacterial reservoir.

... more about:
»Borrelia »Malaria »Senegal »crocidurae »relapsing

Over the period of study as a whole, an average 11 % of the population suffered from borreliosis each year, an exceptional incidence rate for a disease, whatever its cause. Only malaria, among the parasitic diseases and in any case to a lesser degree, and influenza, among viral diseases, are known to produce a comparable incidence level over such a long period. Tick-borne relapsing fever is the second cause of illness after malaria. All age groups were affected by it in the population studied.

The IRD team then conducted systematic surveys in Senegal, Mali and Mauritania in order to define the geographical distribution of the tick, determine the infection rate over the whole of its area of distribution and establish the proportion of villages affected by the disease. The results showed that the vector is present in massive numbers in these three countries in any area where average rainfall is below 750 mm. Out of 30 villages studied, 26 (87 %) were colonized by the tick which was present on average in 31 % of the burrows in the villages with a Borrelia crocidurae infection rate of 21 %. Two-thirds of the villages studied showed an exposure rate to tick-borne relapsing fever among inhabitants even higher than that of the people in Dielmo. It is in most of the rural areas of Senegal and Mali and in all parts of Mauritania that the disease is a major public health problem.

Paradoxically, this emerging disease is still completely misunderstood by health care personnel, although it has become one of the most frequent bacterial infections. Laboratory testing for determining the cause of a disease is rarely possible in tropical Africa, particularly in the rural areas. Borrelia crocidurae can be detected in blood samples only during peaks of fever. Its density is usually very low and diagnosis requires the skills of an experienced microscopist. The symptoms of the disease are exactly similar to those of malaria which is very frequent in the same populations. The disease is therefore systematically confused with malaria, and failure of treatment is attributed to antimalarial drugs. Furthermore, the existence of an animal reservoir and the omnipresence of rodents in rural areas makes prevention of the disease hardly feasible. However, a cheap effective treatment is possible which involves the use of antibiotics of the tetracycline family which are available in most clinics in the bush.

Marie Guillaume | alfa
Further information:
http://www.ird.fr/fr/actualites/fiches/2006/fas245.pdf

Further reports about: Borrelia Malaria Senegal crocidurae relapsing

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>