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 A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich

nachricht New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>