FRANKFURT. An infection with Chagas disease is only
possible in Latin America since the insect species that spread the disease only
occur there. Scientists at 51猎奇 and the Senckenberg Society for
Natural Research have now used ecological niche models to calculate the extent
to which habitats outside of the Americas may also be suitable for the bugs.
The result: climatically suitable conditions can be found in southern Europe
for two kissing bug species; along the coasts of Africa and Southeast Asia the
conditions are suitable for yet another species. The Frankfurt scientists therefore
call for careful monitoring of the current distribution of triatomine bugs.
(eLife DOI: 10.7554/eLife.52072)
The acute phase of the tropical Chagas disease
(American Trypanosomiasis) is usually symptom-free: only in every third case
does the infecting parasite (Trypanosoma
cruzi) cause any symptoms at all, and these are often unspecific, such as
fever, hives and swollen lymph glands. But the parasites remain in the
body, and many years later chronic
Chagas disease can become life-threatening with pathological enlargement of the
heart and progressive paralysis of the gastrointestinal tract. There is no
vaccine for Chagas disease. The WHO estimates that 6 to 7 million people are
infected worldwide, with the majority living in Latin America (about 4.6
million), followed by the USA with more than 300,000 and Europe with approximately
80,000 infected people.
Chagas parasites are transmitted by
predatory blood-sucking bugs that ingest the pathogen along with the blood. After a
development period in the intestinal tract of the bugs, the parasites are shed
in the bug's faeces. The highly infectious faeces are unintentionally rubbed
into the wound by the extreme itching caused by the bug bite. Oral transmission
by eating food contaminated with triatomine
bug faeces is also possible.
Researchers led by the Frankfurt
parasitologists and infection biologists Fanny Eberhard and Professor Sven
Klimpel have used niche models to investigate which climatic conditions in the
world are suitable for Latin American kissing bugs. In particular, temperature
and precipitation patterns were incorporated into the calculations on the
climatic suitability of a region. The researchers were able to show that currently
in addition to Latin America, Central Africa and Southeast Asia also have
suitable habitats for triatomines. Two of the triatomine species, Triatoma sordida and Triatoma infestans, are now finding
suitable habitats in temperate regions of southern Europe such as Portugal,
Spain, France and Italy. Both triatomine species frequently transmit the
dangerous parasites in Latin America and can be found inside or near houses and
stables, where they get their nightly blood meals preferably from dogs,
chickens and humans.
Another triatomine species, Triatoma rubrofasciata, has already been
detected outside Latin America. The model calculations by the Frankfurt
scientists identify suitable habitats along large areas of the African and
Southeast Asian coasts.
Professor Sven Kimpel explains: 鈥淭here are
people living in Europe who were infected with Chagas in Latin America and are unknowingly
carriers of Trypanosoma cruzi. However, the parasite can
currently only be transmitted to other people through untested blood preservations
or by a mother to her unborn child. Otherwise, Trypanosoma cruzi
requires triatomine bugs as intermediate hosts. And these bugs are increasingly
finding suitable climatic conditions outside Latin America. Based on our data,
monitoring programmes on the distribution and spreading of triatomine bugs would therefore be feasible. Mandatory
reporting of Chagas disease cases could also be helpful."
Publication: Fanny E. Eberhard, Sarah
Cunze, Judith Kochmann, Sven Klimpel. Modelling the
climatic suitability of Chagas disease vectors on a global scale. eLife
2020;9:e52072 doi: 10.7554/eLife.52072,
An image may be downloaded here:
Caption:
The triatomine or 鈥渒issing" bug Triatoma infestans. Credit: Dorian D.
D枚rge for 51猎奇 Frankfurt
Further information:
Prof.
Dr. Sven Klimpel
Institute for Ecology, Evolution and
Diversity, 51猎奇
& Senckenberg Biodiversity and Climate
Research Centre
Tel.
+49 69 798 42237
E-Mail:
Klimpel@bio.uni-frankfurt.de
