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22 - El Niño causes dramatic outbreak of Paederus dermatitis in East Africa
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- By Ingeborg M. C. J. van Schayk, International Centre of Insect Physiology and Ecology, Nairobi, Kenya, Ruben O. Agwanda, Kenya Medical Research Institute, Nairobi, Kenya, John I. Githure, Tulane University, New Orleans, USA, John C. Beier, Bart G. J. Knols, Wageningen University Research Centre, the Netherlands
- Edited by Pak Sum Low
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- Book:
- Climate Change and Africa
- Published online:
- 10 December 2009
- Print publication:
- 25 August 2005, pp 240-247
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Summary
Keywords
Paederus sabaeus; Nairobi Fly; outbreak; El Niño; Paederus dermatitis; conjunctivitis; Nairobi; Kenya
Abstarct
An outbreak of Paederus sabaeus rove beetles in Kenya during the 1997–1998 El Niño resulted in a dramatic increase of vesicular dermatitis in its capital Nairobi. The beetle, popularly called ‘Nairobi Fly’, contains a potent toxic fluid that causes epidermolysis and acute conjunctivitis. A cross-sectional epidemiological study involving 1, 208 Nairobi residents was conducted to determine the health impact of this outbreak. The results showed that one-third of the Nairobi population were infected during this period. The majority of the respondents reported lesions on exposed body parts above the shoulders. Disfiguring, painful blisters and skin rashes in and around the facial area had a strong personal and social impact. Policy makers and public health specialists need to recognize that outbreaks of insects of medical importance resulting from global climatic events require urgent remedial action.
INTRODUCTION
Modern human activities have an obvious negative impact on the environment and contribute to the irreversible alteration of the global climate. Evidence shows that successions of abnormal climatic events have a disturbing effect on the world's ecosystems (Epstein et al., 1998). Rise of temperatures and more frequent occurrence of extreme weather conditions alter the flora and affect the development of competitive insect species in certain parts of the world, causing unexpected insect explosions with consequences for human health (Dukes and Mooney, 1999).
Plasmodium falciparum malaria disease manifestations in humans and transmission to Anopheles gambiae: a field study in Western Kenya
- L. C. GOUAGNA, H. M. FERGUSON, B. A. OKECH, G. F. KILLEEN, E. W. KABIRU, J. C. BEIER, J. I. GITHURE, G. YAN
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- Journal:
- Parasitology / Volume 128 / Issue 3 / March 2004
- Published online by Cambridge University Press:
- 03 March 2004, pp. 235-243
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- Article
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Transmission of the malaria parasite Plasmodium is influenced by many different host, vector and parasite factors. Here we conducted a field study at Mbita, an area of endemic malaria in Western Kenya, to test whether parasite transmission to mosquitoes is influenced by the severity of malaria infection in its human host at the time when gametocytes, the transmission forms, are present in the peripheral blood. We examined the infectivity of 81 Plasmodium falciparum gametocyte carriers to mosquitoes. Of these, 21 were patients with fever and other malaria-related symptoms, and 60 were recruited among apparently healthy volunteers. Laboratory-reared Anopheles gambiae s.s. (local strain) were experimentally infected with blood from these gametocyte carriers by membrane-feeding. The severity of the clinical symptoms was greater in febrile patients. These symptomatic patients had higher asexual parasitaemia and lower gametocyte densities (P=0·05) than healthy volunteers. Ookinete development occurred in only 6 out of the 21 symptomatic patients, of which only 33·3% successfully yielded oocysts. The oocyst prevalence was only 0·6% in the 546 mosquitoes that were fed on blood from this symptomatic group, with mean oocyst intensity of 0·2 (range 0–2) oocysts per mosquito. In contrast, a higher proportion (76·7%) of healthy gametocyte carriers yielded ookinetes, generating an oocyst rate of 12% in the 1332 mosquitoes that fed on them (mean intensity of 6·3, range: 1–105 oocysts per mosquito). Statistical analysis indicated that the increased infectivity of asymptomatic gametocyte carriers was not simply due to their greater gametocyte abundance, but also to the higher level of infectivity of their gametocytes, possibly due to lower parasite mortality within mosquitoes fed on blood from healthy hosts. These results suggest that blood factors and/or conditions correlated with illness reduce P. falciparum gametocyte infectivity.