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Sang R.,Kenya Medical Research Institute | Kioko E.,U.S. Army | Lutomiah J.,Kenya Medical Research Institute | Warigia M.,Kenya Medical Research Institute | And 11 more authors.
American Journal of Tropical Medicine and Hygiene | Year: 2010

In December 2006, Rift Valley fever (RVF) was diagnosed in humans in Garissa Hospital, Kenya and an outbreak reported affecting 11 districts. Entomologic surveillance was performed in four districts to determine the epidemic/epizootic vectors of RVF virus (RVFV). Approximately 297,000 mosquitoes were collected, 164,626 identified to species, 72,058 sorted into 3,003 pools and tested for RVFV by reverse transcription-polymerase chain reaction. Seventy-seven pools representing 10 species tested positive for RVFV, including Aedes mcintoshi/circumluteolus (26 pools), Aedes ochraceus (23 pools), Mansonia uniformis (15 pools); Culexpoicilipes, Culex bitaeniorhynchus (3 pools each); Anopheles squamosus, Mansonia africana (2 pools each); Culex quinquefasciatus, Culex univittatus, Aedes pembaensis (1 pool each). Positive Ae. pembaensis, Cx. univittatus, and Cx. bitaeniorhynchus was a first time observation. Species composition, densities, and infection varied among districts supporting hypothesis that different mosquito species serve as epizootic/epidemic vectors of RVFV in diverse ecologies, creating a complex epidemiologic pattern in East Africa. Copyright © 2010 by The American Society of Tropical Medicine and Hygiene.

Hanafi H.A.,Us Naval Medical Research Unit Number Three | El-Din E.S.M.N.,Us Naval Medical Research Unit Number Three | El-Hossary S.S.I.,Us Naval Medical Research Unit Number Three | Kaldas R.M.,Us Naval Medical Research Unit Number Three | And 3 more authors.
Acta Tropica | Year: 2013

We report experimental infection and transmission of Leishmania tropica (Wright), by the blood-feeding sand fly Phlebotomus duboscqi (Neveu-Lemaire). Groups of laboratory-reared female sand flies that fed "naturally" on L. tropica-infected hamsters, or artificially, via membrane feeding device, on a suspension of L. tropica amastigotes, were dissected at progressive time points post-feeding. Acquisition, retention and development of L. tropica through procyclic, nectomonad, and leptomonad stages to the infective metacyclic promastigote stage, and anterior progression of the parasites from abdominal midgut bloodmeal to the thoracic midgut were demonstrated in both groups. Membrane feeding on the concentrated amastigote suspension led to metacyclic promastigote infections in 60% of sand flies, whereas only 3% of P. duboscqi that fed naturally on an infected hamster developed metacyclics. Sand flies from both groups re-fed on naïve hamsters, but despite infections in 25-50% of membrane-fed and 2-3.5% of naturally fed flies, no skin lesions developed in the hamsters. After four months of observation these animals were euthanized and necropsied. Screening of the organs and tissue by polymerase chain reaction (PCR) that targeted the small subunit RNA gene, amplified generic Leishmania DNA from liver, spleen, bone marrow, and blood, but only from hamsters bitten by membrane-infected P. duboscqi. These results are notable in demonstrating the ability of P. duboscqi, originating from Kenya, to acquire, retain, develop, and transmit a Turkish strain of L. tropica originally isolated from a human case of cutaneous leishmaniasis. This marks the first demonstration of complete development and transmission of L. tropica by a member of the Phlebotomus subgenus of sand flies. © 2012.

Hanafi H.A.,Us Naval Medical Research Unit Number Three | Fryauff D.J.,Us Naval Medical Research Unit Number Three | Saad M.D.,Us Naval Medical Research Unit Number Three | Soliman A.K.,Us Naval Medical Research Unit Number Three | And 5 more authors.
Acta Tropica | Year: 2011

In June, 2003, Egypt's hospital-based electronic disease surveillance system began to record increased cases of acute febrile illness from governorates in the Nile Delta. In response to a request for assistance from the Egyptian Ministry of Health and the World Health Organization (WHO), the U.S. Naval Medical Research Unit No. 3 (NAMRU-3) provided assistance in identifying the cause and extent of this outbreak. Testing of human clinical samples (n= 375) from nine governorates in Egypt identified 29 cases of RVF viremia that spanned the period of June to October, and a particular focus of disease in Kafr el Sheikh governorate (7.7% RVF infection rate). Veterinary samples (n= 101) collected during this time in Kafr el Sheikh and screened by immunoassay for RVFV-specific IgM identified probable recent infections in cattle (10.4%) and sheep (5%). Entomologic investigations that focused in rural, rice growing villages in the Sidi Salim District of Kafr el Sheikh during August-September, 2003, collected, identified, and tested host-seeking female mosquitoes for the presence of pathogenic viruses. Three isolates of RVF virus (RVFV) were obtained from 297 tested pools of female mosquitoes and all three RVFV isolates came from Cx. antennatus (Becker). While Cx. pipiens has been considered the primary vector of RVF virus in Egypt and is often the most common man-biting species found, Cx. antennatus was the dominant species captured at the 2003 outbreak location in Kafr el Sheikh governorate. This is the first time that Cx. antennatus has been found naturally infected with RVFV in Egypt. © 2011.

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