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Biomedical subjects

D M Watts

Publications and source records attributed to D M Watts.

107 records · Page 6Linked to original sources
PubMed1975

Transovarial transmission of arboviruses by mosquitoes: a review.

One interesting aspect of mosquito-borne arboviruses is their endemic persistence, espeically during adverse climatic conditions in the temperate zones. The hypothesis that transovarial transmission of alpha- and flaviviruses by their respective mosquito vectors could serve as an overwintering mechanism has been proposed; however, experimental data in support of this hypothesis are not very convincing. Recently, some of the California encephalitis group arboviruses have been shown to be transmitted transovarially by Aedes species mosquitoes, and studies indicate that this mechanism contributes to the natural maintenance cycle of these viruses. Finally, consideration is given to the possibility that transovarial transmission may be unique to the California encephalitis group arboviruses and may be related to their association with a vector that overwinters in the egg stage of its life cycle.

Aedes↗
PubMed1973

Transovarial transmission of LaCrosse virus (California encephalitis group) in the mosquito, Aedes triseriatus.

LaCrosse virus (California encephalitis group) was recovered from F(1) eggs, larvae, and adults produced by experimentally infected Aedes triseriatus. The F(1) females transmitted the virus by bite to suckling mice and chipmunks. This, plus isolations of LaCrosse virus from larvae collected from their natural habitats in enzootic areas and from males and females reared from them, suggests that transovarial transmission is the overwintering mechanism for this arbovirus in northern United States.

Aedes↗
PubMedDate not supplied

The prevalence of arboviral, rickettsial, and Hantaan-like viral antibody among schoolchildren in the Nile river delta of Egypt.

A serosurvey was conducted during October and November 1989 to estimate the prevalence of selected arboviral, rickettsial, and Hantaan viral antibody among a sample of schoolchildren from 4 villages in the Bilbeis area of the Nile river delta, Egypt. Blood specimens were obtained from subjects aged 8 to 14 years. Enzyme immunoassay testing of the sera indicated that the prevalence of antibody was 9% (21/223) for Sicilian sandfly fever, 4% (8/223) for Rift Valley fever, 3% (15/437) for West Nile virus and 9% (28/315) for Hantaan (HTN) virus. Antibody was demonstrated among 22% (93/418) of the same study subjects against Coxiella burnetti, 53% (199/373) against Rickettsia typhi, and 37% (137/371) against R. conorii.

Adolescent↗
PubMedDate not supplied

Low risk of sexual transmission of hepatitis C virus in Somalia.

The prevalence in Somalia of antibody to hepatitis C virus (anti-HCV) was determined in a survey of 236 female prostitutes, 80 sexually transmitted disease (STD) clinic patients, 79 male soldiers, and 43 tuberculosis patients. Of 98 (22%) serum samples repeatedly anti-HCV reactive by first and second generation enzyme-linked immunosorbent assay kits, only 8 (1.8%) were anti-HCV positive by immunoblot assay (RIBA-2). Anti-HCV seropositivity by immunoblot assay was not associated with any risk group or with positive syphilis serology (found in 18% of subjects) or antibody to human immunodeficiency virus 1 (in 1.4% of subjects). These data indicate that sexual transmission of hepatitis C virus is not common in Somalia among sexually active populations, including female prostitutes and other groups at high risk of STDs and the acquired immune deficiency syndrome.

Adolescent↗
PubMedDate not supplied

Notes on the phlebotomine sand flies from the Peruvian southeast--I. Description of Lutzomyia (Helcocyrtomyia) adamsi n. sp. (Diptera: Psychodidae).

A new species of phlebotomine sand fly, Lutzomyia adamsi n. sp., is described and illustrated from specimens collected during August 1994, in Sandia, Department of Puno-Peru. According to the Oficina Nacional de Evaluacion de Recursos Naturales(ONERN 1976), this locality is situated in the life zone known as humid, mountain, low tropical forest (bh-MBT). Many areas in the northern part of Puno, mainly in the Inambari and Tambopata basins, are endemic to leishmaniasis. These areas are the continuation of others, largely known as "leishmaniasic" in the departments of Cusco and Madre de Dios. The morphological characteristics indicated that this species belongs to the genus Lutzomyia, subgenus Helcocyrtomyia Barretto, 1962.

Animals↗
PubMedDate not supplied

An outbreak of fulminant hepatitis delta in the Waorani, an indigenous people of the Amazon basin of Ecuador.

An outbreak of delta hepatitis occurred during 1998 among the Waorani of the Amazon basin of Ecuador. Among 58 people identified with jaundice, 79% lived in four of 22 Waorani communities. Serum hepatitis B surface antigen (HBsAg) was found in the sera of 54% of the jaundiced persons, and 14% of asymptomatic persons. Ninety-five percent of 105 asymptomatic Waorani had hepatitis B core (HBc) IgG antibody, versus 98% of 51 with jaundice. These data confirm that hepatitis B virus (HBV) infection is highly endemic among the Waorani. Sixteen of 23 (70%) HBsAg carriers identified at the onset of the epidemic had serologic markers for hepatitis D virus (HDV) infection. All 16 were jaundiced, where as only two of seven (29%) with negative HDV serology were jaundiced (P = .0006). The delta cases clustered in families, 69% were children and most involved superinfection of people chronically infected with HBV. The data suggest that HDV spread rapidly by a horizontal mode of transmission other than by the sexual route.

Adolescent↗
PubMedDate not supplied

Trocara virus: a newly recognized Alphavirus (Togaviridae) isolated from mosquitoes in the Amazon Basin.

This report describes Trocara virus, a newly recognized member of the genus Alphavirus, that has been isolated from Aedes serratus mosquitoes collected at two widely separated sites in the Amazon Basin. Biological, antigenic and genetic characteristics of the new virus are given. Results of these studies indicate that Trocara virus is the first member of a newly discovered antigenic complex within the family Togaviridae genus Alphavirus. The public health and veterinary importance of Trocara virus is still unknown.

Aedes↗
PubMedDate not supplied

Hepatitis C in Peru: risk factors for infection, potential iatrogenic transmission, and genotype distribution.

A large seroepidemiologic and genotyping study of hepatitis C virus (HCV) was conducted in Lima, Peru, during the periods of 1986 to 1993 (cohort A) and 1994 (cohort B). Anti-HCV seroprevalence rates were 15.6% (216 of 1,389) and 11.7% (168 of 1,438), respectively. Low rates were seen among volunteer blood donors (1.1% and 0.8%). Anti-HCV rates were much higher among patients undergoing hemodialysis (43.7% and 59.3%), hemophiliacs (60.0% and 83.3%), in those more than 39 years old (18.2% and 26.0%), in females (25.0% and 27.4%), and in less-educated persons (16.9%). Age- and gender-adjusted risk factors in cohort B included blood transfusion history (adjusted odds ratio [AOR] = 29.8), prior organ transplantation (AOR = 9.1) or a history of hepatitis (AOR = 4.9), previous hospitalization (AOR = 3.7), a history of intravenous drug use (AOR = 3.5), prior major surgery (AOR = 2.6), a history of acupuncture (AOR = 2.1), previous dental procedures (AOR = 1.2), and prior medical injections (AOR = 1.04). The most prevalent HCV genotype was type 1 (86%), followed by type 3 (10%) and type 2 (2%). Transmission through unsafe injection-related and medical/dental procedures appears to play an important role in HCV infection among Peruvians.

Adolescent↗
PubMedDate not supplied

Detection of pathogenic Leptospira spp. infections among mammals captured in the Peruvian Amazon basin region.

To identify potential zoonotic reservoirs of pathogenic leptospires in the Peruvian Amazon basin, wild mammals were trapped from July 1997 to December 1998 near the city of Iquitos. After extraction of nucleic acids from animal kidneys, DNA of pathogenic leptospires was identified by polymerase chain reaction (PCR) assays using one of two primer sets, one amplifying a region of the 23S rRNA gene, and the other amplifying a gene fragment specific for Leptospira spp (G1/G2 primers). Overall, 29% (40 of 136) of the mammals tested showed evidence of renal infection by Leptospira spp., including 20% (13 of 64) of the rodents, 39% (20 of 51) of the marsupials, and 35% (7 of 20) of the chiropterans (bats). Marsupials and chiropterans were implicated as more significant reservoir hosts of leptospires pathogenic to humans than previously recognized.

Animals↗