Ghazi A. Jamjoom

Brucellosis in Riyadh, Saudi Arabia. A microbiological and clinical study

During a period of two years, 30 cases of brucellosis were positively diagnosed from a total of 209 patients who reported with prolonged fever for investigation. Diagnosis was made both by blood culture and serological tests. The latter included slide and tube agglutination in all cases and an enzyme linked immunosorbent assay (ELISA) in 16. 11 cases (36.7%) gave negative results by the slide-agglutination screening test used at the recommended single serum dilution of 1:80. This was due to the prozone phenomenon as they gave positive results upon further dilution in the tube agglutination test. 13 of the 16 tested by ELISA were positive for both IgM and IgG and three were positive for IgG only. Of the six cases that were positive by culture, five grew Brucella melitensis and one B. abortus.

Seroepidemiology of Asymptomatic Dengue Virus Infection in Jeddah, Saudi Arabia

Background Although virologically confirmed dengue fever has been recognized in Jeddah, Saudi Arabia, since 1994, causing yearly outbreaks, no proper seroepidemiologic studies on dengue virus have been conducted in this region. Such studies can define the extent of infection by this virus and estimate the proportion that may result in disease. The aim of this study was to measure the seroprevalence of past dengue virus infection in healthy Saudi nationals from different areas in the city of Jeddah and to investigate demographic and environmental factors that may increase exposure to infection. Methods Sera were collected from 1984 Saudi subjects attending primary health care centers in six districts of Jeddah. These included general patients of various ages seeking routine vaccinations, antenatal care or treatment of different illnesses excluding fever or suspected dengue. A number of blood donors were also tested. Serum samples were tested by enzyme immunoassay (EIA) for IgG antibodies to dengue viruses 1, 2, 3, 4. A questionnaire was completed for each patient recording various anthropometric data and factors that may indicate possible risk of exposure to mosquito bites and dengue infection. Patients with missing data and those who reported a history of dengue fever were excluded from analysis, resulting in a sample of 1939 patients to be analyzed. Results The overall prevalence of dengue virus infection as measured by anti-dengue IgG antibodies from asymptomatic residents in Jeddah was 47.8% (927/1939) and 37% (68/184) in blood donors. Infection mostly did not result in recognizable disease, as only 19 of 1956 subjects with complete information (0.1%) reported having dengue fever in the past. Anti dengue seropositivity increased with age and was higher in males than females and in residents of communal housing and multistory buildings than in villas. One of the six districts showed significant increase in exposure rate as compared to the others. Availability of public sewage was associated with lower infection at a nearly significant level. No other clear risk factors were identifiable. Infection was not related to travel abroad. Conclusions Our results indicate a relatively high exposure of Jeddah residents to infection by dengue viruses, which must be considered endemic to this region. Infection largely remained asymptomatic or was only associated with minor illness for which patients did not seek treatment. These results call for continued vigilance for clinical cases of dengue that may arise from this wide exposure. They also call for more extensive control efforts to reduce exposure to and transmission of dengue viruses.

Malaria in children - experience from Asir region, Saudi Arabia.

During a five year period, 233 cases of malaria (2.4%) were diagnosed among 9259 children with fever and hepatosplenomegaly seen in Asir Central Hospital, Abha, Saudi Arabia. The majority of these were below four years of age and came from Tihama, a hot, humid valley area in the Asir region. The infection was seasonal and occurred between December and May. Apart from fever, vomiting and hepatosplenomegaly, anemia was a common clinical finding; this was partly due to iron deficiency anemia, probably nutritional. Most of the cases responded to chloroquine therapy; however, three required intravenous quinine and two received Fansidar to effect eradication of the parasitemia. During the study, two patients died, one from cerebral malaria and the other from severe hemolytic anemia and hemoglobinuria. For prevention of malaria in this endemic area, an integrated program is advocated that includes the use of bednets impregnated with permethin, adequate treatment of proven cases and intensive health education on malaria control and nutrition.

Virological diagnosis of dengue fever in Jeddah, Saudi Arabia: Comparison between RT-PCR and virus isolation in cell culture

A total of 233 serum samples were collected from patients presenting to King Abdulaziz University Hospital with suspected cases of Dengue Fever (DF) from 2006 to 2008. Dengue virus was successfully isolated from 70 samples by culture on C6/36 and LLC-MK2 cells; it was then detected by indirect immunofluorescence assay (IFA). The cytopathic effect (CPE) of dengue virus on C6/36 appeared in most of the samples within 1-4 days post-inoculation comparing to 7-12 days on LLC-MK2 cells, and this was characterized by the ability to induce syncytia and multinucleated giant cells. On the other hand, by using RT-PCR technique, 87 (37.3%) samples were positive. All 70 (30.4%) samples with positive cell culture results were detectable by RT-PCR in addition to 17 culture-negative samples were RT-PCR positive. Dengue virus type 1 (DENV-1) was the dominant serotype followed by DENV- 3 and DENV-2, while DENV-4 was not detected in tested samples. These results indicate that DENV-RNA detection by RT-PCR is more sensitive than virus isolation. We suggest that the high sensitivity coupled with the turnaround time, have made the RT-PCR a better choice as a routine test for DENV diagnosis. Key words:

Follow-up of HIV western blot indeterminate results.

Indeterminate results obtained with the Western blot (WB) confirmatory test on HIV enzyme immunoassay (EIA)-positive samples, constituted 15.6% (444/2849) over a 2.5-year period at the referral laboratory for the Western region at the King Fahd General Hospital, Jeddah. Two hundred and fourteen WB-indeterminate samples were followed up by repeat WB testing of subsequent samples from the same patients over a 3-12 month period. One hundred and forty-two samples (66.4%) gave negative results. Sixty-five samples (30%) remained indeterminate. Only seven samples (3.3%) not initially meeting WHO criteria for positivity turned clear-cut positive, with high EIA readings on follow-up. It was discovered initally that a significant proportion of indeterminates was due to low-grade cross-contamination between samples as a result of aerosol backflow during aspiration in the washing procedure. This was eliminated by rinsing the lines between samples, separating samples with high EIA from those with low EIA, and rerunning indeterminate samples. A reduction of indeterminates from 21% to 8.5% subsequently followed. After this improvement, most of the samples that remained indeterminate had low EIA readings, and few bands of mainly anti-gag (p55, p24 or p18) or anti-pol (p51) antibodies, while the few turning positive all had anti-gp160, in addition to anti-p24 or p55. Interestingly, over the last year and a half of the study, 1.4% of the total samples (21/1506) had repeatedly high EIA readings but were negative by WB. In addition, 16 samples (1.1%) were positive for HIV-2. A separate computer-based system for the storage of data was very helpful in ascertaining proper follow-up of indeterminate WB results.

Hepatitis A and Hepatitis B in the Asir Region, Southwestern Saudi Arabia

This study was conducted to gather information on the prevalence of hepatitis A and hepatitis B in the Asir region of southwestern Saudi Arabia and to optimize the use of routine serological tests ...

Protease inhibitors as potential therapeutic agents for AIDS.

A decade since the epidemic of the acquired immunodeficiency syndrome (AIDS) was first recognized, a wealth of information has accumulated on the molecular biology of the causative agents, the human immunodeficiency viruses (HIV). Of particular interest is knowledge of the viral enzymes involved in the formation of new virus particles. Such enzymes constitute attractive targets for efforts aimed at selecting agents that interfere with virus multiplication and subsequent spread and pathogenesis. Already, several agents that inhibit the viral reverse transcriptase (e.g., nucleoside analogs such as Zidovudine) have proved to have a beneficial effect on the course off the disease, but their prolonged use has been associated with significant toxicity and the emergence of resistant mutants. A second enzyme that has recently attracted attention is the virus-coded protease. This enzyme is involved in the cleavage of viral precursor polyproteins into the final products that constitute the mature virus particle. Protease inhibitors interfere with the process of virus maturation which is required for the formation of infective virus particles. Several custom-made inhibitors with a high selective action against HIV protease have been produced recently. They are nonhydrolyzable peptide analogs that mimic the cleavage sequences of the natural substrate of the enzyme during the transition state of the cleavage reaction. It is hoped that a similar selectivity in vivo may make protease inhibitors a promising new category of AIDS therapeutics.