Mahmoud Abo-Shehada

An accurate estimate of Plasmodium vivax prevalence is essential for the successful implementation of malaria control and elimination programmes. Prevalence estimates both inform control strategies and are used in their evaluation. Light microscopy is the main method for detecting Plasmodium parasitaemia in the peripheral blood, but compared to molecular diagnostics, such as polymerase chain reaction (PCR), has limited sensitivity. A systematic review and meta-analysis was conducted to assess the effect of detection method on the prevalence of P. vivax and to quantify the extent to which P. vivax infections are undetected by microscopy. Embase, Medline and the Cochrane Database were searched for studies reporting prevalence by PCR and by microscopy and that contained all of the following key words: vivax, PCR, and malaria. Prevalence estimates and study meta-data were extracted systematically from each publication. Combined microscopy:PCR prevalence ratios were estimated by random effects meta-analysis. Sensitivity and specificity of microscopy were calculated using PCR as the gold standard. Of 874 studies reviewed, 40 met the criteria for inclusion contributing 54 prevalence pairs. The prevalence of P. vivax infection measured by PCR was consistently higher than the prevalence measured by microscopy with sub-patent parasitaemia. The mean prevalence of infection detected by microscopy was 67 % (95 % CI 59–73 %) lower than the prevalence detected by PCR. The detection of sub-patent parasitaemia did not vary according to the microscopy method (thick or, thick and thin smears), the PCR prevalence (as a measure of the true P. vivax prevalence), the type of blood used or DNA extraction method. Quantifying P. vivax parasitaemia by PCR rather than microscopy consistently increased prevalence estimates by a factor of 2.3. Whilst the sensitivity of microscopy can be improved by better methods, molecular methods have potential to be scaled up to improve the detection of P. vivax transmission reservoirs.

The Phlebotomus papatasi salivary protein PpSP15 was shown to protect mice against Leishmania major, suggesting that incorporation of salivary molecules in multi-component vaccines may be a viable strategy for anti-Leishmania vaccines. Here, we investigated PpSP15 predicted amino acid sequence variability and mRNA profile of P. papatasi field populations from the Middle East. In addition, predicted MHC class II T-cell epitopes were obtained and compared to areas of amino acid sequence variability within the secreted protein. The analysis of PpSP15 expression from field populations revealed significant intra- and interpopulation variation.. In spite of the variability detected for P. papatasi populations, common epitopes for MHC class II binding are still present and may potentially be used to boost the response against Le. major infections. Conserved epitopes of PpSP15 could potentially be used in the development of a salivary gland antigen-based vaccine.

Little is known about the risk factors of human brucellosis in Jordan. A case-control study was conducted involving 56 Jordanians who had been treated for brucellosis and at least 3 matched controls for each case (n = 247). Matching was for sex, age, locality (the same village) and socioeconomic standard. Univariate and multivariate logistic regression analyses were used. In all, 17 risk factors were examined related to: contact with various livestock, milk and milk product consumption, drinking-water treatment and disease awareness. Most variables were associated with brucellosis in the univariate analysis but the final logistic model included only 4: milking sheep and goats (OR 3.5), consumption of raw feta cheese made from sheep and goat milk (OR 2.8) and consumption of cows' milk (OR 0.4) and boiled feta cheese (OR 0.4). Small ruminant farmers need to be trained in safer milking practices and feta cheese making procedures.

Results differ as to whether Brucella infection during pregnancy increases a woman's risk of miscarriage. We determined the seroprevalence of BrucelIa spp. among a sample of women with miscarriage and women with no history of miscarriage in Jordan during January-July 2003. Serum samples were collected from 445 women with miscarriage and a similar number of women with no history of miscarriage, matched on age, socioeconomic status and residence. Sera were tested using the Rose Bengal plate test and complement fixation test. The true seroprevalence among women with miscarriage was 1.8% (95% CI: 0.6-3.0), while the true seroprevalence among women with no history of miscarriage was 1.0% (95% CI: 0.08-1.9). There was no significant difference between seroprevalences of Brucella spp. among women with miscarriage and those with no history of miscarriage (P= 0.6).

Background: Sand fly saliva can drive the outcome of Leishmania infection in animal models, and salivary components have been postulated as vaccine candidates against leishmaniasis. In the sand fly Phlebotomus papatasi, natural sugar-sources modulate the activity of proteins involved in meal digestion, and possibly influence vectorial capacity. However, only a handful of studies have assessed the variability of salivary components in sand flies, focusing on the effects of environmental factors in natural habitats. In order to better understand such interactions, we compared the expression profiles of nine P. papatasi salivary gland genes of specimens inhabiting different ecological habitats in Egypt and Jordan and throughout the sand fly season in each habitat. Results: The majority of investigated genes were up-regulated in specimens from Swaymeh late in the season, when the availability of sugar sources is reduced due to water deprivation. On the other hand, these genes were not up-regulated in specimens collected from Aswan, an irrigated area less susceptible to drought effects. Conclusion: Expression plasticity of genes involved with vectorial capacity in disease vectors may play an important epidemiological role in the establishment of diseases in natural habitats.