Minimal Rickettsial Infection Rates and Distribution of Ticks in Uganda: An Assessment of the Seasonal Effects and Relevance to Tick-Borne Disease Risk in East Africa.

Tick-borne diseases (TBDs) pose a significant risk to humans and represent one of the major factors influencing readiness within the United States' military worldwide. Additionally, ticks and TBDs constitute major animal health problems leading to economic losses at multiple levels affecting low- and middle-income countries the hardest. Tick control is frequently hampered by issues ranging from acaricide resistance to lack of data on tick distribution and infection rates. We conducted a cross-sectional study to assess tick species distribution, host use, and rickettsial pathogen infection rate of ticks in different areas of the Uganda Cattle Corridor. We identified 4,425 hard ticks (Ixodida: Ixodidae) comprised of seven species by morphological characters with 3,315 ticks collected from four locations during the dry season and 1,110 ticks from one location during the wet season. Rickettsial pathogen prevalence was assessed in ticks collected from two districts to determine the minimum infection rate compared across seasons, village location, and tick species. We found statistically significant differences in the abundance and distribution of tick species among districts in the dry season, host animal species, and the proportion of rickettsial positive pools between villages. Seasonality, village location, and tick species do not affect the minimum infection rate of rickettsial pathogens of ticks in Uganda, but village location affects the proportion of positive tick pools. These results indicate geographical and seasonal differences among pathogen-harboring ticks contributing to our understanding of the current distribution of ticks and TBDs in Uganda.

Low Prevalence of Leptospira Carriage in Rodents in Leptospirosis-Endemic Northeastern Thailand.

Leptospirosis is a neglected zoonotic disease affecting mostly the world's tropical regions. The rural people of northeastern Thailand suffer from a large number of leptospirosis infections, and their abundant rice fields are optimal rodent habitats. To evaluate the contribution of diversity and carriage rate of pathogenic Leptospira in rodent reservoirs to leptospirosis incidence, we surveyed rodents, between 2011 and 2012, in four provinces in northeastern Thailand with the highest incidence rates of human leptospirosis cases. We used lipL32 real-time PCR to detect pathogenic Leptospira in rodent kidneys, partial 16S rRNA gene sequencing to classify the infecting Leptospira species, and whole 16S rDNA sequencing to classify species of isolated Leptospira. Overall prevalence of Leptospira infection was 3.6% (18/495). Among infected rodents, Bandicotaindica (14.3%), Rattusexulans (3.6%), and R. rattus (3.2%) had renal carriage. We identified two pathogenic Leptospira species: L. interrogans (n = 15) and L. borgpetersenii (n = 3). In addition, an L. wolffii (LS0914U) isolate was recovered from the urine of B. indica. Leptospira infection was more prevalent in low density rodent populations, such as B. indica. In contrast, there was a lower prevalence of Leptospira infection in high density rodent populations of R. exulans and R. rattus.

Colonization and Maintenance of Anopheles belenrae and Anopheles pullus From the Republic Of Korea.

The Anopheles Hyrcanus Group in the Republic of Korea (ROK) consists of 5 morphologically indistinct species that can only be identified with certainty by polymerase chain reaction (PCR). A total of 86 bloodfed Anopheles spp. were collected from a cow barn located in the village of Tongilchon near the demilitarized zone in the ROK on June 13, 2016, and sent to the Armed Forces Research Institute of Medical Sciences in Bangkok, Thailand, where they were identified to species by PCR. The 1st shipment contained 15 An. belenrae and 37 An. pullus females that were used to start the colonies. Parent females that oviposited were identified by PCR for colonization. A higher proportion of F1-F4 females of An. belenrae than An. pullus bloodfed when provided both blood meals on human arms and using a membrane feeding system with human blood. Following blood meals, the females were forced mated for colony maintenance. The mean numbers of eggs oviposited per female for An. belenrae was 127.7 ± 19.3 and for An. pullus was 136 ± 23.6. On average, at 25°C (±2°C) An. belenrae and An. pullus took 15.1 and 16.1 days to develop from egg to adult, respectively. A 2nd group of bloodfed Anopheles spp. was collected at the same location in the ROK on June 24, 2017. This group contained 13 An. belenrae and 27 An. pullus. Similarly, eggs were obtained and adults identified by PCR and then reared to adults and subsequent generations forced mated to members of each of the existing colonies to increase genetic diversity. The colonies were established to evaluate their susceptibility to vector vivax malaria, which is essential to better understand the epidemiology of malaria transmission in Korea. This is the 1st report of colonization of both An. belenrae and An. pullus.

Sugar and Multivitamin Diet Effects on The Longevity and Mating Capacity of Laboratory-Reared Male Anopheline Mosquitoes.

Successful mating by male mosquitoes is dependent on several factors, with sugar feeding being particularly important. The effect of ingested vitamins on adult male mosquitoes is poorly understood. This laboratory study used 3 anopheline species, Anopheles campestris, An. dirus, and An. sawadwongporni, to study the effect of sugar and vitamins on male longevity, copulation, and fecundity. Males were fed 1 of 5 diets containing different combinations of sugar and vitamins: 10% glucose, 10% sucrose, 10% multivitamin syrup, 10% multivitamin syrup + 10% glucose, and 10% multivitamin syrup + 10% sucrose. The longevity of males was measured for a period of 15 days. Forced mating was used to simulate copulation, and fecundity was measured by counting the number of eggs oviposited and the hatch rate of larvae. The longevity of An. campestris and An. dirus was greatest when fed a diet of 10% multivitamin syrup + 10% glucose, and the longevity of An. sawadwongporni was greatest when fed a diet of 10% multivitamin syrup + 10% sucrose. The 1st mating routinely produced the most viable eggs when males were mated with several females. The diet of 10% multivitamin syrup + 10% sucrose produced numerically greater egg production and larval emergence for all 3 species, although this was not always statistically significant due to variability and small sample size. These results indicate that the addition of multivitamin syrup to sucrose may produce healthier and more fit male anophelines. This has potential implications for increasing insectary operations and improving the fitness of laboratory-reared male mosquitoes that will be released for mosquito and disease-pathogen control studies.

Field evaluation of diagnostic performance of malaria rapid diagnostic tests in western Kenya.

BACKGROUND: Malaria continues to be a major burden in the endemic regions of Kenya. Health outcomes associated with case management are dependent on the use of appropriate diagnostic methods. Rapid diagnostic tests (RDTs) have provided an important tool to help implement the WHO recommended parasite-based diagnosis in regions where expert microscopy is not available. One of the questions that must be answered when implementing RDTs is whether these tests are useful in a specific endemic region, as well as the most appropriate RDT to use. Data on the sensitivity and specificity of RDT test kits is important information to help guide test selection by national malaria control programmes. METHODS: This study evaluated the diagnostic performance of RDTs including First Response (FR), CareStart (CS), SD Bioline (SD), and Binax Now (BN). The performance of these malaria kits was compared to microscopy, the gold standard, for the detection of malaria parasites. The malaria RDTs were also compared to PCR which is a more sensitive reference test. Five-hundred participants were included in the study through community screening (50 %) and testing suspected malaria cases referred from health facilities. RESULTS: Of the 500 participants recruited, 33 % were malaria positive by microscopy while 51.2 % were positive by PCR. Compared to microscopy, the sensitivity of eight RDTs to detect malaria parasites was 90.3-94.8 %, the specificity was 73.3-79.3 %, the positive predictive value was 62.2-68.8 %, and the negative predictive value was 94.3-96.8 %. Compared to PCR, the sensitivity of the RDTs to detect malaria parasites was 71.1-75.4 %, the specificity was 80.3-84.4 %, the positive predictive value was 80.3-83.3 %, and the negative predictive value was 73.7-76.1 %. The RDTs had a moderate measure of agreement with both microscopy (>80.1 %) and PCR (>77.6 %) with a κ > 0.6. CONCLUSION: The performance of the evaluated RDTs using field samples was moderate; hence they can significantly improve the quality of malaria case management in endemic regions in Kenya by ensuring appropriate treatment of malaria positive individuals and avoiding indiscriminate use of anti-malarial drugs for parasite negative patients.

Characterization of Plasmodium ovale curtisi and P. ovale wallikeri in Western Kenya utilizing a novel species-specific real-time PCR assay.

BACKGROUND: Plasmodium ovale is comprised of two genetically distinct subspecies, P. ovale curtisi and P. ovale wallikeri. Although P. ovale subspecies are similar based on morphology and geographical distribution, allelic differences indicate that P. ovale curtisi and P. ovale wallikeri are genetically divergent. Additionally, potential clinical and latency duration differences between P. ovale curtisi and P. ovale wallikeri demonstrate the need for investigation into the contribution of this neglected malaria parasite to the global malaria burden. METHODS: In order to detect all P. ovale subspecies simultaneously, we developed an inclusive P. ovale-specific real-time PCR assay based on conserved regions between P. ovale curtisi and P. ovale wallikeri in the reticulocyte binding protein 2 (rbp2) gene. Additionally, we characterized the P. ovale subspecies prevalence from 22 asymptomatic malaria infections using multilocus genotyping to discriminate P. ovale curtisi and P. ovale wallikeri. RESULTS: Our P. ovale rbp2 qPCR assay validation experiments demonstrated a linear dynamic range from 6.25 rbp2 plasmid copies/microliter to 100,000 rbp2 plasmid copies/microliter and a limit of detection of 1.5 rbp2 plasmid copies/microliter. Specificity experiments showed the ability of the rbp2 qPCR assay to detect low-levels of P. ovale in the presence of additional malaria parasite species, including P. falciparum, P. vivax, and P. malariae. We identified P. ovale curtisi and P. ovale wallikeri in Western Kenya by DNA sequencing of the tryptophan-rich antigen gene, the small subunit ribosomal RNA gene, and the rbp2 gene. CONCLUSIONS: Our novel P. ovale rbp2 qPCR assay detects P. ovale curtisi and P. ovale wallikeri simultaneously and can be utilized to characterize the prevalence, distribution, and burden of P. ovale in malaria endemic regions. Using multilocus genotyping, we also provided the first description of the prevalence of P. ovale curtisi and P. ovale wallikeri in Western Kenya, a region holoendemic for malaria transmission.

Observed noncompliance with implementation of vector-borne disease preventive measures among deployed forces.

Failure by individual service members and units to implement preventive measures to mitigate environmental health threats have always resulted in reduced efficiency of the Warfighter, with the attendant reduction in combat capability. This article describes observations at 2 sites in northern Iraq from July 2007 to September 2009 of deficiencies in the use of preventive and protective measures to reduce incidences of vector-borne diseases. Observations included individual service member s indifference or negative attitude toward use of personal protective equipment and unit leaders failure to provide required resources and enforce use of personal protective measures. Implications of these actions and recommendation for enhancing compliance are discussed.