Evidence of Yersinia pestis DNA from fleas in an endemic plague area of Zambia

BACKGROUND: Yersinia pestis is a bacterium that causes plague which infects a variety of mammals throughout the world. The disease is usually transmitted among wild rodents through a flea vector. The sources and routes of transmission of plague are poorly researched in Africa, yet remains a concern in several sub-Saharan countries. In Zambia, the disease has been reported on annual basis with up to 20 cases per year, without investigating animal reservoirs or vectors that may be responsible in the maintenance and propagation of the bacterium. In this study, we undertook plague surveillance by using PCR amplification of the plasminogen activator gene in fleas. FINDINGS: Xenopsylla species of fleas were collected from 83 rodents trapped in a plague endemic area of Zambia. Of these rodents 5 had fleas positive (6.02%) for Y. pestis plasminogen activator gene. All the Y. pestis positive rodents were gerbils. CONCLUSIONS: We conclude that fleas may be responsible in the transmission of Y. pestis and that PCR may provide means of plague surveillance in the endemic areas of Zambia

Surveys for Schistosomiasis and Soil Transmitted Helminths in Luangwa, Kalabo and Serenje Districts of Zambia

Background: Earlier publications have indicated that human infections with schistosomes and soil transmitted helminths (STH) are widespread in Zambia. Despite being classified as a moderate endemic country for these infections, and a recent modelling study suggesting an average schistosomiasis prevalence of 26% among school aged children, there is a lack of published data on the present occurrence and distribution of these infections.Design: Cross sectional surveys for schistosomiasis and STH were carried out among individuals aged 4-20 years at three sites in Luangwa, Kalabo and Serenje districts, as an added component to comprehensive studies on lymphatic filariasis. Urine samples were examined for hematuria and Schistosoma haematobium ova using the Nuclepore filtration technique. Stool samples were examined for S. mansoni and STH ova using the Kato- Katz technique.Results: The prevalence of S. haematobium was generally low, with the Serenje site recording the highest of 3.0%. S. mansoni was only seen at the Kalabo site, which had a moderate prevalence of 37.5%. Hookworm infections were relatively common at all three sites, with prevalences ranging from 12.1 to 35.0%. Other more rare STH infections noted were Ascaris lumbricoides, Hymenolepis nana and Enterobius vermicularis.Conclusions: The study confirmed that schistosomiasis and STH infections were endemic at the study sites, but also suggested that the prevalences had declined compared to earlier reports. There is need for more surveys to be carried out to assess the current distribution and prevalence of these infections to provide guidance for implementation of mass drug administration for their control.

Surveys for Mansonella perstans Filariasis in Kalabo, Kazungula, Choma and Kafue Districts of Zambia

Background: Past case reports have documented Mansonella perstans infections in Zambia. However, knowledge on the epidemiology and geographical distribution of this infection in the country is lacking.  This paper reports on surveys for M. perstans in communities in four districts (Kalabo, Kazungula, Choma and Kafue) in the Southern and Western parts of Zambia.Design: The study was cross sectional. In Kalabo District, volunteers from three villages aged one year and above were recruited and had thick blood smears prepared. In the other three districts individuals aged 15 years and above who reported to selected health centres from the surrounding communities were recruited and had thick blood smears prepared. The blood smears were stained with Giemsa and examined for M. perstans microfilariae (mf).Results: A total of 1439 individuals were recruited and examined (425, 348, 306 and 360 from Kalabo, Kazungula, Choma and Kafue, respectively). No M. perstans mf were seen in any of the blood smears.Conclusions: The failure to find M. perstans mf was surprising considering previous case reports, even from some of the surveyed areas. There is a need for more surveys to be carried in other parts of the country to ascertain the distribution of M. perstans. Health practitioners should moreover be informed  about this  infection, and trained to be able to accurately distinguish M. perstans infections from those of Wuchereria bancrofti, which are also endemic in Zambia

Surveys for Mansonella perstans Filariasis in Kalabo, Kazungula, Choma and Kafue Districts of Zambia

Background: Past case reports have documented Mansonella perstans infections in Zambia. However, knowledge on the epidemiology and geographical distribution of this infection in the country is lacking. This paper reports on surveys for M. perstans in communities in four districts(Kalabo, Kazungula, Choma and Kafue) in the Southern and Western parts of Zambia.Design: The study was cross sectional. In the Kalabo District surveys, individuals aged one year and above had thick blood smears prepared and examined for M. perstans microfilariae (mf). In the other three districts the study design was retrospective and prospective, i.e. previously examined archived malaria slides from health centres were re-examined for M. perstans mf and at the same time individuals aged 15years and above had thick blood spears prepared and examined for M. perstans mf.Results: The retrospective study could only be undertaken in Choma District due to change in malaria examination method in the other districts from conventional preparation of Giemsa stained thick blood smears to use of rapid diagnostic tests. For the prospective surveys, out of the 1439 individuals recruited and examined, no M. perstans mf were seen in any of the blood smears.Conclusions: The failure to find M. perstans mf was surprising considering previous case reports, even from some of surveyed areas. There is a need for more surveys to be carried in other parts of the country to ascertain the distribution of M. perstans. Health practitioners should moreover be informed about this infection, and trained to be able to accurately distinguish M. perstans infections from those of W. bancrofti, which are also endemic in Zambia