First sero-prevalence of dengue fever specific immunoglobulin G antibodies in Western and North-Western provinces of Zambia: a population based cross sectional study.

BACKGROUND: Dengue fever is a tropical infectious disease caused by dengue virus (DENV), a single positive-stranded RNA Flavivirus. There is no published evidence of dengue in Zambia. The objective of the study was to determine the sero-prevalence and correlates for dengue fever specific IgG antibodies in Western and North-Western provinces in Zambia. METHODS: A randomized cluster design was used to sample participants for yellow fever risk assessment. In order to rule out cross reactivity with other flaviviruses including dengue, differential antibody tests were done by ELISA. Data was processed using Epi Data version 3.1 and transferred to SPSS version 16.0 for analysis. Bivariate and multivariate analyses were performed to determine the association of dengue fever with various factors. Unadjusted odds ratios (OR), adjusted odds ratios (AOR) and their 95% confidence intervals (CI) are reported. RESULTS: A total of 3,624 persons were sampled for dengue virus infection of whom 53.3% were female and 23.9% were in the 5-14 years age group. Most persons in the survey attained at least primary education (47.6%). No significant association was observed between sex and dengue virus infection (p = 1.000). Overall, 4.1% of the participants tested positive for Dengue IgG. In multivariate analysis, the association of age with Dengue infection showed that those below 5 years of age were 63% (AOR = 0.37; 95% CI [0.16, 0.86]) less likely to be infected with Dengue virus compared to those aged 45 years or older. A significant association was observed between grass thatched roofing and Dengue infection (AOR = 2.28; 95% CI [1.15, 4.53]) Respondents who used Insecticide Treated Nets (ITN) were 21% (AOR = 1.21; 95% CI [1.01, 1.44]) more likely to be infected with dengue infection than those who did not use ITNs. Meanwhile, participants who visited Angola were 73% (AOR = 1.73; 95% CI [1.27, 2.35]) more likely to be infected with Dengue virus than those who did not visit Angola. CONCLUSION: This study provides the first evidence of dengue infection circulation in both North-Western and Western provinces of Zambia. It is important that surveillance activities for Dengue and diagnostic systems are expanded and strengthened, nationwide in order to capture information related to dengue virus and other flaviviruses.

Seroprevalence of West Nile Virus specific IgG and IgM antibodies in North-Western and Western provinces of Zambia.

BACKGROUND: West Nile Virus (WNV) infection has been reported worldwide, including in Africa but its existence in Zambia is unknown. Symptoms for the virus include headache, myalgia, arthralgia and rash. OBJECTIVES: This study aimed to determine the seroprevalence of WNV and its correlates. METHODS: A cross sectional study was conducted in North-Western and Western provinces of Zambia. Samples were subjected to IgG and IgM antibodies testing against WNV. Logistic regression analyses were conducted to determine magnitudes of association. RESULTS: A total of 3,625 of persons participated in the survey out of which 10.3% had WNV infection. Farmers were 20% (AOR=0.80; 95% CI [0.64, 0.99]) less likely to have infection compared to students. Meanwhile participants who lived in grass roofed houses were 2.97 (AOR=2.97; 95% CI [1.81, 4.88]) times more likely to be infected than those who lived in asbestos roofed houses. IRS was associated with reduced risk of infection (AOR=0.81; 95% CI [0.69, 0.94]). Travelling to Angola was associated with the infection [AOR=1.40; 95% CI [1.09, 1.81]. CONCLUSION: Spraying houses with insecticide residual spray would minimize mosquito-man contact. Furthermore, surveillance at the border with Angola should be enhanced in order to reduce importation of the virus into the country.

Risk assessment for yellow Fever in Western and north-Western provinces of zambia.

BACKGROUND: North-Western and Western provinces of Zambia were reclassified as low-risk areas for yellow fever (YF). However, the current potential for YF transmission in these areas is unclear. AIMS: To determine the current potential risk of YF infection. SETTING AND DESIGN: A cross sectional study was conducted in North-Western and Western provinces of Zambia. MATERIALS AND METHODS: Samples were tested for both YF virus-specific IgG and IgM antibodies by the ELISA and YF virus confirmation was done using Plaque Reduction Neutralization Test. The samples were also tested for IgG and IgM antibodies against other flaviviruses. RESULTS: Out of the 3625 respondents who participated in the survey, 46.7% were males and 9.4% were aged less than 5 years. Overall, 58.1% of the participants slept under an impregnated insecticide-treated net and 20.6% reported indoor residual spraying of insecticides. A total of 616 (17.0%) samples were presumptive YF positive. The prevalence for YF was 0.3% for long-term infection and 0.2% for recent YF infection. None of the YF confirmed cases had received YF vaccine. Prevalence rates for other flaviviruses were 149 (4.1%) for Dengue, 370 (10.2%) for West Nile and 217 (6.0%) for Zika. CONCLUSION: There is evidence of past and recent infection of YF in both provinces. Hence, they are at a low risk for YF infection. Yellow fever vaccination should be included in the EPI program in the two provinces and strengthen surveillance with laboratory confirmation.

Clinical presentation of human African trypanosomiasis in Zambia is linked to the existence of strains of Trypanosoma brucei rhodesiense with varied virulence: two case reports.

INTRODUCTION: Trypanosoma brucei rhodesiense typically causes acute and severe human African trypanosomiasis in Zambia and other countries in Eastern and Southern Africa. Although a few atypical cases of chronic and mild forms of this disease were reported in Zambia more than 40 years ago, no such cases have been diagnosed over the last four decades. CASE PRESENTATIONS: For the first case, a 19-year-old Black African woman from the Eastern Province of Zambia presented with symptoms and signs of an atypical chronic and mild form of the disease for a period of 2 years. For the second case, a 16-year-old Black African boy from the Northern Province presented with symptoms and signs of a typical acute and severe form of the disease for 3 weeks. CONCLUSION: Two strains of T. b. rhodesiense with varying degrees of virulence still do exist in Zambia. This has implications for control strategies at the national level.

Distribution of yellow fever vectors in Northwestern and Western Provinces, Zambia.

OBJECTIVE: To determine the distribution of yellow fever (YF) vectors species in Northwestern and Western of Zambia, which sampled mosquitoes inside and outside houses in rural, urban, peri-urban and forest areas. METHODS: Back-pack aspirators spray catches and CDC light traps collected adult mosquitoes including 405 Aedes, 518 Anopheles, 471 Culex and 71 Mansonia. Morphological vector identification and PCR viral determination were done at a WHO Regional Reference Centre (Institute Pasteur Dakar), Senegal. RESULTS: The two main YF vectors were Aedes (Stegomyia) aegypti (Ae. aegypti) and Aedes (Stegomyia) africanus. The first was collected in peri-urban areas and the later was in forest areas, both sparsely distributed in Northwestern Province, where the 0.43 Breteau and 1.92 container indexes, respectively implied low risk to YF. Aedes (Aedimorphus) mutilus; Aedes (Aedimorphus) minutus and Aedes (Finlaya) wellmani were also found in Northwestern, not in Western Province. No Aedes were collected from rural peri-domestic areas. Significantly more Aedes species (90.7%, n=398) than Anopheles (9.1%, n=40) were collected in forest areas (P<0.001) or Culex species (0.2%, n=2) (P<0.001). Ae. aegypti was found only in a discarded container but not in flower pots, old tyres, plant axils, discarded shallow wells, disused container bottles and canoes inspected. CONCLUSIONS: Ae. aegypti and Aedes africanus YF vectors were found in the study sites in the Northwestern Province of Zambia, where densities were low and distribution was sparse. The low Breteau index suggests low risk of YF in the Northwestern Province. The presence of Aedes in Northwestern Province and its absence in the Western Province could be due to differing ecological factors in the sampled areas. Universal coverage of vector control interventions could help to reduce YF vector population and the risk to arthropod-borne virus infections.

Mapping the geographical distribution of lymphatic filariasis in Zambia.

BACKGROUND: Past case reports have indicated that lymphatic filariasis (LF) occurs in Zambia, but knowledge about its geographical distribution and prevalence pattern, and the underlying potential environmental drivers, has been limited. As a background for planning and implementation of control, a country-wide mapping survey was undertaken between 2003 and 2011. Here the mapping activities are outlined, the findings across the numerous survey sites are presented, and the ecological requirements of the LF distribution are explored. METHODOLOGY/PRINCIPAL FINDINGS: Approximately 10,000 adult volunteers from 108 geo-referenced survey sites across Zambia were examined for circulating filarial antigens (CFA) with rapid format ICT cards, and a map indicating the distribution of CFA prevalences in Zambia was prepared. 78% of survey sites had CFA positive cases, with prevalences ranging between 1% and 54%. Most positive survey sites had low prevalence, but six foci with more than 15% prevalence were identified. The observed geographical variation in prevalence pattern was examined in more detail using a species distribution modeling approach to explore environmental requirements for parasite presence, and to predict potential suitable habitats over unsurveyed areas. Of note, areas associated with human modification of the landscape appeared to play an important role for the general presence of LF, whereas temperature (measured as averaged seasonal land surface temperature) seemed to be an important determinant of medium-high prevalence levels. CONCLUSIONS/SIGNIFICANCE: LF was found to be surprisingly widespread in Zambia, although in most places with low prevalence. The produced maps and the identified environmental correlates of LF infection will provide useful guidance for planning and start-up of geographically targeted and cost-effective LF control in Zambia.

Challenges in the control of human African trypanosomiasis in the Mpika district of Zambia.

BACKGROUND: Human African Trypanosomiasis is one of the Neglected Tropical Diseases that is targeted for elimination by the World Health Organization. Strong health delivery system in endemic countries is required for a control program to eliminate this disease. In Zambia, Human African Trypanosomiasis is lowly endemic in the northeastern part of the country. FINDINGS: We conducted a cross-sectional survey of health institutions in Mpika district in Northern Province of Zambia from 9th to 23rd November 2011. The aim of this study was to assess current health delivery system in the management of Human African Trypanosomiasis cases in Mpika district, Northern Province of Zambia. Ten health institutions were covered in the survey. Two structured questionnaires targeting health workers were used to collect the data on general knowledge on HAT and state of health care facilities in relation to HAT management from the surveyed health institution.Only 46% of the 28 respondents scored more than 50% from the questionnaire on general knowledge about Human African Trypanosomiasis disease. None of the respondents knew how to differentiate the two clinical stages of Human African Trypanosomiasis disease. There were only three medical doctors to attend to all Human African Trypanosomiasis cases and other diseases at the only diagnostic and treatment hospital in Mpika district. The supply of antitrypanosomal drugs to the only treatment centre was erratic. Only one refresher course on Human African Trypanosomiasis case diagnosis and management for health staff in the district had been organized by the Ministry of Health in conjunction with the World Health Organization in the district in 2009. The referral system for suspected Human African Trypanosomiasis cases from Rural Health Centres (RHCs) to the diagnostic/treatment centre was inefficient. CONCLUSIONS: There are a number of challenges that have been identified and need to be addressed if Human African Trypanosomiasis is to be eliminated in a lowly endemic country such as Zambia. These include shortage of trained health workers, inadequate diagnostic and treatment centres, lack of more sensitive laboratory diagnostic techniques, shortage of trypanosomicides among others discussed in detail here.

Cannabis use and its socio-demographic correlates among in-school adolescents in Zambia.

BACKGROUND: Cannabis dependence in adolescents predicts increased risks of using other illicit drugs, poor academic performance and reporting psychotic symptoms. The prevalence of cannabis use was estimated two decades ago in Zambia among secondary school students. There are no recent estimates of the extent of the problem; further, correlates for its use have not been documented in Zambia. The objective of study was to estimate the current prevalence of cannabis use and its socio-demographic correlates among in-school adolescents. METHODS: We conducted secondary analysis of data that was obtained from the 2004 Zambia Global School-Based Health Survey. Logistic regression analysis was conducted to identify the socio-demographic factors associated with cannabis use. RESULTS: A total of 2,257 adolescents participated in the survey of which 53.9% were females. The overall prevalence of self reported ever-used cannabis was 37.2% (34.5% among males and 39.5% among females). In multivariate analysis, males were 8% (AOR = 0.92; 95% CI [0.89, 0.95]) less likely to have ever smoked cannabis. Compared to adolescents aged 16 years or older, adolescents aged 14 years were 45% (AOR = 1.45; 95% CI [1.37, 1.55]) more likely, and those aged 15 years were 44% (AOR = 0.56; 95% CI [0.53, 0.60]) less likely to report to have ever smoked cannabis. Other factors that were significantly associated with cannabis use were history of having engaged in sexual intercourse (AOR = 2.55; 95% CI [2.46, 2.64]), alcohol use (AOR = 4.38; 95% CI [4.24, 4.53]), and having been bullied (AOR = 1.77; 95% CI [1.71, 1.83]). Adolescents who reported being supervised by parents during free time were less likely to have smoked cannabis (AOR = 0.92; 95% CI [0.88, 0.95]). CONCLUSIONS: The use of cannabis is prevalent among Zambian in-school adolescents. Efforts to prevent adolescents' psychoactive drug use in Zambia should be designed considering the significant factors associated with drug use in the current study.

Prevalence and correlates for school truancy among pupils in grades 7-10: results from the 2004 Zambia Global School-based Health Survey.

BACKGROUND: There are limited data on the prevalence and associated factors of truancy in southern Africa. Yet truancy should attract the attention of public health professionals, educators and policy makers as it may be associated with adolescent problem behaviours. The objectives of the study were to estimate the prevalence and determine correlates of school truancy among pupils in Zambia. FINDINGS: We used data collected in 2004 in the Zambia Global School-based Health Survey. Logistic regression analysis was conducted to identify factors associated with truancy. A total of 2257 pupils participated in the survey of whom 53.9% were male. Overall 58.8% of the participants (58.1% of males and 58.4% of females) reported being truant in the past 30 days. Factors associated with truancy were having been bullied (AOR = 1.34, 95% CI [1.32, 1.36]), current alcohol use (AOR = 2.19, 95% CI [2.16, 2.23]), perception that other students were kind and helpful (AOR = 1.12, 95% CI [1.10, 1.14]), being male and being from the lowest school grade. Pupils whose parents or guardians checked their homework (AOR = 0.91 95% CI, [0.89, 0.92]) and those who reported parental supervision (AOR = 0.94, 95% CI [0.92-0.95]) were less likely to report being truant. CONCLUSIONS: We found a high prevalence of truancy among pupils in grades 7-10 in Zambia. Interventions aimed to reduce truancy should be designed and implemented with due consideration of the associated factors.

Disappearance of some human African trypanosomiasis transmission foci in Zambia in the absence of a tsetse fly and trypanosomiasis control program over a period of forty years.

We conducted a situation analysis of human African trypanosomiasis (HAT) in Zambia from January 2000 to April 2007. The aim of this survey was to identify districts in Zambia that were still recording cases of HAT. Three districts namely, Mpika, Chama, and Chipata were found to be still reporting cases of HAT and thus lay in HAT transmission foci in North Eastern Zambia. During the period under review, 24 cases of HAT were reported from these three districts. We thereafter reviewed literature on the occurrence of HAT in Zambia from the early 1960s to mid 1990s. This revealed that HAT transmission foci were widespread in Western, North Western, Lusaka, Eastern, Luapula, and Northern Provinces of Zambia during this period. In this article we have tried to give possible reasons as to why the distribution of HAT transmission foci is so different between before and after 2000 when there has been no active national tsetse fly and trypanosomiasis control program in Zambia.

Prevalence of hypertension and its correlates in Lusaka urban district of Zambia: a population based survey.

BACKGROUND: Hypertension is a leading cause for ill-health, premature mortality and disability. The objective of the study was to determine the prevalence and associated factors for hypertension in Lusaka, Zambia. METHODS: A cross sectional study was conducted. Odds ratios and their 95% confidence intervals were calculated to assess relationships between hypertension and explanatory variables. RESULTS: A total of 1928 individuals participated in the survey, of which 33.0% were males. About a third of the respondents had attained secondary level education (35.8%), and 20.6% of males and 48.6% of females were overweight or obese. The prevalence for hypertension was 34.8% (38.0% of males and 33.3% of females). In multivariate analysis, factors independently associated with hypertension were: age, sex, body mass index, alcohol consumption, sedentary lifestyle, and fasting blood glucose level. CONCLUSIONS: Health education and structural interventions to promote healthier lifestyles should be encouraged taking into account the observed associations of the modifiable risk factors.

Combined prevalence of impaired glucose level or diabetes and its correlates in Lusaka urban district, Zambia: a population based survey.

BACKGROUND: Developing countries are undergoing an epidemiological transition, from Communicable or Infectious to 'Non-Communicable' diseases (NCDs), such that cardiovascular disease, chronic respiratory diseases, cancer, and diabetes were responsible for 60% of all deaths globally in 2005, with more than 75% of these deaths occurring in developing countries. A survey was conducted to determine among other objectives the prevalence of diabetes and its association with physical fitness and biological factors. METHODS: A cross sectional study utilizing a modified World Health Organization's STEPwise approach to surveillance of NCDs was conducted in Lusaka district, Zambia. A multi-stage cluster sampling technique was used to select study participants of age 25 years or older. All eligible members of a household that was selected were invited to participate in the study. Unadjusted odds ratios (OR), and adjusted odds ratios (AOR) together with their 95% Confidence Intervals (CI) were obtained using Complex samples logistic regression RESULTS: A total of 1928 individuals participated in the survey, of which 33.0% were males. About half of the participants were of age 25-34 years (53.2%), and about a third of the respondents had attained secondary level of education (35.8%). The combined prevalence for impaired glucose level or diabetes was 4.0%. Age and mild hypertension were significantly associated with impaired levels of glucose or diabetes. Compared to participants in the age group 25-34 years, older participants were more likely to have impaired glucose level or diabetes (AOR = 2.49 (95%CI [1.35, 2.92]) for 35-44 years age group, and AOR = 3.80 (95%CI [2.00, 7.23]) for 45 + years age group). Mild hypertension was associated with impaired glucose level or diabetes (AOR = 2.57) (95%CI [1.44, 4.57])). CONCLUSIONS: The prevalence of diabetes in Lusaka district has not reached an alarming level and it is now that interventions targeting the younger age group 25-34 years should be put in place to curtail the spread of diabetes.