Mathematical Modeling of Host - Pest Interactions in Stage-Structured Populations: A Case of False Codling Moth [Thaumatotibia leucotreta]

False codling moth (FCM) (Thaumatotibia lucotreta) is a significant pest due to its potential economic impact on many susceptible fruits in most temperate regions of the world. Efforts to control the codling moth in the past mostly relied on the use of broad spectrum insecticide sprays, which has resulted in the development of insecticide resistance, and the disruption of the control of secondary pests. Understanding the dynamic of this pest is of great in importance in order to effectively employ the most effective control strategies. In this study, a mathematical model of host-false codling moth interactions is developed and qualitatively analysed using stability theory of system of differential equations. The basic offspring number with respect to FCM free equilibrium is obtain using next generation matrix. The condition for local and global asymptotic stability of FCM free and coexistence equilibria are established. The model is analysed numerically and graphically represented to justify the analytical results

The prevalence and antibiotics susceptibility pattern of Neisseria gonorrhoeae in patients attending OPD clinics at St. Mary?s Hospital Lacor Uganda

Introduction. Gonorrhea is one of the most common sexually transmitted infections (STIs) in developing countries, and the emergence of resistance to antimicrobial agents in Neisseria gon- orrhoeae is a major obstacle in the control of gonorrhoea. Peri- odical determination of the prevalence and monitoring of antimi- crobial susceptibility of N. gonorrhoeae is essential for the early detection of emergence of drug resistance. Methods. A total of 640 consecutive patients who attended the Outpatient Department (OPD) Clinics at St. Mary?s Hospital Lacor between Jan 2007-Dec 2011, with gonococcal urethri- tis symptoms and whose urethral swabs and high vagina swabs (HVS) were cultured, were involved in the study. Two hundred and fifty six (256) patients had positive pus swab culture, of which 151 (23.6%) showed growth of Neisseria gonorrhoeae. All the isolates were tested for antimicrobial susceptibility using the Kirby Bauer-Disc diffusion techniques. Results. Gonococcal isolates showed rapid decrease in suscepti- bility to the antimicrobials especially to Ampicillin, Tetracycline and Erythomycin, Ciprofloxacin, and intermediate to chloram- phenicol, however, Gentamicin and cefotaxime have remained as a single dose sensitive treatment for Neisseria gonorrhoeae. Sen- sitization on drug use and adopting preventive measures and con- tinuous education on safer sexual behavior through health care authorities would lead to reduction in the prevalence of Neisseria gonorrhoeae and resistance to antimicrobial. Discussion. Gonorrhea is one of the most common sexually trans- mitted infections (STIs) in developing countries, and the emer- gence of resistance to antimicrobial agents in Neisseria gonor- rhoeae is a major obstacle in the control of gonorrhea. Periodi- cal monitoring of antimicrobial susceptibility of N. gonorrhea is essential for the early detection of emergence of drug resistance

Sexual behaviour in a fishing community on Lake Victoria, Uganda

This study describes the sexual behaviour of men and women in a fishing village on the shores of Lake Victoria in southwest Uganda. The village is near a well known trading town-truckstop on the main trans-Africa highway with a high recorded prevalence of HIV infection. Data were obtained on the daily travel and sexual activities of 26 women and 54 men with particular attention paid to the rate of partner change and the proportion of sexual contacts with people outside the village. During a total of 587 person-weeks the men made 1086 trips, mostly returning home the same day. They had a total of 1226 sexual contacts, most of which occurred either in their own village (83%) or a neighbouring fishing village (11%); 17 per cent of sexual contacts were with new partners. Fifteen of the women described themselves as married; 42 per cent of their sexual contacts were with casual, paying partners. Of the eleven women who were single, between 80 and 100 per cent of contacts were with paying partners. Most of the women’s partners were resident in the village. These data show a very high rate of sexual mixing within the village but little contact with people from outside. This suggests that all sexually active men and women in the village are at high risk of STDs including HIV. There is currently no formal health care available in the village. Such communities should be targeted in future STD control programs

Low CD4 count plus coma predicts cryptococcal meningitis in Tanzania

<p>Abstract</p> <p>Background</p> <p>Largely due to the lack of diagnostic reagents, the prevalence and clinical presentation of cryptococcal meningitis in Tanzania is poorly understood. This in turn is limiting the impact of increased fluconazole availability.</p> <p>Methods</p> <p>We evaluated a cohort of 149 consecutive HIV-infected adult inpatients presenting with headache or altered mental status for clinical features, CD4 count, cryptococcal infection, and outcome. Cryptococcal meningitis was diagnosed via India ink and latex agglutination assay of CSF (<it>n </it>= 24 and 40 positive, respectively). Associations between cryptococcal meningitis and clinical features were evaluated by t-test. The sensitivity, specificity, and positive likelihood ratio of such features were determined.</p> <p>Results</p> <p>Cryptococcal meningitis was associated with confusion, social withdrawal, seizures, fever, tachycardia, meningismus, oral candidiasis, and low Glasgow coma scales and CD4 count. CD4 count < 100/μl provided the highest sensitivity for the diagnosis (93%), coma (Glasgow coma scale ≤ 8) provided the highest specificity (84%), and the combination provided the highest positive likelihood ratio (3.8). All cryptococcal meningitis patients were initiated on 800 milligrams of fluconazole daily and 50% survived to discharge, however no clinical or laboratory findings correlated with prognosis.</p> <p>Conclusion</p> <p>Cryptococcal meningitis is common among Tanzanian HIV inpatients presenting with headache or altered mental status. Purely clinical features are insensitive for establishing the diagnosis or prognosis. We advocate expanding laboratory capacity for cryptococcal antigen testing to maximize survival.</p

Ethnolinguistic structuring of sorghum genetic diversity in Africa and the role of local seed systems

Sorghum is a drought-tolerant crop with a vital role in the livelihoods of millions of people in marginal areas. We examined genetic structure in this diverse crop in Africa. On the continent-wide scale, we identified three major sorghum populations (Central, Southern, and Northern) that are associated with the distribution of ethnolinguistic groups on the continent. The codistribution of the Central sorghum population and the Nilo-Saharan language family supports a proposed hypothesis about a close and causal relationship between the distribution of sorghum and languages in the region between the Chari and the Nile rivers. The Southern sorghum population is associated with the Bantu languages of the Niger-Congo language family, in agreement with the farming-language codispersal hypothesis as it has been related to the Bantu expansion. The Northern sorghum population is distributed across early Niger-Congo and Afro-Asiatic language family areas with dry agroclimatic conditions. At a finer geographic scale, the genetic substructure within the Central sorghum population is associated with language-group expansions within the Nilo-Saharan language family. A case study of the seed system of the Pari people, a Western-Nilotic ethnolinguistic group, provides a window into the social and cultural factors involved in generating and maintaining the continent-wide diversity patterns. The age-grade system, a cultural institution important for the expansive success of this ethnolinguistic group in the past, plays a central role in the management of sorghum landraces and continues to underpin the resilience of their traditional seed system

Treatment of Cryptococcal Meningitis in KwaZulu-Natal, South Africa

BACKGROUND: Cryptococcal meningitis (CM) remains a leading cause of death for HIV-infected individuals in sub-Saharan Africa. Improved treatment strategies are needed if individuals are to benefit from the increasing availability of antiretroviral therapy. We investigated the factors associated with mortality in routine care in KwaZulu-Natal, South Africa. METHODOLOGY/PRINCIPAL FINDINGS: A prospective year long, single-center, consecutive case series of individuals diagnosed with cryptococcal meningitis 190 patients were diagnosed with culture positive cryptococcal meningitis, of whom 186 were included in the study. 52/186 (28.0%) patients died within 14 days of diagnosis and 60/186 (32.3%) had died by day 28. In multivariable cox regression analysis, focal neurology (aHR 11 95%C.I. 3.08-39.3, P<0.001), diastolic blood pressure<60 mmHg (aHR 2.37 95%C.I. 1.11-5.04, P=0.025), concurrent treatment for tuberculosis (aHR 2.11 95%C.I. 1.02-4.35, P=0.044) and use of fluconazole monotherapy (aHR 3.69 95% C.I. 1.74-7.85, P<0.001) were associated with increased mortality at 14 and 28 days. CONCLUSIONS: Even in a setting where amphotericin B is available, mortality from cryptococcal meningitis in this setting is high, particularly in the immediate period after diagnosis. This highlights the still unmet need not only for earlier diagnosis of HIV and timely access to treatment of opportunistic infections, but for better treatment strategies of cryptococcal meningitis

AIDS-defining illnesses among patients with HIV in Singapore, 1985 to 2001: results from the Singapore HIV Observational Cohort Study (SHOCS)

BACKGROUND: The objective was to describe the causes of initial and overall AIDS-defining disease episodes among HIV patients in Singapore. METHODS: A retrospective observational cohort study was performed of all adult patients seen at the national HIV referral center between 1985 and 2001. Data were extracted from the patients' records by ten trained healthcare workers. AIDS-defining conditions were established using predefined criteria. RESULTS: Among 1504 patients, 834 had experienced one or more AIDS-defining diseases. The most frequent causes of the initial AIDS-defining episode were Pneumocystis carinii pneumonia (35.7%), Mycobacterium tuberculosis (22.7%) and herpes simplex (7.4%). In total 1742 AIDS-defining episodes occurred. The most frequent causes were Pneumocystis carinii pneumonia (25.1%), Mycobacterium tuberculosis (16.2%) and cytomegalovirus retinitis (9.5%). CONCLUSIONS: The most frequent causes of AIDS-defining illnesses in Singapore are similar to those reported in the West, prior to the introduction of anti-retroviral therapy. Opportunistic infections remain the most frequent AIDS-defining illnesses

Survival by AIDS defining condition in rural Uganda

Objectives: To report the initial AIDS defining conditions, CD4 lymphocyte counts around the time of AIDS diagnosis, and survival by AIDS defining condition in a population based cohort in rural Uganda. Methods: Participants in an HIV natural history cohort in rural Uganda were reviewed every 3 months at routine visits and at other times when they were ill. The date and nature of the first AIDS defining condition in participants developing AIDS during follow up between the start of the cohort in 1990 and the end of 1998 were noted. The CD4 count at, or within, 3 months of this time was recorded for those participants who developed AIDS (WHO stage 4) after 1993. Results: The median survival from developing AIDS to death was 9.3 months and the median CD4 lymphocyte count around the time of developing AIDS was 150 cells x10(6)/l. The most frequent AIDS defining conditions were wasting syndrome, oesophageal candidiasis, and mucocutaneous herpes simplex virus infection (HSV) for more than 1 month. The median survival with wasting syndrome, Kaposi's sarcoma, and oesophageal candidiasis was less than 3.5 months; however, survival with cryptosporidial diarrhoea, chronic HSV, and extrapulmonary tuberculosis was greater than 20 months. There was little relation between CD4 count around the time of development of the AIDS defining condition and the median survival with that condition. Conclusions: The survival for most AIDS defining conditions was generally shorter and the median CD4 lymphocyte count higher than studies reported from developed countries. However, the conditions with the longest survival (cryptosporidial diarrhoea, chronic HSV, and extrapulmonary tuberculosis) had a similar survival to that in developed countries and these conditions have a high background level in this population. Key Words: AIDS; survival; Afric

The extended family and support for people with AIDS in a rural population in south west Uganda: A safety net with holes?

It is commonly assumed that the extended family in Africa provides a safety net for individuals in times of need. This paper examines this assumption using data on the care of people with AIDS in a rural population in South West Uganda. Over a six month period data were collected by counsellors on the care given to 30 (17 women, 13 men) AIDS patients by their families. In 27 of the 30 cases there was evidence of limited care. Various reasons were given for this by the carers, including lack of food and money for medications and the carer's other family responsibilities. For 17 clients who died during the study period, records of seven cases show that other relatives were asked to help with care but refused on the grounds of poverty or other commitments. However, in all but one of these cases extended families did provide assistance for the funeral. The findings suggest that there is a need to question the assumption that the extended family, in the culture under study, is able to provide adequate support for AIDS patients

Herpes zoster and HIV-1 infection in a rural Ugandan cohort.

OBJECTIVE: To compare the rates and clinical features of herpes zoster in HIV-positive and HIV-negative individuals in a cohort in rural Uganda; to report the incidence of herpes zoster in the HIV-positive group in relation to seroconversion and CD4 cell counts and to determine whether it is indicative of a more rapid progression to death. DESIGN: A prospective population-based cohort. METHODS: The cohort comprised 107 prevalent and 144 incident (with documented dates of seroconversion) participants with HIV infection and 231 HIV-negative controls who were reviewed routinely every 3 months. RESULTS: The mean rate of herpes zoster was 53.6/1000 person-years in HIV-positive and 4.4 in HIV-negative participants. The cumulative incidence of a first episode of herpes zoster was 7.6% at 2 years, 12.6% at 4 years and 24.0% at 6 years after seroconversion; the incidence rate was 35.6/1000 person-years. There was no evidence of a significant effect of age, gender, period from seroconversion or CD4 cell count on this incidence rate. Herpes zoster was an indicator of HIV-1 infection in this population but not an indicator of more rapid progression to death after adjusting for CD4 cell count and age. CONCLUSIONS: The rates, including the cumulative incidence after seroconversion and the clinical presentation of herpes zoster, were similar to those reported from industrialized countries. Although an indicator of HIV-1 infection in this population, herpes zoster was unrelated to CD4 cell count or period from seroconversion and did not lead to a faster disease progression