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WORLD HEALTH. 1991 Sep-Oct; 12.A researcher with WHO's Tropical Disease Research Programme reviews techniques used to diagnose malaria. Present techniques have not improved much since a French physician 1st used a microscope in 1880 to examine blood from a sick soldier and then noticed the parasites of Plasmodium falciparum. Yet optical quality has improved and special stains can now be used to color the parasites making them more recognizable. In fact, at a magnification of 600-700 times, a scientist can identify all 4 plasmodia, the blood forms of the plasmodia, and count the plasmodia. Blood samples and a microscope allow physicians to monitor the ill person's progress after they began treatment. Yet a microscope and the needed laboratory skills and other resources are not always present in health center in a village in countries where malaria is endemic. It is here where simple and effective techniques are needed the most. 1 approach is to detect antibodies to the plasmodia, but this takes much time. In addition, antibodies are only present after an individual has been infected for a relatively long time. Thus this technique cannot detect malaria early enough to provide proper treatment. Another approach readily identifies antigens. Yet the techniques required are complicated and require a lot of time. Besides antigen techniques are not as reliable as microscopic diagnosis. Researchers are presently experimenting on simple visual methods which are quick, inexpensive, and reliable. Molecules in the plasmodia which are in a small amount of blood will either react or not react with reagents incorporated on a dipstick or card. Thus physicians can detect what plasmodia are present and estimate parasite load. Another test can inform the physicians what antimalarial to prescribe and how much and resistance of the plasmodia to the antimalarial.
ANNALS OF TROPICAL PAEDIATRICS. 1989 Mar; 9(1):1-5.A total of 177 children seen at 2 hospitals in Kampala are described who were strongly suspected of having acquired immunodeficiency syndrome (AIDS), either on clinical grounds or because they fulfilled WHO case- definition criteria for diagnosis of pediatric AIDS. Blood was taken from the 177 children and 154 of their mothers and tested for antibody to human immunodeficiency virus (HIV) by an enzyme-linked immunoassay (ELISA). Altogether, 119 (67%) children were seropositive, but only 85 (71%) fulfilled the WHO case-definition criteria, and they were significantly older than the 34 who did not fulfill the criteria. A further 58 children were seronegative but fulfilled the WHO criteria. Of the 119 seropositive children, only 3 had a history of previous blood transfusion, but 103 (98%) of 105 mothers were HIV seropositive: consequently, their children were considered to have been infected in utero or perinatally. 13 (26%) of 49 mothers of seronegative children were seropositive. 80% of HIV-infected children were under 2 years of age at diagnosis and 23% died within 3 months of diagnosis. None of the parents was known to be an intravenous drug user, a prostitute, or bisexual. The difficulty of accurate diagnosis of AIDS presents a major problem in Africa, as the WHO clinical case-definition criteria alone are clearly not adequate. (author's)
JAMA. 1988 Dec 9; 260(22):3286-9.In Africa, as in many developing countries where AIDS has been documented, the specific serologic test for antibody to the human immunodeficiency virus is not feasible, and the case definition of the Centers for Disease Control is impracticable because facilities for diagnosing the opportunistic infections are inadequate and the clinical spectrum of AIDS is different in tropical countries. The World Health Organization developed a clinical case definition at a 1985 AIDS workshop in the Central African Republic. It was tested to determine its generalizability in Zaire, and the present paper is a report on experience using the definition to identify AIDS in Uganda. A clinical case of AIDS is defined by the presence of at least 2 major signs and 1 minor sign. The major signs are fever for more than 1 month, weight loss greater than 10%, and chronic diarrhea for more than 1 month. The minor signs are persistent cough for more than 1 month, pruritic dermatitis, herpes zoster, oropharyngeal candidiasis, ulcerated herpes simplex, and general lymphadenopathy. The presence of disseminated Kaposi's sarcoma or disseminated cryptococcosis is sufficient by itself to diagnose AIDS. The Uganda study included 1328 patients at 15 hospitals. 562 patients (42%) tested positive by enzyme-linked immunosorbent assay, and 776 (58%) tested negative. 424 patients (32%) met the world Health Organization clinical case definition for AIDS. The World Health Organization definition had a sensitivity of 55%, a specificity of 85%, and a positive predictive value of 73%. However, so many of the patients in this sample had active tuberculosis that it was decided to substitute "persistent cough for more than 1 month without concurrent tuberculosis" as a minor sign in place of "cough for longer than 1 month." With this modification 350 patients met the clinical case definition for AIDS. Sensitivity dropped to 52%, but specificity rose to 92%, and positive predictive value rose to 83%. Moreover, 26% of the seropositive females indicated amenorrhea as a symptom. Addition of amenorrhea to the modified case definition gave it a sensitivity of 56%, a specificity of 93%, and a positive predictive value of 86%. However, this is the 1st report of amenorrhea as a symptom of AIDS, and it may only be a symptom of severe weight loss in women of childbearing age. The findings in the Ugandan experience support the generalizability of the modified World Health Organization clinical case definition of AIDS and its use for surveillance purposes in Africa.