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Sensitive and specific diagnostic methods of schistosomiasis at an early stage of infection are crucial to avoid irreversible pathological reactions induced by eggs. This study aimed to evaluate the PCR technique for detection of free circulating Schistosoma mansoni DNA in serum in the early prepatent period in experimentally infected mice, in comparison to the commonly used indirect hemagglutination assay (IHA) for the detection of bilharzial antibody and stool examination. Sixty-four mice were experimentally infected with S. mansoni, and every 3 or 4 days through the 8 weeks postinfection (p.i.), serum samples were collected from randomly chosen four infected mice, then pooled and examined for circulating DNA and bilharzial antibody. The results showed that the earliest deposition of eggs in the small intestine was observed at the fifth week p.i., and the eggs were detected in feces in the seventh week p.i. PCR detected free circulating DNA of S. mansoni starting from the third day p.i., while IHA failed to detect infection up to the eighth week p.i. It is concluded that detection of free circulating DNA by PCR can be used as a valuable test for early diagnosis of prepatent S. mansoni infection.

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. It was reported to account for about 4.7 % of chronic liver disease in Egyptian patients. The present study aimed at studying the different factors that may be implicated in the relationship of schistosomiasis mansoni with HCC in Egypt. A total of 75 Egyptian patients with primary liver tumours (HCC) were enrolled in this study. They were subjected to full history taking and indirect hemagglutination assay (IHA) for the diagnosis of schistosomiasis. According to the results, the patients were categorized into two groups: Group I: 29 patients with negative IHA for schistosomiasis and hepatitis C virus (HCV) positive with no history or laboratory evidence of previous or current Schistosoma mansoni infection. Group II: 46 patients with positive IHA for schistosomiasis and HCV positive. The significant higher proportion of HCC patients in the present study had concomitant HCV and schistosomiasis (61.3 %) compared to HCC patients with HCV alone (38.7 %) suggesting that the co-infection had increased the incidence of HCC among these patients. Analysis of the age distribution among HCC patients revealed that patients in Group II were younger in age at time of diagnosis of HCC with mean age 57.1 years, as compared to patients in Group I with mean age 64.3 years with a highly significant statistical difference between the 2 groups. HCC in Group II was more common in rural residents while it was more common in urban areas in Group I with a significant statistical difference between the 2 groups. Analysis of the sex distribution among the studied groups showed that HCC was more common in males than females in both groups. As regards the aggression of HCC, it was more commonly multifocal and larger in size in patients with concomitant infection than in patients with HCV alone.

Gene mutation may occur either in the parasite or in the host, which may be beneficial or harmful for each. As we previously discussed, part I covered causes and types of gene mutations as well as their relation(s) to or effect(s) on parasitic diseases; part II deals with parasite gene mutations. The most apparent manifestation is drug resistance especially with anti-malarial drugs for falciparum malaria. The majority of P. falciparum isolates are able to undergo gene mutations in genes encoding enzymes that control drug uptake. Parasite gene mutations are suggested to influence parasite virulence in toxoplasmosis and malignant malaria, and to have impact on the occurrence of malignancy in schistosomiasis and clonorchiasis. It is intended in the present review to present mechanism(s) of drug resistance due to parasite gene mutations, with special emphasis on anti-malarial drugs, albendazole, metronidazole, and other drugs used in treatment of African trypanosomiasis and toxoplasmosis. The review also presents other effects of parasite gene mutations on disease outcome and progress as well as occurrence of false diagnosis in falciparum malaria using ICTs utelizing histidine rich protein.

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