Nabila Khalid

Unique Endemicity of Cryptosporidiosis in Children in Kuwait

ABSTRACT To understand the transmission of Cryptosporidium infection in children, fecal specimens from 62 Kuwaiti children with gastrointestinal symptoms found to be positive by microscopy were genotyped and subtyped with a small subunit rRNA-based PCR-restriction fragment length polymorphism analysis and a 60-kDa glycoprotein-based DNA sequencing tool. The median age of infected children was 4.5 years, and 77% of infections occurred during the cool season of November to April. Fifty-eight of the children (94%) had Cryptosporidium parvum, three (5%) had Cryptosporidium hominis, and one (1%) had both C. parvum and C. hominis. Altogether, 13 subtypes of C. parvum (belonging to four subtype allele families) and C. hominis (belonging to three subtype allele families) were observed, with 92% of specimens belonging to the common allele family IIa and the unusual allele family IId. Thus, the transmission of cryptosporidiosis in Kuwaiti children differed significantly from other tropical countries.

Comparison of Two Commercial Assays with Expert Microscopy for Confirmation of Symptomatically Diagnosed Malaria

ABSTRACT Conventional light microscopy has been the established method for malaria diagnosis. However, recently several nonmicroscopic rapid diagnostic tests have been developed for situations in which reliable microscopy may not be available. This study was conducted to evaluate the diagnostic performance of a recently introduced ICT Malaria Pf/Pv test. This assay detects Plasmodium falciparum histidine-rich protein 2 antigen (PfHRP-2) for P. falciparum diagnosis and pan-malarial antigen for P. vivax diagnosis. In this study we compared the performance of ICT Malaria Pf/Pv with microscopy of Giemsa-stained blood films and with an OptiMAL test that detects Plasmodium lactate dehydrogenase (pLDH) antigen. A total of 750 clinically suspected malaria patients were examined at local health centers in Kuwait. Both the antigen tests had a high degree of specificity (>98%) for detection of malaria infection. However, they were less sensitive than microscopy. Compared with microscopy the ICT Malaria PF/pf test failed to detect malaria infection in 93 (34%) of 271 malaria patients (11% of patients with P. falciparum and 37% of patients with P. vivax) and the OptiMAL test failed to detect malaria infection in 41 (15%) of 271 malaria patients (7% of patients with P. falciparum and 13% of patients with P. vivax). The sensitivities of the ICT Malaria Pf/Pv and OptiMAL tests for detection of P. falciparum infection were 81 and 87%, and those for detecting P. vivax were 58 to 79%, respectively. The sensitivity of the ICT Malaria Pf/Pv and OptiMAL tests decreased significantly to 23 and 44%, respectively, at parasite densities of <500/μl. Both of the tests also produced a number of false-positive results. Overall, the performance of the OptiMAL test was better than that of the ICT Malaria Pf/Pv test. However, our results raise particular concern over the sensitivity of the ICT Malaria Pf/Pv test for detection of P. vivax infection. Further developments appear necessary to improve the performance of the ICT Malaria Pf/Pv test.

Cysticercosis: imported and autochthonous infections in Kuwait

Intracerebral and non-central nervous system (non-CNS) cysticercosis caused by the larval pork tapeworm Taenia solium was diagnosed in patients in an Islamic state. The mode of transmission and challenges in diagnosis are highlighted. Sixteen patients with neurocysticercosis and six with non-CNS lesions were diagnosed by imaging studies (computerized tomography [CT]/magnetic resonance imaging [MRI]) and serology (ELISA and/or enzyme-linked immunoelectrotransfer blot assay [EITB]). Four of 55 family members, including servants, tested for antibodies were positive by the EITB and ELISA. Only one of these sera tested for antibodies to adult T. solium was positive: that of the cook, the probable source of the infection. We postulate a similar mode of transmission in the other Kuwaitis. Evaluation of several commercially available ELISA kits showed they were of poor specificity. Even in countries where pork consumption is proscribed by religious laws, physicians should include cysticercosis in their differential diagnosis in patients with neurological symptoms or non-CNS lesions, especially in non-endemic countries with a large expatriate population such as Kuwait. In children particularly, and in this region, suspected tuberculous lesions on CT must be investigated to rule out cysticerci by a more diligent use of the sensitive and specific EITB assay. Failure to understand the local epidemiology leads to empirical, inappropriate and prolonged therapy for chronic disease.

Cryptosporidiosis in Kuwaiti children: association of clinical characteristics with Cryptosporidium species and subtypes

To determine the association of clinical characteristics with Cryptosporidium types and subtypes, faecal specimens from 2548 children with diarrhoea were screened by microscopy for Cryptosporidium spp., and positive specimens were genotyped and subtyped by PCR-RFLP. A total of 87 of the 2548 children (3.4 %) had cryptosporidial diarrhoea by microscopy and the majority (41.4 %) of the infected children were in the 4-8-year-old age group. Molecular characterization of the 83 children studied further (4 had mixed infections and were not subtyped) showed that Cryptosporidium parvum was the most commonly identified species (73.5 %) and consisted of three subtypes: IIa and IId were the most common (80.3 %), followed by IIc. Twenty-two (26.5 %) of the children had Cryptosporidium hominis and showed three subtypes: Id was the most common (54.5 %), followed by Ia (36.4 %) and Ie. Associated clinical manifestations varied between C. parvum and C. hominis. Diarrhoea associated with subtype Id, the most commonly identified C. hominis subtype, was more severe than that associated with other subtypes. In conclusion, this study confirmed a very different Cryptosporidium genotype and subtype distribution compared with other tropical countries among Kuwaiti children with diarrhoea, with a predominance of C. parvum IIa and IId. In addition, subtype Id of C. hominis was associated with more diverse and severe clinical manifestations in infected children, suggesting that parasite genetics may play an important role in the clinical manifestations of human cryptosporidiosis.

Performance of Rapid Malaria PF Antigen Test for the Diagnosis of Malaria and False-Reactivity with Autoantibodies

Recently introduced rapid nonmicroscopic immunocapture assays for the diagnosis of malaria infection are being evaluated for their sensitivity and specificity in various epidemiological settings. A Plasmodium falciparum histidine-rich protein-2 (PfHRP-2)-based assay (ICT malaria Pf assay) was evaluated for its performance and compared to that of Giemsa-stained thick blood film microscopy. Of the 515 patients tested, 163 were positive for malaria parasites on thick blood film microscopy: 87 were infected with P. vivax; 63 with P. falciparum; 1 with P. malariae; and 12 with both P. falciparum and P. vivax. The ICT assay detected 53 P. falciparum infections and, as expected, failed to detect all but one case of P. vivax. Three cases of mixed infections were also not detected by this assay. The performance of the ICT assay in diagnosing P. falciparum infection was comparable to that of microscopy. The sensitivity of the ICT assay was 82% and the specificity 99.0%. The ICT assay also detected 4 false-positive cases. These patients reported treatment with chloroquine in the previous 2-5 weeks. The specificity of the assay was evaluated in different groups of patients, who had tested negative for malaria infection by microscopy. These patients were selected from different disease groups: rheumatoid arthritis; hepatitis C; toxoplasmosis; schistosomiasis; and hydatid disease. Of the 225 patients studied, 133 were positive for rheumatoid factor. Thirty-five (26%) of the 133 patients had false positive-reactions with the ICT assay, while only four had false positive-reactions with the OptiMAL test. After the rheumatoid factor was absorbed 33 of the 35 false-positive specimens were negative when retested with the ICT assay. Our study shows that the PfHRP-2-based ICT assay gave a false positive-reaction in 26% of the patients who had rheumatoid factors, but were negative for malaria by microscopy. We conclude that new rapid nonmicroscopic methods for the diagnosis of malaria that complement or support blood film microscopy would be of great use in the diagnosis and treatment of patients with malaria and also in epidemiological studies.

Modified Giemsa Staining for Rapid Diagnosis of Malaria Infection

Objectives: To develop and evaluate a rapid method for the diagnosis of malaria infection by microscopy of stained blood films. Subjects and Methods: Blood specimens were collected from randomly selected confirmed malaria cases (n = 75) and suspected malaria cases (n = 175). The microscopy was done on each set of blood films stained by modified and the standard Giemsa staining methods. Results: All the 75 previously diagnosed malaria cases were confirmed by the microscopy of blood films stained by both methods. Forty-nine (28%) of the 175 cases suspected for malaria infection showed malarial parasites on microscopy of blood films stained by both methods. However, due to homogeneous staining and clearer background of the blood films it was possible to determine the parasite species in 65% of the cases on microscopy of the thick films stained with the modified method compared to only 20% with the standard method. Further, the turnaround time for reporting the microscopy test result was 15–20 and 45–50 min with modified and standard staining methods, respectively. Conclusion: Our data showed that performance of the modified staining method in detecting malarial parasites was comparable to that of the standard staining method. Moreover, the modified staining method was rapid, easy to use, and reliable.

Pressure sores and myiasis: flesh flies (Diptera: Sarcophagidae) complicating a decubitus ulcer

Myiasis is the infestation by dipterous larvae of the tissues of humans, other mammals and some other vertebrates, most commonly affecting cutaneous tissues close to natural orifices or wounds. Such infestation may be deleterious, when the larvae attack the host’s healthy tissues, or it may be benign, when the larvae confine their activities to diseased and dead tissue. In clinical settings, carefully controlled myiasis can even be of benefit to the host, helping to clear areas of necrosis from wounds and ulcers, in an approach often known as ‘maggot therapy’ (Sherman et al., 2000). In Kuwait, a desert country where one might expect a fairly restricted insect fauna because of the hot and dry environment, several cases of human myiasis have been described, including ophthalmomyiasis caused by Oestrus ovis (in the family Oestridae), intestinal myiasis caused by Megaselia sp. (Phoridae) and O. ovis, and urinary myiasis caused by Psychoda sp. (Psychodidae) (Hira et al., 1997). Although all of these infestations were community-acquired, nosocomial infections by the larvae of Lucilia sericata (Calliphoridae) and M. scalaris have also been reported in Kuwait (Hira et al., 2004). An autochthonous case of human myiasis caused by a fly species from yet another family, the Sarcophagidae, which was complicating a decubitus ulcer, has also recently been observed in Kuwait (see below).