Meru District Research Articles

Jomo Kenyatta and the repression of the ‘last’ Mau Mau leaders, 1961–1965

ABSTRACTAround the time of independence (1961–1965), Kenya’s African nationalist government organized the continued repression of the remaining Mau Mau fighters who had refused to surrender after the ending of the Emergency in January 1960. This article focuses on Meru district, in Eastern Province, where Mau Mau fighters gathered under the leadership of Field Marshalls Mwariama and Baimungi. Documents from the Kenyan National Archives, in particular the correspondence of the provincial administration and security reports, show that politicians and officials alike saw the remaining fighters in Meru as a potent political threat to the nationalist government of Jomo Kenyatta. Kenya’s government sought to deal with the Mau Mau threat by co-opting its leaders, while Kenyatta carefully distanced the presidency from the government’s choice of repressive politics. A symbolic propaganda campaign was organized to maintain the myth that Kenyatta had always been the Mau Mau leader the British arrested and jailed in 1953, despite the reality of Kenyatta’s repeated denunciation of the movement. After 1963, the President continued to ignore Mau Mau fighters’ fundamental claims over land redistribution. This article shows that the Mau Mau were not simply ‘forgotten’, and uncovers the role of the military and the silent tactics of repression organized by the Kenyan independent government.

Challenges Facing Small Scale Entrepreneuresin Accessing Loan from Banks at Ngongongare, Meru District, Arusha Region in Tanzania

Challenges Facing Small Scale Entrepreneuresin Accessing Loan from Banks at Ngongongare, Meru District, Arusha Region in Tanzania

Pesticide exposure from fresh tomatoes and its relationship with pesticide application practices in Meru district

AbstractTomato pesticides health risk was assessed in Meru district of Arusha region, one of the key tomato producers in Tanzania. Tomato samples and consumption information were collected from 50 farmers using Food and Drug Administration standards and twice administered twenty-four hour recall questionnaire respectively. Analysis for pesticide residues was done using Gas Chromatography Mass Spectrometry. Dietary pesticide exposure was estimated deterministically by combining pesticide residue levels and tomato consumption levels. Pesticide levels were detected for; permethrin (mean, 5.2899 mg/kg/day), chlorpyrifos (mean, 7.5281 mg/kg/day) and ridomil (mean, 2,854.279 mg/kg/day) in 18% of samples. Health Risk Indices, determined as ratio of estimated daily intake to acceptable daily exposure, for chlorpyrifos, permethrin and ridomil were greater than one. This implies that, lifetime consumption of fresh tomatoes can pose health risk for chlorpyrifos, permethrin and ridomil. Awareness raising on good prac...

To Examine Economic Factors Influencing Citizen Participation in Local Governance in Meru District Council - Tanzania

To Examine Economic Factors Influencing Citizen Participation in Local Governance in Meru District Council - Tanzania

Assessment of raw milk quality and stakeholders' awareness on milk-borne health risks in Arusha City and Meru District, Tanzania.

A cross-sectional study was conducted to assess the quality of raw milk and stakeholders' awareness on milk-borne health risks and factors for poor milk hygiene in Arusha City and Meru District, Tanzania between October and December 2012. A total of 105 smallholder dairy farmers, milk vendors and milk retailers were interviewed, and milk samples were collected for physical, microbial and antibiotic residue analysis using standard procedures. Questionnaire results indicated high level of awareness (94%) that drinking raw milk can predispose consumers to milk-borne diseases; nevertheless, 65% of respondents consumed raw milk. Physicochemical analyses showed some of the milk had sediments (20%), bad smell (21%) and had clotted on alcohol test (27%). About 36% of milk samples had pH below 6.6, and 25% had specific gravity below 1.028g/ml. The mean total viable count (TVC) of milk from vendors is significantly (P < 0.05) higher than that from retailers and smallholder dairy farmers. Generally, 65% of milk samples assessed had a higher TVC than the level recommended (2.0 × 10(5)cfu/ml) by the East African Community (EAC) standards. Up to 91% of the milk samples had bacterial growth that included Eschericia coli (66%), Staphylococcus aureus (33%), Corynebacterium (11%) and Pseudomonas (10%). All smallholder dairy farmers were aware of drug residues, but majority (57%) were unaware of human health effects caused by veterinary drug residues in milk. Up to 97% of respondents reported to comply with drug withdrawal periods. This possibly led to all milk samples analysed to be negative from detectable levels of antibiotic residues. It is concluded that the level of awareness on milk quality is high, although practices associated with milking and post-harvest handling predispose milk to bacterial contamination which is a public health risk to milk consumers.

Origins of Human-Wildlife Conflicts in Meru District, 1920-1939

Human-wildlife conflicts have been a major problem in parts of Meru District since the 1920s. There have been numerous cases of loss of human lives due to wild animal attacks, predation of livestock and crop destruction by wild animals in the district. Despite the magnitude of humanwildlife conflicts (HWC) in the district, the underlying causes for the conflicts have not been studied. This study therefore examined the social, political and economic aspects of HWC in Meru District in the period 1920 to 1939. The study analysed the impact of wildlife conservation on people’s livelihoods and the responses by government and local communities to the conflicts. To achieve these objectives, the political ecology perspective was used. This perspective examines interactions between political, economic, social and environmental factors over time. The research relied on both secondary and primary sources. The former included published works that were obtained from various resource centres, while the latter were obtained from the Kenya National Archives (KNA) and field interviews. Sources from the KNA included both monthly and annual reports from the provincial administration and the Ministry of Wildlife and Tourism. Oral interviews were also conducted in the study area. Forty informants were interviewed during fieldwork. Purposive sampling was used in selecting the informants. This ensured that only knowledgeable persons were interviewed. Initial informants directed the researcher to other potential informants. Interview schedules targeting local residents, the provincial administration and wildlife conservation agents were used. These categories of informants enriched the study through different perspectives to the HWC Phenomenon. Data analysis involved usage of “data cards” that were useful in sorting out data. The cards were categorised according to the themes highlighted in the study objectives. Chronology was also used in the categorisation of “data Cards.” In the analysis, the data were tested against the objectives of the study. The study found out that, while there were efforts to ameliorate HWCs in the district which included logging, poaching and destruction of crops and livestock by wild animals, the methods used were ineffective. The findings of the study may assist policy-makers to formulate wildlife conservation policies that could help ameliorate HWC, which could lead to improved standards of living in the district.

The quality of care in family planning: a case study of Chogoria, Eastern Kenya

This paper compares the quality of family planning services in the catchment areas of Chogoria and Maua hospitals, both in the Meru district of Kenya. The quality issues compared are personnel, types of methods, information, recruiting and counselling of clients, knowledge and source of modern contraceptives, desired family size, use of contraceptives, and satisfaction of providers and clients. A comparative approach is adopted to study the aspects of family planning that have made Chogoria relatively more successful than Maua and the rest of Kenya. The data used in this analysis is qualitative and was collected through personal observation, interviews, and group discussions with health care providers. The results show that while the family planning programmes of Chogoria and Maua are comparable in many respects, there are also important differences. For example, Chogoria family planning personnel were more knowledgeable about contraceptives and were more satisfied with the training provided by Chogoria hospital than were their counterparts in Maua. The relationship between the senior and the junior staff was more cordial in Chogoria. The content of the information about contraceptives provided to women attending clinics was similar in both hospitals. But the teachers in Chogoria were more knowledgeable and confident than those in Maua. In Chogoria, the decision to use family planning is jointly taken by the husband and the wife, and if a client fails to turn up for an appointment a follow-up is scheduled. In Maua, the decision to use family planning is taken unilaterally by the wife and defaulters are not followed up. The study showed that 78 percent and 33 percent of the participants were using modern family planning methods in Chogoria and Maua respectively. Three conclusions are drawn from the study. First, that the satisfaction of family planning providers and their clients contributes positively towards more knowledge and use of modern contraceptives. Second, that women feel more secure and comfortable with the methods they use if their husbands are involved in deciding whether or not to adopt them. Finally, follow-up services for those who fail to attend appointments helps to strengthen rapport between providers and clients and provides an opportunity to learn of the circumstances that lead to discontinuing the use of contraceptives.

Detecting change in the status and habitat of Hinde's BabblerTurdoides hindei: 2000 to 2011

Department of Zoology, National Museums of Kenya,PO Box 40658-00100, Nairobi, KenyaBACKGROUNDThe globally Vulnerable Kenyan endemic Hinde’s Bab-bler Turdoides hindei has its stronghold in the foothills ofMt Kenya and the Aberdares, where it is associatedmainly with patches of scrub and riverine thicket (Statt-ersfield et al. 1998, Njoroge & Bennun 2000, BirdLifeInternational 2012). A decline in its known range, firstdescribed in the 1970s, was attributed to scrub clearancefor cultivation, perhaps compounded in some areas byhuman disturbance and hunting (Plumb 1979, Njorogeet al. 1998). Surveys in 1994 and 2000–2001 showedthat the species was much less abundant within pro-tected areas than in fertile, densely populated farmland,offering limited scope for conservation through furthersite designation (Shaw & Musina 2003).The global range of Hinde’s Babbler lies predomi-nantly within the catchments of the upper Tana River,with outlying populations in Meru District, Machakos,Kitui and Nziu (Shaw et al. 2003). By 2001 the specieswas known from just seven main areas, and was thoughtto have a global population of c. 1500–5600 birds.Although scrub clearance has impacted on the species’range and population, its effect may have been partlymitigated by the spread of the exotic invasive Lantanacamara, which provides scrub cover in areas previouslycleared of native shrubs, enabling the Babbler to persistin, and possibly to re-colonize, intensively farmed land(Njoroge & Bennun 2000).Like most members of its genus, Hinde’s Babblerbreeds cooperatively, groups typically comprising threeto four adults (range 1–8), often accompanied by one ortwo juveniles (Njoroge & Mutinda 1996, Shaw & Musi-na 2003). Some groups include individuals with exten-sive light feathering on the chest, head and back,sometimes distributed asymmetrically, a trait interpretedby Plumb (1979) as possible evidence of inbreeding.In 2011 we reassessed the global range of Hinde’sBabbler and resurveyed three sites previously surveyedin 2000–2001, to determine whether changes hadoccurred in its known range, abundance, demography orhabitat over the intervening decade. To determine therelationship between plumage type, population densityand breeding success we assigned a plumage score to allindividuals seen sufficiently clearly, noting their age classand group composition.GLOBAL RANGEChanges in Hinde’s Babbler’s global range were estimatedfrom the number of occupied 10 9 10-km squares (itsArea of Occupancy) and from the number of squaresbounded by these known sites (its Extent of Occurrence).Three time periods were compared: 1900–1970,1971–1990 and 1991–2011. Since its discovery in 1900,Hinde’s Babbler has been recorded in 53 squares, indicat-ing an Area of Occupancy of c. 5300 km

‘Youth in a void’: sexuality, HIV/AIDS and communication in Kenyan public schools

The disappearance of traditional sex education during rites of passage in African societies has left many youth uncertain of where to look for information. Against this backcloth, the objectives of this study were to identify knowledge gaps amongst adolescents in Kenya regarding sexuality, HIV/AIDS and reproductive health. A thematic analysis was conducted of questions posed by 735 school youth aged 12–18 years from Meru and Kajiado Districts. Results show that many questions showed curiosity and anxiousness. Knowledge appeared to be fragmented and sometimes revealed misconceptions, which may put youth at risk. The raised themes differed by gender and age. Questions on saying no to sex, sexual violence and female circumcision were a great concern for girls. Boys were more concerned with managing boy–girl relationships, preventing STI/HIV infection, and condoms. Concern about transition to adulthood, sexuality, STI and HIV/AIDS, myths and misconceptions, and intergenerational communication cut across both genders. Older teens were more concerned with questions on boy–girl relationships, norms and values regarding sexuality, and STI. Younger teens ( < 15 years) wanted to know about reproduction, saying no to sex, HIV/AIDS, condoms, sexual violence and female circumcision. Compounding these challenges was the lack of intergenerational communication. The study identified important knowledge and communication gaps in sexual and reproductive health among in-school adolescents in Kenya. There is a need for sex education interventions for different age groups and genders. These interventions should work with parents, teachers and health professionals.

Voices unheard: Youth and sexuality in the wake of HIV prevention in Kenya

Objective The aim of the study was to explore the concerns of young people on sexuality in its social contexts in the era of HIV/AIDS in three districts in Kenya. Study design Young people in Kajiado, Kirinyaga and Meru Districts were requested to write questions on sexuality and related problems that later formed the basis for discussion in community dialogue meetings with adults. The social ecological conceptual model (SEM) was used to illuminate the contextual factors and actors influencing sexual behaviours among young people. Results The study suggests that young people and adults are concerned about honest and open communication on sexuality. Predominant concerns for the young people were love, sexual urge, desires or sexual wellness and condom use. Their questions suggest that young people are sexually active, yet have little knowledge on sexual matters. The results describe a prohibitive silence from adults, an issue reflected in the questions from the school youth. Conclusion This study suggests the need to move from seeing sexuality as a problem and focus on sexual wellness and the positive aspects of sexuality. The adult participants suggested that bringing men and women together for reflection and discussion in a participatory mode, transformative learning and change could be achieved. It is vital that the youth and adults have open communication as a foundation for youth to mature into adults. This can be achieved, if interventions including research address multiple contextual factors such as cultural norms, gender differences, as well as communication barriers.

A New Species of Yam from Kenya, Dioscorea kituiensis Pollen Morphology, Conservation Status, and Speciation

Comparative morphological studies of specimens included in Dioscorea gillettii from Kenya and Ethiopia show differentiation between a northern group of populations in Sidamo and Bale Provinces in Ethiopia and near Moyale in northern Kenya and a southern group found in Kitui and Meru Districts of Kenya. Thus the southern element is described as a new species. The two species also differ in their pollen morphology. An illustration, distribution map, and a conservation status assessment are provided for D. kituiensis, and its mode of speciation is discussed.

Conservation and Promotion of Indigenous Plants and Trees in Meru: A preliminary survey

The research team set out on 8 August 2007 to visit Mr. Samson Mathiu's farm at Ntharu, Nkueni division, Mikumbune location, South Imenti, Meru district. Samson is an active environmentalist and expert on indigenous plants. He had been identified as a potential resource during the Memorialization & Museums Workshop facilitated by Prof Karega-Munene and held at USIU in May 2007. As part of its outreach and collaboration strategy, the SDIC team conducted an extensive two-day research in the area with the assistance of Samson and his friend Francis Kirimi Inoti. A great deal of notes were made and photographs taken on African indigenous trees and crops. The team returned to USIU on 10 August 2007. Of great interest to the research team was the evidence of the transit situation that exist in our rural areas moving from indigenous to current lifestyles within three generations in the region. According to Ibui (2007), the former were acquired over several generations and allowed the locals to use, manage and conserve wild resources in a sustainable mode. In the teams' observation, society's emphasis on a monetary system has seen a shift in plant value systems.Journal of Language, Technology and Entrepreneurship in Africa Vol. 1 (1) 2007 pp. 119-125

Antimalarial activity of some plants traditionally used in Meru district of Kenya

Ten plant extracts commonly used by the Meru community of Kenya were evaluated for the in vitro antiplasmodial, in vivo antimalarial, cytotoxicity and animal toxicity activities. The water and methanol extracts of Ludwigia erecta and the methanol extracts of Fuerstia africana and Schkuhria pinnata exhibited high antiplasmodial activity (IC(50) < 5 microg/mL) against chloroquine sensitive (D6) and resistant (W2) Plasmodium falciparum clones. The cytotoxicity of these highly active extracts on Vero E6 cells were in the range 161.5-4650.0 microg/mL with a selectivity index (SI) of 124.2-3530.7. In vivo studies of these extracts showed less activity with chemosuppression of parasitaemia in Plasmodium berghei infected mice of 49.64-65.28%. The methanol extract of Clerodendrum eriophyllum with a lower in vitro activity (IC(50) 9.51-10.56 microg/mL) exhibited the highest chemosuppression of 90.13%. The methanol and water extracts of Pittosporum viridiflorum were toxic to mice but at a lower dose prolonged survival of P. berghei infected mice (p < 0.05) with no overt signs of toxicity. However, the extracts were cytotoxic (SI, 0.96-2.51) on Vero E6 cells. These results suggest that there is potential to isolate active non-toxic antimalarial principles from these plants.

Traditional phytotherapy of some remedies used in treatment of malaria in Meru district of Kenya

In Kenya, most people especially in rural areas use traditional medicine and medicinal plants to treat many diseases including malaria. Malaria is of national concern in Kenya in view of development of resistant strains of Plasmodium falciparum to drugs especially chloroquine, which had been effective and affordable. This has led the Government to provide free antimalarial treatment because the cost of newer antimalarial drugs is unaffordable to local communities. However, traditional remedies against malaria are practised among the rural communities because of ease of availability and convenience and also due to social, psychological and cultural reasons. This paper examines the use of antimalarial plants among the Meru community of Imenti forest area and Gatunga, in Eastern Province, Kenya. Forty seven plant species belonging to 28 families were encountered during the study. Rutaceae, Compositae and Celestraceae families represented the species most commonly cited in treatment of malaria. Six plant species namely: Periploca linearifolia, Maytenus heterophylla, M. putterlickioides, Albizia amara, Teclea simplicifolia and Olea capensis are documented for the first time for treatment of malaria.

Chemical composition and antimicrobial activity of the essential oil of Ocimum gratissimum L. growing in Eastern Kenya

Hydro-distilled volatile oils from the leaves of Ocimum gratissimum L. (Lamiaceae) from Meru district in Eastern Kenya were analysed by gas chromatography-mass spectrometry (GC-MS) and also evaluated for antimicrobial activity. The oil was dominated by monoterpens which accounted for 92.48%. This monoterpene fraction was characterized by a high percentage of eugenol (68.8%). The other major monoterpenes were methyl eugenol (13.21%), cis-ocimene (7.47%), trans-ocimene (0.94%),
-pinene (1.10%) and camphor (0.95%). The sesquiterpenes present in fairly good amounts were germacrene D (4.25%) and trans-caryophyllene (1.69%). The minor sesquiterpenes were -farnesene (0.85%) and
- bisabolene (0.74%). The antimicrobial activities of the essential oils were evaluated against both Gram positive (Staphylococcus aureus, Bacillus spp.) and Gram negative (Escherichia coli, Pseudomonas aeruginosae, Salmonella typhi, Klebisiella pneumoniae, Proteus mirabilis) bacteria and a pathogenic fungus Candida albicans. The oil had pronounced antibacterial and antifungal activities on all the microbes.

Oral hygiene practices and risk of oral leukoplakia

To determine the influence of oral hygiene habits and practices on the risk of developing oral leukoplakia. Case control study. Githongo sublocation in Meru District. Eighty five cases and 141 controls identified in a house-to-house screening. The relative risk (RR) of oral leukoplakia increased gradually across the various brushing frequencies from the reference RR of 1.0 in those who brushed three times a day, to 7.6 in the "don't brush" group. The trend of increase was statistically significant (X2 for Trend : p = 0.001). The use of chewing stick as compared to conventional tooth brush had no significant influence on RR of oral leukoplakia. Non-users of toothpastes had a significantly higher risk of oral leukoplakia than users (RR = 1.8; 95% confidence levels (CI) = 1.4-2.5). Among tobacco smokers, the RR increased from 4.6 in those who brushed to 7.3 in those who did not brush. Among non-smokers, the RR of oral leukoplakia in those who did not brush (1.8) compared to those who brushed was also statistically significant (95% CL = 1.6-3.8). Failure to brush teeth and none use of toothpastes are significantly associated with the development of oral leukoplakia, while the choice of brushing tools between conventional toothbrush and chewing stick is not. In addition, failure to brush teeth appeared to potentiate the effect of smoking tobacco in the development of oral leukoplakia. Oral health education, instruction and motivation for the improvement of oral hygiene habits and practices; and therefore oral hygiene status, should be among the strategies used in oral leukoplakia preventive and control programmes.

Bioactive Extracts from Senecio &lt;i&gt;lyratus&lt;/i&gt;

Dichloromethane, methanol and aqueous fractions from dry methanol extracts of Senecio lyratus showed activity when assayed on brine shrimp (Artemia salina). Except the methanol extract, the other two also showed activity when tested on Escherichia coli (Gram- negative bacteria) and Staphyllococcus aureus (Gram-positive bacteria). Gravity column chromatography of the aqueous fraction led to the isolation of a pure yellowish amorphous compound, Rf 0.62 (uncharacterized) when developed with n-hexane, ethyl acetate (40:60). The compound exhibited acute lethal effects on Aspergillus niger, Bacillus subtilis, Micrococcus luteus, S. aureus and E. coli . Senecio lyratus belongs to the family Compositae (Agnew and Shirley, 1994) and is an ethnomedically important plant. It is distributed in altitudes between 1500m and 2760m above sea level and in Meru district, Kenya it is used for treatment of wounds and as an emetic (Kokwaro, 1976). The chief chemical components of the genus are pyrrolizidine alkaloids (Robins and Fortschr, 1982). Journal of Agriculture, Science and Technology Vol. 2 (1) 1999: 77-80

Major and minor surgery output at district level in Kenya: review and issues in need of further research

Major and minor surgery is a service of great importance both for the people in need and for health workers and managers trying to develop a comprehensive primary health care service. While in highly industrialized countries some 5000-9000 major operations are performed per 100,000 people per year, the rates in East Africa in the early 1990s were in the range of 70-500. In our study all surgical operations performed at hospitals and clinics in Meru district during 12 months in 1990-1991 were listed on record forms including age, sex and home address of patients, and type of operation. Totally 3,415 major operations were recorded, corresponding to 263/100,000 people (88 for males and 434 for females), and the most common major operations were caesarean section, tubal ligation, explorative laparotomy, eye/lens removal and hernia repair. Assuming that the basic need in eastern Africa is about 1,000 major operations/100,000/year, it appears that only 7-50% of this basic need was available in this rural area. The epidemiological basis for such estimates is however rather weak and the information systems are unsatisfactory. More accurate data are required both on descriptive epidemiology and on surgical service output as a basis for planning. Comparisons are difficult due to poorly standardized epidemiology and output indicators. We examine, from a health planning perspective, four possible methods of quantifying the major surgery output: (a) the annual number of major operations per 100 hospitals beds; (b) the number per 1000 inpatient admissions; (c) the number per 10,000 new out-patient consultations, and (d) the annual number per 100,000 catchment area population. The mean number per 100 beds was 310 with a range from 452 to 140; the mean number per 1000 admissions was 74 ranging from 88 to 31, the number per 10,000 new outpatient visits was 96 ranging from 188 to 55, and the mean number per 100,000 catchment area population was 263 for the entire district with a range from 383 to 119 among the five hospitals. We conclude that options (1) and (2) are useful and implementable, (3) is less useful but implementable, and option (4) is potentially very useful but not easily implementable until a catchment area population definition is agreed. Minor surgery is even less well investigated, and there are hardly any studies at all from low-income countries. Our data from Meru demonstrate that the one-year output in a population of 1.3 million people was 26,858 (2,066/100,000 people/year) of which about 82% were done at the hospitals in the area. The smaller clinics did on average only 1.8-6.4 minor operations per month. The basic need for minor surgery in these areas has not been estimated, so the unmet need must be considered unknown. Further research is recommended in the following areas: epidemiological estimates of surgical service need in eastern Africa, critical review of the health information systems with regard to surgery, quality of major and minor surgery services especially in rural areas, and reasons for low surgical output at small clinics; possible remedies.

Palliative Care in Kenya

In August and September 2001, Dr. David Allbrook from Perth, Western Australia, traveled to Maua Methodist Hospital, North Meru District, Kenya, on an International Association for Hospice and Palliative Care Traveling Fellowship. The visit of Professor Allbrook provided a valuable opportunity that enabled Dr. Dietmar Ziegler, and the staff at Maua Methodist Hospital to put together a workable proposal for a sustainable community-based palliative care program.

THE STATUS OF POTATO LEAFROLL VIRUS IN KENYA

SUMMARY A survey of potato leaf roll disease conducted in major potato growing regions of Kenya (Meru, Kiambu, Nyamira and Kisii districts) revealed the highest incidence in Kisima location, Timau division of Meru district and an absence of PLRV in leaf-rolled samples from Githongo location of the same district. The lowest incidence was recorded in Kisii district. The virus was detected in the phloem tissues of potato sprouts and leaves by tissue blot immunoassay (TBIA). The method was found to be simple, rapid and sensitive in detecting PLRV in infected potato plants. In Myzus persicae Sulz., the Acquisition Access Period (AAP), Inoculation Access Period (IAP) and the Latent Period of PLRV, isolated from potato variety ‘Pimpernel’ collected from Tigoni location, Kiambu district, were typical of PLRV. It is suggested that virus control in potato in Kenya can be made more effective by planting virus-free seed-tubers and by early treatment with insecticides. Additionally, volunteer plants and alternative hosts should be rogued and destroyed because they serve as sources of virus for subsequent infections.